Subchronic Oral Toxicity of Silica Nanoparticles and Silica Microparticles in Rats / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the subchronic oral toxicity of silica nanoparticles (NPs) and silica microparticles (MPs) in rats and to compare the difference in toxicity between two particle sizes.</p><p><b>METHODS</b>Sprague-Dawley rats were randomly divided into seven groups: the control group; the silica NPs low-, middle-, and high-dose groups; and the silica MPs low-, middle-, and high-dose groups [166.7, 500, and 1,500 mg/(kg•bw•day)]. All rats were gavaged daily for 90 days, and deionized water was administered to the control group. Clinical observations were made daily, and body weights and food consumption were determined weekly. Blood samples were collected on day 91 for measurement of hematology and clinical biochemistry. Animals were euthanized for necropsy, and selected organs were weighed and fixed for histological examination. The tissue distribution of silicon in the blood, liver, kidneys, and testis were determined.</p><p><b>RESULTS</b>There were no toxicologically significant changes in mortality, clinical signs, body weight, food consumption, necropsy findings, and organ weights. Differences between the silica groups and the control group in some hematological and clinical biochemical values and histopathological findings were not considered treatment related. The tissue distribution of silicon was comparable across all groups.</p><p><b>CONCLUSION</b>Our study demonstrated that neither silica NPs nor silica MPs induced toxicological effects after subchronic oral exposure in rats.</p>

Controlled Release of Drugs from Cellulosic Wound Bandage Using Silica Microsphere as Drug Encapsulator Module.

Controlled-drug-releasing materials show promising applications in medicinal bandages. In addition, one could incorporate drugs to make such bandages more versatile. During this context, silica microparticles were synthesized, during presence of different drugs namely sodium diclofenac, linoleic acid and recienoleic acid. The morphological characterization shows formation of monodispersed, silica microparticles. FT-IR spectroscopy provided the interaction of the drug molecule at its hydroxide (OH) site with oxygen ions on the silica surface. UV–vis spectroscopy showed persistence of the different drugs signature, especially its R group, confirming its antimicrobial activity even after conjugation. Using zone-of-inhibition studies, the antimicrobial studies were done on two microorganisms, namely, Staphylococcus aureus and Escherichia coli. However, the encapsulator module showed controlled release of all drugs for the duration of 48 h. This work demonstrated an effective protocol to prepare antimicrobial patches for controlled drug delivery.