Novel Biosensing Technology For The Detection Of Tumor Cells And Telomerase

Recently, Various diseases has been a serious threat to human health. With the deterioration of the human environment, the tumor has been one of the killers to people’s life. Tumor has seriously affected people’s quality and endangered the safety of people’s life. Therefore, achieving tumor cells’ accurate, fast and convenient detection, diagnosis and treatment has very important significance. Telomerase is a common molecular marker of a variety of malignant tumor cells. The detection of telomerase activity for the early detection, development and prognosis of cancer has great significance. This paper combined some novel sensing recognition elements which have emerged in recent years, used electrochemical, photochemical methods to detect tumor cells and telomerase.1. In this chapter, we used cell-aptamers and biocatalytic silver deposition as signal amplification method to establish a electrochemical biosensor in detecting tumor cells. Firstly, thiol labled Ramos cell aptamers was assembled on gold electrode to capture Ramos cells, then Ramos cells also binded with the other aptamer which was labeled biotin, forming the aptamer-cell-aptamers sandwich complexes. And then biotin combined with streptoavidin which was labeled alkaline phosphatase (ALP) ALP on the electrode surface initiated the hydrolysis of ascorbic acid2-phosphate (AA-p) to produce ascorbic acid. The latter, in turn, reduced silver ions on the electrode surface, leading to deposition of the metal silver on the electrode surface, using linear sweep voltammetry LSV)to detect the amount of the deposited silver. The results showed that the anodic stripping peak current was linearly dependent on the Ramos cell in the range of10-106cells, with a detection limit of10cells. The results showed that the sensor has very good detection sensibility. The method of the low detection limit owed to biocatalytic silver deposition amplification.2. The chapter was based on the principle of telomerase amplification reaction and target-induced DNA chain structure-switching to establish a electrochemical biosensor for detecting telomerase activity. Thiol labled telomerase primer (TS) assembled on gold electrode, then hybridzed with ferrocene-tagged short DNA probe, therefore, ferrocene closed to the electrode surface, leading to a high redox current. In the presence of telomerase and mixed nucleotides dNTPs, TS primer probe would be amplified according to repeats sequence TTAGGG, and the amplified repetitive sequence was the complementary base pairs of the hybrid area, induced the folding of the amplified TS primer probe into a hairpin structure, resulting in the release of the ferrocene-tagged short DNA probe from the electrode surface with a substantially decreased redox current. Through the redox peak current could detect telomerase activity. The results revealed that the sensor showed sensitive response to telomerase concentration in a range of100-60000cells, with a detection limit of100cells. The method for detecting telomerase activity has the advantages of high sensitivity, simple operation and the background signal is low, not prone to false negative results etc.3. The chapter was based on the principle of telomerase amplification reaction, target-induced DNA chain structure-switching and gold nanoparticle amplified signal to establish a fluorescent biosensor to detect the telomerase activity. Firstly, thiol probes and fluorescent probes annealing hybrid, then the hybrid duplexes marked on gold nanoparticles, narrowing the distance between gold nanoparticles and FAM. Due to the quenching effect of gold nanoparticles, the fluorescence intensity of FAM greatly reduced. In the presence of telomerase and mixed nucleotides dNTPs, TS primer probe would be amplified according to repeats sequence TTAGGG, and the amplified repetitive sequence was the complementary base pairs of the hybrid area, induced the folding of the amplified TS primer probe into a hairpin structure, resulting in the release of the FAM labeled short DNA probe from the AuNPs surface with a great fluorescence intensity, accordingly, realizing the detection of telomerase activity. The results show that the method can be more sensitive, effective, convenient detection of telomerase activity. The detection range is100-20000cells, with a detection limit of100cells.