▎ 摘　　要

NOVELTY - Biosensor for detecting lead comprises glassy carbon electrode as a working electrode in a three-electrode system, where the reaction end of the glassy carbon electrode surface is modified with reduction-oxidation graphene, the reduction-oxidation graphene surface is modified with gold nano particle. The gold nano particle surface self-assembly with a probe P modified by mercapto and ferrocene, and the probe P is a nucleotide comprises defined sequence of 59 base pairs (SEQ ID NO: 1) as given in the specification. USE - The biosensor/preparing biosensor is useful for detecting lead (claimed). ADVANTAGE - The biosensor: is low in cost, simple and fast, has long service life, strong anti-interference ability, detection accuracy and high efficiency. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing biosensor for detecting lead comprising (i) preparing a glassy carbon electrode, dispersing reduced graphene oxide in water, and then drip coating the surface of the reaction end of the glassy carbon electrode to obtain a reduced graphene oxide modified glassy carbon electrode, (ii) electro-deposit gold nano particles on the surface of reaction end of the reduced graphene oxide-modified glassy carbon electrode to obtain gold nano-particles/reduced graphene oxide-modified glassy carbon electrode, and (iii) adding thiol group and a ferrocene-modified probe P, and a thiol group and a ferrocene-modified probe P on surface of the reaction end of the gold nano-particle/reduced graphene oxide-modified glassy carbon electrode. Fixing gold-sulfur covalent bonds on reaction end surface of the gold nano particle/reduced graphene oxide modified glassy carbon electrode to obtain gold nano particles/reduced graphene assembled with thiol and ferrocene-modified probe P, and modified glassy carbon electrode is a biosensor for detecting lead; and (2) detecting lead using biosensor comprising (1) immersing biosensor for detecting lead in an aqueous solution containing lead ions for 40-120 minutes, taking out and immersing in a phosphate buffer solution containing ferricyanide, and measuring by differential pulse voltammetry, using ferrocene on biosensor as a signal molecule, and ferricyanide in phosphate buffer solution as a signal molecule, and (2) constructing linear regression equation according to changes in the concentration of lead ions and the current value, and the concentration of lead ions in the solution to be measuring can be determining according to linear regression equation.