Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

Ultrasmall gold nanoparticles(AuNPs)typically includes atomically precise gold nanoclusters(AuNCs)and AuNPs with a core size below 3 nm.Serving as a bridge between small molecules and traditional inorganic nanoparticles,the ultrasmall AuNPs show the unique advantages of both small molecules(e.g.,rapid distribution,renal clearance,low non-specific organ accumulation)and nanoparticles(e.g.,long blood circulation and enhanced permeability and retention effect).The emergence of ultrasmall AuNPs creates significant opportunities to address many challenges in the health field including disease diagnosis,monitoring and treatment.Since the nano–bio interaction dictates the overall biological applications of the ultrasmall AuNPs,this review elucidates the recent advances in the biological interactions and imaging of ultrasmall AuNPs.We begin with the introduction of the factors that influence the cellular interactions of ultrasmall AuNPs.We then discuss the organ interactions,especially focus on the interactions of the liver and kidneys.We further present the recent advances in the tumor interactions of ultrasmall AuNPs.In addition,the imaging performance of the ultrasmall AuNPs is summarized and discussed.Finally,we summarize this review and provide some perspective on the future research direction of the ultrasmall AuNPs,aiming to accelerate their clinical translation.

Applications and safety of gold nanoparticles as therapeutic devices in clinical trials

Use of gold nanoparticles(GNPs)in medicine is an emerging field of translational research with vast clinical implications and exciting therapeutic potential.However,the safety of using GNPs in human subjects is an important question that remains unanswered.This study reviews over 20 clinical trials focused on GNP safety and aims to summarize all the clinical studies,completed and ongoing,to identify whether GNPs are safe to use in humans as a therapeutic platform.In these studies,GNPs were implemented as drug delivery devices,for photothermal therapy,and utilized for their intrinsic therapeutic effects by various routes of delivery.These studies revealed no major safety concerns with the use of GNPs;however,the number of trials and total patient number remains limited.Multi-dose,multicenter blinded trials are required to deepen our understanding of the use of GNPs in clinical settings to facilitate translation of this novel,multifaceted therapeutic device.Expanding clinical trials will require collaboration between clinicians,scientists,and biotechnology companies.

Molecular fluorescence significantly enhanced by gold nanoparticles@zeolitic imidazolate framework-8

Noble metal nanoparticles exhibit unique surface plasmon resonance dependent optical properties.On this basis,gold nanoparticles(AuNPs)encapsulated in metal–organic frameworks(MOFs)can form AuNPs@MOFs composites to modulate the optical properties of fluorescent molecules,which is less reported.In this paper,based on the fluorescence enhancement effect of AuNPs on 2-(2-hydroxyphenyl)-1H-benzimidazole(HPBI)molecules,zeolitic imidazolate framework-8(ZIF-8)crystals with structural stability were introduced.AuNPs@ZIF-8 exhibited a significantly pronounced fluorescence enhancement of the HPBI molecules.In addition,by comparing the fluorescence characteristics of the HPBI molecules adsorbed on AuNPs@ZIF-8 and those captured in AuNPs@ZIF-8,we found that the ZIF-8 can act as a spacer layer with highly effective near-field enhancement.All our preliminary results shed light on future research on the composite structures of noble metal particles and MOFs for fluorescent probes and sensing applications.

Theoretical investigation of F-P cavity mode manipulation by single gold nanoparticles

The ability to manipulate microlaser is highly desirable towards high-performance optoelectronic devices.Here we demonstrate feasible mode manipulation of Fabry-Perot type microlasers of a perovskite nanowire via incorporation of single gold nanoparticles.The influences of resonant wavelength,quality factor and emission directions are successively investigated using a two-dimensional finite-difference time-domain method.It is found that blueshift of resonant wavelength could be achieved together with either promoted or degraded quality factor of the microlaser via single Au NPs with varied sizes.Unidirectional emission could also be realized which is favorable for on-chip integration.Our results provide useful reference for feasible manipulation of light-matter interactions and mode selection.

Effect of Gold Nanoparticles on the Photocatalytic and Photoelectrochemical Performance of Au Modified BiVO_4

An efficient visible light driven photocatalyst, gold nanoparticles(NPs) modified Bi VO_4(Au/Bi VO_4), has been synthesized by deposition-precipitation with urea method. Au/Bi VO_4 exhibits enhanced photocatalytic activity for phenol degradation underλ>400 nm irradiation but negligible activity underλ>535 nm,indicating that the surface plasmon resonance(SPR) effect is too weak for organic photodegradation. According to the photoelectrochemical results of the porous powder electrodes of Bi VO_4 and Au/Bi VO_4, the SPR effect of Au NPs has been assessed. The role of Au NPs as electron sinks or sources, which is controllable by incident photon energy and applied potentials, has been discussed.

A Concise Review of Gold Nanoparticles-Based Photo-Responsive Liposomes for Controlled Drug Delivery

The focus of drug delivery is shifting toward smart drug carriers that release the cargo in response to a change in the microenvironment due to an internal or external trigger. As the most clinically successful nanosystem, liposomes naturally come under the spotlight of this trend. This review summarizes the latest development about the design and construction of photo-responsive liposomes with gold nanoparticles for the controlled drug release. Alongside, we overview the mechanism involved in this process and the representative applications.

Fluorescence quenching method for the determination of catechol with gold nanoparticles and tyrosinase hybrid system

The determination method of catechol by fluorescence quenching was developed.The assay was based on the combination of the unique property of gold nanoparticles with tyrosinase enzymatic reaction.In the presence of tyrosinase,the fluorescence of gold nanoparticles was quenched by catechol which can be employed to detect catechol.Under the optimal conditions,a linear range 5.0×10^(-7)-1.0×10^(-3) mol L^(-1) and a detection limit 1.0×10^(-7) mol L^(-1) of catechol were obtained.o-Quinone intermediate produced...

Efficacy of Gold Nanoparticles against Nephrotoxicity Induced by Schistosoma mansoni Infection in Mice

Objective In this study, the ameliorative effects of gold nanoparticles （gold NP） on the renal tissue damage in Schistosoma mansoni （S. mansoni）-infected mice was investigated. Methods High-resolution transmission electron microscopy was used for the characterization of NP. The gold NP at concentrations of 250, 500, and 1000 μg/kg body weight were inoculated into 5. mansoni-infected mice. Results The parasite caused alterations in the histological architecture. Furthermore, it induced a significant reduction in the renal glutathione levels; however, the levels of nitric oxide and malondialdehyde were significantly elevated. The parasite also managed to downregulate KIM-I, NGAL, MCP-1, and TGF-8 mRNA expression in infected animals. Notably, gold NP treatment in mice reduced the extent of histological impairment and renal oxidative damage. Gold NP were able to regulate gene expression impaired by 5. Mansoni infection. Conclusion The curative effect of gold NP against renal toxicity in 5. mansoni-infected mice is associated with their role as free radical scavengers.

Self-organization of Gold Nanoparticles Protected by 9-(5-Thiopentyl)-carbazole

Through the reduction of [AuCl4] by aqueous sodium borohydride in the presence of 9-(5-thiopentyl)-carbazole, the gold nanoparticles has been prepared and characterized.

Inhibition of retinal angiogenesis by gold nanoparticles via inducing autophagy

AIM： To investigate the effect of gold nanoparticles on retinal angiogenesis in vitro and in vivo, and to reveal the possible mechanism.METHODS： Seed growth method was used to synthesize gold nanoparticles（GNPs）. The size, zeta potential, absorption spectrum and morphology of GNPs were identified using Malvern Nano-ZS, multimode reader（Bio Tek synergy2） and transmission electron microscope. Cell viability was analyzed using cell counting kit-8 method and cell growth was assessed with EdU kit. Transwell chamber was used to investigate cell migration. Tube formation method was used to assess the angiogenic property in vitro. Oxygen induced retinopathy（OIR） model was used to investigate the effect of GNPs on retinal angiogenesis. Confocal microscope and Western blot were used to study the possible mechanism of GNPs inhibited angiogenesis.RESULTS： The GNPs synthesized were uniform and well dispersed. GNPs of 10 μg/mL and 20 μg/mL were able to inhibit human umbilical vein endothelial cells proliferation（50% and 72% separately, P〈0.001）, migration（54% and 83% separately, P〈0.001） and tube formation（52% and 90% separately, P〈0.001）. Further data showed that GNPs were able to improve the retinopathy in an OIR model. The possible mechanism might be that GNPs were able to induce autophagy significantly（P〈0.05）.CONCLUSION： The present study suggests that GNPs are able to inhibit retinal neovascularization in vitro and in vivo. GNPs might be a potential nanomedicine for the treatment of retinal angiogenesis.

Seed-mediated growth of gold nanoparticles using self-assembled monolayer of polystyrene microspheres as nanotemplate arrays

Arrays of noble metal nanoparticles show potential applications in （bio-）sensing, optical storage, surface-enhanced spectroscopy, and waveguides. For all such potential devices, controlling the size, morphology, and interparticle spacing of the nanoparticles is very important. Here, we combine seed-mediated growth with nanosphere lithography to study the controllable growth of gold nanoparticles （Au NPs）, in which the self-assembly monolayer of polystyrene （PS） on a silicon surface is used to guide the modification of allaunesilanes and the subsequent adsorption of gold seeds; seed-mediated growth is applied to controlling the morphology and size of Au NPs. The size of adsorption region （determining the number of adsorbed gold seeds） is controlled by etching PS microspheres with oxygen plasma or annealing PS microspheres at the glass transition temperature. The size and morphology of the Au NPs are controlled by changing growth conditions. In such a way, we have achieved the dual control of the obtained Au NPs. Preliminary results show that this strategy holds a great promise. This approach can also be extended to a wide range of materials and substrates.

Visualization of gold nanoparticles formation in DC plasma-liquid systems

Dual argon plasmas ignited by one direct current power source are used to treat an aqueous solution of hydrogen tetrachloroaurate-(Ⅲ)trihydrate(HAuCl_(4)·3H_(2)O)which is contained in an H-type electrochemical cell.The solution contained in one cell acts as a cathode,and in the other as an anode.Experiments are carried out to directly visualize the formation process of gold nanoparticles(Au NPs)in separated cells of the H-type electrochemical reactor.The results and analyzes suggest that hydrogen peroxide and hydrated electrons generated from the plasma-liquid interactions play the roles of reductants in the solutions,respectively.Hydrogen peroxide can be generated in the case of the liquid being a cathode or an anode,while most of hydrated electrons are formed in the case of the liquid being an anode.Therefore,the reduction of the AuCl_(4)−ions is mostly attributed to the hydrogen peroxide as the liquid acts as a cathode,while to the hydrogen peroxide and hydrated electrons as the liquid acts as an anode.Moreover,the p H value of the solution can be used to tune the formation processes and final form of the Au NPs due to its mediation of reductants.

Optical manipulation of gold nanoparticles using an optical nanofiber

Gold nanoparticles are gaining increasing attention due to their biological and medical applications.In this letter,we experimentally demonstrate the optical manipulation of 250-nm-diameter gold nanoparticles along an optical nanofiber（550 nm in diameter） injected by an 808-nm laser light.The nanoparticles situated in the evanescent optical field are trapped by optical gradient force and move along the direction of light propagation due to optical scattering force.The velocities reach as high as 132 μm/s at an optical power of 80 mW.

Synthesis and microwave absorption properties of graphene-oxide(GO)/polyaniline nanocomposite with gold nanoparticles

A composite of graphene/PANI/GAunano is synthesized using the co-blend method. The morphologies and microstructures of samples are examined by transition electron microscopy(TEM) and Fourier transform infrared spectroscopy(FTIR). Moreover, the microwave absorption properties of both graphene/PANI and GO/PANI/ GAunano composites are investigated in a microwave frequency band from 1 GHz to 18 GHz. The maximum reflection loss(RL) of GO/PANI/GAunano with a thickness of 2 mm is up to-24.61 d B at 15.45 GHz, and the bandwidth corresponding to RL at-10 d B can reach 4.08 GHz(from 13.92 GHz to 18.00 GHz) for a 2-mm-thick layer. The electromagnetic data demonstrate that GO/PANI/GAunano can be used as an attractive candidate for microwave absorbers.

Synthesis of silver and gold nanoparticles from leaf of Litchi chinensis and its biological activities

Objective: To synthesize and isolate silver and gold nanoparticles from Litchi chinensis leaf methanolic extract, and to evaluate its comparative biological activities including muscles relaxant, analgesic, anti-inflammatory and antidiarrheal. Methods: The gold and silver nanoparticles were synthesized by dissolving methanolic extract in gold chloride and silver nitrate solution separately which were confirmed by colour change and UV-Vis spectroscopy, and pellets were collected through centrifugation. Biological activities of the extract were conducted on BALB/c mice through various standard methods and the data were subjected to One-way ANOVA. Results: The colorless gold chloride solution changed to purple soon after the addition of plant extract, demonstrating that the reaction took place and gold ions were reduced to gold nanoparticles, while colorless silver nitrate solution changed to light and dark brown that was indicative of silver nanoparticles. The muscles relaxant activity showed that silver nanoparticles were more effective than gold nanoparticles and methanolic extract in traction test. The analgesic activity showed that silver and gold nanoparticles showed highest percentage decrease in acetic acid induced writhing at the doses of 50, 100 and 150 mg/kg b.w. The highest anti-inflammatory activity was produced by gold nanoparticles followed by silver nanoparticles, while low activity was observed in methanolic leaf extract. Only the crude methanolic extract showed significant antidiarrheal activity as compared to the standard drug atropine sulphate, while antidiarrheal activities of gold and silver nanoparticles were non-significant. Conclusions: The present work concludes that isolated silver and gold nanoparticles from leaf methanolic extract shows strong muscles relaxant, analgesic and anti-inflammatory activities while crude methanolic extract possesses good antidiarrheal activity.

Breast cancer therapy by laser-induced Coulomb explosion of gold nanoparticles

Objective： Laser-induced Coulomb explosion of gold nanoparticles for breast cancer has been studied by nanophotolysis technique. This study aimed to investigate whether laser-induced bubble formation due to Coulomb explosion can provide an effective approach for selective damage of breast cancer with gold nanoparticles. Method： Numerical method involves laser-induced Coulomb explosion of gold nanoparticles. Different parameters related to nanophotolysis such as laser fluence, tumor depth, cluster radius, laser pulse duration, and bubble formation is studied numerically. Numerical simulation was performed using Mat lab. Results： The gold nanopartieles of 10, 20, 30, 40, and 50 nm in radius could penetrate into tumor 1.14, 1.155, 1.189, 1.20 and 1.22 cm in depth respectively. The maximum penetration depth in tumor could be obtained with nanoparticles of 50 nm radius. Short laser pulse of 40 ns with nanoparticles of 10 nm radius could penetrate into tumor 1.14 cm in depth. Bubbles with a radius of 9 pm could effectively kill breast cancer cells without damaging healthy ones. The bubble radius increased from 4 to 9 lam with an increase in pulse duration in the range of 10 to 30 ns. Conclusions： Gold nanoparticles with increasing radius and bubble formation for selective damage of breast cancer cells are successfully probed. The present calculated results are compared with other experimental findings, and good correlation is found between the present work and previous experimental values. It was demonstrated that bubble formation in tumor may further increase the efficacy of breast cancer treatment.

Sputtered gold nanoparticles enhanced quantum dot light-emitting diodes

Surface plasmonic effects of metallic particles have been known to be an effective method to improve the perfor- mances of light emitting didoes. In this work, we report the sputtered Au nanoparticles enhanced electroluminescence in inverted quantum dot light emitting diodes （ITO/Au NPs/ZnMgO/QDs/TFB/PEDOT：PSS/A1）. By combining the time- resolved photoluminescence, transient electroluminescence, and ultraviolet photoelectron spectrometer measurements, the enhancement of the internal field enhanced exciton coupling to surface plasmons and the electron injection rate increasing with Au nanoparticles＇ incorporation can be explained. Phenomenological numerical calculations indicate that the electron mobility of the electron transport layer increases from 1.39 ×10-5 cm2/V-s to 1.91 ×10-5 cm2/V-s for Au NPs modified device. As a result, the maximum device luminescence is enhanced by 1.41 fold （from 14600 cd/cm2 to 20720 cd/cm2） and maximum current efficiency is improved by 1.29 fold （from 3.12 cd/A to 4.02 cd/A）.

Surface-ligand effect on radiosensitization of ultrasmall luminescent gold nanoparticles

Gold nanoparticles(AuNPs)could serve as pot ential radiother apy sensitizers because of their exceptional biocompatibility and high.Z material nature;however,since in vitro and in vivo behaviors of AuNPs are determined not only by their particle size but also by their surface chemistries,whether surface ligands can affect their radiosensitization has seldom been investi-gated in the radiosensitization of AuNPs.By conducting head-to-head comparison on radio-sensitization of two kinds of ultrasmall(~2 nm)near-infrared(NIR)emitting AuNPs that are coated with zwitterionic glutathione and neutr al polyethylene glyol(PEG)ligands,respectively,we found that zwitterionic glut athione coated AuNPs(GS-AuNPs)can reduce survival rates of MCF-7 cells under irr adiation of clinically used megavoltage photon beam at low dosage of~2.25 Gy.On the other hand,PEG-AuNPs can serve as a radiation-protecting agent and enabled MCF-7 cells more resistant to the irradiation,clearly indicating the key role of surface cheistry in radiosensitization of AuNPs.More detailed studies suggested that such difference was inde-pendent of cellular uptake and its eficiency,but might be related to the ligand-induced difference in photoelectron generation and/or inter actions between AuNPs and X-ray triggered reactive oxygen species(ROS).

Identification of SARS-CoV-2 by gold nanoparticles

The SARS-CoV-2 outbreaks highlighted the need for effective,reliable,fast,easy-to-do and cheap diagnostics procedures.We pragmatically experienced that an early positive-case detection,inevitably coupled with a mass vaccination campaign,is a milestone to control the COVID-19 pandemic.Gold nanoparticles(AuNPs)can indeed play a crucial role in this context,as their physicochemical,optics and electronics properties are being extensively used in photothermal therapy(PTT),radiation therapy(RT),drug delivery and diagnostic.AuNPs can be synthesized by several approaches to obtain different sizes and shapes that can be easily functionalized with many kinds of molecules such as antibodies,proteins,probes,and lipids.In addition,AuNPs showed high biocompatibility making them useful tool in medicine field.We thus reviewed here the most relevant evidence on AuNPs as effective way to detect the presence of SARS-CoV-2 antigens.We trust future diagnostic efforts must take this‘old-fashioned’nanotechnology tool into consideration for the development and commercialization of reliable and feasible detection kits.