| Catechol(CC)is an isomer of dihydroxybenzene,which is widely used in cosmetics,tanning,pesticides,flavoring agents,medicines,antioxidant,dye and photography chemicals.Due to their high toxicity and low degradability in the ecological environment,they are considered as environmental pollutants by the US Environmental Protection Agency(EPA)and the European Union(EU).However,phenols will not only damage the environment,but also pose a certain threat to human health.The International Agency for Research on Cancer(IARC)has categorized CC as a Group 2B,thinkable human carcinogen.Therefore,it is of great significance to detect it promptly and sensitively.Recently,electrochemical methods are extensively used for the detection of numerous analytes with CT,owing to its low price,rapid response and transportability along with high sensitivity paralleled to presented traditional analytical methods.Horseradish peroxidase(HRP)electrochemical biosensor is a novel phenol detection instrument.However,HRP is very sensitive to temperature,which seriously limits the application of HRP immobilized enzyme sensor.It has been reported that the immobilized enzyme sensor is prepared by immobilizing the free horseradish peroxidase and then preparing the immobilized enzyme material.It can not only improve its detection performance,but also broaden its application range.Based on this,a new immobilization system of horseradish peroxidase was designed in this experiment.In this system,the phase-change microcapsules with self-regulation of heat and temperature were introduced into the HRP immobilized carrier,which successfully improved the temperature stability of the immobilized HRP.In the design process,according to the optimum temperature of 35? for immobilized HRP,n-eicosane,a phase changematerial matched with its temperature range,was selected as the core material.At the same time,to improve the electrochemical performance,polypyrrole and titanium dioxide with high biological affinity were selected as microcapsule shells,and a phase change microcapsule with multi-layered structure was formed.The designed multi-layer shell microcapsules successfully prevent the phase change core material from leaking when melting 'at elevated temperature.At the same time,the second layer of the MEPCM largely increases the specific surface area of the carrier.At the same time,it allows abundant binding sites exist between the surface and enzyme.The results show that the immobilized horseradish peroxide catechol biosensor designed in this experiment shows excellent thermal cycle stability.At the same time,the coating of PPy reduced the electron transfer impedance of TiO2 and realized the direct electrochemical behavior of HRP.Under the best experimental conditions,the HRP@TiO2@PPY@n-20 immobilized enzyme sensor can keep good detection ability at 25?60?.At room temperature,the calibration curves for CC was obtained in the range of 9 ×10-6 to 9 ×l0-3 mol L-1,respectively.The detection limits were 3.26× 10-6 mol L-1(S/N=3)with sensitivity of 5.57×10-6 A/mM-1 cm-2.Under extreme conditions conditions,the electrochemical sensor based MEPCMs shows a wide linear response in the concentration range of 0.9 mM to 7 Mm for CC and respectively with a detection limit of 5.38×10-6 mol L-1,(S/N=3).In addition,the proposed sensor shows good selectivity and stability along with good thermostabilityThe obtained results clearly demonstrate that the HRP@TiO2@PPY@n-20 composite can be an advanced electrode material for the real time sensing of catechol under different temperature conditions and provides a broad application space for the content control of catechol in various liquids. |
PDF Full Text Request