Preparation of fixation-free biological sensing electrode and application of fixation-free biological sensing electrode to label-free homogeneous photo-electrochemical pesticide residue detection and cancer diagnosis

Abstract

The invention discloses preparation of a fixation-free biological sensing electrode and the application of the fixation-free biological sensing electrode to label-free homogeneous photo-electrochemical pesticide residue detection and cancer diagnosis. An electroreduction way is adopted to co-modify a phenyldiazonium salt which contains a negative group and the phenyldiazonium salt which does not contain the negative group on the surface of a base electrode. The electrode only adsorbs a single-stranded DNA (deoxyribonucleic acid) and does not adsorb a double-stranded DNA and is high in stability and reproducibility. The electrode can be applied to a label-free homogeneous photo-electrochemical biosensing method. The method comprises a biochemical reaction loop triggered by a target molecule, wherein the biochemical reaction loop contains a label-free DNA hairpin (DNA-1) and a single strand (DNA-2). When the target molecule does not exist, the DNA-1 and the DNA-2 can be both adsorbed onto the surface of the electrode, porphyrin can be adsorbed onto the surface of the electrode by means of the DNA-1 and the DNA-2, and photo-electrochemical signal response is generated; when the target molecule exists, the DNA-1 and the DNA-2 are hybridized with each other, under the action of a polymerase, a large number of DNA-1s and DNA-2s are changed into long double-stranded DNAs, the adsorbing capacity of the DNA-1 and the DNA-2 on the surface of the electrode is reduced, and the porphyrin photo-electrochemical response is reduced.

Description

technical field [0001] The invention relates to the preparation of a fixed-free biosensing electrode capable of specifically adsorbing single-stranded DNA but not double-stranded DNA and the application of a label-free homogeneous photoelectrochemical analysis method. The conversion of single-stranded DNA to double-stranded DNA caused by the target molecule reduces the adsorption of porphyrin molecules on the electrode surface, and the reduction of the photoelectrochemical signal of porphyrin molecules is detected by photoelectrochemistry, so as to realize the detection of target pesticide residues or cancer. Simple, rapid, label-free, homogeneous, highly sensitive detection of markers. Background technique [0002] Photoelectrochemical biosensors are the latest type of biosensors, which have become powerful biochemical analysis and biosensing tools in the fields of disease monitoring and diagnosis, drug analysis, and environmental monitoring. Photoelectrochemical sensors m...

AI Technical Summary

Problems solved by technology

The heterogeneous analysis method mainly has the following defects: on the one hand, the immobilization process of biorecognition molecules on the surface of solid-phase electrodes is usually a very cumbersome chemical modification process, and sometimes the cost of reagents used is very high

The labeling process is also a very complex and difficult chemical modification and purification process, and the cost is extremely high

Second, the diffusion current detection method cannot maximize the use of electrochemically active substances generated / activated in the solution to label DNA, resulting in limited electrochemical signal strength and sensitivity. Third, electrochemical biosensors are mainly produced by current / voltage excitation. Electrochemical signal, the energy form of the excitation source and the detection signal is the same, resulting in a higher background signal or interference signal

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