Cytotoxicity of Silver Nanoparticle and Chitin-Nanofiber Sheet Composites Caused by Oxidative Stress.
Size-controlled spherical silver nanoparticles (<10 nm) and chitin-nanofiber sheet composites (Ag NPs/CNFS) have previously been reported to have strong antimicrobial activity in vitro. Although Ag NPs/CNFS have strong antimicrobial activity, their cytotoxicity has not been investigated. This study was performed to evaluate the effects of Ag NPs/CNFS on cytotoxicity for fibroblasts in vitro and healing delay of wound repair in vivo, focused on oxidative stress. Cytotoxic activities of Ag NPs/CNFS were investigated using a fibroblast cell proliferation assay, nitric oxide/nitrogen dioxide (NO/NO₂) measurement of the cell lysates in vitro, inhibitory effects of Ag NPs/CNFS on healing-impaired wound repair using diabetic mice in vivo, 8-hydroxy-2'-deoxyguanosine (8-OHdG) immunohistochemical staining of the skin sections, and generation of carbonyl protein in the wound was performed to evaluate cytotoxicity with oxidative stress. Ag NPs/CNFS exhibited cytotoxicity for fibroblasts and a significant increase of total NO/NO₂ levels in the cell lysates in vitro and increased levels of 8-OHdG and carbonyl proteins in vivo. Although wound repair in the continuously Ag NPs/CNFS-treated group was delayed, it could be mitigated by washing the covered wound with saline. Thus, Ag NPs/CNFS may become accepted as an anti-infectious wound dressing.
Department of Oral and Maxillofacial Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. drom636@ndmc.ac.jp.
Jun
J
Kinoda
Research Institute, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. ishihara@ndmc.ac.jp.
Masayuki
M
Ishihara
Department of Biochemistry and Applied Biosciences, University of Miyazaki, Miyazaki 889-2192, Japan. h-hattori@cc.miyazaki-u.ac.jp.
Hidemi
H
Hattori
Research Institute, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. snaka@ndmc.ac.jp.
Shingo
S
Nakamura
Research Institute, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. res309@ndmc.ac.jp.
Koichi
K
Fukuda
Department of Oral and Maxillofacial Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan. yokoe@ndmc.ac.jp.
Hidetaka
H
Yokoe
chitin-nanofiber sheets; cytotoxicity; oxidative stress; silver nanoparticles; wound dressing