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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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Functionalized and oxidized silicon nanosheets: Customized design for enhanced sensitivity towards relative humidity
摘要： The use of completely oxidized two-dimensional (2D) silicon nanosheets (SiNSs) represents a novel approach for the application of 2D silicon-based materials in the nanoelectronics field. Densely stacked and highly porous oxidized SiNSs (OSiNSs) act as a sensitive layer for humidity detection. Due to the oxidation-caused porosity of the SiNSs and the possibility functionalize the 2D surface with hydrophilic groups, this hybrid material exhibits an extremely good sensitivity towards relative humidity (RH). In this work, precise tuning of the SiNSs’ sensing properties by their functionalization is demonstrated. In particular, the modification with methacrylic acid (MAA) groups, leading to SiNS-MAA, and the subsequent deposition on interdigitated electrodes double the capacitance value in the range of 20-85%RH. These values were achieved after the full oxidation of SiNS-MAA in ambient conditions. The mentioned changes in capacitance are extremely high compared to the response of the so far known common polymer humidity sensors. Contrary to that, this response is neutralized when the SiNSs are functionalized with tert-butyl acrylic acid (tBMA), a rather hydrophobic functional group. The fabricated devices show, how the specific functionalization of SiNSs serves as a reliable tool to provide sensitivity towards RH. Similar approach, based on tuning the functionality, can be applied to achieve e.g., sensor array selectivity. For this purpose, the functional groups on the surface of the nanomaterial can be further modified. Additional molecules with sensitivities towards various surrounding conditions could be attached. Furthermore, these functional molecules can be used for subsequent (bio)molecule immobilization, which can serve as sensitive molecular groups towards surrounding substrates and gases. However, one of the main challenges in sensor technology is to find a highly selective solution: a sensor system capable to differentiate among different vapor species. The described strategy can serve as an access towards new and promising solutions, which can help to face this issue in modern nanomaterials-based technology.
关键词： two-dimensional materials,porous silicon,functionalization,silicon nanosheets,hybrid systems,moisture content
更新于2025-11-21 11:20:48
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Architectural Design of Photodetector Based on 2D (MoS <sub/>2</sub> ?Nanosheets)/1D (WS <sub/>2</sub> ?Nanorods) Heterostructure Synthesized by Facile Hydrothermal Method
摘要： Hydrothermal technique is utilized to synthesize 2D/1D heterostructure based on MoS2 (nanosheets)/WS2 (nanorods) for photodetector application. The sensor was fabricated by drop cast technique. X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR) Spectroscopy, Field-Emission Scanning Electron Microscopy (FESEM), UV-Visible (Uv-Vis), Raman and X-Ray Photoelectron spectroscopy (XPS) were performed to characterize the synthesized sample. The optical sensor based on heterostructure was studied as a function of laser wavelength (λex): 635 nm (red), 785 nm (infra-red) and 1064 nm (near infra-red) and power of illuminated laser sources. The device exhibits photoresponsivity in a broadband range from the visible to the near-infrared (600–1065 nm, yield a photoresponsivity (Rp) = 15 μA/W and high speci?c detectivity (D?) = 24 × 106 jones at λex = 785 nm). The photoresponsive characteristics of MoS2/WS2 heterostructure hold the principle of simple power law.
关键词： MoS2 nanosheets,photodetector,hydrothermal method,WS2 nanorods,2D/1D heterostructure
更新于2025-11-21 11:01:37
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g-C3N4 nanosheets functionalized silicon nanowires hybrid photocathode for efficient visible light induced photoelectrochemical water reduction
摘要： We report the fabrication of hybrid Si nanowires @ g-C3N4 nanosheets based photocathode using metal assisted chemical etching and facile liquid exfoliated process. The g-C3N4 nanosheets on Si nanowires form hybrid heterojunction photocathode, which exhibits an enhanced photon induced water reduction activity enabling higher photocurrent density of 22 mA cm?2 with applied bias photocurrent conversion efficiency of 4.3% under visible light irradiation. The onset potential of cathodic photocurrent is positively shifted from 41 to 420 mV vs. RHE with the short circuit current density, Jsc of 0.50 mA cm?2 owing to superior charge transport in hybrid photocathode as compared to pristine Si nanowires for hydrogen evolving reaction at pH～7. The electrochemical impedance spectroscopy measurement elucidates the interface layer of g-C3N4 nanosheets form hybrid heterojunction with Si nanowires that result significant increment in solar water reduction activity owing to low charge transferred resistance with high life time of excited electrons in conduction band. This strategy may open to design a new low cost stable hybrid heterostructure photocathode for solar induced water reduction.
关键词： Solar water reduction,Si nanowires,Photocathode,g-C3N4 nanosheets,Interface
更新于2025-11-21 11:01:37
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Colloidally synthesized defect-rich $$\hbox {MoSe}_{2}$$ MoSe 2 nanosheets for superior catalytic activity
摘要： Transition metal dichalcogenide (TMD) nanosheets (NSs) with defect-rich and vertically aligned edges are highly advantageous for various catalytic applications. However, colloidal synthesis of defect-rich NSs with thickness variation has been a challenging task. Here, we report a colloidal synthesis of 2H-MoSe2 NSs having a large number of defects and vertically aligned edges, where the thickness is varied by changing the amount of coordinating solvent. The Se-vacancies in these NSs have introduced defect sites which are corroborated by the presence of additional vibration modes in Raman spectra. These NSs exhibit electrocatalytic hydrogen evolution reaction performances with a low overpotential (210–225 mV) at 10 mA cm?2 current density and a small Tafel slope (54–68 mV per decade). Moreover, these MoSe2 NSs are also employed as counter electrodes (CEs) for the fabrication of dye sensitized solar cells via a cost-effective and simplified procedure. The power conversion efficiencies of 7.02 ± 0.18%, comparable with Pt CE (7.84 ± 0.10%) could be routinely achieved. These results demonstrate a novel synthetic strategy to prepare layered TMDs with superior catalytic applications.
关键词： counter electrode,Transition metal dichalcogenides,dye sensitized solar cells,MoSe2 nanosheets,hydrogen evolution reaction
更新于2025-11-19 16:56:35
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Constructing electrostatic self-assembled 2D/2D ultra-thin ZnIn2S4/protonated g-C3N4 heterojunctions for excellent photocatalytic performance under visible light
摘要： 2D/2D ultra-thin ZnIn2S4/protonated g-C3N4 nanocomposites (ZnIn2S4/pCN) are fabricated by electrostatic self-assembly strategy between negatively charged 2D ultra-thin ZnIn2S4 nanosheets and 2D protonated g-C3N4 nanosheets. The optimized ZnIn2S4/pCN (5:3) shows excellent photocatalytic activity toward H2 production (~8601.16 μmol·g?1·h?1) under visible light. In addition, ZnIn2S4/pCN also exhibits superior visible-light-driven photocatalytic tetracycline degradation efficiency, about ~4.13 and ~2.28 times higher than protonated g-C3N4 and ultra-thin ZnIn2S4, respectively. The optimal ZnIn2S4/pCN (5:3) also has good photostability. The excellent photocatalytic activity of ZnIn2S4/pCN can be attributed to the unique 2D/2D heterojunctions, which are obtained by electrostatic self-assembly. The intimate interfacial contact and larger contact areas promote the separation and migration of photogenerated carriers, which contribute to the improvement of photocatalytic activity and photostability. Our research on the 2D/2D nanocomposites provides a scalable solution for the research of efficient and active photocatalysts.
关键词： protonated g-C3N4,ultra-thin ZnIn2S4 nanosheets,electrostatic self-assembly,2D/2D
更新于2025-11-19 16:46:39
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Ultrathin Ti3C2 Nanosheets based “off-on” Fluorescent nanoprobe for Rapid and Sensitive Detection of HPV Infection
摘要： MXenes as a new class of 2D materials have recently been widely applied in energy storage, electrocatalysis, sensors, adsorption, water purification, and so on, due to their tunable versatile properties. Herein, we demonstrate a simple, rapid and highly-sensitive sensing platform based on ultrathin two-dimensional MXene Ti3C2 nanosheets (Ti3C2 NSs) for selective analysis of Human papillomavirus (HPV), a major human pathogens and causative agents of cervical cancer. Ultrathin Ti3C2 NSs, obtained by exfoliating their layered HF-etched powder, exhibit high fluorescence quenching ability to dye-labeled single-stranded DNA (ssDNA) and different affinities for ssDNA and double-stranded DNA (dsDNA). Under the fluorescence quenching effect of Ti3C2 NSs, ssDNA probe (P) shows the minimal fluorescent emission. After the formation of duplex structure with its complementary target, ssDNA (T), the fluorescence intensity enhances evidently. Exonuclease III (Exo III) was used to improve the sensitivity by promoting more fluorescence enhancement. This magnified fluorescent sensor for HPV-18 detection shows a low detection limit of 100 pM and a high specificity. Furthermore, the developed DNA sensor can be employed to determine PCR amplified HPV-18 from cervical scrapes samples. It highlights ultrathin Ti3C2 NSs as a potential candidate for construction of fluorescence DNA biosensors with excellent performances.
关键词： DNA hybridization,Ti3C2 nanosheets,HPV,Fluorescent detection
更新于2025-11-19 16:46:39
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Grafting cobalt sulfide on graphene nanosheets as a counterelectrode for dye-sensitized solar cells
摘要： In the present work a composite counter electrode of graphene nanosheets grafted cobalt sulfide was fabricated through a facile synthetic route, in which cobalt sulfide nanoparticles were successfully grafted on the surface of graphene nanosheets. Used as a counter electrode in DSSC, a power conversion efficiency of 7.28% can be achieved. Such a result might be contributed to the facts that this counter electrode composed of graphene nanosheets grafted cobalt sulfide has a good stability and electrochemical catalytic performance toward triiodide reduction reaction.
关键词： photovoltaic performance,graphene nanosheets,cobalt sulfide,counterelectrode,Dye-sensitized solar cell
更新于2025-11-14 17:04:02
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Development of a fluorescence immunoassay for highly sensitive detection of amantadine using the nanoassembly of carbon dots and MnO2 nanosheets as the signal probe
摘要： Fluorescence immunoassays are rapid, convenient and cost-effective for the sensitive quantitation of chemical contaminants in foodstuff. In this study, a competitive fluorescence ELISA was developed for the sensitive detection of amantadine (AMD) based on the alkaline phosphatase (ALP)-triggered fluorescence "turn-on" signals. As a fluorescence substrate, carbon dots (CDs) were adsorbed onto the surface of the MnO2 nanosheets (NSs) and formed a nanoassembly of p-CDs@MnO2 NSs which results in the fluorescence quench of CDs. The ALP labelled on antibody could catalyze the hydrolysis of the 2-phospho-L-ascorbic acid into ascorbic acid. The latter could then reduce and decompose the MnO2 NSs, which was accompanied by the release of CDs from the surface of MnO2 NSs and led to the fluorescence recovery of CDs. The change of the fluorescence intensity is related to the concentration of AMD in solution and thus could be applied to detect AMD in an ALP-based ELISA system. The fluorescent ELISA showed a linear detection for AMD in the range of 0.048 ng mL?1 to 1.1 ng mL?1 with a detection limit (LOD) of 0.035 ng mL?1. The novel fluorescent ELISA shows potential for the highly sensitive detection of AMD and other analytes in food analysis.
关键词： manganese dioxide nanosheets,carbon dots,fluorescent immunoassay,amantadine
更新于2025-11-14 17:04:02
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A direct one-step synthesis of ultrathin g-C3N4 nanosheets from thiourea for boosting solar photocatalytic H2 evolution
摘要： Two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets, as the promising photocatalyst with fascinating properties, have become a 'rising star' in the field of photocatalysis. Although g-C3N4 nanosheets exfoliated from the bulk g-C3N4 powders are extensively emerged, developing a simple synthetic approach is still full of challenge. To this end, here we report a direct polymerization strategy to fabricate the ultrathin g-C3N4 nanosheets, that is only heating treatment of thiourea in air without addition of any template. The photocatalytic activities of as-prepared samples were evaluated by photoreduction of water to hydrogen (H2) using triethanolamine as sacrificial agent and Pt as co-catalyst under visible-light irradiation (λ > 420 nm). As a result, our few-layered g-C3N4 nanosheets with an average thickness of 3.5 nm exhibit a superior visible-light photocatalytic H2 evolution rate (HER) of 1391 μmol g?1 h?1 and a remarkable apparent quantum efficiency of 6.6% at 420 nm. Eventually, the HER of as-fabricated ultrathin g-C3N4 nanosheets is not only much higher than the dicyandiamide-derived g-C3N4 or melamine-derived g-C3N4, but also greater than the thermal-oxidation etched g-C3N4 nanosheets under the same condition.
关键词： g-C3N4 nanosheets,Template-free polymerization,Solar energy conversion,2D materials,Photocatalysis,One-step synthesis
更新于2025-11-14 17:03:37