Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, UNLP, CCT La Plata, CONICET, CC16 Suc 4 (1900), La Plata, Argentina.
ACS Appl Mater Interfaces. 2013 Apr 24;5(8):3149-59. doi: 10.1021/am400044e. Epub 2013 Apr 12.
A common problem with implants is that bacteria can form biofilms on their surfaces, which can lead to infection and, eventually, to implant rejection. An interesting strategy to inhibit bacterial colonization is the immobilization of silver (Ag) species on the surface of the devices. The aim of this paper is to investigate the action of citrate-capped silver nanoparticles (AgNPs) on clinically relevant Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria in two different situations: (i) dispersed AgNPs (to assess the effect of AgNPs against planktonic bacteria) and (ii) adsorbed AgNPs on titanium (Ti) substrates, a material widely used for implants (to test their effect against sessile bacteria). In both cases, the number of surviving cells was quantified. The small amount of Ag on the surface of Ti has an antimicrobial effect similar to that of pure Ag surfaces. We have also investigated the capability of AgNPs to kill planktonic bacteria and their cytotoxic effect on UMR-106 osteoblastic cells. The minimum bactericidal concentration found for both strains is much lower than the AgNP concentration that leads to cytotoxicity to osteoblasts. Planktonic P. aeruginosa show a higher susceptibility to Ag than S. aureus, which can be caused by the different wall structures, while for sessile bacteria, similar results are obtained for both strains. This can be explained by the presence of extracellular polymeric substances in the early stages of P. aeruginosa biofilm formation. Our findings can be important to improving the performance of Ti-based implants because a good bactericidal action is obtained with very small quantities of Ag, which are not detrimental to the cells involved in the osseointegration process.
植入物的一个常见问题是，细菌可以在其表面形成生物膜，这可能导致感染，并最终导致植入物被排斥。一种抑制细菌定植的有趣策略是将银（Ag）物种固定在设备表面。本文的目的是研究柠檬酸封端的银纳米粒子（AgNPs）在两种不同情况下对临床相关革兰氏阳性（金黄色葡萄球菌）和革兰氏阴性（铜绿假单胞菌）细菌的作用：（i）分散的 AgNPs（评估 AgNPs 对浮游细菌的作用）和（ii）吸附在钛（Ti）基底上的 AgNPs，Ti 是一种广泛用于植入物的材料（测试其对固定细菌的作用）。在这两种情况下，都定量了存活细胞的数量。Ti 表面上少量的 Ag 具有类似于纯 Ag 表面的抗菌作用。我们还研究了 AgNPs 杀死浮游细菌的能力及其对 UMR-106 成骨细胞的细胞毒性。两种菌株的最低杀菌浓度都远低于导致成骨细胞细胞毒性的 AgNP 浓度。与金黄色葡萄球菌相比，浮游铜绿假单胞菌对 Ag 的敏感性更高，这可能是由于细胞壁结构不同所致，而对于固定细菌，两种菌株的结果相似。这可以用铜绿假单胞菌生物膜形成的早期阶段存在细胞外聚合物来解释。我们的研究结果对于提高基于 Ti 的植入物的性能可能很重要，因为只需少量 Ag 即可获得良好的杀菌作用，而这对参与骨整合过程的细胞没有不利影响。
