Spinning Soy into Gold

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Science  10 Oct 2008:
Vol. 322, Issue 5899, pp. 167-169
DOI: 10.1126/science.322.5899.167d

Many routes exist for making metal nanoparticles but often involve non-water-soluble and/or potentially toxic compounds, a particular concern in preparations for in vivo applications. Shukla et al. prepared gold nanoparticles from aqueous solutions of sodium tetrachloroaurate mixed with soybean extracts. Soybeans contain a wealth of phytochemicals, including proteins, carbohydrates, fats, and isoflavones. Gold nanoparticles formed over the course of a day by direct interaction with soybeans in solution, but better results were achieved using extracts from presoaked soybeans to afford time for the proteins to dissolve. Both low- and high-molecular-weight protein fractions were able to reduce the gold ions, but stabilization of the particles was observed only with the higher-molecular-weight fraction, which effectively coated the particles and prevented aggregation. Particles were stable in salt, histidine, and bovine and human serum albumin solutions and did not show cytotoxicity when tested with human fibroblast cells. Thus, plant matter may be an effective route to making biomedically friendly metal nanoparticles. — MSL

Small 4, 1425 (2008).

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