Chitosan-Based Peptidopolysaccharides as Cationic Antimicrobial Agents and Antibacterial Coatings.

The rapid spread of multidrug-resistant bacteria has called for effective antimicrobial agents which work on a more direct mechanism of killing. Cationic peptidopolysaccharides are developed in the present work to mimic the peptidoglycan structure of bacteria and to enhance the membrane-compromising bactericidal efficacy. Antimicrobial CysHHC10 peptide was grafted to the C-2 (amino) or C-6 (hydroxyl) position of chitosan backbone via thiol-maleimide "click" conjugation, utilizing the maleimidohexanoic linkers. The peptidopolysaccharide with primary amino backbone intact (CSOHHC) exhibited higher bactericidal activity toward Gram-positive and Gram-negative bacteria, in comparison to that with amino backbone grafted with the peptide (CSNHHC). Both peptidopolysaccharides also exhibited lower hemolytic activity and cytotoxicity than free CysHHC10 peptide due to the moderation effect contributed by the chitosan backbone. For targeting the Gram-positive bacteria in particular, the CSOHHC expressed 4- and 2-fold increases in hemo- and cytoselectivity, respectively, as compared to the CysHHC10 peptide. In an extended application, peptidopolysaccharide antibacterial coatings were formed via layer-by-layer assembly with tannic acid. The peptidopolysaccharide coatings readily killed the adhered bacteria upon contact while being cytocompatible by maintaining more than 60% viability for the adhered fibroblasts. Therefore, the peptidoglycan-mimetic peptidopolysaccharides are potential candidates for anti-infective drugs in biomedical applications.

Extending the Arc of Rotation of the Pectoralis Major Myocutaneous Flap for Orofacial Reconstruction via a Modified Subclavicular Route Through the Clavipectoral Fascia.

PURPOSE: Drawbacks of the conventional supraclavicular overlay of the pectoralis major myocutaneous flap (PMMF) include the resultant unesthetic cervical bulge and the limited cephalad extension that limits its use to mandibular or cervical defects. This study discusses the technique and comparative advantages of a more esthetic subclavicular route through the clavipectoral fascia that allows an increased arc of rotation to reconstruct orofacial defects. MATERIALS AND METHODS: Patients with orofacial defects that were reconstructed with a PMMF through the modified subclavicular route were included in this retrospective cohort study, which aimed to compare the gain in extension accorded through the modified subclavicular tunnel over an initial conventional supraclavicular overlay. Outcome variables included the dimension of each skin paddle and the cross-sectional area of each flap. Other variables, such as age and gender, also were investigated. Complications that arose from this technique were statistically compared with these variables and with those from previously reported studies. All data analyses were performed using Pearson χ2 and correlation tests. RESULTS: Twelve patients (7 women and 5 men) who underwent a primary reconstruction with the PMMF during a 1-year period from November 2010 to November 2011 were selected for this study. All 12 flaps survived; 3 developed minor postoperative complications that resolved within the 3-month review period. A PMMF with an average dimension of 12.75 × 6.0 × 3.725 cm and cross-sectional area of 20.65 cm2 could pass through this modified tunnel, achieving an average gain in extension of 3.2 cm that enabled the reconstruction of defects up to and above the level of the oral commissure. Apart from skin paddle dimension, all other variables were not found to be statistically related to the extension accorded by the modified route. Complications that occurred appeared to be related only to the cross-sectional area of the flap. CONCLUSION: The increased cephalad extension afforded by this modified subclavicular route through the clavipectoral fascia permitted the reconstruction of orofacial defects that would otherwise have required free vascularized grafts with microvascular surgery and avoided the unesthetic cervical bulge from conventional supraclavicular overlays of the PMMF.

Conjugation of Polyphosphoester and Antimicrobial Peptide for Enhanced Bactericidal Activity and Biocompatibility.

Enhancing the bactericidal activity and moderating the toxicity are two important challenges in the design of upcoming antimicrobial compounds. Herein, antimicrobial macromolecules were developed by conjugating CysHHC10 peptide and polyphosphoester for the modulation of microbiocidal activity and biocompatibility. The conjugation was carried out via thiol-yne "click" chemistry between the cysteine terminal of the peptide and the pendant propargyl moieties of the polyphosphoester. The bactericidal efficacy of the polyphosphoester-peptide conjugates were investigated by microbial growth inhibition toward the Gram-positive and Gram-negative bacteria. On the basis of peptide mass fraction, the polyphosphoester-peptide conjugates exhibited lower values of minimum inhibitory concentration than that of the free peptide. The polyphosphoester-peptide conjugates also exhibited ultralow hemolytic characteristic at a concentration of 4000 µg/mL, indicating significant improvement of erythrocytes compatibility as compared to the free peptide that readily caused lysis of 50% of red blood cells at 1000 µg/mL. Cytotoxicity of the polyphosphoester-peptide conjugates toward 3T3 fibroblast cells was also reduced in comparison to that of the free peptide. Conjugation of the polyphosphoester thus improves the bactericidal efficacy and biocompatibility of the antimicrobial peptide.

Tea stains-inspired initiator primer for surface grafting of antifouling and antimicrobial polymer brush coatings.

Inspired by tea stains, plant polyphenolic tannic acid (TA) was beneficially employed as the primer anchor for functional polymer brushes. The brominated TA (TABr) initiator primer was synthesized by partial modification of TA with alkyl bromide functionalities. TABr with trihydroxyphenyl moieties can readily anchor on a wide range of substrates, including metal, metal oxide, polymer, glass, and silicon. Concomitantly, the alkyl bromide terminals serve as initiation sites for atom transfer radical polymerization (ATRP). Cationic [2-(methacryloyloxy)ethyl]trimethylammonium chloride (META) and zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) and N-(3-sulfopropyl)-N-(methacryloxyethyl)-N,N-dimethylammonium betaine (SBMA) were graft-polymerized from the TABr-anchored stainless steel (SS) surface. The cationic polymer brushes on the modified surfaces are bactericidal, while the zwitterionic coatings exhibit resistance against bacterial adhesion. In addition, microalgal attachment (microfouling) and barnacle cyprid settlement (macrofouling) on the functional polymer-grafted surfaces were significantly reduced, in comparison to the pristine SS surface. Thus, the bifunctional TABr initiator primer provides a unique surface anchor for the preparation of functional polymer brushes for inhibiting both microfouling and macrofouling.

Phytic Acid-Promoted Deposition of Gold Nanoparticles with Grafted Cationic Polymer Brushes for the Construction of Synergistic Contact-Killing and Photothermal Bactericidal Coatings.

Medical implants are constantly facing the risk of bacterial infections, especially infections caused by multidrug resistant bacteria. To mitigate this problem, gold nanoparticles with alkyl bromide moieties (Au NPs-Br) on the surfaces were prepared. Xenon light irradiation triggered the plasmon effect of Au NPs-Br to induce free radical graft polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA), leading to the formation of poly(DMAEMA) brush-grafted Au NPs (Au NPs-g-PDM). The Au NPs-g-PDM nanocomposites were conjugated with phytic acid (PA) via electrostatic interaction and van der Waals interaction. The as-formed aggregates were deposited on the titanium (Ti) substrates to form the PA/Au NPs-g-PDM (PAP) hybrid coatings through surface adherence of PA and the gravitational effect. Synergistic bactericidal effects of contact-killing caused by the cationic PDM brushes, and local heating generated by the Au NPs under near-infrared irradiation, conferred strong antibacterial effects on the PAP-deposited Ti (Ti-PAP) substrates. The synergistic bactericidal effects reduced the threshold temperature required for the photothermal sterilization, which in turn minimized the secondary damage to the implant site. The Ti-PAP substrates exhibited 97.34% and 99.97% antibacterial and antiadhesive efficacy, respectively, against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), compared to the control under in vitro antimicrobial assays. Furthermore, the as-constructed Ti-PAP surface exhibited a 99.42% reduction in the inoculated S. aureus under in vivo assays. In addition, the PAP coatings exhibited good biocompatibility in the hemolysis and cytotoxicity assays as well as in the subcutaneous implantation of rats.

Reactive graphene oxide nanosheets: a versatile platform for the fabrication of graphene oxide-biomolecule/polymer nanohybrids.

Graphene oxide (GO) nanosheets can be functionalized with reactive pentafluorophenyl ester via esterification of the carboxylic groups. The resulting reactive GO nanosheets provide a versatile platform for grafting of amino-containing polymers or biomolecules via ester-amine coupling. Coupling of poly[(9,9-dioctylfluorene)-alt-(4-amino-phenylcarbazole)] (PFCz-NH(2) ), amino-terminated hyperbranched polyglycerol (HPG-NH(2) ), and lysozyme (Lyz) was illustrated. The Al/GO-g-PFCz/ITO sandwich thin-film device exhibits bistable electrical switching and rewritable memory effects. The GO-g-Lyz nanohybrids exhibit high bactericidal efficacy against S. aureus and E. coli, while the GO-g-HPG nanohybrids exhibit reduced cytotoxicity toward 3T3 fibroblasts.

Surface modification of silicone for biomedical applications requiring long-term antibacterial, antifouling, and hemocompatible properties.

Silicone has been used for peritoneal dialysis (PD) catheters for several decades. However, bacteria, platelets, proteins, and other biomolecules tend to adhere to its hydrophobic surface, which may lead to PD outflow failure, serious infection, or even death. In this work, a cross-linked poly(poly(ethylene glycol) dimethacrylate) (P(PEGDMA)) polymer layer was covalently grafted on medical-grade silicone surface to improve its antibacterial and antifouling properties. The P(PEGDMA)-grafted silicone (Silicone-g-P(PEGDMA)) substrate reduced the adhesion of Staphylococcus aureus , Escherichia coli , and Staphylococcus epidermidis , as well as 3T3 fibroblast cells by ≥90%. The antibacterial and antifouling properties were preserved after the modified substrate was aged for 30 days in phosphate buffer saline. Further immobilization of a polysulfobetaine polymer, poly((2-(methacryloyloxy)ethyl)dimethyl-(3-sulfopropyl)ammonium hydroxide) (P(DMAPS)), on the Silicone-g-P(PEGDMA) substrate via thiol-ene click reaction leads to enhanced antifouling efficacy and improved hemocompatibility with the preservation of the antibacterial property. Compared to pristine silicone, the so-obtained Silicone-g-P(PEGDMA)-P(DMAPS) substrate reduced the absorption of bovine serum albumin and bovine plasma fibrinogen by ≥80%. It also reduced the number of adherent platelets by ≥90% and significantly prolonged plasma recalcification time. The results indicate that surface grafting with P(PEGDMA) and P(DMAPS) can be potentially useful for the modification of silicone-based PD catheters for long-term applications.

Preparation of fluorescent organometallic porphyrin complex nanogels of controlled molecular structure via reverse-emulsion click chemistry.

Here, we are the first to report a novel approach to preparing well-defined poly(ethylene glycol) (PEG) fluorescent nanogels, with well-defined molecular structures and desired functionalities via reverse (mini)emulsion copper(I)-catalyzed azide-alkyne cycloaddition (REM-CuAAC). Nanogels with hydroxyl groups and Ga-porphyrin complex (Ga-porphyrin-OH nanogels), as well as with Ga-porphyrin complex and folate functional groups (Ga-porphyrin-FA), are successfully prepared. Nanogels of 30 and 120 nm in diameter are obtained and they exhibit an emission maxima within the wavelength range 700-800 nm. The nanogels could find uses in near infrared (NIR) imaging attributable to their fluorescence and their functionality for cell affinity.

Intradermal administration of green synthesized nanosilver (NS) through film-coated PEGDA microneedles for potential antibacterial applications.

Skin infections caused by pathogens, including bacteria, fungi and viruses, are difficult to completely eliminate through standard topical administration, owing to the restricted drug permeation into the epidermis layer. Herein, we developed a poly(ethylene glycol) diacrylate (PEGDA) microneedle patch with surface coating of a nanosilver (NS) encapsulated gelatin/sucrose film for antibacterial applications, by virtue of enhanced skin permeation by microneedle penetration and efficient drug delivery through rapid film dissolving. NS was facilely synthesized through a green process based on the bioinspired crystallization of ionic state silver in the presence of a silk fibroin (SF) template. A gelatin/sucrose polymeric film encapsulating NS was dressed on the surface of the mold cavity, and film-coated PEGDA (PEGDA/film-NS) microneedles were subsequently fabricated through standard ultraviolet (UV) light-induced polymerization. To demonstrate their advantages for therapeutic applications, the physicochemical properties of the as-developed microneedles were characterized in terms of their morphology, composition, mechanical strength, etc. Moreover, rapid NS release from PEGDA@film-NS microneedles driven by the aqueous environment was demonstrated under physiological conditions. Additionally, such film-coated microneedles exhibited good mechanical strength for skin penetration, and their antibacterial activity against Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus) as well as Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was verified using bacterial suspension in vitro. Altogether, such a minimally invasive strategy exhibited good potential for realizing a broad-spectrum antibacterial effect, which may provide a practical methodology for the management of polymicrobial skin infection during clinical trials.

Simultaneous deposition of tannic acid and poly(ethylene glycol) to construct the antifouling polymeric coating on Titanium surface.

Titanium (Ti) and its alloys are primarily explored to produce biomedical implants owing to their improved mechanical stability, corrosion resistance, low density, and good biocompatibility. Despite, Ti substrate surfaces are easily contaminated by plasma proteins and bacteria. Herein, a simple one-step process for the simultaneous deposition of a polyphenol tannic acid (TA) and four-armed poly(ethylene glycol) (PEG10k-4-OH) on the Ti substrate (Ti-TA/PEG) surface was described. Additionally, a two-step process has been employed to fabricate the Ti-TA-PEG surface via successive deposition of TA and PEG10k-4-OH for comparison. The resultant Ti-TA/PEG surface prepared by simultaneous deposition of TA and PEG10k-4-OH exhibits higher coating thickness and better surface coverage than the Ti-TA-PEG surface. The Ti-TA/PEG and Ti-TA-PEG surfaces could actively inhibit the non-specific adsorption of proteins, suppress the bacterial and platelet adhesion, and prevents biofilm formation. Moreover, the Ti-TA/PEG surface displays a better antifouling performance than the Ti-TA-PEG surface. Thus, the present study demonstrates a simple and convenient approach for constructing polymeric coating with good anti-adhesive properties on the Ti substrate surface.

Mussel Adhesive Mimetic Silk Sericin Prepared by Enzymatic Oxidation for the Construction of Antibacterial Coatings.

With the rapid development and advancement in orthodontic and orthopedic technologies, the demand for biomedical-grade titanium (Ti) alloys is growing. The Ti-based implants are susceptible to bacterial infections, leading to poor healing and osteointegration, resulting in implant failure or repeated surgical intervention. Silk sericin (SS) is hydrophilic, biocompatible, and biodegradable and could induce a low immunological response in vivo. As a result, it would be intriguing to investigate the use of hydrophilic SS in surface modification. In this work, the tyrosine moiety in SS was oxidized by tyrosinase (or polyphenol oxidase) to the 3,4-dihydroxyphenylalanine (DOPA) form, generating the catechol moiety-containing SS (SSC). Inspired by the adhesion of mussel foot proteins, the SSC coatings could be directly deposited onto multiple surfaces in SS and tyrosinase mixed stock solutions to create active surfaces with catechol groups. Further, the SSC-coated Ti surfaces were hybridized with silver nanoparticles (Ag NPs) via in situ silver ion (Ag+) reduction. The antibacterial properties of the Ag NPs/SS-coated Ti surfaces are demonstrated, and they can prevent bacterial cell adhesion as well as early-stage biofilm formation. In addition, the developed Ag NPs/SSC-coated Ti surfaces exhibited a negligible level of cytotoxicity in L929 mouse fibroblast cells.

Amino-containing tannic acid derivative-mediated universal coatings for multifunctional surface modification.

The development of a universal coating strategy for the construction of functional surfaces and modulation of surface properties is of great research interest. Tannic acid (TA) could serve as a sole precursor for the deposition of colorless coatings on substrate surfaces. However, the deposition of TA requires a high salt concentration (0.6 M), which may limit its practical application. Herein, primary amine moieties were introduced on the gallic acid groups in TA. The resultant amine-containing TA derivative (TAA) can self-polymerize under mild conditions (10 mM, Tris buffer), and form uniform and colorless coatings in a material-independent manner. In comparison with the TA coating under the same preparation conditions, the TAA coating exhibits an increased thickness as measured by ellipsometry. The TAA coating is adapted for secondary surface functionalization. The hydrophilic mPEG brushes can be grafted on the TAA coating to inhibit non-specific protein adsorption. A biotin probe can be immobilized on the TAA coating to promote specific binding with avidin. In addition, the TAA coating can be utilized for in situ reduction of silver ions to AgNPs. The resulting AgNP-loaded TAA coating can inhibit bacterial adhesion and prevent biofilm formation.

Hydrothermal derived protoporphyrin IX nanoparticles for inactivation and imaging of bacteria strains.

Overuse and abuse of antibiotics greatly hasten the development of microbial drug resistance and substantially threat to global public health. Developing alternative methods for combating bacterial infections is urgently required. In this work, a simple hydrothermal approach was employed to prepare the protoporphyrin IX-polyethylenimine nanoparticles (PPIX-PEI NPs) containing abundant amine groups and PPIX moieties. The as-obtained PPIX-PEI NPs exhibit antibacterial properties against both Gram-positive and Gram-negative bacteria. The presence of PPIX in the PPIX-PEI NPs can generate reactive oxygen species (ROS) under 635 nm laser irradiation, which enhance the antibacterial properties of the PPIX-PEI NPs against Gram-positive bacteria. Thus, the PPIX-PEI NPs display a synergistic antibacterial activity against Gram-positive bacteria in the combination of antibacterial photodynamic therapy (PDT). In addition, emission of red fluorescence by the PPIX-PEI NPs can help to differentiate bacteria and observe the bacterial morphologies using a confocal laser scanning microscope (CLSM).

Deposition of catechol-functionalized chitosan and silver nanoparticles on biomedical titanium surfaces for antibacterial application.

The titanium (Ti) and its alloys have been widely used for dental and orthopedic implants. However, the Ti-based implants may suffer from bacterial infection, which would result in insufficient healing, implant failure and repeated surgical intervention. It is of great interest to inhibit the bacterial adhesion and colonization on the Ti-based implants by introducing proper surface coatings. In this work, a simple method was employed to synthesize the water-soluble catechol-containing chitosan (CACS). The CACS coatings can be deposited onto various substrate surfaces and exhibit substrate-independent behavior. The CACS-coated Ti surfaces were further deposited with silver nanoparticles (Ag NPs) via in-situ reduction of Ag+ ions using catechol moieties as the reducing agents. The resulting AgNPs/CACS-coated Ti surfaces exhibit antibacterial properties and can prevent the surface adhesion of bacterial cells, as evidenced by the inhibition zone test, live/dead bacterial staining assay and spread plate method. In addition, they show negligible cytotoxicity to L929 mouse fibroblast cells.

Modified maxillary reconstruction technique for Brown's class III defects by subdividing a rhomboid shaped iliac crest into 2 subunits.

BACKGROUND: Men and women share a common maxillary morphology with heterogeneity in size. This indicated that our technique of reconstruction with a rhomboid-shaped iliac crest bone flap incorporating a 30° vertical wedge osteotomy may be widely used for Brown's class III maxillectomy defect reconstruction among a population with class I skeletal profile. The reconstruction of Brown's class III maxillary defects is extremely challenging. The purpose of this study was to closely study the maxilla geometrically in order to establish a standardized maneuver, which facilitates conversion of the iliac bone flap into a natural maxilla's contours. METHODS: We evaluated the geometries of 40 adult maxillas. The perimeter lengths of perinasal and infraorbital subunits were analyzed, in addition to the intersecting angle (δ) of both subunits. Sex variation was evaluated using the Student's t test. RESULTS: In the 80 studied unilateral maxillas (40 maxillas from 18 men and 22 women), there were no significant sex differences for δ (P = .1527). In addition, both sexes shared common morphological features, hence, in surgical reconstruction, the δ can be constantly set at 150°. Perimeter of bone segments had a greater intersubject variability (coefficient of variation [CV] of approximately 4.5-11). From both cadaveric dissections and clinical applications, our results have shown that our standard maneuver was reproducible and reliable in reestablishing natural facial contours. CONCLUSION: Our standard maneuver can serve as a universal guideline, with individualized perimeter manipulations, to yield an aesthetically natural and functional outcome.

Preparation of Plasma Membrane Vesicles from Bone Marrow Mesenchymal Stem Cells for Potential Cytoplasm Replacement Therapy.

We have previously reported on the generation of plasma membrane vesicles (PMVs) through the mechanical extrusion of mammalian cells. The fusion of PMVs with mitochondrial deficient Rho0 cells restored mitotic activity under normal culture conditions. Atherosclerosis, type 2 diabetes, Alzheimer's disease, and cancer are age-related diseases that have been reported to be associated with multiple mechanical and functional defects in the cytosol and organelles of a variety of cell types. Bone marrow mesenchymal stem cells (BMSCs) represent a unique cell population from the bone marrow that possess self-renewal capabilities while maintaining their multipotency. The supplementation of senescence cells with young cytoplasm from autologous BMSCs via the fusion of PMVs provides a promising approach to ameliorate or even reverse age-associated phenotypes. This protocol describes how to prepare PMVs from BMSCs via extrusion through a polycarbonate membrane with 3 µm pores, determine the existence of mitochondria and examine the maintenance of membrane potential within PMVs using a confocal microscope, concentrate PMVs by centrifugation, and carry out the in vivo injection of PMVs into the gastrocnemius muscle of mice.

Preventing Early-Stage Graft Bone Resorption by Simultaneous Innervation: Innervated Iliac Bone Flap for Mandibular Reconstruction.

BACKGROUND: Postoperative resorption of vascularized bone grafts jeopardizes the success of dental implant(s) and functional rehabilitation of the jaw. Recent evidence supports the crucial role of innervation in bone regeneration and turnover. METHODS: This study reports a new technique for simultaneous innervation of vascularized iliac flaps in mandibular reconstruction, through neurorrhaphy between ilioinguinal nerves, which innervate iliac bone, and inferior alveolar nerves or great auricular nerves. Twenty-two patients (aged 50 to 69 years) with postoncologic continuity defects of the mandible underwent mandibular reconstruction (10 innervated flaps and 12 control flaps). Graft bone resorption was analyzed by computed tomographic scans at 6 and 12 months postoperatively, and bone quality was evaluated for dental implantation, with histologic and histomorphometric analyses for graft samples. RESULTS: At 12-month follow-up, graft bone density loss in the control group was significantly higher than in the innervated group (p < 0.05). Bone quality evaluation indicated a suitable condition for dental implantation in all patients in the innervated group but in 41.7 percent of patients in the control group. Histologic and histomorphometric analyses showed successful innervation in the innervated group but not in the control group. Osteoclast activity was significantly higher in the control group than in the innervated group (p < 0.05). CONCLUSIONS: Innervated iliac flaps may effectively prevent bone resorption of grafts in mandible reconstruction that otherwise jeopardize the success of dental implants. This new strategy of innervation of bone flaps appears clinically valuable and provides insights into the homeostasis of grafts for functional reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

A modified technique for reconstruction of a total maxillary defect.

Total maxillary defects with orbital retention (Brown class 2b) are a challenge to reconstructive surgeons because of the variety of anatomical structures involved. Traditional techniques to reconstruct the orbital floor, zygoma, and maxilla using only a vascularised fibular flap are complicated, as the osteotomy and orientation of bone are difficult. Reconstruction of the orbital floor with titanium mesh may also cause palpable discomfort and increase the risk of secondary infection. We describe a modified technique using a vascularised fibular flap, together with a coronoid temporalis pedicle flap, which we used in two patients in whom we achieved satisfactory aesthetic and functional results. Our technique provides adequate tissue for infraorbital skin defects, provides pedicles of sufficient length, and requires only one fibular osteotomy. To our knowledge this is the first report of this technique.

Antifouling coatings based on covalently cross-linked agarose film via thermal azide-alkyne cycloaddition.

Coatings based on thin films of agarose-poly(ethylene glycol) (Agr-PEG) cross-linked systems are developed as environmentally-friendly and fouling-resistant marine coatings. The Agr-PEG cross-linked systems were prepared via thermal azide-alkyne cycloaddition (AAC) using azido-functionalized Agr (AgrAz) and activated alkynyl-containing poly(2-propiolamidoethyl methacrylate-co-poly(ethylene glycol)methyl ether methacrylate) P(PEMA-co-PEGMEMA) random copolymers as the precursors. The Agr-PEG cross-linked systems were further deposited onto a SS surface, pre-functionalized with an alkynyl-containing biomimetic anchor, dopamine propiolamide, to form a thin film after thermal treatment. The thin film-coated SS surfaces can effectively reduce the adhesion of marine algae and the settlement of barnacle cyprids. Upon covalent cross-linking, the covalently cross-linked Agr-PEG films coated SS surfaces exhibit good stability in flowing artificial seawater, and enhanced resistance to the settlement of barnacle cyprids, in comparison to that of the surfaces coated with physically cross-linked AgrAz films.

PEG-based hydrogels prepared by catalyst-free thiol-yne addition and their post-antibacterial modification.

PEG-based hydrogels possess tissue-like mechanical elasticity, solute permeability, cytocompatibility and biocompatibility. In this work, PEG-based hydrogels were prepared via nucleophilic thiol-yne addition between a 4-arm PEG functionalized with thiols (PEG10k-4-SH) and an electron-deficient alkyne (PEG10k-4-PP). The as-fabricated hydrogels still possess residual functionalities, enabling a second nucleophilic thiol-yne addition on the gel matrix. A thiol-containing fluorescent dye was conjugated with the electron-deficient alkyne appended hydrogels. A thiol-containing antimicrobial peptide (AMP-SH) was also embedded into the gel matrix via nucleophilic thiol-yne addition. The inhibition of bacterial growth in suspensions and contaminated substrate surfaces by the AMP-embedded hydrogels was studied. The cytotoxicity of unmodified and AMP-embedded PEG-based hydrogels against 3T3 fibroblasts was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) viability assay.