ITRM20110438A1 - PROCEDURE FOR THE REALIZATION VIA PLASMA OF NANOMETRIC THICKNESS COATS THAT ALLOW THE CONTROLLED RELEASE OF SILVER IONS OR OTHER ELEMENTS, OR MOLECULES OF BIOMEDICAL INTEREST, SOLID PRODUCTS, AND SO COATED PRODUCTS. - Google Patents

Description

Process for the realization via plasma of nanometric thickness coatings that allow the controlled release of silver ions or other elements, or molecules of biomedical interest, from solid products, and thus coated products

The present invention relates to the realization of nanometric thickness coatings, possibly multilayer, with release properties of ions, drugs, compounds or antibacterial molecules, compounds or molecules of other types of interest in medicine and biology (such as growth factors , antibiotics, contraceptives, antithrombotic drugs, hormones, etc.), and superficial properties of biomedical interest (such as, for example, hydrophilic or hydrophobic, the ability to discourage or promote the adsorption of biomolecules, biological cells and tissues, increase or decrease lubricity ), modular, controllable and perfectly independent from each other, designed to improve the performance of medical or commonly used devices.

For reasons of clarity, it is specified that in the following the terms "layer", "coating" and "film" are adopted with the same meaning as "coating". Furthermore, it should be noted that the layer containing the substance to be released is referred to as the "matrix", while the layer that controls its release is referred to as the "barrier". The generic term "reserve" means all the material or layer containing the molecule or atoms subject to the release. Finally, it should be noted that the term "substrate" can indicate both the support on which the multilayer according to the invention is applied and the substance to be released on which only the barrier layer is applied. In the present invention, the term "precursor" indicates the feed gas of the chemical plasma deposition processes.

In US 2009/0035341 Al a barrier layer is obtained, by plasma polymerization, on an underlying matrix layer of only biocidal substance to be released, for example of only silver. In WO 2010 / 084351A1, on the other hand, there is no barrier layer, from plasmochemical deposition, overlying the matrix layer that incorporates the antimicrobial substance to be released, for example silver.

A scheme of the possible configurations of the multilayer is shown in figure 1, which shows examples where the substance to be released is in the form of free particles, or included in the substrate or dispersed in a coating deposited on it, or in the form of a deposited coating. on the substrate, or constitutes the substrate itself.

Silver, as an example of a substance to be released, has a broad spectrum of action against bacteria, viruses, molds and spores; in the case of multilayer coatings containing silver, the antibacterial properties derive from the release of Ag <+> ions from the layer adhering to the substrate, a release that can be dosed. Other metals or oxides, such as copper, zinc, titanium dioxide (TiO2), titanium, gold, carbon, gallium, as well as various types of organic substances, including antibiotics, have antibacterial properties similar to silver.

The surface properties of biomedical interest (e.g. stimulation or inhibition of cell adhesion) of the multilayer pertain to the surface of the outer layer of the coating, and can be predetermined, for example to favor or discourage the adsorption of biomolecules and / or the adhesion of cells and tissues. In the first case we will talk about celi- and / or protein-adhesive coating, in the second case of unfouling film. The ability to control the released quantity of silver or other substances included in the multilayer is also attributed to the outer layer.

All the external layers capable of modulating the release, object of the present invention, are made by means of "cold" plasmas; the substrate and the internal layers of the multilayer can be made via plasma, or in another way, depending on the application.

Plasma is a partially ionized gas, rich in active species (eg atoms, ions, electrons, radicals) generated by fragmentation, ionization and recombination of molecules, atoms, ions of the starting gas, through the application of energy (eg. heat, or electromagnetic fields). The state of plasma, present in nature (e.g. stars, flames, lightning, northern lights), can be artificially produced in equilibrium conditions (e.g. welding plasmas, torches for waste incineration) or non-thermodynamic equilibrium (e.g. neon lamps, plasma TVs, etc.). In the first case we speak of "hot" plasmas, characterized by very high temperatures, even around 10,000 K. of interest for the treatment of materials in various applications, including those in the biomedical field.

In suitably configured reactors it is possible to expose the materials to cold plasmas, modifying their surface in processes of: etching (chemical ablation of the material); thin film deposition (PE-CVD, Plasma Enhanced-Chemical Vapor Deposition), - treatment (grafting, grafting of chemical groups to the substrate surface); sputtering (physical ablation of the material). Using cold plasma it is possible to treat in a very versatile way conventional thermolabile materials, such as polymers, paper, leather and fabrics. By varying the experimental parameters (e.g. nature and flow of the supply gas / steam, pressure, power, etc.), the surface chemical / physical properties of the materials can be varied (e.g. hydrophobic / hydrophilic character, biocompatibility, etc.) , leaving its massive structure and properties unaltered. This represents an indisputable advantage for materials of biological interest (e.g. prostheses, biosensors, devices, etc.) for which the interactions with the host organism or with biological fluids are mainly localized at the material / environment interface. biological.

The plasmochemical processes make it possible to modify the chemistry and properties of the most superficial layers of materials at room temperature, leaving their massive structure and composition unaltered. Other advantages are: the versatility, the absence of solvents, the minimum quantity of reagents, the negligible environmental impact, the low cost of the process, the possibility of scaling the processes on large products, and the integration into production lines. .

Coatings deposited in plasmas fed with volatile monomers characterized by Ethylene Oxide (-CH2CH2O-, EO) units, can exhibit chemical structure similar to Polyethylene Oxide (PEO) or PolyethyleneGlycol (PEG) polymers, and for this reason they are called PEO-like. The concept of "PEO-like" film is extended in this invention to films that have a percentage of ether groups measurable with the X-rays Photoelectron Spectroscopy (XPS) technique comprised between 10% and 100%, therefore also very far in composition. chemistry from PEO and PEG polymers. Due to their great affinity with water, PEO-like films with a percentage of ether groups between 65% and 100% referring to all the other carbon functionalities (carboxyl, carbonyl, alcohol, etc.) behave like hydrogels and discourage , in vitro, protein adsorption, cell adhesion and biofilm formation (unfouling effect).

By feeding the plasma with gases / vapors of other substances, it is possible to deposit coatings of a different nature, which can also be used to modulate the release of substances from substrates of biomedical interest and, at the same time, to modulate their surface properties.

Via plasma it is also possible to deposit nano composite coatings in which, that is, particles (clusters) of silver, other metals, oxides of the same or other compounds (e.g. hydroxyapatite) of nanometric dimensions are dispersed in matrices not necessarily of a PEO-like nature but also of another organic and inorganic nature. Coatings containing clusters of silver dispersed in a PEO-like matrix, called Ag / PEO-like, in aqueous environment release Ag + ions, with a proven antibacterial effect, for example against bacteria particularly resistant to common antibiotics, such as Pseudomonas aeuriginosa and Staphilococcus epidermidis.

In addition to the aforementioned antibacterial activity, it is also possible to deposit, for example on medical devices or structures known as scaffolds, coatings in which hormones, drugs, proteins and anything else may be able to interfere in biological processes, controlling their release and thus modulating its effects.

The present invention allows to modulate the released quantity of silver ions or other ions or other substances, and the consequent effects of biomedical interest. For example, the blocking of the receptors for the various growth factors (epithelial, vascular, nervous) or, on the contrary, the stimulation of said receptors. The field of application is therefore infinite, or at least as vast as the knowledge on possible interactions with living matter.

In the case of ions or other antibacterial substances, the barrier layer allows to take advantage of the properties of the substance, but to reduce the possible cytotoxic effect of some of them, for example silver ions, towards eukaryotic cells. Furthermore, since the barrier film is deposited via plasma, its chemical-physical characteristics can be varied in a targeted and simple way by modifying the deposition parameters and, therefore, giving the film itself variable biological and barrier properties, peculiar to the process. used and also completely different from those of conventional materials on the market.

In the case of Ag / PEO-like and PEO-like coatings, these were deposited via plasma on various substrates, including devices of biomedical interest, in a radiofrequency chemical plasma reactor (RF, 13.56 MHz). To deposit Ag / PEO-like films in this reactor, one works in conditions that ensure, at the same time, the sputtering of atoms and clusters of silver from the target electrode of the reactor, and the deposition, on the other electrode, of a PEO coating. -like that encompasses clusters of silver. The two-electrode configuration can be replaced by one to three or more electrodes, depending on process or application needs. Under optimized conditions, as the power increases and the working pressure and precursor flow decrease, the degree of crosslinking of the PEO-like matrix, the size of the clusters and the total quantity of silver incorporated increase. Increasing the deposition time increases the thickness of the coating. The silver content of the coatings can be measured, for example as an atomic percentage on the elements Ag, C and O, with the XPS technique. By varying the material of the target electrode and the precursor, therefore the nature of the clusters and the organic matrix, it is possible to deposit other types of nano composite coatings, for example containing clusters of other metals such as copper or zinc, or of oxides, such as bi - titanium oxide.

The Ag / PEO-like coating constitutes the silver reserve on the surface of the coated device; the thickness of the coating can vary from 10 nm to several microns (up to 50 mi-cron), according to the needs. The release of Ag + ions occurs in an aqueous environment and is a function, among other things, of the quantity of silver incorporated in the coating and of the chemical nature of the matrix in which the clusters are incorporated. Measurements of silver release in cell culture media by Ag / PEO-like coatings were conducted by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), as shown in Figure 2. The measurements showed that the rate of recovery left in aqueous media it gradually decreases over time, and varies according to the chemical nature of the coating matrix, the quantity of silver incorporated, and the thickness. By appropriately choosing the deposition parameters of the Ag / PEO-like coating, it is possible to control: the quantity of silver incorporated; the degree of crosslinking of the PEO-like organic phase in which the silver is finely dispersed; and the size of the silver clusters. According to the characteristics of the deposited film, the antibacterial effect can therefore be modulated by acting on the quantity of silver incorporated and thus offering various technological solutions depending on the area of application of the device thus coated.

The release mechanism of silver ions follows the typical kinetics of a matrix-type drug release system. It is assumed that silver diffuses first through the water-soaked PEO-like matrix, until it reaches the biological material / environment interface first, and then the aqueous medium. This mechanism is affected by the degree of cross-linking of the matrix, the quantity of silver in the coating, and the size of the clusters. Films containing very high amounts of silver, for example, can release silver ions in an uncontrolled way.

The coating containing silver, or other bioactive substances, can also comprise a matrix other than the PEO-like described above, for example of the silicone type, silicon oxide (SiOx), fluorocarbon (CFx), hydrocarbon (CHx), acrylic COxHy), or other type, not necessarily produced via plasma.

The ions and substances that act against bacteria can also have a slightly cytotoxic effect, especially if in a locally high concentration, higher than that (minimum inhibitory concentration) which guarantees the antibacterial effect (0.5-10 mg / l in the case of Ag + ions).

The present invention, therefore, concerns the application of a coating with barrier effect, for example of the PEO-like type, with a thickness (5 - 10,000 nm) and a controlled chemical composition, above the Ag / PEO-like coating, or in any case of the coating or substrate containing the bioactive substance (s) to be released. In the specific case of multilayer film with PEO-like barrier on Ag / PEO-like film, varying with the deposition parameters the density of the EO units (therefore the crosslinking of the PEO-like matrix, measurable at XPS) in the PEO- coating like, it is possible to modulate the release of Ag + ions, or of other substances; moreover, the adsorption of proteins and the adhesion of eukaryotic cells on the coating can also be modulated. A highly cross-linked PEO-like coating (low density of EO units) will significantly decrease the quantity of silver ions released and will favor the adsorption of proteins, the adhesion of cells and tissues on the coated device; if poorly cross-linked (high density of EO units), on the other hand, the coating will discourage the adsorption of biomolecules and the adhesion of cells (unfouling effect).

The deposition of the PEO-like coating can be carried out in the same reactor, immediately after the deposition of the Ag / PEO-like coating, in conditions that prevent the sputtering of the silver, for example: replacing the silver electrode with an inert one (eg , steel), or by increasing the working pressure, or by shielding the target electrode with a screen (shutter). As the power decreases, the precursor flow in the feed mixture increases, and the pressure increases, the quantity of EO units in the PEO-like coating increases and therefore its unfouling character; increasing the deposition time increases the thickness of the coating.

One of the most important advantages of the barrier coatings object of the present invention is that, for example in the case of nano composite coatings containing silver, they allow to modulate the quantity of silver released in situ by the nano composite coating, so as to still be effective against bacteria, but not cytotoxic to eukaryotic cells. To obtain other surface properties, the barrier coating deposited via plasma could be, for example, silicone, silicon oxide (SiOx), fluorocarbon (CFx), hydrocarbon (CHx), acrylic COxHy), or other types.

The antibacterial efficacy of Ag / PEO-like films has been tested on Pseudomonas Aeruginosa and Staphilococcus Epidermis bacterial lines. In the first case, using a bacterial adhesion test (4xl0 <7> cell / ml, under stirring), it was observed that films containing 3.5% silver reduce the adhesion of bacteria by 100% after 2 hours of incubation compared to to untreated substrates, metals and polymers and ceramics, of various types. In experiments conducted with the species S. epidermidis ATCC 35984 (3X10 <8> CFUs / ml) both in static and dynamic conditions (flow chamber with flat and parallel plates), after 2 hours of incubation it was observed that films containing the 24.4% of silver kill 80% of bacteria adhering to the surface of the substrates.

The present invention, on the other hand, allows to realize a multilayer coating with controlled release of silver ions, uniform and lasting in a humid environment, by exploiting the barrier film. The multilayer film is made entirely via plasma with a multi-stage process. The invention also allows to moderate the release over time so as to reduce or eliminate the cytotoxic effect of silver, while retaining its antibacterial effect.

The invention is based on plasma deposition, as a single synthesis method, of the barrier film: the process therefore guarantees high versatility of application both because it is independent of the nature of the coated material, and because the antibacterial properties (or in general release), unfouling and biocompatible of the multilayer can be varied independently. In fact, the subject of the present invention is a process for manufacturing, or restoring, bio-medical instruments or devices (such as prostheses, catheters, intraocular lenses, filters for hemodialysis, heart valves, syringes and other medical devices) and on commonly used items (such as filters for air conditioning systems, toothbrushes, long-lasting razor blades, fluid circulation tubes), by plasmochemical way, of an organic or inorganic film possibly with a structure similar to polyethylene oxide (PEO-like) and with antibacterial properties, or with the possibility of release for medical devices also of drugs or compounds having other types of action (therapeutic, hormonal, etc.) characterized by the fact that the deposited film is multi-layered and ̈ essentially obtained with the following operations:

- Deposition via sputtering of a silver target (or of other metals or bioactive oxides} and PE-CVD, contamporanei, of a first inorganic or organic layer, possibly with a PEO-like matrix, inside which clusters of the metal are incorporated;

deposition via PE-CVD of at least a second organic or inorganic layer, possibly PEO-like, with chemical characteristics and thickness suitable for containing and controlling the release of silver ions.

The resulting multilayer will therefore be able to control and make the release of antibacterial ions Ag <+> (or other ions or compounds with an antibacterial effect, or any other substance for which an effective concentration is required to be reached) uniform and lasting. to exert a therapeutic effect) in humid environments thanks to the chemical nature and thickness of the barrier layer (cross-linked and / or thick films reduce release). The quantity of silver released also depends on the total quantity of silver incorporated in the composite nano film and on its thickness.

The plasmochemical depositions reported for the present invention were carried out with reactors fed with an alternating electric field at a frequency of 13.56 MHz. In this case, the first layer can be obtained with exposure to the sputtering / PE-CVD process for a sufficient time to produce a nano composite coating with a thickness between 5 nm and a few microns. Similar experiments can be conducted with plasmas obtained by feeding the plasma with sources at lower frequencies (tens-hundreds of KHz) and higher than 13.56 MHz, always obtaining similar performances.

The layer or layers subsequent to the one containing silver can be obtained with plasma exposure for a time sufficient to achieve a suitable thickness, under experimental conditions such as to control the chemical nature and degree of crosslinking of the film. It is also possible to create coatings with a chemical composition gradient (e.g. more cross-linked at the beginning of the process, less cross-linked at the end), or more layers of a completely different chemical nature, multifunctional (e.g. antibacterial / unfouling ; antibacterial / cell-adhesive; antibacterial / hydrophobic, etc.).

More generally, the present invention relates to a process for the realization, or the restoration, by plasmochemical way of a barrier film, possibly multilayer, which allows to carry out the release of substances of interest from a substrate in a controlled, uniform and long-lasting way. which includes the substance to be released as micro / nano particles, or from a layer deposited on the substrate which includes the substance to be released as micro / nano particles, or from a layer of substance to be released deposited on the substrate, or from a substrate which is the substance to be released possibly in the form of particles, in which the substance to be released is chosen from the group comprising metals and compounds with antibacterial properties and biologically active molecules, such as drugs, hormones, plant extracts, oligopeptides, lipids, proteins and glycides; the layer with the substance to be released is obtained by depositing a layer, inorganic or organic, possibly with a structure similar to polyethylene oxide polymers (PEO-like); the barrier film is obtained by depositing at least one preferably polymeric, inorganic or organic layer, possibly with a structure similar to polyethylene oxide polymers (PEO-like); and the substrates on which the deposits are made are medical-surgical devices, commonly used products, structures known as scaffolds and the substances to be released themselves.

The present invention is not limited to the process described above but extends, in addition to combinations of plasmochemical processes different from those mentioned so far, also to the coated products resulting from the execution of the process. Therefore, the subject of the invention are also medical-surgical devices, commonly used products and scaffolds coated with the layer containing the substance to be released and at least one barrier layer, as well as biologically active substances with at least one layer. barrier.

In the process according to the invention, the precursors of the plasma deposition process of the barrier coating can be: gases or vapors of non-oxygen containing precursors such as alkanes, alkenes and alkynes; gases or vapors of non-plasma polymerizable oxygen-containing compounds such as O2, CO2 and H2O alone or mixed with polymerizable precursors, compounds containing oxygenated groups, for example with structure CH3- (OCH2CH2) n-OCH3, ethers, corona ethers, or glycols , alcohols, carboxylic acids such as acrylic acid, aldehydes, anhydrides, ketones, phenols; gases or vapors of non-plasma polymerizable nitrogen-containing compounds such as, for example, N2, NH3 to be used alone or mixed with other plasma polymerizable precursors; plasma polymerizable volatile precursor vapors such as, for example, primary, secondary and tertiary amines and amides such as for example allyl amine, diaminocyclohexane, N-isopropylacrylamide; silicon-containing precursors such as silanes, organic silanes, siloxanes, and silazanes.

Figure 1 schematically shows the possible embodiments of the multilayer according to the invention which are:

A <)> The substrate includes the substance to be released through the barrier coating as micro / nano particles;

B <)> The substance to be released through the barrier coating is included as micro / nano particles in a coating deposited on the substrate;

C <)> The substance to be released through the barrier coating is in the form of a coating deposited on the substrate;

D) The substrate constitutes the substance to be released through the barrier coating;

E) The barrier coating is deposited directly on the particles of the substance to be released.

Figure 2 reports ICP-MS measurements of silver ion release by comparable cross-linked Ag / PEO-like coatings (% EO between 20 and 40%) and silver content (XPS) equal to 1%, 3% and 5%. Coatings containing more silver release larger amounts of silver ions over time.

Figure 3 shows the bactericidal effect ("zone of inhibition test") against Staphylococcus epidermidis RP62A ATCC 35984 (slime producer, Gram), of PET substrates coated with Ag / PEO-like PEO40% Agl% film, ie with the PEO-like matrix composed of 40% EO units, and containing 1% silver. Some substrates are covered with PEO-like barrier coatings with different composition (70%, 40%, 20% EO) and thickness (60 nm and 15 nm), which modulate the antibacterial effect.

Figure 4 reports ICP-MS measurements of silver ion release by 5% silver Ag / PEO-like coatings covered by two PEO-like barrier coatings with different cross-linking (EO 40% and 20%) and different thickness ( 15 nm and 60 nm). As the thickness and crosslinking of the barrier coating increases, the release decreases.

As has already been said, Figure 3 shows the bactericidal effect, measured with the zone of inhibition test, of polyethylene terephthalate (PET) substrates coated with Ag / PEO-like PEO 40% Agl% film, i.e. with the PEO matrix -like composed of 40% EO units, and containing a low quantity of silver, 1%, in order to demonstrate efficacy even at low release levels. Some substrates are covered with PEO-like barrier coatings with different composition (70%, 40%, 20% EO) and thickness (60 nm and 15 nm), which modulate the antibacterial effect.

The data in figure 3 show that the substrate as it is (PET T.Q.) and the PEO40% barrier coating obviously do not have an antibacterial effect. The PEO40% Agl% 80nm thick coating without barrier coating shows the maximum antibacterial effect, measured by an inhibition zone of more than 5 mm after 72 h of incubation at 37 ° C. The test was continued for a week, to check for any late effects. When the PEO40% Agl% film is covered with a barrier coating, the inhibition zone is reduced, reflecting the reduced release of silver ions, as the PEO matrix increases crosslinking (the lower the PEO% value, the greater the crosslinking) of the film barrier, and its thickness. The ICP-MS data in Figure 4 confirm that the release of Ag + ions from the Ag / PEO-like coatings can be modulated as a function of the cross-linking and the thickness of the PEO-like barrier layer.

EXAMPLE 1

The reactor, used for the depositions, for example of the present invention, is essentially constituted by a single reaction chamber in stainless steel, connected to the feeding and control equipment, such as:

â – ¡means to realize the vacuum;

â – ¡pressure reading system inside the reaction chamber (eg Baratron);

â – ¡radio frequency generator (RF, 13.56 MHz);

â – ¡an impedance adapter (matching network);

â – ¡feeding means of chemical substances (which include the precursor reserve), of reactants in the gaseous state, or of vapor, to the reaction chamber;

â – ¡a silver flat electrode replaceable with a stainless steel electrode (or totally shieldable in the presence of a third electrode), connected to the radio frequency generator, partially shielded by the shield connected to earth and water-cooled with the device, inside the reaction chamber, which also ensures the sputtering of silver, smaller than the one connected to the ground (ground electrode);

â – ¡a ground electrode, flat, inside the reaction chamber, on which the medical-surgical devices or items of common use to be treated are positioned.

The present reactor could also be equipped with two or more target electrodes for the simultaneous sputtering of other bioactive metals or oxides on the surface of the material of interest. All target electrodes in this case should be replaceable with inert electrodes such as steel ones or totally shieldable with the use of shutters.

The use of such a reactor used for the films shown for example of the present invention does not preclude the use of other plasmochemical methods and not for obtaining materials or layers that are able to act as "reserves" for controlled release of bioactive molecules or atoms. For example, magnetron reactors, plasma spray systems, atmospheric pressure plasmas could be used.

EXAMPLE 2

The invention provides for the deposition of a coating consisting of two or more superimposed organic or inorganic layers, the first of which contains clusters of metals or bioactive oxides (e.g. silver), while the subsequent layers have only a barrier effect or also other effects such as unfouling effect, increased biocompatibility, variation of the friction coefficient or effects that can be controlled with specific stimuli such as variations in temperature or pressure or acidity of the medium (smart materials). The process for depositing the films shown for example of this invention provides for the following steps:

a) preparation and introduction of biomedical devices (such as for example prostheses, catheters, intraocular lenses, filters for hemodialysis, parts of biosensors) or of commonly used items (such as filters for air conditioning, toothbrushes teeth, blades for long-lasting razors) on special trays arranged in different parts of the reactor (floating) or directly on the ground electrode;

b) formation of process vacuum in the reaction chamber (<10 <-3> Torr);

c) check that there is no air and / or humidity contamination inside the reactor containing the materials; d) simultaneous introduction of the reagents into the reactor and ignition of the plasma;

e) setting of process parameters in the reaction chamber including: choice of gas or feed mixture; supply gas flow; gas pressure; working power; water cooling of the RF electrode; bias potential of the target electrode (s).

f) Plasmochemical deposition for a time sufficient for the formation of the first organic or inorganic coating having a thickness between 5 nm and a few microns and simultaneous formation, within it, of nanometric clusters of silver or other metals or bioactive oxides by sputtering, -g) shutdown of the plasma, after a time sufficient to produce a film of the desired thickness, and evacuation of the reactive gases from the reaction chamber;

h <)> shutdown of pumping systems and air intake;

i) opening of the reactor with replacement of the silver tar-get (or tar-get (or other bioactive metals or oxides) with inert ones (for example steel) if there is no configuration that foresees the use of shutters for cover the target electrode (s);

j) repetition of the procedures described in points b) -c) -d) and e)

k) plasmochemical deposition for a time sufficient for the formation of the second organic barrier coating, possibly also characterized by other properties (unfouling, biocompatibility, etc.) with a thickness between 5 and 5000 nanometers;

l) shutdown of the plasma and evacuation of reactive gases from the reaction chamber;

m) shutdown of pumping systems and air intake;

n) extraction of biomedical devices or treated artifacts.

If you have a shutter, the procedure in point g is not necessary and after covering the target (s) with these devices, you can proceed directly to procedures from i) to m). This procedure obviously changes according to the type of technology used to obtain the "reserve" film or material.

EXAMPLE 3

According to preferred embodiments of the process, the step of treating the biomedical devices such as those shown for example of the following invention (PEO-like and Ag / PEO-like) obtained in the reactor described in Example 1 is envisaged to be carried out under the following experimental conditions:

â – ¡pressure between 1 mTorr and 50 Torr;

â – ¡power between 0.001 and 20.00 W / cm <2> (referred to the surface of the electrodes);

â – ¡flow of the gases involved in the process between 0.01 and 10,000 sccm (standard cubic centimeters per minute), â – ¡treatment time between 3s and 10 hours.

By varying the gas supplying the plasma and the deposition conditions, it is possible to obtain thin films with a continuously variable composition with the deposition conditions, with absolutely unique characteristics; using precursor type ethylene glycols it is possible to deposit organic coatings with unfouling characteristics, of resistance, that is, to adhesion and contamination with organic and biological substances in an aqueous environment By coupling a sputtering process to a conventional PE-CVD process, it is possible to produce nanocomposite coatings, consisting, that is, of nanometric clusters (metal, ceramic, oxide or polymeric) included in thin film of organic or inorganic nature.

EXAMPLE 4

The XPS analysis of the barrier nanocomposite films described above (PEO-like multilayer on Ag / PEO-like) showed the presence of a quantity of silver varying between 1 and 40% (in atomic percentage) and of a good, uniform degree and compliant, covering the nano composite films by means of the barrier film. Wettability measurements on films with and without barrier reveal a contact angle with water ranging from 20 ± 3 ° to 95 ± 5 ° depending on the quantity of silver incorporated in the organic matrix and the roughness of the deposited film. Measurements of silver release in aqueous media were carried out by ICP-MS spectrometry on samples taken from cell culture media. These measurements revealed that the release of silver gradually decreases over time passing, for example, for films containing 5% silver, from 0.15ppm * h <-1> * cm <-2> to about 0.005ppm * h <- 1> * cm <-2> after 6 days of exposure to DMEM medium [Dulbecco's Modified Eagle's Medium). The bactericidal effect was evaluated by means of the zone of inhibition test of materials coated with films containing silver, prepared under various experimental conditions and coated with various barrier films. The biological test was carried out with agar medium (Tryptic Soy Agar, TSA) containing 1x10 <8> cfu / mL of Staphylococcus epidermidis RP62A ATCC 35984 (slime producer, Gram). The test was performed after 72 h of incubation and continued for a week in order to verify any late effects. The size of the circular crown that forms around the modified material gives a measure of the antibacterial effect of the material.

Figure 3 shows the results of the zone of inhibition test carried out on films containing the least amount of incorporated silver (XPS li silver). From the results reported it is clear that materials not containing silver such as PET as it is (PET T.Q.), and PEO-like films containing 40% (PEO40%) of EO ether groups deposited on PET do not show an antibacterial effect. The histogram in Figure 3 shows that the reduction of the antibacterial effect by the barrier film depends both on the quantity of EO groups (PEO character) and on the thickness of the barrier film, reported in brackets. It can be deduced that thicker (60 nm) and / or more cross-linked (PEO20%) barrier films significantly reduce the release of Ag + ions and the antibacterial effect, almost to cancel it. This effect is confirmed by ICP-MS measurements; the silver released was quantified in DMEM (Dulbecco's Modified Eagle's Medium) cell culture medium with 3T3 fibroblast cell line at different incubation times taken during an experiment to evaluate the cytotoxicity of these materials. Release was monitored after 24, 48 and 72 hours of exposure of the films to the cell culture medium, incubated with the 3T3 fibroblast cell line. Portions of culture medium were digested with hot concentrated HNO3, dried and taken up with a 2% v / v solution of HNO3. During exposure to the aqueous medium, films containing the highest concentration of silver (PEO20% Ag5%) release more silver over time than films containing the least (Figure 2). On the other hand, to modulate the release from films containing the greatest amount of silver, more crosslinked (lower percentage of ether groups, lower PEO character) and thicker barrier films will be needed (Figure 4).

The cytotoxicity experiments carried out in conjunction with the determination of the release made it possible to verify that, in the absence of barrier film, there is inhibition of adhesion and cell proliferation of 3T3 fibroblasts (line particularly sensitive to silver) on Ag / PEO-like coatings . In the presence of barrier films, however, the 3T3 fibroblasts adhere and proliferate undisturbed at the base of the cell culture wells, around and on the treated materials. These results confirm that it is possible to reduce the cytotoxic effect of the released silver while not giving up its antibacterial effect.

Claims (16)

CLAIMS 1. Process for the realization, or the restoration, by plasmochemical way of a film (barrier film), eventually multilayer, of nanometric thickness, which allows to carry out in a controlled, uniform and lasting way the release of substances of interest from a substrate that includes as micro / nano particles the substance to be released, or from a layer deposited on the substrate which includes as micro / nano particles the substance to be released, or from a layer of substance to be released deposited on the substrate, or from a substrate which is the substance to be released possibly in the form of particles, in which the substance to be released is chosen from the group comprising metals and compounds with antibacterial properties and biologically active molecules, such as drugs, hormones, plant extracts, oligopeptides, lipids, proteins and glycides; the layer with the substance to be released (matrix) is obtained by depositing a layer, inorganic or organic, possibly with a structure similar to polyethylene oxide polymers (PEO-like); the barrier film is obtained by depositing at least one layer, inorganic or organic, possibly with a structure similar to polyethylene oxide polymers (PEO-like); and the substrates on which the deposits are made are medical-surgical devices, commonly used artifacts, structures known as scaffolds and the substances to be released themselves, it being provided that, in the event that the substance to be released is silver or other metal or bioreactive oxide, the matrix layer is obtained with the simultaneous deposit of the substance to be released and the substance that includes it. 2. Process according to claim 1, in which, on devices of medical-surgical interest or on commonly used products, a multilayer coating of organic or inorganic polymer, possibly with a structure similar to polyethylene oxide polymers (PEO- like), substantially with the following operations: - deposition of a first layer (matrix) possibly PEO-like with simultaneous deposition of silver or other metal or bioactive oxide, with antibacterial properties, by sputtering with formation of clusters of the same in the deposited substrate; deposition of a film with one or more layers possibly PEO-like (barrier layers, not fouling), the resulting coating being able to make the release of antibacterial ions deriving from silver (Ag <+>) or other metals or bioactive oxides controlled, uniform and lasting, depending on the chemical nature of the material deposited, in humid and to release quantities of silver, other metal or bioactive oxide, antibacterial but not cytotoxic. 3. Process according to claim 2, in which the deposit of the first layer (matrix) is carried out with the simultaneous deposition of silver, copper, zinc, titanium, gold, gallium, carbon or titanium oxide and their combinations. 4. Process according to any one of claims 1 to 3, in which the barrier film, possibly multilayer, is obtained with plasma exposure for a time sufficient to achieve a thickness of between 5 nanometers and 50 micrometers on each layer, in experimental conditions such as to control the chemical nature and degree of crosslinking of the film. 5. Process according to any one of claims 1 to 4, in which the barrier film, possibly multilayer, is made with a chemical composition gradient that is more cross-linked at the beginning of the process and less cross-linked at the end , or with several layers of a completely different chemical nature, multifunctional, such as antibacterial / unfouling, antibacterial / cell-adhesive, and antibacterial / hydrophobic. 6. Process according to any one of claims 1 to 5, in which the deposition of the barrier film layers in PEO-like unfouling polymer is carried out with plasma under mild deposition conditions, i.e. power between 0.001 and 20.00 W / cm <2> (referred to the surface of the electrodes), precursor flows between 0.01 and 10.00 sccm (standard cubie centimeters per minute), pressure between 1 mTorr and 50 Torr, in alternating current with frequencies of order of MHz or KHz. 7. Process according to claim 6, in which the low frequency plasma is fed at radio frequency. 8. Process according to any one of the preceding claims 1 to 7, in which the first layer (matrix) containing the substance to be released is obtained by exposure to plasma and silver sputtering for a time sufficient to achieve a layer thickness between 10 nanometers and 50 micrometers. 9. Process according to claims 1 to 8, in which the barrier film, possibly multilayer, is obtained by exposure to plasma under variable conditions of power, pressure, supply gas, for a time sufficient to achieve a layer thickness of between 5 nm and 50 micrometers with the chemical characteristics and thickness suitable to exert the barrier effect. 10. Process according to any one of claims 1 to 9, wherein the precursor, for the plasma deposition of the barrier film, comprises gases or vapors of non-oxygen-containing precursors, such as alkanes, alkenes and alkynes; gases or vapors of non-plasma polymerizable oxygen-containing compounds such as O2, CO2 and H2O alone or mixed with polymerizable precursors; volatile compounds containing oxygenated groups such as for example glycols, ethers, alcohols, carboxylic acids such as acrylic acid, aldehydes, anhydrides, ketones, phenols; gases or vapors of non-plasma polymerizable nitrogen-containing compounds such as N2, NH3 to be used alone or mixed with other plasma polymerizable precursors; plasma polymerizable volatile precursor vapors such as for example primary, secondary and tertiary amines and amides such as for example allyl amine, diaminocyclohexane, N-isopropylacrylamide; inorganic precursors such as silicone for example. 11. Medical-surgical devices, characterized in that they are coated with the multilayer film obtainable with the process of claims 1 to 10. 12. Medical-surgical devices, as per claim 11, such as syringes, prostheses, catheters, contact lenses, heart valves, intraocular lenses and filters for hemodialysis. 13. Commonly used articles, characterized in that they are coated with the multilayer film obtainable with the process of claims 1 to 10. 14. Products according to claim 13, such as filters for hemodialysis, filters for air conditioning systems, toothbrushes, blades for long-lasting razors, tubes for fluid circulation. 15. Structures known as scaffolds, characterized by being coated with a multilayer film obtainable with the process of claim 1, in the first layer of which (matrix) molecules capable of interfering with biological processes, such as drugs, hormones, are dispersed plant extracts, oligopeptides, lipids, protides and glycides, the release of said molecules being controlled and their modulated effect. 16. Biologically active substances, possibly in the form of particles, characterized in that they are coated with one or more layers of barrier film obtainable with the process of claim 1, the release of said substances being controlled and their effect modulated.