A Molecular Beacon-like Ag Nanoclusters Fluorescence Probe For Nucleic Acid Detection

With the development of technology,metal nanoclusters are more and more widely used in biomedical field.Silver nanoclusters have become a research hotspot in recent years due to their excellent physical and chemical properties,such as good biocompatibility,photobleaching resistance and photostability.The silver nanoclusters have tunable fluorescence emission synthesized by different DNA templates.By adjusting the sequence of DNA,the multifunctional design and application of silver nanoclusters can be realized.Nucleic acid,as the basic life material,plays an irreplaceable role in life activities,which is related to many diseases as biomarkers.At present,the detection of nucleic acid can effectively assist the judgment of diseases.So,we need more and more accurate and rapid methods to detect nucleic acids.1.Two types of molecular beacon probes were designed,and concentration of目标DNA analysis was carried out.Two molecular beacon probes with higher sensitivity were screened out and used in subsequent experiments.2.Based on the influence of the DNA template sequence on the formation of silver nanoclusters,we designed a label-free molecular beacon to detect DNA sequences.Contrary to the traditional luminescent group-quenching group molecular beacon signal mode,the hairpin-like probe exhibits strong fluorescence due to the enhancement effect of the C-rich sequence.After adding the target DNA,the hairpin-like structure is opened,The C-rich sequence is far away from the silver nanoclusters template sequence,and the fluorescence of the system decreases.The change in fluorescence intensity is proportional to the target DNA concentration and has a good linear relationship in the range of 10-1000 nnmol·L^-1.3.Based on the fluorescence“off-on”strategy,the hairpin DNA probe is used to detect the target DNA.We designed a silver nanoclusters template sequence on the circular structure of the hairpin DNA probe,and the presence of the target DNA can change the structure of the probe.The outcome of the experiment showed that the transformation of the hairpin-like structure had a significant effect on the formation of silver nanoclusters,and the solution containing the target nucleic acid had stronger fluorescence emission than the solution without the target nucleic acid.In the range of1-750 nmol·L^-1,there is a good linear relationship between fluorescence intensity and concentration.In addition,the limit of detection allowed by the detection sensor platform is 1 nmol·L^-1,which is much lower than other studies.Selective experiments can also prove that the probe has a good selectively to recognize target DNA analogs.The DNA detection method studied in this paper has the advantages of low cost,simple operation,high sensitivity and high selectivity,and it can also avoid the complicated steps of labeling dyes.