Controlled coupling and characterization of oyster (Crassostrea gigas) ferritin with gold nanostars

Ferritin has good thermal stability,resistance to certain acids and bases,and targeting,and has broad application prospects in the synthesis of gold nanostars(AuNS).In this study,we screened monodisperse AuNS with uniform particle size and morphology through a one-step synthesis method and coupled the synthesized AuNS with oyster ferritin(GF1).The results showed that the surface plasmon resonance(SPR)peaks of the coupled GF1@AuNS changed signifi cantly,and the changes in infrared spectra and potential confirmed the success of the synthesis,while the microscopic morphology showed an increase in particle size and surface peak coverage.Furthermore,GF1@AuNS does not induce cell death in the 100µmol/L range,is highly stable in physiological environments,and exhibits good X-ray attenuation in micro-computed tomography.Due to the unique functional activity of ferritin and AuNS,GF1@AuNS has potential applications in food detection and drug development in the future.

Human natural killer cells for targeting delivery of gold nanostars and bimodal imaging directed photothermal/photodynamic therapy and immunotherapy

Objective:To construct a novel nanoplatform GNS@CaCO3/Ce6-NK by loading the CaCO3-coated gold nanostars(GNSs)with Chlorin e6 molecules(Ce6)into human peripheral blood mononuclear cells(PBMCs)-derived NK cells for tumor targeted therapy.Methods:GNS@CaCO3/Ce6 nanoparticles were prepared and characterized by TEM and UV-vis.The cell surface markers and cytokines secretion of NK cells before and after loading the GNS@CaCO3/Ce6 nanoparticles were detected by Flow Cytometry(FCM)and ELISA.Effects of the GNS@CaCO3/Ce6-NK cells on A549 cancer cells was determined by FCM and CCK-8.Intracellular fluorescent signals of GNS@CaCO3/Ce6-NK cells were detected via Confocal laser scanning microscopic(CLSM)and FCM at different time points.Intracellular ROS generation of GNS@CaCO3/Ce6-NK cells under laser irradiation were examined by FCM.The distribution of GNS@CaCO3/Ce6-NK in A549 tumor-bearing mice were observed by fluorescence imaging and PA imaging.The combination therapy of GNS@CaCO3/Ce6-NK under laser irradiation were investigated on tumor-bearing mice.Results:The coated CaC03 shell on the surface of GNSs exhibited prominent delivery and protection effect of Ce6 during the cellular uptake process.The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells possessed bimodal functions of fluorescence imaging and photoacoustic imaging.The as-prepared multifunctional GNS@CaCO3/Ce6-NK cells could actively target tumor tissues with the enhanced photothermal/photodynamic therapy and immunotherapy.Conclusions:The GNS@CaCO3/Ce6-NK shows effective tumor-targeting ability and prominent therapeutic efficacy toward lung cancer A549 tumor-bearing mice.Through fully utilizing the features of GNSs and NK cells,this new nanoplatform provides a new synergistic strategy for enhanced photothermal/photodynamic therapy and immunotherapy in the field of anticancer development in the near future.

Laser Pulse Duration Optimization for Photothermal Therapy with Gold Nanostars

Photothermal therapy (PTT), which utilizes light radiation to create localized heating effect in the targeted areas, is a promising solution for highly specific yet minimally invasive cancer therapy. PTT uses photothermal agents, which are usually nanoparticles that absorb strongly in the near-infrared optical window where minimal tissue absorption occurs. Photothermal agents are also highly functionalized to target at specific tumor sites. Gold nanostar is an ideal candidate for photothermal agents, because it not only has a Surface Plasmon Resonance in the near-infrared, but also can be easily produced and purified, and is extremely versatile in the drug delivery process. In order to achieve maximum amount of localized heating, pulse lasers are usually used in laser ablation processes like photothermal therapy. However, intensive laser radiation can cause damage to regular tissues as well the nanostructures themselves. Therefore, identifying the optimal pulse duration to effectively generate localized heating in the tumorous tissues while keeping the normal tissues and the nanostructures intact is important to achieving optimal photo-therapeutic results. This manuscript provides a numerical calculation method with Comsol Multiphysics to optimize the pulse condition of the gold nanostars under photothermal therapy settings. Based on results, gold nanostar displays significant temperature heterogeneity under femtosecond and picosecond laser radiation, while nanosecond laser only induces rather uniform heating effects across the entire gold nanostar particle. This finding indicates that femtosecond laser, which is the most common type of laser used for ablation, is likely to melt the tip of the gold nanostar before the nanostar body reaches a reasonably high temperature. Picosecond and nanosecond lasers are much less likely to induce such dramatic morphology change. This study offers important insight into finding the optimal condition for photothermal therapy with maximal efficacy and minimal damage.

Selective deposition of a MOF at the spikes of Au nanostars for SERS detection

In the pursuit of advancing molecular sensing through surface-enhanced Raman spectroscopy(SERS),the combination of plasmonic nanoparticles and metal-organic frameworks(MOFs)has emerged as a highly effective approach to enhance the sensitivity and selectivity of SERS substrates.However,most prior investigations have predominantly focused on MOF-coated plasmonic nanoparticles in core@shell or layer-by-layer configurations,leaving a notable knowledge gap in exploring alternative configurations.Herein we present a facile method to construct a particle-on-mirror architecture by selectively coating a MOF,zeolitic imidazolate framework-8(ZIF-8),onto the tips of Au nanostars and subsequently depositing the resultant nanoparticles onto a Au film.This design integrates the electric field enhancement at the sharp tips and nanogaps,along with the molecular enrichment function within the porous MOF immobilized at the tips and nanogaps,leading to a substantial boost in the SERS signal intensity.Such a unique SERS platform enables consistent and outstanding SERS performance for analytes of different sizes.This work opens up a promising strategy for constructing multifunctional nanostructures for sensitive SERS detection in real-life scenarios.

Real-time in situ observation of P53-mediated cascade activation of apoptotic pathways with nucleic acid multicolor fluorescent probes based on symmetrical gold nanostars

T-2 toxin,one of the most dangerous natural pollutants,induces apoptosis through multiple pathways.Amongst,P53 mediated apoptosis pathway,an important collection of molecules,plays a key role in cell vital activity.Real-time monitoring of upstream and downstream activation relationships of P53 mRNA,Bax mRNA,and cytochrome c(Cyt c)in signaling pathways is of great significance for understanding the apoptotic machinery in human physiology.In this work,a novel nucleic acid multicolor fluorescent probe,based on silica-coated symmetric gold nanostars(S-AuNSs@SiO_(2)),was developed for highly sensitive in situ real-time imaging of P53 mRNA,Bax mRNA,and Cyt c during T-2 toxin-induced apoptosis.The nucleic acid chains modified with carboxyl groups were modified on the surface of S-AuNSs@SiO_(2)by amide reaction.The complementary chains of targeted mRNA and the aptamer of targeted Cyt c were modified with different fluorophores,respectively,and successfully hybridized on S-AuNSs@SiO_(2)surface.When targets were present,the fluorescent chains bound to the targets and detached from the material,resulting in the quenched fluorescence being revived.The probes based on S-AuNSs showed excellent performance is partly ascribed to the presence of 20 symmetric“hot spots”.Notably,the amide-bonded probe exhibited excellent anti-interference capability against biological agents(nucleases and biothiols).During the real-time fluorescence imaging of T-2 toxin-induced apoptosis,the corresponding fluorescence signals of P53 mRNA,Bax mRNA,and Cyt c were observed sequentially.Therefore,S-AuNSs@SiO_(2)probe not only provides a novel tool for real-time monitoring of apoptosis pathways cascade but also has considerable potential in disease diagnosis and pharmaceutical medical.

The Fabrication and Detection Performance of High Sensitivity Au-Ag Alloy Nanostar/Paper Flexible Surface Enhanced Raman Spectroscopy Sensors

Au-Ag alloy nanostars based flexible paper surface enhanced Raman spectroscopy sensors were fabricated through simple nanostar coating on regular office paper,and the surface enhanced Raman spectroscopy detection performances were investigated using crystal violet dye analyte.Au-Ag nanostars with sharp tips were synthesized via metal ions reduction method.Transmission electron microscope images,X-Ray diffraction pattern and energy dispersive spectroscopy elemental mapping confirmed the nanostar geometry and Au/Ag components of the nanostructure.UV-Vis-NIR absorption spectrum shows wide local surface plasmon resonance induced optical extinction.In addition,finite-difference time-domain simulation shows much stronger electromagnetic field from nanostars than from sphere nanoparticle.The effect of coating layer on Raman signal intensities was discussed,and optimized 5-layer coating with best Raman signal was obtained.The Au-Ag nanostatrs homogeneously distribute on paper fiber surface.The detection limit is 10-10 M,and the relationship between analyte concentrations and Raman signal intensities shows well linear,for potential quantitative analysis.The calculated enhancement factor is 4.795×10^(6).The flexible paper surface enhanced Raman spectroscopy sensors could be applied for trace chemical and biology molecule detection.

Exposing Cu-rich {110} active facets in PtCu nanostars for boosting electrochemical performance toward multiple liquid fuels electrooxidation

In catalysis,tuning the structural composition of the metal alloy is known as an efficient way to optimize the catalytic activity.This work presents the synthesis of compositional segregated six-armed PtCu nanostars via a facile solvothermal method and their distinct composition-structure-dependent performances in electrooxidation processes.The alloy is shown to have a unique six arms with a Cu-rich dodecahedral core,mainly composed of {110} facets and exhibit superior catalytic activity toward alcohols electrooxidation compared to the hollow counterpart where Cu was selectively etched.Density functional theory (DFT) calculations suggest that the formation of hydroxyl intermediate (OH^*) is crucial to detoxify CO poisoning during the electrooxidation processes.The addition of Cu is found to effectively adjust the d band location of the alloy catalyst and thus enhance the formation of ^*OH intermediate from water splitting,which decreases the coverage of ^*CO intermediate.Our work demonstrates that the unique compositional anisotropy in alloy catalyst may boost their applications in electrocatalysis and provides a methodology for the design of this type catalyst.

In situ synthesis of gold nanostars within liposomes for controlled drug release and photoacoustic imaging

This report describes the design and synthesis of gold nanostars(AuNSs) containing liposomes by the in situ reduction of gold precursor,HAuCU(pre-encapsulated within the liposomes) through HEPES diffusion and reduction.Compared with the conventional process that encapsulates the pre-synthesized gold nanoparticles into liposomes during the thin-film hydration step,this facile and convenient method allows the formation and simultaneous encapsulation of AuNSs within liposomes.The absorption spectra of AuNSs can be tuned between visible and near infra-red(NIR) regions by controlling the size and morphology of AuNSs through varying the concentrations of HAuCU and HEPES.As a proof of concept,we demonstrate the synthesis of AuNSs with a maximum absorbance at 803 nm within the temperature-sensitive liposomes.These liposomes can produce stronger photoacoustic signals(1.5 fold) in the NIR region than blood.Furthermore,when there are drugs(i.e.,doxorubicin) within these liposomes,the irradiation with the NIR pulse laser will disrupt the liposomes and trigger the 100%release of these pre-encapsulated drugs within 10 seconds.In comparison,there is neglectable contrast enhancement or minor release(10%) of drugs for the pure liposomes under the same conditions.Finally,cell experiment shows the potential therapeutic application of this system.

Integrin α_(v)β_(3)-targeted polydopamine-coated gold nanostars for photothermal ablation therapy of hepatocellular carcinoma

Photothermal therapy(PTT)has emerged as a promising cancer therapeutic method.In this study,Arg-Gly-Asp(RGD)peptide-conjugated polydopamine-coated gold nanostars(Au@PDA-RGD NPs)were prepared for targeting PTT of hepatocellular carcinoma(HCC).A polydopamine(PDA)shell was coated on the surface of gold nanostars by the oxidative self-polymerization of dopamine(termed as Au@PDA NPs).Au@PDA NPs were further functionalized with polyethylene glycol and RGD peptide to improve biocompatibility as well as selectivity toward the HCC cells.Au@PDARGD NPs showed an intense absorption at 822 nm,which makes them suitable for near-infraredexcited PTT.Our results indicated that the Au@PDA-RGD NPs were effective for the PTT therapy of the α_(v)β_(3) integrin receptor-overexpressed HepG2 cells in vitro.Further antitumor mechanism studies showed that the Au@PDA-RGD NPs-based PTT induced human liver cancer cells death via the mitochondrial-lysosomal and autophagy pathways.In vivo experiments showed that Au@PDARGD NPs had excellent tumor treatment efficiency and negligible side effects.Thus,our study showed that Au@PDA-RGD NPs could offer an excellent nanoplatform for PTT of HCC.

Synthesis of different-sized gold nanostars for Raman bioimaging and photothermal therapy in cancer nanotheranostics

Gold nanoparticles(AuNPs) have been attractive for nanomedicine because of their pronounced optical properties.Here,we customerized the methods to synthesize two types of gold nanostars,Au nanostars-1 and Au nanostars-2,which have different spire lengths and optical properties,and also spherical AuNPs.Compared to nanospheres,gold nanostars were less toxic to a variety of cells,including macrophages.Au nanostars-1 and Au nanostars-2 also manifested a similar pattern of tissue distribution upon in vivo administration in mice to that of nanospheres,and but reveled less liver retention than nanospheres.Due to their strong absorption in the near-infrared(NIR),Au nanostars-2 induced a strong hyperthermia effect in vitro upon excitation at 808 nm,and elicited a robust photothermal therapy(PTT) efficacy in ablating tumors in a mouse model of orthotopic breast cancer using 4T1 breast cancer cells.Meanwhile,Au nanostars-1 showed a great capability to enhance the Raman signal through surface-enhanced Raman spectroscopy(SERS) in 4T1 cells.Our combined results opened a new avenue to develop Au nanostars for cancer imaging and therapy.

Controllable Preparation of Plasmonic Gold Nanostars for Enhanced Photothermal and SERS Effects

Gold nanostars(Au NSs)are asymmetric anisotropic nanomaterials with sharp edge structure.As a promising branched nanomaterial,Au NS has excellent plasmonic absorption and scattering properties.In order to tune the plasmonic photothermal and surface-enhanced Raman scattering(SERS)activity of Au NSs to obtain the desired characteristics,the ffects of reagents on the local surface plasmon resonance(LSPR)bands of Au NSs were studied and the morphology and size were regulated.Nanoparticles with different sharp edges were synthesized to make their local plasmon resonance mode tunable in the visible and near-infrared region.The effects of the number and sharpness of different tips under the control of AgNO3 on the photothermal response of Au NSs and the SERS ac-tivity and their mechanism were discussed in detail.The results show that as the length of the branch tip becomes longer and the sharpness increases,the plasmonic photothermal effect of Au NSs is strengthened,and the photother-mal conversion efficiency is the highest up to 40%when the length of Au NSs is the longest.Au NSs with high SERS activity are used for the Raman detection substrate.Based on this property,the quantitative detection of the pesticide thiram is achieved.

Topological Aspects of Dendrimers via Connection-Based Descriptors

Topological indices(TIs)have been practiced for distinct wide-ranging physicochemical applications,especially used to characterize and model the chemical structures of various molecular compounds such as dendrimers,nanotubes and neural networks with respect to their certain properties such as solubility,chemical stability and low cytotoxicity.Dendrimers are prolonged artificially synthesized or amalgamated natural macromolecules with a sequential layer of branches enclosing a central core.A present-day trend in mathematical and computational chemistry is the characterization of molecular structure by applying topological approaches,including numerical graph invariants.Among topological descriptors,Zagreb connection indices(ZCIs)have much importance.This manuscript involves the establishment of general results to calculate ZCIs,namely first ZCI(FZCI),second ZCI(SZCI),third ZCI(TZCI),modified FZCI,modified SZCI and modified TZCI of two special types of dendrimers nanostars,namely,poly propylene imine octamin(PPIO)dendrimer and poly(propyl)ether imine(PPEtIm)dendrimer.Furthermore,we provide the numerical and graphical comparative analysis of our calculated results for both types of dendrimers with each other.

Anisotropic gold nanoparticles: Preparation and applications in catalysis

Despite the high amount of scientific work dedicated to the gold nanoparticles in catalysis, most of the research has been performed utilising supported nanoparticles obtained by traditional impreg‐nation of gold salts onto a support, co‐precipitation or deposition‐precipitation methods which do not benefit from the recent advances in nanotechnologies. Only more recently, gold catalyst scien‐tists have been exploiting the potential of preforming the metal nanoparticles in a colloidal suspen‐sion before immobilisation with great results in terms of catalytic activity and the morphology con‐trol of mono‐and bimetallic catalysts. On the other hand, the last decade has seen the emergence of more advanced control in gold metal nanoparticle synthesis, resulting in a variety of anisotropic gold nanoparticles with easily accessible new morphologies that offer control over the coordination of surface atoms and the optical properties of the nanoparticles （tunable plasmon band） with im‐mense relevance for catalysis. Such morphologies include nanorods, nanostars, nanoflowers, den‐dritic nanostructures or polyhedral nanoparticles to mention a few. In addition to highlighting newly developed methods and properties of anisotropic gold nanoparticles, in this review we ex‐amine the emerging literature that clearly indicates the often superior catalytic performance and amazing potential of these nanoparticles to transform the field of heterogeneous catalysis by gold by offering potentially higher catalytic performance, control over exposed active sites, robustness and tunability for thermal‐, electro‐and photocatalysis.

Hot spots enriched plasmonic nanostructure-induced random lasing of quantum dots thin film

Here,a plasmon-enhanced random laser was achieved by incorporating gold nanostars（NS） into disordered polymer and Cd Se/Zn S quantum dots（QDs） gain medium films,in which the surface plasmon resonance of gold NS can greatly enhance the scattering cross section and bring a large gain volume.The random distribution of gold NS in the gain medium film formed a laser-mode resonator.Under a single-pulse pumping,the scattering center of gold NS-based random laser exhibits enhanced performance of a lasing threshold of 0.8 m J/cm^2 and a full width as narrow as 6 nm at half maximum.By utilizing the local enhancement characteristic of the electric field at the sharp apexes of the gold NS,the emission intensity of the random laser was increased.In addition,the gold NS showed higher thermal stability than the silver nanoparticles,withstanding high temperature heating up to 200？C.The results of metal nanostructures with enriched hot spots and excellent temperature stability have tremendous potential applications in the fields of biological identification,medical diagnostics,lighting,and display devices.

Hierarchical Nanogold Labels to Improve the Sensitivity of Lateral Flow Immunoassay

Lateral flow immunoassay(LFIA) is a widely used express method and offers advantages such as a short analysis time, simplicity of testing and result evaluation.However, an LFIA based on gold nanospheres lacks the desired sensitivity, thereby limiting its wide applications.In this study, spherical nanogold labels along with new types of nanogold labels such as gold nanopopcorns and nanostars were prepared, characterized, and applied for LFIA of model protein antigen procalcitonin. It was found that the label with a structure close to spherical provided more uniform distribution of specific antibodies on its surface, indicative of its suitability for this type of analysis.LFIA using gold nanopopcorns as a label allowed procalcitonin detection over a linear range of 0.5–10 ng mL^(-1) with the limit of detection of 0.1 ng mL^(-1), which was fivefold higher than the sensitivity of the assay with gold nanospheres. Another approach to improve the sensitivity of the assay included the silver enhancement method,which was used to compare the amplification of LFIA for procalcitonin detection. The sensitivity of procalcitonin determination by this method was 10 times better the sensitivity of the conventional LFIA with gold nanosphere as a label. The proposed approach of LFIA based on gold nanopopcorns improved the detection sensitivity without additional steps and prevented the increased consumption of specific reagents(antibodies).

The Multiplicative Zagreb Indices of Nanostructures and Chains

In theoretical chemistry, the researchers use graph models to express the structure of molecular, and the Zagreb indices and multiplicative Zagreb indices defined on molecular graph G are applied to measure the chemical characteristics of compounds and drugs. In this paper, we present the exact expressions of multiplicative Zagreb indices for certain important chemical structures like nanotube, nanostar and polyomino chain.

A review of metal nanoparticle-based surface-enhanced Raman scattering substrates for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)detection Special Collection:Distinguished Australian Researchers

Monitoring an infectious disease early using highly sensitive and non-invasive techniques is critical for human health.Interestingly,the development of surfaceenhanced Raman scattering(SERS)for biological detection ideally fits these medical requirements and is rapidly growing as a powerful diagnostic tool.SERS can enhance the Raman signal of the target molecule by more than 106 after the adsorption of the molecule on the plasmonic nanostructured surface.This review provides an overview of the use of gold and silver nanoparticles in SERS substrate designs,followed by the development of these SERS substrates in severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)detection.

How toxic are gold nanoparticles？ The state-of-the-art

With the growing interest in the applications of gold nanoparticles in biotechnology and their physiological effects, possible toxicity of gold nanoparticles is becoming an increasingly important issue. A large number of studies carried out over the past few years under a variety of experimental conditions and following different protocols have produced conflicting results, leading to divergent views about the actual safety of gold nanoparticles in human applications. This work is intended to provide an overview of the most recent experimental results and thereby summarize current state-of-the-art. Rather than presenting a comprehensive review of the available literature in this field, which would be impractically broad, we have selected representative examples of both in vivo and in vitro studies, which clearly demonstrate the need for urgent and rigorous standardization of experimental protocols. Despite their significant potential, the safety of gold nanoparticles is highly controversial at this time, and important concerns have been raised that need to be properly addressed. Factors such as shape, size, surface charge, coating, and surface functionalization are expected to influence the interactions of particles with biological systems to a different extent, resulting in different outcomes and influencing the potential of gold nanoparticles for biomedical applications. Moreover, despite continuous attempts to establish a correlation between structure of the particles and their interactions with biological systems, we are still far from elucidating the toxicological profile of gold nanoparticles in an indisputable manner. This review is intended to contribute towards this goal, offering a number of suggestions on how to achieve the systematization of data on the most relevant physico-chemical parameters, which govern and control the toxicity of ~old nanot^articles at cellular and whole-organism levels.

Surface-enhanced Raman scattering nanosensors for in vivo detection of nucleic acid targets in a large animal model

Although nanotechnology has led to important advances in in vitro diagnostics, the development of nanosensors for in vivo detection remains very challenging. Here, we demonstrated the proof-of-principle of in vivo detection of nudeic acid targets using a promising type of surface-enhanced Raman scattering （SERS） nanosensor implanted in the skin of a large animal model （pig）. The in vivo nanosensor used in this study involves the ＂inverse molecular sentinel＂ detection scheme using plasmonics-active nanostars, which have tunable absorption bands in the near infrared region of the ＂tissue optical window＂, rendering them efficient as an optical sensing platform for in vivo optical detection. Ex vivo measurements were also performed using human skin grafts to demonstrate the detection of SERS nanosensors through tissue. In this stud, a new core--shell nanorattle probe with Raman reporters trapped between the core and shell was utilized as an internal standard system for self-calibration. These results illustrate the usefulness and translational potential of the SERS nanosensor for in vivo biosensing.