Title: Biological responses of silicon nanoparticles
Jonghoon Choi1,2,3, Victoria M. Hitchins3, Peter Goering3, Vytas Reipa1
1Biochemical Science Division, NIST, Gaithersburg, MD 20899
2Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21231
3CDRH, FDA, Silver Spring, MD 20993
Photoluminescent silicon nanoparticles have a bright and stable fluorescence and are promising candidates for use in bio-imaging, cell staining and drug delivery. Biocompatibility of photoluminescent silicon nanoparticles was tested using standard protocols of measuring cytotoxicity and inflammatory responses for micron sized particles with murine macrophage cell line RAW 264.7. The biological responses of silicon nanoparticles (SNs, 3.0 ± 1.0 nm) and silicon microparticles (SMs, 100~3000 nm) were compared in murine macrophage cells. Dry-heat sterilized nano and micro particles were incubated in macrophage cell cultures with and without added lipopolysaccharide (LPS). Cells were examined for gross morphological appearance under with phase contrast microscopy. Cytotoxicity was detected with trypan blue dye exclusion and MTT assays. The supernatants were assayed for production of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) and nitric oxide (NO) by macrophages. Silicon nanoparticles at concentrations up to 20 μg/ml exhibited no statistically significant cytotoxicity or inflammatory responses in RAW cells. However, nano and micro particles at concentrations higher than 20 and 200 μg/ml, respectively, showed a statistically significant increase in cytotoxicity compared to lower concentrations. Fluorescence microscopy showed that Si nanoparticles were associated with macrophage cells. The present study  of murine macrophages, exposed to dry-heat sterilized silicon nanoparticles will help define safety requirements for nanoparticles in biomedical applications.
 Choi, J.; Zhang, Q.; Stratmeyer, M.E.; Wang, N. S.; Reipa, V.; Hitchins, V. M.; Goering, P. L.; " Comparing the biological responses to the photoluminescent silicon nanoparticles with silicon micron-sized particles", J. Appl. Toxicol. 2009, 29, 52-60.
Mentors Name: Vytas Reipa
Science Division (831)
B209/227, MS 8312
Tel: (301) 975-2841
Fax: (301) 330-3447
Is your mentor a Sigma Xi Member? No