Method and device for transferring gas molecules from a gaseous medium into a liquid medium or vice versa

Abstract

The present invention relates. to methods and devices for exchanging gas molecules between a gaseous medium and a liquid medium which are particularly suited for applications such as blood oxygenation in heart-lung machines and gas scrubbing. The method of the invention comprises the following steps: a) providing a liquid medium having a surface tension in the range of from 0.02 N/m to 0.06 N/m, b) providing a gaseous medium, c) providing a membrane on an interface between the liquid medium and the gaseous medium, wherein the membrane comprises i) a carrier substrate with through-going openings having a mean diameter in the range from 0.2 ?.Math.? to 200 ??.Math., and ii) a porous superamphiphobic coating layer with openings having a mean diameter in the range from 0.1 ?m to 10 ?m, which is provided at least on the substrate surface facing the liquid medium, wherein either the liquid medium or the gaseous medium, preferably the gaseous medium, comprises at least one target gas to be transferred and said membrane is permeable for the at least one gas to be transferred and not permeable for the liquid medium due to the super-amphiphobic properties of the membrane surface facing the liquid medium with respect to said liquid medium, d) contacting the gaseous medium with the liquid medium via said superamphiphobic layer for a sufficient time to enrich the liquid or gaseous target medium with the at least one gas to be transferred.

Claims

1. A method for transferring gas molecules from a gaseous medium into a liquid medium or vice versa comprising at least the following steps: a) providing a liquid medium having a surface tension (liquid-air) in a range of from 0.02 N/m to 0.06 N/m, b) providing a gaseous medium, c) providing a membrane on an interface between the liquid medium and the gaseous medium, wherein the membrane comprises i) a carrier substrate with through-going openings having a mean diameter in a range from 0.2 ?m to 200 ?m, and ii) a porous superamphiphobic coating layer with openings having a mean diameter in a range from 0.1 ?m to 10 ?m, which coating layer comprises a surface exhibiting a contact angle of at least 150? with respect to 10 ?l sized drops of water and also a contact angle of at least 150? with respect to 10 ?l sized drops of liquids having a surface tension of not more than 0.06 N/m, which is provided at least on a substrate surface facing the liquid medium, wherein either the liquid medium or the gaseous medium, comprises at least one target gas to be transferred and said membrane is permeable for the at least one gas to be transferred and not permeable for the liquid medium due to the superamphiphobic properties of the membrane surface facing the liquid medium with respect to said liquid medium, d) contacting the gaseous medium with the liquid medium via said superamphiphobic layer for a sufficient time to enrich the liquid or gaseous target medium with the at least one gas to be transferred.

2. The method according to claim 1, wherein gas molecules are transferred from a gaseous medium into a liquid medium.

3. The method according to claim 1, wherein the at least one gas to be transferred is a member selected from the group consisting of oxygen, carbon dioxide, TiCl.sub.4, nitrogen oxides, SO.sub.2, SO.sub.3, H.sub.2S, HCl, HCN, ammonia, amines, and silanes.

4. A device for transferring gas molecules and/or particles from a gaseous medium into a liquid medium or vice versa comprising: a) a liquid medium having a surface tension (liquid-air) in a range of 0.02 N/m to 0.06 N/m, b) a gaseous medium, c) a membrane provided on an interface between the liquid medium and the gaseous medium, wherein the membrane comprises i) a carrier substrate with through-going openings having a mean diameter in a range from 0.2 ?m to 200 ?m, and ii) a porous superamphiphobic coating layer with openings having a mean diameter in a range from 0.1 ?m to 10 ?m, which coating layer comprises a surface having a contact angle of at least 150? with respect to 10 ?l sized drops of water and also a contact angle of at least 150? with respect to 10 ?l sized drops of liquids having a surface tension of not more than 0.06 N/m, which is provided at least on the substrate surface facing the liquid medium, which membrane is permeable for at least one gas contained in the liquid or gaseous medium, and not permeable for the liquid medium due to the superamphiphobic properties of the membrane surface facing the liquid medium with respect to said liquid medium.

5. The device according to claim 4 which is a gas scrubber or an oxygenator of a heart-lung machine or a component thereof.

6. The device according to claim 4, wherein the superamphiphobic coating layer comprises strings, particles embedded in fibers, columns, aggregates or an arrangement of nano- or microparticles having a mean diameter in a range of 12 nm to 2 ?m, which particles comprise a material of low surface energy or are coated with a material of low surface energy, wherein the low surface energy material has a surface tension (air-substrate surface) less than 0.03 N/m.

7. The device according to claim 4, wherein the carrier substrate comprises a mesh, fibers, a textile, a micro- or mesoporous foam or a porous 3-dimensional structure with a defined shape.

8. The device according to claim 7, wherein the porous 3-dimensional structure with a defined shape comprises an elongated longitudinally extended hollow body having at least one lumen or cavity provided in an interior thereof.

9. The device according to claim 4, wherein the membrane comprises a carrier substrate with a microporous or mesoporous superamphiphobic layer provided on at least one substrate surface and wherein said porous layer is partially filled with the gaseous medium.

10. The device according to claim 4, wherein the liquid medium exerts a hydrostatic pressure of at least 100 Pa, onto the superamphiphobic layer of the membrane.

11. The method according to claim 1, wherein the liquid medium comprises blood, the gaseous medium is oxygen or an oxygen-containing gas mixture and the at least one gas to be transferred from the gaseous medium is oxygen.

12. The device according to claim 4, wherein the membrane is produced by providing a carrier substrate with through-going openings having a mean diameter in a range from 0.2 ?m to 200 ?m, depositing particles having a mean diameter in a range of from 12 nm to 2 ?m on the substrate surface, and, optionally, coating the particles with a hydrophobic top coating.

13. The device according to claim 12, wherein the particles are polymer particles, silica particles or particles coated with a shell selected from the group consisting of a silica shell, a metal oxide shell, a Ti{OCH(CH.sub.3).sub.2}.sub.4 shell, and a hybrid shell comprising 2 or more materials, wherein the silica particles or particles coated with a shell are further coated with a hydrophobic top coating.

14. The method according to claim 1, wherein the method is used for gas scrubbing, flue gas desulfurization, silane capturing, or for medical treatment.

15. The method according to claim 1, wherein the superamphiphobic coating layer comprises strings, particles embedded in fibers, columns, aggregates or an arrangement of nano- or microparticles having a mean diameter in a range of 12 nm to 2 ?m, which particles comprise a material of low surface energy or are coated with a material of low surface energy, wherein the low surface energy material has a surface tension (air-substrate surface) less than 0.03 N/m.

16. The method according to claim 1, wherein the carrier substrate comprises a mesh, fibers, a textile, a micro- or mesoporous foam or a porous 3-dimensional structure with a defined shape.

17. The method according to claim 1, wherein the membrane comprises a carrier substrate with a microporous or mesoporous superamphiphobic layer provided on at least one substrate surface and wherein said porous layer is partially filled with the gaseous medium.

18. The method according to claim 1, wherein the liquid medium exerts a hydrostatic pressure of at least 100 Pa, onto the superamphiphobic layer of the membrane.

19. The method according to claim 1, wherein the membrane is produced by providing a carrier substrate with through-going openings having a mean diameter in a range from 0.2 ?m to 200 ?m, depositing particles having a mean diameter in a range of from 12 nm to 2 ?m on the substrate surface, and, optionally, coating the particles with a hydrophobic top coating.

20. The method according to claim 19, wherein the particles are polymer particles, silica particles or particles coated with a shell selected from the group consisting of a silica shell, a metal oxide shell, a Ti{OCH(CH.sub.3).sub.2}.sub.4 shell, and a hybrid shell comprising 2 or more materials, wherein the silica particles or particles coated with a shell are further coated with a hydrophobic top coating.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the neutralization of a NaOH solution containing the indicator phenolphthalein with CO.sub.2 diffused through a superamphiphobic membrane (indicated by the disappearance of the characteristic absorption of phenolphthalein)

(2) 1A: gas transfer through a capillary (length 3 cm, diameter 3 mm) formed from a metal mesh-based membrane: UV-VIS spectrum as a function of wavelength

(3) 1B: gas transfer through a flow cell with 2 flat membranes based on a metal mesh (mesh width 0.032 mm): UV-VIS spectrum as a function of time at the constant wavelength of 555 nm (absorption maximum of phenolphthalein)

(4) FIG. 2 UV-VIS spectra of oxygenated and deoxygenated blood (1.2%) in PBS

(5) 2A: Oxygenation by oxygen diffusion through a superamphiphobic membrane recorded in a flow cell.

(6) 2B: control

(7) FIG. 3 Experimental setups

(8) 3A: Scheme of the principal setup for effecting and monitoring gas transfer through a superamphiphobic membrane including pump, cuvette, gas chamber, capillary/flow cell

(9) Not shown: gas reservoir.

(10) 3B: Scheme of a flow cell with two mountable superamphiphobic membranes

(11) 3C: Photographs of superamphiphobic capillaries using a metal mesh as carrier substrate

(12) FIG. 4 shows the relative adsorption of blood proteins and blood cells to different surfaces including a superamphiphobic surface.

(13) 4A: quantitative protein adsorption (Pierce test)

(14) 4B: SEM micrographs showing adsorption of blood to an uncoated metal mesh (left) versus a superamphiphobic mesh (right)

(15) FIG. 5 shows TEM micrographs of particles constituting the superamphiphobic layer of the membrane used in the invention

(16) 5A: Fractal network formed by soot particles imaged by scanning electron microscopy (SEM)

(17) 5B: String of soot particles (SEM image)

(18) 5C: Soot particles after coating with a silica shell (SEM image)

(19) 5D: High magnification image of soot particles after coating with a silica shell (SEM image)

(20) 5E: Transmission electron microscope image of coating after calcination showing the silica shell

(21) FIG. 6 shows strings and fibers comprising particles with a silica shell and PVA (SEM micrographs)

(22) 6A: Strings composed of PVA and silica particles of 1000 nm diameter

(23) 6B: Fiber composed of PVA and silica particles of 200 nm diameter

(24) The following non-limiting examples are provided to illustrate the present invention in more detail, however, without limiting the same to the specific features and parameters thereof.

Example 1

Preparation of a Superamphiphobic Layer on a Mesh

(25) The surface to be coated, in this case a metal mesh, was held above a flame of a paraffin candle. Deposition of a soot layer immediately turned the metal black. Scanning electron microscopy revealed that the soot consists of carbon particles with a typical diameter of 30-40 nm, forming a loose, fractal-like network (FIG. 5B). A water drop gently deposited on the surface shows a contact angle above 160? and rolls off easily, proving the surface's superhydrophobicity. However, the structure is fragile as the particle-particle interactions are only physical and weak. When water rolls off the surface, the drop carries soot particles with it until almost all of the soot deposit is removed and the drop undergoes a wetting transition. Therefore, in order to stabilize this structure the soot layer is coated with a silica shell making use of chemical vapour deposition (CVD) of tetraethoxysilane (TES) catalyzed by ammonia. The soot-coated substrates were placed in a desiccator together with two open glass vessels containing tetraethoxysilane (TES) and ammonia, respectively. Similar to a St?ber reaction, silica is formed by hydrolysis and condensation of TES. The shell thickness can be tuned by the duration of CVD. After 24 h the particles are coated by a 20?5 nm thick silica shell (FIG. 5C, D). Calcinating the hybrid carbon/silica network at 600? C. for 2 h in air causes combustion of the carbon core (FIG. 5E) and a decrease in the shell thickness, while the layer keeps its roughness and network texture. Only isolated chains of particles, which are not linked in the network, broke during calcination. To reduce the surface energy the hydrophilic silica shells were coated by a semi-fluorinated silane by chemical vapor deposition. After fluorination a water drop placed on top of the coating formed a static contact angle of 165??1?, with a roll-off angle lower than 1?. Owing to the extremely low adhesion of the coating, with water it was difficult to deposit water drop, because they immediately tended to roll off. When drops of organic liquid were deposited, the static contact angles ranged from 154? for tetradecane up to 162? for diiodomethane.

(26) FIG. 6 shows strings and fibers comprising particles with a silica shell and PVA (SEM micrographs) obtained by mixing an aqueous dispersion of PVA and silica colloids.

(27) Stirring of 10 wt % PVA for 3 h at 85? C. and subsequently adding 56 wt % silica particles (1000 nm) resulted in a network comprising necklace-like strings (shown in FIG. 6A). The final concentrations of silica, PVA and water were 8 wt %, 8 wt % and 84 wt %, respectively.

(28) Stirring of 10 wt % PVA for 3 h at 85? C. and subsequently adding 32 wt % silica particles (200 nm) resulted in a fiber structure (shown in FIG. 6B). The final concentrations of silica, PVA and water were 8 wt %, 8 wt % and 84 wt %, respectively.

(29) These strings and fibers can be immobilized on a desired carrier substrate surface by contacting the above or similar mixtures with the carrier substrate using any suitable method of the art, e.g. by means of electrospinning.

Example 2

Oxygenation of Blood Via a Superamphiphobic Membrane

(30) The controlled oxygenation of deoxygenated blood by oxygen diffusion through a superamphiphobic membrane in a closed pumped system was shown to be possible using a flow cell with two superamphiphobic membranes as side walls (FIG. 3B). Depending on the specific application superamphiphobic meshes of different sizes can be prepared separately and then be fixed in the flow cell. It is also possible to place two meshes right behind another if desired.

(31) The cell was placed into an air tight gas box. This gas box was equipped with two valves for in-flowing and out-flowing gas, connection tubes for in-flowing and out-flowing liquid and an oxygen partial pressure sensor.

(32) For these experiments, stainless steel meshes with a mesh-width of 32 micrometer and a wire diameter of 28 micrometer were used. The surfaces were made superamphiphobic using the procedure described in Example 1. The inner compartment of the flow cell has an elliptical flow profile with a transverse diameter of 2 cm, a conjugate diameter of 1 cm and a depth of 2 mm between the two superamphiphobic mesh-walls, resulting in an entire volume of 3.1 cm.sup.2. The inner diameter of the cell influx and out-flux tube is 1.37 mm. The flow cell was connected to a tubing pump (flow=4 ml/min), a reservoir and a UV-VIS flow cuvette using Tygon? tubing (inner diameter=1.42 mm). FIG. 3A shows the principal experimental setup including pump, cuvette, gas chamber, capillary/flow cell (note that a capillary of a desired alternate shape, e.g. such as described in Example 3, could also be used instead of the flow cell as described above).

(33) The gas box was flushed with a constant N.sub.2 stream for 2 hours, until no more oxygen could be detected by the oxygen partial pressure sensor. Deoxygenated 1.2% blood/PBS solution (see above) was transferred to the reservoir under inert gas conditions. The total volume of the entire system was approx. 19 ml. Spectra were measured subsequently; the measurement of one spectrum took approximately 1 min 17 sec.

(34) The gas box was flushed for further 16 min with N.sub.2 and then subsequently flushed with 5 balloons (V=3-4 liter) of oxygen over a period of 29 min. The spectrums for t=0 min and t=45 min are shown in FIG. 2a. Comparison of FIG. 2a with FIG. 2B (control) demonstrates that pumped blood/PBS was successfully oxygenated. The solution was pumped for more than 1 hour in a closed system without any leakage.

(35) The timescale of oxygenation depends on various points: Size of gas box (V=?2 liter) Flushing speed/time needed for replacement of N.sub.2 by O.sub.2 atmosphere Total Area of interfacial membrane (A=3.1 cm.sup.2) Mesh width Flow speed of the liquid

(36) Direct oxygenation of blood was conducted and measured in a control experiment as follows:

(37) UV-VIS-spectra of oxygenated and deoxygenated blood were measured in a sealed cuevette (d=2 mm) (FIG. 2B).

(38) 1.2% blood in PBS solution was oxygenated under ambient conditions. For this, the 20 ml Hellma cuvette was kept open for 20 min and the blood was slightly stirred. The oxygenized blood was directly measured. In order to deoxygenize the blood/PBS solution, the solution was heated to 37? C. and a continuous stream of N.sub.2 was bubbled through the liquid over 30 min. The blood/PBS solution was then transferred to a sealable cuevette under inert-gas conditions and the sample was measured as well. Spectra are baseline corrected to 800 nm (isosbestic point of hemoglobin).

Example 3

Gas Diffusion Through a Superamphiphobic Membrane

(39) Experimental Setup:

(40) The same principal setup as described in Example 2 for the oxygenation of blood/PBS solutions was used. Again, it consisted of a pump, Tygon?-tubing, a flow cuvette, a reservoir and an air-tight gas box containing a superamphiphobic capillary/flow cell. The gas box was equipped with two valves for in-flowing and out-flowing gas, connection tubes for in-flowing and out-flowing liquid and an oxygen partial pressure sensor. In this case, sodium hydroxide solution with phenolphthalein was pumped through the capillary or flow cell. The capillary and the flow cell both partly consist of a superamphiphobic mesh, which was coated as described in Example 1 by deposition of paraffin candle soot, CVD of tetraethoxysilane and hydrophobization with trichlorofluorosilane. These meshes act as membranes and form a barrier to the outer gas atmosphere. The gas box was either filled with N.sub.2 or CO.sub.2.

(41) The flow cell used was similar to or identical with the flow cell in Example 2. For the gas diffusion experiments described herein, superamphiphobic capillaries (FIG. 3C) were also used. The manufacturing of these capillaries was slightly different from the manufacturing of plane superamphiphobic surfaces. A mesh piece with the size of about 3 cm to 6 cm?1 cm is covered for ?45 s with candle soot from one side. Afterwards the soot template is stabilized by chemical vapor deposition of tetraethoxysilane for 24 h in a desiccator (in analogy to the usual procedure). The samples were calcinated at 600? C. for 2 hours. After calcination the meshes were shaped into capillaries by hand. The inner part of the tube was coated with the fractal silica network; the outer part of the tube had no coating. The capillaries had an inner diameter of ?2.5 mm to 3 mm and a length of 3 cm to 6 cm. These capillaries were permanently fixed by wrapping a copper wire (d=0.01 mm) around them. The average distance between neighboring copper strings was 1 mm to 2 mm. These capillaries were hydrophobized. For this, 300 microliter semifluorinated trichlorosilane was put in an open glass vessel and placed in a desiccator for 2 hours at ?200 mbar (in analogy to the standard procedure described in Example 1). In order to connect the superamphiphobic capillaries with the pump system stainless steel metal tubes with a length of 1.3 cm and an inner diameter of 2 mm were fixed at the opening of the superamphiphobic capillaries with the help of heat-shrink tubes. To make a tight connection between the capillary and the metal tube, one shrinking tube of length=1 cm and an inner diameter=0.6 cm was placed first from each side and heated. An equal piece was put over the one beforehand with an offset of ?0.5 cm, so that one half of the prior shrinking tube was covered and one half of the superamphiphobic capillary was covered (see capillary at top, FIG. 3C). In some cases, a third piece of shrinking tube with length=?0.5 cm and an inner diameter=0.3 cm was placed over the connection part between metal tube and first shrinking tube and was heated (see capillary at bottom, FIG. 3C). Shrinking tubes were heated using a fire-lighter.

(42) To prove that gas can diffuse through these superamphiphobic meshes, the acid-base neutralization of sodium hydroxide with carbonic acid was used as a model system. Therefore, in a first step a sodium hydroxide solution with phenolphthalein as indicator was prepared. Phenolphthalein is pink in the presence of base and turns colorless in the neutral and acidic regime (pK.sub.s=9.7). The tubing system and the gas box containing the superamphiphobic capillary or flow cell were flushed 7 times with 3-4 liter N.sub.2. The basic phenolphthalein solution (pink) was transferred to the reservoir (total volume of approx. 19-22 ml). After a predetermined time (about 25 min) the gas box was flushed with CO.sub.2. If the superamphiphobic meshes are permeable to gas, CO.sub.2 will have contact to the pumped solution after a certain diffusion time. The pumped solution mainly consists of water and in the presence of water CO.sub.2 is in equilibrium with carbonic acid (Equation 1). The carbonic acid will be neutralized by the dissolved sodium hydroxide. Once all sodium hydroxide is neutralized, phenolphthalein will turn colorless and the solution loses its characteristic UV-VIS absorption bands.
CO.sub.2+H.sub.2OH.sub.2CO.sub.3(aq)
H.sub.2CO.sub.3(aq)+2NaOHNa.sub.2CO.sub.3+2H.sub.2OEquation 1:

(43) 1. The first example was carried out using a superamphiphobic capillary (length=3 cm, inner diameter=3 mm) and a flow velocity of 7.6 ml/min. The concentration of the sodium hydroxide solution was pH=10.3. UV-VIS spectra were constantly recorded as a function of wavelength (700-350 nm) every 1 min 20 sec (FIG. 1A). Up to 12 min the spectra were constant (only one spectrum shown for clarity). After ?12 min the gas box was flushed with 3-4 liter CO.sub.2 (1 balloon) to replace the N.sub.2-atmosphere with a CO.sub.2-atmosphere. FIG. 1A shows two subsequently recorded spectra: One directly before flushing and the other directly after flushing the gas box with CO.sub.2. This diagram demonstrates that the sodium hydroxide solution (pH=10.3) was immediately neutralized and that the main absorption peak of phenolphthalein is no longer detectable.

(44) 2. The second experiment shows the same principal procedure recorded as a function of time at a constant wavelength (absorption maximum of phenolphthalein at 555 nm) (FIG. 1B). In contrast to the first experiment, the flow cell described in Example 2 was used for this experiment. A sodium hydroxide solution with pH=11.4 was provided and its flow velocity was 7 ml/min. After ?24 min the gas box was flushed with 3-4 liter CO.sub.2 (1 balloon) to replace the N.sub.2-atmosphere with a CO.sub.2-atmosphere.

(45) FIG. 1B shows a significant drop in absorbance after replacing the N.sub.2 gas atmosphere of the gas box with 3-4 liter CO.sub.2. The absorbance value drops to almost zero what corresponds to a total neutralization of sodium hydroxide in solution due to CO.sub.2 diffusion through the superamphiphobic mesh. No liquid leakage could be observed. The timescale of gas-diffusion and neutralization of the actual sodium hydroxide solution passing through the flow cell took roughly about 1 min 12 sec and depends on various points: Concentration of sodium hydroxide solution Total Area of interfacial membrane. A=3.1 cm.sup.2 for flow cell, A=28 cm.sup.2 for capillary Flow speed and flow profile in tube and cuvette Flushing speed/time needed for replacement of N.sub.2 by CO.sub.2 atmosphere Size of gas chamber (V=?2 liter)

(46) The above experiments demonstrate that gas molecules from the surrounding atmosphere can freely diffuse through these superamphiphobic meshes. The meshes used in said experiments have comparatively big mesh openings (32 micrometers) and the fractal superamphiphobic coating is porous, with pores in the nanometer to micrometer scale. Gas molecules are only a few A in size and, therefore, are able to penetrate the structure easily. Liquid passing through the superamphiphobic capillary or flow cell is repelled and does not penetrate the mesh due to the liquid's surface tension. This allows a continuous pumping of the liquid at a constant flow rate without leakage for several hours.

Example 3

Protein and Cell Adhesion on Superamphiphobic Surfaces

(47) 1. Protein Adhesion

(48) Superamphiphobic surfaces prepared as outlined below were brought into contact with human whole blood. After a predetermined time (typically a few hours), the whole blood was removed and the protein adhesion on the surfaces was quantified by the known Pierce Test.

(49) Stainless steel meshes were used for each experiment. The mesh width was 32 micrometers and the steel wires had a diameter of 28 micrometers. Five mesh pieces of 1.5 cm?2.5 cm were cut, rinsed with water, ethanol and water, respectively. One mesh piece was used without any further modification as control.

(50) The other mesh pieces were attached to a steel mounting using a copper wire as shown in FIG. 4C. These suspended mesh pieces were coated with paraffin candle soot from both sides in analogy to the procedure described in Example 1. All steps (CVD of tetraethoxysilane, calcination at 600? C., hydrophobization by CVD of trichlorofluorosilane) were carried out with suspended samples to prevent any possible damage of the coating due to contact with the surrounding environment. Some samples showed manufacturing defects and proved to be hydrophobic but not oleophobic. One of these superhydrophobic but not super-olephobic surfaces was examined as well as a comparative sample (hydrophob, oleophil). For comparison an untreated metal mesh was also investigated (control).

(51) The samples were immerged into whole human blood for 3 days at 21? C. (FIG. 4c). After 3 days the samples were taken out and the upper part, which was not immersed, was cut off.

(52) The resulting meshes (approx. 1.5?1.5 cm) were cut into smaller pieces, weight and transferred to an Eppendorf cup for further protein quantification using the Pierce Test. In principle, the Pierce 660 nm Protein Assay (from Pierce Biotechnology, Rockford, Ill., USA) is a colorimetric method to determine the total protein amount based on absorbance.

(53) The results of the Pierce Test are shown in FIG. 4A. Results are given in total amount of protein for each sample in microgram (?g) and, since the size of the samples varied slightly, in mass of proteins per milligram (mg) of weight mesh. The values for coated and uncoated meshes can be compared since coated and uncoated meshes are about equal in mass. A significantly reduced protein adhesion could be observed for all three super-amphiphobic meshes (below 0.01 mg protein per mg mesh). The untreated metal mesh showed about 0.04 mg protein per mg mesh and the hydrophob but oleophilic meshes showed about 0.07 mg protein per mg mesh.

(54) 2. Cell Adhesion

(55) Superamphiphobic meshes with a size of approx. 1 cm?1 cm were prepared as described above. The samples were introduced into a small sealable chamber with a water reservoir to provide air humidity. Blood drops were put onto the superamphiphobic meshes and the chamber was sealed with parafilm tape. The drops rested statically for 30 min, 4 h 24 min h and 48 h on the meshes and were carefully removed without damaging the surface after the specified times. For comparison, a drop was placed on an uncoated metal mesh. Samples were investigated using scanning electron microscopy.

(56) Scanning electron microscopy revealed that the untreated metal mesh was coated with a mixture of cells (6 to 8 micrometers) and an organic residue (FIG. 4B, left). For size comparison, the structure of a superamphiphobic mesh is shown on the right hand side with the same resolution. Even after 48 h incubation time no organic residues could be found on the place where the drop was put using scanning electron microscopy.