Strategies For Constructing Fluorescent Biosensing Based On Several Metal Nanoparticles

In this paper,based on the strategies of nucleic acid aptamer,DNAzyme and DNA nanomaterials,two novel biomolecular sensing and detection platforms with high selectivity and high sensitivity were successfully constructed,and the fluorescence analysis of two proteins was realized.Firstly,Upconversion nanoprobes were designed for the analysis of platelet-derived growth factors.In this work,we designed a novel target-triggered DNA assembly probe labeled with upconverting nanoparticles to develop an affinity binding-based amplification strategy.Helper DNA probes containing aptamers and complementary domains are introduced near the hairpin DNA.Due to the selective recognition of two DNA probes and one PDGF-BB,H-DNA probes with aptamers and a DNAzyme domain-blocking domain can form target-triggered DNA assemblies.DNA assembly initiates a DNA strand displacement reaction,which produces unobstructed DNAzymes.These free DNAzymes trigger the amplification of a large number of ring-splitting molecular signals.Therefore,an affinity-binding-based upconversion nanoparticle-mediated amplification strategy for labeling target-triggered DNA assembly probes enables highly selective detection of PDGF-BB in complex biological samples.This strategy can be generalized to other targets,providing a valuable and highly selective method for biological detection.Then,a method for highly sensitive detection of T₄PNK in complex biological systems using ss DNA/Ag NC as a signal probe was developed.This method is constructed based on the hybridization-induced fluorescence enhancement strategy of ss DNA/Ag NC and G-rich Target-DNA.DNA with a5'-OH end is used as a substrate for the DNA phosphorylation process,and G-rich Target-DNA is obtained through a cycle of DNA phosphorylation,ligation,amplification and restriction digestion.The chemical stability of DNA/Ag NC was achieved by treating interfering substances in solution with Na₃H₂IO₆,Ag NO₃,Cu(NO₃)₂solutions.The ss DNA/Ag NC probe can hybridize to Target-DNA if T₄PNK enzyme is present.After hybridization,the fluorescence intensity at 620 nm increased significantly.This method has a wide characteristic linear range(from 5.0×10^-3to 10.0 U/m L)and a low detection limit(1.0×10^-3U/m L)for the determination of T₄PNK enzymes.This makes it potentially useful in areas related to DNA phosphorylation,drug discovery,and medical diagnostics.