Bio-inspired terpolymers containing dopamine, cations and MPC: a versatile platform to construct a recycle antibacterial and antifouling surface

Mussel-Inspired Polymer-Based Coating Technology for Antifouling and Antibacterial Properties

Zwitterionic coatings provide a promising antifouling strategy against biofouling adhesion. Quaternary ammonium cationic polymers can effectively kill bacteria on the surface, owing to their positive charges. This strategy can avoid the release of toxic biocides, which is highly desirable for constructing coatings for biomedical devices. The present work aims to develop a facile method by covalently grafting zwitterionic and cationic copolymers containing aldehydes to the remaining amine groups of self-polymerized dopamine. Reversible addition-fragmentation chain transfer polymerization was used to copolymerize either zwitterionic 2-methacryloyloxyethyl phosphorylcholine monomer (MPC) or cationic 2-(methacryloyloxy)ethyl trimethylammonium monomer (META) with 4-formyl phenyl methacrylate monomer (FPMA), and the formed copolymers poly(MPC-st-FPMA) and poly(META-st-FPMA) are denoted as MPF and MTF, respectively. MPF and MTF copolymers were then covalently grafted onto the amino groups of polydopamine-coated surfaces. PDA/MPF/MTF-coated surfaces exhibited antibacterial and antifouling properties against S. aureus, E. coli, and bovine serum albumin protein. In addition, they showed excellent viability of normal human lung fibroblast cells MRC-5. We expect the facile surface modification strategy discussed here to be applicable to medical device manufacturing.

Tannic Acid-Based Coatings Containing Zwitterionic Copolymers for Improved Antifouling and Antibacterial Properties

The prevention of biofilm formation on medical devices has become highly challenging in recent years due to its resistance to bactericidal agents and antibiotics, ultimately resulting in chronic infections to medical devices. Therefore, developing inexpensive, biocompatible, and covalently bonded coatings to combat biofilm formation is in high demand. Herein, we report a coating fabricated from tannic acid (TA) as an adhesive and a reducing agent to graft the zwitterionic polymer covalently in a one-step method. Subsequently, silver nanoparticles (AgNPs) are generated in situ to develop a coating with antifouling and antibacterial properties. To enhance the antifouling property and biocompatibility of the coating, the bioinspired zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) was copolymerized with 2-aminoethyl methacrylamide hydrochloride (AEMA) using conventional free-radical polymerization. AEMA moieties containing amino groups were used to facilitate the conjugation of the copolymer with quinone groups on TA through the Michael addition reaction. Three copolymers with different ratios of monomers were synthesized to understand their impacts on fouling resistance: PMPC100, p(MPC80-st-AEMA20), and p(MPC90-st-AEMA10). To impart antibacterial properties to the surface, AgNPs were formed in situ, utilizing the unreacted quinone groups on TA, which can reduce the silver ions. The successful coating of TA and copolymer onto the surfaces was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and its excellent wettability was verified by the water contact angle (CA). Furthermore, the functionalized coatings showed antibacterial properties against E. coli and S. aureus and remarkably decreased the adhesion of the BSA protein. The surfaces can also prevent the adhesion of bacteria cells, as confirmed by the inhibition zone test. In addition, they showed negligible cytotoxicity to normal human lung fibroblast cells (MRC-5). The as-prepared coatings are potentially valuable for biomedical applications.

Nano-Bio Interactions: Biofilm-Targeted Antibacterial Nanomaterials

Biofilm is a spatially organized community formed by the accumulation of both microorganisms and their secretions, leading to persistent and chronic infections because of high resistance toward conventional antibiotics. In view of the tunable physicochemical properties and the related unique biological behavior (e.g., size-, shape-, and surface charge-dependent penetration, protein corona endowed targeting, catalytic- and electronic-related oxidative stress, optical- and magnetic-associated hyperthermia, etc.), nanomaterials-based therapeutics are widely used for the treatment of biofilm-associated infections. In this review, the biological characteristics of biofilm are introduced. And the nanomaterials-based antibacterial strategies are further discussed via biofilm targeting, including preventing biofilm formation, enhancing biofilm penetration, disrupting the mature biofilm, and acting as drug delivery systems. In which, the interactions between biofilm and nanomaterials include mechanical disruption, electron transfer, enzymatic degradation, oxidative stress, and hyperthermia. Additionally, the current advances of nanomaterials for antibacterial nanomaterials by biofilm targeting are summarized. This review aims to present a complete vision of antibacterial nanomaterials-biofilm (nano-bio) interactions, paving the way for the future development and clinical translation of effective antibacterial nanomedicines.

Bactericidal Ability of Well-Controlled Cationic Polymer Brush Surfaces and the Interaction Analysis by Quartz Crystal Microbalance with Dissipation

In this study, cationic poly(2-(methacryloyloxy)ethyl) trimethylammonium chloride) (PMTAC) brush surfaces were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP), and their properties were systematically investigated to discuss the factors affecting their bactericidal properties and interactions with proteins. Model equations for the analysis of electrophoretic behaviors were considered for accurate parameter estimation to indicate the charge density at the interface. The zeta potential dependency of the PMTAC brushes was successfully analyzed using Smolchowski's equation and the Gouy-Chapman model, which describes the diffusive electric double layer. The analysis of the quartz crystal microbalance with dissipation (QCM-D) indicated that the electrostatic interaction promoted protein adsorption, with a large quantity of a negatively charged protein, bovine serum albumin (BSA), being adsorbed. The bactericidal efficiency of the high-graft-density polymer brush (0.45 chains nm-2) was higher than that of the low-graft-density polymer brush (0.06 chains nm-2). To investigate the mechanism of this phenomenon, we applied the dissipation change (ΔD) of QCM-D analysis. The BSA was likewise adsorbed when the brush structure was changed; however, the negative ΔD indicated that the BSA-adsorbed, high-graft-density PMTAC brush became a rigid state. In the bacteria culture media, the behaviors were the same as BSA adsorption, and the high-graft-density polymer brush was also estimated to be more rigid than the low-graft-density polymer brush. Moreover, for S. aureus adhesion after incubating in TSB, a small slope of ΔD/ΔF plots considered initial adsorption of bacteria on the high-graft-density polymer brush strongly interacted compared to that of the low-graft-density polymer brush. The scattered value of the slope of ΔD/ΔF on the high-graft-density polymer brush was considered to be due to the dead bacteria between the bacteria and the polymer brush interface. These investigations for a well-defined cationic polymer brush will contribute to the design of antibacterial surfaces.

Retraction: Construction of a temperature-responsive terpolymer coating with recyclable bactericidal and self-cleaning antimicrobial properties

Retraction of 'Construction of a temperature-responsive terpolymer coating with recyclable bactericidal and self-cleaning antimicrobial properties' by Bailiang Wang et al., Biomater. Sci., 2016, 4, 1731-1741, https://doi.org/10.1039/C6BM00587J.

Polypropylene composite mesh modified by polyurethane gel with ROS scavenging and anti-inflammatory effects for pelvic floor repair

Development of an inflammation modulating polypropylene (PP) mesh in pelvic floor repair is an urgent clinical need. This is because PP mesh for pelvic floor repair can cause a series of complications related to foreign body reactions (FBR) in postoperative period. Therefore, we successfully prepared PP composite mesh that can scavenge reactive oxygen species (ROS) and inhibit inflammation to moderate FBR by a simple method. First, a pregel layer was formed on PP mesh by dip coating. Among them, polyurethane with polythioketal (PTK) is an excellent ROS scavenger, and dopamine methacrylamide (DMA) improves the stability of the coating and synergistically scavenges ROS. Then, a composite mesh (optimal PU50-PP) was obtained by photopolymerization. The results showed that the polyurethane gel layer was able to scavenge more than 90% of free radicals and about 75% of intracellular ROS. In vitro, PU50-PP mesh significantly scavenged ROS and resisted macrophage adhesion. After implantation in the posterior vaginal wall of rats, PU50-PP eliminated 53% of ROS, inhibited inflammation (decreased IL-6, increased IL-10), and dramatically reduced collagen deposition by about 64%, compared to PP mesh. Thus, the composite PP mesh with ROS scavenging and anti-inflammatory properties provides a promising approach for mitigating FBR.

Dopamine-Based Copolymer Bottlebrushes for Functional Adhesives: Synthesis, Characterization, and Applications in Surface Engineering of Antifouling Polyethylene

Nonpolar materials like polyolefins are notoriously challenging substrates for surface modification. However, this challenge is not observed in nature. Barnacle shells and mussels, for example, utilize catechol-based chemistry to fasten themselves onto all kinds of materials, such as boat hulls or plastic waste. Here, a design is proposed, synthesized, and demonstrated for a class of catechol-containing copolymers (terpolymers) for surface functionalization of polyolefins. Dopamine methacrylamide (DOMA), a catechol-containing monomer, is incorporated into a polymer chain together with methyl methacrylate (MMA) and 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM). DOMA serves as adhesion points, BIEM provides functional sites for subsequent "grafting from" reactions, and MMA provides the possibility for concentration and conformation adjustment. First, the adhesive capabilities of DOMA are demonstrated by varying its content in the copolymer. Then, terpolymers are spin-coated on model Si substrates. Subsequently, the atom transfer initiator (ATRP) initiating group is used to graft a poly(methyl methacrylate) (PMMA) layer from the copolymers, with 40% DOMA content providing a coherent PMMA film. To demonstrate functionalization on a polyolefin substrate, the copolymer is spin-coated on high-density polyethylene (HDPE) substrates. A POEGMA layer is grafted from the ATRP initiator sites on the terpolymer chain on the HDPE films to provide antifouling characteristics. Static contact angle values and Fourier transform infrared (FTIR) spectra confirm the presence of POEGMA on the HDPE substrate. Finally, the anticipated antifouling functionality of grafted POEGMA is demonstrated by observing the inhibition of nonspecific adsorption of the fluorescein-modified bovine serum albumin (BSA) protein. The poly(oligoethylene glycol methacrylate) POEGMA layers grafted on 30% DOMA-containing copolymers on HDPE show optimal antifouling performance exhibiting a 95% reduction of BSA fluorescence compared to nonfunctionalized and surface-fouled polyethylene. These results demonstrate the successful utilization of catechol-based materials for functionalizing polyolefin surfaces.

Using Catechol and Zwitterion-Functionalized Copolymers to Prevent Dental Bacterial Adhesion

In this manuscript, we report the synthesis of zwitterionic copolymers and their ability to form antifouling coatings on porous hydroxyapatite as a mimic of dental coatings. Specifically, we systematically investigated how altering the composition of copolymers of catechol methacrylate (Cat-MA or 2) and methacryloyloxyethyl phosphorylcholine (2-MPC) with varying catechol-to-zwitterion ratios impacted their adhesive and antifouling properties, allowing for the rational design of functional coatings. Characterization by ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy revealed the presence of hydrophilic copolymer coatings of ∼10 nm thickness. Notably, these copolymers adhered to hydroxyapatite and reduced the level of attachment of both Gram-negative Escherichia coli and Gram-positive Streptococcus oralis. Additionally, in vitro experiments that mimicked the complex mouth environment (i.e., swallowing and using mouthwash) were employed to evaluate S. oralis adhesion, finding that the copolymer coatings reduced the quantity of adhered bacteria. We suggest that these copolymers provide insights into the design of antifouling coatings that are appropriate for use in oral care.

Synthesis of a novel carboxybetaine copolymer with different spacer lengths and inhibition of nonspecific protein adsorption on its polymer film

Herein, we designed and synthesized a thermally stable carboxybetaine copolymer with a one- or three-carbon spacer between ammonium and carboxylate groups (CBMA1 and CBMA3) to create an anti-nonspecific adsorption surface with the ability to immobilize antibodies. A series of controlled poly(N,N-dimethylaminoethyl methacrylate) was successfully prepared using reversible addition-fragmentation chain-transfer (RAFT) polymerization and was derived to carboxybetaine copolymers of poly(CBMA1-co-CBMA3) [P(CBMA1/CBMA3)] with various CBMA1 contents, including the homopolymers of CBMA1 and CBMA3. Thermal stability of the carboxybetaine (co)polymers was higher than that of the carboxybetaine polymer with a two-carbon spacer (PCBMA2). Further, we also evaluated nonspecific protein adsorption in fetal bovine serum and antibody immobilization on the substrate coated with P(CBMA1/CBMA3) copolymers using surface plasmon resonance (SPR) analysis. As the CBMA1 content increased, nonspecific protein adsorption on the P(CBMA1/CBMA3) copolymer surface decreased. Similarly, the immobilization amount of the antibody decreased as the CBMA1 content increased. However, the figure of merit (FOM), defined as the ratio of the amount of antibody immobilization to that of nonspecific protein adsorption, depended on the CBMA3 content; FOM was higher when the CBMA3 content was 20-40% than those of CBMA1 and CBMA3 homopolymers. These findings will help enhance the sensitivity of the analysis using molecular interaction measurement devices, such as SPR and quartz crystal microbalance.

Polypropylene composite hernia mesh with anti-adhesion layer composed of PVA hydrogel and liposomes drug delivery system

Polypropylene (PP) mesh has been widely used in hernia repair as prosthesis material owing to its excellent balanced biocompatibility and mechanical properties. However, abdominal adhesion between the visceral and PP mesh is still a major problem. Therefore, anti-adhesive PP mesh was designed with poly(vinyl alcohol) (PVA) hydrogel and liposomes drug delivery system. First, PVA hydrogel coating was formed on the surface of PP mesh with freezing-thawing processing cycles (FTP). Subsequently, the lyophilized PVA₁₀-c-PP was immersed in rapamycin (RPM)-loaded liposome solution until swelling equilibrated to obtain the anti-adhesion mesh RPM@LPS/PVA₁₀-c-PP. It was demonstrated that the hydrogel coating can stably fix on the surface of PP mesh even after immersed in PBS solution at 37 °C or 40 °C for up to 30 days. In vitro cell tests revealed the excellent cytocompatibility and the potential to inhibit cell adhesion of the modified PP mesh. Moreover, the anti-adhesive effects of the RPM@LPS/PVA₁₀-c-PP mesh was evaluated through in vivo experiments. The RPM@LPS/PVA₁₀-c-PP mesh exhibited less adhesion than original PP mesh throughout the duration of implantation. At 30 days, the adhesion score of RPM@LPS/PVA₁₀-c-PP mesh was 1.37 ± 0.75, however the original PP was 3 ± 0.71. Furthermore, the results of H&E and Masson trichrome staining proved that the RPM@LPS/PVA₁₀-c-PP mesh showed slighter inflammation response and significant looser fibrous tissue surrounded the PP filaments as compared to the native PP. The current findings manifested that this type of RPM@LPS/PVA₁₀-c-PP might be a potential candidate for anti-adhesion treatment. DATA AVAILABILITY: Data will be made available on request.

Antimicrobial and Antiviral Properties of Triclosan-Containing Polymer Composite: Aging Effects of pH, UV, and Sunlight Exposure

The present study deals with the synthesis and characterization of a polymer composite based on an unsaturated ester loaded with 5 wt.% triclosan, produced by co-mixing on an automated hardware system. The polymer composite's non-porous structure and chemical composition make it an ideal material for surface disinfection and antimicrobial protection. According to the findings, the polymer composite effectively inhibited (100%) the growth of Staphylococcus aureus 6538-P under exposure to physicochemical factors, including pH, UV, and sunlight, over a 2-month period. In addition, the polymer composite demonstrated potent antiviral activity against human influenza virus strain A and the avian coronavirus infectious bronchitis virus (IBV), with infectious activities of 99.99% and 90%, respectively. Thus, the resulting triclosan-loaded polymer composite is revealed to have a high potential as a surface-coating non-porous material with antimicrobial properties.

Mussel-inspired polyurethane coating for bio-surface functionalization to enhance substrate adhesion and cell biocompatibility

Considerable implant materials are prone to cause a severe inflammatory reaction due to poor histocompatibility, which leads to various complications and implant failure. Surface coating modification of these implant materials is one of the most important techniques to settle this problem. However, fabricating a coating with both adequate adhesiveness and excellent biocompatibility remains a challenge. Inspired by the adhesion mechanism of mussels, a series of mussel-inspired polyurethanes (PU-LDAs) were synthysized through a step growth polymerization based on hexamethylene diisocyanate as a hard segment, polytetra-methylene-ether-glycol as a soft segment, lysine-dopamine (LDA) and butanediol as chain extenders with different mole ratios.The coatings of PU-LDAs were applied to various substrates, such as stainless steel, glass and PP using a facile one-step coating process. The introduction of 3,4-dihydroxyphenylalanine (DOPA) groups can greatly improve the adhesion ability of the coatings to the substrates demonstrated by a 180° peel test. The peel strength of the PU-LDA100 coating containing high LDA content was 76.3, 48.5 and 67.5 N/m, which was 106.2%, 246.4% and 192.2% higher than that of the PU-LDA00 coating without LDA on the surface of stainless steel, glass and PP, respectively. Meanwhile, this PU coating has a lower immune inflammatory response which provides a universal method for surface modification of implant materials. Moreover, the DOPA groups in PU-LDAs could combine with the amino and thiol groups on cell membrane surface, leading to the improvement of cell adhesion and growth. Therefore, it has great potential application in the field of biomedical implant materials for the clinic.

Dopamine Assisted Self-Cleaning, Antifouling, and Antibacterial Coating via Dynamic Covalent Interactions

The rapid accumulation of dead bacteria or protein on a bactericidal surface can reduce the effectiveness of the modified surface and alter its biocidal activity by shielding the surface biocide functional groups, promoting microbial attachment and subsequent biofilm formation. Thus, the alteration of biocidal activity due to biofilm formation can cause serious trouble including severe infection or implant or medical device failure leading to death. Therefore, developing a smart self-cleaning surface is of great interest. Ideally, such a surface can not only kill the attached microbials but also release the dead cells and foulants from the surface under a particular incitement on demand. In this project, a sugar-responsive self-cleaning coating has been developed by forming covalent boronic ester bonds between catechol groups from polydopamine and a benzoxaborole pendant from zwitterionic and cationic polymers. To incorporate antifouling properties and enhance the biocompatibility of the coating, bioinspired zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC) was chosen and benzoxaborole pendant containing zwitterionic polymer poly(MPC-st-MAABO) (MAABO: 5-methacrylamido-1,2-benzoxaborole) was synthesized. Additionally to impart antibacterial properties to the surface, a quaternary ammonium containing cationic polymer poly(2-(methacryloyloxy)ethyl trimethylammonium (META)-st-MAABO)) was synthesized. These synthesized polymers were covalently grafted to a polydopamine (PDA) coated surface by forming a strong cyclic boronic ester complex with a catechol group of the PDA layer endowing the surface with bacteria contact-killing properties and capturing specific protein. After the addition of cis-diol containing competitive molecules, i.e., saccharides/sugars, this boronic ester complex with a catechol group of PDA was replaced and the attached polymer layer was cleaved from the surface, resulting in the release of both absorbed protein and live/killed bacteria electrostatically attached to the polymer layer. This dynamic self-cleaning surface can be a promising material for biomedical applications avoiding the gathering of dead cells and debris that are typically encountered on a traditional biocidal surface.

One-step zwitterionization and quaternization of thick PDMAEMA layer grafted through subsurface-initiated ATRP for robust antibiofouling and antibacterial coating on PDMS

In this work, we demonstrate the grafting of thick poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) layer on PDMS via subsurface-initiated atom transfer radical polymerization (SSI-ATRP). The self-migration of DMAEMA monomers into the subsurface of PDMS is proven to be the dominant factor for the success of SSI-ATRP. The as-prepared thick microscale graft layer on PDMS shows much better abrasion resistance than nanoscale graft layer obtained by conventional surface-initiated atom transfer radical polymerization (SI-ATRP) under identical condition. Taking advantage of the tertiary amines of PDMAEMA, the simultaneous zwitterionization and quaternization of the PDMAEMA thick layer is realized through a facile one-step process. The effect of zwitterionization and quaternization degree on the antibiofouling and antibacterial properties is investigated. The results show that a relatively high zwitterionization degree (75 mol%) and a low quaternization degree (25 mol%) exhibit a good well-balanced effect on both fouling repellence and bactericidal activity. This work may lead to the development of robust bifunctional antibiofouling and antibacterial surfaces via SSI-ATRP strategy.

Bioinspired dopamine and zwitterionic polymers for non-fouling surface engineering

Biofouling is a serious problem in the medical, marine, and all other industrial fields as it poses significant health risks and financial losses. Therefore, there is a great demand for endowing surfaces with antifouling properties to mitigate biofouling. Zwitterionic polymers (containing an equimolar number of homogeneously distributed anionic and cationic groups on the polymer chains) have been used extensively as one of the best antifouling materials for surface modification. Being a superhydrophilic polymer, zwitterionic polymers need a strong binding agent to continue to remain attached to the surface for long-term applications. The use of a mussel-inspired dopamine adhesive functional layer is one of the most widely exploited approaches for the attachment of a zwitterion layer on the surface via thiol and amine chemistry. Based on recent studies, we have categorized this dopamine and zwitterion conjugation into four different approaches: (1) conjugation of dopamine with zwitterions by direct modification of zwitterions with the dopamine functional moiety; (2) co-deposition of dopamine with zwitterionic polymers; (3) zwitterionic post modification of the polydopamine (PDA) coated surface; and (4) surface-initiated polymerization of zwitterionic polymers using dopamine modified initiators. In this review, we have briefly discussed about all the possible conjugation mechanisms and reactions for this promising dopamine and zwitterion conjugation and how this conjugated system significantly contributes to the development of non-fouling surfaces along with the other applications.

A Uniform and Robust Bioinspired Zwitterion Coating for Use in Blood-Contacting Catheters with Improved Anti-Inflammatory and Antithrombotic Properties

Inflammation and thrombosis are two major complications of blood-contacting catheters that are used as extracorporeal circuits for hemodialysis and life-support systems. In clinical applications, complications can lead to increased mortality and morbidity rates. In this work, a biomimetic erythrocyte membrane zwitterion coating based on poly(2-methacryloyloxyethyl phosphorylcholine-co-dopamine methacrylate) (pMPCDA) copolymers is uniformly and robustly modified onto a polyvinyl chloride (PVC) catheter via mussel-inspired surface chemistry. The zwitterionic pMPCDA coating exhibits excellent antifouling activity and resists bacterial adhesion, fibrinogen adsorption, and platelet adhesion/activation. The material also demonstrates great hemocompatibility, cytocompatibility, and anticoagulation properties in vitro. Additionally, this biocompatible pMPCDA coating reduces in vivo foreign-body reactions by mitigating inflammatory response and collagen capsule formation, due to its outstanding ability to resist nonspecific protein adsorption. More importantly, when compared with a bare PVC catheter, the pMPCDA coating exhibits outstanding antithrombotic properties when tested in an ex vivo rabbit perfusion model. Thus, it is envisioned that this biomimetic erythrocyte membrane surface strategy will provide a promising way to mitigate inflammation and thrombosis caused by the use of blood-contacting catheters.

A Synthetic Overview of Preparation Protocols of Nonmetallic, Contact-Active Antimicrobial Quaternary Surfaces on Polymer Substrates

Antibacterial surfaces have been researched for more than 30 years and remain highly desirable. In particular, there is an interest in providing antimicrobial properties to commodity plastics, because these, in their native state, are excellent substrates for pathogens to adhere and proliferate on. Therefore, efficient strategies for converting surfaces of commodity plastics into contact-active antimicrobial surfaces are of significant interest. Many systems have been prepared and tested for their efficacy. Here, the synthetic approaches to such active surfaces are reviewed, with the restriction to only include systems with tested antibacterial properties. The review focuses on the synthetic approach to surface functionalization of the most common materials used and tested for biomedical applications, which effectively has limited the study to quaternary materials. For future developments in the field, it is evident that there is a need for development of simple methods that permit scalable production of active surfaces. Furthermore, in terms of efficacy, there is an outstanding concern of a lack of universal antimicrobial action as well as rapid deactivation of the antibacterial effect through surface fouling.

Bioinspired double self-adhesion coating based on dopamine, coating resin and phosphorylcholine for surface lubrication and antifouling functionalization

Implanted medical devices that have poor friction property or biofilm formation can limit their service life and cause discomfort in patients. Recently, some zwitterionic coatings have been studied to modify the biomaterials surface for lubricating function, but the grafting methods of coatings are complicated and also seldom take the bacterial antiadhesion property into account at the same time. In our studies, motivated by the properties of nature mussels and human articular, we firstly successfully synthesized double adhesion protection of self-adhesive ternary polymer coating and achieved the excellent lubrication and antifouling functionalization of the medical devices surface. In details, the X-ray photoelectron spectroscopy, scanning electron microscope and the water contact angles could characterize the successful modification on the surface of titanium substrate. Additionally, the tribological tests carried out by atomic force microscope verified the ternary polymer could enhance the lubrication property owing to the hydration lubrication mechanism. Meanwhile, it also possessed the bacterial antiadhesion property for the initial 24 h attributed to the hydration repulsive force. We believe that, as a simple and universal preparation method, the ternary polymer could make a great significance for improving the surface function of biomaterials and alleviating patients' discomfort.

Increased E. coli bio-adsorption resistance of microfiltration membranes, using a bio-inspired approach

Cells have inherent anti-fouling properties. The mechanisms underpinning these natural properties inform the design of an anti-biosorption coating for a polyethersulfone microfiltration membrane, which includes polydopamine and chitosan layers. This tri-layered membrane is created using quick and easy synthesis method. Its ability to resist bio-adsorption and membrane extracellular polymeric substances (EPS) formation is investigated using the bacterium E. coli (ATCC 11775, 1.5 × 10⁷ CFU/mL). In addition, the proliferative bio-adsorption process is explored on the microfiltration membrane surface, using natural water under static and shaken conditions, while monitoring the bio-adsorption kinetics and EPS dynamic changes. The characterization results show that the modification by polydopamine and chitosan change the membrane surface morphology and increase its hydrophilicity. After 10 min dipping in 5 g/L chitosan solution, the pure water flux of the modified membrane is 5469 ± 30 L/(m²·h) (0.2 bar) and the contact angle decreases to 36.7 ± 1.0°, compared with 9889 ± 23 L/(m²·h) (0.2 bar) and 60.3 ± 1.5° for the unmodified polyethersulfone membrane, respectively. In proliferative bio-adsorption tests, the modified membrane is shown to decrease bio-adsorption by 0.4-2.3 orders of magnitude. However, no antimicrobial function is observed, probably due to the alkaline environment and insufficient functional amino groups. A series of linear and non-linear kinetic models is applied to fit the proliferative bio-adsorption process. The pseudo-second-order model is found to describe the proliferative bio-adsorption process best. Neither total organic carbon (TOC) nor protein is detected on the modified membrane surface. In contrast, on the unmodified PES membrane the ratios of protein/TOC (%), TOC/abundance ((μg/cm²)/CFU (log)) and protein/abundance ((μg/cm²)/CFU(log)) are 10%-16%, 0.17-0.28 and 0.02-0.04, respectively. No significant difference (p > 0.05) is found between static and shaken conditions. All these results point to improved anti-biosorption properties for water treatment applications, encouraging further studies on this membrane.

A mussel-bioinspired multi-functional hyperbranched polymeric coating with integrated antibacterial and antifouling activities for implant interface modification

On the basis of a function integrating strategy, a mussel-inspired hyperbranched polymeric coating with antibacterial and antifouling properties was ingeniously designed and synthesized for the interface modification of implants.

Preparation of Poly(MTZ) n -(DMAEMA) m Micelles and Study on Their Antibacterial Property

Bacterial infections are the most common type of clinical infection. The abuse of clinical antibiotics has led to the frequent appearance of drug-resistant strains and even some super bacteria. In this study, we synthesized Poly(MTZ) _n -(DMAEMA) _m polymer micelles with cations on the surface. The synthesis of this novel polymer comes in two steps. First, Poly(MTZ) _n was synthesized with metronidazole (MTZ) referred as the macromolecular chain transfer agent and v-501 as the initiator for initiating the polymerization of 4-cyanopentanoic acid dithiobenzoate. Then, novel polymer micelles were synthesized with Poly(MTZ) _n referred as the macromolecular chain transfer agent and v-501 as the initiator for initiating the polymerization of the monomer 2-(dimethylamino) ethyl methacrylate, which could adsorb to the negatively charged bacterial surface via electrostatic interaction and enhance bactericidal activity. Scanning electron microscopy showed that the micelles could be accurately targeted to the surface of bacteria, and the zone of inhibition assay confirmed that the micelles could enhance the sensitivity of bacteria to drugs. Hence, Poly(MTZ) _n -(DMAEMA) _m polymer micelles will have potential use for the clinical treatment of anaerobic infections in the future.

Phosphorylcholine- and cation-bearing copolymer coating with superior antibiofilm and antithrombotic properties for blood-contacting devices

The phosphorylcholine- and cation-bering copolymer coating endowed the blood-contacting devices with superior antibiofilm and antithrombotic ability.

Synergistic Chemotherapy and Photodynamic Therapy of Endophthalmitis Mediated by Zeolitic Imidazolate Framework-Based Drug Delivery Systems

Endophthalmitis, derived from the infections of pathogens, is a common complication during the use of ophthalmology-related biomaterials and after ophthalmic surgery. Herein, aiming at efficient photodynamic therapy (PDT) of bacterial infections and biofilm eradication of endophthalmitis, a pH-responsive zeolitic imidazolate framework-8-polyacrylic acid (ZIF-8-PAA) material is constructed for bacterial infection-targeted delivery of ammonium methylbenzene blue (MB), a broad-spectrum photosensitizer antibacterial agent. Polyacrylic acid (PAA) is incorporated into the system to achieve higher pH responsiveness and better drug loading capacity. MB-loaded ZIF-8-PAA nanoparticles are modified with AgNO₃ /dopamine for in situ reduction of AgNO₃ to silver nanoparticles (AgNPs), followed by a secondary modification with vancomycin/NH₂ -polyethylene glycol (Van/NH₂ -PEG), leading to the formation of a composite nanomaterial, ZIF-8-PAA-MB@AgNPs@Van-PEG. Dynamic light scattering, transmission electron microscopy, and UV-vis spectral analysis are used to explore the nanoparticles synthesis, drug loading and release, and related material properties. In terms of biological performance, in vitro antibacterial studies against three kinds of bacteria, i.e., Escherichia coli, Staphylococcus aureus, and methicillin-resistant S. aureus, suggest an obvious superiority of PDT/AgNPs to any single strategy. Both in vitro retinal pigment epithelium cellular biocompatibility experiments and in vivo mice endophthalmitis models verify the biocompatibility and antibacterial function of the composite nanomaterials.

Formation of Hydrophobic Domains on the poly(MPC-co-Dodecyl Methacrylate)-Coated Surface Recognized by Macrophage-like Cells

Copolymers comprising 2-methacryloyloxyethyl phosphorylcholine (MPC) and hydrophobic methacrylic esters were used as biomembrane-mimetic polymers to provide blood compatibility. In the present study, we compared the surfaces coated with two MPC polymers with different alkyl groups, namely, poly(MPC-co-butyl methacrylate) (PMB) and poly(MPC-co-dodecyl methacrylate) (PMD), to clarify the effect of their hydrophobic units. Various substrates, such as poly(ethylene terephthalate), polycarbonate, polypropylene, acrylonitrile-butadiene-styrene copolymer, and stainless steel, were coated with ethanol solutions containing various concentrations of PMD or PMB. The solubility of PMD in ethanol changed depending on the water content. Scanning probe microscopy and rhodamine 6G staining revealed heterogeneous microstructures on the PMD-coated surface but not on the PMB-coated surface. Adhesion of various cells was efficiently suppressed by the PMD coating at lower concentration than the PMB coating, except regarding the adhesion of macrophage-like RAW264.7 cells. Our results suggest that the dodecyl groups in PMD increased its affinity for the substrates and simultaneously induced the formation of hydrophobic domains recognized by RAW264.7 cells.

Pegylated Metal-Phenolic Networks for Antimicrobial and Antifouling Properties

Metal-phenolic networks (MPNs) have recently attracted great interest in material chemistry and biomaterials because of their biocompatible, versatile, and multifunctional properties. In this paper, we describe a facile method for preparation of a designable antifouling, antimicrobial, and substrate-independent coating assembled from the coordination of metal ions and catecholic groups. Hydrophilic and catecholic polymers were synthesized by copolymerization of dopamine methacrylamide (DMA) and poly(ethylene glycol)methyl methacrylate (PEGMA) to afford p(PEGMA- co-DMA). To investigate the assembly and formation of MPN films, two different metal ions, that is, ferrous (Fe^II) and ferric (Fe^III) ions, to react with p(PEGMA- co-DMA) were compared. The binding constants between iron ions and p(PEGMA- co-DMA) have been investigated by ultraviolet-visible spectroscopy (UV-vis). Measurements with atomic force microscopy, contact angle goniometer, and X-ray photoelectron spectroscopy (XPS) were carried out to quantitatively analyze the surface morphology, wettability, and interfacial elemental compositions of coatings, respectively. Moreover, ellipsometric measurements were performed to obtain the film thickness and grafting density. In addition, the pH-responsive property of the MPN films was investigated at different pH values, showing fast disassembly of the networks at low pH. The antifouling properties of the obtained coatings were analyzed by exposing them to bacteria of Escherichia coli and Staphylococcus epidermidis and NIH-3T3 fibroblasts under observation of fluorescence microscopy and cell imaging analysis. The findings suggest that the MPN from complexation of p(PEGMA- co-DMA) and metal ions provides excellent antifouling, pH-responsive, and biocompatible properties on a wide range of substrates. Furthermore, the released iron ions can effectively suppress the growth of bacteria. Accordingly, the new coating architecture offers a universal feature to control surface properties and functionalization for various applications.

Photocurable Urushiol Analogues Bearing Methacryloxy-Containing Side chains

Photocurable urushiol analogues were synthesized using eugenol (an ingredient of clove oil) as the starting material. Photo-induced radical polymerization with 2,2-dimethoxy-2-phenylacetophenone as a photo-initiator took place in the film prepared from the urushiol analogue-bearing methacryloxy groups at the ends of their side chains. Successful polymerization was confirmed by infrared spectroscopy measurements of the film before and after photo-irradiation. Strain-induced elastic buckling instability for mechanical measurement tests revealed that the Young's moduli of the photo-irradiated samples were 4-5 times higher than the films without photo-irradiation. This was attributed to the formation of a highly cross-linked structure through polymerization of the methacrylic moieties and oxidative polymerization of the catechol moieties. Photo-induced surface texturing was also performed for the films prepared on a substrate using a photomask. Negative-tone patterns were successfully obtained after development by soaking in cyclohexanone over several minutes. The preparation of such patterned surfaces was of particular relevance as the obtained surface can serve as a scaffold for cell adhesion, protein immobilization, and the immobilization of other chemicals with spatial disposition.

Rapid Mussel-Inspired Surface Zwitteration for Enhanced Antifouling and Antibacterial Properties

Mussel-inspired dopamine chemistry has increasingly been used for surface modification due to its simplicity, versatility, and strong reactivity for secondary functionalization with amine or thiol containing molecules. In this work, we demonstrate a facile surface modification technique using dopamine chemistry to prepare a zwitterionic polymer coating with both antifouling and antimicrobial property. Catechol containing adhesive monomer dopamine methacrylamide (DMA) was copolymerized with bioinspired zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) monomer, and the synthesized copolymers were covalently grafted onto the amino (-NH₂) rich polyethylenimine (PEI)/polydopamine (PDA) codeposited surface to obtain a stable antifouling surface. The resulting surface was later used for in situ deposition of antimicrobial silver nanoparticles (AgNPs), facilitated by the presence of catechol groups of the coating. The modified surface was characterized using X-ray photoelectron spectroscopy (XPS), water contact angle measurements, and atomic force microscopy (AFM). This dual functional coating significantly reduced the adhesion of both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria and showed excellent resistance to bovine serum albumin (BSA) adsorption. This bioinspired and efficient surface modification strategy with dual functional coating promises its potential application in implantable biomedical devices.

Design of smart targeted and responsive drug delivery systems with enhanced antibacterial properties

The use of antibiotics has been an epoch-making invention in the past few decades for the treatment of infectious diseases. However, the intravenous injection of antibiotics lacking responsiveness and targeting properties has led to low drug utilization and high cytotoxicity. More importantly, it has also caused the development and spread of drug-resistant bacteria due to repeated medication and increased dosage. The differences in the microenvironments of the bacterial infection sites and normal tissues, such as lower pH, high expression of some special enzymes, hydrogen peroxide and released toxins, etc., are usually used for targeted and controlled drug delivery. In addition, bacterial surface charges, antigens and the surface structures of bacterial cell walls are all different from normal tissue cells. Based on the special bacterial infection microenvironments and bacteria surface properties, a series of drug delivery systems has been constructed for highly efficient drug release. This review summarizes the recent progress in targeted and responsive drug delivery systems for enhanced antibacterial properties.

Current and Emerging Approaches to Engineer Antibacterial and Antifouling Electrospun Nanofibers

From ship hulls to bandages, biological fouling is a ubiquitous problem that impacts a wide range of industries and requires complex engineered solutions. Eliciting materials to have antibacterial or antifouling properties describes two main approaches to delay biofouling by killing or repelling bacteria, respectively. In this review article, we discuss how electrospun nanofiber mats are blank canvases that can be tailored to have controlled interactions with biologics, which would improve the design of intelligent conformal coatings or freestanding meshes that deliver targeted antimicrobials or cause bacteria to slip off surfaces. Firstly, we will briefly discuss the established and emerging technologies for addressing biofouling through antibacterial and antifouling surface engineering, and then highlight the recent advances in incorporating these strategies into electrospun nanofibers. These strategies highlight the potential for engineering electrospun nanofibers to solicit specific microbial responses for human health and environmental applications.

pH-sensitive prodrug conjugated polydopamine for NIR-triggered synergistic chemo-photothermal therapy

Combination of chemotherapy with photothermal therapy (PTT) demonstrate highly desirable for efficient medical treatment of tumor. At present works, camptothecin (CPT)-containing polymeric prodrug (PCPT) were fabricated by polymerization of a pH-sensitive camptothecin (CPT) prodrug monomer and MPC using reversible addition-fragmentation transfer (RAFT) strategy. The pH-sensitive polymeric prodrug was tethered onto surface of polydopamine (PDA) nanoparticles by amidation chemistry for combination of chemotherapy with photothermal therapy. Specifically, the active CPT quickly released from the multifunctional nanoparticles in acidic microenvironment ascribe to the cleavage of bifunctional silyl ether linkage. Meanwhile, the PDA could convert the near infrared (NIR) light energy into heat with high efficiency, which makes the resulted nanoparticles an effective platform for photothermal therapy. In vitro analysis confirmed that the PDA@PCPT nanoparticles could be efficiently uptaked by HeLa cells and deliver CPT into the nuclei of cancer cells. The cell viability assays indicated an evident in vitro cytotoxicity to HeLa cancer cells under 808 nm light irradiation. Significant tumor regression was also observed in the tumor-bearing mice model with the combinational therapy provided from the PDA@PCPT nanoparticles. The PDA@PCPT multifunctional system which was achieved by a facile route should be a potential candidate in the anti-cancer field due to the synergistic therapeutic effect, which is superior to any single approach.

Synthesis of chitosan-based micelles for pH responsive drug release and antibacterial application

The over- and inefficient release of antibiotics from common delivery systems causes the development of drug-resistant bacteria. In the present work, methoxy poly(ethylene glycol)-poly(ε-caprolactone)-chitosan/montmorillonite (MPC/MMT) hybrid multilayer films were constructed for bacterial infections and pH-dependent release of the hydrophobic drug triclosan (TCA). The thickness of the (MPC-T/MMT)₁₀ multilayer films was 384.4 ± 26.5 nm, and the TCA loading dosage was 2.4 μg/cm². Staphylococcus aureus, Escherichia coli and Staphylococcus epidermidis were used in the antibacterial tests. pH responsive TCA release from the prepared multilayer films was examined by measuring the bactericidal activity of the films after immersion in PBS (pH 7.4) or MES (pH 5.5) and zone of inhibition on nutrient agar. In vitro bacterial shake-flask, zone of inhibition and live/dead staining results demonstrated the high sterilization efficiency of the films. Furthermore, cell biocompatibility measurements toward L929 fibroblasts and human lens epithelial cells showed no adverse effects of the multilayer film.

Mechanisms underlying interactions between PAMAM dendron-grafted surfaces with DPPC membranes

Biofouling is a pervasive problem which demands the creation of smart, antifouling surfaces. Towards this end, we examine the interactions between a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer and a polyamidoamine (PAMAM) dendron-grafted surface. In addition, we investigate the impact of dendron generation on the system behavior. To resolve the multiscale dynamical processes occurring over a large spatial scale, we employ Molecular Dynamics simulations with a coarse-grained implicit solvent force field. Our results demonstrate the transient and equilibrium system dynamics to be determined by the PAMAM dendron generation along with the underlying mechanisms. Higher generation dendrons are observed to favor penetration of the DPPC molecules into the dendron branches, thereby enabling sustained interactions between the membrane and the dendron-grafted surface. Under equilibrium, the membrane adopts a bowl-shaped morphology whose dimensions are determined by the dendron generation and density of interactions. The results from our study can be used to guide the design of novel surfaces with selective antifouling properties which can prevent the adsorption of microorganisms onto lipid membranes.

The interactions between a DPPC lipid membrane and a PAMAM dendron-grafted surface.

Bacterial self-defense antibiotics release from organic-inorganic hybrid multilayer films for long-term anti-adhesion and biofilm inhibition properties

Implant-associated bacterial infections pose serious medical and financial issues due to the colonization and proliferation of pathogens on the surface of the implant. The as-prepared traditional antibacterial surfaces can neither resist bacterial adhesion nor inhibit the development of biofilm over the long term. Herein, novel (montmorillonite/poly-l-lysine-gentamicin sulfate)8 ((MMT/PLL-GS)8) organic-inorganic hybrid multilayer films were developed to combine enzymatic degradation PLL for on-demand self-defense antibiotics release. Small molecule GS was loaded into the multilayer films during self-assembly and the multilayer films showed pH-dependent and linear growth behavior. The chymotrypsin- (CMS) and bacterial infections-responsive film degradation led to the peeling of the films and GS release. Enzyme-responsive GS release exhibited CMS concentration dependence as measured by the size of the inhibition zone and SEM images. Notably, the obtained antibacterial films showed highly efficient bactericidal activity which killed more than 99.9% of S. aureus in 12 h. Even after 3 d of incubation in S. aureus, E. coli or S. epidermidis solutions, the multilayer films exhibited inhibition zones of more than 1.5 mm in size. Both in vitro and in vivo antibacterial tests indicated good cell compatibility, and anti-inflammatory, and long-term bacterial anti-adhesion and biofilm inhibition properties.

Bacterial infection microenvironment-responsive enzymatically degradable multilayer films for multifunctional antibacterial properties

The adhesion of bacteria is one of the most important stages in biofilm formation and bacterial infection. Once bacteria have adhered to a biomaterial surface, it is hard to eliminate them, and bacterial growth and infection are inevitable. In the current study, we have designed and constructed enzymatically degradable (hyaluronic acid/chitosan)n-(hyaluronic acid/polylysine)n ((HA/CHI)n-(HA/PLL)n) composite multilayer films via a layer-by-layer self-assembly method. Spectroscopic ellipsometry and scanning electron microscopy cross section measurements showed the exponential growth behavior of (HA/CHI)10-(HA/PLL)10 multilayer films (∼2 μm). The increased secretion of hyaluronidase and chymotrypsin in the bacterial infection microenvironment led to the fast degradation of the outer (PLL/HA)n multilayer films in the first 24 h. Enzymatic degradation of the multilayer films efficiently reduced the adhesion of both Staphylococcus aureus and Escherichia coli (>99%). Bacterial live/dead staining demonstrated the bactericidal action of the remaining bottom (CHI/HA)n multilayer films against the two kinds of bacteria. In vivo subcutaneous tests on New Zealand white rabbits, wound appearance and histopathology analysis showed that the implantation of composite multilayer film-modified PDMS promoted wound healing and the materials demonstrated a self-defense antibacterial effect. The material demonstrated both anti-adhesive and bactericidal properties and could be used to modify biomedical implants.

Self-Assembled Polyprodrug Amphiphile for Subcutaneous Xenograft Tumor Inhibition with Prolonged Acting Time In Vivo

Polymeric drug delivery system termed as "polyprodrug amphiphile" poly(2-methylacryloyloxyethyl phosphorylcholine)-b-poly(10-hydroxy-camptothecin methacrylate (pMPC-b-pHCPT) is developed for the prolonged-acting cancer therapy. It is obtained by two-step reversible addition-fragmentation chain transfer polymerization of zwitterionic monomer MPC and an esterase-responsive polymerizable prodrug methacrylic anhydride-CPT, respectively. This diblock polymer is composed of both antifouling (pMPC) and bioactive (pHCPT) segments and the drug is designed as a building block to construct the polymer skeleton directly. Due to its distinct amphiphilicity, the polymer can self-assemble into micelles with different dynamic sizes by facilely tuning the ratio of MPC/HCPT under physiological conditions. The outer pMPC shell is superhydrophilic to form dense hydrate layer preventing the nanosystem from unwanted nonspecific protein adsorption, which is the main lead cause of the rapid clearance of nanoparticles in vivo, thus facilitating the accumulation of drugs in tumor sites via enhanced permeability and retention effect. The configuration of the polyprodrug amphiphile is confirmed by several measurements. The resistance to albumin adsorption, prolonged plasma retention time, accumulation in tumor sites, and anticancer activity of the micelles is also investigated in vitro and in vivo. This novel amphiphile can be expected as a promising agent for the passive targeted prolonged-acting cancer therapy.

Probing the neutralization behavior of zwitterionic monomer-containing dental adhesive

OBJECTIVE

To investigate the polymerization kinetics, neutralization behavior, and mechanical properties of amine-functionalized dental adhesive cured in the presence of zwitterionic monomer, methacryloyloxyethyl phosphorylcholine (MPC).

METHODS

The control adhesive was a mixture based on HEMA/BisGMA/2-N-morpholinoethyl methacrylate (MEMA) (40/30/30, w/w/w). The control and experimental formulations containing MPC were characterized with regard to water miscibility of liquid resins, photopolymerization kinetics, water sorption and solubility, dynamic mechanical properties and leachables from the polymers (aged in ethanol). The neutralization behavior of the adhesives was determined by monitoring the pH of lactic acid (LA) solution.

RESULTS

The water miscibility decreased with increasing MPC amount. The water sorption of experimental copolymer specimen was greater than the control. The addition of 8wt% water led to improved photo-polymerization efficiency for experimental formulations at MPC of 2.5 and 5wt%, and significant reduction in the cumulative amounts of leached HEMA, BisGMA, and MEMA, i.e. 90, 60 and 50% reduction, respectively. The neutralization rate of MPC-containing adhesive was faster than control. The optimal MPC concentration in the formulations was 5wt%.

SIGNIFICANCE

Incompatibility between MEMA and MPC led to a decrease in water miscibility of the liquid resins. Water (at 8wt%) in the MPC-containing formulations (2.5-5wt% MPC) led to higher DC, faster RPmax and significant reduction in leached HEMA, BisGMA, and MEMA. The neutralization rate was enhanced with the addition of MPC in the amine-containing formulation. Promoting the neutralization capability of dentin adhesives could play an important role in reducing recurrent decay at the composite/tooth interface.

Biocompatible magnetite nanoparticles synthesized by one-pot reaction with a cell membrane mimetic copolymer

In this paper, a series of random copolymers poly(methacrylic acid -co-2-methacryloyloxyethyl phosphorylcholine) P(MAA-co-MPC) were synthesized firstly via RAFT living polymerization. The P(MAA-co-MPC) copolymer side chains bear cell membrane phosphorylcholine zwitterions to endow biocompatibility and carboxylic groups to confer coordination with metal ions. Thus, the copolymer was adopted to modify Fe₃O₄ nanoparticle by a one-pot coprecipitation approach. The effects of the copolymer composition as well as the ratio between the copolymers and iron ions on the performances of the magnetite nanoparticles were researched. The diameters of the nanoparticles could be easily tuned by changing the initial copolymer amount. Moreover, a long-term colloidal stability of magnetite particles was obtained after P(MAA-co-MPC) modification. Biocompatibility of the P(MAA-co-MPC) copolymer coated magnetite nanoparticles was investigated by protein adsorption, in vitro cytotoxicity and cell uptake studies. It was found that the copolymer content of magnetite nanoparticles correlates with its biocompatibility. Excellent biocompatibility could be obtained when the content of the copolymer in the composite nanoparticles reached to 54%.

A self-defensive antibacterial coating acting through the bacteria-triggered release of a hydrophobic antibiotic from layer-by-layer films

Drug delivery systems play important roles in the construction of antibacterial coatings on the surfaces of biomaterials. However, excessive release of antibiotics in the environment can lead to the generation of resistant bacteria. A methoxy poly(ethylene glycol)-poly(ε-caprolactone)-chitosan (MPEG-PCL-CS) block polymer was prepared through covalent grafting of CS onto MPEG-PCL. MPEG-PCL-CS micelles were prepared and showed a high load capacity for the hydrophobic antibiotic triclosan (TCA) (∼5 wt%). Multilayer films were constructed through self-assembling TCA/MPEG-PCL-CS cationic micelles with poly(acrylic acid) (PAA). Transmission and scanning electron microscopy analyses confirmed the presence of micelles on the surface (20-40 nm). As barriers for the antibiotic, the (TCA/MPEG-PCL-CS)/PAA multilayer films contained a high load of TCA (255 μg cm-2). Importantly, the multilayer films showed both bacteria-triggered and pH-responsive release properties and can be used as self-defensive antibacterial coatings. Bacterial adhesion caused a local acidic environment and altered the permeability of the multilayer films, promoting drug release. Both in vitro and in vivo antibacterial tests indicated a high bactericidal activity of drug-loaded multilayer films against both E. coli and S. aureus.

Cationic Acrylate Oligomers Comprising Amino Acid Mimic Moieties Demonstrate Improved Antibacterial Killing Efficiency

Cu(0)-mediated polymerization was employed to synthesize a library of structurally varied cationic polymers and their application as antibacterial peptide mimics was assessed. Eight platform polymers were first synthesized with low degrees of polymerization (DP) using (2-Boc-amino)ethyl acrylate as the monomer and either ethyl α-bromoisobutyrate or dodecyl 2-bromoisobutyrate as the initiator (thus providing hydrocarbon chain termini of C2 or C12, respectively). A two-step modification strategy was then employed to generate the final sixteen-member polymer library. Specifically, an initial deprotection was employed to reveal the primary amine cationic polymers, followed by guanylation. The biocidal activity of these cationic polymers was assessed against various strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pneumoniae. Polymers having a short segment of guanidine units and a C12 hydrophobic terminus were shown to provide the broadest antimicrobial activity against the panel of isolates studied, with MIC values approaching those for Gram-positive targeting antibacterial peptides: daptomycin and vancomycin. The C12-terminated guanidine functional polymers were assayed against human red blood cells, and a concomitant increase in haemolysis was observed with decreasing DP. Cytotoxicity was tested against HEK293 and HepG2 cells, with the lowest DP C12-terminated polymer exhibiting minimal toxicity over the concentrations examined, except at the highest concentration. Membrane disruption was identified as the most probable mechanism of bacteria cell killing, as elucidated by membrane permeability testing against E. coli.

Poly(dopamine)-inspired surface functionalization of polypropylene tissue mesh for prevention of intra-peritoneal adhesion formation

The poly(dopamine)-inspired coating of O₂ plasma treated PP mesh with chitosan shows an excellent anti-adhesion property.