Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
  • G01N21/51—Scattering, i.e. diffuse reflection within a body or fluid inside a container, e.g. in an ampoule
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
  • G01J3/28—Investigating the spectrum
  • G01J3/44—Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/02—Investigating particle size or size distribution
  • G01N15/0205—Investigating particle size or size distribution by optical means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1434—Optical arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
  • G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
  • G01N21/65—Raman scattering
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
  • G01N2021/4709—Backscatter
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
  • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
  • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
  • G01N21/80—Indicating pH value
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/061—Sources
  • G01N2201/06113—Coherent sources; lasers
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/06—Illumination; Optics
  • G01N2201/068—Optics, miscellaneous

Definitions

• the invention relates to methods and apparatus for detecting properties of suspended particles.
• an optical instrument for detecting properties of a sample comprising:
• a sample cell for holding a sample of a particulate dispersion
• a coherent light source configured to illuminate the sample in the sample cell
• a light intensity detector positioned to receive and measure an intensity of light from the coherent light source elastically scattered by the sample in the sample cell
• a spectral light detector positioned and configured to receive and measure a range of wavelengths of light from the coherent radiation source inelastically scattered by the sample in the sample cell.
• the spectral light detector may be a Raman detector.
• the coherent light source may be a laser.
• the light intensity detector may be a photon-counting detector.
• An attenuator may be positioned between one or more of:
• the sample cell and the light intensity detector are the sample cell and the light intensity detector.
• the attenuator may be configured to be switchable to provide in a first state a predetermined amount of attenuation for light received by the light intensity detector and in a second state a lesser amount of attenuation for light received by the spectral light detector.
• the light intensity detector may be configured not to detect light when the attenuator is in the second state.
• the optical instrument may comprise a filter configured to transmit a selected range of wavelengths of light from the coherent radiation source inelastically scattered by the sample in the sample cell to the spectral light detector.
• the filter may be a notch filter.
• the spectrometric detector may be configured to receive scattered light from the sample cell along a path orthogonal to incident light from the light source and/or along a path reverse to the incident light for detection of backscattered light.
• the coherent radiation source may comprise first and second coherent light sources and the light intensity detector may be responsive to light transmitted by the first coherent light source and the spectral light detector responsive to light transmitted by the second coherent radiation source. Both the light intensity detector and the spectral light detector may be configured to receive and measure light during a measurement period while a property of the sample in the sample cell changes.
• the property may for example be one or more of pH and temperature.
• a method of detecting optical properties of a sample of a particulate dispersion comprising: positioning the sample in a sample cell for analysis;
• the sample may be excited with light from a common coherent radiation source during detection of both elastically and inelastically scattered light from the excited sample.
• the step of exciting may involve exciting the sample with different coherent radiation sources during the step of detecting elastically scattered radiation and the step of detecting inelastically scattered radiation from the sample.
• the step of exciting the sample may be repeated while a condition of the sample is changed.
• the method may further include the step of performing a correlation between results of the step of detecting elastically scattered radiation from the excited sample and results of the step of detecting inelastically scattered radiation from the excited sample while the condition is changed.
• the condition may for example be temperature or pH.
• the method may further include the step of associating a change in a chemical property of a species in the sample with a changes in the condition based on results of the steps of detecting elastically scattered radiation from the excited sample and detecting inelastically scattered radiation from the excited sample.
• the steps of exciting and detecting may be repeated to evaluate one of manufacturability, stability, shelf life, quality control, quality assurance or formulation of the sample.
• the steps of positioning, exciting, detecting and removing may be performed for a protein suspension, a biopharmaceutical or for one or more of an enzyme, a protein, a DNA sequence, an RNA sequence, a vaccine, a virus and a virus-like particle.
• the method may further including the step of deriving a physical property of the sample from the detected elastically scattered radiation and the step of deriving a chemical property of the sample from the detected inelastically scattered radiation.
• the step of deriving a physical property may include deriving a particle size or polydispersity value and the step of deriving a chemical property includes deriving a measure of chemical identification or molecular structure.
• the steps of positioning, exciting, detecting and removing may be performed for a protein, and the step of deriving a physical property may include deriving a protein aggregation size distribution and the step of deriving a chemical property may include deriving a protein secondary and tertiary structural information from a Raman measurement.
• the step of deriving a chemical property may include deriving information about protein folding or protein denaturation/renaturation.
• Systems according to the invention can provide a significant amount of structural and chemical information about nanoparticles and other nanomaterials such as larger proteins at a lesser expense that some of the more expensive X-ray crystallography and multidimensional Nuclear Magnetic Resonance (NMR) instruments. This can come at the price of a relatively simple add-on to an existing DLS/SLS system.
• the dual-mode instrument can use a single radiation source to obtain complementary information about both elastic and inelastic scattering.
• an optical instrument for detecting properties of a sample comprising: means for holding a sample for analysis,
• an optical instrument for detecting properties of a sample comprising:
• one or more coherent radiation sources positioned to illuminate the sample in the vessel
• At least one spectral detector positioned to receive light from the coherent radiation sources inelastically scattered by the sample in the vessel.
• a method of detecting optical properties of a sample comprising:
• the step of performing an inelastic spectral measurement on the sample may include performing a Raman measurement.
• an optical instrument for detecting properties of a sample comprising:
• one or more coherent radiation sources positioned to illuminate the sample in the vessel
• At least one photon-counting detector positioned to receive light from the coherent radiation sources elastically scattered by the sample in the vessel
• a method of detecting optical properties of a sample comprising:
• figure 1 is a block diagram of a prior art DLS/SLS measurement system that can be used as the basis for an illustrative system according to the invention
• figure 2 is a block diagram of an illustrative embodiment of a dual-mode scattering system according to the invention based on the DLS/SLS measurement system of figure 1 ;
• figure 3 is an illustrative Raman spectrum for a 50mg/ml solution of BSA at 61 ° C obtained with the system of figure 2;
• figure 4 is an illustrative size distribution plot for the 50mg/ml solution of
• figure 5 is an illustrative combined plot of Raman and DLS size measurements for a range of different temperatures obtained with the system of figure 2;
• figure 6 is a block diagram of an illustrative embodiment of a dual-mode scattering system according to an alternative embodiment based on a laser diffraction measurement system;
• figure 7 is a graph showing plots of z-average radius and Raman Amide III intensity ( 1297 cm “ 1 ) as a function of pH for a sample of BSA during a titration
• figure 8 is a plot of Raman shift measurements and a correlation with DLS size measurements for a BSA 10 mg/ml solution
• figure 9 is a plot of Raman intensity as a function of Raman shift for 10 mg/ml solutions of BSA and IcG; and figure 10 shows plots of Raman intensity as a function of Raman shift for BSA (figure 10a) and IgG (figure 10b) solutions, together with correlations with DLS polydispersity and size.
• Systems according to the invention can be built from the ground up or may be based on a pre-existing off-the-shelf optical instrument. Such a system can be based on an optical instrument 100 such as the Zetasizer nano particle measurement system, which is outlined schematically in figure 1.
• the Zetasizer particle measurement instrument line is available from Malvern instruments Ltd of Malvern, UK and is described in further detail in WO 2010/04182, the contents of which are incorporated herein by reference.
• the particle measurement system 100 includes a coherent radiation source 101 , such as a laser.
• the output of this laser 101 is provided to an attenuator 102, optionally via one or more intervening reflectors 1 10a, 1 10b, through a sample cell 103, and on to a transmission monitor 104.
• Classical 90° optics 106 and/or backscatter optics 105 receive scattered radiation from a suspended particulate sample in the sample cell 103 and measure an intensity of light received from the light source 101 and elastically scattered by the sample in the sample cell 103.
• the received scattered radiation for one or both of these sets of optics 105, 106 can then be relayed via an optical fiber 107 to an Avalanche Photo Diode (APD) 108.
• APD Avalanche Photo Diode
• one approach to modifying the system 100 of figure 1 to achieve dual-mode detection in accordance with an aspect of the invention is to add a dielectric filter 21 1 in the backscatter path.
• This dielectric filter 21 1 relays longer wavelength light to a spectrometric detector 212, such as a Raman detector.
• the Raman detector 212 can include one or more laser notch filters 213, a diffraction grating 214, and a dimensional detector 215, such as a Charge Coupled Device (CCD).
• CCD Charge Coupled Device
• Raman detection is shown in figure 2 to take place in the backscatter path, it can also or alternatively take place from one or more of a number of different angles including from a pickoff point 216 in the classical 90° path.
• the spectrometric detector 212 may be configured to receive scattered light from the sample cell along a path orthogonal to the incident light and/or along a path reverse to the incident light for detection of backscattered light.
• the laser 101 in the system 200 of figure 2 is used for both DLS and Raman measurements.
• the attenuator 102 is turned on so that the APD 108 (figure 1 ) is not saturated.
• the attenuator 102 is turned off to allow the high level of illumination used in Raman measurements.
• the system 200 can acquire information about both elastic and inelastic scattering. These two types of detection can provide complementary information about a particular suspension. For example, DLS measurements can provide information about the aggregation of particulates, while Raman measurements can provide information about the cause of the aggregation or whether the structure of individual particles has changed.
• the instrument 200 can also be used to compare one particulate suspension with another. This may be useful for example when comparing one biopharmaceutical formulation from one company with a biosimilar manufactured by another company.
• a system can be built with separate sources for the different measurements organized around separate optical paths.
• the system can also employ a different arrangement of optical elements and/or different selective or switching elements, such as moving mirrors or choppers, to make both types of measurements.
• the attenuator 102 can be placed in the fiber optic 107 path, allowing DLS and Raman measurements to be taken simultaneously.
• the system 200 of figure 2 can be operated to provide spectral information, such as a Raman spectrum 301 (figure 3) and physical property information, such as a size distribution 401 (figure 4) for the same sample at effectively the same time. These measurements can also be taken in succession under different conditions, such as sample temperature, concentration, pH or composition.
• Figure 5 illustrates plots of DLS average size data 501 (left hand scale, in nm) and Raman shift data 502 (right hand scale, in cm " 1 ) as a function of temperature (in °C) for a protein solution.
• both the light intensity detector and the spectral light detector are configured to receive and measure light during a measurement period while a property of the sample in the sample cell changes.
• the property of the sample may be deliberately changed, such as by changing the pH or temperature of the sample, or may change as a result of an ongoing reaction while the sample is being measured.
• the advantage of such dual measurements is therefore clear, in that different measurements can be taken on the same sample over the same measurement period by alternating between DLS and Raman measurements.
• the measurements can be performed manually, or may alternatively be performed automatically using standard robotic loading systems, such as x-y stages or using automated pipetting systems.
• the optical instrument system may be implemented in connection with special-purpose software programs running on general-purpose computer platforms, in which stored program instructions are executed on a processor.
• the system could also be implemented in whole or in part using special-purpose hardware to achieve the same function. While the system can be broken into the series of modules and steps shown for illustration purposes, one of ordinary skill in the art would recognize that it is also possible to combine them and/or split them differently to achieve a different breakdown.
• Another approach to dual-mode characterization of particulates is to perform simultaneous Raman and laser diffraction measurements.
• the technique of laser diffraction is based around the principle that particles passing through a laser beam will scatter light at an angle that is directly related to their size. As the particle size decreases, the observed scattering angle increases logarithmically. The observed scattering intensity is also dependent on particle sizes and diminishes, to a good approximation, in relation to the particle's cross-sectional area. Large particles therefore scatter light at narrow angles with high intensity, whereas small particles scatter at wider angles but with low intensity.
• the primary measurement that is carried out within a laser diffraction system is the capture of the light scattering data from the particles under study.
• Systems according to this aspect of the invention can be built from the ground up or they can be based on a pre-existing off-the-shelf instrument.
• a system can be based on the Mastersizer 3000 particle size analyzer, which is available from Malvern instruments Ltd of Malvern, UK.
• An exemplary system 300 illustrated schematically in figure 6, comprises a coherent light source such as a red laser 601 with an optional attenuator 602, for providing a source of coherent, intense light of a fixed wavelength.
• An optional second coherent light source such as a blue laser 621 may also be provided.
• the system 300 further comprises a sample presentation system such as a sample cell 603 configured to pass a material under test through the incident laser beam, preferably as a homogeneous stream of particles 604 in a known, reproducible state of dispersion.
• a first series of detectors including a focal plane detector 605a and an array of large angle detectors 605b, are provided to measure the light pattern produced over a wide range of angles by scattering of incident light by the dispersed particles in the sample cell 603.
• a second series of detectors 606, 612 are provided to measure backscattered light from the sample cell 603 and for Raman detection.
• a dielectric filter 61 1 may be placed in one of the backscattered light paths, the filter 61 1 configured to relay longer wavelength light to a spectrometric detector such as a Raman detector 612.
• the Raman detector 612 can include one or more laser notch filters 613, a diffraction grating 614, and a dimensional detector 615, such as a Charge Coupled Device (CCD).
• CCD Charge Coupled Device
• Raman detection is shown to take place in one of the backscatter paths, it can also or alternatively take place from one or more of a number of different angles including from a pickoff point in the classical 90° path, as in the embodiment of figure 2 described above.
• the laser 601 (and/or 621 ) in the system 300 of figure 6 is used for both laser diffraction and Raman measurements.
• the attenuator 602 is turned on so that the scattering detectors are not saturated.
• Raman measurements the attenuator 602 is turned off to allow the high level of illumination used in Raman measurements.
• the laser diffraction measurements can provide information about physical properties of the sample, while the Raman measurements can provide information about the chemical makeup of the sample.
• the Raman measurements can provide information about the chemical makeup of the sample.
• a system can be built with separate sources for the different measurements organized around separate optical paths.
• the system can also employ a different arrangement of optical elements and/or different selective or switching elements, such as moving mirrors or choppers, to make both types of measurements.
• the attenuator 602 can be placed in such a way as to allow laser diffraction and Raman measurements to be taken simultaneously.
• the size range accessible during the measurement is directly related to the angular range of the scattering measurement.
• Modem laser diffraction instruments make measurements from around 0.02 degrees through to 135 degrees.
• a logarithmic detector sequence where the detectors 605 are grouped closely together at small angles and more widely spaced at wide angles, yields the optimum sensitivity.
• the detector sequence can also be set up such that equal volumes of particles of different sizes produce a similar measured signal. With this approach, the size of the detectors is increased as the measured scattering angle increases.
• FIG. 10a illustrates a plot of Raman measurements 1001 a and correlations with DLS polydispersity 1002a and size 1003a for BSA
• figure 10b illustrates Raman measurements 1001b and correlations with DLS polydispersity 1002b and size 1003b for IgG.
• These correlations can be matched with corresponding molecular features to determine which features are likely to have been affected by the physical changes. Using this technique it can be shown, for example, that a protein denatures and/or aggregates differently in response to changes in temperature than it does in response to changes in pH.
• Raman measurements could be used to detect crystallinity of a sample and laser diffraction used to detect size of the sample, while a condition of the sample is varied. This may allow a deeper understanding of the degree to which a sample exhibits crystalline, amorphous, and/or polymorphic properties in different conditions. With this type of understanding, it is possible to perform Raman measurements to learn information about physical properties of a sample in a particular system, such as size, shape, diameter, or aspect ratio.
• DLS Dynamic Light-Samiconductor
• physicochemical properties such as the protein zeta potential, charge or isoelectric point.
• This cross-measurement principle can be used between any types of measurements in a dual-mode system according to different schedules.
• a quality control situation for example, a material under test might be fully characterized with both measurement techniques, but routine testing might then be performed with only one of them.
• the selected technique for routine testing might be selected for a variety of reasons, such as because it is less expensive, quicker, more scalable, or more reliable.
• Systems according to the invention can be applicable to a wide variety of applications, including research, quality control, formulation development, stability testing, manufacturability testing, efficiency testing, release testing, and drug discovery. They are also applicable to a wide variety of materials, such as biopharmaceuticals, small- and large-molecule proteins, excipients, and pigments and other industrial powders.

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• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)

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• 2012
  • 2012-08-17 EP EP12775275.6A patent/EP2742337B1/en active Active
  • 2012-08-17 US US14/239,039 patent/US9816922B2/en active Active
  • 2012-08-17 WO PCT/GB2012/052019 patent/WO2013027034A1/en not_active Ceased
  • 2012-08-17 CN CN201280040414.6A patent/CN103748450A/zh active Pending
  • 2012-08-17 JP JP2014526551A patent/JP2014524581A/ja active Pending

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