Construction of gelatin/alginate hydrogels doped hemicyanine derivatives for photodynamic antibacterial application.

Hydrogel systems based on natural polymer materials have provided alternative opportunities for preparing antimicrobial dressings. A composite antibacterial hydrogel system containing gelatin (Gel), alginate (Alg) and hemicyanine derivatives with different chain lengths (C3, C6 and C10) was constructed. The composite hydrogels have excellent swelling ability and low degradability due to the classical three-dimensional network structure. Because of the photosensitization ability of C3, C6 and C10, hydrogels containing these molecules can also effectively produce reactive oxygen species (ROS) under light. Importantly, the hydrogel containing C3 molecules that have higher spatial extension structure and shorter alkyl chain than C6 and C10 shows better photo-responsive antibacterial effect against drug-resistant Escherichia coli. The bacterial killing activity of the composite hydrogel system could be regulated by changing the alkyl chain length of the photosensitizers. This effective and photo-responsive composite hydrogel system is expected to be used for bacteria-infected wound repair and promoting wound healing.

Halogen atom regulation of acceptor-donor-acceptor type conjugated molecules for photothermal antibacterial and antibiofilm therapy.

Drug-resistant bacteria and biofilm have caused serious public health problems. It is necessary to develop a treatment that is highly effective against drug-resistant bacteria without inducing drug resistance. Herein, we prepare a series of nanoparticles based on three conjugated molecules (BTP-BrCl, BTP-ClBr, and BTP-ClmBr) with acceptor-donor-acceptor (A-D-A) structure. By adjusting the position of the halogen atoms, the photothermal properties can be effectively regulated. In particular, these three nanoparticles (BTP-BrCl, BTP-ClBr, and BTP-ClmBr NPs) exhibited photothermal conversion efficiencies (PCE) up to 57.4%, 60.3%, and 75.9%, respectively. Among these nanoparticles, BTP-ClmBr NPs with the chlorine atom close to the carbonyl and the bromine atom away from the carbonyl in the acceptor have the highest PCE. Due to their excellent photothermal properties, all the NPs achieved more than 99.9% antibacterial activity against AmprE. coli, S. aureus and MRSA. When S. aureus was treated with these three nanoparticles under light irradiation, little biofilm formation was observed. Moreover, they could kill more than 99.9% of the bacteria in the biofilm. In summary, this study provides a strategy for the preparation of high-performance nano-photothermal agents and their application in the field of anti-drug resistant bacteria and biofilm prevention and cure.

High-throughput fluorescence sensing array based on tetraphenylethylene derivatives for detecting and distinguishing pathogenic microbes.

Infections induced by pathogenic microorganisms will bring negative effects such as diseases that damage health and result in heavy economic burden. Therefore, it is very important to detect and identify the pathogens in time. Moreover, traditional clinical diagnosis or food testing often faces the problem of dealing with a large number of samples. Here, we designed a high-throughput fluorescent sensor array based on the different binding ability of five tetraphenylethylene derivatives (TPEs) with various side chains to different kinds of pathogenic microbes, which is used to detect and distinguish various species, so as to realize rapid mass diagnosis, and hopefully provide guidance for further determination of microbial infections and clinical treatment.