Detection using a quantum dots/porous silicon optical biosensor based on digital fluorescence images

As a kind of nanostructured material, porous silicon (PSi) has many advantages, including a large specific surface area, easy surface modification, easy biological modification and so on, and it can be used to prepare biosensors with excellent performance. Based on the digital imaging of PSi surface fluorescence, a new low-cost biological detection method is proposed in this paper. Probe DNA that was coupled with semiconductor colloid CdSe/ZnS quantum dots (QDs) interacted with target DNA immobilized on the inner wall of modified PSi. The quantum dots in the reactants were excited in the PSi holes with a Bragg structure to produce fluorescence, which was enhanced by a Bragg mirror. The fluorescence image of the PSi surface was obtained by digital microscopy, and the target DNA was detected by calculating the average gray value of the image. The detection limit of this method for DNA detection is 88 pm, showing that the method can realize low-cost, fast and convenient biological detection.