Amperometric Immunosensors For Food Safety Based On Hemin Modified Electrode

Food safety is very important. It is related to the health and safety of people all of the worldand also to the national stability, economic development, special sustainable development andlong-term stability. In recent years, with the development of the industrial technology, the foodsafety problem is getting worse. This problem also caused widespread concern of the community.At present, Gas Chromatography–Mass（GC-MS）, High performance liquid chromatography-mass spectrometry（HPLC-MS）, Atomic absorption spectrometry（AAS）, Atomic emissionspectrometry （AES）,and enzyme-linked immunosorbent assay （ELISA） are usually used fordetection of food safety, however, they are complex, long-time and expensive. Electrehemicalimmunosensors, because of their simple, fast, low-cost, sensitive and easy to carry, are gettingmore and more popular. In this article, we have constructed several amperometric immunosensorsusing hemin for the detection of food safety. The detailed materials are shown as follows:1. A novel immunosensor for rapid determination of clenbuterol （CLB） in food is proposed.The immunosensor is prepared by co-immobilizing CLB antibody （CLB-Ab） and nano-Au/polymer film/Hemin on a glassy carbon electrode （GCE） through layer–by-layer self-assembledmethod. After the immunosensor is incubated in CLB solution at35℃for30min, the access ofactivity center of Hemin is partly inhibited, which leads to a linear decrease of the catalyticefficiency of Hemin by H₂O₂in two CLB concentration ranges from0.1to3.6ng/mL and3.6to300ng/mL. Under optimal conditions, the detection limit for CLB immunoassay is0.02ng/mL（3σ）, this immunosensor can be used to detect CLB level in pig feed sample.2. A novel amperometric immunosensor for escherichia coli （E.coli O157:H7） detection isdeveloped. First, using the Fe₃O₄@ZrO₂nanoparticles （ZMPs） to adsorb enzyme and antibody,then the ZMPs-GOD-E.coli O157:H7-Ab2is gained. Hemin and Polyolefin propylaminehydrochloride-nano-gold complex were fixed on the surface of Screen-printed electrode throughlayer-by-layer self-assembled method, then the SPCE│MCNTs/（Hemin/PAH-Au）5is gained. Inaddition, Firstly, E. coli O157:H7-Ab1was immobilized in the blank96-well plates, then incubatedin the solution of different concentrations of E. coli O157:H7-Ag for30min, and lastly, incubatedin the solution of glucose oxidase labeled E. coli O157:H7-Ab2to obtain some reaction solution with certain concentration of H₂O₂.The catalytic current of the immunosensor is proportional to theconcentration of E.coli O157:H7antigen. The resulting immunosensor offered an excellentamperometric response for E. coli O157:H7ranging from1.0×10³-1.0×10⁴cfu/mL with a detectionlimit of200cfu/mL （3σ）. This immunosensor can be used to detect E.coli O157:H7level in watersample.3. A novel amperometric immunosensor for E. coli O157:H7based on MCNTs-Hemin-PDDA-Au is investigated. Firstly, co-immobilizing the E. coli O157:H7-Ab onto the surface ofScreen-printed electrode（SPCE）, then MCNTs-Hemin-PDDA-Au-E.coli O157:H7-Ab2-E.coliO157:H7-Ag was immobilized on the surface of SPCE/E.coli O157:H7-Ab1. The detection limit ofthe immunosensor sensor in milk is20cfu/mL.