Graphene Oxide-aptamer Sensor For Adenosine Triphosphate Detection Based On Capillary Electrophoresis

As a new type of fluorescent nano-materials, quantum dots (QDs) have manyunique optical properties, which the conventional organic fluorescent dyes do not possess.So in recent years, QDs have been paid many attentions to, and QDs have been widelyused in many fields, such as fluorescent probes, cell markers, biosensors, medical images,etc. Based on this, the aptamer, which can recognize and combine to ATP specially, wasmodified on QDs surface to prepare fluorescent probes QD-aptamer. And the GO-aptamersensor had been built to detect adenosine triphosphate (ATP) based on capillaryelectrophoresis (CE) and the strong adsorption effect between aptamer and grapheme oxide(GO). The main results are summarized as follows:(1) Oil-soluble QDs were converted into water-soluble QDs by the freshα-dihydrolipoic acid (DHLA) through ligand substitution, EDC was as the coupling agentto prepare fluorescent probes QD-aptamer. And fluorescent probes QD-aptamer werecharacterized by different methods, such as UV-visible absorption spectrum, fluorescenceemission spectrum, capillary electrophoresis, dynamic light scattering (DLS), Zetapotential, etc. It was found that the UV-visible absorption spectrum of QD-aptamerfluorescent probes appeared an apparent absorption peak at260nm, and emissionspectrum of fluorescent probes have a red shift of5nm, which was possibly due toparticle size becoming larger resulting from the connection of QDs and aptamer, the sameconclusion could also be reached from the results of dynamic light scattering (DLS). Fromthe results of capillary electrophoresis, we could find that in the same conditions, themigration time of different samples had a corresponding change. All of these indicatedthat QD-aptamer fluorescent probes was obtained successfully.(2) QD-aptamer fluorescent probes were mixed with a fixed concentration of GOsolution to determine the concentration of GO and QD-aptamer at the maximumadsorption degree. The experimental results show that the final concentrations of GO andQDs-aptamer were0.1μg/mL and300nmol/L respectively. Under such a condition, thefluorescence of QD-aptamer was completely quenched.(3) After determining the concentration of GO and QDs-aptamer at the maximum adsorption degree, different concentrations of ATP solution were added into the mixedsolution of GO and QD-aptamer to explore the influence of ATP concentration on thefluorescence recovery of the probes. The experimental results show that a good linearrelationship between ATP concentration and the electrophoresis peak intensity wasobtained within the range of25-1500nmol/L, R=0.9849, the detection limit was10nmol/L.(4) In this paper，this method was also used to detect the intracellular ATPconcentration of mouse fibroblast cell line NIH-3T3and human cervical cancer cell lineHeLa, and the results were0.31±0.32mmol/L and2.64±0.45mmol/L respectively,While at the same time, a commercial test kit was used to detect the intracellular ATPconcentration of both cell lines，and the results were0.29±0.02mmol/L and2.28±0.05mmol/L respectively. Comparing the test results of two methods, it was found that theresults were consistent, which indicated that our method had obvious advantages to detectlow concentration of target molecule with good usability.