The Development Of Biosensors Based On Surface Enhanced Raman Spectra

In this paper, a new type of highly sensitive DNA biosensors which used thenanometer materials technology, rolling circle amplification and hybridization chainreaction techniques was prepared. A specific ultrasensitive detection of trace amountsof biological macromolecules and the DNA was achieved. This thesis will introduceour work in the following three aspects:(1) A novel surface-enhanced Raman scattering (SERS) assay is demonstrated bydeveloping a cross strand-displacement amplifcation (CSDA) method to enhance theSERS signals, which is significant for the detection of of DNA and proteins wasproposed. More biological barcode was modified on the surface of magnetic balls bythe cross strand-displacement amplifcation (CSDA) and the rolling circleamplification (RCA) reaction, which greatly improved the sensitivity of Ramanspectra. Due to a quantitative relationship of the signal intensity of the Raman spectraand the concentration of lysozyme, a low detection limit of5.8×10-15M for lysozymeis obtained.(2) A novel proximity-dependent isothermal cycle amplification (PDICA)strategy has been proposed and successfully used for the determination of cocainecoupled with surface enhanced Raman scattering (SERS). In the presence of targetmolecules, two label-free proximity probes can hybridize with each other andsubsequently opens the hairpin connector-probe to perform the PDICA reactionincluding the target recycling amplification and strand-displacement amplification.Asa result, due to a quantitative relationship of the signal intensity of the Raman spectraand the concentration of cocaine, a low detection limit of0.1nM for cocaine isobtained.(3) In this experiment, the distribution of the tumor markers on the surface of thecell was detected by Raman spectral imaging. One protein was chosed to connect the cell and the biological barcode. Then, the cell was detected by the Raman spectral anddata was transformed into the images. We conducted the RCA experiments to increasethe intensity of the Raman spectrum. From the figure we can make a judgment on thedistribution of this protein on the cell surface according to color change.