The invention relates to a fluorescent sensor, a preparation method thereof and an application of the fluorescent sensor, in particular to a biological fluorescent sensor based on
manganese dioxide nano-sheets and super-sandwiching. By the characteristics that
fluorescent light can be quenched by the
manganese dioxide nano-sheets, single-stranded
DNA (deoxyribonucleic acid) can be adsorbed on the
manganese dioxide nano-sheets, and ds
DNA and other
DNA with a secondary structure can be far away from the manganese dioxide nano-sheets, the fluorescent sensor can be used for detecting
heparin. The preparation method of the fluorescent sensor comprises the following steps of (1) dissolving
a DNA sequence (HP1, HP2 and helper DNA) in buffered solution and storing the buffered solution for
future application; (2) preparing used substances until the concentration is suitable; and (3) culturing the HP1, the HP2, the helper DNA and the used substances in the solution. In the preparation method of the biological fluorescent sensor, unmarked DNA is used. The preparation method is easy to operate and quite low in cost, chemical marks and modification are avoided, and a result shows that the detection result of the sensor on the
heparin is satisfactory. The fluorescent sensor has the advantages of easiness in operation, high sensitivity and low
detection limit.