Citronellol-Based Long-Lasting Antibacterial Cotton Fabrics without Bacterial Resistance

Self-Assembled Borneol-Guanidine-Based Amphiphilic Polymers as an Efficient Antibiofilm Agent

Biofilm-associated infections remain a tremendous obstacle to the treatment of microbial infections globally. However, the poor penetrability to a dense extracellular polymeric substance matrix of traditional antibacterial agents limits their antibiofilm activity. Here, we show that nanoaggregates formed by self-assembly of amphiphilic borneol-guanidine-based cationic polymers (BGNx-n) possess strong antibacterial activity and can eliminate mature Staphylococcus aureus (S. aureus) biofilms. The introduction of the guanidine moiety improves the hydrophilicity and membrane penetrability of BGNx-n. The self-assembled nanoaggregates with highly localized positive charges are expected to enhance their interaction with negatively charged bacteria and biofilms. Furthermore, nanoaggregates dissociate on the surface of biofilms into smaller BGNx-n polymers, which enhances their ability to penetrate biofilms. BGNx-n nanoaggregates that exhibit superior antibacterial activity have the minimum inhibitory concentration (MIC) of 62.5 μg·mL-1 against S. aureus and eradicate mature biofilms at 4 × MIC with negligible hemolysis. Taken together, this size-variable self-assembly system offers a promising strategy for the development of effective antibiofilm agents.

Long-Lasting Antibacterial PDMS Surfaces Constructed from Photocuring of End-Functionalized Polymers

A challenge remains in the development of anti-infectious coatings for the inert surfaces of biomedical devices that are prone to bacterial colonization and biofilm formation. Here, a facile photocuring method to construct functionalized polymeric coatings on inert polydimethylsiloxane (PDMS) surfaces, is developed. Using atom transfer radical polymerization (ATRP) initiator bearing thymol group, hydrophilic DMAEMA and benzophenone (BP)-containing monomers are copolymerized to form polymers with end functional groups. An end-functionalized biocidal coating is then constructed on the inert PDMS surface in one step using a photocuring reaction. The functionalized PDMS surfaces show excellent antibacterial and antifouling properties, are capable of completely eradiating MRSA within ≈6 h, and effectively inhibit the growth of biofilms. In addition, they have good stability and long-lasting antibacterial activity in body fluid environments such as 0.9% saline and urine. According to bladder model experiments, the catheter's lifespan can be extended from ≈7 to 35 days by inhibiting the growth and migration of bacteria along its inner surface. The photocuring technique is therefore very promising in terms of surface functionalization of inert biomedical devices in order to minimize the spread of infection.

Antibacterial effect of ultrasound and β-citronellol against Listeria monocytogenes and its application in carrot preservation

This study investigated the antibacterial effects of ultrasound (US), β-citronellol (CT), and a combination of the two treatments on Listeria monocytogenes. Results showed that US or CT alone did not show apparent antibacterial effect (0.02-0.76 log CFU/mL reduction). The combined treatment showed obviously inactivate effect of L. monocytogenes, the populations of L. monocytogenes decreased by 8.93 log CFU/mL after US (253 W/cm2, 20 kHz) + 0.8 mg/mL CT treatment. US + CT treatment also had a significant (P < 0.05) antibacterial effect on isolates of L. monocytogenes from three different serotypes. In this study, the damage of US + CT on cell morphology had been observed using field emission scanning electron microscopy, while the damage to cell membranes by US + CT was observed by confocal laser scanning microscopy and flow cytometry. Meanwhile, the uptake of N-phenyl-l-naphthylamine and the absorbance at 260 and 280 nm also indicated that the combined treatment disrupted the permeability and integrity of L. monocytogenes membranes. Reactive oxygen species and malondialdehyde assays showed that US + CT exacerbated cellular oxidative stress and lipid peroxidation. In addition, the US + CT treatment reduced L. monocytogenes by 3.14-4.24 log CFU/g on the surface of carrots. Total phenolic and carotenoid contents in carrots were elevated after US + CT treatment. During storage, compared to control, US + CT did not significantly (P > 0.05) change the surface color of carrots but significantly (P < 0.05) decreased both hardness and weight, and has an impact on the sensory. This study showed that US + CT is a promising cleaning method that will provide new ideas for the preservation of fresh agricultural produce.