Research On Nucleic Acid Detection Technology Based On Nanomaterials And Fluorescent Probes

Nucleic acid is the genetic material of life,and it is the basic unit for maintaining the normal operation of various functions of life.Among them,micro RNA is a short non-coding RNA molecule that is involved in cell proliferation,differentiation,apoptosis,and metabolism.Abnormal expression of micro RNA can cause a variety of cancers,so detecting nucleic acids associated with the disease has profound implications for early diagnosis and treatment of the disease.In this paper,nanomaterials with large specific surface area and high surface reactivity are combined with traditional fluorescent biosensors.Using micro RNA let-7a as a detection target,a rapid and sensitive detection system for micro RNA let-7a was established.(1)Non-enzyme amplified micro RNA let-7a detection based on chain displacement reaction and graphene oxide:In the experiment,nanoprobes(ds DNA-Au NPs)were prepared by recognition DNA,hairpin DNA and gold nanoparticles(Au NPs).Graphene oxide(GO)was used as a favorable receptor for fluorescence resonance energy transfer to quench the fluorescence of carboxyfluorescein(FAM)-labeled fuel single-stranded DNA.When the target micro RNA let-7a is present,it will trigger two cascade chain displacement reactions(TSDR)in turn,in this process,the target is recycled and a large amount of the adsorbed fuel DNA is desorbed from the surface of GO,along with the recovery of dye fluorescence.The concentration of micro RNA let-7a is directly proportional to the fluorescence recovery value,and achieved sensitive detection of micro RNA let-7a,this method can achieve a detection limit of 3.9 p M and a good linear range of 0.005-1 n M(R~2=0.9957).Besides,the method is simple and sensitive,and provides a new method for the detection of micro RNA let-7a.(2)Non-enzymatic micro RNA let-7a detection based on carbon dots labeled fluorescent probe and graphene oxide:In the experiment,citric acid was used to synthesize fluorescent carbon dots(CDs),and CDs replaced traditional small molecule fluorescent dye FAM labeled at the end of fuel single-stranded DNA.A micro RNA let-7a detection system was established based on graphene oxide(GO)quenched fluorescence and two TSDRs.CDs-labeled fuel DNA acts as an energy donor and molecular recognition probe,GO acts as a FRET acceptor and a fluorescent quencher.When the target micro RNA let-7a is present,TSDR is triggered twice in sequence,the target is recycled and a large amount of adsorbed fuel DNA(CDs modified)is desorbed from the surface of GO,and the fluorescence recovery of CDs is proportional to the concentration of micro RNA let-7a.Compared with traditional organic dye-labeled DNA,probes synthesized with CDs-labeled DNA have stronger biocompatibility and less toxicity.The method has good sensitivity and selectivity for the detection of micro RNA let-7a,can reach a detection limit of 7.8 p M and a linear range of 0.01-1 n M(R~2=0.9868).This method is easy to operate and provides a new direction for the detection of micro RNA let-7a.It has a better application prospect in future cell detection and various biological analysis,and promotes the cross-development of new nanomaterials and biology.