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MnO2 Nanosheet-mediated Ratiometric Fluorescence Biosensor for MicroRNA Detection and Imaging in Living Cells
摘要： MicroRNA (miRNA) plays significant roles in cell proliferation, differentiation and apoptosis, and has been considered to be valuable biomarker for cancer. Accurate and sensitive detection of miRNA is crucially significant for cancer diagnosis and treatment. Here, a MnO2 nanosheet-mediated ratiometric fluorescence biosensor was designed for miRNA detection and imaging in living cells. It contained MnO2 nanosheets acting as DNA carrier, and fluorescent donor (FAM)-labeled hairpin H1 (recognition probe) and fluorescent acceptor (TAMRA)-labeled hairpin H2 (amplification probe). When the biosensor entered cell by endocytosis, MnO2 nanosheets were degraded to Mn2+ via intracellular glutathione (GSH) and the adsorbed hairpins H1 and H2 were released. The intracellular target miRNA-21 hybridized with the recognition unit of H1 to initiate catalyzed hairpin assembly (CHA) and a large amount of H1-H2 duplexes were produced. This brought fluorescent donor FAM and fluorescent acceptor TAMRA into close proximity to produce fluorescence resonance energy transfer (FRET), inducing a ratiometric fluorescent response (donor signal decreased and acceptor signal enhanced) for miRNA-21 detection. Furthermore, this method could be applied to differentiate the expression levels of miRNA-21 in HeLa, HepG-2 and L02 cells. These results indicated that the proposed method possessed great potential in the early diagnosis of miRNA-related diseases.
关键词： MicroRNA detection,MnO2 nanosheets,Ratiometric,Cell imaging
更新于2025-11-21 11:24:58
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Photoelectrochemical biosensor for microRNA detection based on a MoS2/g-C3N4/black TiO2 heterojunction with Histostar@AuNPs for signal amplification
摘要： Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of microRNA-396a based on a MoS2/g-C3N4/black TiO2 heterojunction as the photoactive material and gold nanoparticles carrying Histostar antibodies (Histostar@AuNPs) for signal amplification. Briefly, MoS2/g-C3N4/black TiO2 was deposited on an indium tin oxide (ITO) electrode surface, after which gold nanoparticles (AuNPs) and probe DNA were assembled on the modified electrode. Hybridization with miRNA-396a resulted in a rigid DNA:RNA hybrid being formed, which was recognized by the S9.6 antibody. The captured antibody can further conjugate with the secondary IgG antibodies of Histostar@AuNPs, thereby leading to the immobilization of horse radish peroxidase (HRP). In the presence of HRP, the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 was accelerated, producing the insoluble product benzo-4-chlorohexadienone on the electrode surface and causing a significant decrease in the photocurrent. The developed biosensor could detect miRNA-396a at concentrations from 0.5 fM to 5000 fM, with a detection limit of 0.13 fM. Further, the proposed method can also be used to investigate the effect of heavy metal ions on the expression level of miRNAs. Results suggest that the biosensor developed herein offers a promising platform for the ultrasensitive detection of miRNA.
关键词： S9.6 antibody,Histostar@AuNPs,MicroRNA detection,MoS2/g-C3N4/black TiO2 heterojunction,Photoelectrochemical biosensor
更新于2025-11-14 17:04:02
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A novel photoelectrochemical biosensor for the sensitive detection of dual microRNAs using molybdenum carbide nanotubes as nanocarriers and energy transfer between CQDs and AuNPs
摘要： Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive detection of dual microRNAs (miRNAs), with the detection being based on energy transfer (ET) between carbon quantum dots (CQDs) and gold nanoparticles (AuNPs). The PEC platform consisted of a CQDs@Mo2C nanotube modified ITO electrode. Two hairpin probes (H1 and H2) carrying the Au NPs were used “switch off” and “switch on” the PEC signal of the CQDs, with a close approach of the tagged AuNPs to the CQDs quenching the PEC signal. The introduction of different miRNAs (miRNA-159b and miRNA-166a) altered the interparticle distance between the AuNPs and CQDs, thereby affecting the intensity of the PEC response. This approach allowed the highly sensitive detection of both miRNA-159b and miRNA-166a. The linear range of the biosensor for miRNA-159b and miRNA-166a detection were 0.5–5000 fM, with low detection limits of 0.15 fM and 0.21 fM, respectively. To our knowledge, this is the first reported CQDs-based ET biosensor for the PEC detection of dual miRNAs. Results suggest that this approach offers a promising platform for the ultrasensitive detection of multiple miRNAs.
关键词： MicroRNA detection,AuNPs,Photoelectrochemistry,Energy transfer,CQDs@Mo2C
更新于2025-11-14 17:03:37
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Sandwiching analytes with structurally diverse plasmonic nanoparticles on paper substrates for surface enhanced Raman spectroscopy
摘要： This report describes the systematic combination of structurally diverse plasmonic metal nanoparticles (AgNPs, AuNPs, Ag core–Au shell NPs, and anisotropic AuNPs) on flexible paper-based materials to induce signal-enhancing environments for surface enhanced Raman spectroscopy (SERS) applications. The anisotropic AuNP-modified paper exhibits the highest SERS response due to the surface area and the nature of the broad surface plasmon resonance (SPR) neighboring the Raman excitation wavelength. The subsequent addition of a second layer with these four NPs (e.g., sandwich arrangement) leads to the notable increase of the SERS signals by inducing a high probability of electromagnetic field environments associated with the interparticle SPR coupling and hot spots. After examining sixteen total combinations, the highest SERS response is obtained from the second layer with AgNPs on the anisotropic AuNP paper substrate, which allows for a higher calibration sensitivity and wider dynamic range than those of typical AuNP–AuNP arrangement. The variation of the SERS signals is also found to be below 20% based on multiple measurements (both intra-sample and inter-sample). Furthermore, the degree of SERS signal reductions for the sandwiched analytes is notably slow, indicating their increased long-term stability. The optimized combination is then employed in the detection of let-7f microRNA to demonstrate their practicability as SERS substrates. Precisely introducing interparticle coupling and hot spots with readily available plasmonic NPs still allows for the design of inexpensive and practical signal enhancing substrates that are capable of increasing the calibration sensitivity, extending the dynamic range, and lowering the detection limit of various organic and biological molecules.
关键词： SERS,surface enhanced Raman spectroscopy,interparticle coupling,microRNA detection,plasmonic nanoparticles,paper substrates,signal enhancement,hot spots
更新于2025-09-16 10:30:52
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Using optical tweezers to construct an upconversion luminescent resonance energy transfer analytical platform
摘要： We report a new upconversion nanoparticles (UCNPs) based luminescent resonance energy transfer (LRET) analytical platform by making use of optical tweezers technology. The LRET model is designed by simultaneously conjugating Yb3+ and Er3+ co-doped UCNPs (as the donors) and tetramethyl rhodamine (TAMRA) molecules (as the acceptors) on microspheres to fabricate complex microspheres. Upon a single complex microsphere entering the three-dimensional potential well formed with a tightly focused 980 nm Guassian-shaped laser beam, it is optically trapped and concurrently the upconversion emission is excited, whereby the donor signals are transferred to the acceptors. As a proof-of-concept investigation, microRNA-21 sequences are selected as the targets, by which the distance between the two perfectly matched luminophors is controlled to several nanometers via nucleic acid hybridization. Without the involvement of luminescence amplification strategies, the proposed single microsphere based LRET method shows highly competitive sensitivity with a limit of detection down to 114 fM and satisfactory specificity towards microRNAs detection. Moreover, its practical working ability is demonstrated by credibly quantifying the absolute contents of miRNA-21 sequences in three cancer cell lines and even tracing the targets in as few as 100 cancer cells. Thus, this favorable analytical methodology provides an alternative for bioassays and holds certain potential in biomedical applications.
关键词： microRNA detection,Upconversion nanoparticle (UCNPs),Luminescent resonance energy transfer (LRET),Optical tweezers
更新于2025-09-10 09:29:36