Zeolite-supported silver as antimicrobial agents

Use of silver for medical and water purification dates back to thousands of years. During 18th to early 20th century, silver was used for wound management. With the advent of organic antimicrobials, the use of silver faded. Recently, the interest in silver as broad-spectrum antimicrobial has emerged because of the increase in antibiotic resistance. Silver also exhibits inhibitory effects towards fungi and viruses. Currently, silver's antimicrobial effect is exploited in a very diverse set of applications ranging from simple consumer goods to complex medical devices. How and in what form silver is introduced in these applications varies widely. The activity as well as release of silver from these products is environment-dependent and not reported in literature, driven possibly by proprietary needs. Zeolites are a novel platform for storage and release of silver. Since the aluminosilicate framework of the zeolite is negatively charged, silver ions can be readily incorporated by ion-exchange. Nanoparticles of silver anchored on zeolite can also be prepared by simple reduction. Commercial sources of silver ion-exchanged zeolite are available. There have been several recent reviews of antimicrobial properties of silver, and a few of these discuss zeolites, but there has never been a comprehensive review of silver zeolites. This review article fills that void, and covers the research in this subject area over the past two decades. Research in silver zeolites cover use of many different zeolite frameworks, and the applications are driven by incorporating silver zeolite into polymers, textiles, metal coatings. Research on dental/medical materials as well as environmental/consumer products are also prevalent. All these topics are covered in the review. In addition, an exhaustive table with chronological detail of silver/zeolites for quick reference is also provided. A critical assessment of the literature and future possibilities with silver/zeolite conclude this review article. (C) 2018 Elsevier B.V. All rights reserved.