Institute of Integrative Biosciences, CECOS University of IT and emerging sciences, Peshawar 25000, Pakistan.
Department of Environmental Sciences, Abdul Wali Khan University, Mardan, Pakistan.
J Photochem Photobiol B. 2019 Mar;192:141-146. doi: 10.1016/j.jphotobiol.2019.01.021. Epub 2019 Jan 31.
Multidrug resistance (MDR) in bacteria is a major concern these days. One of the reasons is the mutation in efflux pump that prevents the retention of antibiotics and drugs in the bacterial cell. The current work is a step to overcome MDR in bacteria via inhibition of efflux pump and further photoinhibition by thiolated chitosan coated cobalt doped zinc oxide nanoparticles (Co-ZnO) in visible light. Co-ZnO were synthesized in a size range of 40-60 nm. Antibacterial activity of the Co-ZnO against methicillin resistant Staphylococcus aureus (MRSA) was found 100% at a concentration of 10 μg/ml upon activation in sunlight for 15 min. Interestingly, it was found that cobalt as a dopant was able to increase the photodynamic and photothermal activity of Co-ZnO, as in dark conditions, there was only 3-5% of inhibition at 10 μg/ml of nanoparticle concentration. Upon excitation in light, these nanoparticles were able to generate reactive oxygen species (ROS) with a quantum yield of 0.23 ± 0.034. The nanoparticles were also generating heat, Because of the magnetic nature, thus helping in more killing. Thiolated chitosan further helped in blocking the efflux pump of MRSA. The current nanoparticles were also found biocompatible on human red blood cells (LD = 214 μg/ml). These data suggest that the MRSA killing ability was facilitated through efflux inhibition and oxidative stress upon excitation in visible light hence, were in accordance with previous findings.
目前，细菌的多药耐药性（MDR）是一个主要关注点。其中一个原因是外排泵的突变，这使得抗生素和药物无法在细菌细胞内保留。目前的工作是通过抑制外排泵并进一步用光还原硫代壳聚糖包覆的钴掺杂氧化锌纳米粒子（Co-ZnO）在可见光下进行光抑制来克服细菌的 MDR。Co-ZnO 的尺寸范围在 40-60nm 之间。Co-ZnO 对耐甲氧西林金黄色葡萄球菌（MRSA）的抗菌活性在 10μg/ml 的浓度下经阳光激活 15 分钟后达到 100%。有趣的是，研究发现钴作为掺杂剂能够提高 Co-ZnO 的光动力和光热活性，因为在黑暗条件下，在 10μg/ml 的纳米粒子浓度下仅抑制了 3-5%。在光照下激发时，这些纳米粒子能够产生具有 0.23±0.034 量子产率的活性氧物质（ROS）。由于磁性性质，纳米粒子还会产生热量，从而有助于更多的杀灭。巯基化壳聚糖进一步有助于阻断 MRSA 的外排泵。当前的纳米粒子在人红细胞上也表现出良好的生物相容性（LD=214μg/ml）。这些数据表明，MRSA 的杀伤能力是通过在可见光激发下的外排抑制和氧化应激来促进的，这与之前的发现是一致的。
