A simple and reliable qualitative detection of six foodstuff powders using optical thin-film biosensor chips

With the modernization of dietary conceptions, people begin to treat various crops flour as health diet. Unfortunately, species adulteration of flour becomes more and more serious while it is difficult to identify them by the naked eye. Therefore, a reliable molecular biological method of species authentication for common crops flour is required by consumers and authorities. This study developed a reliable and rapid system for detecting six common crops flour (wheat flour, corn flour, potato flour, pea powder, soybean powder and rice flour) using optical silicon thin-film biosensor chips. Aldehyde-labeled capture probes (specific nuclear fragments of endogenous genes of the six food species) were covalently attached to amino-functionalized optical surfaces. Samples containing biotinylated target nucleic acids (PCR amplicon) were then hybridized to this surface. Following hybridization, the immobilized target sequence is incubated with an anti-biotin IgG-horseradish peroxidase conjugate and a precipitable horseradish peroxidase substrate. After incubation, a thin film would be deposited on the chip surface. The mass contributed by the thin film causes a color change visible to the naked human eyes. Using this method, we successfully identified these six food powders. This assay is easy, sensitive, accurate, suitable and can potentially be used as a high throughput for the specific foodstuffs qualitative detection.