Construction And Applications Of Several Small Biomolecules Fluorescence Sensors

Several small biomolecules are involved in various biochemical reactions in body,their content and state of existence inside the body not only is directly related to the health of an organism,but also plays an important role in the clinical diagnosis of diseases.The fluorescence method has attracted considerable attention because of its high efficiency,sensitivity and rapid detection.The small biomolecules sensor designed using fluorescence principle,which promoted the development of biology,medicine and other related fields.To this end,several fluorescent sensors have been built for ultrasensitive detection of clenbuterol,glutathione,ascorbic acid with simple,low cost.The main contents are as follows:1.A fluorescence resonance energy transfer(FRET)system consisting of carbon dots(C-dots)and gold nanoparticles(AuNPs)for recovered fluorescence detecting of clenbuterol(CLB)was designed.The positively charged C-dots as donor and the negatively charged AuNPs as acceptor bound together through electrostatic interaction,which caused the fluorescence quenching of C-dots for FRET.When in the presence of CLB,adsorption of CLB on the AuNPs surface could induce the aggregation due to the ionic and coordination bonds.When C-dots was added into CLB/AuNPs solutions,the degree of FRET between C-dots and AuNPs were reduced,leading the restoration for fluorescence of C-dots.Under the optimized experimental conditions,we could get a linear relationship between 8-200 nM and the detection limit was 3 nM(S/N=3),which was successfully applied to CLB detection in real pork samples.2.We design for the first time a simple method for colorimetric and ratiometric fluorescent dual-signaling for inner filter effects(IFE)detection of GSH by using C-dots/Ag+/OPD nanosensor.This nanosystem was based on the fact that o-phenylenediamine(OPD)could be oxidized by Ag+ ion to yield 2,3-diaminophenazine(OPDox),a yellow color product,which the maximum fluorescence emission peak at 565 nm and the strong absorption peak at 445 nm.The broad absorption bands of OPDox were overlapped quite well with the emission bands of carbon dots(C-dots)at 455 nm under the excitation wavelength at 380 nm.Thus,OPDox was expected to absorb the emission light of C-dots efficiently for inner filter effect(IFE),resulting in fluorescence quenching of C-dots.In the presence of glutathione(GSH),GSH would inhibite this oxidation progress,which resulted in a decrease of OPDox.The decrease of OPDox would reduced the degree of IFE effectively,which induced the restoration for the fluorescent intensity of C-dots.So the fluorescence ratio intensity F565/F455 was decreased.Based on this phenomenon,we presented a novel colorimetric and ratiometric fluorescent biosensor strategy for GSH detection.Under optimal conditions,the wide linear response ranges were obtained over the range of 20-150 ?M with the low detection limits of 6.67 ?M by ratiometric fluorescence.The wide linear response ranges were obtained over the range of 20-180 ?M with the low detection limits of 9.09 ?M by colorimetry.Moreover,the method can be used for detecting GSH in blood serum.3.A simple and highly selective ratiometric fluorescence sensor for ascorbic acid(AA)sensing based on its molecule structure and the reduction property was reported.The oxidase-like activity of Ag+ ion could oxidize AA to dehydroascorbic acid(DHAA),and combined with o-phenylenediamine(OPD)to form quinoxaline 3-(1,2-dihydroxyethyl)-furo[3,4b]quinoxaline-(3H)-one(DFQ)with the maximum fluorescence emission peak at 434 nm and the strong absorption peak at 345 nm.Then Ag+ ion could oxidize OPD to yield the yellow color 2,3-diaminophenazine(OPDox)with the maximum fluorescence emission peak at 564 nm and the strong absorption peak at 425 nm.When the concentration of AA gradually increased,the product DFQ was increased and the OPDox was decreased.So the ratio of fluorescence intensity(F434/F564)and absorbance(I345/I425)were increased.Futhermore,OPDox was expected to absorb the emission light of DFQ efficiently for inner filter effect(IFE).While AA was increases in the solution,the decrease of the product OPDox effectively inhibited IFE,so the single of ratiometric fluorescent were amplified.Under the optimized experimental conditions,the wide linear response ranges were obtained over the range of 1-100 ?M with the low detection limits of 0.17 ?M and 0.69?M by ratiometric fluorescence and colorimetry,respectively.Notably,the proposed fluorescent sensor exhibits excellent performance and applicability for AA determination in human serum.