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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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Quenched Sandwich-type Photoelectrochemical Aptasensor forProtein Detection based on Exciton Energy Transfer
摘要： This work proposes a quenched photoelectrochemical sensing method for highly selective and sensitive detection of protein via Energy Transfer (ET) effect between the AuNPs and CdS:Mn quantum dots. This detection was performed on a sandwich-type aptamer sensing interface. Chitosan modified CdS:Mn/TiO2/ITO electrode was used to immobilize capture DNA (S1) via -CONH- bond. In the presence of target protein, AuNPs labeled DNA (AuNPs-S2) was further bonded to the protein to fabricate sandwich sensing platform, which forced the AuNPs away from the electrode surface. In this state, the photocurrent was greatly depressed, mainly due to two factors: (a) the ET effect produced by interparticle distance between CdS:Mn and AuNPs; (b) the steric hindrance of AuNPs-S2 partly obstructs the diffusion of the electron donor. The photocurrent decreased with the increasing concentration of the target protein. Using thrombin as a target, this sensitized method showed a detectable range of 0.1 pM to 8 nM and a detection limit of 30 fM. It possessed high selectivity and good stability for detection of thrombin. This method is extremely flexible and can be extended to varieties of protein targets.
关键词： CdS:Mn,Photoelectrochemical aptasensor,Thrombin,Energy transfer,AuNPs
更新于2025-11-14 15:15:56
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One-step synthesis of hierarchical AuNPs/Cd0.5Zn0.5S nanoarchitectures and their application as an efficient photocatalyst for hydrogen production
摘要： The hierarchical AuNPs/Cd0.5Zn0.5S hybrids are directly fabricated via a facile one-step in-situ hydrothermal method. The as-prepared AuNPs/Cd0.5Zn0.5S hybrids demonstrate superior photocatalytic performance toward hydrogen production under visible light irradiation. The hydrogen evolution rate of the 5 wt% AuNPs/Cd0.5Zn0.5S synthesized with in-situ hydrothermal method can be 7.1 times greater than that of pure Cd0.5Zn0.5S and as much as 2.5 times of 5 wt% AuNPs loaded Cd0.5Zn0.5S synthesized with photodeposition method. Systematical investigations reveal that the enhanced photocatalytic performance of the one-step in-situ prepared AuNPs/Zn0.5Cd0.5S can be attributed to the inherent SPR effect and favorable electron transfer properties of AuNPs, as well as the rational hierarchical nanoarchitectures that allow AuNPs to be uniformly incorporated into Zn0.5Cd0.5S matrix. This one-step in-situ fabrication method provides a simple and efficient route to synthesize well-defined heterocatalysts.
关键词： AuNPs/Cd0.5Zn0.5S,Photocatalysis,Hydrogen evolution,SPR,One-step
更新于2025-09-23 15:22:29
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Formation of the AuNPs GO@MoS2/AuNPs Nanostructures for the SERS Application
摘要： GO nanomeshes and GO@MoS2/AuNPs nanostructures are formed on the flexible 3D Ni foam substrate for the SERS application. Smaller and denser AuNPs “hot spots” are spin-coated on such mesh-like GO@MoS2/AuNPs nanostructures to form AuNPs/GO@MoS2/AuNPs SERS substrates. The branches of GO nanomeshes are used as the homogeneous nanogaps to form the separated denser “hot spots” and absorb the molecules, resulting high electromagnetic (confirmed by the FDTD simulation) and signals enhancement. As low as 10-14 M of the Crystal Violet (CV) and Rhodamine 6G (R6G) are detected. Such flexible foam-like substrate can be used for the in-situ detection on the fish surface by scraping. DNA without label can also be easily detected by spin-coating the mixed AuNPs-DNA solution in our experiment.
关键词： AuNPs GO@MoS2/AuNPs；hybrid nanostructures；homogeneous nanogaps；SERS
更新于2025-09-23 15:21:21
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Passive Sampling of Gaseous Elemental Mercury Based on a Composite TiO2NP/AuNP Layer
摘要： Passive sampling systems (PASs) are a low cost strategy to quantify Hg levels in air over both different environmental locations and time periods of few hours to weeks/months. For this reason, novel nanostructured materials have been designed and developed. They consist of an adsorbent layer made of titania nanoparticles (TiO2NPs, ≤25 nm diameter) ?nely decorated with gold nanoparticles. The TiO2NPs functionalization occurred for the photocatalytic properties of titania-anatase when UV-irradiated in an aqueous solution containing HAuCl4. The resulting nanostructured suspension was deposited by drop-casting on a thin quartz slices, dried and then incorporated into a common axial sampler to be investigated as a potential PAS device. The morphological characteristics of the sample were studied by High-Resolution Transmission Electron Microscopy, Atomic Force Microscopy, and Optical Microscopy. UV-Vis spectra showed a blue shift of the membrane when exposed to Hg0 vapors. The adsorbed mercury was thermally desorbed for a few minutes, and then quanti?ed by a mercury vapor analyzer. Such a sampling system reported an ef?ciency of adsorption that was equal to ≈95%. Temperature and relative humidity only mildly affected the membrane performances. These structures seem to be promising candidates for mercury samplers, due to both the strong af?nity of gold with Hg, and the wide adsorbing surface.
关键词： TiO2NPs,PAS device,mercury vapors adsorbing layer,AuNPs,photocatalysis
更新于2025-09-23 15:21:01
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Decoration of porous silicon with gold nanoparticles via layer-by-layer nano-assembly for interferometric and hybrid photonic/plasmonic (bio)sensing
摘要： Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bio-applications (e.g. biosensing, drug delivery, photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nano-assembling of a positively charged polyelectrolyte, namely polyallylamine hydrochloride (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Perot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, using NaCl aqueous solutions to infiltrate the pores (roughly 4.5-fold), in the former, and unspecific bovine serum albumin (BSA) adsorption on the pore surface (roughly 2.6-fold), in the latter. Sensitivity enhancing is also confirmed for affinity and selective biosensing of streptavidin (roughly 2.5-fold) using a biotinylated polymer, namely, negatively-charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Indeed, both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk refractive index (using 35% glucose aqueous solutions) and BSA unspecific adsorption. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nano-assembly on PSi for i) the enhancing of the interferometric performance in (bio)sensing applications and ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications.
关键词： Layer-by-Layer (LbL) nano-assembly,Porous Silicon (PSi),Biosensor,Interferometer,Gold nanoparticles (AuNPs),Hybrid Photonic/Plasmonic,Distribute Bragg Reflector (DBR),Sensor
更新于2025-09-23 15:19:57
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Portable and benchtop Raman spectrometers coupled to cluster analysis to identify quinine sulfate polymorphs in solid dosage forms and antimalarial drug quantification in solution by AuNPs-SERS with MCR-ALS
摘要： This paper proposes for the first time: (a) a qualitative analytical method based on portable and benchtop backscattering Raman spectrometers coupled to hierarchical cluster analysis (HCA) and multivariate curve resolution – alternating least-squares (MCR-ALS) to identify two polymorphs of antimalarial quinine sulfate in commercial pharmaceutical tablets in their intact forms and (b) a quantitative analytical method based on gold nanoparticles (AuNPs) as active substrates for surface-enhanced Raman scattering (SERS) in combination with MCR-ALS to quantify quinine sulfate in commercial pharmaceutical tablets in solution. The pure concentration and spectral profiles recovered by MCR-ALS proved that both formulation present different polymorphs. These results also were confirmed by two clusters observed in HCA model, according to their similarities within and among the samples that provided useful information about homogeneity of different pharmaceutical manufacturing processes. AuNPs-SERS coupled to MCR-ALS was able to quantify quinine sulfate in the calibration range from 150.00 to 200.00 ng mL-1 even with strong overlapping spectral profile of background SERS signal, proving that is a powerful ultrahigh sensitivity analytical method. This reduced linearity was validated through a large calibration range from 25.00 to 175.00 μg mL-1 used in a reference analytical method based on high performance liquid chromatography with diode array detector (HPLC-DAD) coupled to MCR-ALS for analytical validation purposes even in the presence of coeluted compound. The analytical methods herein developed are fast, because second-order chromatographic data and first-order SERS spectroscopic data where obtained in less than 6 and 2 min, respectively. Concentrations of quinine sulfate were estimated with a low root mean square error of prediction (RMSEP) values and a low relative error of prediction (REP%) in the range 1.8-6.1%.
关键词： Quinine sulfate pharmaceutical tablets,Raman spectrometer,polymorphs,HCA and MCR-ALS,AuNPs-SERS
更新于2025-09-23 15:19:57
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A fluorometric aptasensor for bisphenol a based on the inner filter effect of gold nanoparticles on the fluorescence of nitrogen-doped carbon dots
摘要： An aptamer-based fluorometric assay is described for the determination of bisphenol A (BPA). The aptamer against BPA is first attached to the surface of the red AuNPs, and this prevents the AuNPs from salt-induced formation of a blue-colored aggregate. Hence, the blue fluorescence of added nitrogen-doped carbon dots (NCDots) is quenched via an inner filter effect (IFE) caused by the red AuNPs. After addition of BPA, the BPA/aptamer complex is formed, and the AuNPs are no longer stabilized agains aggregation. This weakens the IFE and results in the recovery of the fluorescence of the NCDots which is measured best at excitation/emission wavelengths of 300/420 nm. The recovered fluorescence increases linearly in the 10 to 250 nM and 250 to 900 nM BPA concentration ranges, and the detection limit is 3.3 nM. The method was successfully applied to the determination of BPA in spiked environmental tap water samples.
关键词： Wide linear range,Quick response,Salt-induced aggregation,Tap water,Low detection limit,BPA/aptamer complexes,Aggregated AuNPs,Environmental-friendly,Fluorescence quenched,Fluorescence recovery
更新于2025-09-23 15:19:57
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AIP Conference Proceedings [AIP Publishing TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - Athens, Greece (4–6 September 2019)] TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - Time effect on the red shift of surface plasmonic resonance core-shell SiO2: Gold nanoparticles (AuNPs)
摘要： Spherical gold nanoparticles (AuNPs) chemically synthesized by Turkevich method, it coated with sodium silicate stock solution (Na2SiO3). Study different rate effect (SiO2 and ethanol) on position of surface plasmon resonance (SPR) of gold nanoparticles (AuNPs) after coated by using UV–Vis absorption spectroscopy. UV–vis spectrum showed that rate (SiO2 and ethanol) had effect in the coated gold nanoparticles (AuNPs), that Peak band gold nanoparticles (AuNPs) uncoated at (515nm) and this peak was shifted to longer wavelength (518nm) after coating. Coated after get a little shift in position of surface plasmon resonance (SPR) this means that coated method has an important role in maintain on gold nanoparticles (AuNPs) stability.
关键词： gold nanoparticles (AuNPs),Surface Plasmon Resonance (SPR),Sodium Silicate (Na2SiO3),Turkevich method
更新于2025-09-16 10:30:52