超顺磁金纳米壳复合颗粒的粒径调控及其诊疗应用

利用原位还原-种子生长法制备了超顺磁金纳米壳复合颗粒(SGNs), 研究了其粒径调控的方法并对其体外/体内磁共振成像(MRI)和光热治疗(PT)性能进行了测试。结果表明, 通过改变Fe₃O₄的加入量可方便地调控SGNs的粒径, 并成功制备了粒径分别为100、150和200 nm的SGNs复合颗粒。这些不同粒径的纳米复合颗粒均具有规则的球形形貌、较窄的粒径分布和单分散性。经巯基-聚乙二醇(SH-PEG)修饰后, 不同粒径的复合颗粒(SGNs-PEG)均表现出较强的MRI成像和光热转换能力。其中, 粒径为150 nm的复合颗粒对808 nm激光具有最强的吸收能力和光热转换效率, 体外和体内可升高温度分别达37 ℃和25 ℃, 同时具有较优异的MRI成像造影能力。因此, 在MDA-MB-435荷瘤小鼠肿瘤部位注射该复合颗粒后, 可先对肿瘤部位进行很好的成像诊断, 再利用激光照射通过光热转换有效地杀灭肿瘤细胞, 这为实现肿瘤诊疗的一体化提供了可能。     

金纳米粒子的最新研究进展

金纳米粒子是最稳定的金属纳米粒子之一，由于其具有优良的稳定性和光学性质，使其在许多领域有着广阔的应用前景。本文主要对金纳米粒子和表面修饰金纳米粒子的制备方法进行分析总结，指出各种方法的制备原理及特点。同时，阐述了金纳米粒子的一些特殊性能，如：表面吸收带效应、荧光效应、量子尺寸效应、单电子跃迁等。并对金纳米粒子的应用进行了展望。     

纳米金在比色传感分析中的应用

纳米金具有良好的生物相容性,易于进行表面修饰,且具有独特的光学性能。在紫外可见光谱中,纳米金所产生的吸收峰的位置与纳米金粒子之间的距离、颗粒(或聚集态)大小和形状有关,吸收峰的强度与溶液中纳米金的浓度线性相关。因此,纳米金在开发比色传感器方面具有独特的优势。评述了近年来生物大分子-纳米金复合物、有机小分子-纳米金复合物、未修饰的纳米金、纳米金生长在比色传感分析中的应用以及固体纳米金比色传感器的研究进展,结合实例阐述了纳米金比色传感分析的机理,并对其优缺点进行了总结,对未来的发展方向进行了展望。     

金纳米结构光热转换材料的研究进展

金纳米结构材料具有重要的光热转换性质,在癌症治疗方面引起了全世界的高度关注.综述了金纳米结构光热转换材料包括纳米球、纳米棒、纳米壳、纳米笼以及纳米簇等的制备方法和进展,随后总结了其表面功能化的3种方法,即利用双功能的配体直接进行配体交换、二氧化硅包覆、聚合物包覆.最后介绍了其在激光诱导的药物释放、光热治疗、近红外热成像等生物医药方面的应用.     

微乳法制备纳米金及其生物电催化性能研究

纳米金具有特殊的电催化性能。采用水/AOT(2-乙基己基琥珀酸酯磺酸钠)/环己烷微乳体系制备纳米金颗粒,通过改变水与AOT的物质的量比(ω)制备不同尺寸的纳米金,并通过透射电镜、紫外分光光度计、电化学工作站对纳米金颗粒的形貌尺寸、紫外吸收光谱、电化学性能进行分析与研究。结果表明,纳米金呈球形,尺寸均一,单分散性较好。通过对纳米金颗粒电催化析氢性能的测试发现,纳米金粒子分散性较好,形成的是均相溶液,纳米金粒子与Pt/C相比电催化性能稍弱,但是与纳米银、金铁合金和纳米硒化钨相比都显现出较好的电催化活性,说明纳米金粒子具有比较优良的电催化性能,为纳米金颗粒在生物电催化领域的应用奠定理论基础。     

小型金纳米棒的制备

用种子生长法合成小型金纳米棒,改变合成参数可调控其形貌和性能。使用紫外-可见-近红外分光光度计和透射电子显微镜(TEM)测试和观察了金纳米棒的消光特性和形貌,研究了AgNO₃、十六烷基三甲基溴化铵(CTAB)和籽晶的用量对金纳米棒的形貌和性能的影响。结果表明：在不同条件下制备的金纳米棒具有良好的重现性。在(0.01 mol/L) AgNO3用量为0.035 mL、(0.1 mol/L) CTAB用量为11 mL、籽晶用量为1.1 mL的最佳条件下合成的金纳米棒,其长径比约为3.8,平均长度约为34 nm,形貌均匀性和分散性良好。这种小型金纳米棒可用于检测残留物福美双(Thiram)。     

氧化硅/金纳米壳层的制备及其在纳米医学中应用的研究现状

氧化硅/金纳米壳层因具有由其核/壳相对尺寸所决定的特殊光学性能和良好的生物相容性, 所以在纳米医学等许多领域得到了广泛的重视. 本文综述了氧化硅/金纳米壳层的研究现状, 总结了相关的制备方法, 评述了在纳米医学中的重要应用, 并对其研究前景进行了展望.     

纳米TiO2和纳米ZnO的紫外光学特性及其在聚丙烯抗老化改性中的应用研究

采用水悬浮液法研究比较了金红石型纳米TiO2和纳米ZnO的紫外-可见光学特性,结果表明金红石型纳米TiO2具有比纳米ZnO更加优异的紫外线屏蔽性能,并对两种材料的屏蔽机理进行了分析;通过熔融共混法制备了金红石型纳米TiO2和纳米ZnO两类改性PP材料,用氙灯耐气候试验机对所制备材料进行了28天人工气候加速老化,对比测试了纯PP和两种改性PP老化前后的力学性能和外观变化规律,结果表明添加少量金红石型纳米TiO2或纳米ZnO都可以大幅度的提高PP的抗老化性能,而金红石型纳米TiO2改性PP的抗老化性能要明显优于纳米ZnO改性PP材料.文章最后用SEM对纳米TiO2在PP材料中的分散情况进行了分析.     

金纳米粒子的绿色可控合成及其合成机理研究

以水溶性淀粉为还原剂,以氯金酸为前驱体,快速合成了单分散的金纳米粒子。采用紫外-可见吸收光谱(UV-Vis)、透射电子显微镜(TEM)、X射线衍射(XRD)、能谱仪(EDX)等对金纳米粒子进行表征。结果表明,合成了面心立方结构的球状金纳米粒子,其平均直径不大于40nm,表面等离子体共振吸收峰在534~552nm之间线性可调。系统考察了水溶性淀粉的水解时间、氯金酸添加量、反应时间等制备条件对金纳米粒子光学性能的影响并对金纳米粒子的合成机理进行了研究。实验发现,最佳水解时间为5min,增加反应时间或氯金酸的添加量,金纳米粒子的吸收峰均发生规律性红移。     

Janus纳米杂化材料制备研究进展

Janus纳米杂化材料是材料科学重要的研究方向之一。如何实现Janus纳米杂化材料批量制备及精确表征是目前研究的重点和难点。利用RefViz软件对Janus纳米材料的研究现状进行分析可知:Janus纳米材料研究中,有关表界面、纳米金及Janus纳米材料性能的研究是目前公认的研究热点。重点介绍了Janus纳米金杂化材料,并对其今后的发展也进行了探讨。     

Nonbleaching fluorescence of gold nanoparticles and its applications in cancer cell imaging

In this paper, we investigated the fluorescent properties of gold nanoparticles (GNPs) with several tens of nanometers by ensemble fluorescence spectrometry, fluorescence correlation spectroscopy (FCS), and fluorescence microscopy. We observed that GNPs synthesized by the citrate reduction of chloroauric acid possessed certain fluorescence, narrow full width at half-maximum (17 nm), and with an increase of particle sizes, the emission intensity showed a gradual increase while the emission wavelength remained almost constant (at 610 nm). Especially, the fluorescence of GNPs possessed the excellent behavior of antiphotobleaching under strong light illumination. Despite their low quantum yields, GNPs exhibited strong native fluorescence under relatively high excitation power. The fluorescence of GNPs could be characterized by fluorescence imaging and FCS at the single particle level. On the basis of this excellent antiphotobleaching of GNPs and easy photobleaching of cellular autofluorescence, we developed a new method for imaging of cells using GNPs as fluorescent probes. The principle of this method is that after cells stained with GNPs or GNPs bioconjugates are illuminated by strong light, the cellular autofluorescence are photobleached and the fluorescence of GNPs on cell membrane or inside cells can be collected for cell imaging. On the basis of this principle, we imaged living HeLa cells using GNPs as fluorescent probes and obtained good cell images by photobleaching of cellular autofluorescence. Furthermore, anti-EGFR/GNPs were successfully used as targeted probes for fluorescence imaging of cancer cells. Our preliminary results demonstrated that GNPs possessed excellent behaviors of antiphotobleaching and were good fluorescent probes in cell imaging. Our cellular imaging method described has potential applications in cancer diagnostics, studies, and immunoassays.     

A review of the biological synthesis of gold nanoparticles using fruit extracts: scientific potential and application

Gold nanoparticles (GNPs) are well-known nanomaterials that can be used for multiple biomedical applications. There are various methods for synthesis of GNPs using microorganisms and plants, particularly through the use of fruit extracts. Their use is due to the fact that fruit extracts are the natural concentrate of substances that possesses therapeutic properties. In this review, we aim to compare the recent studies concerning the methods for synthesis of GNPs from fruit extracts, the methods used to characterize the properties of GNPs and capping biomaterial and the potential applications of GNPs. The most frequently used methods to characterize GNPs and capping biomaterial are UV–visible spectroscopy, transmission or scanning electron microscopy, dynamic light scattering and Fourier transformation infrared spectroscopy techniques. Because of GNPs’ optoelectronic properties, biocompatibility, stability and oxidation resistance, they can be used in areas such as electronics, chemical and biological sensing, tumour imaging, drug delivery and phototherapy.     

Structural‐Engineering Rationales of Gold Nanoparticles for Cancer Theranostics

Personalized theranostics of cancer is increasingly desired, and can be realized by virtue of multifunctional nanomaterials with possible high performances. Gold nanoparticles (GNPs) are a type of especially promising candidate for cancer theranostics, because their synthesis and modification are facile, their structures and physicochemical properties are flexibly controlled, and they are also biocompatible. Especially, the localized surface plasmon resonance and multivalent coordination effects on the surface endow them with NIR light‐triggered photothermal imaging and therapy, controlled drug release, and targeted drug delivery. Although the structure, properties, and theranostic application of GNPs are considerably plentiful, no expert review systematically explains the relationships among their structure, property. and application and induces the engineering rationales of GNPs for cancer theranostics. Hence, there are no clear rules to guide the facile construction of optimal GNP structures aiming at a specific theranostic application. A series of structural‐engineering rationales of GNPs for cancer theranostics is proposed through digging out the deep relationships between the structure and properties of GNPs. These rationales will be inspiring for guiding the engineering of specific and advanced GNPs for personalized cancer theranostics.     

Using Functional Nanomaterials to Target and Regulate the Tumor Microenvironment: Diagnostic and Therapeutic Applications

Malignant tumors remain a major health burden throughout the world and effective therapeutic strategies are urgently needed. Cancer nanotechnology, as an integrated platform, has the potential to dramatically improve cancer diagnosis, imaging, and therapy, while reducing the toxicity associated with the current approaches. Tumor microenvironment is an ensemble performance of various stromal cells and extracellular matrix. The recent progress in understanding the critical roles and the underlying mechanisms of the tumor microenvironment on tumor progression has resulted in emerging diagnostic and therapeutic nanomaterials designed and engineered specifically targeting the microenvironment components. Meanwhile, the bio‐physicochemical differences between tumor and normal tissues have recently been exploited to achieve specific tumor‐targeting for cancer diagnosis and treatment. Here, the major players in the tumor microenvironment and their biochemical properties, which can be utilized for the design of multifunctional nanomaterials with the potential to target and regulate this niche, are summarized. The recent progress in engineering intelligent and versatile nanomaterials for targeting and regulating the tumor microenvironment is emphasized. Although further investigations are required to develop robust methods for more specific tumor‐targeting and well‐controlled nanomaterials, the applications of tumor microenvironment regulation‐based nanotechnology for safer and more effective anticancer nanomedicines have been proven successful and will eventually revolutionize the current landscape of cancer therapy.     

Graphite nanoplatelets and Caenorhabditis elegans: insights from an in vivo model

We evaluated the toxicity of graphite nanoplatelets (GNPs) in the model organism Caenorhabditis elegans. The GNPs resulted nontoxic by measuring longevity as well as reproductive capability end points. An imaging technique based on Fourier transform infrared spectroscopy (FT-IR) mapping was also developed to analyze the GNPs spatial distribution inside the nematodes. Conflicting reports on the in vitro antimicrobial properties of graphene-based nanomaterials prompted us to challenge the host-pathogen system C. elegans-Pseudomonas aeruginosa to assess these findings through an in vivo model.     

Synergistic effects of TiC and graphene on the microstructure and tribological properties of Al2024 matrix composites

Al matrix composites have attracted significant attention of researchers in recent years due to their lightweight, excellent mechanical and tribological properties. In this study, an Al2024 matrix hybrid composite (AMHC) reinforced with both TiC nanoparticles and graphene nanoplatelets (GNPs) was produced via a route of powder metallurgy. And its microstructure, microhardness and tribological properties are compared with those of unreinforced Al2024 alloy matrix and Al2024 matrix composites reinforced with either only TiC or GNPs. It was found that the distribution of Al₂Cu, TiC nanoparticles and GNPs in the matrix and the wear resistance are significantly improved when introducing both TiC nanoparticles and the GNPs. The wear mechanisms change from the adhesion-dominant wear for Al2024 and the other singly reinforced composites into abrasive-dominant wear for the hybrid composite. The significantly improved wear resistance of the AMHC is attributed to the synergistic effects of reinforcing and self-lubricating of the TiC and GNPs.     

Review on polymer/graphite nanoplatelet nanocomposites

Graphite nanoplatelets (GNPs) are a type of graphitic nanofillers composed of stacked 2D graphene sheets, having outstanding electrical, thermal, and mechanical properties. Furthermore, owing to the abundance of naturally existing graphite as the source material for GNPs, it is considered an ideal reinforcing component to modify the properties of polymers. The 2D confinement of GNPs to the polymer matrix and the high surface area make the GNP a distinctive nanofiller, showing superiorities in modification of most properties, compared with other carbon nanofillers. This review will summarize the development of polymer/GNP nanocomposites in recent years, including the fabrication of GNPs and its nanocomposites, processing issues, viscoelastic properties, mechanical properties, electrical and dielectric properties, thermal conductivity and thermal stability. The discussion of reinforcing effect will be based on dispersion, particle geometry, concentrations, as well as the 2D structures and exfoliation of GNPs. The synergy of GNPs with other types of carbon nanofillers used as hybrid reinforcing systems shows great potential and could significantly broaden the application of GNPs. The relevant research will also be included in this review.     

Biogenic Syntheses of Gold Nanoparticles Using Plant Extracts

A biogenic approach for the synthesis of gold nanoparticles (GNPs) by reducing chloroauric acid (HAuCl₄) with three different plant extracts (from Angelica, Hypericum, and Hamamelis) is described. The content of reducing compounds (polyphenols) in each plant extract was determined by photometric dosing. The formation of GNPs was tracked by ultraviolet-visible spectroscopy and their characterization was performed using transmission electron microscopy (TEM) and atomic force microscopy (AFM) imaging and FTIR spectra. GNPs, with diameters ranging from about 4 nm to 8 nm, were obtained at room temperature and pH value about 8. They present various shapes from spherical, to ovals, heart or polyhedral forms. Generally, the GNPs colloidal dispersions are rather stable in time, and the self assembly of GNPs is sparsely observed. However, at lower concentration of the plant extract the tendency to self aggregation of the GNPs increased. The plant extracts contain reducing agents, compounds with stabilizing effect on the GNPs, but also components which mediate their self assembly. The GNPs obtained by these biogenic syntheses have potential biological and medical applications, taking into account at least two characteristics, their size and aqueous stability.     

Effect of Retro‐Inverso Isomer of Bradykinin on Size‐Dependent Penetration of Blood–Brain Tumor Barrier

Retro‐inverso bradykinin (RI‐BK) has better metabolic stability and higher affinity for the BK type 2 (B2) receptor, compared with bradykinin. At low doses, RI‐BK can selectively enhance the permeability of the blood–brain tumor barrier (BBTB) without harming normal brain tissue. In this study, gold nanoparticles (GNPs) of size ranging from 5 to 90 nm are synthesized to assess the optimal size of nanocarriers that achieves maximum brain accumulation after the treatment of RI‐BK. The ability of the GNPs to cross the BBTB is tested in a rat C6 glioma tumor model. The results of inductively coupled plasma–mass spectrometry and transmission electron microscopy indicate that GNPs with size of 70 nm achieve maximum permeability to the glioma. The present study supports the conclusion that RI‐BK can enhance the permeability of BBTB and provides fundamental information for further development of nanomedicines or nanoprobes for glioma therapy.     

Noise-free dual-wavelength difference imaging of plasmonic resonant nanoparticles in living cells

Herein, we demonstrated a new optical microscopy method to selectively image small-size gold nanoparticles (GNPs) inside noisy living cells through determination of the difference image between the probe beam (illuminated at the resonance wavelength of GNPs, 532 nm) and the reference beam (illuminated at 473 nm). From computer simulation and single-particle imaging experiments, we demonstrated that GNPs with a diameter of 45 nm could be selectively imaged in the GNPs/cell lysates mixture and inside living cells by dual-wavelength difference (DWD) imaging. The diffusion dynamics of nucleic acids functionalized GNPs on cell membranes and the internalization kinetics of these GNPs by living cells were explored with this method. Our real-time tracking experiments showed that statistically 80% of GNPs were under restricted diffusion on the cell membrane. The cell cytoskeleton fence effect, as observed in the single-particle tracking experiments, may be one of the main factors for the restricted diffusion mode.