Effect of side chain variation on surface and biological properties of poly(2-alkyl-2-oxazoline) multilayers

Layer-by-layer assembly of chitosan/alginate thin films containing Salmonella enterica bacteriophages for antibacterial applications

The emergence of antibiotic resistant bacteria and the ineffectiveness of routine treatments inspired development of alternatives to biocides for antibacterial applications. Bacteriophages are natural predators of bacteria and are promising alternatives to antibiotics. This study presents fabrication of a Salmonella enterica bacteriophage containing ultra-thin multilayer film composed of chitosan and alginate and demonstrates its potential as an antibacterial coating for food packaging applications. Chitosan/alginate film was prepared through layer-by-layer (LbL) self-assembly technique. A bacteriophage, which belongs to Siphoviridae morphotype (MET P1-001_43) and infects Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Enteritidis), was post-loaded into chitosan/alginate film. The LbL growth, stability, and surface morphology of chitosan/alginate film as well as phage deposition into multilayers were analysed through ellipsometry, QCM-D and AFM techniques. The bacteriophage containing multilayers showed antibacterial activity at pH 7.0. In contrast, anti-bacterial activity was not observed at acidic conditions. We showed that wrapping a Salmonella Enteritidis contaminated chicken piece with aluminium foil whose surface was modified with phage loaded chitosan/alginate multilayers decreased the number of colonies on the chicken meat, and it was as effective as treating the meat directly with phage solution.

Thiophene α-Chain-End-Functionalized Oligo(2-methyl-2-oxazoline) as Precursor Amphiphilic Macromonomer for Grafted Conjugated Oligomers/Polymers and as a Multifunctional Material with Relevant Properties for Biomedical Applications

Because the combination of π-conjugated polymers with biocompatible synthetic counterparts leads to the development of bio-relevant functional materials, this paper reports a new oligo(2-methyl-2-oxazoline) (OMeOx)-containing thiophene macromonomer, denoted Th-OMeOx. It can be used as a reactive precursor for synthesis of a polymerizable 2,2’-3-OMeOx-substituted bithiophene by Suzuki coupling. Also a grafted polythiophene amphiphile with OMeOx side chains was synthesized by its self-acid-assisted polymerization (SAAP) in bulk. The results showed that Th-OMeOx is not only a reactive intermediate but also a versatile functional material in itself. This is due to the presence of 2-bromo-substituted thiophene and ω-hydroxyl functional end-groups, and due to the multiple functionalities encoded in its structure (photosensitivity, water self-dispersibility, self-assembling capacity). Thus, analysis of its behavior in solvents of different selectivities revealed that Th-OMeOx forms self-assembled structures (micelles or vesicles) by “direct dissolution”.Unexpectedly, by exciting the Th-OMeOx micelles formed in water with λ_abs of the OMeOx repeating units, the intensity of fluorescence emission varied in a concentration-dependent manner.These self-assembled structures showed excitation-dependent luminescence as well. Attributed to the clusteroluminescence phenomenon due to the aggregation and through space interactions of electron-rich groups in non-conjugated, non-aromatic OMeOx, this behavior certifies that polypeptides mimic the character of Th-OMeOx as a non-conventional intrinsic luminescent material.

Recent progress in Tannic Acid-driven antimicrobial/antifouling surface coating strategies

Medical devices and surgical implants are a necessary part of tissue engineering and regenerative medicines. However, the biofouling and microbial colonization on the implant surface continues to be a major...

Thermoresponsive Poly(2-propyl-2-oxazoline) Surfaces of Glass for Nonenzymatic Cell Harvesting

As one of the nonenzymatic cell-harvesting technologies, a thermal-responsive surface based on poly(2-oxazoline)s has achieved initial success in supporting the adhesion and thermal-induced detachment of animal cells. However, because of the laborious preparation procedure, this technique was only limited to research purposes. In this work, through using poly(glycidyl methacrylate) (PGMA) as the anchor layer, poly(2-propyl-2-oxazoline)s (PPOx) were grafted onto glass wafers through a facile two-step coating and annealing procedure for nonenzymatic cell harvesting. In the first step, the piranha solution-activated glass wafers were immersed into the chloroform solution of PGMA and then annealed for a given period of time to immobilize PGMA onto the glass wafers through the bonding between epoxy groups and hydroxyl groups. In the second step, the PGMA-coated glass wafers were further immersed into the chloroform solution of carboxyl-functionalized PPOx. After annealing, PPOx were immobilized onto the PGMA layer through the bonding between carboxyl groups and the residual epoxy groups. Atomic force microscopy, X-ray photoelectron spectroscopy, and ellipsometry were used to characterize the modified glass wafers. The results of cytocompatibility evaluation showed that the PPOx-coated glass wafers were almost nontoxic and were able to support the adhesion and proliferation of L929 cells well. By lowering the temperature to 8 °C, L929 and Vero cells were successfully detached from the PPOx-coated glass wafers without any enzymatic treatment. Further cultivation has demonstrated that the cooling procedure had little effect on cell viability, and the cells still retained good viability after harvesting.