RNA Detection Fluorescence Sensing Platform Based On The Novel 2D Nanomaterial Ti₃C₂

Two-dimensional(2D)nanomaterials have been attracted great interest of scientists due to their unique nanosheet structure,large specific surface area and extraordinary physicochemical properties.Among them,transition metal carbon/nitride(MXenes),a novel type of 2D materials,are widely used in the fields of energy storage,catalysis,adsorption,biosensors and composite materials.Compared with traditional2D materials,The Ti₃C₂MXenes,which have larger specific surface area,excellent electrical conductivity and wide absorption in the range of 400-1200 nm,can be used as a good fluorescence quencher.Fluorescence sensing methods based on 2D nanomaterials are widely used in life analysis,disease diagnosis,and other scientific high sensitivity and good selectivity.In this paper,a series of DNA fluorescent nanoprobes were constructed based on the Ti₃C₂MXenes modified by polyacrylic acid(PAA),which converted the recognition process of the target into optical signals and realized the detection and analysis of a variety of RNA.The details are as follows:1.Construction of nucleic acid functionalized Ti₃C₂fluorescent nanoprobe(Ti₃C₂-AS-let 7a-nanoprobe,abbreviated TLNP)and its application in the detection and analysis of let 7a mi RNA.Ti₃C₂MXenes were prepared by one-step etching of lithium fluoride(Li F)and hydrochloric acid(HCl)and its surface was modified with polyacrylic acid(PAA).Finally,the DNA probe labeled with fluorescent group(AS-let7a)was covalently modified by EDC/NHS coupling reaction in Ti₃C₂MXenes.The AS-let 7a modified on the surface of Ti₃C₂MXenes maintains the hairpin configuration,and the fluorophore modified is close to the surface of Ti₃C₂MXenes,the fluorescence resonance energy transfer(FRET)occurs,causing the fluorescence of AS-let 7a to be quenched.When the hybridization reaction between let 7a and AS-let 7a happens to form a double strand,the hairpin structure will be opened,and then causing the fluorophore to move away from the surface of Ti₃C₂MXenes,which destroys the process of fluorescence energy resonance transfer,so as to restore the fluorescence of TLNP.The experimental results prove that TLNP has good selectivity and sensitivity.The linear range of response let 7a is 0-60 n M,and the detection limit is 1.0 n M.This work has revealed that the fluorescent nanoprobes based on the Ti₃C₂MXenes platform have great application potential in biosensors and other fields.2.Construction of Ti₃C₂fluorescent nanoprobe(MB-1-Ti₃C₂)in response to the genomic RNA of hepatitis C virus(HCV)and its application in detection and imaging of HCV.On the basis of the research content 1,we designed a molecular beacon AS-HCV(+)that responed to HCV(+)RNA.Then,we constructed MB-1-Ti₃C₂fluorescent nanoprobe by coupling AS-HCV(+)on the the surface of PAA-Ti₃C₂MXenes through EDC/NHS reaction.MB-1-Ti₃C₂can specifically recognize HCV(+)RNA and open the hairpin structure in AS-HCV(+)through a hybridization reaction.As a result,FRET was disrupted,resulting in fluorescence recovery.The probe shows good selectivity and specificity for in vitro detection,and has a linear range of 0-60 n M with a detection limit of 1.2 n M.In addition,MB-1-Ti₃C₂had high cell penetration efficiency and low toxicity,and it enabled the detection and imaging of HCV(+)RNA in live cells,which is favorable for disease diagnosis and the study of the mechanism of viral infection.3.Construction of dual-response Ti₃C₂fluorescent nanoprobe(MB-Ti₃C₂)for simultaneous detection of HCV positive and negative RNA.On the basis of the research content 2,we constructed MB-Ti₃C₂fluorescent nanoprobe by coupling molecular beacons that specifically respond to HCV(+)RNA and HCV(-)RNA on the surface of PAA-Ti₃C₂MXenes,respectively.The probe can simultaneously detect the two kinds of RNA with high sensitivity and high selectivity in vitro.The detection limit for HCV(+)RNA,HCV(+)RNA are 1.6 n M and 1.4 n M,respectively.This work can provide a new tool for the simultaneous detection of HCV positive and negative strand RNA in vitro.