Suppressing persistent multidrug-resistant (MDR) bacterial infections and excessive inflammation is the key for treating chronic wounds. Therefore, developing a microenvironment-responsive material with good biodegradability, drug-loading, anti-infection, and anti-inflammatory properties is desired to boost the chronic wounds healing process; however, using ordinary assembly remains a defect. Herein, we propose a pH/enzyme dual-responsive polymyxin B (PMB) spatiotemporal-release hydrogel (GelMA/OSSA/PMB), namely, the amount of OSSA and PMB released from GelMA/OSSA/PMB was closely related the wound pH and the enzyme concentration changing. The GelMA/OSSA/PMB showed better biosafety than equivalent free PMB, owing to the controlled release of PMB, which helped kill planktonic bacteria and inhibit biofilm activity in vitro. In addition, the GelMA/OSSA/PMB exhibited excellent antibacterial and anti-inflammatory properties. A MDR Pseudomonas aeruginosa caused infection was effectively resolved by the GelMA/OSSA/PMB hydrogel in vivo, thereby significantly boosting wound closure during the inflammatory phase. Furthermore, GelMA/OSSA/PMB accelerated the sequential phases of wound repair.
Han Ying,Yang Xinyao,Jia Yuhao,Liu Mingying,Sun Xinglin,Yu Dan,Zhang Dayi
Salmonella is a Gram-negative bacterium causing intestinal infections. Polymyxin B (PMB) is an effective antibiotic against Salmonella , but the emergence of antibiotic resistance poses a growing concern. To address this challenge, this study synthesized a new nanocarrier by functionalizing nano-montmorillonite (NMMT) with PMB by adsorption, namely NMMT@PMB. PMB adsorption on NMMT followed the Langmuir isotherm and pseudo‑first‑order kinetics, and its release kinetics followed a diffusion-controlled mechanism. Although the minimum inhibitory concentration (MIC) of NMMT@PMB (2.78 and 44.54 µg/mL) was slightly higher than that of free PMB (2 and 32 µg/mL) for PMB-sensitive (S AT ) and resistant (S AT−P ) Salmonella typhimurium , the nanocarrier demonstrated sustained long‑term antibacterial activity over time. The antibacterial mechanism was the disruption of bacterial membrane integrity. Additionally, ex vivo results demonstrated that NMMT@PMB regulated the microbial community composition, increasing the relative abundance of probiotic bacteria (from 72.34% to 75.20%) and inhibiting pathogenic bacteria (from 8.54% to 2.36%), thereby facilitating its return toward the original state. These findings suggest that NMMT@PMB is a promising nano-delivery system that may support sustained antibacterial action and microbiota homeostasis, offering a potential strategy for improved management of Salmonella infections.
Li Zhang,Yiwen Zhao,Yuwei Wu,Yanping Jiang,Qianwei Wang,Xinyi Lin,Gang Song,Kunlun Huang,Zhiyi Yao
Antibiotic residue in food products has aroused considerable public concerns all over the world. It is of great significance to develop an efficient approach for rapid detection of antibiotics in food. In this work, a selective and sensitive method for detecting Polymyxins B (PMB) was established in 100 % aqueous media based on the supramolecular aggregates of water-soluble perylene diimide (PDI) derivative. We have designed and synthesized a series of PDI derivatives (PDI-1, 2, 3, 4, Scheme 1). The sensing performance and mechanism of PDI-based probes werestudied by absorption, emission, and circular dichroism (CD) techniques. It was found that the formation of the supramolecular aggregate driven by the non-covalent interactions between PMB and PDIs accounted for the fluorescence quenching of PDIs. PDI-1 was screened to be the most effective probe, which has the characteristics of detecting PMB rapidly and intuitively in both solution state and solid support. The detection limit can be extended to be 18.5 nmol/L by the aid of fluorometry. PDI-1 can also be used for the determination of PMB in practical samples with high sensitivity and large operative range. To the best of our knowledge, this work is the first example of fluorescent sensing PMB based on organic molecular probes in 100 % aqueous media.
危险品化学品经营许可证（带存储）