Biologically produced nanosilver: Current state and future perspectives

Silver nanoparticles are one of the most commercialized nanomaterials. They are widely applied as biocides for their strong antimicrobial activity, but also their conductive, optic and catalytic properties make them wanted in many applications. The chemical and physical processes which are used to synthesize silver nanoparticles generally have many disadvantages and are not eco‐friendly. In this review, we will discuss biological alternatives that have been developed using microorganisms or plants to produce biogenic silver. Until now, only their antimicrobial activity has been studied more into detail. In contrast, a wide range of practical applications as biocide, biosensor, and catalyst are still unexplored. The shape, size, and functionalization of the nanoparticles is defined by the biological system used to produce the nanoparticles, hence for every application a specific biological production process needs to be chosen. On the other hand, biogenic silver needs to compete with chemically produced nanosilver on the market. Large scale production generating inexpensive nanoparticles is needed. This can only be achieved when the biological production system is chosen in function of the yield. Hence, the true challenge for biogenic silver is finding the balance between scalability, price, and applicability. Biotechnol. Bioeng. 2012; 109: 2422–2436. © 2012 Wiley Periodicals, Inc. The biological production of nanosilver is not only an eco‐friendly process; it also creates nanoparticles with unique characteristics. Depending on the microorganism or plant used for the manufacturing process, nanoparticles can be designed such that they have properties which are suitable for specific applications. However, the implementation of biological nanoparticles is mainly an unexplored field due to the complicated large scale production. Therefore, the true challenge for biogenic silver is finding a balance between scalability, price and applicability.