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Integration of fluorescence imaging and electrochemical biosensing for both qualitative location and quantitative detection of cancer cells
摘要： In this work, DNA-templated silver nanoclusters (DNA-AgNCs) with unique fluorescent and electrochemical properties are prepared as dual signal probes for both qualitative imaging and quantitative detection of cancer cells in an integrated system. ITO electrode that has good light transmittance and electric conductivity is employed as a substrate for dual analysis of cancer cells. ITO electrode is firstly modified by AS1141 aptamer, which could selectively bind to nucleolin overexpressed on the surface of a model breast cancer cell, MCF-7 cell line. The composite of mucin 1 antibody (anti-MUC1) and DNA-AgNCs then binds to MUC1 on the surface of captured MCF-7 cell, forming a sandwich-like structure. Therefore, our method allows noninvasive fluorescence imaging and amplified electrochemical detection using a single labeling platform, providing a biocompatible and highly specific method for adequate analysis of cancer cells. Experimental results demonstrate that strong red fluorescence of DNA-AgNCs clearly displays the loading of cancer cells on ITO electrode after dual recognition, and amplified electrochemical signals of DNA-AgNCs enable improved sensitivity toward quantitative analysis with a detection limit of 3 cells.
关键词： ITO electrode,DNA-templated silver nanoclusters,MCF-7 cell,fluorescent imaging,electrochemical detection
更新于2025-09-23 15:22:29
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High performance UV photodetector based on MoS2 layers grown by pulsed laser deposition technique
摘要： Highly efficient ultraviolet (UV) photodetector based on MoS2 layers has been fabricated using pulsed laser deposition (PLD) technique. Systematic layer dependent photoresponse studies have been performed from single layer to 10 layers of MoS2 by varying the laser pulses to see the effect of the number of layers on the photoelectrical measurements. Raman and Photoluminescence studies have been carried out to ensure the growth of high-quality MoS2 layers. Layers of MoS2 grown at 100 pulses were found to exhibit the characteristic Raman phonon modes i.e. E1 2g and A1g at 383.8 cm-1 and 405.1 cm-1 respectively and Photoluminescence (PL) spectra show B exciton peak for MoS2 at around 625 nm suggesting the growth of high-quality MoS2 layers. Atomic force microscopy (AFM) thickness profiling and cross sectional-high resolution transmission electron microscopy (HRTEM) analysis gives the thickness of grown MoS2 to be 2.074 nm and 1.94 nm, respectively, confirming the growth of trilayers of MoS2. X-ray photoelectron spectroscopy (XPS) spectra of the grown trilayer sample show characteristic peaks corresponding to Molybdenum and Sulphur doublet (Mo4+ 3d5/2,3/2 and S 2p3/2,1/2) confirming the chemical state of pure MoS2 phase without the presence of any Molybdenum oxide state. Dynamic photoelectrical studies with Indium Tin Oxide (ITO) as contact electrode upon UV laser illumination show superior responsivity of 3×104 A/W at 24 μW optical power of the incident laser (λ=365 nm) and very high detectivity of 1.81×1014 Jones at a low applied bias of 2 V. The obtained results are highly encouraging for the realization of low power consumption and highly efficient UV photodetectors based on MoS2 layers.
关键词： Pulsed laser deposition technique (PLD),2D material,UV photodetector,ITO electrode,cross-sectional TEM,Raman,MoS2 layers,XPS,AFM
更新于2025-09-23 15:19:57