The Application Of Gold Nanoparticle-Based HRP Biosensor In The Food Detection

The enzyme biosensor is a kind of biosensors which uses enzyme as its identification element.Enzyme biosensors not only have the characteristics of electrochemistry biosensors,but also have the characteristics of enzymes,so enzyme biosensors are widely used in food detection.With the rapid development of nanotechnology,gold nanoparticles have been extensively used in the food detection for their specific optical properties electrical properties and good biological compatibility.By using of the gold nanoparticles modified electrode,the electrochemical active of the electrode will be greatly strengthened,and rate of electron transfer is accelerated,and can retain the biological activity of the enzyme in great extent.In summary,when the electrode is modified with gold nanoparticles which have electrical properties and good biological compatibility,the response of current increases rapidly,the detection limit reduces and sensitivities enhance.In this paper,the enzyme biosensors(Au electrode | 1,6-hexanedithiol/gold nanoparticles/HRP)are constructed by the gold nanoparticles which have the sorption on enzyme.The modified electrode is respectively used for the detection of hydrogen peroxide and nitrite residual in food,which could be divided into three aspects as follow:1.In this study,the 1,6-hexanedithiol(HDT)is modified on the surface of gold electrode by the molecular self-assembly system,and then the gold nanoparticles are immobilized on the HDT through the Au-S chemical bond,HRP is immobilized on the gold nanoparticles by the Van der Waals force in the end.Cyclic voltammetry is used to analyze the process of Au electrode | 1,6-hexanedithiol/gold nanoparticles/HRP.It is found out that the establishing process of modified electrode reach an agreement with theoretical assumption.2.In this study,we analyze the electrochemistry reaction of hydrogen peroxide on enzyme modified electrode.Discovering hydrogen peroxide has the reduction on the modified electrode only.The maximum response current is achieved at 6.5 when the pH value between 5 and 8.The steady state response current is achieved as the applied potential at around-0.56V when the range of the applied potential between-0.5 and-0.6V.Under the optimal experimental conditions(pH=6.5,E=-0.56V),the calibration plot can be represent by the following linear relationship:I/?A=2.6964+16.621C/mmol/L[H2O2],R2=0.9991.This biosensor shows a linear range of 2×10-6?1×10-4mol/L and a detection limit of 1.276×10-6mol/L.When we detect H2O2 residual of the milk with this method,the recovery of the sample is 88.6%?91.7%.3.We analyze the electrochemistry reaction of nitrite on enzyme modified electrode.Discovering nitrite has the oxidation reaction on enzyme modified electrode.The maximum response current is achieved at 7 when the pH value between 5 and 8.The steady state response current is achieved as the applied potential around 0.76V.Under the optimal experimental conditions(pH=7,E=0.76V),the calibration plot can be represented by the following linear relationship:I/?A=-0.0424-2.7791 C/mmol/L[NO2-],R2=0.9996.This biosensor shows a linear range of 7.94×10-7?3.98×10-3mol/L and a detection limit of 6.57×10-7 mol/L The recovery of the sample is 96.5%?105%.