Molecular assemblies, use of molecular assemblies for providing an anti-adhesion surface, and methods of applying molecular assemblies to solid surfaces

Abstract

A molecular assembly is disclosed for use in providing an anti-adhesion surface, and a method for applying the molecular assembly to a solid surface. The invention relates to a molecular assembly (1) having a structure formed of amphiphilic molecules (2), characterized in that the amphiphilic molecules (2) are selected from the group containing amphiphilic molecules (2), which: a) have a hydrophobic portion having a molecular weight greater than the hydrophilic portion; b) are soluble in a polar aprotic solvent and form a self-organized layer structure from solution in the absence of a polar aprotic solvent; and c) are molecularly oriented in the formed layer structure (3), particularly at the interface layer, preferably in an aqueous environment, wherein the amphiphilic molecules (2) in the formed layer structure (3) are in contact with the aqueous environment. The invention also relates to a method of coating a solid surface (5) with a molecular assembly (1), wherein the amphiphilic molecules (2) are dissolved in a polar aprotic solvent and the resulting solution is applied to the solid surface (5) by spin coating.

Description

[0001] This invention relates to a molecular assembly having a structure of amphiphilic molecules, and to the use of the molecular assembly for providing an anti-adhesion surface coating. The invention also relates to a method of coating a solid surface with the molecular assembly.

[0002] Various mechanisms influencing surface adhesion are known from the plant and animal kingdoms. These mechanisms include, for example, the lotus effect, which has been successfully transferred to technological applications. Although the molecular and structural properties defining interfacial phenomena in nature have been extensively studied, the physical mechanisms controlling adhesion remain incompletely explained to date. Current research topics include, for example, springtails (… Collembola The anti-adhesion epidermis of springtails possesses a honeycomb structure with a drooping cross-sectional profile. The lipid-rich capsule of the springtail epidermis was found to contain aliphatic hydrocarbons, particularly steroids, fatty acids, and wax esters. While it can be hypothesized that wax esters promote the anti-wetting properties of the epidermis, the role of components such as steroids and fatty acids cannot be explained. However, it is speculated that the physical properties of different molecules, in particular, are the cause of the adhesion and anti-adhesion effects.

[0003] The purpose of this invention is to provide a possible method based on physicochemical processes that utilizes the anti-adhesion properties of amphiphilic molecules.

[0004] The essence of this invention lies in the molecular assembly of selected amphiphilic molecules that are layered and undergo a spontaneous reorientation process, thus forming an adhesive entropy barrier when in contact with an aqueous environment.

[0005] A molecular assembly with amphiphilic molecular structure is proposed, characterized in that these amphiphilic molecules are selected from the group containing amphiphilic molecules. a) It has a hydrophobic portion, the molecular weight of which is larger than that of the hydrophilic portion. b) Soluble in polar aprotic solvents, and capable of forming self-organized layered structures from solution in the absence of polar aprotic solvents, and c) Based on the polarity of the environment (preferably an aqueous environment), molecular orientation is performed in the formed layered structure, especially in the interface layer. The amphiphilic molecules in the resulting structure come into contact with the aqueous environment.

[0006] The interface layer should be understood as the layer of a molecular assembly's layered structure that comes into contact with an aqueous environment. The surface of the interface layer forms the interface.

[0007] Within the meaning of this invention, contact with an aqueous environment means that one side of the structure formed by the molecular assembly according to the invention is completely wetted by water. The wetted side forms an interface.

[0008] For the molecular assembly according to the invention, consider an amphiphilic molecule having the characteristics according to a), b) and c).

[0009] The molecular assemblies according to the invention are based on the ability of selected amphiphilic molecules to form layered structures through self-organization. Therefore, the molecular assemblies are preferably layered structures of amphiphilic molecules, wherein the amphiphilic molecules are oriented perpendicular to the interface. This layered structure, consisting of one or more layers, can also be referred to as an assembly.

[0010] It has been found that the formation of molecular assemblies of selected amphiphilic molecules in molecular layer or molecular interface layer structures causes a spontaneous reorientation process induced by the amphiphilicity of the amphiphilic molecules in the molecular interface layer of the corresponding interface layer structure when in contact with an aqueous environment. This results in an anti-adhesion effect against proteins and microorganisms, especially bacteria, present in the aqueous environment.

[0011] The spontaneous reorientation process of individual molecules that induces the anti-adhesion properties of molecular assemblies is based on the tendency of individual amphiphilic molecules to spontaneously orient themselves.

[0012] The selection of amphiphilic molecules can preferably include those in which the hydrophobic portion accounts for at least 95%, preferably more than 95%, of the molecular weight of the amphiphilic molecule. This is particularly applicable to cholesterol molecules.

[0013] The desired effect of spontaneous reorientation within the molecular assembly was also found in the types of amphiphilic molecules discussed, with molecular weights in the range of 300 g / mol to 2000 g / mol, preferably in the range of 300 g / mol to 413 g / mol. Preferably, the molecular assembly according to the invention can have amphiphilic molecules with molecular weights in the range of 300 g / mol to 413 g / mol. Molecular assemblies having molecular weights greater than 2000 g / mol of the types of amphiphilic molecules discussed are conceivable. Therefore, in particular, the synthesized amphiphilic molecules can have high molecular weights, i.e., greater than 2000 g / mol, and satisfy requirements a), b), and c).

[0014] The molecular assembly according to the invention may also have amphiphilic molecules whose molecular orientation within the interface layer of the layered structure is based on the polarity of the environment, such that changes in the environmental polarity cause changes in the molecular orientation of the interface layer of the layered structure.

[0015] According to one embodiment of the molecular assembly of the present invention, the amphiphilic molecule may be a polycyclic alcohol, particularly a sterol.

[0016] It can also be specified that the molecular assembly has a mass percentage of at least 1 wt% (hereinafter abbreviated as wt%), preferably at least 10 wt% of cholesterol molecules and / or dehydrocholesterol molecules. That is, at least 1 wt%, preferably at least 10 wt%, of the selected amphiphilic molecules can be cholesterol molecules and / or dehydrocholesterol molecules. The ratio of cholesterol molecules and / or dehydrocholesterol molecules has a positive impact on the anti-adhesion effect of the molecular assembly in the form of an interfacial layer structure when in contact with an aqueous environment.

[0017] In another embodiment of the molecular assembly according to the invention, the amphiphilic molecule may be specified as stigmasterol, cholecalciferol, and / or retinol. It has been found that stigmasterol, cholecalciferol, and retinol molecules in the molecular assembly reorient relatively quickly upon contact with an aqueous environment with almost no spontaneous reorientation process, which is associated with a deterioration in the anti-adhesion properties of the molecular assembly. However, the anti-adhesion effect is significantly better than that of similar molecular assemblies with non-amphiphilic molecules. If stigmasterol, cholecalciferol, and retinol molecules are used, it is therefore advantageous to additionally use at least 1 wt%, preferably at least 10 wt%, of cholesterol molecules and / or dehydrocholesterol molecules to provide the molecular assembly.

[0018] Furthermore, cholesterol molecules, dehydrocholesterol molecules, stigmasterol molecules, cholecalciferol molecules, and retinol molecules can be used as amphiphilic molecules to form molecular assemblies. Different ratios of cholesterol molecules, dehydrocholesterol molecules, stigmasterol molecules, cholecalciferol molecules, and retinol molecules can be used.

[0019] Suppose that cholesterol molecules form triclinic crystals, resulting in a relatively "loose" arrangement within the corresponding layers of the molecular assembly. This facilitates the mobility of molecules within the layers. In contrast, stearic acid and palmitic acid molecules, components of springtail epidermis, form monoclinic crystals and accumulate in tightly packed layers, resulting in the inhibition of possible amphiphilic-induced spontaneous molecular reorientation processes when the polarity of the surrounding medium changes.

[0020] The molecular assembly according to the present invention has the following additional properties: Changes in the polarity of the surrounding / contacting medium lead to amphiphilic-induced reorientation of amphiphilic molecules in the molecular interface layer of the corresponding assemblies (layer structures). This reorientation can be detected macroscopically by dynamic contact angle measurements or microscopically by force spectroscopy based on atomic force microscopy. Upon contact with aqueous solutions, the spontaneous reorientation process of amphiphilic molecules in the molecular interface layer of the corresponding assemblies forms the basis of entropy-induced anti-adhesion properties, which can be detected by spatially and temporally resolved force spectroscopy based on atomic force microscopy.

[0021] The molecular assemblies according to the invention can be structurally designed in the form of multilayered cholesterol molecules. Such multilayered cholesterol molecules exhibit very unique behavior during dynamic contact angle measurements. In dynamic contact angle measurements, a water droplet is applied to the molecular assembly under test and the shape of the droplet is observed. The droplet is then re-adsorbed, and its shape is observed again during this process. This procedure is repeated with different application times. For molecular assemblies in a multilayered cholesterol structure, the shape of the droplet at application indicates a moderately hydrophobic interface. If the droplet is re-adsorbed immediately after application and its shape remains unchanged, it again indicates the hydrophobic properties of the molecular assembly interface. For example, at longer application times of 20 seconds, a different picture emerges. The droplet collapses, indicating that the interface of the molecular assembly is highly hydrophilic. Similar behavior has been observed for molecular assemblies of cholesterol analogs.

[0022] Therefore, the molecular assembly according to the invention can be a mixture of amphiphilic molecules, particularly cholesterol analogs having properties a), b), and c), in different proportions. Preferably, the molecular assembly according to the invention has at least 1 wt% cholesterol molecules. The molecular assembly according to the invention can also have non-amphiphilic molecules suitable for integration into the structure of the molecular assembly. The proportion of non-amphiphilic molecules in the molecular assembly can be up to 99 wt% by mass. The non-amphiphilic molecules used can be, for example, stearyl palmitate molecules. In one embodiment of the molecular assembly according to the invention, stearyl palmitate molecules can be present in a proportion of 99 wt%. In this case, cholesterol molecules are preferably used as amphiphilic molecules.

[0023] The layer structure of the molecular assembly according to the present invention can have a thickness of 15 nm.

[0024] Preferably, the molecular assembly is spin-coated onto a solid surface in the form of a layered structure of cholesterol molecules arranged perpendicular to the interface. During this process, the interface of the layered structure facing away from the solid surface comes into contact with an aqueous solution, preferably pure water.

[0025] The molecular assemblies according to the invention are particularly useful as anti-sticking agents for solid surfaces.

[0026] The subject of this invention is also a method for coating a solid surface with a molecular assembly according to the invention, wherein amphiphilic molecules are first dissolved in a polar aprotic solvent and the resulting solution is then applied to the solid surface by spin coating. The amphiphilic molecules are applied to the solid surface by spin coating. Due to the application and subsequent removal of the polar aprotic solvent, the amphiphilic molecular assembly forms a layer structure, which, after the removal of the polar aprotic solvent, can be exposed to an aqueous environment to form anti-adhesion properties.

[0027] Chloroform can be used as a polar aprotic solvent. Upon application to a solid surface, the solvent evaporates. An air stream or vacuum can be used to assist in the evaporation of the solvent.

[0028] Other solvents that can be considered are acetone, benzene, ethanol, ether, hexane, or methanol.

[0029] Further details, features, and advantages of embodiments of the present invention can be found in the following description of exemplary embodiments with reference to the accompanying drawings. In the drawings: Figure 1 A highly simplified schematic diagram of the molecular assembly according to the present invention is shown to explain the anti-adhesion properties of the molecular assembly. Figure 2 The results show measurements of bacterial adhesion (a and b) and protein adsorption (c and d) to molecular assemblies, as well as... Figure 3 The results show measurements of bacterial adhesion (a and b) and protein adsorption (c, d and e) to molecular assemblies formed by stearyl palmitate or cholesterol molecules, or molecular assemblies formed by stearyl palmitate and cholesterol molecules in different mixing ratios.

[0030] This invention is based on the discovery that the combination of selected amphiphilic molecules, particularly cholesterol molecules, and the effective self-organization of selected molecules in molecular assemblies in a multilayered structure (which produces slow, adaptive, cooperative interfacial migration of the molecular assemblies) lead to significant entropy repulsion in proteins and microorganisms.

[0031] Figure 1 a shows a highly simplified schematic diagram of a molecular assembly 1 according to the invention, using cholesterol molecule 2 as an example of the selected amphiphilic molecule. Figure 1 Figure a shows a layered structure 3 of a molecular assembly 1, which is applied to a solid surface 5, wherein cholesterol molecules 2 are oriented perpendicular to interface 4. Reference numeral 2.1 indicates a single cholesterol molecule of the molecular assembly 1 in an enlarged view. The cholesterol molecule 2.1 has a polar portion 6 and a nonpolar portion 7. The cholesterol molecules 2, arranged at interface 4 within the layered structure 3 of the molecular assembly 1 and thus located in the interfacial layer of the layered structure 3, are oriented according to the polarity of the surrounding medium. In a nonpolar environment, such as air, the nonpolar portion 7 points towards interface 4, while in a polar surrounding medium, such as water, the polar portion 6 initially oriented towards interface 4. Within the layered structure 3 of the molecular assembly 1, the cholesterol molecules 2 tend to undergo a spontaneous reorientation process upon contact with an aqueous solution, such as… Figure 1 As shown in b.

[0032] Figure 1Figure b shows molecular assembly 1, where interface 4 is in contact with a polar environment. Cholesterol molecules 2 initially oriented with their polar portions 6 toward interface 4. However, a spontaneous reorientation process is observed in individual cholesterol molecules 2 or small sets 8 of cholesterol molecules 2 (i.e., the nonpolar portions 7 temporarily pointing toward interface 4). Figure 1 In section b, taking two molecules / molecule sets as examples, these spontaneous reorientation processes are illustrated with dashed lines. The possible directions of reorientation of cholesterol molecule 2 within layer structure 3 are indicated by arrows in each case.

[0033] also, Figure 1 Figure b illustrates the transition of cholesterol molecule 2 at interface 4 from its unoriented, unbound state to a restricted protein-bound state. The binding of protein 9 at interface 4 restricts the spontaneous reorientation process of cholesterol molecule 2. This restriction is indicated by reference numeral 10. Due to the tendency of entropy-induced molecules to resume their reorientation, the binding of protein 9 at interface 4 is weakened by the minimization of free enthalpy, and thus protein 9 becomes dissociated.

[0034] The method of coating solid surface 5 with molecular assembly 1 is explained in more detail below.

[0035] Molecular assemblies 1 can be applied to solid surfaces 5 by spin coating, wherein layer structures 3 of molecular assemblies 1 are formed. Such layer structures 3 of the selected amphiphilic molecules are referred to below as SCL (spin-coated lipid multilayers).

[0036] SCLs are manufactured on silicon wafers that serve as substrates. The substrate (which can be 10 × 15 mm in size) is used for this purpose. 2 The substrate was cleaned by immersion in a solution of deionized water, ammonia, and hydrogen peroxide (volume ratio 5 / 1 / 1) at 70°C for 15 min, followed by repeated rinsing in Milli-Q water and drying in a nitrogen stream. The cleaned substrate was immediately used to produce SCLs via spin coating. For spin coating, cholesterol molecules 2 were dissolved in chloroform (2 wt%). The resulting solution was applied to the solid surface 5 via spin coating (LabSpin6, SÜSS MicroTec) at a rotation speed of 3000 rpm and an acceleration of 3000 rpm / s for 30 seconds. Once the formed layer structure 3 came into contact with the aqueous solution, anti-adhesion properties were established.

[0037] Figure 2 The results show measurements of bacterial adhesion (a and b) and protein adsorption (c and d) to molecular assemblies composed of molecules found in the lipid-rich capsule of springtails. Two different bacterial species (Staphylococcus epidermidis, Staphylococcus aureus, and Staphylococcus faecium) were used. Staphylococcus epidermidis [a] and Escherichia coli ( Escherichia coliExperiments were conducted using two different protein species (bovine serum albumin [c] and lysozyme [d]). Images a and b plot the normalized counts of bacteria found on their respective surfaces after a one-hour incubation period (normalized relative to the control surface – silica [SiO2]). Images c and d plot the absolute adsorbed protein mass on their respective surfaces (determined by measurement using an oscillating quartz microbalance). In measurements of bacterial adhesion (a and b) and protein adsorption (c and d), the minimum amount of bacteria and protein was always detected on molecular assemblies formed from cholesterol molecules. The observed differences were statistically significant.

[0038] Figure 3 The results show measurements of bacterial adhesion (a and b) and protein adsorption (c, d and e) to the following molecular assemblies: molecular assemblies formed from stearyl palmitate or cholesterol molecules, or molecular assemblies formed from stearyl palmitate and cholesterol molecules in different mixing ratios. 100 / 0 = 100 wt% stearyl palmitate + 0 wt% cholesterol; 99 / 1 = 99wt% stearyl palmitate + 1wt% cholesterol; 90 / 10 = 90 wt% stearyl palmitate + 10 wt% cholesterol; 50 / 50 =50 wt% stearyl palmitate + 50 wt% cholesterol; 0 / 100 = 0 wt% stearyl palmitate + 100 wt% cholesterol). In the experiments conducted, it was investigated whether the adhesion-reducing properties of the cholesterol molecular assembly were preserved when a mixed molecular assembly was produced from cholesterol molecules and a second component (stearyl palmitate) that did not have adhesion-reducing properties. The experiments were conducted using two different bacterial species (Staphylococcus epidermidis[a] and Escherichia coli[b]), two different protein species (bovine serum albumin[c] and lysozyme[d]), and a complex protein mixture (10% fetal bovine serum[e]). Figure 3 Images a and b plot the normalized counts of bacteria found on their respective surfaces after a one-hour incubation period (normalized relative to the control surface – silica [SiO2]). Images c, d, and e plot the absolute adsorbed protein mass on their respective surfaces (determined by measurement using an oscillating quartz microbalance). In measurements of bacterial adhesion (Images a and b), it was found that even a 10% wt% cholesterol molecule in the mixed molecular assembly resulted in reduced bacterial adhesion compared to a molecular assembly with 100 wt% cholesterol molecules. On the other hand, in measurements of protein adsorption (Images c, d, and e), it was found that even a 1% wt% cholesterol molecule in the mixed molecular assembly resulted in reduced bacterial adhesion compared to a molecular assembly consisting of 100 wt% cholesterol molecules.

[0039] Cholesterol SCL dynamically adapts to the polarity of its environment. The ability of cholesterol molecules 2 within molecular assemblies 1 of layered structure 3 to reorient themselves according to the polarity of the surrounding medium was detected by dynamic contact angle measurement and force spectroscopy based on atomic force microscopy.

[0040] Force spectroscopy measurements were performed using either hydrophobic colloidal probes or single *E. coli* cells immobilized on the tips of colloidal probes. Both types of probes were pressed onto the surface of cholesterol SCLs immersed in an aqueous solution at different time intervals. The resulting interaction forces were quantified, and it was found that the interaction forces continuously increased with contact time, demonstrating the reorientation of the nonpolar portions of the cholesterol molecules along the interfacial direction (to maximize hydrophobic interactions). When contact was interrupted, the interface returned to its initial state upon contact with water, indicating that the reorientation process could be repeated multiple times.

[0041] When the water droplet was removed immediately after application, dynamic contact angle measurements on the cholesterol SCL in air yielded similarly high advancing and retreating water contact angles. These results indicate that the nonpolar portions of the cholesterol molecules at the interface layer initially oriented towards the interface, while the polar portions oriented inward. However, if the water droplet was held on the surface for approximately 20 seconds after application and then removed, strong pinning of the three-phase contact line was observed, indicating that the interface is hydrophilic. Therefore, during the 20-second wait, the cholesterol molecules underwent reorientation, at which point their polar portions pointed towards the interface. This process is also reversible.

[0042] The reorientation fluctuations at the cholesterol-containing SCL interface are the cause of entropy repulsion. It has been demonstrated that the anti-adhesion properties of cholesterol-containing SCLs are related to their dynamic adaptation as a response to changes in environmental polarity. It can be hypothesized that entropy-driven orientation fluctuations of cholesterol molecules at the interface mechanically link these characteristics. Adsorption of any biomolecule or accumulation of (bacterial) cells requires adaptation to the orientation (polarity) of the SCL interface, which limits the orientation state of cholesterol and thus reduces the entropy of the system. Protein adsorption of cholesterol SCLs has been observed to decrease as the temperature increases from 15°C to 40°C.

[0043] The discovered entropy bioadhesion barrier is generated by a reorientation process at the cholesterol-containing SCL interface, which enables many technological applications.

[0044] The results indicate that cholesterol self-organizes within molecular assemblies, which can limit bioadhesion through entropy effects. The combination of the amphiphilic nature of cholesterol molecules and their efficient assembly in layered structures produces slow, adaptive, and cooperative interfacial migration of assemblies, considered a prerequisite for significant entropy repulsion.

[0045] List of reference numerals

Claims

1. A molecular assembly (1) on a solid surface (5). in, The molecular assembly (1) comprises a layer structure (3) of cholesterol molecules (2) deposited on the solid surface (5) by spin coating from a chloroform solution containing cholesterol molecules (2). Among them, the interface (4) of the layer structure (3) that is away from the solid surface (5) is in contact with the aqueous environment; Wherein, the cholesterol molecule (2) is oriented perpendicular to the interface (4) of the layer structure (3); and Cholesterol molecules (2) arranged in the layer structure (3) at the interface (4) spontaneously reorient when in contact with the aqueous environment.

2. The molecular assembly (1) according to claim 1, wherein, The layer structure (3) is a multilayer structure of cholesterol molecule (2).

3. The molecular assembly (1) according to claim 1, wherein, The thickness of the layer structure (3) is 15 nm.

4. The molecular assembly (1) according to claim 1, wherein, The cholesterol molecule (2) is stigmasterol, cholecalciferol and / or retinol.

5. The molecular assembly (1) according to claim 1 further comprises up to 99 wt% non-amphiphilic molecules.

6. The molecular assembly (1) according to claim 5, wherein, The non-amphiphilic molecule is stearyl palmitate.

7. The molecular assembly (1) according to any one of claims 1 to 6, wherein, The molecular assembly is configured to reduce protein adhesion.

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