abstract
Colloidal silver nanoparticles (NPs) were prepared using the citrate and borohydride reduction methods and were then investigated as fillers in three matrices: unmodified chitosan, water-soluble chitosan and a N-alkyl chitosan derivative. The nanocomposites were used to prepare cast thin films (9-19 mu m thickness) and characterized for their optical and antimicrobial properties. The optical properties of the materials were adjusted either by varying the Ag NPs content in the films (0.5-3.9% w/w) or by using samples of Ag NPs with distinct particle size distributions. The antibacterial activity towards both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae and Escherichia coli) was investigated for the various composites. For the unmodified chitosan nanocomposites, the bactericidal effect depended on their Ag content while such an effect was always observed for water-soluble chitosan and N-alkyl chitosan based materials. This research provides a basis for the evaluation of chitosan/silver composites in applications requiring flexible films with tuned optical properties and antimicrobial activity. (C) 2011 Elsevier Ltd. All rights reserved.
keywords
ANTIMICROBIAL ACTIVITY; QUATERNARY AMMONIUM; CELLULOSIC FIBERS; GOLD; CHEMISTRY; SURFACE; CITRATE; AGENT; RAMAN; SIZE
subject category
Biochemistry & Molecular Biology; Chemistry
authors
Pinto, RJB; Fernandes, SCM; Freire, CSR; Sadocco, P; Causio, J; Neto, CP; Trindade, T
our authors
Carlos Pascoal Neto
Raiz Director
Carmen Sofia da Rocha Freire Barros
Coordinating Researcher
Ricardo Pinto
Researcher
Tito Trindade
Full professoracknowledgements
R. Pinto is grateful to the FCT for a Ph.D. Grant (SFRH/BD/45364/2008). Susana C.M. Fernandes is grateful to the FCT for a Post-doc Grant (SFRH/BPD/70119/2010). We thank Dr Violeta Girao and Dr Marcia Neves for their kind assistance in the AFM and XRD analyses, respectively.