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Nucleic acid is the main material for storing, copying, and transmitting genetic information. Gene sequencing is of great significance in DNA damage research, gene therapy, mutation analysis, bacterial infection, drug development, and clinical diagnosis. Gene detection has a wide range of applications, such as environmental, biomedical, pharmaceutical, agriculture and forensic medicine to name a few. Compared with Sanger sequencing, high-throughput sequencing technology has the advantages of larger output, high resolution, and low cost which greatly promotes the application of sequencing technology in life science research. Magnetic nanoparticles, as an important part of nanomaterials, have been widely used in various applications because of their good dispersion, high surface area, low cost, easy separation in buffer systems and signal detection. Based on the above, the application of magnetic nanoparticles in nucleic acid detection was reviewed.

Nanomaterials have been widely used to immobilize biomolecules, amplify the signals and concentrate the analytes for detection with good properties including large surface area, good adsorption capacity and high surface activity. In recent years, nanomaterials such as carbon nanomaterials, noble metal nanomaterials, polymers, are widely applied to research and develop immunosensors with high sensitivity and selectivity, which monitor the antigen-antibody reaction for the detection of tumor markers. This review provides an introduction of immunosensors and focuses on the design of electrochemical (EC) immunosensors, electrochemical luminscence (ECL) immunosensors and photoelectrochemical (PEC) immunosensors based on nanomaterials in nearly three years.

A novel molecular imprinted polymer (MIP) electrochemical sensor was successfully fabricated for sensitive detection of carcinomaembryonic antigen (CEA). We used CEA as template, dopamine (DA) as imprinted monomers. Through controlling electropolymerization, a "PDA-CEA"complex was achieved. After elution, the specific cavities adsorbed the target molecules. In addition, polythionine (PTh) and AuNPs were applied as the electrode modifying materials to enhance electron transfer rate and improve detection signal. Using differential pulse voltammetry (DPV) detection, the peak current decreased with the increase in concentration of CEA, and the linear response range of the MIP sensor was from 0.001 ng/mL to 1000 ng/mL with the detection limit as low as 0.2589 pg/mL. The MIP sensor had a low sample consumption, good stability, and high sensitivity, and could become a new promising method for the detection of CEA. Furthermore, this MIP sensor was demonstrated in testing CEA in human serum sample with satisfactory results.

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