Porous Silicon Biological Detection Based On Digital Image Method

As a nanostructured material,porous silicon(PSi)has many advantages,such as large specific surface area,easy surface modification,easily biological modification and so on.At present,PSi biosensors have been widely used,and fluorescence-labeled PSi biosensors are detected by fluorescence spectrometer.Fluorescent-labeled PSi biochips cannot be detected using a fluorescence spectrometer.In this paper,a new biological detection method based on digital fluorescence image is proposed.The fluorescence image of PSi quantum dot biosensor is obtained by digital imaging device under 488 nm visible laser excitation.Detection of biological concentration by calculating the average gray value of image.The method can achieve a detection limit of DNA of 88 pM,thereby achieving rapid,low-cost and convenient biological detection.The following is the main research content of this paper:1.PSi with single layer and Bragg mirror was prepared by activating carboxyl groups on the surface of water-soluble quantum dots(QDs)by EDC and sulfo-NHS.The high reflective band range of PSi with Bragg mirror includes the emission peak range of QDs.Using digital imaging equipment to obtain PSi images of single-layer and Bragg mirrors.2.Fabrication and functionalization of PSi Bragg mirrors by electrochemical method.Using QDs-coupled DNA as probe,target DNA of different concentration was modified on the surface of PSi Bragg mirror,and then hybridized with target DNA.The fluorescence images of different concentration sensors are obtained by digital imaging equipment.The average gray value is calculated by image processing software,and then the DNA concentration is calculated according to the average gray value.At the same time,fluorescence spectrometer was used to detect different concentration sensors,and the detection limit was 8pM.Although the detection limit of digital image method is slightly lower than that of fluorescence spectrometer,fluorescence spectrometer is expensive.Digital image method only needs ordinary optical elements and digital microscope.In addition,digital image method can also beused for biochip detection.3.We have successfully fabricated PSi chips with Bragg structure.QDs-coupled DNA was used as fluorescent probe,and then target DNA of two concentrations was modified on the surface of PSi chips.Two kinds of PSi Bragg biochips were prepared by reacting the probe with target DNA.Finally,the image of PSi Bragg biochip was successfully obtained by digital imaging equipment,which laid the foundation for parallel detection of biochip.