Key factors influencing the optical detection of biomolecules by their evaporative assembly on diatom frustules

作者:Wang Yu; Zhang Deyuan*; Pan Junfeng; Cai Jun
来源:Journal of Materials Science, 2012, 47(17): 6315-6325.
DOI:10.1007/s10853-012-6554-4

摘要

Diatoms have silica frustules with transparent and delicate micro/nano scale structures, multilevel pore arrays, and large specific surface areas. We explored the potential of diatom frustules as biomolecule support for use in optical detection, for example, in protein or DNA biochips and "lab-on-a-chip" sensors. After the solution was evaporated, most particles in the solution assembled on the frustules. Experiments indicated that this phenomenon occurs because of the large specific surface of the frustules; consequently, we studied the capacity of frustules to increase the density of antibodies. The frustules of diatoms Coscinodiscus sp., Navicula sp., and Nitzschia palea were used in this study. The colored particles for optical detection included standard protein, soybean lecithin, bovine serum albumin, and human immunoglobulin G labeled with fluorescein and carbonic black ink. The results showed that the fluorescein isothiocyanate protein was densely assembled on the frustules and exhibited a fluorescence signal that is 2.5 times stronger than that of glass. Compared with the traditional glass substrate, the frustules significantly improved the antibody density and detection signals. The evaporating assembly method was used for measuring the load capacity of frustules for different antibodies; this method can be used to quantitatively bind two or more antibodies to the frustule, which may be valuable in lab-on-a-chip sensors. The design scheme of high-throughput diatom-based biochips was discussed. Through analysis, we hypothesized that diatom frustules with a large specific surface area, high transparency and pore permeability, small sizes and heights, and flat surfaces are particularly suitable for optical detection of biomolecules.