Remote sensing of Salmonella-specific DNA fragment by using nanoporous alumina modified with the single-strand DNA probe

Abstract

Foodborne Salmonella disease is a major public health concern. Therefore, it is crucial to design a reliable biosensor to the diagnosis of this disease. Herein, we fabricated an interferometric reflectance spectroscopy (IRS) based DNA sensor for the determination of Salmonella-specific DNA fragment concentration. For this purpose, the nanoporous anodic alumina (NAA) was first fabricated. The pore walls of NAA were then functionalized with 3-aminopropyl tri-methoxy silane (NAA-NH2). After that, the amino-terminated single strand DNAsal (ssDNAsal) probe was immobilized on NAA-NH2 by the use of glutaraldehyde (Glu) as cross-linker. To detect the amount of Salmonella-specific DNA fragment, the different concentrations of Salmonella-specific DNA fragment were pumped to the analytical flow cell. Subsequently, methylene blue (MB) was pumped to the analytical flow cell to intercalate between guanine-cytosine base pairs. The intercalated MB into double-strand DNA absorbed the transferred white light to the DNA sensor and therefore, the intensity of the reflected light from the DNA sensor to the charge-coupled device detector decreased. The decrease in the intensity of the reflected light consequent on the decrease in the peak area of the IRS in the wavelength range of 450–1050 nm (peak area450-1050 nm). The decrease in the peak area450-1050 nm had a good linear relationship with the concentration of Salmonella-specific DNA fragment in the range of 0.25–50.0 nM. The limit of detection was found to be 0.01 nM. The fabricated DNA sensor had a good selectivity to Salmonella-specific DNA fragment in the presence of Staphylococcus aureus-specific DNA fragment and Escherichia coli-specific DNA fragment.