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A sandwich-configuration electrochemiluminescence immunoassay based on Cu2O@OMC-Ru nanocrystals and OMC-MoS2 nanocomposites for determination of alpha-fetoprotein.
Zhang, Z, Yu, H, Zhang, Y, Wang, Z, Gao, H, Rong, S, Meng, L, Dai, J, Pan, H, Chang, D
Mikrochimica acta. 2021;(6):213
Abstract
A sandwich-format electrochemiluminescence (ECL) immunosensor has been developed for alpha-fetoprotein (AFP) detection based on the use of ordered mesoporous carbon-molybdenum disulfide (OMC-MoS2) as a sensor platform and cuprous oxide @ ordered mesoporous carbon-Ru(bpy)32+ (Cu2O@OMC-Ru) composites as signal tags. OMC alongside MoS2 plays a synergistic role in improving the electrochemical performance of the electrode in the electron transfer process. The uniform cubic-shaped Cu2O@OMC-Ru nanocrystals display excellent luminous efficiency, with a signal amplification strategy of OMC-MoS2 synergistic enhancement and Cu2O@OMC which is capable of immobilizing more Ru(bpy)32+ serving as a tracing tag to label antibodies. A detectable ECL emission at a Cu2O@OMC-Ru nanocrystals modified electrode is initiated at an applied voltage of +1.15 V (scanning range: 0-1.2 V), in the presence of the tripropylamine (TPA) as coreactant. With the increase in AFP concentration, the loading of Cu2O@OMC-Ru at the electrode increases. Afterward, the ECL detection of AFP shows a wide linear range from 0.1 pg/mL to 10 ng/mL with a correlation coefficient of 0.9964 and a detection limit of 0.011 pg/mL (S/N = 3) under the optimal experimental conditions. The recoveries were in the range 91.2-97.1% with RSD varying from 4.8 to 8.5%. Overall, the novel immunosensor has been successfully applied to the analysis of human serum samples, indicating a great potential for application in clinical diagnostics.
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Probing the Electron Transfer between iLOV Protein and Ag Nanoparticles.
Ran, X, Zhang, Q, Zhang, Y, Chen, J, Wei, Z, He, Y, Guo, L
Molecules (Basel, Switzerland). 2020;(11)
Abstract
Nanomaterials have been widely used in biomedical sciences; however, the mechanism of interaction between nanoparticles and biomolecules is still not fully understood. In the present study, we report the interaction mechanism between differently sized Ag nanoparticles and the improved light-oxygen-voltage (iLOV) protein. The steady-state and time-resolved fluorescence results demonstrated that the fluorescence intensity and lifetime of the iLOV protein decreased upon its adsorption onto Ag nanoparticles, and this decrease was dependent upon nanoparticle size. Further, we showed that the decrease of fluorescence intensity and lifetime arose from electron transfer between iLOV and Ag nanoparticles. Moreover, through point mutation and controlled experimentation, we demonstrated for the first time that electron transfer between iLOV and Ag nanoparticles is mediated by the tryptophan residue in the iLOV protein. These results are of great importance in revealing the function of iLOV protein as it applies to biomolecular sensors, the field of nano-photonics, and the interaction mechanism between the protein and nanoparticles.
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3.
A laccase based biosensor on AuNPs-MoS2 modified glassy carbon electrode for catechol detection.
Zhang, Y, Li, X, Li, D, Wei, Q
Colloids and surfaces. B, Biointerfaces. 2020;:110683
Abstract
As a kind of two-dimensional layered nanomaterial, MoS2 nanosheets have been widely used in the field of biosensors. In this work, a novel laccase based biosensor for catechol detection was fabricated based on a nanocomposite of MoS2 nanosheets and gold nanoparticles. The experimental results demonstrated that MoS2 had large specific surface area and good biocompatibility, which provided abundant position for enzyme immobilization. Gold nanoparticles enhanced conductivity of MoS2 and improved detection sensitivity. Because of the synergistic effect of MoS2 nanosheets and gold nanoparticles, the laccase based bioelectrode exhibited a linear response to catechol from 2 to 2000 μM with a detection limit of 2 μM (S/N = 3), as well as good selectivity, stability, repeatability, and reproducibility.
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4.
DNA-templated copper nanoparticles as signalling probe for electrochemical determination of microRNA-222.
Wang, Y, Meng, W, Chen, X, Zhang, Y
Mikrochimica acta. 2019;(1):4
Abstract
An ultrasensitive electrochemical biosensor is described for the determination of microRNAs. It is based on the use of DNA-templated copper nanoparticles (Cu NPs) as signalling probe. MicroRNA-222 was selected as the model analyte. The probe was obtained from two different oligonucleotides (containing complementary bases) via hybridization chain reaction to form long DNA concatemers as template. The Cu NPs were formed by reaction of ascorbate with copper sulfate. The biosensor was fabricated as follows: (a) Capture probe (cDNA) with a thiolated group was immobilized on reduced graphene oxide modified with gold nanoparticles (rGO/Au NPs), (b) materials was placed on a glassy carbon electrode (GCE); (c) the modified electrode (cDNA/rGO/Au NPs/GCE) was sequentially hybridized with microRNA-222 and signal probe; this results in the formation of a sandwich structure of cDNA-microRNA-signal probe on surface of the modified electrode. Differential pulse voltammetry was employed to record the electrochemical response of biosensor in pH 6.0 solution. As a result, a sensitive oxidation current with a peak potential at 0.10 V (vs. SCE) was obtained corresponding to Cu NPs. The experimental conditions were optimized. Under optimal conditions, the biosensor exhibited wide linear response range (0.5 fM to 70 nM) and low limit of detection (0.03 fM; at S/N = 3). The assay possesses high selectivity and can discriminate analyte microRNA from single-base mismatched microRNA. Graphical abstractA sensitive electrochemical biosensor is described for the determination of microRNA-222 by using a dsDNA-templated Cu NPs as signalling probe. (A) represents the preparation of signal probe, and (B) represents the fabrication of electrochemical microRNA sensor.
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One-pot synthesis of acid-induced in situ aggregating theranostic gold nanoparticles with enhanced retention in tumor cells.
Cheng, M, Zhang, Y, Zhang, X, Wang, W, Yuan, Z
Biomaterials science. 2019;(5):2009-2022
Abstract
In this work, we took advantage of a one-pot reaction to prepare tumor-targeting nanoparticles (Au@T), which could respond to the intracellular acidic environment and form aggregates to enhance the retention effect of nanoparticles in tumor cells. Au@T is composed of gold nanoparticles (Au NPs) modified with 4-mercaptobenzoic acid (MCBA), p-hydroxythiophenol (HTP), LA (lipoic acid)-PEG2K-OCH3 and LA-PEG2K-biotin. During blood circulation, Au@T remains well dispersed, making it inconspicuous. Then, with the help of active targeted transport, much more Au@T becomes internalized at the tumor site. After being internalized by tumor cells, Au@T aggregates under the condition of pH = 6.0, thereby improving the retention effect of Au@T, stymieing exocytosis and reducing the amount of nanoparticles returned to the blood stream. Furthermore, the in vivo experimental results showed that aggregated Au@T exhibits excellent photothermal effects, with a tumor inhibition rate of 86.40%. The computed tomography (CT) value was found to be 1.5 times higher than that of the control group (Au@Bio), as Au@Bio was unable to aggregate in tumor cells. In conclusion, this work provides a simple method for synthesizing a type of gold nanoparticles (Au@T) with promising potential for tumor diagnosis and treatment through enhancing the retention effect in tumor cells.
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6.
Electrically controlled mass transport into microfluidic droplets from nanodroplet carriers with application in controlled nanoparticle flow synthesis.
Gu, T, Zheng, C, He, F, Zhang, Y, Khan, SA, Hatton, TA
Lab on a chip. 2018;(9):1330-1340
Abstract
Microfluidic droplets have been applied extensively as reaction vessels in a wide variety of chemical and biological applications. Typically, once the droplets are formed in a flow channel, it is a challenge to add new chemicals to the droplets for subsequent reactions in applications involving multiple processing steps. Here, we present a novel and versatile method that employs a high strength alternating electrical field to tunably transfer chemicals into microfluidic droplets using nanodroplets as chemical carriers. We show that the use of both continuous and cyclic burst square wave signals enables extremely sensitive control over the total amount of chemical added and, equally importantly, the rate of addition of the chemical from the nanodroplet carriers to the microfluidic droplets. An a priori theoretical model was developed to model the mass transport process under the convection-controlled scenario and compared with experimental results. We demonstrate an application of this method in the controlled preparation of gold nanoparticles by reducing chloroauric acid pre-loaded in microfluidic droplets with l-ascorbic acid supplied from miniemulsion nanodroplets. Under different field strengths, l-ascorbic acid is supplied in controllable quantities and addition rates, rendering the particle size and size distribution tunable. Finally, this method also enables multistep synthesis by the stepwise supply of miniemulsions containing different chemical species. We highlight this with a first report of a three-step Au-Pd core-shell nanoparticle synthesis under continuous flow conditions.
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7.
Near-infrared fluorescent ribonuclease-A-encapsulated gold nanoclusters: preparation, characterization, cancer targeting and imaging.
Kong, Y, Chen, J, Gao, F, Brydson, R, Johnson, B, Heath, G, Zhang, Y, Wu, L, Zhou, D
Nanoscale. 2013;(3):1009-17
Abstract
Ultra-small gold nanoclusters (AuNCs) have unique size-dependent optical, electrical and chemical properties. They have emerged as a new nanomaterial with broad applications in optoelectronics, catalysis, biosensing, and bioimaging. Several strategies have been exploited to prepare AuNCs of different "magic number" sizes, using different templates e.g. dendrimers, polyethyleneimines, peptides, and more recently, proteins. Notwithstanding, almost all bio-template-protected AuNCs reported so far exhibit fairly low fluorescence quantum yields (QYs), typically <5%, which is especially true for AuNCs prepared using the protein templates. In this paper, we report a facile, one-pot aqueous synthesis of highly fluorescent AuNCs using bovine pancreatic ribonuclease A (RNase-A) as the bio-template. The as-prepared AuNCs not only fluoresce strongly at the near-infrared (NIR) region (λ(em) = 682 nm), but also exhibit an elevated QY of ∼12%. Additionally, the RNase-A-encapsulated AuNC (RNase-A-AuNC) displays an exceptionally large Stokes shift of ∼210 nm as well as a single dominant fluorescence lifetime of ∼1.5 μs, about three orders of magnitude longer than biological autofluorescence. Furthermore, by coupling vitamin B(12) (VB(12)) to the RNase-A-AuNC, we develop a multifunctional nanoplatform that is suitable for simultaneous targeting and imaging of cancer at the cellular level using Caco-2 cell lines as an in vitro model. Since VB(12) has effective uptake pathways in the digestive system, this nanoplatform may have potential for targeted oral drug delivery in vivo.