Ciencias

J. Braz. Chem. Soc., Vol. 21, No. 6, 949-959, 2010. Printed in Brazil - ©2010 Sociedade Brasileira de Química 0103 - 5053 $6.00+0.00

Review

Potential Use of Silver Nanoparticles on Pathogenic Bacteria, their Toxicity and Possible Mechanisms of Action
Nelson Durán,*,a Priscyla D. Marcato,a Roseli De Conti,a Oswaldo L. Alves,a Fabio T. M. Costab and Marcelo Brocchib
a

Instituto deQuímica and bInstituto de Biologia, Universidade Estadual de Campinas, 13083-970 Campinas-SP, Brazil

As propriedades da prata são conhecidas há muitos anos. Recentemente, as nanopartículas de prata têm chamado a atenção por sua atividade antimicrobiana que oferece a possibilidade de uso com propósitos médicos e de higiene. Estas nanopartículas de prata em diferentes formulações, com diferentes formase tamanhos, exibem atividades antimicrobianas diferentes. Entretanto, os mecanismos da atividade antimicrobiana de íons e de nanopartículas, assim como sua toxicidade em tecidos humanos não estão totalmente esclarecidos. Esta revisão avalia o uso potencial de nanopartículas de prata no controle de patogênicos com ênfase sobre sua ação contra bactérias patogênicas, sua toxicidade e possíveismecanismos de ação. The antimicrobial properties of silver have been known for thousands of years. Recently, silver nanoparticles have gained attention because of their antimicrobial activity which offers the possibility of their use for medical and hygiene purposes. Indeed, silver nanoparticles in different formulations and with different shapes and sizes exhibit variable antimicrobial activity.However, the mechanisms of antimicrobial activity of silver ions and silver nanoparticles, and their toxicity to human tissues are not fully characterized. This review evaluates the potential use of silver nanoparticles to control pathogens with emphasis on their action against pathogenic bacteria, their toxicity and possible mechanisms of action. Keywords: silver nanoparticles, silver ions,antimicrobial activity, toxicity

1. Introduction
There is a growing concern about the emergence and re-emergence of drug-resistant pathogens such as multiresistant bacterial strains, fungi and parasites.1 Therefore, the development of new antimicrobial compounds or the modification of those available in order to improve antimicrobial activity for therapy, antisepsis or disinfection is a high priorityarea of research. In this endeavor, nanotechnology provides a means to modify key features of different materials, including metal nanoparticles.2,3 The inhibitory and bactericidal activities of silver ions have long been known.4-7 Some forms of silver have been demonstrated to be effective against burn infections, severe chronic osteomyelitis, urinary tract infections and central venous catheterinfections.8 Based on these results, many silver-based antimicrobial materials have become available and several others are under development in research laboratories.2,9 In addition to
*e-mail: duran@iqm.unicamp.br

antimicrobial activity, the mechanisms of action and toxicity are also of paramount importance and several studies are under way to better elucidate these aspects. Metallicnanoparticles can be obtained by physical, chemical or biological methods. However, biological synthesis is reliable and eco-friendly, and has received particular attention. In fact, a number of different species of bacteria and fungi are able to reduce metal ions producing metallic nanoparticles with antimicrobial properties.10-16 Recently, efficient antibacterial activity was observed against multidrugresistant and highly pathogenic bacteria, including multidrug resistant Staphylococcus aureus, Salmonella typhi, Staphylococcus epidermidis and Escherichia coli by silver nanoparticles produced by the fungus F. acuminatum.17 Additionally, plant extracts can also be used to obtain metallic nanoparticles.18,19 This review discusses the current worldwide research on the use of silver nanoparticles...