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.

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.

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.

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.

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.

Passively Q-switched erbium doped fiber laser using a gold nanostars based saturable absorber

In this paper, we propose and demonstrate an all-fiber passively Q-switched erbium doped fiber laser(EDFL) by using gold nanostars(GNSs) as a saturable absorber(SA) for the first time, to the best of our knowledge. In comparison with other gold nanomorphologies, GNSs have multiple localized surface plasmon resonances, which means that they can be used to construct wideband ultrafast pulse lasers. By inserting the GNS SA into an EDFL cavity pumped by a 980 nm laser diode, a stable passively Q-switched laser at 1564.5 nm was achieved for a threshold pump power of 40 mW. By gradually increasing the pump power from 40 to 120 mW, the pulse duration decreases from 12.8 to 5.3 μs and the repetition rate increases from 10 to 17 kHz. Our results indicate that the GNSs are a promising SA for constructing pulse lasers.

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.

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.

树状纳米星的修改的Szeged指数

Szeged指数以及修改的Szeged指数作为一类化学参数广泛应用于各种化学和制药工程中.通过化学分子结构的分析,给出了树状纳米星的两类修改的Szeged指数.

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).

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.

纳米管TUC_4C_8(S)和纳米环TC_4C_8(S)的拓扑指数

化合物、材料和药物的生物化学性质与其分子结构有密切的关联,通过化学拓扑指数的计算可了解化合物的性质.作为一类重要的化学参数,Szeged指数和修改的Szeged指数并广泛用于各类化学与制药学工程应用中.通过边划分方法,给出纳米管TUC_4C_8(S)和纳米环TC4C8(S)的若干基于距离的拓扑指数.

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.

紫杉醇温敏脂质体与siRNA金纳米星载药系统的构建与表征

用种子生长法制备金纳米星(gold nanostar,GNS),构建聚乙二醇(polyethylene glycol,PEG)、氨基葡萄糖(2-amino-2-deoxy-D-glucose,DG)和九聚精氨酸(9-D-arginine,9R)修饰的载COX-2 siRNA(siCOX-2)的GNS复合纳米粒[siCOX-2(9R/DG-GNS)];以薄膜分散法制备载紫杉醇温敏脂质体(paclitaxel temperature sensitive liposome,PTX-TSL);最后将siCOX-2(9R/DG-GNS)与PTX-TSL体通过巯基配位得到PTX-TSL与siCOX-2(9R/DG-GNS)共载药系统PTX-TSL-[siCOX-2(9R/DG-GNS)]。采用核磁共振、聚丙烯酰胺凝胶电泳、紫外分光光度法、琼脂糖凝胶电泳法验证了siCOX-2(9R/DG-GNS)成功构建,马尔文电位粒度仪测得PTX-TSL-[siCOX-2(9R/DG-GNS)]粒径电位分别为(292±14)nm、-(2.59±0.12)m V,透射电子显微镜结果显示其结构呈包裹磷脂双分子层的星型,808 nm激光照射下表现出良好的光热转换效率。差示扫描量热法测试PTX-TSL相变温度约为42.6℃,透析法测得其载药量为7.5%,包封率为95.4%,具有良好的温敏释药性能。因此,本复合物纳米载药系统可作为PTX与siCOX-2的共载药体系,用以抗肿瘤耐药治疗。

金种子生长法制备小尺寸金纳米星

本研究采用金种子生长法,通过优化氯金酸溶液用量、生长液pH值以及反应温度等条件,制备出一种全新的小尺寸金纳米星(Au-NSs)颗粒,方法具有可控、稳定、简单、Au-NSs粒径均一等优点。紫外-可见-近红外(UV-Vis-NIR)光谱和透射电子显微镜(TEM)检测表明,该方法制备出的Au-NSs的粒径在40nm左右,远小于常规方法制得的Au-NSs(~80nm)。最终制备条件确定为:生长液、金种溶液和抗坏血酸(AA)的体积比为600∶9∶7;生长液的pH≈3.05;制备Au-NSs的温度条件为先冰浴加入金种,回升至室温后加入AA还原。

金纳米星负载二氢卟吩e6对肺癌A549细胞的光动力效应

目的:制备负载光敏剂二氢卟吩e6(chlorin e6,Ce6)的金纳米星(gold nanostars,GNS),研究其对肺癌A549细胞的光动力作用效果。方法:GNS经巯基聚乙二醇(SH-PEG-NH2)修饰后与光敏剂Ce6振荡过夜,制备出具有光动力治疗效应的探针GNS-PEG@Ce6,检测其表征、形态和包封率,通过激光共聚焦显微镜比较A549细胞对探针GNS-PEG@Ce6与Ce6的吞噬作用。应用MTT法检测探针GNS-PEG@Ce6对A549细胞增殖的抑制效果,通过流式细胞仪检测探针GNS-PEG@Ce6与Ce6对A549细胞凋亡的影响。结果:探针GNS-PEG@Ce6的粒径为100 nm左右,具有良好的分散性和稳定性,Ce6的包封率为50%左右。探针GNS-PEG@Ce6以胞吞方式进入细胞,主要分布于细胞质内,且较Ce6能更有效地进入细胞。探针GNS-PEG@Ce6对A549细胞的增殖抑制作用强于Ce6(P<0.05),流式细胞仪检测证明了探针对细胞有极为明显的致凋亡效果。结论:以GNS作为载体能有效地增加肺癌A549细胞对Ce6的摄取,从而进一步增强Ce6对肺癌A549细胞的杀伤效果。

基于纳米TiO2和金纳米星的光电化学适配体传感器检测Hg2+的研究

构建了一种适配体修饰的Hg^2+传感器,以氧化铟锡(ITO)导电玻璃为基底电极,纳米TiO2为光电活性材料,通过金纳米星固定特异性识别单元巯基修饰适配体。当适配体特异性识别Hg^2+时,适配体富碱基T序列与Hg^2+结合形成折叠的发卡结构,传感器界面发生改变从而实现Hg^2+定量分析。采用时间-电流法、交流阻抗法等电化学方法对所构建的传感器检测性能进行研究。实验结果表明,在优化实验条件下,该方法用于检测Hg^2+的线性范围为1.0×10^-9~5.0×10^-7 mol/L,检测限为3.1×10^-10 mol/L。该传感器制备过程简单,具有较高的检测灵敏度,较高的稳定性和可重复性。