Fluorescent Detection Of ATP Based On Supramolecular Assembly Of Gemini Surfactant/Aptamer

Fluorescence analysis have received great attention and show great potential applications in environmental and biological process monitoring and disease diagnosis due to their high sensitivity,high selectivity,easy operation,and non-invasion to the samples.Traditional strategies require prelabeling or dual tagging of biomolecules by chemical reactions,which usually require expensive equipment and time-consuming sample preparation.The label-free fluorescence analysis method based on supramolecular assembly shows several advantages:first,the realization and optimization of florescent sensing system are quite easy to realize.Second,this system can effectively avoid the interference caused by fluorescent labeling.Compared with traditional surfactants,Gemini surfactant had better salt resistance.Aptamer is a DNA or RNA sequence with the function of recognizing ligand molecules,which shows excellent resistance to biodegradation and their specificity and affinity towards binding target molecules are equal or superior to those of antibodies.Based on the principle of supramolecular assembly and disassembly,a fluorescence"turn-on"analytical method was constructed for the detection of adenosine triphosphate?ATP?,which used template provided by a better salt-tolerant Gemini surfactant and the selectivity provided by the aptamer.The supramolecular assembly based on Gemini surfactant had higher sensitivity and better salt resistance than traditional surfactants.Furthermore,fluorescence"turn-on"sensors,in which fluorescence intensities increase upon association with biomolecules,are believed to be resistant to interferences and eliminate"false positive"results,making it easy for facile on-site and real-time detection and quantification.The details were as follows1.Driven by electrostatic and hydrophobic interaction,a"turn-off"supramolecular assembly of detecting adenosine triphosphate?ATP?was constructed between positively charged surfactant N,N,N-trimethyl-1-dodecanaminium bromide?DTAB?and negatively charged ATP aptamer?5'-ACCTGGGGGAGTATTGCGGAGGAAGGT-3'?,the hydrophobic dye Nile red was encapsulated in the non-polar interiors of the supramolecular assemblies as fluorescence probe.The supramolecular assembly can show strong fluorescence signal with ATP aptamer and DTAB at a lever lower than the critical micelle concentration?CMC?,which could be confirmed by Fluorescence Spectroscopy.Upon addition of target ATP,the ATP aptamer with guanine?G?-rich sequences selectively bound with ATP to form an aptamer–target G-quadruplex structure.The fluorescence of Nile red was turn off due to the dissembling of the supramolecular assemblies.The detection limit of ATP was as low as 0.36?mol·L^-1 with a good selectivity,and the linear detection range was from 0.5?mol·L^-1 to 10?mol·L^-1.The detection limit was lower than the ATP content in human serum(1?mol·L^-1),which was close to the current research level and has detection significance.However,it was limited for the supramolecular assemblies to detect ATP content in human physiological salt environment due to its poor salt tolerance.2.Driven by electrostatic and hydrophobic interaction,a"turn-on"supramolecular assembly of detecting ATP was constructed between positively charged Gemini surfactant N,N'-didodecyl-N,N,N',N'-tetramethylethane-1,2-diaminium bromide?EDAB?and negatively charged ATP aptamer?5'-ACCTGGGGGAGTATTGCGGAGGAAGGT-3'?,the hydrophobic dye Nile red was encapsulated in the non-polar interiors of the supramolecular assemblies as fluorescence probe.At this time,the fluorescence emission of Nile red was strong due to it was in the non-polar hydrophobic cavity of the assemblies.Although the addition of ATP had the property of stabilizing the G-quadruplex structure of the ATP aptamer,the assemblies cannot disassembly because the electrostatic and hydrophobic interaction of the ATP aptamer and EDAB was still strong at this time.The system was closer to form a larger three-component supramolecular assembly so that the fluorescence emission of Nile red was stronger than before.The detection limit of ATP was as low as 0.14?mol·L^-1 with a good selectivity,and the linear detection range was from 0.5?mol·L^-1 to 10?mol·L^-1.The detection limit was lower than the ATP content in human serum,and the salt tolerance test indicated that the EDAB/ATP aptamer/Nile red supramolecular assembly had good salt tolerance,so the supramolecular assembly shows great promise for detecting ATP in human serum.