EP2783747B1 - Method and device for the contactless mixing of liquids - Google Patents

Description

The invention generally relates to a method and a device for non-contact mixing of liquids or for mixing particles in a liquid and in particular for mixing aqueous solutions. In accordance with the invention, directed liquid radiation is generated by targeted irradiation of electromagnetic radiation into the liquid in order, for example, to transport particles, preferably particles dissolved in the liquid, to a surface or boundary surface of a sample chamber or a surface of a liquid volume in order to mix the particles the liquid, in particular at the surface / interface to provide. The invention is advantageous in that a "depletion layer" or an "enhancement layer" with a reduced or increased particle concentration at the surface / interface is avoided, so that surface-based measurement methods can be improved.

The invention is also advantageous in that it allows small volumes (micro-volumes), which are difficult to mix, for example, due to mechanical effects such as shaking or shaking, to be mixed.

In particular, the invention also relates to a method and a device for investigating specific and nonspecific interactions or interactions of particles, which are preferably dissolved in a liquid, with surfaces or interfaces.

BACKGROUND OF THE INVENTION

The measurement of physical, chemical, biochemical and / or biological processes, such as reactions, binding and attachment processes and other interactions of particles with surfaces are of great interest in the fields of quality control, drug discovery, medicine, basic research and molecular diagnostics. To investigate these processes, methods such as Reflectometric Interference Spectroscopy (RlfS), Bio-Layer Interferometry (BLI), Surface Plasmon Resonance (SPR), Quartz Crystal Microbalances (QCM), Surface Acoustic Wave, Short AOW (SAW for surface acoustic wave), Enzyme Linked Immunosorbent Assay (ELISA), or nanopores or transistors (Next Generation Sequencing).

Further exemplary methods are fluorescence measurements, fluorescence anisotropy measurements, Förster resonance energy transfer measurements (FRET), total internal reflection fluorescence microscopy (TIRFM), backscattering interferometry measurements (BSI), absorption measurements, spectroscopic measurements, AlphaScreen® assays , MicroScale Thermophoresis Measurements (MST), Patch Clamp Measurements.

1. a) Bindung (Messung der Bindungsrate/Bindungskinetik), Verarmungsschicht stört. Hier gibt man eine Lösung in die Probenkammer bestehend aus Puffer und gelösten zu untersuchenden Partikeln A der Konzentration [A]. Die Bindungskinetik wird beschrieben durch die Rate gamma: γ=k_on * [A] + k_off d.h. die Bindungsrate (Assoziationsrate) k_on kann bei Zugabe des Puffers mit Partikel A nicht unabhängig von der Dissoziationsrate k_off gemessen werden. Man kann nur eine apparente Rate gamma messen die aber von der Konzentration [A] abhängt. Man will aber oft die Konzentrationsunabhängigen Raten k_on und k_off bestimmen. Deshalb ist auch b) nötig.
   Bei a) stört die Verarmungsschicht (Anbindung, Assoziation) bei b) stört die Anreicherungsschicht (Dissoziation).
2. b) Messung der Dissoziation/Dissoziationsrate k_off, Anreicherungsschicht stört (siehe bsp. auch " Blocking rebinding with soluble receptor" in J. Mol. Recognit. 1999;12:293-299 ).

Preferably, the particles to be examined are provided in a liquid, preferably an aqueous solution. Surface-based methods generally rely on the particles to be tested to reach the surface of the liquid or the surface of a sample chamber for a longer period of time, the measuring time or incubation or processing time. Due to the finite concentration of the particles in the liquid as well as due to the limited diffusion constant (rate of diffusion) of the particles, often forms a so-called "depletion layer" (English "Depletionlayer", see for example J. Mol. Recognit. 1999; 12: 293-299 ) at the surface or interface. This depletion layer can lead to a falsification of the measurement results or to a slowing down of the reaction or investigation on the surface. Correspondingly, in certain applications, for example when measuring the k _off rate (dissociation rate), in which it is measured how and how quickly particles (eg antibodies) previously bound to the surface detach themselves from it, an "enrichment layer" can be formed form releasing particles. This enrichment layer can lead to an undesired so-called "re-binding" / re-binding / re-binding of the dissolving particles. Both the depletion layer and the enhancement layer can lead to a falsification of the measurement results for the following reasons:

1. a) Binding (measurement of binding rate / binding kinetics), depletion layer disturbs. Here, a solution is introduced into the sample chamber consisting of buffer and dissolved particles A of the concentration [A] to be examined. The binding kinetics is described by the rate gamma: γ = k _on * [ A ] + k _off ie the binding rate (association rate) k _on can not be measured independently of the dissociation rate k _off when adding the buffer with particle A. One can only measure an apparent rate of gamma, which depends on the concentration [A]. But you often want that Determine concentration-independent rates k _on and k _off . Therefore b) is necessary.
   In a) the depletion layer (binding, association) at b) disturbs the enrichment layer (dissociation).
2. b) Measurement of dissociation / dissociation rate k _off , enrichment layer interferes (see also " Blocking rebinding with soluble receptor "in J. Mol. Recognit. 1999; 12: 293-299 ).

Since, as described in a), the k _on and k _off can not be measured independently, a second experiment is necessary to determine k _off alone and then together with a) or a repeated measurement of a) at different concentrations [A ], can determine the k _on:
Here, only the buffer, without Particle A, is added to the sample chamber in which the binding of A was previously measured. In the sample chamber A is bound to the surface, you try it with the buffer "wegzuspülen" or replace, in order to measure the pure k _off of A. Thus, if pure buffer is bound to a sample chamber in which A is bound to the surface (or bound to the molecules B immobilized there), then a new chemical equilibrium must be established (the previously set chemical equilibrium has become for a buffer of A contains set), which causes the molecules A to dissolve. If you move the dissolving molecule A away fast enough, it will not be able to re-bind to the surface (which would cause you to measure gamma again, so k _on and k _off at the same time) and you can measure the pure k _off rate. If A is not transported away fast enough, the enrichment layer forms. The k _on and k _off are usually given in the units: k _on : 1 / ([s] * [M]) or k _off : 1 / [s].

In known methods, it is attempted to reduce this depletion layer or enrichment layer by a constant liquid flow, which is generated, for example, by external pumps. This approach has the great disadvantage that a large dead volume is created by the outer pumps, valves and / or hoses and the whole system is very error prone. In addition, leaks, contamination of hoses and valves, cross-contamination from old samples that could not be completely removed, cause further measurement errors. Because with the users often very little or very expensive sample material is present, the dead volumes discussed above are a major economic disadvantage. In addition, usually very large / voluminous, difficult to transport equipment for controlling and regulating the pumps and valves and thus the liquid flow are advantageous. Among other things, this can prevent their use in "point of care" / "point-of-need" diagnostics.

Another method of avoiding the depletion layer moves or "shakes" the sample chamber macroscopically with respect to a surface sensor. A problem with this method, however, is that the sample chamber must be open to the outside and so can evaporate the aqueous solution and / or can be contaminated by external influences. The mechanical "shaking" of the open sample chamber is also problematic, since the shaking overflow liquids / "spill" and so can penetrate into adjacent open sample chambers.

Next to the patent DE 103 25 307 B3 which describes a method of mixing liquids in a microcavity utilizing sound-induced flows. Documents U.S. Patent 5,823,676 . EMIR VELA ET AL: "Non-contact mesoscale manipulation using laser-induced convection flows", INTELLIGENT ROBOTS AND SYSTEMS, 2008. IROS 2008. IEEE / RSJ INTERNATIONAL CONFERENCE ON, IEEE, PISCATAWAY, NJ, USA, September 22, 2008 (2008- 09-22), pages 913-918 , and DUHR S ET AL: "Thermophoresis of DNA determined by microfluidic fluorescence", EUROPEAN PHYSICAL JOURNAL E. SOFT MATTER, EDP SCIENCES, IT, Vol. 15, No. 3, November 1, 2004 (2004-11-01), pages 277 -286 disclose the mixing of liquids by the generation of a thermal convection flow.

It is an object of the present invention, in particular, to reduce or overcome the above-mentioned disadvantages of the prior art and to provide a new, preferably more advantageous method and a corresponding device and system.

SUMMARY OF THE INVENTION

The object is solved by the features of the independent claims. Further preferred embodiments will become apparent from the subclaims and the following aspects or exemplary embodiments.

The invention generally relates to a method for mixing fluids, preferably liquids or for mixing particles in a fluid or a liquid. Preferably, the invention relates to a method for mixing of dissolved and / or undissolved particles in the liquid. In general, the present invention relates to the mixing of any kind of particles or particles such as (bio) molecules, (nano) particles, (micro) beads, (bio) polymers, paints, emulsifiers, cells (biological cells), viruses, bacteria, Lipids, vesicles, liposomes, nanodiscs, pigments, dispersing additives, pastes.

Preferably, the liquid is provided as a liquid volume in at least one sample chamber, wherein the sample chamber may be open or closed. As an alternative to a sample chamber, the liquid can also be provided in the form of a drop, wherein according to the invention a thermal convection flow is generated within the droplet. For example, the liquid drop may be provided on a suitable slide (see discussion below) and, for example, surrounded by an oil layer to prevent evaporation. According to a preferred embodiment, the provision of very small volumes of liquid in glass capillaries already suffices.

Regardless of whether the liquid is provided with therein (dissolved or undissolved) particles within a sample chamber or within a drop for a measurement, a convection flow is achieved in the liquid volume by irradiation of electromagnetic radiation in the liquid volume and in particular a mixing of Liquid with the particles present therein at a surface of the liquid volume or at an interface or boundary layer between the liquid volume and a material layer of the sample chamber achieved. The inventive method and the associated apparatus is thus applicable to measuring methods in which preferably measured at the surface or interface of a liquid, since according to the invention a depletion zone, depletion layer, enrichment zone, enrichment layer or a concentration shift at the surface or interface is avoided.

According to the invention, in particular a good mixing in contact surfaces between solids (for example inner surface of a sample chamber or of glass capillaries) and the liquid is to be achieved. However, a surface or contact surface according to the invention is not limited to a flat surface, but may also be three-dimensional or fractal, e.g. when dextran or dendrimer coated glass substrates are used and the interaction between e.g. Antibody and antigen takes place on / in the dextran layer.

Preferably, the thermal convection flow is generated by means of at least one electromagnetic radiation source, preferably a light source. According to the invention, the thermal convection flow is generated by means of an infrared (IR) radiation source. For example, IR radiation can be generated with known IR radiation sources and preferably positioned locally by an optical means (eg, lens and / or mirror / reflector) in the liquid also be focused. Depending on the experimental setup according to the invention or the application, it may also be advantageous if the IR beam is parallelized or even defocused (divergent). According to the invention, IR LEDs are used as the radiation source.

In particular, the liquid is preferably heated locally at the location of the radiated beam and thus generates the thermal convection flow. In other words, the present invention preferably produces liquid streams directly, and preferably purely optically and in particular completely contactless, directly in the liquid / solution with the particles. Since liquids to be examined are often aqueous solutions, it is particularly advantageous in these cases to select the electromagnetic radiation in the infrared wavelength range, due to the advantageous absorption behavior.

The inventors of the present invention have also recognized that an aqueous solution not only absorbs the energy of the IR laser radiation, but also the pulse of the photons of the IR laser radiation (light pressure) has an influence on the convection behavior (see FIGS. 2A, 2B ). The energy absorption heats the aqueous solution locally at the location where the IR laser radiation is radiated into the aqueous solution, which leads to thermal convection. In addition, during absorption, the momentum of the photons of the IR laser radiation is transferred to the aqueous solution. As a result of this light pressure (or jet pressure), the flow velocity of the thermal convection, depending on the orientation of the IR laser radiation relative to the vector of gravitation, can be amplified (antiparallel to gravitation) or attenuated (parallel to gravitation). The laser radiation can also be aligned vertically or obliquely to the gravitation.

The wavelength of the preferred IR radiation is preferably in the range 1200 nm to 2000 nm. More preferred are the specific IR laser wavelengths: 980 nm (+/- 10 nm); 1450 nm (+/- 20 nm); 1480 nm (+/- 20 nm); 1550 nm (+/- 20 nm) and 1920 nm (+/- 20 nm).

The invention also relates to a device for carrying out the method according to the invention. In particular, the method according to the invention is preferably used in combination with surface / interface-based measuring methods / measuring devices. This allows, for example, specific chemical, biochemical Interactions at interfaces are safely and reliably investigated, preferably in extremely small volumes. In addition to specific interactions of particles with interfaces, non-specific effects such as "sticking", physisorption, chemisorption, sorption, adsorption, absorption, electrochemical processes, catalytic processes, etc. can also be investigated

Thus, the mixing method according to the invention can be used, for example, in combination with measuring device for determining optical properties on a thin layer, whereby, for example, chemical, biochemical, medical and / or physical reactions, binding and / or addition processes as well as other interactions on the thin layer are detected can. In known measuring methods, for example, light, preferably light of a specific wavelength, is irradiated onto a sample to be examined, the sample being bound to a thin layer. Changes in the optical layer thickness are detected or measured, for example, by means of interference phenomena, which results in conclusions on reactions of the examined sample with a suitably pretreated thin layer.

Another advantage of the method according to the invention, for example, is that there is no dead volume. According to the invention, the volume consumption can be reduced from a few 100 microliters to a few milliliters to a few nanoliters to a few microliters. Volumes of from 1 microliter to 10 microliters are preferably used as the volume according to the invention. Elaborate flow cells, microfluidics, pumps, valves and hoses are preferably eliminated, whereby a device according to the invention is very robust and preferably can not be contaminated by any residues in hoses and / or valves and it also prevents loss of sample / particles in the sample Adherence (adsorption / chemsorption / physorption) of the particles to the surfaces of the hoses and valves (more generally: to the surfaces of the dead volumes).

Since the liquid streams are preferably generated completely contactless, purely optically, cross-contamination and / or contamination of the samples can be reduced and preferably even excluded. According to the invention, both open and closed sample chambers can be used, whereby vaporization / evaporation of the (aqueous) solution can also be avoided by closed sample chambers. This is advantageous, for example, in that significantly longer measurement times are possible.

Generally, convection is caused by a flow that can carry particles. Cause of the transporting flow can basically be different forces, such. As weight or forces resulting from pressure, density, temperature or concentration differences. A distinction is made here between forced convection, in which the particle transport is caused by external action, for example a blower or a pump, and free or natural convection, in which the particle transport is preferably caused exclusively by effects of the temperature gradient. The method of the invention preferably produces a free or natural convention, i.e., convection caused by a temperature gradient. The temperature increase is preferably so low that the particles or the sample are not damaged and / or negatively affected.

For example, free convection due to thermal density differences may be described as follows: When heated, fabrics tend to expand (except, for example, the density anomaly of the water). Under the influence of the gravitational force, areas of lower density rise within the fluid against the gravitational field (buoyancy), while areas of higher density sink therein. For example, if heat is applied to the bottom of a sample chamber and the top of the sample is allowed to cool, a continuous flow is created: the liquid heats up, expands, and rises. Once there, the liquid cools down, contracts again and sinks to be heated again below.

The velocity of the liquid streams of the thermal convection according to the invention can preferably be determined by varying the optical energy or power, the focusing or defocusing, the intensity, the direction, the parallelism (or also the convergence and divergence) and / or the position of the focus relative to surface / thin film, the number of beams (laser beam can be split to heat several places at the same time), the duration of irradiation, pulse width modulation (pulse height, pulse duration, repetition rate), wavelength, moving beam velocity, irradiated radiation and / or be changed or controlled relative to the direction of gravity relative to gravity. The position of the irradiated radiation (eg position of the focus of the irradiated radiation) can vary, for example the focus can be positioned in all three spatial directions by means of mirror systems (see laser scanner) and be moved at different speeds. Since the present invention can also generate liquid streams perpendicular to the surfaces of sample chambers by means of optically generated thermal convection (as opposed to liquid streams generated by external pumps), mixing the liquid and reducing a depletion layer is very efficient.

The rate of thermal convection depends, among other things, on the chamber thickness (height in the direction of gravity) of the sample chamber and, in particular, on the chamber geometry. In particular, edge surfaces of a sample chamber can significantly influence the speed of thermal convection. Preference is given to sample chambers that are thick enough (for example> 0.05 mm) to achieve a desired rapid flow velocity of the thermal convection in order to avoid the " depletion layer" or an enrichment layer.

In particular, it is preferred according to the invention to achieve a thermal convection such that preferably a laminar flow is generated, preferably at low Reynolds numbers (Reynolds number Re <1000). It is preferable to use sample chambers (also liquid drops or water drops) with a volume of <= 200 μl (microcavity). In addition, a layer thickness of at least 0.05 mm is preferred because at lower layer thicknesses or smaller thicknesses of the sample chamber, the convection effect is too weak to achieve a desired mixing. It is also preferable to use layer thicknesses of the liquid or thicknesses of the sample chamber not greater than 11.5 mm (well depth in the case of multiwell plates).

An exemplary convection velocity for a sample chamber that is 1 mm in height and 5 mm in diameter, 20 μl in volume, 52 ° C chamber temperature, 1480 nm IR laser with 75 mW light output is at medium speed of about 0.4 mm / s. A typical or average extent of the convection flow lines in this example is about 2 mm in diameter.

For the following sample chamber geometry: disc with 0.05 mm height and 5 mm diameter; Chamber temperature: 20 ° C; IR laser: 1480 nm; Temperature increase by IR laser radiation: 1.25 K; is the typical / average velocity of convection at about 0.0005 mm / s when the IR laser radiation is aligned antiparallel to gravity, so the thermal convection supported.

In the following, a comparison of the convection rate with the diffusion speed of the particles is discussed. This comparison shows, for example, that the finite, and therefore too slow, diffusion can lead to the problem of the depletion layer. Exemplary diffusion constants D of biomolecules are between 1 μm ² / s and 400 μm ² / s.

Preferably, the movement / displacement / mixing of the particles due to the convection flow is adapted to the movement of the particles (Brownian motion) due to their diffusion (diffusion constant D). Depending on the diffusion constant of the particles to be examined, there is a preferred average flow velocity of the thermal convection to be used, and thus, for example, preferably also radiation intensities or configurations for the irradiation of the radiation to be used. Due to the very flexible and easily variable and preferably purely optical construction according to the invention, the convection flow and thus the mixing can preferably be adjusted to the particles to be examined, without a new structure having to be built specifically for each particle.

The method according to the invention for the mixing of liquids can be used particularly advantageously in analytics, in particular in analytical methods in which the binding kinetics of biomolecules (for example association and dissociation rate constants; k _on , k _off , also rates for the Hin (k _on ) and back reaction (k _off )) and the binding affinity, described for example by the dissociation constant K _d = k _off / k _on , may be of importance. These rate constants can be exemplified as follows. Assume a chemical reaction of molecule A of concentration [A] with molecule B of concentration / surface density [B] to complex D of concentration [D]. The kinetics of this reaction, ie the kinetics of complex formation, can be described by the following equation, which thus also shows the meaning of the rate constants: $$\frac{d}{\mathit{dt}}\left[D\left(t\right)\right]=k_{\mathit{on}}*\left[A\left(t\right)\right]*\left[B\left(t\right)\right]-k_{\mathit{off}}*\left[D\left(t\right)\right]$$

Further examples for the application of the mixing according to the invention are "diagnostics" (mixing also important in ELISA), the field of electrochemistry, the range of catalysts, or the area of quality control ("sticking" to surfaces to avoid it). In addition, rates of "sticking" of particles or measuring the strength of "sticking"("sticking", physorption, chemsorption, adsorption, absorption) can be measured.

Even with multiwell plates (place of use: ELISA) mixing by optically generated thermal convection is advantageous. For 384 well plates and / or 1536 well plates, the adhesion of the fluid to the surfaces of the wells (microcavities) is so great that the fluid in the wells on a shaker / vibrator is no longer properly mixed. Mixing by means of optically generated thermal convection can also be advantageous in the case of 96-well plates or other reaction vessels, for example if mechanical shakers or other mixing devices, such as e.g. magnetic stirring fish for reasons such as e.g. avoid contamination can not be used. By means of an IR laser for e.g. Even if only every few seconds in each well is used, a better mixing in the well (volume <200 ul) can be achieved. Also according to the invention, especially in this application, thermal convection is to be generated for mixing by means of IR LEDs. IR LEDs are cheap; one can e.g. Insert 384 LEDs or 96, or 24 or 16 to mix many wells simultaneously. IR LEDs typically have less light output than IR lasers, but since the layer thickness of the aqueous solution in the wells is very large (typically> 1 mm), the IR radiation is very well absorbed (Beer-Lambert's Law) and so are IR LEDs powerful enough.

In general, the method according to the invention is advantageous for reaction kinetics measurements or biomolecule analysis. In particular, the method can be used with NanoTemper® capillaries (for example, glass capillaries with inner diameter of 0.05 mm to 0.8 mm), preferably with inner diameters of 0.2 mm, 0.35 mm, 0.5 mm and 0.8 mm and outer diameters less than or equal to 1.0 mm. Preferably, no flow cells are necessary and filling of the capillaries can be carried out purely passively by capillary forces. The inner surface of the glass capillary may be untreated or at least partially specifically coated / modified (e.g., with antibody, antigen, DNA, RNA, PNA, TNA, proteins, peptides, cells, polymers, etc.) or not.

The disclosed method can generally be carried out with sample compartments having at least one region which is transparent. Transparency in physics is the ability of matter to transmit electromagnetic waves (transmission). In everyday life, the term is usually related to light, that is, to the spectral range of electromagnetic radiation visible to humans. According to the invention, the transparent material is preferably in a wavelength range between 200 nm to 2000 nm permeable, ie preferably also for infrared light and / or UV light. Preferably, the transparent material is transparent to light in the range of 200 nm to 900 nm, preferably 250 nm to 900 nm, preferably 275 nm to 850 nm. Preferably, the transparent material is also transparent to light of the following wavelength: 940 nm to 1040 nm (preferably 980 nm +/- 10 nm), 1150 nm to 1210 nm, 1380 nm to 1600 nm (preferably 1450 nm +/- 10 nm and / or 1480 nm +/- 10 nm and / or 1550 nm +/- 10 nm), 1900 nm to 2000 nm (preferably 1930 nm +/- 10 nm). In addition, it may already be sufficient if only 10% of the incident light is transmitted through the transparent material, preferably at least 20%, 30%, 40%, 50%, 60%, 70%, 80% or at least 90% or more.

The transparent material may comprise, for example, glass and / or a polymer. Possible materials are borosilicate or borosilicate glass such as Brosilikatglas 3.3 (for example DURAN glass), quartz glass, such as Suprasil, Infrasil, Synthetic quartz glass or silica glass, soda lime glass, Bk-7, ASTM Type 1 Class A glass, ASTM type 1 Class B glass. The polymer may be PTFE, PMMA, Zeonor ™, Zeonex ™, Teflon AF, PC, PE, PET, PP (polypropylene), PPS, PVDF, PFA, FEP, and / or acrylic glass].

The disclosed method can also be used with pipette tips, in particular with at least partially transparent pipette tips, for example made of polypropylene. The process according to the invention can also be used with reaction vessels, for example reaction vessels made of glass or plastic ("Eppis"), preferably transparent glass and plastic. For example, with reaction vessels for the "Realtime PCR (Polymerase Chain Reaction)". The method according to the invention can also be used with chambers / capillaries for electrophoresis, preferably capillary electrophoresis. The method according to the invention can also be used in the detection range of HPLC / UHPLC (High Performance Liquid Chromatography (HPLC).) The disclosed method can also be used with microfluidic chambers / microfluidic chips The method according to the invention can be used with sealed / sealed multititre plates (multiwell plates). The disclosed method can be used in sealed / sealed ampoules, for example glass ampoules or plastic ampoules, preferably transparent ampoules, for example substances in the ampoules for forensic or diagnostic tests be enclosed, which must not be contaminated and therefore preferably should not be opened.

The inventive method can also be done with multi-well plates (multiwell plates) which have a non-transparent bottom. Preferably, however, multititer plates (multiwell plates) for filling with pipettes or pipetting robots are open, preferably open at the top.

The process according to the invention can also be used everywhere, for example, where mixing / flow generation by means of external flow (pumping) and / or mechanical shaking is not possible (for example all closed reaction vessels / microcavities) or useful, but the aqueous solution is optically accessible.

The method according to the invention can be used in diagnostics, also for mixing in ELISA plates. Another exemplary application is quality control.

The mixing method according to the invention can be combined with a multiplicity of different known measuring and reading techniques, in particular for measuring specific and unspecific interactions of particles at surfaces / interfaces. The following typical surface techniques are mentioned by way of example: For measurement, methods such as reflectometric interference spectroscopy (RlfS), Bio-Layer Interferometry (BLI), the surface plasmon resonance (English Surface Plasmon Resonance, SPR), the quartz crystal microbalances (English Quartz Crystal Microbalance, QCM), surface acoustic wave (SAW), enzyme-linked immunosorbent assay (ELISA) or nanopores or transistors (Next Generation Sequencing). For example, these measuring methods may be performed by a combination of e.g. Glass capillaries of certain diameter as a sample chamber of the aqueous solution with the particles, IR laser / LED for generating a thermal convection in the aqueous solution in the glass capillaries and a corresponding measurement or experimental arrangement can be improved.

In general, the disclosed method for mixing liquids or particles with a liquid relates to the steps of providing a volume of liquid and generating a thermal convection flow on at least one surface / interface of the liquid volume by irradiating electromagnetic radiation into the liquid volume.

The liquid volume may be provided, for example, in a sample chamber that is open or closed. Preferably, a microcavity may serve as the sample chamber, more preferably a capillary or a pipette tip. Preferably, a sample chamber should have at least one region that is at least partially transparent. Preferably, the sample chamber has a thickness of 0.01 mm to 25 mm, preferably 0.05 mm to 12 mm, preferably 0.05 mm to 1 mm. According to a preferred embodiment, capillaries have an inner diameter of 0.01 mm to 3 mm, preferably 0.05 mm to 0.8 mm, wherein the capillaries are preferably at least partially made of glass or other at least partially transparent materials. The volume of liquid may also be provided as drops on a slide.

Preferably, the sample chamber has a volume of 0.001 μl to 1000 μl, preferably from 0.1 μl to 200 μl, preferably from 1 μl to 10 μl, preferably from 1 μl to 6 μl.

The surface of the liquid volume is preferably formed by the interface between liquid volume and a surface of the sample chamber or, for example, by the interface between liquid volume and a surface of the slide.

The liquid used is preferably an aqueous solution, but is not limited thereto.

The electromagnetic radiation preferably has IR radiation or only wavelengths in the IR range and is preferably generated by a laser and / or an LED.

The incident radiation may be parallel and / or anti-parallel to gravity and / or may include a component oriented perpendicular to gravity.

The irradiated radiation preferably generates a temperature gradient of 0.001 K / μm (= 1 K / mm) to 5 K / μm (= 5000 K / mm), preferably from 0.001 K / μm (= 1 K / mm) to 2 K / μm (= 2000 K / mm).

More preferably, the temperature gradient is generated in a small range, preferably in a range of 0.00001 mm ² to 1 cm ² , preferably generated in a range of 0.0001 mm ² to 12 mm ² .

A detection area for measuring properties of the liquid or particles in the liquid may be spaced from the area in which the radiation is irradiated. For example, the detection area may be spaced at least 0.01 mm from the incident beam, the distance preferably being measured perpendicular to the direction of irradiation.

According to a further embodiment, the detection area and the irradiation area may also overlap. Thus, the detection surface is often larger than a well-focused laser beam (for example, 2μm diameter can be achieved with IR). Therefore, in this embodiment, preferably the entire detection surface is swept by the convection flow. The overlap of the detection area and the irradiation area is, for example, in the structures Fig. 5 or Fig. 6 applicable. Since everything is focused by the same optics, the heating focus of the IR radiation is preferably within the detection range

Preferred flow velocities of the convection flow are in the range of 0.0001 mm / s to 10 mm / s, preferably 0.0005 mm / s to 2 mm / s.

The mixing method according to the invention is particularly advantageous when it is combined with additional measuring methods. In particular, the present invention also relates to a method for investigating molecular interactions on and / or in a thin layer in a liquid volume according to claim 7. Preferably, a sample chamber is provided for carrying out such a measurement in the form of a capillary, pipette tip, multiwell plate or a microfluidic chip.

The interaction is preferably measured by means of reflectometric interference spectroscopy (RlfS), surface plasmon resonance (SPR), enzyme-linked immunosorbent assay (ELISA), quartz crystal microbalances (QCM), and / or surface acoustic wave, (surface acoustic wave; SAW). According to further preferred embodiments, the measurement of the interaction may be at least one method from the group: Reflectometric Interference Spectroscopy (RlfS), Bio-Layer Interferometry (BLI), Surface Plasmon Resonance (SPR), Quartz Crystal Microbalance (QCM), Surface Acoustic Wave, SAW, Enzyme linked immunosorbent assay (ELISA), nanopores or transistors (Next Generation Sequencing).

The present invention also relates to a device for mixing liquids or particles with a liquid, in particular for carrying out a method described above, according to claim 9. Finally, a system with a device for mixing and a device for measuring is disclosed, wherein the Measuring device preferably for measuring a specific or nonspecific interaction of the particles with a surface / interface of a sample chamber or a slide is used.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

ein beispielhaftes IR-Absorptionsspektrum von Wasser bzw. einer wässrigen Lösung mit eingezeichneten Absorptionsmaxima;

Fig. 2A & 2B

schematisch den Einfluss der Orientierung eines eingestrahlten IR-Laserstrahls relativ zur Gravitation auf die erzeugten thermischen Konvektionen;

Fig. 3

eine schematische Darstellung des bevorzugten Detektionsbereichs zur Messungen der spezifischen und unspezifischen Wechselwirkung von Partikeln innerhalb einer Probenkammer;

Fig. 4

eine weitere Ausführungsform einer Anordnung für das offenbarte Verfahren bei der insbesondere der Strahlenverlauf beteiligter Lichtstrahlen schematisch eingezeichnet ist;

Fig. 5

eine schematische Darstellung einer Versuchsanordnung zur Messung von spezifischen bzw. unspezifischen Wechselwirkungen von Partikeln mit einer Oberfläche;

Fig. 6

eine ähnliche schematische Darstellung wie in Fig. 5, jedoch mit einer weiter oben angeordneten Einrichtung zum Einkoppeln eines Laserstrahls zum Erzeugen der Konvektion in der Messzelle;

Fig. 7A & 7B

zeigt schematische Darstellungen des Einstrahlens von IR-Strahlung in Multiwellplatten; and

Fig. 8

zeigt eine schematische Darstellung einer beispielhaften erfindungsgemäßen Versuchsanordnung zur Messung von mehrfarbiger (Multiplexing) Fluoreszenz in einer Multiwellplatte bei der sowohl Fluoreszenzanregung, Fluoreszenzdetektion als auch die Fokussierung der IR-Strahlung durch das gleiche Optische System erfolgt.

Hereinafter, preferred embodiments will be described in detail with reference to the drawings. Show it:

Fig. 1

an exemplary IR absorption spectrum of water or an aqueous solution with absorption maxima shown;

Figs. 2A & 2B

schematically the influence of the orientation of an irradiated IR laser beam relative to gravity on the thermal convections produced;

Fig. 3

a schematic representation of the preferred detection range for measuring the specific and unspecific interaction of particles within a sample chamber;

Fig. 4

a further embodiment of an arrangement for the disclosed method in which in particular the beam path involved light rays is schematically drawn;

Fig. 5

a schematic representation of an experimental arrangement for measuring specific or nonspecific interactions of particles with a surface;

Fig. 6

a similar schematic representation as in Fig. 5 but with an upper arrangement for coupling a laser beam to generate convection in the measuring cell;

Figs. 7A & 7B

shows schematic representations of the irradiation of IR radiation in multiwell plates; and

Fig. 8

shows a schematic representation of an exemplary experimental arrangement according to the invention for the measurement of multicolor (multiplexing) fluorescence in a multiwell plate in which both fluorescence excitation, fluorescence detection and the focusing of the IR radiation by the same optical system.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 3 shows by way of example the detection area 80 for measurements of the specific and unspecific interaction of particles. The sample chamber 45 shown is an example of a capillary.

The detection area 80 is preferably located at the surface / interface of the measurement volume within the capillary 45, i. on the inside of the sample chamber 45. For example, the detection area 80 can be selected around the area of an irradiated IR radiation 30 such that it is smaller, larger or the same size as the area swept by the thermal convection 90.

The detection region 80 may be, for example, a thin layer and contain, for example, antibodies for the specific detection of antigens. In other words, the detection region is located on the surface of the liquid or the surface of the capillary 45. The detection region 80 may, for example, also be composed of several different thin layers, which differ, for example, in their refractive index, polarizability or their fluorescence. The convection is preferably adjusted so that no depletion layer or enrichment layer is formed in the detection area. For example, the thermal convection can be adjusted so that it particles from far outside the Detection area, for example, a few millimeters away, transported into the detection area.

Order can be varied, but it is crucial that there is a certain distance between IR laser focus (determines the "convection rollers") and the place where the interaction is detected on the surface. The distance between them is important as the IR laser produces different thermal convection currents depending on the power and chamber thickness and chamber geometry. You have to set it all up so that you have the right thermal convection currents at the interaction site (to avoid the depletion layer of the molecules).

FIG. 4 shows an exemplary arrangement in which the inventive method is applied. Infrared laser radiation 30 is radiated from below into a sample chamber 45 having a liquid volume, here an aqueous solution with particles 50, and generates a thermal convection 90 in the sample chamber 45. The flow velocities in the liquid are represented by corresponding vectors. In addition, in this example, a symmetrical convection around the irradiated laser beam 30 can be seen. As a detection method for measuring the interaction of the particles 105 dissolved in the liquid with a thin layer (shown hatched) of functionally immobilized molecules / particles 103, the reflectometric interference spectroscopy (RIfS) method is used.

In short, RIfS is a physical method based on the interference of white light on thin layers. This method is used in practice, for example, to investigate molecular interactions. The basic measuring principle corresponds to the Fabry-Perot interferometer. RIfS is mainly used as a detection method in chemo- and biosensors. As sensitive layers mostly non-selective measuring polymers are used, which sort analytes either by their size (so-called molecular sieve effect in microporous polymers) or due to different polarities (eg functionalized polydimethylsiloxanes). In the field of biosensors, for example, polymers such as polyethylene glycols or dextranes are applied to the layer system and immobilized thereon recognition structures for biomolecules. In principle, all substance classes can be used as recognition structures (proteins such as antibodies, DNA / RNA such as aptamers, small organic molecules such as estrone, but also lipids such as phospholipid membranes).

In Fig. 4 In addition, a carrier 46 is shown, which may be part of the sample chamber 45. However, it is also possible that the sample to be examined is provided as a drop or liquid layer on the carrier. The carrier 46 may be made of glass or plastic, for example. On this carrier 46, the thin layer to be examined, comprising a layer 103 of functionally immobilized molecules and another layer 102 of molecules, which is arranged between the layer 103 and the carrier 46, is shown schematically. The layer 102 serves, in particular, for better adhesion of the thin layer on the carrier 46. The layer / layer 102 of molecules (eg PEG or dextran, etc.) which is arranged between the layer 103 and the carrier 46 (illustrated schematically) can be referred to, for example Spacer and / or serve as immobilization aid for the functional molecules of layer 103. The layer 102 also serves in particular for better adhesion of the layer / thin layer 103 on the carrier.

To the functionally immobilized molecules / particles of the layer 103, sample particles 105 can bind. As a result, the thickness of the thin layer increases, the distance of its upper boundary surface 104 to the phase boundary between the thin layer and the support (or the lower boundary surface of the thin layer) is larger. From below irradiated light 31, which is used for the measurement, we now also reflected at the boundary surface 104 after connection of the sample particles 105. The boundary surface 104 is formed opposite to the solution with particles 50, for example, when the particles from the aqueous solution bind to the functionally immobilized molecules in the thin layer 103. The reflected beam 113 at this boundary surface 104 is shown schematically. In addition, the reflected beams 112, 111a, 111b and 110 are also shown, which are reflected at interfaces that lie below the boundary surface 104. Since the incident light has to cover a greater path length up to the boundary surface 104, a shift of the interferogram, which is produced by the superimposition of the reflected electromagnetic radiation 110, 111 a, 111 b, 112 and 113, results. This shift can be measured with time resolution, which allows conclusions about the change in layer thickness and thus the interaction of the dissolved particles 105 with the functionally immobilized particles 103.

For example, the particles 105 in the aqueous solution are biomolecules such as DNA, RNA, proteins, antibodies, antigens, etc. Small molecules, nanoparticles, polymers, peptides, PNA, etc. or even cells, viruses, bacteria, vesicles, Liposomes, microbeads, nanobeads, nanodiscs, etc.

FIG. 5 shows by way of example the application of the method in a concrete experimental arrangement, but without being limited thereto. The reference numeral 1 denotes a light source used for the measurement. For example, the light source 1 may be one or more LEDs, one or more lasers and / or one or more SLEDs (superluminescent LED). The light of the light source 1 serves primarily to irradiate a sample 50 to be examined, preferably to irradiate it vertically. The light emitted by the light source 1 can be changed by means of known optical means, for example by means of a diffuser 4 and / or a lens system (not shown). For example, a diffuser 4 can be used to evenly distribute the light and a lens system can be used to focus the light as desired. Subsequently, in this embodiment, the light passes through a polarizer 5, for example for producing linearly polarized light. In addition, the light can also pass through a filter 14, so that a light beam 31 with defined properties is irradiated onto the sample 50. The filter 14 may, for example, be a wavelength filter, for example a bandpass filter, or a longpass filter or a shortpass filter.

In the illustrated embodiment, the beam splitter 7 is used to divide the light beam into a measuring beam or measuring beam path 9 and a reference beam or reference beam path 11, the measuring beam path being shown at the bottom and the reference beam path 11 pointing to the left to the reference beam. Detector assembly 19 'is shown. The beam splitter 7 preferably has a polarizing property. However, the beam splitter 7 may also be omitted in certain embodiments. Then also eliminates the reference beam path 11, or the whole reference branch of reference beam path 11, reference lens system 17 ', reference detector filter 23' and reference detector 19 '.

In the illustrated embodiment with reference branch, the reference detector array 19 'may be, for example, a photodiode, a photomultiplier (photomultiplier, photomultiplier tube, PMT), a charge coupled device (CCD) camera, a complementary metal (CMOS) CMOS Oxide Semiconductor; complementary metal oxide semiconductor), a diode array, or an avalanche photodiode. The reference branch may have a reference lens system 17 'in front of the reference detector arrangement 19' for imaging / focusing on the reference detector arrangement 19 'and / or a reference detector filter 23', for example a bandpass filter, or a longpass filter or a short-pass filter.

The measuring beam path 9 can, before it hits the sample 50, be changed with additional optical means, which are arranged after the beam splitter 7. Shown is an example of a spot filter 21 and a (first) optical correction element 35, for example, to compensate / correct the phase shift, polarization change and / or optical path change that is possibly generated by the second beam splitter 34 for coupling the infrared laser radiation. In addition, a second optical correction element 36 is shown, which can optionally be extended with a lens or a lens / lens system, for example, the phase shift, polarization change and / or optical path change may be accompanied by the (second) beam splitter 34 for coupling the infrared laser radiation, to compensate / correct. The second optical correction element 36 and / or the optional lens or the optional lens system can also serve to focus the beam paths on the sample 50.

The sample 50 may be deposited on a carrier 46 as a droplet or in a sample chamber 45, as in FIGS FIGS. 2 to 4 shown provided. In particular, a sample chamber may be a capillary, a microcavity, a reaction vessel ("Eppi"), a microfluidic device, or a pipette tip without being limited thereto. The sample 50 to be investigated is preferably a liquid, preferably an aqueous solution, with particles 105 present therein (see US Pat Fig. 4 ), which may be in dissolved or undissolved form.

The support 46 is preferably at least partially transparent, with the illustrated support 46 being a slide glass formed from a glass on which a thin layer 103 is formed. The thin layer 103 to be examined comprises, for example, a layer of functionally immobilized molecules.

The thin layer 103 is influenced by the sample 50 to be examined. For example, interaction of the molecules on the thin layer 103 with the corresponding particles 105 in the sample leads to a layer thickness change (see Fig. 4 ). This change in layer thickness influences the light conducted via the measuring beam path 9 onto the carrier 46 and reflected on the surface of the thin layer, which light is deflected by the beam splitter 7 and imaged on a detector arrangement 19. The measuring branch (to the right of the beam splitter 7) is preferably similar to the detector arrangement 19 or even identical to the reference branch (to the right of the beam splitter 7). In the illustrated embodiment, the detector assembly 19, for example, a Photodiode, a photomultiplier (photomultiplier tube, photomultiplier tube, PMT), a CCD camera (Charge-Coupled Device), a complementary metal oxide semiconductor (CMOS), a diode array or an avalanche Be photodiode. The measuring branch may have a lens system 17 in front of the detector arrangement 19 for imaging / focusing on the detector arrangement 19 and / or a detector filter 23, for example a bandpass filter, or a longpass filter or a shortpass filter.

As already in relation to the FIG. 4 described, the multiple reflection is preferably used at the interfaces of the thin layer for the measurement, wherein the reflected steel with the two detector arrays 19, 19 'are detected. The two detector arrangements 19, 19 'are connected to an evaluation unit which will not be described in detail here.

In order to ensure good mixing in the thin layer 103 and to avoid a depletion layer, according to the invention, light from a laser 32 is irradiated into the sample 50. For irradiation of the laser light is in FIG. 5 the second beam splitter 34 already mentioned above is arranged below the first beam splitter 7. In a further embodiment according to FIG. 6 , in which like reference numerals refer to like components, the second beam splitter 34 is shown above the first beam splitter 7 by way of example. With the aid of the second beam splitter 34, the infrared laser radiation 30, which is emitted by the laser 32 and optionally with an optical means 33, for example lenses, or lens system, for example, collimator for parallelization and / or focusing of the infrared laser radiation is changed, in the measuring beam path 9 coupled. The beam splitter 34 may be similar to the beam splitter 7, be the same, or have other properties. For example, the beam splitter 34 may be a dichroic mirror or a "hot mirror". It is again explicitly emphasized here that the irradiated electromagnetic radiation 31 is used for the measurement, whereas the irradiated electromagnetic radiation 30 serves to generate a convection.

It is also explicitly emphasized here that the experimental arrangement described above is only one of many examples according to the invention and the invention is by no means restricted to a specific arrangement of the optical means described above. In particular, the experimental setup is not limited to the orientation shown. So the light can come from the bottom left or right instead of from above and the corresponding optical Means be moved or rotated accordingly. In addition, the order of the optical means is not limited to the illustrated embodiment and can be changed according to the desired irradiation and measurement characteristics. Instead of the reflection shown, a transmission can also be measured according to the invention. One skilled in the art will readily recognize, however, that the convection generation method of the present invention can be easily implemented even in such a transmission test setup. Also in this context is on the Fig. 6 referenced, the one to Fig. 5 shows very similar experimental arrangement, but irradiates the light of the IR laser at a different location.

FIGS. 2A and 2B show by way of example the influence of the orientation of an irradiated IR laser beam 30 relative to gravity on the thermal convection within a sample chamber 45, in which an aqueous solution 50 with particles dissolved therein (not shown) is located. Also marked are the velocity vectors (arrows) and the flow lines (lines) of the thermal convection 90.

Is the laser radiation as in Fig. 2A aligned antiparallel to gravity, so the beam pressure / light pressure enhances the thermal convection, ie, the flow velocity is higher than when the laser radiation is aligned parallel or perpendicular to gravity.

Is the laser radiation as in Fig. 2B aligned parallel to gravity, so the beam pressure / light pressure attenuates the thermal convection, the flow velocity is lower than when the laser radiation is aligned anti-parallel or perpendicular to gravity.

FIGS. 7A and 7B show by way of example the irradiation of radiation, preferably IR radiation, for example of laser radiation 30 in the filled with an aqueous solution 50 "well" 45 a multiwell plate, such as a 96, 384 or 1536 well multiwell plate. The irradiated IR radiation 30 generates a thermal convection 90 in the irradiated sample chamber "well" 45.

In the Fig. 7A the IR radiation 30 is irradiated through a transparent bottom 47 of a multiwell plate.

In the Fig. 7B the IR radiation 30 is not radiated through the bottom, but directly into the aqueous solution 50 in the sample chamber "Well" 45, here from above. For example, this multiwell plate may have a non-transparent bottom 48, but also, for example, a transparent bottom or even a partially transparent bottom.

FIG. 8 shows by way of example the application of the disclosed method in a concrete experimental arrangement, but without being limited thereto. Again, the same reference numbers should refer to the same or similar parts. The reference numeral 1a denotes a light source used for the measurement. For example, the light source 1a may be one or more LEDs, one or more lasers, and / or one or more SLEDs (Super Luminescent LED). Reference numeral 1b denotes a light source used for the measurement. For example, the light source 1b may be one or more LEDs, one or more lasers, and / or one or more SLEDs (Super Luminescent LED). Preferably, the light source 1b has a different wavelength or a different wavelength range than the light source 1a. The light of the light source 1a and / or 1b is preferably used to irradiate a sample 50 to be examined. The light emitted by the light sources 1a and / or 1b can be changed by means of known optical means, for example by means of a lens 26 and / or a lens system (not shown) or an aperture (not shown) or a polarizing filter. Subsequently, the light of the light source 1a preferably passes through an excitation filter 25, preferably a bandpass filter, and the light of the light source 1b preferably passes through an excitation filter 24, preferably a bandpass filter. Preferably, the excitation filter 24 has a different transmission range than the excitation filter 25. Reference numeral 23 refers to an optional detector filter, for example a bandpass filter or a longpass filter or a shortpass filter or a dualpass or multipass filter. In the case of fluorescence, the filter 23 may also be referred to as an emission filter.

The light of the two excitation light sources is preferably combined, for example, reflected by the dichroic mirror 28 and then preferably by another dichroic mirror 29 in the direction of the object lens system 38. The dichroic mirror 29 is also preferably used to separate the excitation light from the detection light. After the reflection at the dichroic mirror 29, the excitation light preferably passes through another dichroic mirror 34 ("hot mirror") and is then preferably from the object lens system 38 through the transparent bottom 47 of the multiwell plate into the aqueous solution 50, in the sample chamber 45, preferably a " Well "a multiwell plate, focused. There, the excitation light excites the fluorescence of fluorescent particles 105, for example proteins with intrinsic fluorescence and / or fluorescence-labeled biomolecules or other fluorescent substances. The fluorescent light is collected by the object lens system 38, preferably a lens, a combination of lenses or a microscope objective, then passes through the dichroic mirrors 34 and 29, then the detection filter 23, preferably an emission filter, for example a bandpass filter, dual pass filter or multipass filter, and is then focused by a lens 17, for example an asphere, onto the detector 19, for example a photodiode, a PMT, a CCD camera, a CMOS camera, a diode array, an avalanche photodiode.

By means of this detector intensity and / or phase and / or timing of the fluorescence intensity can be measured and then processed and stored electronically.

The infrared radiation for generating the thermal convection is preferably generated by means of a fiber-coupled infrared laser 32. The fiber of the laser is coupled, for example by means of a fiber coupling 27, preferably with collimating functionality, in the optics or the optical system. The infrared radiation may be changed by known optical means, for example by means of a lens 26 and / or a lens system (not shown) or an aperture (not shown) or a polarizing filter. For example, it may be parallelized or focused by the lens 26, for example an asphere. Subsequently, the infrared radiation is mirrored by the dichroic mirror 34 ("hot mirror") in the object lens system 38. The object lens system 38 then focuses the infrared radiation 30 through the transparent bottom 47 of the multiwell plate into the aqueous solution 50 of the sample chamber 45, preferably a "well" of a multiwell plate. The multiwell plate is preferably a 96 well plate or 384 well plate or 1536 well plate. Depending on the focusing, the infrared radiation 30 generates a defined thermal convection 90 there for the mixing of the particles 105 in the aqueous solution 50.

The particles are, for example, biomolecules such as DNA, RNA, PNA, proteins, antibodies, antigens or small molecules, cells, viruses, bacteria, microbeads, nanobeads, nanoparticles, polymers, peptides. For example, the device can also be used for the detection and quantification of biomolecule aggregation, for example, the aggregation of proteins or therapeutic Antiköprern.

Claims (9)

1. A method for mixing liquids (50) or particles with a liquid (50), comprising the steps of:

   (a) providing a volume of liquid (50) in a microcavity of a 384-microwell plate or a 1536-microwell plate;

   (b) providing a plurality of IR LEDs;

   (c) generating a thermal convection flow at at least one boundary surface between the volume of liquid and the microcavity by simultaneously irradiating IR radiation (30) of the plurality of LEDs into a plurality of the cavities;

   wherein a depletion layer at the boundary surface is reduced or a concentration layer at the boundary surface is increased by the convection flow so that measurement methods based on the boundary surface are improved.
2. The method according to claim 1, wherein the liquid (50) is an aqueous solution.
3. The method according to any one of the preceding claims, wherein the radiation (30) is directed parallel and/or antiparallel to gravitation and/or comprises a component that is oriented vertical to gravitation.
4. The method according to any one of the preceding claims, wherein a temperature gradient of from 0.001 K/µm (= 1 K/mm) to 2 K/um (= 2,000 K/mm) is generated with the irradiated radiation (30).
5. The method according to claim 4, wherein a detection region (80) for measuring properties of the liquid or of the particles in the liquid is spaced apart from the area into which the radiation (30) is irradiated.
6. The method according to any one of the preceding claims, wherein flow rates of from 0.0005 mm/s to 2 mm/s are generated within the convection flow.
7. A method for analyzing molecular interactions at and/or in a thin film (80) in a volume of liquid by means of a measuring method based on a boundary surface, comprising the steps of:

   - providing, in a microcavity of a 384-microwell plate or a 1536-microwell plate, at least one volume of liquid (50) with particles present therein,

   - providing a plurality of IR LEDs;

   - irradiating IR radiation of the plurality of IR LEDs into volumes of liquid (50) of the plurality of microcavities of the multi-well plate for generating the thermal convection flow,

   - measuring a specific or unspecific interaction of the particles with a boundary surface of the microcavity by means of the measuring method based on the boundary surface;

   - characterizing the interaction of the particles on the basis of the measurement.
8. The method according to claim 7, wherein

   (i) the interaction is measured by means of reflectometric interference spectroscopy (RIfS);

   (ii) the interaction is measured by means of surface plasmone resonance (SPR);

   (iii) the interaction is measured by means of an enzyme linked immunosorbent assay (ELISA);

   (iv) the interaction is measured by means of a quartz crystal microbalance (QCM);

   (v) the interaction is measured by means of a surface acoustic wave (SAW); or

   (vi) the interaction is measured by at least one method from the group of: reflectometric interference spectroscopy (RIfS), bio-layer interferometry (BLI), surface plasmone resonance (SPR), quartz crystal microbalance (QCM), surface acoustic wave (SAW), enzyme linked immunosorbent assay (ELISA), nanopores or transistors (next generation sequencing).
9. An apparatus for the mixing of liquids (50) or of particles with a liquid (50), for performing a method according any one of claims 1 to 8, comprising:

   (a) a 384-microwell plate or a 1536-microwell plate for receiving a volume of liquid (50); and

   (b) a plurality of IR LEDs for emitting IR radiation (30);

   (c) a means for irradiating the IR radiation (30) into a plurality of volumes of liquid of the microwell plate.

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