Hydrogels have been considered as promising materials in tissue engineering and biomedical areas. However, the weak and brittle nature of common synthetic hydrogels largely hinders their potential applications. Therefore, it is challenging to fabricate tough hydrogels for biomedical applications. In this manuscript, well-defined and thermo-responsive polyurethane-poly(ethylene glycol) (PU-PEG) hydrogels were prepared via thermally-induced copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition (CuAAC) using azido-pendent PU-PEG and dialkynyl PEG as the gel precursors. The physical properties of the as-formed hydrogels were investigated by swelling ratios and mechanical tests. The PU-PEG hydrogels not only possess thermo-responsive and excellent mechanical properties, but also exhibit good biocompatibility.

Bacterial infections can cause serious health problems. The rapid identification of bacteria plays a vital role in the treatment of bacterial infection at an early stage of the disease. In this work, an active polythiophene derivative containing reactive pentafluorophenyl (PFP) ester pendant groups was prepared via Fe3+-catalyzed oxidative polymerization. As far as we know, this is the first report of active polythiophene with reactive PFP ester moieties. The active polythiophene derivative was conjugated with vancomycin and α-methoxy-ω-amino poly(ethylene glycol) (mPEG-NH2) via a reactive ester–amine reaction, resulting in the formation of water-soluble and fluorescent vancomycin-containing polythiophene (PTPVan). Since vancomycin can selectively interact with Gram-positive bacteria and kill them, the antibacterial properties of PTPVan were evaluated. The detection of Gram-positive bacteria was carried out by observing the color change and the fluorescence response of bacteria upon incubation with PTPVan through the naked eye and a fluorescence spectroscope, respectively. The staining of Gram-positive bacteria was observed using a confocal laser scanning microscope (CLSM).

A fluorescence technique to investigate the interactions between bacterial membranes and an aggregation-induced emission (AIE) luminogen-decorated AMP (TPE-AMP) was reported. Our simple and fast method consists of mixing TPE-AMP and bacterial suspensions and recording the fluorescence signals by flow cytometry and confocal microscopy in a “non-washing” manner.

A biomimetic strategy was developed for the construction of antifouling titanium oxide (Ti(oxide)) surfaces based on host-guest interactions. Two catecholic derivatives, dopamine 4-(phenylazo)benzamide (AZODopa) and dopamine 1-adamantanecarboxamide (AdaDopa) were synthesized and immobilized onto the Ti(oxide) surfaces. The guest molecules-anchored Ti(oxide) surfaces were further functionalized with zwitterionic heptakis[6-deoxy-6-(N-3-sulfopropyl-N,N-dimethylammonium ethyl sulfanyl)]-β-cyclodextrin (SBCD) and hydrophilic β-CD polymer (CDP). The surface elemental compositions and hydrophobic/hydrophilic properties of the Ti(oxide) surfaces before and after modification were characterized by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements, respectively. The antifouling properties of the modified Ti(oxide) surfaces were evaluated by the protein adsorption and bacterial adhesion assays. The zwitterionic SBCD- and hydrophilic CDP-functionalized Ti(oxide) surfaces can reduce the adsorption of bovine plasma fibrinogen and adhesion of Escherichia coli, as compared to the pristine and guest molecules-anchored Ti(oxide) surfaces.The fabrication of antifouling coatings via biomimetic anchoring and host-guest interactions was developed.Two new catecholic guest molecules were syntehsized.A new zwitterionic β-cyclodextrin was prepared.The adhesion of bacteria and adsorption of proteins on the coatings were reduced.

Polymeric quaternary ammonium salts (QAS) have been widely studied for their antimicrobial activities. However, most of them were evaluated and used in solution form, which may limit their other applications, in medical and wound care and surface biofouling prevention. The development of antibacterial agents for use both in solution and in surface biofouling prevention are highly interesting and desirable. In this work, quaternized poly(2-(dimethylamino)ethyl methacrylate)-grafted agarose (Agr-g-QPDMAEMA) copolymers were synthesized via a combination of atom transfer radical polymerization (ATRP) and quaternization of tertiary amine moieties. The resulting Agr-g-QPDMAEMA copolymers can be dissolved in aqueous media at low concentrations to evaluate their antibacterial activity in the solution form. They can also be gelated as hydrogels on substrate surfaces to inhibit bacterial adhesion, biofilm formation and bacterial colonization. The Agr-g-QPDMAEMA copolymer hydrogels can be further fabricated into antibacterial patches to inhibit the bacteria growth on the contaminated surfaces.

•Hierarchical N-succinyl chitosan and sodium alginate hybrid film was fabricated.•The film exhibited high tensile strength, light transmittance and stability.•Rare earth coordination bonding was utilized to cross-link the NSC-SA hybrid films.Nacre-like hybrid films based on N-succinyl chitosan (NSC), sodium alginate (SA) and lanthanide ions were fabricated via coordination interactions. In this work, the binary building blocks (NSC and SA) were self-assembled into aligned hydrogel films by coordination with lanthanide ions, and hierarchical NSC-SA hybrid films were obtained upon drying. Two species of lanthanide ions (Gd3+ and Yb3+) were used to fabricate the hierarchical NSC-SA hybrid films. The as-prepared NSC-SA hybrid films exhibit high tensile strength and stability. The tensile strength and toughness of as-prepared hybrid films reach 122.10 MPa and 3.89 MJ m−3, respectively. Meanwhile, the well-aligned lamellar microstructures also exhibit a good light transmittance. The highest light transmittance reaches 92% for NSC-SA hybrid films at 760 nm. This fabrication method for hierarchical NSC-SA hybrid films is innovative due to the utilization of rare earth coordination bonding, and can serve as the basic strategy for the construction of high-performance composites in the near future.

A fluorescence technique to investigate the interactions between bacterial membranes and an aggregation-induced emission (AIE) luminogen-decorated AMP (TPE-AMP) was reported. Our simple and fast method consists of mixing TPE-AMP and bacterial suspensions and recording the fluorescence signals by flow cytometry and confocal microscopy in a “non-washing” manner.

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.