Copolymer Surface Research Articles

Modification of surface topographies to inhibit candida biofilm formation.

The rise of infections associated with indwelling medical devices is a growing concern, often complicated by biofilm formation leading to persistent infections. This study investigates a novel approach to prevent Candida albicans attachment on the surface by altering surface topography. The research focuses on two distinct surface topographies: symmetry (squares) and non-symmetry (lines), created through a direct laser photolithography process on a Cyclic olefin copolymer (COC) surface. The wettability of these patterned surfaces was then examined immediately after fabrication and plasma treatment to mimic the sterilization process of indwelling devices through UV plasma. The results reveal directional wettability in the line pattern and size-dependent wettability in both square and line patterns. Candida albicans were cultured on these surfaces to assess the efficacy of the topography in preventing biofilm formation. The study demonstrates that symmetry and non-symmetry pattern topography inhibit biofilm formation, providing a promising strategy for mitigating Candida-associated infections on medical devices. The research sheds light on the potential of surface modification techniques to enhance the biocompatibility of medical devices and reduce the risk of biofilm-related infections.

Exploring the Application of Advanced Chromatographic Methods to Characterize the Surface Physicochemical Properties and Transition Phenomena of Polystyrene-b-poly(4-vinylpyridine)

The linear diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-P4VP) is an important copolymer recently used in many applications such as optoelectronics, sensors, catalysis, membranes, energy conversion, energy storage devices, photolithography, and biomedical applications. (1) Background: The surface thermodynamic properties of PS-P4VP copolymers are of great importance in many chemical and industrial processes. (2) Methods: The inverse gas chromatography (IGC) at infinite dilution was used for the experimental determination of the retention volumes of organic solvents adsorbed on copolymer surfaces as a function of temperature. This led to the variations in the free energy of interaction necessary to the evaluation of the London dispersive and polar acid–base surface energies, the polar enthalpy and entropy, the Lewis acid–base constants, and the transition temperatures of the PS-P4VP copolymer. (3) Results: The application of the thermal Hamieh model led to an accurate determination of the London dispersive surface energy of the copolymer that showed non-linear variations versus the temperature, highlighting the presence of two transition temperatures. It was observed that the Lewis acid–base parameters of the copolymer strongly depend on the temperature, and the Lewis base constant of the solid surface was shown to be higher than its acid constant. (4) Conclusions: An important effect of the temperature on the surface thermodynamic properties of PS-P4VP was proven and new surface correlations were determined.

Amphiphilic diblock copolymers of polyisobutylene-b-poly(2-ethyl-2-oxazoline) via cationic polymerization

A series of amphiphilic polyisobutylene-b-poly (2-ethyl-2-oxazoline) (PIB-b-PEOX) diblock copolymer/Ag nanoparticle composites were successfully in-situ synthesized via cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOX) with high initiation efficiency by using allyl bromide end functionalized polyisobutylene (PIB-allylBr) as a macroinitiator and AgClO4 as a coinitiator. The microphase separation formed in the resulting PIB-b-PEOX diblock copolymers due to the thermodynamic imcompability of hydrophilic PEOX segments and hydrophobic PIB segments. The micromorphology of phase separation is dependent on the copolymer composition, in which sea-island micromorphology formed for PIB118-b-PEOX80 and bicontinuous phase micromorphology formed for PIB118-b-PEOX97. The micelles with nano-scale size in the range of 15–80 nm and having high drug loading rate of ca. 48.9 % can be formed by self-assembly of the amphiphilic diblock copolymers in n-hexane. The drug cumulative release rate can be increased with an increase in the proportion of PEOX segments, due to the strong interaction between ibuprofen and the PEOX segments. The hydrophilicity of the PIB-b-PEOX diblock copolymer surfaces can be improved after ethanol vapor induction. The PIB-b-PEOX diblock copolymers behave biocompatibility and good anti-protein adsorption property. The amphiphilic PIB-b-PEOX diblock copolymer/Ag nanoparticle composites exhibit high antibacterial efficiency for Gram-negative bacterium (E. coli) and Gram-positive bacterium (S. aureus). To the best of our knowledge, this is the first example of PIB-b-PEOX diblock copolymer/Ag nanoparticle (6.4 ± 2.6 nm) composites synthesized in-situ with good biocompatibility, anti-protein adsorption, and antibacterial properties, which would have potential applications for drug delivery and anti-protein coating in biomedical areas.

Prediction and investigation of water repeated absorption and release properties of superabsorbent polymers during the dry-wet cycles in different solutions

Superabsorbent polymers (SAP) with a three-dimensional cross-linked network structure are used in the concrete field due to their good water absorption and water retention properties. The changes of its repeated water absorption and release properties have an important impact on crack healing, but there is still a lack of relevant research. This study mainly uses the tea-bag method to explore the repeated water absorption and release behavior of sodium polyacrylate and polyacrylic acid-acrylamide copolymers in deionized water, cement filtrate, and saturated calcium hydroxide solution. The quantitative analysis of the change in the peak area of the water-absorbing functional group was performed by fourier transform infrared spectroscopy. The morphology and elements of SAP under different dry-wet cycles were analyzed by scanning electron microscope-energy spectrum analysis. The repeated swelling behavior of SAP was predicted using the classical models. The results showed that the repeated water absorption performance of SAP gradually decreased with the increase of the number of wet-dry cycles. The slope of the curve for the second-order equation gradually increases, and the peak area corresponding to the carboxyl functional group also gradually increases. And the rate and amount of water release gradually increase. For sodium polyacrylate, with the increase in the number of wet-dry- cycles, the increase in the content of calcium, magnesium, and aluminum elements is accompanied by a significant decrease in the content of sodium elements. In contrast, the calcium content on the surface of polyacrylic acid-acrylamide copolymer increased, but the sodium content only slightly decreased.

Synthesis of triphenol‐diamine‐type hyperbranched benzoxazine and improvement of thermal properties and toughness of typical benzoxazines

AbstractA series of triphenol‐diamine‐type hyperbranched benzoxazines are synthesized by using polyformaldehyde, 1,1,1‐tri(4‐hydroxyphenyl) ethane, and primary amines such as p‐phenylenediamine, 4,4′‐diaminodiphenylmethane, polyetheramine, and bifuranocyclic diamine via Mannich condensation. Then, copolymers with bifunctional benzoxazine (BA‐a) are prepared to obtain superior properties. The polymerization behavior of the copolymers examined using a differential scanning calorimeter and a Fourier transform infrared indicates that the introduction of hyperbranched benzoxazines facilitates the benzoxazine curing reaction, decreasing the onset and peak temperatures of the curing process. Thermogravimetric analysis results suggest the cured hyperbranched benzoxazine demonstrates good thermal stability and can improve the heat resistance of benzoxazine. In addition, dynamic mechanical analysis suggests the glass transition temperature of the copolymers with BA‐a was increased after copolymerization, thus making all the copolymers obtain higher service temperatures. The test results from the universal testing machine and the fracture morphologies of copolymers indicate the hyperbranched benzoxazines with branched structures cause dendritic folds to appear on the surface of copolymers upon polymerization, preventing rapid cracking and spreading of the thermoset resin by dissipating more impact energy through this irregular dendritic appearance, thus obtaining strength and toughness superior to that of BA‐a resins.

Patterning of COC Polymers by Middle‐Energy Ion Beams for Selective Cell Adhesion in Microfluidic Devices

AbstractMicrofluidic devices play a crucial role in advanced cell biology applications, including cell separations, cultivations, migration and interaction studies, diagnostic devices, and organ‐on‐chips. One of the frequent purposes of such devices is the ability to selectively address the attachment of cells at defined locations on the surface. This study explores the application of middle‐energy carbon, oxygen, and nitrogen ions to locally modify the surface of cyclic olefin copolymer (COC) thermoplastic material, allowing selective cell growth on patterned polymer surfaces. The investigation considers ion element type, ion beam energy, and ion irradiation fluence, analyzing their influence on the modification effect. Characterization of the modified surfaces involves various surface‐analytical methods such as contact angle, energy dispersive spectroscopy (SEM‐EDX), atomic force microscopy (AFM), x‐ray photoelectron spectroscopy (XPS), rutherford backscattering spectrometry (RBS), and elastic recoil detection analysis (ERDA). The study extends to practical aspects, with a representative cancer cell line, MCF‐7, grown on the patterned surface to evaluate the degree of selective attachment. Additionally, the stability of the irradiated patterns is tested under elevated temperatures beyond the glass transition temperature (Tg), demonstrating the compatibility of the approach with hot embossing technology. The findings underscore the potential of ion beam treatment for COC in cell‐biology‐related applications, offering insights into surface modification techniques for enhanced functionality in microfluidic devices.

Self-Assembled Block Copolymers as a Facile Pathway to Create Functional Nanobiosensor and Nanobiomaterial Surfaces.

Block copolymer (BCP) surfaces permit an exquisite level of nanoscale control in biomolecular assemblies solely based on self-assembly. Owing to this, BCP-based biomolecular assembly represents a much-needed, new paradigm for creating nanobiosensors and nanobiomaterials without the need for costly and time-consuming fabrication steps. Research endeavors in the BCP nanobiotechnology field have led to stimulating results that can promote our current understanding of biomolecular interactions at a solid interface to the never-explored size regimes comparable to individual biomolecules. Encouraging research outcomes have also been reported for the stability and activity of biomolecules bound on BCP thin film surfaces. A wide range of single and multicomponent biomolecules and BCP systems has been assessed to substantiate the potential utility in practical applications as next-generation nanobiosensors, nanobiodevices, and biomaterials. To this end, this Review highlights pioneering research efforts made in the BCP nanobiotechnology area. The discussions will be focused on those works particularly pertaining to nanoscale surface assembly of functional biomolecules, biomolecular interaction properties unique to nanoscale polymer interfaces, functionality of nanoscale surface-bound biomolecules, and specific examples in biosensing. Systems involving the incorporation of biomolecules as one of the blocks in BCPs, i.e., DNA-BCP hybrids, protein-BCP conjugates, and isolated BCP micelles of bioligand carriers used in drug delivery, are outside of the scope of this Review. Looking ahead, there awaits plenty of exciting research opportunities to advance the research field of BCP nanobiotechnology by capitalizing on the fundamental groundwork laid so far for the biomolecular interactions on BCP surfaces. In order to better guide the path forward, key fundamental questions yet to be addressed by the field are identified. In addition, future research directions of BCP nanobiotechnology are contemplated in the concluding section of this Review.

Cell adhesion behavior of poly(l‐lactide‐co‐glycolide)‐poly(1,5‐dioxepan‐2‐one) random multiblock copolymers

AbstractAlthough bioabsorbable polymers are promising implant materials, implanting hydrophobic polymers induces platelet adhesions and subsequent thrombus formation. We recently reported that a multiblock copolymer composed of poly(l‐lactide‐co‐glycolide) (PLGA) and poly(1,5‐dioxepan‐2‐one) (PDXO) exhibited antiplatelet adhesive behavior. In this study, the cell adhesion behaviors of PLGA and PDXO random multiblock copolymers (PLGA−PDXO RMBCs) were examined. All the RMBCs showed antiplatelet adhesion behavior, and the copolymers containing 40 or 51 mol% of the PDXO component showed good antiplatelet adhesive behavior. Good culture behavior was observed for HeLa cells, but human umbilical vein endothelial cells (HUVECs) proliferation was poor on PLGA−PDXO RMBC surfaces. The cell attachment inhibition studies revealed that both integrin‐dependent and integrin‐independent interactions worked for HeLa cell culture, whereas only integrin‐dependent interactions played an important role for HUVEC culture proliferation on copolymer surfaces. The findings of this study revealed the unique cell‐selective adhesion behavior of PDXO containing multiblock polymers—being nonadhesive to platelets and HUVECs, and adhesive to HeLa cells.

Designing of tragacanth gum-poly(2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) and poly(acrylamide) based hydrogels for drug delivery and wound dressing applications

Bioactive tragacanth gum (TG) was functionalized by covalent crosslinking of poly[2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (PMEDSAH) to design network structure in form of hydrogel wound dressings (HWD). These copolymers were encapsulated with antibiotic drug vancomycin to enhance wound healing potential of the dressings. The copolymers were characterized by SEM, AFM, FTIR, 13C NMR, XRD, and TGA-DSC analysis. SEM demonstrated uneven heterogeneous morphology and AFM revealed rough surface of copolymer. Inclusion of synthetic component into HD was confirmed by FTIR and 13C NMR. Hydrogel dressings absorbed 8.49 ​± ​1.03 ​g/g simulated wound fluid and exhibited non-hemolytic (3.7 ​± ​0.02 % hemolytic potential) and antioxidant (37.42 ​± ​1.54 ​% free radical scavenging in DPPH assay) properties. Polymers required 35.0 ​± ​5.0 ​mN detachment force to get it detach from the mucosal surface during mucoadhesive test. Tensile strength was found to be 1.88 ​± ​0.13 ​N/mm2 during mechanical stability test. Hydrogel dressings were permeable to O2/H2O and impermeable to microbes. Release of drug vancomycin occurred through non-Fickian diffusion mechanism and release profile was best described by Korsmeyer-Peppas kinetic model. Overall, these results revealed that these hydrogels could be explored as materials for hydrogel wound dressings.

Photoresponse of new azo pyridine functionalized poly(2-hydroxyethyl methacrylate-co-methyl methacrylate)

A new azo polymer containing photoisomerizable azo pyridine functionalities was synthesized via Mitsunobu reaction of 4-(4-hydroxyphenylazo)pyridine with poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (p(HEMA-co-MMA)) for creating new photochromic materials. The resulting polymer with azo pyridine side groups was characterized for structural, thermal, and optical properties. UV–vis, 1H NMR and IR spectroscopies confirmed that all hydroxyl groups in p(HEMA-co-MMA) were substituted with azo dye. The obtained azo copolymer exhibited high thermal stability (around 240 °C) and a glass transition temperature (113 °C), promising for applications. The trans-to-cis isomerization upon UV irradiation and the thermal back reaction of the azo chromophore in the copolymer in the solid state was studied. A photostationary state with 50% content of cis-isomers upon 6 min of UV irradiation was reached, and during 48 h dark relaxation at ambient temperature, all cis-isomers converted to the trans form. Additionally, the possibility of efficient photogeneration of surface relief gratings with high amplitude of azo copolymer surface modulation was demonstrated.

Single-step immobilization of hydroxyapatite on fluoropolymer surfaces for enhanced cell adhesion

Herein, we report a single-step immobilization of hydroxyapatite (HAp) on the surface of poly(vinylidene fluoride) copolymer. This method utilizes the ability of fluoropolymer to undergo a limited swelling in acetone/water mixture followed by an entrapment of HAp on its surface. We found that while acetone/water ratio does not affect the thickness of HAp-containing layer, an increase in acetone content results in higher amounts of calcium and phosphorus found in modified area. HAp immobilization not only improved the hydrophilicity of the poly(vinylidene fluoride) copolymer surface but also contributed to enhanced cell adhesion (0.8 ± 0.4 % for the fluoropolymer surface vs. 86.9 ± 9.1 % for the modified fluoropolymer surface) and viability (increased by up to 30 %). Overall, this method represents a potent strategy for the modification of fluoropolymers which allows for the fabrication of bioactive implants using standard laboratory equipment.

Constructing a Comprehensive Nanopattern Library through Morphological Transitions of Block Copolymer Surface Micelles via Direct Solvent Immersion.

This study establishes a comprehensive library of nanopatterns achievable by a single block copolymer (BCP), ranging from spheres to complex structures like split micelles, flower-like clusters, toroids, disordered micelle arrays, and unspecified unique shapes. The ordinary nanostructures of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) surface micelles deposited on a SiOx surface undergo a unique morphology transformation when immersed directly in solvents. Investigating parameters such as immersion solvents, BCP molecular weight, substrate interactions, and temperature, this work reveals the influence of these parameters on the thermodynamics and kinetics governing the morphology transformation. Additionally, the practical application of BCP nanopattern templates for fabricating metal nanostructures through direct solvent immersion of surface micelles is demonstrated. This approach offers an efficient and effective method for producing diverse nanostructures, with the potential to be employed in nanolithography, catalysts, electronics, membranes, plasmonics, and photonics.

Hierarchical structure of poly(ε-caprolactone) crystals on its copolymer poly(l-lactide-co-ε-caprolactone) fibers

In crystallization, heterogeneous structures of copolymers are employed to establish a hierarchical architecture comprising two polymers, this typically occurs on the surface of block copolymers or blended polymers. While hierarchical structures in block copolymer fibers are well-established and widely utilized, achieving a regular hierarchical structure on random copolymer fibers is both meaningful and challenging. Here, we present a case of forming a hierarchical structure on the surface of the random copolymer poly(L-lactide-co-caprolactone) (PLCL)fibers. The (ε-caprolactone)(CL) polymer chain segments of the random copolymer are released on the surface of the modified copolymer fiber using sodium hydroxide. Subsequently, poly(ε-caprolactone)(PCL) forms a shish kebab-like crystalline structure under the guidance of the CL segments. The CL segments act as crystalline precursors to induce the formation of heterogeneous PLCL/PCL shish kebab structures. The variation of CL segments on the fiber changes with modification time, leading to the formation of crystalline lamellae of different sizes, which had been confirmed by characterization techniques such as scanning electron microscope (SEM), 1H NMR, X-ray photoelectron spectra (XPS), differential scanning calorimetry (DSC), etc. The implementation of this heterogeneous structure provides possibilities for the implementation of hierarchical structure in random copolymers.

Adhesion of methylene blue and malachite green to the surface of copolymer synthesized by grafting itaconic acid onto cellulose backbone – experimental and computational studies

This report describes the graft copolymerization of itaconic acid onto cellulose isolated from plantain trunk, using ammonium persulfate as initiator. Optimum grafting condition was established at 0.025 mol/L initiator concentration, 60 °C, 60 min grafting time and 3 g monomer mass. Characterization of the bio-materials indicated the success of the cellulose isolation and the grafting processes. At optimum grafting condition, about 34.0% grafting yield was obtained. With 25 mg of the co-polymer (PTC-g-IA), MB and MG uptake were 72.5 and 56.9 mg/g, respectively. These values represent about 2-fold sorption enhancement when compared with ungranted cellulose (PTC). The sorption process was influenced by solution pH, contact time, dye concentration and temperature. Modeling of the adsorption process indicated that the Pseudo-second-order kinetic model with R2 of unity and the Langmuir isothermal model (R2: 0.9622 (MB) and 0.9880 (MG)) best described the sorption process. Thermodynamic study described a feasible, spontaneous and exothermic process. Free energy value of 7.07 kJ/mol, and ΔH° values of < 20 kJ / mol , suggested a physisorption process. This was corroborated by the computational study which indicated non-covalent interactions between atoms in the dyes and the adsorbents. These interactions were stronger with the co-polymer. The interaction energies calculated for the dye-adsorbent interaction (-38.215, −52.868, −47.299 and −57.848 kJ/mol for PTC-MB, PTC-MG, PTC-g-IA-MB and PTC-g-IA-MG, respectively) show stronger interactions between PTC-g-IA and the dye molecules compared to pure cellulose in line with experimental observations. In overall, this study portrays the cellulose-based co-polymer as having the potential of easily removing MB and MG from wastewater.

Can antibody conjugated nanomicelles alter the prospect of antibody targeted therapy against schistosomiasis mansoni?

CLA (conjugated linoleic acid)-mediated activation of the schistosome tegument-associated sphingomyelinase and consequent disruption of the outer membrane might allow host antibodies to access the apical membrane antigens. Here, we investigated a novel approach to enhance specific antibody delivery to concealed surface membrane antigens of Schistosoma mansoni utilising antibody-conjugated-CLA nanomicelle technology. We invented and characterised an amphiphilic CLA-loaded whey protein co-polymer (CLA-W) as an IV injectable protein nanocarrier. Rabbit anti-Schistosoma mansoni infection (anti-SmI) and anti-Schistosoma mansoni alkaline phosphatase specific IgG antibodies were purified from rabbit sera and conjugated to the surface of CLA-W co-polymer to form antibody-conjugated-CLA-W nanomicelles (Ab-CLA-W). We investigated the schistosomicidal effects of CLA-W and Ab-CLA-W in a mouse model of Schistosoma mansoni against early and late stages of infection. Results showed that conjugation of nanomicelles with antibodies, namely anti-SmI, significantly enhanced the micelles' schistosomicidal and anti-pathology activities at both the schistosomula and adult worm stages of the infection resulting in 64.6%-89.9% reductions in worm number; 72.5-94% and 66.4-85.2% reductions in hepatic eggs and granulomas, respectively. Treatment induced overall improvement in liver histopathology, reducing granuloma size and fibrosis and significantly affecting egg viability. Indirect immunofluorescence confirmed CLA-W-mediated antigen exposure on the worm surface. Electron microscopy revealed extensive ultrastructural damage in worm tegument induced by anti-SmI-CLA-W. The novel antibody-targeted nano-sized CLA delivery system offers great promise for treatment of Schistosoma mansoni infection and control of its transmission. Our in vivo observations confirm an immune-mediated enhanced effect of the schistosomicidal action of CLA and hints at the prospect of nanotechnology-based immunotherapy, not only for schistosomiasis, but also for other parasitic infections in which chemotherapy has been shown to be immune-dependent. The results propose that the immunodominant reactivity of the anti-SmI serum, Schistosoma mansoni fructose biphosphate aldolase, SmFBPA, merits serious attention as a therapeutic and vaccine candidate.

Facile preparation of diblock copolymers as functional surfaces for protein chromatography

AbstractStationary phase plays a crucial role in the operation of a protein chromatography column. Conventional resins composed of acrylic polymers and their derivatives contribute to heterogeneity of the packing of stationary phase inside these columns. Alternative polymer combinations through customized surface functionalization schemes which consist of multiple steps using static coating techniques are well known. In comparison, it is hypothesized that single‐step scheme is sufficient to obtain porous adsorbents as stationary phase for tuning surface morphology and protein immobilization. To overcome the challenge of heterogeneous packing and ease of fabrication at laboratory scale, change in the form factor of separation materials has been proposed in the form of functional copolymer surfaces. In the present work, an amphiphilic, block copolymer, poly(methyl methacrylate‐co‐methacrylic acid) has been chosen and fully characterized for its potential usage in protein chromatography. Hydrophilicity of the acrylic copolymer and abundance of carboxyl groups inherently on the copolymer surface have been successfully demonstrated through contact angle measurements, Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) studies. Morphological studies indicate presence of a microporous region (nearly 1.3 μm average pore size) that could be beneficial as a cation exchange media as part of the stationary phase in protein chromatography.

Morphology and Mechanical Properties of High Density Polyethylene and Ethylene-Methyl Acrylate Copolymer Blends with Organoclay

In this research, the effect of ethylene-methyl acrylate copolymer (EMAC or EMAC30) and clay surface modified with aminopropyltriethoxysilane 0.5-5 wt% and octadecylamine 15-35 wt% (Clay-ASO) on the morphological, mechanical, and thermal properties of high density polyethylene (HDPE) were investigated. The polymer blends and composites were prepared by an internal mixer and then samples were molded by compression molding. The morphology analysis showed that the presence of fibrous surface at the specimen fracture surface of HDPE/EMAC30 blends. The phase morphology of HDPE blends with Clay-ASO 3, 5 and 7 phr was observed the phase separation of EMAC30 and aggregate of Clay-ASO at high EMAC30 content. Young’s modulus of HDPE/Clay-ASO composites increased with increasing Clay-ASO composites. The presence of Clay-ASO did not improve Young’s modulus and tensile strength of HDPE/EMAC30/Clay-ASO composites. The strain at break of HDPE/EMAC30 blends increased with increasing EMAC30 content. The incorporation of EMAC30 and Clay-ASO had no effect on the melting temperature of HDPE blends and composites, respectively. The percent crystallinity of HDPE/EMAC30 and HDPE/EMAC30/Clay-ASO was lower than that of pure HDPE. The addition of EMAC30 and Clay-ASO decreased the degradation temperatures of HDPE/EMAC30 blends and composites.

Design, fabrication, and characterization of picowell arrays on cyclic olefin copolymer surfaces generated with a 10.5 MeV N4+ ion microbeam

Handling of picoliter-to-nanoliter-scale volumes and objects has increasing importance in life sciences. This is the volume scale of cell extractions and individual living cells. Here, we introduce a method of generating a picoliter-scale device by direct writing of picowell arrays on a ZEONOR™ copolymer surface with high-energy medium-mass ion microbeam. Arrays of various microstructures were written in the sample using a microbeam of 10.5 MeV N4+ ions at various implanted ion fluences. The best array was obtained by implantation of annuli of 10 and 11 μm of inner and outer diameters with a fluence of 7.8 × 1012 ions/cm2.

Smart Copolymer Surface Derived from Geminized Cationic Amphiphilic Polymers for Reversibly Switchable Bactericidal and Self-Cleaning Abilities.

Bacterial adhesion and colonization on material surfaces pose a serious problem for healthcare-associated devices. Cationic amphiphilic polymer brushes are usually used as surface coatings in antibacterial materials to endow an interface with excellent bactericidal efficiency, but they are easily contaminated, which puts a great limitation on their application. Herein, novel antibacterial copolymer brush surfaces containing geminized cationic amphiphilic polymers (pAGC8) and thermoresponsive poly(N-isopropylacrylamide) polymers (pNIPAm) have been synthesized. Surface functionalization of polymer brushes was investigated by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, atomic force microscopy, and water contact angle measurements. A proportion of AGC8 and NIPAm units in copolymer brushes has been adjusted to obtain a high-efficiency bactericidal surface with minimal interference to its self-cleaning property. The killing and releasing efficiency of the optimized surface simultaneously reached up to above 80% for both Staphylococcus aureus and Escherichia coli bacteria, and the bactericidal and self-cleaning abilities are still excellent even after three kill-release cycles. Such a novel copolymer brush system provides innovative guidance for the development of high-efficiency antibacterial materials in biomedical application.

Characterization of a Model Bioreactive Membrane for the Simultaneous Separation and Hydrolysis of Lipopolysaccharides

The design of functionalized selective layers to develop novel membranes is essential to provide potential solutions that meet the continuously growing demand of providing safe water. Herein, we present the interfacial response of an enzymatic thin-film composite (E-TFC) membrane displaying dual functionality and fabricated as a proof-of-concept for both efficient lipopolysaccharide (LPS) separation and ester bond hydrolysis. The enzymatic membrane model was constructed by employing lipase b from Candida antarctica (CALB) covalently coupled via chemically activated bisepoxide groups onto the surface of the di-block copolymer polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) layer. Our results show a complete rejection of size-excluded LPS molecules when using the fabricated E-TFC membrane in a forward osmosis (FO) application. Moreover, the immobilized enzyme was able to retain 97% of its enzymatic activity when using 4-nitrophenyl acetate (pNPA) and up to 74% to liberate free fatty acids from LPS molecules within the feed side of the FO system. This work provides fundamental insights into new emerging functional biomaterials that find applications in hybrid catalytic filtration processes that also selectively remove LPS molecules from water sources.