Photoelectrochemical Biosensor Based On Cadmium-based Quantum Dots

The advantages of photoelectrochemical biosensor include simple equipment,high detection sensitivity and can be miniaturized easily.Photoelectrochemical biosensor can be widely used in the field of biomolecular recognition and detection because of its unique.Superiority,its broad application prospect was viewed.The photoelectric activity of cadmium-based quantum dots was excellent due to the great features that include narrow band gap and the visible light can be absorbed.Moreover,the preparation methods of the cadmium-based quantum dots were simple.Therefore,it is necessary to construct a highly sensitive photoelectrochemical biosensor using the cadmium-based quantum dots.In this paper,a novel photoelectrochemical sensing strategy based on cadmium-based quantum dots was designed,which successfully realizes the detection of target biomolecules,and provides a new idea for photoelectrochemical biosensor research.Chapter 1: This chapter briefly summarized the basic principle,classification and design considerations of photoelectrochemical biosensors;coupling review of the properties of the quantum dots,preparation and biological molecules;the cadmium-based quantum dots in the photoelectrochemical enzyme,DNA,immune cells,sensor application were introduced detailly;and we proposed the related research content and specificity on these bases.Chapter 2: A simple and sensitive sandwich-type photoelectrochemical biosensor with CuO NPs labeled antibody for detection of protein was constructed.The approach relies on antibodies modified by CuO NPs which could release copper ions.The CdS QDs coated on the F-doped tin oxide electrode leading to the ‘‘signal on'' PEC response.In the presence of the target protein,the released copper ions help form the trapping sites to interfere with quantum confinement of quantum dots and thus blocked the escape of photoelectron,leading to a “signal off” PEC method for sensitive detection.This work opens a novel highly sensitive way to detect cancer biomarker carcinoembryonic antigen and provides an efficient applicable tool for PEC bioanalysis.Chapter 3: A novel cascade photoelectrochemical signal amplification sensing strategy was designed and applied in target DNA detection by introducing quantum dots as the accompanying tag.The CdTe QDs was labeled onto a designed sequence of single stranded DNA forming S-QDs,which could be further hybridized with another magnetic bead labeled conjugate,leading to a metastable structure.In the presence of the detecting target,the S-QDs could be released from the metastable structure via toehold strand displacement.With the help of the designed strand(H),the target could be released and triggered the cascade amplification.In the magnetic field,the S-QDs could be easily separated from the reaction mixture and coated on the F-doped tin oxide electrode leading to the ‘‘signal on'' PEC response.The designed cascade amplification photoelectrochemical strategy exhibited a detection limit of 0.76 pM target DNA,and a linear range from 1 pM to 50 nM,indicating promising application in DNA or related analysis.Moreover,compared with other tags such as fluorescent dye,the quantum material leads to less unspecific adsorption and better sensing reproducibility,due to the appropriate nano size and high quantum efficiency.Chapter 4: In this part,we briefly summarized the research results in this paper,and the future prospect in photoelectrochemical biosensors was also evaluate and discussed in the final section.