Antibacterial Coatings Research Articles

Self-controllable proteinic antibacterial coating with bacteria-triggered antibiotic release for prevention of periprosthetic infection

Periprosthetic infection is a devastating postimplantation complication in which a biofilm layer harboring invasive microorganisms forms around orthopedic implants, leading to severe implant failure and patient morbidity. Despite the development of several infection-triggered antibiotic release approaches, most current antibacterial coatings are susceptible to undesired antibiotic leakage or mechanical disintegration during prosthesis installation. Herein, we propose a self-controllable proteinic antibacterial coating capable of both long-lasting adherence onto titanium implant substrates over the implant fixation period and instantaneous bacterial eradication. Importantly, the pH-dependent reversible metal coordination of mussel adhesive protein (MAP) enabled bacterial concentration-dependent antibiotic delivery in response to infection-induced acidification. In addition, the MAP coating exhibited superior self-healable adhesive properties and scratch resistance, which enabled to avert issues associated with mechanical damages, including peeling and cracking, often occurring in conventional implant coating systems. The gentamicin-loaded MAP coating exhibited complete inhibition of bacterial growth in vivo against Staphylococcus aureus penetrations during implantation surgery (immediate infection) and even 4 weeks after implantation (delayed infection). Thus, our antibiotic-loaded MAP hydrogel coating can open new avenues for self-defensive antibiotic prophylaxis to achieve instant and sustainable bacteriocidal activity in orthopedic prostheses.© 2017 Elsevier Inc. All rights reserved.

Biomimetic Coatings in Implant Dentistry: A Quick Update.

Biomimetic dental implants are regarded as one of the recent clinical advancements in implant surface modification. Coatings with varying thicknesses and roughness may affect the dental implant surface's chemical inertness, cell adhesion, and antibacterial characteristics. Different surface coatings and mechanical surface changes have been studied to improve osseointegration and decrease peri-implantitis. The surface medication increases surface energy, leading to enhanced cell proliferation and growth factors, and, consequently, to a rise in the osseointegration process. This review provides a comprehensive update on the numerous biomimetic coatings used to improve the surface characteristics of dental implants and their applications in two main categories: coating to improve osseointegration, including the hydroxyapatite layer and nanocomposites, growth factors (BMPs, PDGF, FGF), and extracellular matrix (collagen, elastin, fibronectin, chondroitin sulfate, hyaluronan, and other proteoglycans), and coatings for anti-bacterial performance, covering drug-coated dental implants (antibiotic, statin, and bisphosphonate), antimicrobial peptide coating (GL13K and human beta defensins), polysaccharide antibacterial coatings (natural chitosan and its coupling agents) and metal elements (silver, zinc, and copper).

The 2D Ti3C2Tx MXene-enabled self-cleaning and self-sterilizing lacquer coatings for offset printing

Microbiologically contaminated surfaces pose a severe threat to human health. Antibacterial coatings that effectively destroy pathogens in-situ under ambient conditions are candidates to overcome this issue. In this work, we report self-sterilizing lacquer coatings enabled by the addition of novel 2D Ti3C2Tx MXene, showing excellent photocatalytic and antimicrobial properties. The prepared facile MXene-enriched formulations based on air-drying and UV-curable lacquer dispersions were used to coat the opaque plastic sheets. The Ti3C2Tx MXene content was optimized to ensure a minimal agglomeration of flakes in a lacquer coating, as validated by stability, morphology, and structure analyses. We confirmed the uniform distribution of 2D Ti3C2Tx MXene in the coatings with energy dispersive spectroscopy (EDS) mapping. Superior optical properties of the protective lacquer coatings, added with efficient light absorption, enabled their self-cleaning from the adsorbed methylene blue coloring contaminant. This photocatalytic activity was further utilized for antimicrobial action. Under dark conditions, the protective lacquer coatings showed biostatic properties while in simulated daylight conditions, they were self-sterilizing against potentially pathogenic model bacteria such as Escherichia coli and Staphylococcus aureus. Altogether, our findings gave promise for using MXenes in daily life applications.

Recent Progress in antibacterial hydrogel coatings for targeting biofilm to prevent orthopedic implant-associated infections.

The application of orthopedic implants for bone tissue reconstruction and functional restoration is crucial for patients with severe bone fractures and defects. However, the abiotic nature of orthopedic implants allows bacterial adhesion and colonization, leading to the formation of bacterial biofilms on the implant surface. This can result in implant failure and severe complications such as osteomyelitis and septic arthritis. The emergence of antibiotic-resistant bacteria and the limited efficacy of drugs against biofilms have increased the risk of orthopedic implant-associated infections (OIAI), necessitating the development of alternative therapeutics. In this regard, antibacterial hydrogels based on bacteria repelling, contact killing, drug delivery, or external assistance strategies have been extensively investigated for coating orthopedic implants through surface modification, offering a promising approach to target biofilm formation and prevent OIAI. This review provides an overview of recent advancements in the application of antibacterial hydrogel coatings for preventing OIAI by targeting biofilm formation. The topics covered include: (1) the mechanisms underlying OIAI occurrence and the role of biofilms in exacerbating OIAI development; (2) current strategies to impart anti-biofilm properties to hydrogel coatings and the mechanisms involved in treating OIAI. This article aims to summarize the progress in antibacterial hydrogel coatings for OIAI prevention, providing valuable insights and facilitating the development of prognostic markers for the design of effective antibacterial orthopedic implants.

Evaluation of In Vivo Biocompatibility in Preclinical Studies of a Finger Implant Medical Device Correlated with Mechanical Properties and Microstructure.

The aim of the experiment was to evaluate the biocompatibility of four 3D-printed biomaterials planned for use in the surgical treatment of finger amputees: Ti-6Al-4 V (Ti64), ZrO2-Al2O3 ceramic material (ATZ20), and osteoconductive (anodized Ti64) and antibacterial (Hydroxyapatite, HAp) coatings that adhere well to materials dedicated to finger bone implants. The work concerns the correlation of mechanical, microstructural, and biological properties of dedicated materials. Biological tests consisted of determining the overall cytotoxicity of the organism on the basis of in vivo tests carried out in accordance with the ISO 10993-6 and ISO 10993-11 standards. Clinical observations followed by diagnostic examinations, histopathological evaluation, and biochemical characterization showed no significant differences between control and tested groups of animals. The wound healed without complication, and no pathological effects were found. The wear test showed the fragility of the hydroxyapatite thin layer and the mechanical stability of the zirconia-based ceramic substrate. Electron microscopy observations revealed the layered structure of tested substrates and coatings.

Oxidative crosslinking induced self-reinforcing waterborne polyurethane with tunable structure as multi-synergistic antibacterial biomimetic composite coating

Waterborne polyurethane (WPU) coatings with antibacterial properties have attracted extensive attention. Herein, we proposed a molecular design strategy was used to establish a series of castor oil/tung oil based WPU antibacterial coatings. By introducing conjugated double bonds of tung oil into WPU skeleton, electrostatic interaction by zwitterion and bacterial division inhibition by conjugated double bonds achieved the synergistic antibacterial effects. To our delight, inspired by lotus leaves, the scanning electron microscope test revealed the bionic micro-nano embedded structure was constructed on the surface of WPU using siloxane-modified nanocellulose (CNC@MTES). The destruction of the phosphorus layers and superhydrophobicity grant the material to have quadruple synergistic antibacterial effects. The antibacterial rates of WPU coatings on E. coli and S. aureus were more than 99.6% and played the mildew protection effect. What's more, peroxy bond formed by unique oxidative cross-linking induced self-reinforcing to enhanced the mechanical properties (the stress and Young's modulus of coating enhanced by 122.06% and 2368% respectively). Strong bonding between CNC@MTES and WPU ensured the durability of the coating, which was still effectively antibacterial and hydrophobic after 400 friction cycles. This research offered an innovative and effective method for coating to be widely used in product packaging, medical devices, smart glass and other fields.

Functional Zwitterionic Polyurethanes: State-of-the-Art Review.

Recent advancements in bioengineering and medical devices have been greatly influenced and dominated by synthetic polymers, particularly polyurethanes (PUs). PUs offer customizable mechanical properties and long-term stability, but their inherent hydrophobic nature poses challenges in practically biological application processes, such as interface high friction, strong protein adsorption, and thrombosis. To address these issues, surface modifications of PUs for generating functionally hydrophilic layers have received widespread attention, but the durability of generated surface functionality is poor due to irreversible mechanical wear or biodegradation. As a result, numerous researchers have investigated bulk modification techniques to incorporate zwitterionic polymers or groups onto the main or side chains of PUs, thereby improving their hydrophilicity and biocompatibility. This comprehensive review presents an extensive overview of notable zwitterionic PUs (ZPUs), including those based on phosphorylcholine, sulfobetaine, and carboxybetaine. The review explores their wide range of biomedical applications, from blood-contacting devices to antibacterial coatings, fouling-resistant marine coatings, separation membranes, lubricated surfaces, and shape memory and self-healing materials. Lastly, the review summarizes the challenges and future prospects of ZPUs in biological applications.

Highly Adhesive and Self-Healing Zwitterionic Hydrogels as Antibacterial Coatings for Medical Devices.

Bacterial infection of medical devices has caused incalculable losses to maintenance costs and health care. A single coating with antibacterial function cannot guarantee the long-term use of the device, because the coating will be damaged and fall off during reuse. To solve this problem, the development of coatings with high adhesion and self-healing ability is a wise direction. In this paper, a multifunctional polyzwitterionic antibacterial hydrogel coating (PZG) composed of amphozwitterion monomer, anionic monomer, and quaternary ammonium cationic monomer was synthesized by dipping UV photoinitiated polymerization. The structure of PZGs was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. Ascribing to the hydrogel internal electrostatic interaction, hydrogen bond, and cation-π interaction, the obtained PZGs exhibited high ductility (>1200% strain) and appropriate strength (>189 kPa). Remarkably, PZGs could also adhere firmly on different substrates through noncovalent interaction, and their adhesion could be controlled by adjusting the amount of zwitterionic. Reversible physical interactions in polymer networks endowed hydrogels with excellent self-healing properties. In addition, PZGs exhibit good antibacterial activity and biocompatibility due to the synergistic effect of quaternary ammonium cation and amphozwitterion monomer. This work provides a multifunctional antibacterial coating for medical equipment and has broad application prospects in the biomedical field.

Microstructural and tribological properties of TiO2/Ag multilayer coatings using magnetron sputtering technique for potential applications in non-permanent implants

The development of ideal surfaces for metal implants and osseous stabilization devices requires consideration of various phenomena. These include the formation of bacterial biofilms on the surface, which can lead to infections or rejection of the device. Additionally, the overgrowth of bone material around these devices can create a barrier to their removal once their function has been fulfilled. Due to this, the development of multilayer antibacterial coatings of TiO2/Ag on Ti6Al4V substrates was studied for potential use in non-permanent implants. Magnetron Sputtering technique, which provides significant control over the microstructural features was used to deposit 10 and 15 TiO2/Ag bilayers, resulting in coatings with a uniform and packed structure. Additionally, TiO2 monolayer was used as a comparative sample. Consequently, the properties of the developed systems were characterized using scanning electron microscopy/energy dispersive spectroscopy, Raman spectroscopy, X-ray diffraction, tribologic assays and surface properties such as rugosity and wettability. Experimental results confirm the presence of crystalline anatase in all systems and an increase both in thickness and roughness as the bilayer number increases compared to TiO2 monolayer coatings. Multilayer coatings evince decreased wettability and crystallinity with higher bilayer counts compared to the highly hydrophobic nature of Ti6Al4V substrates (>90°). Both systems, 10 and 15 multilayer coatings present a thickness of approximately 730 nm and improved hydrophilicity with contact angles of 68.5° and 55.2° respectively, while the TiO2 monolayer grew around 1300 nm and had a contact angle of 86.3° Finally, the tribological properties improve as the silver content on the surface increases as the noble metal tends to accumulate in nanoparticles on the outermost layers of the multilayer systems, exhibiting its solid lubricating effect, however, the wear rate increases for 15TiO2-Ag sample, as more Ag migrates, altering the coating microstructure.

One-step assembly of bimetal-phenolic networks for antifouling and antibacterial coatings

Titanium (Ti) and its alloys have been widely used as clinical implant biomaterials. However, protein adhesion and bacterial infection can negatively impact the efficacy of these implants. To combat this, a promising strategy is to develop a versatile coating on Ti materials that endows them with antifouling and antibacterial capabilities. This work focused on the development of a polydopamine (PDA) and poly(sulfobetaine methacrylate) (PSBMA) co-deposition coating on Ti substrates. The coating contained copper ions, iron ions, and catechol groups, which coordinated to assemble bimetal-phenolic networks (bMPNs). Digital imaging, SEM, AFM, XPS, water contact angle, and film thickness tests confirmed the success of the modification. The antibacterial properties of the coating were evaluated using Gram-positive Staphylococcus aureus, while the cytotoxicity of the coating on human umbilical vein endothelial cells was also examined. The results demonstrated an excellent improvement in hydrophilicity, antibacterial properties, and benign biocompatibility of the coated Ti substrate, making it suitable for bioimplants and medical devices.

Resveratrol-Encapsulated Glutathione-Modified Robust Mesoporous Silica Nanoparticles as an Antibacterial and Antibiofilm Coating Agent for Medical Devices.

The emergence of various lethal bacterial infections and their adherence to medical devices are major public health concerns. The increased bacterial exposure and titer are accompanied by the inappropriate use of antibiotics that sometimes lead to antibiotic resistance, and therefore, a drug-free antibacterial approach is required. Several nanoparticles (NPs) have been developed as antibacterial and antibiofilm coating agents, which can overcome different drug resistance mechanisms by inhibiting the important processes related to bacterial virulence potential. However, developing safe and biocompatible nanomaterials (NMs) for these applications has remained a major challenge due to their poorly understood mechanism of action. In this work, biogenic silica NPs were modified with glutathione (GSH) to form GSH@SNP (∼80 ± 15 nm) for targeting the bacterial cell surface and biofilm. GSH@SNP was loaded with resveratrol to obtain Res_GSH@SNP (∼124 ± 15 nm) that enhances the antibacterial activity of the NPs against Staphylococcus aureus and Escherichia coli by ∼51 and ∼49%, respectively, compared to GSH@SNP. Res_GSH@SNP is responsible for binding to the bacterial cell surface receptors that interrupt the cell membrane potential, leading to reactive oxygen species (ROS) generation, membrane disruption, and DNA damage and eventually resulting in antibacterial activity. Moreover, the antibiofilm activity of Res_GSH@SNP has been found to result from the interaction of the NPs with the abundant carbohydrates present on the biofilm surface. To check the practical utility of Res_GSH@SNP, these were further evaluated as an antibacterial and antibiofilm coating agent for urinary catheters and were found to be effective even after multiple washes. Res_GSH@SNP has been found to exhibit ∼80 ± 1.4% cytocompatibility toward fibroblast NIH-3T3 cells. Overall, this study is expected to pave the way for the development of biocompatible NP-based coating agents for medical devices.

Layer-by-Layer Coatings of Collagen-Hyaluronic acid Loaded with an Antibacterial Manuka Honey Bioactive Compound to Fight Metallic Implant Infections.

Implant-associated severe infections can result in catastrophic implant failures; thus, advanced antibacterial coatings are needed to combat infections. This study focuses on harnessing nature-inspired self-assembly of extracellular matrix (ECM)-like coatings on Ti alloy with a combination of jellyfish-derived collagen (J-COLL) and hyaluronic acid (HA) using our customized automated hybrid layer-by-layer apparatus. To improve the anti-infection efficacy of coatings, we have incorporated a natural antibacterial agent methylglyoxal (MGO, a Manuka honey compound) in optimized multilayer coatings. The obtainment of MGO-loaded multilayer coatings was successfully assessed by profilometry, contact angle, attenuated total reflectance (ATR)-Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. In vitro degradation confirmed the controlled release activity of MGO with a range of concentrations from 0.90 to 2.38 mM up to 21 days. A bacterial cell culture study using Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis) confirmed that the MGO incorporated within layers 7 and 9 had a favorable effect on preventing bacterial growth and colonization on their surfaces. An in vitro cytocompatibility study confirmed that MGO agents included in the layers did not affect or reduce the cellular functionalities of L929 fibroblasts. In addition, MGO-loaded layers with Immortalized Mesenchymal Stem Cells (Y201 TERT-hMSCs) were found to favor the growth and differentiation of Y201 cells and promote calcium nodule formation. Overall, these surface coatings are promising candidates for delivering antimicrobial activity with bone-inducing functions for future bone tissue engineering applications.

Electrosprayed zein nanoparticles as antibacterial and anti-thrombotic coatings for ureteral stents

Ureteral stents are among the most frequently used human implants, with urothelium trauma, blood clots, and bacterial colonization being their main reasons for failure. In this study, berberine-loaded zein (ZB) nanoparticles with high drug encapsulation efficiency (>90 %) were fabricated via electrospray on flat and 3D stainless steel structures. Physico-chemical characterization revealed that the ZB nanoparticles created a highly hydrophilic, antioxidant, and scratch-resistant continuous coating over the metal structure. Results showed that the drug release rate was faster at neutral pH (i.e., PBS pH 7.4) than in an artificial urine medium (pH 5.3) due to the different swelling behavior of the zein polymeric matrix. In vitro evaluation of ZB particles onto human dermal fibroblasts and blood cells demonstrated good cell proliferation and enhanced anti-thrombotic properties compared to bare stainless steel. The ability of the electrosprayed zein particles to resist bacterial adherence and proliferation was evaluated with Gram-negative (Escherichia coli) bacteria, showing high inhibition rates (−29 % and −46 % for empty and berberine-loaded particles, respectively) compared to the medical-grade metal substrates. Overall, the proposed composite coating fulfilled the requirements for ureteral applications, and can advance the development of innovative biocompatible, biodegradable, and antibacterial coatings for drug-eluting stents.

Construction of decorative, antibacterial, anti-aging and fire-retardant integrative coatings for wood substrates with super protective performances

To prevent the coatings applied in historical buildings from aging failure due to environmental factors, an integrative coating with decorative, antibacterial, weather-resistant and flame-retardant properties is particularly important in practical applications. The nanocomposite flame retardants named CPPBs are obtained from the successful grafting of the phosphate esters to the surface of cerium oxide nanoparticles, which are physically blended with film-forming polymer to construct integrative coating named MCPPBs. The results show that adding nano-CeO2 greatly strengthens the mechanical property, fire protection performances, weather resistance, antibacterial activity of the integrative coatings, and maintains high light transmittance in the meantime. Especially, when the addition of nano-CeO2 in flame retardant is 0.5 wt.%, the expansion ratio of the MCPPB3 coating increases to 65 and the char index reduces to 15.7cm3, concomitant with a high transparency of 80.3 %. By combining FTIR, SEM and EDS analyses, the MCPPBs char containing nano-CeO2 is compact and dense. In the accelerated aging test, the back equilibrium temperature of the MCPPB3 coating at 900 s is still less than 220 °C concomitant with a complete surface morphology after 6 aging cycles. In addition, the MCPPB3 coating exerts a negative effect on the growth of E. coli and S. aureus, and the antibacterial activities against E. coli and S. aureus are 92.8 % and 96.2 %, respectively.

Antibacterial Plasma Polymer Coatings on 3D Materials for Orthopedic Applications

AbstractCovalent biofunctionalization of implant surfaces using anti microbial agents is a promising approach to reducing bone infection and implant failure. Radical‐rich, ion‐assisted plasma polymerized (IPP) coatings enable surface covalent biofunctionalization in a simple manner; but until now, they are limited to only 2D surfaces. Here a new technology is demonstrated to create homogenous IPP coatings on 3D materials using a rotating, conductive cage that is negatively biased while immersed in RF plasma. Evidence is provided that under controlled energetic ion bombardment, this technology enables the formation of highly robust and homogenous radical‐rich coatings on 3D objects for subsequent covalent attachment of antimicrobial agents. To functionally apply this technology, the broad‐spectrum antimicrobial CSA‐90 is attached to the surfaces, where it retained potent antibacterial activity against Staphylococcus aureus. CSA‐90 covalent functionalization of stainless‐steel pins used in a murine model of orthopedic infection revealed the highly promising potential of this coating system to reduce S. aureus infection‐related bone loss. This study takes the previous research on plasma‐based covalent functionalization of 2D surfaces a step further, with important implications for ushering in a new dimension in the biofunctionalization of 3D structures for applications in bone implants and beyond.

Phytic Acid-Promoted Exfoliation of Black Phosphorus Nanosheets for the Fabrication of Photothermal Antibacterial Coatings.

Medical device-associated infections (MDAI) caused by planktonic pathogens are of serious concern worldwide due to the emergence of drug resistance resulting from continuous overuse or misuse of antibiotics. Therefore, the design of non-antibiotics-based treatment for MDAI is of crucial importance. Black phosphorus (BP), a novel 2D material, has recently received much attention owing to its remarkable physical, chemical, mechanical, and functional features. However, the intricacy of the fabrication process has severely hampered the development of BP in prospective applications. In this study, a simple and eco-friendly liquid-phase exfoliation method of phytic acid (PA)-promoted exfoliation of BP nanosheets (PA@BP NSs) is developed for their potential application in antibacterial photothermal therapy. To impart the antimicrobial effects, the polydimethylsiloxane surfaces are functionalized with quaternized polymer (polyquaternium-2 or PQ) and PA@BP NSs, leading to the formation of PA-BP-PQ composite coatings. In addition to the contact-killing antibacterial effect of the cationic PQ, the PA-BP-PQ coating exhibits remarkable near-infrared irradiation-triggered bactericidal effects with low cytotoxicity both in vitro and in vivo. This study proposes a simple liquid-phase exfoliation technique for the fabrication of BP NSs and a one-step approach for the construction of PA-BP-PQ composite coatings for bi-modal (contact-killing and photothermal) antimicrobial therapy.

Atomic Layer Deposition of Antibacterial Nanocoatings: A Review.

In recent years, antibacterial coatings have become an important approach in the global fight against bacterial pathogens. Developments in materials science, chemistry, and biochemistry have led to a plethora of materials and chemical compounds that have the potential to create antibacterial coatings. However, insufficient attention has been paid to the analysis of the techniques and technologies used to apply these coatings. Among the various inorganic coating techniques, atomic layer deposition (ALD) is worthy of note. It enables the successful synthesis of high-purity inorganic nanocoatings on surfaces of complex shape and topography, while also providing precise control over their thickness and composition. ALD has various industrial applications, but its practical application in medicine is still limited. In recent years, a considerable number of papers have been published on the proposed use of thin films and coatings produced via ALD in medicine, notably those with antibacterial properties. The aim of this paper is to carefully evaluate and analyze the relevant literature on this topic. Simple oxide coatings, including TiO2, ZnO, Fe2O3, MgO, and ZrO2, were examined, as well as coatings containing metal nanoparticles such as Ag, Cu, Pt, and Au, and mixed systems such as TiO2-ZnO, TiO2-ZrO2, ZnO-Al2O3, TiO2-Ag, and ZnO-Ag. Through comparative analysis, we have been able to draw conclusions on the effectiveness of various antibacterial coatings of different compositions, including key characteristics such as thickness, morphology, and crystal structure. The use of ALD in the development of antibacterial coatings for various applications was analyzed. Furthermore, assumptions were made about the most promising areas of development. The final section provides a comparison of different coatings, as well as the advantages, disadvantages, and prospects of using ALD for the industrial production of antibacterial coatings.

Reduced TiO2 Nanotubes/Silk Fibroin/ZnO as a Promising Hybrid Antibacterial Coating.

The current research aims to elucidate the influence of reduction process of TiO2 nanostructures on the surface properties of a bioinspired Ti modified implant, considering that the interface between a biomaterial surface and the living tissue plays an important role for this interaction. The production of reduced TiO2 nanotubes (RNT) with lower band gap is optimized and their performance is compared with those of simple TiO2 nanotubes (NT). The more conductive surfaces provided by the presence of RNT on Ti, allow a facile deposition of silk fibroin (SF) film using the electrochemical deposition method. This hybrid film is then functionalized with ZnO nanoparticles, to improve the antibacterial effect of the coating. The modified Ti surface is evaluated in terms of surface chemistry, morphology and roughness, wettability, surface energy, surface charge and antibacterial properties. Surface analysis such as SEM, AFM, FTIR and contact angle measurements were performed to obtain topographical features and wettability. FT-IR analysis confirms that SF was effectively attached to TiO2 nanotubes surfaces. The electrochemical deposition of SF and SF-ZnO reduced the interior diameter of nanotubes from ~85 nm to approx. 50-60 nm. All modified surfaces have a hydrophilic character.

Expanding the Scope of an Amphoteric Condensed Tannin, Tanfloc, for Antibacterial Coatings.

Bacterial infections are a common mode of failure for medical implants. This study aims to develop antibacterial polyelectrolyte multilayer (PEM) coatings that contain a plant-derived condensed tannin polymer (Tanfloc, TAN) with inherent antimicrobial activity. Tanfloc is amphoteric, and herein we show that it can be used as either a polyanion or a polycation in PEMs, thereby expanding the possibility of its use in PEM coatings. PEMs are ordinarily formed using a polycation and a polyanion, in which the functional (ionic) groups of the two polymers are complexed to each other. However, using the amphoteric polymer Tanfloc with weakly basic amine and weakly acidic catechol and pyrogallol groups enables PEM formation using only one or the other of its functional groups, leaving the other functional group available to impart antibacterial activity. This work demonstrates Tanfloc-containing PEMs using multiple counter-polyelectrolytes including three polyanionic glycosaminoglycans of varying charge density, and the polycations N,N,N-trimethyl chitosan and polyethyleneimine. The layer-by-layer (LbL) assembly of PEMs was monitored using in situ Fourier-transform surface plasmon resonance (FT-SPR), confirming a stable LbL assembly. X-ray photoelectron spectroscopy (XPS) was used to evaluate surface chemistry, and atomic force microscopy (AFM) was used to determine the surface roughness. The LDH release levels from cells cultured on the Tanfloc-containing PEMs were not statistically different from those on the negative control (p > 0.05), confirming their non-cytotoxicity, while exhibiting remarkable antiadhesive and bactericidal properties against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), respectively. The antibacterial effects were attributed to electrostatic interactions and Tanfloc's polyphenolic nature. This work underscores the potential of Tanfloc as a versatile biomaterial for combating infections on surfaces.

Biomimetic Antibacterial Gelatin Hydrogels with Multifunctional Properties for Biomedical Applications.

A facile novel approach of introducing dopamine and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide via dopamine-triggered in situ synthesis into gelatin hydrogels in the presence of ZnSO4 is presented in this study. Remarkably, the resulting hydrogels showed 99.99 and 100% antibacterial efficiency against Gram-positive and Gram-negative bacteria, respectively, making them the highest performing surfaces in their class. Furthermore, the hydrogels showed adhesive properties, self-healing ability, antifreeze properties, electrical conductivity, fatigue resistance, and mechanical stability from -100 to 80 °C. The added multifunctional performance overcomes several disadvantages of gelatin-based hydrogels such as poor mechanical properties and limited thermostability. Overall, the newly developed hydrogels show significant potential for numerous biomedical applications, such as wearable monitoring sensors and antibacterial coatings.