Preparation Of Fluorescence-enhanced Nanocomposite Probe And Its Application In Highly Sensitive Detection

Accurate detection of low-abundance tumor markers(such as mi RNAs)is very helpful for the early diagnosis of major diseases such as cancer.However,the dye molecules used in traditional mi RNAs fluorescence detection methods are easily photobleached and the fluorescence signal detected at single-cell level is weak.Plasmon-enhanced fluorescence(PEF)technology,a powerful signal amplification technology,can effectively overcome the shortcomings of traditional fluorescent dyes such as photobleaching and weak fluorescence signal,which provides effective ideas for solving the above problems.In this paper,using gold nanostars(Au NSTs),triangular gold nanoprisms(Au NPRs),gold nanobipyramids(Au NBPs),and gold nanorods(Au NRs)as substrate materials,signal-enhanced fluorescent nanocomposite probes were prepared based on PEF technology,and which has achieved spatiotemporal controllable and precise imaging.The main work carried out in this paper is as follows:(1)A new type of simple and effective PEF nanocomposite probe was prepared using gold nanostars with 20 highly symmetric hotspots for the first time,which realized the"light-up"high sensitive in situ imaging detection of mi RNA-21 in living cells.By adjusting the thickness of the Si O₂shell layer,the distance between the fluorescent molecules and the PEF substrate material can be adjusted to obtain the best plasmon-enhanced fluorescence performance of gold nanostars,thereby realizing the highly sensitive in-situ imaging detection of mi RNA-21 in living cells.Compared with traditional PEF substrate materials(gold nanorods,gold nanobipyramids,triangular gold nanoprisms,etc.),the gold nanostars constructed in this paper had more hot spots and showed stronger PEF effect.In addition,this probe can not only distinguish cells with different expression levels of mi RNA-21(Hela cells,MCF-7cells,and L02 cells),but can also identify tumor cells in co-cultured cells of normal cells and tumor cells.This work provided new ideas for the design of new PEF nanoprobes and the highly sensitive detection of low-abundance tumor markers.(2)Aiming at the shortcomings of traditional ratiometric fluorescent probes such as low detection sensitivity and"passive recognition"of the target,which can easily lead to false positive signals,this study introduced optical control technology and PEF technology into the design of traditional ratiometric fluorescent probes.A new type of photoactivatable signal amplification ratio fluorescent probe was constructed to realize the highly sensitive spatiotemporal controllable and precise imaging detection of the low-abundance tumor marker mi RNA-155 in cell.Triangular gold nanoprisms(Au NPRs)were used as the substrate material for PEF,the DNA probes containing UV-degradable molecules(PC-linker)were modified to the surface of triangular gold nanoprisms coated with silica shell through covalent bonding,thereby a plasmon-enhanced light stimulus response probe was prepared.When the probe reached the target location in cell,UV light could be used to realize the controllable activation of its sensor recognition function,and then the spatiotemporal controllable and precise imaging detection of the target can be further achieved.In addition,by adjusting the thickness of the silica shell to adjust the distance between the dye molecules and the triangular gold nanoprisms to obtain the best plasmon-enhanced fluorescence effect,the detection sensitivity was further improved.This work has broad application prospects in the design of plasmon-enhanced light stimulus response smart nanoprobes and the high-sensitivity and accurate imaging detection of low-abundance tumor markers.