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An Overview of the Synthesis of Gold Nanoparticles Using Radiation Technologies
摘要： At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.
关键词： electron beam radiation,radiation technologies,X-ray,radiolytic synthesis,gamma radiation,gold nanoparticle
更新于2025-09-09 09:28:46
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Linear Optical Properties of Gold Colloid
摘要： Gold colloid was prepared by reducing HAuCl4·4H2O with Na3C6H5O7·2H2O. The morphology, size of gold nanoparticles and the optical property of colloid were characterized by transmission electron microscope and UV-Vis spectrophotometer, respectively. It shows that the gold nanoparticles are in the shape of spheres with diameters less than 8 nm, and the surface plasmon resonance absorption peak is located at about 438 nm. As the volume fraction of gold particles increases, the intensity of absorption peak strengthens. The optical property of gold colloid was analyzed by Maxwell-Garnett (MG) effective medium theory in the company of Drude dispersion model. The results show that the matrix dielectric constant is a main factor, which influences the optical property of gold colloid.
关键词： gold nanoparticle,aqueous-phase reduction,Maxwell-Garnett effective medium theory,Drude dispersion model
更新于2025-09-09 09:28:46
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Logic Sensing of MicroRNA in Living Cells Using DNA-Programmed Nanoparticle Network with High Signal Gain
摘要： Molecular circuits capable of implementing Boolean logic in cellular environments have emerged as an important tool for in situ sensing, elucidating, and modulating cell functions. The performance of existing molecular computation devices in living cells is limited because of the low level of biomolecular inputs and moderate signal gain. Herein, we devised a new class of DNA-programmed nanoparticle network with integrated molecular computation and signal amplification functions for logic sensing of dual microRNA (miRNA) molecules in living cells. The nanoparticle network, which is composed of DNA-bridged gold nanoparticles and quantum dots (QDs), could simultaneously interface with two miRNA molecules, amplify the molecular inputs, perform a calculation through AND logic gate, and generate QD photoluminescence (PL) as an output signal. Significant improvement in imaging sensitivity is achieved by integrating the signal amplifier into the molecular computation device. It allows discrimination of specific cancer cell type via intelligent sensing of miRNA patterns in living cells.
关键词： assembly,microRNA,DNA,cancer imaging,gold nanoparticle,logic gate,quantum dot
更新于2025-09-09 09:28:46
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Direct Synthesis of Gold Nanoparticle‐Over‐Nanosheet for Sensitive SERS Detection
摘要： A simple ethanol sol-based method for the synthesis of gold nanosheets (AuNSs) and gold nanoparticle-over-nanosheet (AuNP/NS) is developed. Gold nanoparticles (AuNPs) with average sizes of ≈8 nm are grown in situ on the surface of the AuNS, which forms a NP/NS structure that obtains strong, significantly improved, surface-enhanced Raman spectroscopy activity with the magnitude ≈2 and ≈6 orders higher than the simplex AuNP and AuNS, respectively. This performance is mainly attributed to uniform AuNPs that are closely packed over AuNS and coupled with NP–NS and NP–NP interactions. The NP–NS–GP (the gap between NP–NS) is narrower than NP–NP–GP in which much stronger and steadier plasmon resonance is obtained that can significantly enhance the Raman signal. The results show that single-crystalline AuNS is an ideal substrate, which can be further coated with other metallic NPs to form a new flexible, high-activity and AuNS-based nanocomposite for a wide variety of applications.
关键词： gold nanoparticle-over-nanosheet (AuNP/NS) composite,2D gold nanosheet (AuNS),surface-enhanced Raman spectroscopy (SERS)
更新于2025-09-04 15:30:14
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Multivalent Biopolymer Capped Gold Nanoparticles as Stable and Non-Specific Endocytosis-Free Cell Labeling Agents
摘要： In this study, we report that carboxymethyl cellulose (CMC) is a stable capping agent for cellular labeling with gold nanoparticles (AuNPs). AuNPs were easily capped with CMC by simply mixing them and removing any unbound CMC by centrifugation. The CMC-capped AuNPs showed high stability in the presence of up to 100 mM of NaCl and (cid:1)-mercaptoethanol. Structural analysis of CMC-capped AuNPs revealed that multiple binding of CMC on AuNPs resulted in the stable protection. For specific cell labeling, anti-CD44 antibody was conjugated to CMC-capped AuNPs. Cellular labeling performance of the antibody-conjugated AuNPs was verified by adding these nanoparticles to HeLa cell containing culture. We observed light scattering spots from AuNPs inside HeLa cells, which were incubated with the antibody-conjugated AuNPs without non-specific endocytosis. However, clusters of citrate-capped AuNPs were found to be entrapped inside the cells through receptor-mediated endocytosis. In addition, no cytotoxicity was observed, confirming that CMC-capped AuNPs are useful as stable and biocompatible cell-labeling agents.
关键词： Endocytosis,Gold Nanoparticle,Darkfield,Carboxymethyl Cellulose,Cancer,Cellular Labeling Agent,CD44
更新于2025-09-04 15:30:14
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Reduced graphene oxide decorated with gold nanoparticle as signal amplification element on ultra-sensitive electrochemiluminescence determination of caspase-3 activity and apoptosis using peptide based biosensor
摘要： Introduction: Growing demands for ultrasensitive biosensing have led to the development of numerous signal amplification strategies. In this report, a novel electrochemiluminescence (ECL) method was developed for the detection and determination of caspase-3 activity based on reduced graphene oxide sheets decorated by gold nanoparticles as signal amplification element and horseradish peroxidase enzyme (HRP) as ECL intensity enhancing agent. Methods: The ECL intensity of the luminol was improved by using the streptavidin coated magnetic beads and HRP in the presence of hydrogen peroxide. The cleavage behavior of caspase-3 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using biotinylated peptide (DEVD containing peptide) which was coated on reduced graphene oxide decorated with gold nanoparticle. The surface modification of graphene oxide was successfully confirmed by FTIR, UV-vis and x-ray spectroscopy. Results: ECL based biosensor showed that the linear dynamic range (LDR) and the lower limit of quantification (LLOQ) were 0.5-100 and 0.5 femtomolar (fM), respectively. Finally, the performance of the engineered peptide based biosensor was validated in the A549 cell line as real samples. Conclusion: The prepared peptide based biosensor could be considered as an excellent candidate for early detection of apoptosis, cell turnover, and cancer related diseases.
关键词： DEVD-peptide,Electrochemiluminescence,Apoptosis,Reduced graphene oxide,Caspase-3,Gold nanoparticle
更新于2025-09-04 15:30:14