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 (PEG-4-SH) and an electron-deficient alkyne (PEG-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.
Poly(dopamine acrylamide)-grafted poly(vinylidene fluoride) (PVDF-g-PDA) microfiltration (MF) membranes were fabricated via (i) thermally-induced radical graft copolymerization of pentafluorophenyl acrylate from ozone-pretreated PVDF, (ii) reactive ester-amine reaction with dopamine hydrochloride, and (iii) membrane casting via phase inversion. The resulting catecholcontaining PVDF-g-PDA MF membranes can be further functionalized via spontaneous reduction and chelating of Ag and Au nanoparticles on the surface, and via grafting of thiol-terminated poly(ethylene glycol) (PEG-SH), amino-terminated poly(N-isopropylacrylamide) (PNIPAM-NH 2 ) or amino-terminated hyperbranched polyglycerol (HPG-NH 2 ) in Michael addition or Schiff base reactions. The as-synthesized PVDF-g-PDA/Ag nanoparticles composite MF membrane was explored for its antibacterial efficacy against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). The resulting PVDF-g-PDA/Au nanoparticles composite MF membrane was investigated as the catalytic support for the reduction of 4-hydroxynitrobenzene. The obtained PVDF-g-PDA/PNIPAM, PVDF-g-PDA/ PEG and PVDF-g-PDA/HPG MF membranes exhibit thermo-responsive, biocompatible and anti-fouling properties, respectively.
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 (Agrg-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.
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