Composite diatom fluorescent sensor substrate enriched with CdSe/ZnS quantum dots on the surface by biofabrication.

Diatoms have developed unique micro- and nanostructures and photonic crystal properties during billions of years of life evolution. In this study, a fluorescence sensor substrate (QD-Diatom) was prepared by biofabrication, and CdSe/ZnS quantum dots (QDs) were immobilized on the surface of diatom biosilica. The concentration of CdSe/ZnS QDs of 7.5×10-3 nmol/mL showed no significant toxicity to the growth of the diatom, which is considered suitable for biofabrication. QD-Diatom preserves the porous structure of diatoms and improves the fluorescence stability of quantum dots. Upon binding to DBs, the fluorescence intensity of QDs was enhanced and the wavelength was red-shifted. The purification of QD-Diatom by chemical reagents and physical calcination was investigated. The results showed that the fluorescence activity of QDs could be maintained and the interference of organic pigments could be removed by soaking in 2 % Sodium Dodecyl Sulfate (SDS) or NaOH and calcining at 180 °C for 1 h. The fluorescence activity of QDs could be maintained and the interference of organic pigments could be eliminated. These results indicate that QD-Diatom can be used as a new type of fluorescent biosensor by simple biofabrication.