▎ 摘　　要

NOVELTY - Use of light addressable potentiometric sensor based on nano-composite material binding aptamer for detecting low density lipoprotein, is claimed, where detecting low density lipoprotein, involves (a) reducing Oxidized graphene-polyaniline-Heme (RGO-PANI-Hemin) and Gold nanoparticles (AuNPs) composite material for preparing (i) preparation of Reducing oxidized graphene (RGO) (ii) preparing and preparing Hemin solution; (b) the Light addressable potentiometric sensor (LAPS) sensor sensitive portion of modified (i) preparing LAPS chip by pre; (ii) preparing RGO-PANI-Hemin/AuNPs nanomaterial for modifying the LAPS chip after the silylation treatment of the silicon-based LAPS chip after dropping AuNPs solution; (c) the working curve of LDL; followed by and (d) detecting the LDL in the actual sample in the LAPS sensitive portion interface obtained. USE - Light addressable potentiometric sensor based on nano-composite material binding aptamer used for detecting low density lipoprotein. ADVANTAGE - The method has simple operation, time-saving, low cost, and the lowest detection limit is 0.8989 µg/ml. The LDL aptamer has excellent loading ability of the nano-composite material of reducing oxidized graphene-polyaniline- chlorhematin (RGO-PANI-Hemin), and capable of specifically recognizing and quantitatively analyzing the LDL protein. DETAILED DESCRIPTION - Use of light addressable potentiometric sensor based on nano-composite material binding aptamer for detecting low density lipoprotein, is claimed, where detecting low density lipoprotein, involves (a) reducing Oxidized graphene-polyaniline-heme (RGO-PANI-Hemin) and Gold nanoparticles (AuNPs) composite material for preparing (i) preparation of Reducing oxidized graphene (RGO) by weighing single layer Oxidized graphene (GO), adding ultrapure water, using ultrasonic crushing instrument for crushing, dispersing uniformly; adding Ascorbic acid (AA) and stirring at constant temperature by magnetic stirrer, obtaining RGO solution; (ii) preparing and preparing Hemin solution by reducing oxidized graphene-heme, taking the mass ratio of Hemin solution and RGO solution to mix, adding hydrazine hydrate, and placing in the constant temperature water bath boiler water bath heating, stirring, centrifuging, removing the supernatant to obtain RGO- Hemin; (iii) adding the polyaniline PANI solution to the RGO-Hemin solution by reducing the oxidized graphene-polyaniline -Hemine solution, mixing uniformly, then adding 11-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N- Hydroxy succinimide solution (EDC/NSH), stirring, centrifuging, washing and re-dissolving in ultrapure water, freezing and drying to obtain RGO-PANI-Hemin composite material; (iv) preparing AuNPs solution by heating the chloro auric acid solution, stirring to boil, adding the sodium citrate solution into the chloro auric acid solution, continuously stirring until the solution changes from yellow to yellow wine, cooling to obtain AuNPs solution; (b) the Light addressable potentiometric sensor (LAPS) sensor sensitive portion of modified (i) preparing LAPS chip by pre-processing a clean silicon-based LAPS chip, dropping sodium hydroxide solution to activate on the surface, then dripping Mercapto propyl triethoxy silane (MPTES) solution, standing, performing salinization treatment to the silicon wafer, naturally drying to obtain the silanized LAPS chip; (ii) preparing RGO-PANI-Hemin/AuNPs nanomaterial for modifying the LAPS chip after the silylation treatment of the silicon-based LAPS chip after dropping AuNPs solution, surface drying, dropping RGO-PANI-Hemin nano-composite material, standing, drying to obtain RGO-PANI-Hemin/AuNPs sensor sensitive film; (iii) preparing LDLapt/RGO-PANI- Hemin/AuNPs/LAPS sensitive portion by constructing the Low density lipoprotein (LDL)apt solution drop on the RGO-PANI-Hemin/AuNPs sensor sensitive film, incubation, obtaining LAPS sensitive portion interface with LDLapt/RGO-PANI-Hemin/AuNPs/LAPS; (c) the working curve of LDL by drawing (i) dripping the standard LDL solution to LAPS chip sensitive portion interface obtained, incubating, preparing LAPS working electrode; (ii) putting the LAPS working electrode into the LAPS detection system, adding Phosphate buffer solution (PBS) and reference electrode in the detection pool, using LAPS system for detecting, recording the I-V curve; normalizing the I-V curve, and taking blank sample as control, calculating voltage offset; (iii) respectively detecting LDL with different concentrations, taking the concentration of LDL as the abscissa, taking the voltage offset as the ordinate, drawing the working curve, calculating the lowest detection limit of the method; and (d) detecting the LDL in the actual sample in the LAPS sensitive portion interface obtained by dripping the actual sample to be tested, incubating, obtaining the working electrode; adding LAPS working electrode into the LAPS detection system, adding PBS buffer solution and reference electrode in the detection pool, using LAPS system for detecting, recording the I-V curve, normalizing the I-V curve, and taking blank sample as control, calculating voltage offset, using the working curve obtained and according to the voltage excursion of LDL in the actual sample to be measured.