Construction And Application Of Biosensor Based On New Fluorescent Materials

The analysis of life components is of great significance in clinical diagnostics,bioengineering,forensic identification,and environmental monitoring,therefore,it is necessary to establish rapid,sensitive,and low-cost detection method for detecting them.Fluorescence spectrometry is an important tool for biomedical research due to its easy operation,high sensitivity,and speediness.Thus,it is critical to prepare and construct new fluorescent probes with high selective and sensitive response to target molecules.In this paper,different new fluorescent biosensor based on organic and nano-inorganic fluorescent materials were fabricated to detect life-related metal ions,nucleic acid,and protein.The following six tasks have been completed.1.Taking advantage of the high affinity between N,O atoms and metal ions,a Schiff base,N,N‘-bis?salicylidene?-o-phenylenediamine,which showed selectively fluorescence quenching response to Cu²⁺was designed and prepared.Thus,a sensitive and selective method for Cu²⁺detection has been established.The method has been successfully used for quantification of Cu²⁺in soy bean milk powder.Furthermore,the fluorescence switch property of the probe alternately regulated by Cu²⁺and glutathione was explored.2.Taking advantage of stronger affinity of aptamer to its target,a dye-labeled ATP aptamer/graphene oxide?FAM-aptamer/GO?probe with capillary electrophoresis-laser induced fluorescence?CE-LIF?separating detection technique was used for ATP detection.In the presence of ATP,FAM-aptamer would desorbed from the surface of GO with fluorescence recovery of FAM.CE-LIF could separate and detect the ATP-FAM aptamer and avoid the quenching effect of GO in the same solution and influence from other interferents in biological samples,thus effectively improving the sensitivity and accuracy of detection.The approach had been successfully applied to detecting concentration of ATP in HeLa cell,suggesting its good practical application prospect.3.In order to further improve fluorescence signal stability of probe and sensitivity of method,semiconductor quantum dots?QD?with high fluorescent quantum yield and anti-photobleaching was utilized as fluorescent materials.In this work QD-labeled prostate specific antigen aptamer/graphene oxide?PSA-Apt/GO?probe was constructed.With the signal amplification induced by DNase I,sensitivity for PSA detection was markedly improved with the limit of quantification of 0.05 fg mL-1.The experiments certified that this method possessed steady fluorescent signal and excelle nt specificity,and was applied to detection of PSA in human serum.4.Biocompatibility was the key factor that probe could be further applied to analysis of components in cells and in vivo.Recently,graphene quantum dot?GQD?has been attractive in analytical science field due to its low toxicity and photostability.However,functional modification for GQD was difficult;mostly GQD-based probes were synthesized with direct response to target.Herein,nitrogen-doped GQD?N-GQD?which showed selective and sensitive fluorescence enhancement response to Al³⁺was prepared by a facile solvothermal treatment of GO using dimethylformamide.The probe was also utilized to detection Al³⁺in living cells due to its excellent biocompatibility,and its fluorescence switch property was also explored by alternate addition of Al³⁺and EDTA.5.Because of its economy,green,and easy fabrication,fluorescent Ag NC,as a new class of nano-fluorophore,has become a research hotspot in the biomedical analysis area.Especially,synthesis Ag NC with DNA as template could realize one step preparation of DNA functionalized Ag NC.By taking advantage of the phenomenon that fluorescence of DNA-Ag NC could be changed by hybridization with its complementary sequence,probe based on DNA-Ag NC for specific DNA detection could be designed.Herein,the fluorescence turn-on method for detection of human immunodeficiency virus-related DNA was developed through a strand exchange reaction.6.DNA that complemented to PSA aptamer was used to fabricate DNA-Ag NCs.Competitive binding of PSA to aptamer would inhibit fluorescence changing effect of aptamer on DNA-Ag NC.Thus,a label-free and simple DNA-Ag NC/aptamer probe for PSA detection was constructed.In this paper,a variety of biosensors have been constructed using different fluorescence materials to realize the accurate and rapid detection of metal ion,small molecule,antigen and disease-related DNA.These works not only possess excellent practical value,but also provide reference for other probe fabrication.