Collaborative Research: The Antimicrobial Properties of Silver Nanoparticles: mechanisnms and water chemistry effects

纳米银是目前市场上超过20%的纳米产品的有效成分，是商业应用中最常用的纳米材料。大约88%的这些产品具有某种形式的抗菌或抗菌活性。银纳米颗粒表现出不同于离子和块状材料的物理性质。由于其强大的抗菌特性，一些研究表明，银纳米颗粒在生物医学和环境应用方面具有潜在的用途，例如伤口和烧伤的治疗以及水的消毒。虽然银纳米颗粒的抗菌特性已被广泛证实，但它们在细菌、病毒和原生动物灭活中的消毒机制和动力学尚未被阐明。事实上，目前还没有研究测试银纳米颗粒灭活小隐孢子虫和贾第鞭毛虫等原生动物病原体的能力。以往的研究并未涉及环境条件对纳米银抗菌性能的影响。研究人员假设，银纳米粒子的抗菌过程可能有三种：(1)银粒子与细胞膜直接相互作用，随后对膜造成损伤，并与细胞内组分络合；(2)银离子的释放和随后的消毒；(3)形成活性氧（ROS）。这些机制都没有得到最终证实，也没有阐明每种机制在不同类型病原微生物失活中的相对重要性。本研究将合成具有不同平均粒径和比表面积的银纳米粒子，并量化其对病原体消毒机制和速率的影响。拟研究的病原体包括一种病毒（MS2）、一种细菌（大肠杆菌）和一种原生动物（细小隐孢子虫）。实验设计将使我们能够单独确定每种潜在机制，并确定其对每种病原体的总体消毒率的相对贡献。预计这项工作将在几个方面产生更广泛的影响，包括为高中生开设暑期课程，在现有课程中增加环境纳米技术课程模块，并与罗德岛大学工程学生无国界分会（ESWB）合作开发一个服务项目，涉及制造和分销纳米银颗粒，这些纳米银颗粒是专门为波特和平组织生产的陶瓷水过滤器设计的。他们设想后一种努力将成为学生分会的可持续服务项目，向他们介绍发展中国家的水问题，向他们介绍银纳米技术，并为他们的学生分会的服务工作提供资金支持。

0854113CraverNanosilver, the active component of more than 20% of the nanoproducts currently available on the market, is the most commonly used nanomaterial for commercial applications. Approximately 88% of these products have some form of antibacterial or antimicrobial activity. Silver nanoparticles exhibit physical properties that are different from both the ion and the bulk material. Because of their strong antibacterial properties, several studies have shown the potential use of silver nanoparticles in biomedical and environmental applications, such as the treatment of wounds and burns and water disinfection. While the antibacterial properties of silver nanoparticles have been extensively demonstrated, their disinfectant mechanism(s) and kinetics in the inactivation of bacteria, viruses, and protozoa have not yet been elucidated. Indeed, there have been no studies testing the ability of silver nanoparticles to deactivate protozoan pathogens like Cryptosporidium parvum and Giardia lamblia. Previous studies have not addressed the effect of environmental conditions on the antimicrobial properties of silver nanoparticles.The researchers hypothesize that there are three possible antimicrobial processes for silver nanoparticles: (1) direct interaction of the silver particle with the cell membrane and subsequent damage to the membrane and complexation with intracellular components, (2) release of Ag+ ions and subsequent disinfection, and (3) formation of reactive oxygen species (ROS). None of these mechanisms have been conclusively confirmed, nor has the relative importance of each mechanism in the inactivation of different types of pathogenic microorganisms been elucidated. This work will synthesize silver nanoparticles with different mean particle sizes and specific surface areas and quantify their effects on pathogen disinfection mechanism and rate. Pathogens proposed for study include a virus (MS2), a bacteria (E. coli), and a protozoa (Cryptosporidium parvum). Experimental design will allow us to identify each potential mechanism individually and determine its relative contribution to the overall disinfection rate for each pathogen.It is anticipated that this work will have broader impacts in several ways, including a summer program for high-school students, adding an environmental nanotechnology course module to an existing course, and working with the University of Rhode Island chapter of Engineering Students without Borders (ESWB) to develop a service project involving the manufacture and distribution of nanosilver particles specifically designed for use in ceramic water filters manufactured by Potters for Peace. They envision this latter effort to be a sustainable service project for the student chapter that will teach them about developing-world water problems, introduce them to silver nanotechnology, and provide funds to support their student chapter service efforts.