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Dual-Channel Photoelectrochemical Ratiometric Aptasensor with Up-converting Nanocrystals Using Spatial-Resolved Technique on Homemade 3D Printed Device
摘要： A near-infrared light (NIRL)-activated ratiometric photoelectrochemical (PEC) aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF4:Yb, Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A1) and capture DNA (CA) were modified onto two working photoelectrodes (WP1 and WP2) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A2) were immobilized on the surface of functional WP2 for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP1, whereas the binding of the CEA with Au NP-A2 could be released from the WP2 thanks to the highly affinity of CEA toward A2. The dual signal readout with the 'signal-off' of WP1 and 'signal-on' of WP2 were employed for the spatial-resolved PEC (SR-PEC) strategy to detect CEA as an analytical model. Combining NaYF4:Yb, Er UCNPs@CdTe nanocrystals with spatial-resolved model on 3D printing device, the PEC ratiometric aptasensor based on steric hindrance effect and exciton-plasmon interactions (EPI) exhibited a linear range from 10.0 pg mL-1 to 5.0 ng mL-1 with a limit of detection of 4.8 pg mL-1 under 980 nm illumination. The SR-PEC ratiometric strategy showed acceptable stability and reproducibility with a superior anti-interference ability. This approach can provide the guidance for the design of ratiometric, multiplexed and point-of-care biosensors.
关键词： 3D printing device,upconversion nanoparticles,Photoelectrochemical biosensor,ratiometric,spatial-resolved technique,carcinoembryonic antigen
更新于2025-09-04 15:30:14
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OPTIMIZATION OF GREEN SYNTHESIZED SILVER NANOPARTICLES FROM CARALLUMA UMBELLATA
摘要： Objective: The current study focuses on optimization and ecologically innocuous green synthesis of silver nanoparticles (AgNPs) using tribal plant Caralluma umbellata and to study its potential as an antibacterial and antifungal agent. Methods: The synthesis of AgNPs were confirmed by the colour change of the stem extract from yellow to dark brown and by UV-Visible spectroscopy. The optimum conditions for synthesis of AgNPs were analysed using Response surface methodology (RSM) based Box-Behnken design (BBD) using Design Expert software (7.0.0 trial version). The AgNPs synthesized were characterized by Scanning electron microscope (SEM), Energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Further, antibacterial and antifungal activity were performed using well diffusion method for both plant extract and AgNPs. Results: The UV-Visible spectrum of AgNPs revealed characteristic peak at 425.5 nm. The crystalline nature of synthesized AgNPs was confirmed by XRD with average size 26 nm. SEM confirms the spherical shape of AgNPs and by EDX the presence of elemental silver was observed. The ability of the plant to produce both reducing and capping agents were confirmed by FTIR. The optimum conditions for synthesis of AgNPs were found to be 0.55 mmol AgNO3 concentration, 45 °C temperature and 24h reaction time. Both plant sample and synthesized AgNPs exhibited good antimicrobial activity where AgNPs showed superior efficacy as an antimicrobial agent over the other. Conclusion: From the results obtained, it can be deduced that both C. umbellata stem extract and synthesized AgNPs can act as potent antimicrobial agent. But the synthesized AgNPs is more potent against bacteria and fungus.
关键词： Nanomedicine,BBD,Antimicrobial agent,Tribal plant,Silver nanoparticles
更新于2025-09-04 15:30:14
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TiO2 Nanoparticles Catalyze Oxidation of Huntingtin Exon 1-Derived Peptides Impeding Aggregation: a Quantitative NMR Study of Binding and Kinetics
摘要： Polyglutamine expansion within the N-terminal region of the huntingtin protein results in the formation of intracellular aggregates responsible for Huntington’s disease, a fatal neurodegenerative condition. The interaction between TiO2 nanoparticles and huntingtin peptides comprising the N-terminal amphiphilic domain without (httNT) or with (httNTQ10) a ten-residue C-terminal polyglutamine tract, is investigated by NMR spectroscopy. TiO2 nanoparticles decrease aggregation of httNTQ10 by catalyzing the oxidation of Met7 to a sulfoxide, resulting in an aggregation-incompetent peptide. The oxidation agent is hydrogen peroxide generated on the surface of the TiO2 nanoparticles either by UV irradiation or at low steady-state levels in the dark. The binding kinetics of non-aggregating httNT to TiO2 nanoparticles is characterized by quantitative analysis of 15N dark state exchange saturation transfer and lifetime line broadening NMR data. Binding involves a sparsely-populated intermediate that experiences hindered rotational diffusion relative to the free state. Catalysis of methionine oxidation within the N-terminal domain of the huntingtin protein may potentially provide a strategy for delaying the onset of Huntington’s disease.
关键词： Huntingtin,TiO2 nanoparticles,aggregation,NMR spectroscopy,oxidation
更新于2025-09-04 15:30:14
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Enabling the electrocatalytic fixation of N <sub/>2</sub> to NH <sub/>3</sub> by C-doped TiO <sub/>2</sub> nanoparticles under ambient conditions
摘要： The conventional Haber–Bosch process for industrial NH3 production from N2 and H2 is highly energy-intensive with a large amount of CO2 emissions and finding a more suitable method for NH3 synthesis under mild conditions is a very attractive topic. The electrocatalytic N2 reduction reaction (NRR) offers us an environmentally benign and sustainable route. In this communication, we report that C-doped TiO2 nanoparticles act as an efficient electrocatalyst for the NRR with excellent selectivity. In 0.1 M Na2SO4, it achieves an NH3 yield of 16.22 mg h?1 mgcat.?1 and a faradaic efficiency of 1.84% at ?0.7 V vs. the reversible hydrogen electrode. Furthermore, this catalyst also shows good stability during electrolysis and recycling tests.
关键词： ambient conditions,C-doped TiO2 nanoparticles,NH3 synthesis,electrocatalytic N2 reduction reaction
更新于2025-09-04 15:30:14
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Ag nanoparticle decorated MnO <sub/>2</sub> flakes as flexible SERS substrates for rhodamine 6G detection
摘要： Smart design of advanced substrates for surface-enhanced Raman scattering (SERS) activity is challenging but vital. Herein, we synthesized a new kind of AgNPs/MnO2@Al flexible substrate as a SERS substrate for the detection of the analyte rhodamine 6G (R6G). The fabrication of porous MnO2 nanoflakes on Al foil was conducted via a facile hydrothermal strategy. Owing to the large active surface area of the MnO2 nanoflakes, the Ag nanoparticles were immobilized and displayed superior SERS performance with a low detection concentration of 1 × 10?6 M for R6G. In addition, the SERS performance was found to be strongly related to the morphology of the MnO2@Al substrate material. Our smart design may provide a new method of construction for other advanced SERS substrates for the detection of R6G.
关键词： Ag nanoparticles,rhodamine 6G detection,MnO2 flakes,flexible SERS substrates
更新于2025-09-04 15:30:14