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Activated Plasmonic Nanoaggregates for Dark-Field in Situ Imaging for HER2 Protein Imaging on Cell Surfaces
摘要： Dark-?eld microscopy (DFM) based on localized surface plasmon resonance (LSPR) was used for observation of experimental phenomena, which is a hopeful nondamaging and non-photobleaching biological imaging technique. In this strategy, plasma nanoaggregates with stronger scattering e?ciency were formed in the presence of the target, causing a “turn-on” phenomenon, when asymmetry modi?ed AuNPs were introduced as probes with zero LSPR background. First, ?CC probe were designed for the cycloaddition between azide and alkyne Au1 to form AuNP dimers under catalytic action by Cu+, which was obtained from the reduction of Cu2+ by sodium ascorbate. The two kinds of probes were successfully used for the detection of Cu2+ in rat serum. Then, to apply this concept to protein on cells, DNA and antibody were modi?ed on the ?CC probe were proposed for HER2 protein DFM on cells. By designing an aptamer sequence in primer, the rolling circle ampli?cation (RCA) was introduced in HER2 DFM on cells, and the image signal was much brighter than that from no-RCA. The unique design made it easier to discriminate the target signal from background noise in cell DFM. This method might be used in the ?elds of molecular diagnostics and cell imaging.
关键词： click chemistry,rolling circle ampli?cation,localized surface plasmon resonance,AuNPs,HER2 protein,Dark-?eld microscopy
更新于2025-09-16 10:30:52
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Sandwich-type Surface Stress Biosensor Based on Self-Assembled Gold Nanoparticles in PDMS Film for BSA Detection
摘要： Polydimethylsiloxane (PDMS) films compositing with gold nanomaterials have drawn increasing interest for their application in biosensors. However, gold and PDMS exhibit poor compatibility, limiting their sensitivity in biosensing. Herein, we reported a surface stress biosensor based on a gold nanoparticle–PDMS (AuNP–PDMS) composite film to detect bovine serum albumin (BSA). The AuNP–PDMS film was fabricated by in-situ reduction of PDMS and further reduction of glucose. The compatibility between gold and PDMS was improved via two-step reduction of AuNPs. The surface stress biosensor can specifically detect BSA molecules within 0–50 μg/mL concentration range by using the direct assay and the sandwich assay. The sandwich assay amplified the surface stress and reduced the limit of detection to 0.035 μg/mL, which is lower than that achieved by the direct assay. The sandwich-type biosensor also exhibits stability, repeatability and specificity. This study is expected to drive the development of new methods for biomolecule detection.
关键词： surface stress biosensor,BSA detection,self-assembly AuNPs,sandwich assay
更新于2025-09-11 14:15:04
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Electrochemical Detection of 4-p-nitrophenol Based on TiO2NPs / RGO / AuNPs Composite Modified Glassy Carbon Electrode
摘要： A glassy carbon electrode modified with TiO2NPs/RGO/AuNPs was used as an electrochemical sensor to detect trace amounts of 4-p-nitrophenol (4-NP). The surface morphology of the composites was characterized by field-emission scanning electron microscopy (FE-SEM). The electrochemical characteristics of the composite electrode were analyzed by cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The modified electrode exhibited outstanding electrochemical performance due to the large specific surface area and strong conductivity of composite material. The differential pulse voltammetry(DPV) and square wave voltammetry(SWV) were used for the trace detection of p-nitrophenol. The peak current of the two methods showed a high linear relationship with the 4-NP concentration. The detection range applied DPV method was 0.5-100μmol/L, the detection limit was 0.03μmol/L. When SWV was employed, detection range was from 0.5 to 100μmol/L, The detection limit was 0.08μmol/L. In this study, the electrochemical sensor had the advantage of large detection range, low detection limit, stable, simple and fast analysis. Based on these characteristics, the sensor can be considered as a potential sensor for the detection of 4-NP.
关键词： 4-NP,Square Wave Voltammetry,TiO2NPs,AuNPs,RGO,Differential Pulse Voltammetry
更新于2025-09-11 14:15:04
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A Novel Fluorescence Switch for MicroRNA Imaging in Living Cells based on DNAzyme Amplification Strategy.
摘要： MicroRNAs (miRNAs) play important roles in the regulation of target gene expression and cell development. Therefore, developing of accurate and visual detection methods for miRNAs is important for early diagnosis of cancer. In this study, we established a visual detection method for miRNA 155 based on DNAzyme amplification strategy in living cells. MnO2 nanosheets were employed to deliver Locked DNAzyme and Substrate DNA into cells. AuNPs-Probe were taken up by cells autonomously. Then, MnO2 nanosheets were reduced to Mn2+ by glutathione (GSH) in cells and DNA modules were released. MiRNA 155 took away Locker DNA by strand displacement reaction to activate the DNAzyme. Then the DNAzyme cleaved substrate DNA and released single-stranded DNA named Key DNA. Key DNA opened the hairpin DNA that modified on gold nanoparticles (AuNPs) and turn on the fluorescence of cy5. One target miRNA led to plenty of released Key DNA when lots of substrate DNA were added. Thus, the visual detection of miRNA 155 in living cells would be initiated. Under confocal laser microscopy, the fluorescence was obviously observed in tumor cells but not in normal cells. The method has a linear range from 0.1 nM to 10 nM and a low detection limit of 44 pM in vitro detection.
关键词： DNA walker,microRNA,AuNPs,Fluorescence imaging,MnO2,DNAzyme,Signal amplification
更新于2025-09-09 09:28:46
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Irradiation Effects on Polymer-Grafted Gold Nanoparticles for Cancer Therapy
摘要： In the context of cancer treatment, gold nanoparticles (AuNPs) are considered as very promising radiosensitizers. Here, well-defined polymer-grafted AuNPs were synthesized and studied under gamma irradiation to better understand the involved radiosensitizing mechanisms. First, various water-soluble and well-defined thiol-functionalized homopolymers and copolymers were obtained through Atom Transfer Radical Polymerization. They were then used as ligands in the one-step synthesis of AuNPs, resulting in stable hybrid metal-polymer nanoparticles. Second, these nano-objects were irradiated in solution by gamma rays at different doses. Structures were fully characterized through SEC, SAXS and SANS measurements, prior and after irradiation. We were thus able to quantify and to localize radiation impacts onto the grafted polymers, revealing the production sites of reactive species around AuNPs. Both external and near-surface scissions were observed. Interestingly, the ratio between these two effects was found to vary according to the nature of polymer ligands. Medium-range and long-distance dose enhancements could not be identified from the calculated scission yields, but several mechanisms were considered to explain high yields found for near-surface scissions. Then, cytotoxicity was shown to be equivalent for both non-irradiated and irradiated polymer-grafted NPs, suggesting that released polymer fragments were non-toxic. Finally, the potential to add bioactive molecules such as anticancer drugs has been explored by grafting doxorubicin (DOX) onto the polymer corona. This may lead to nano-objects combining both radiosensitization and chemotherapy effects. This work is the first one to study in details the impact of radiation on radiosensitizing nano-objects combining physical, chemical and biological analyses.
关键词： irradiation,Polymer-grafted AuNPs,radiosensitization,doxorubicin,cytotoxicity,SAXS,SANS
更新于2025-09-09 09:28:46
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Enhanced Electrocatalysis via Boosted Separation of Hot Charge Carriers of Plasmonic Gold Nanoparticles Deposited on Reduced Graphene Oxide
摘要： The plasmon enhancement on electrocatalysis was investigated on pure Au nanoparticles (AuNPs) and AuNPs-reduced graphene oxide (AuNPs/rGO) hybrid. Upon Localized surface plasmon resonance (LSPR) excitation, hot charge carriers (hot electrons and holes) generate on AuNPs. In the experiments, hot holes are scavenged by glucose, and hot electrons could be efficiently transferred to the external electric circuit under a potential bias, resulting in an observable current enhancement. Then the hot electrons transfer efficiency can be quantitatively compared by the increased current response. It was found that the current density increases more obviously on AuNPs/rGO hybrid compared to pure AuNPs upon light irradiation. Due to the excellent electron mobility of rGO and perfect electron affinity capacity, the hot electrons generated on AuNPs will be efficiently transferred to the closely contacted rGO, then flow into the external circuit generating current. The present study highlights the role of rGO in improving the separation of hot charge carriers to promote the photocatalysis reactions.
关键词： Au nanoparticles (AuNPs),Hot charge carriers,Localized surface plasmon resonance (LSPR),Graphene,Electrochemical method
更新于2025-09-04 15:30:14