A solid-phase dot assay using silica/gold nanoshells
1 Lab of Nanoscale Biosensors, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Pr. Entuziastov, Saratov, 410049, Russia
2 Saratov State University, 155 Moskovskaya St, Saratov, 410026, Russia
3 Immunotechnology Group, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Pr., Entuziastov, Saratov, 410049, Russia
4 Philips Classic Laser Laboratories, University of Arkansas for Medical Sciences, 4301 W Markham, Little Rock, AR, 72206, USA
Nanoscale Research Letters 2006, 2:6-11 doi:10.1007/s11671-006-9021-9Published: 17 November 2006
We report on the first application of silica-gold nanoshells to a solid-phase dot immunoassay. The assay principle is based on staining of a drop (1 µl) analyte on a nitrocellulose membrane strip by using silica/gold nanoshells conjugated with biospecific probing molecules. Experimental example is human IgG (hIgG, target molecules) and protein A (probing molecules). For usual 15-nm colloidal gold conjugates, the minimal detectable amount of hIgG is about 4 ng. By contrast, for nanoshell conjugates (silica core diameter of 70 nm and gold outer diameter of 100 nm) we have found significant increase in detection sensitivity and the minimal detectable amount of hIgG is about 0.5 ng. This finding is explained by the difference in the monolayer particle extinction.