Construction And Application Of Visible Biosensor System Based On Gold Nanoparticles

Biosensors can make use of biomolecules to detect substances,which have the advantages of high specificity and accuracy,and can be used to detect organic,inorganic,microbiological,biological molecules and metal ions.The visual biosensors could avoid the dependence of the traditional sensors on accessories such as the physicochemical converter and the signal amplifier.In addition,they can greatly simplify the equipment and make the detection more intuitive.In this study,the visual sensing system of gold nanoparticles was constructed by using the color properties of gold nanoparticles and the specific recognition function of biosensors,which were used to detect metal ions Pt???and biological small molecule ATP,respectively.Detection of metal ions Pt???based on aptamer DNA in the gold nanoparticles visual biosensors system.According to the reaction mechanism of DNA aptamer and metal Pt???,a gold nanoparticles visualization biosensor system based on DNA aptamer detection of Pt???was constructed.In the absence of Pt???,the aptamer?AA?can bind to polydiallyldimethylammonium chloride?PDDA?,a cationic polymer,by electrostatic interaction.This reaction inhibited the aggregation of AuNPs induced by PDDA,and AuNPs remained a stable state of dispersion in wine red.In the presence of Pt???,AA would combine with Pt???rather than PDDA to form a hairpin structure.And the free PDDA would promote AuNPs aggregation with the color change from wine red to blue purple.Various experimental conditions,including the concentration of PDDA,AA,pH,Mg²⁺concentration and the reaction time had been researched.Under the optimal experimental conditions,a standard curve was established based on the relationship between the absorbance ratio value of A₆₁₀/A₅₂₀ and Pt???concentration.The linear range was 0.24?M²?M,R² was 0.997,and the minimum detection limit was 58 nM.Meanwhile,other metal ions such as Mg²⁺,Pb²⁺,Ca²⁺,Mn²⁺,Zn²⁺,and K⁺were added to the system,which further proved that the detection system has good specificity and anti-interference.This method is simple and rapid,and has been successfully applied to the detection of Pt???in soil.The results showed that the biosensing system can be successfully applied to the detection of Pt???in real samples.Based on"aggregation-dispersion"effect of gold nanoparticles visual biosensors system for the detection of ATP.In the absence of ATP,single stranded DNA?AHP?can combine with PDDA in terms of electrostatic interaction and and induce the formation of a hairpin structure.The free PDDA in solution induced the aggregation of AuNPs,and the color of AuNPs solution changed to blue purple.The peak intensity of the UV-Vis absorption spectrum got weaker at 520 nm,and red shifted to 610 nm.In the presence of ATP,the hairpin combined with ATP specifically.The hairpin structure of AHP was opened.The free and single-stranded DNA part of AHP binded to PDDA through electrostatic interactions,which inhibited the aggregation of AuNPs induced by PDDA.The color of the solution changed from blue purple to red.Moreover,the absorption peak at 610 nm decreased,and the absorption peak at 520 nm increased,thus enabling the quantitative detection of ATP.Firstly,single-factor experiments were carried out to optimize reaction conditions,such as reaction time and different buffer solutions.And the standard curve was established based on the relationship between absorbance ratio A₆₁₀/A₅₂₀ and Pt???concentration.The linear range was from 20 nM to 100 nM,the R²value was 0.996,and the limit of detection was 1.7 nM.In addition,the results had illustrated that the detection system had a high selectivity and anti-interference ability.Finally,the detection system was successfully applied to the detection of ATP in human serum,indicating that the detection system has a good application prospect.