Biological response of hydrogels embedding gold nanoparticles

A nanocomposite hydrogel based on natural polysaccharides and gold nanoparticles (ACnAu) has been prepared and its biological effects were tested in vitro with both bacteria and eukaryotic cells. Antimicrobial tests showed that AC-nAu gels are effective in killing both gram+ (Staphylococcus aureus) and gram- (Pseudomonas aeruginosa) bacteria. LDH assays pointed at a toxic effect towards eukaryotic cell-lines (HepG2 and MG63), in contrast with the case of silver-based hydrogels; cytofluorimetry studies demonstrated an apoptosis-related mechanism induced by increase of ROS intracellular level which leads to cell death after 24 h of direct contact with AC-nAu gels. In vivo biocompatibility has been evaluated in a rat model, investigating the peri-implant soft tissue reaction after 1 month of implantation. The results show that silver-containing samples induced a fibrotic capsule of the same average thickness of the control sample (devoid of nanoparticles) (～50 μm), while in the case of gold containing materials the fibrotic capsule was thicker (～100 μm), confirming a higher biocompatibility for silver-based samples than for gold-based ones.     

Surface-functionalized silica-coated gold nanoparticles and their bioapplications

Monodisperse Au at SiO₂ nanoparticles has been functionalized with carboxylic groups for further bioconjugation with amino-terminated oligonucleotides. The oligonucleotide-modified Au at SiO₂ nanoprobes have been applied in the fast colorimetric DNA based on the sequence-specific hybridization properties of DNA. Self-assembling behavior of Au at SiO₂ nanoparticles was also investigated.     

Eco-friendly synthesis of gold nanoparticles using fruit extracts and in vitro anticancer studies

Gold nanoparticles are biocompatible and are having several applications in biomedical Sciences and Engineering. Integration of nanoscience in medicine leads to the development of biomedical products that helps the Society in a faster and safer manner. In the present research work, bioreduction and biofunctionalization of gold nanoparticles are performed with fruit extracts of Aegle marmelos, Eugenia jambolana and soursop. The nanoparticles are characterized using UV–Vis spectroscopy, Transmission Electron Microscopy, Fourier Transform Infrared Spectroscopy and Zeta potentiometer. The qualitative phytochemical analysis of the fruit extracts shows the presence of alkaloids, amino acid, flavonoids, phenol, proteins, tannin, reducing sugars and total Sugars. The in vitro anticancer activity was confirmed by MTT assay on the human breast cancer cell line MCF-7 at different concentrations. The flavonoids present in the fruit extracts are potential reducing agent which is responsible for the formation of gold nanoparticles. Stabilization of gold nanoparticles are performed by the carboxylate group present in the proteins. Also, the nanoparticles are held apart from each other by the electrostatic repulsions that exist due to the presence of like charges surrounding the gold nanoparticles. This study proves that the fruit extracts can be used for the synthesis and stabilization of gold nanoparticles. Further, the engineered nanoparticles capped with bioactive compounds are potential anticancer agents against breast cancer cell line MCF-7.     

In vitro and in vivo degradation of an injectable bone repair composite

In vitro and in vivo degradation behaviors of an injectable bone regeneration composite (IBRC) which comprised of nano-hydroxyapatite/collagen (nHAC) particles in alginate hydrogel carrier were investigated. In vitro degradation quantitative testing indicated that the alginate had a faster degradation rate in simulated body fluid (SBF) than in deionized water at 37 °C. Similarly, IBRC also had a higher degradation rate in SBF than in deionized water at 37 °C, which was evaluated by alginate molecular weight measurement, mechanical properties test and degradation kinetics evaluation. But molecular weight of alginate degraded slower in IBRC than that in aqueous solution. In vitro results showed that degradation medium SBF had influence on degradation of alginate molecules. In the in vivo degradation study, surprisingly, there was no obvious decreasing of molecular weight of alginate from 0 to 8 weeks. IBRC degraded mostly after 24 weeks implantation and was replaced by connective tissue. No fibrous capsule and acute inflammatory reaction were found during the observed 24 weeks after IBRC implantation. There is only a mild short-term inflammatory response in rat dorsum muscle. These results indicated that IBRC had a controllable degradability and biocompatibility. Therefore, IBRC may be a promising degradable material for bone repair and bone tissue engineering.     

磁性铁氧化物纳米粒子制备及其体内应用研究

磁性铁氧化物纳米粒子由于其生物相容性和低毒性而广泛的应用于生物医学领域。本文总结了近年来制备各种磁性铁氧化物纳米粒子的方法,比较了它们在粒径、结晶度以及制备条件等方面的优缺点,概括了对其进行表面修饰改性材料的种类,阐述近年来磁性铁氧化物纳米粒子在体内应用中药物运输、磁共振成像、磁热疗方面的进展,并指出当前应用中的主要方向和亟待解决的问题。     

Size sorting of citrate reduced gold nanoparticles by sedimentation field-flow fractionation

Gold nanoparticles (GNPs) have been synthesized through the citrate reduction method; the citrate/gold(III) ratio was changed from 1:1 up to 10:1 and the size of the resulting nanoparticles was measured by sedimentation field-flow fractionation (SdFFF). Experimental data showed that the GNPs size decreases in the ratio range 1:1–3:1 and then increases from 5:1 to 10:1 passing through a plateau region in between, and is almost independent of the precursor solution concentrations. In the zone of minimum diameters the synthetic process does not produce monodispersed GNPs but often multiple distributions, very close in size, are observed as evidenced by the particle size distributions (PSDs) derived from the SdFFF fractograms. UV–vis spectrophotometry, being the most common technique employed in the optical characterization of nanoparticles suspensions, was used throughout this work. A confirmation of the nucleation–aggregation–fragmentation mechanism was inferred from the cross-correlation between UV–vis and SdFFF results.     

Site-selective immobilization of gold nanoparticles functionalized with DNA oligomers

The organization of metal and semiconductor nanoparticles to form micro- and nanostructured assemblies is currently of tremendous interest. This communication reports on the utilization of DNA molecules as positioning elements for generating microstructured surface architecture from gold nanoparticles. Citrate-passivated 40 nm gold colloids were modified by chemisorptive coupling with a 5′-thiol-derivatized DNA oligomer. The nucleic acid was used as a molecular handle for the specific immobilization on solid supports, previously functionalized with capture DNA oligomers, complementary to the nanoparticle-bound DNA. As a consequence of the enormous specificity of nucleic acid hybridization, the DNA-directed immobilization (DDI) allows, to site-specifically target the hybrid nanoparticles to microlocations which contain the complementary oligomers. The site-selectivity of the surface adsorption is demonstrated by immobilizing the gold colloids on a DNA microarray on a glass cover slide. Moreover, scanning force microscopy (SFM) analysis, used to characterize the intermediate steps of the DDI on a gold substrate, provided initial insights into the specificity and efficiency of this technique. The application of the DDI to fabricate complex colloidal micro- and nanostructures is anticipated. Received: 26 July 2000/Accepted: 5 October 2000     

各向异性金纳米粒子的制备及其在催化中的应用

尽管有关金纳米粒子催化的研究工作很多,但其中大多数都是采用传统的浸渍法将金盐负载到载体上、共沉淀或沉积-沉淀法制得负载的纳米粒子,但这些方法并未吸收最新的纳米技术。最近,金催化剂的研究者开发了在胶态悬浮液中制取金属纳米粒子,然后进行固载,从而使得单金属和双金属催化剂的催化活性和形貌控制取得较大进展。另一方面,最近十年出现了金纳米粒子合成的高级控制技术,得到了许多各向异性的金纳米粒子,且很容易制得新的形貌,可以控制纳米粒子的表面原子配位数和光学特性(可调的等离子体带),这些都与催化密切相关。这些形貌包括纳米棒、纳米星、纳米花、树枝状纳米结构或多面体纳米粒子等。除了高度关注各向异性金纳米粒子的最新开发的制备方法和性质,本综述也清楚地总结了这些纳米粒子独特的催化性能,以及通过提供更高催化性能的金催化剂、控制暴露的活性位,以及热、电和光催化的鲁棒性和可调性,从而给多相催化领域带来令人惊奇的潜在变革。     

The preparation and characterization of poly(o-phenylenediamine)/gold nanoparticles interface for immunoassay by surface plasmon resonance and electrochemistry

The poly-o-phenylenediamine (PoPD) nonconducting film and gold nanoparticles (AuNPs) were combined to fabricate AuNPs/PoPD film, which is used as a novel biocompatible interface for the immobilization of antibody and develop a simple and sensitive label-free immunoassay for the detection of the related antigen (human immunoglobulin G (IgG)). Surface plasmon resonance (SPR) and electrochemical methods were used to provide the real-time information about the polymer film growth, assembling of various sizes of gold nanoparticles, anti-human IgG antibody (anti-hIgG) immobilization and the antigen–antibody interaction. The microstructures of the PoPD and AuNPs/PoPD films were characterized by atomic force microscopy (AFM). These results demonstrated that AuNPs were uniformly dispersed on the porous surface of PoPD film, which formed a nano-structure biocompatible AuNPs/PoPD interface. The use of gold nanoparticles and PoPD film could enhance the immunoassay sensitivity and anti-nonspecific property of the resulting immunoassay electrode. Additionally, the reproducibility and preliminary application of anti-hIgG/AuNPs/PoPD/Au electrode for SPR detection of hIgG was also evaluated.     

Analytical performance of molecular beacons on surface immobilized gold nanoparticles of varying size and density

The high quenching efficiency of metal nanoparticles has facilitated its use as quenchers in molecular beacons. To optimize this system, a good understanding of the many factors that influence molecular beacon performance is required. In this study, molecular beacon performance was evaluated as a function of gold nanoparticle size and its immobilization characteristics. Gold nanoparticles of 4 nm, 15 nm and 87 nm diameter, were immobilized onto glass slides. Each size regime offered distinctive optical properties for fluorescence quenching of molecular dyes that were conjugated to oligonucleotides that were immobilized to the gold nanoparticles. Rigid double stranded DNA was used as a model to place fluorophores at different distances from the gold nanoparticles. The effect of particle size and also the immobilization density of nanoparticles was evaluated. The 4 nm and 87 nm gold nanoparticles offered the highest sensitivity in terms of the change in fluorescence intensity as a function of distance (3-fold improvement for Cy5). The optical properties of the molecular fluorophore was of significance, with Cy5 offering higher contrast ratios than Cy3 due to the red-shifted emission spectrum relative to the plasmon peak. A high density of gold nanoparticles reduced contrast ratios, indicating preference for a monolayer of immobilized nanoparticles when considering analytical performance. Molecular beacon probes were then used in place of the double stranded oligonucleotides. There was a strong dependence of molecular beacon performance on the length of a linker used for attachment to the nanoparticle surface. The optimal optical performance was obtained with 4 nm gold nanoparticles that were immobilized as monolayers of low density (5.7 × 10¹¹ particles cm⁻²) on glass surfaces. These nanoparticle surfaces offered a 2-fold improvement in analytical performance of the molecular beacons when compared to other nanoparticle sizes investigated. The principles developed in this study would assist in the design of solid phase molecular beacons using gold nanoparticles.     

Interaction of gold nanoparticles with mitochondria

Mitochondrion is one of the most important organelles in cells with several vital responsibilities. The consequence of a deficiency in the function of mitochondrion could result with the wide range of diseases and disorders. In this study, we investigated the feasibility of utilizing surface-enhanced Raman scattering (SERS) to understand the mode of interaction of gold nanoparticles (GNPs) with mitochondria. The living lung cancer cells and the isolated mitochondria from these cells were treated with gold colloidal suspension for SERS experiments. The AFM images of the mitochondria confirmed that the treatment did not cause substantial damage to mitochondria. The localization of GNPs in living cells is investigated with confocal microscopy and found that GNPs form aggregates in the cytosol away from the mitochondria. However, SERS spectra obtained from isolated mitochondria and living cells indicate that GNPs escaped from the endosomes or entered into the living cell through another route may be in contact with mitochondria in a living cell. The findings of this study indicate that SERS can be used for mitochondrial research.     

Enhanced detection of gold nanoparticles in agarose gel electrophoresis

Gel electrophoresis is a powerful tool in gold nanoparticle (AuNP) research. While the technique is sensitive to the size, charge, and shape of particles, its optimal performance requires a relatively large amount of AuNP in the loading wells for visible detection of bands. We here describe a novel and more sensitive method for detecting AuNPs in agarose gels that involves staining the gel with the common organic fluorophore fluorescein, to produce AuNP band intensities that are linear with nanoparticle concentration and almost an order of magnitude larger than those obtained without staining the gel.     

Synthesis and spectroscopic characterization of gold nanoparticles

Photoluminescent nanoparticles of gold with size 3, 4, 6, and 9nm are prepared by borohydride/citrate reduction in presence of polyethylene glycol (PEG)/tannic acid. The prepared nanomaterials are characterized by UV-vis spectroscopy and dynamic light scattering (DLS) technique. Intense photoluminescence (PL) is observed in nanoparticles prepared by fast reduction with borohydride in presence of PEG. A red shift of PL emission from 408 to 456nm is observed for the change of size from 4 to 6nm. Increase in PL intensity is observed for all the nanoparticles on the addition of KCl. Citrate reduced gold colloid which consists of large particles of size approximately 35nm with anisotropic shapes showing two plasmon peaks is also prepared. The anisotropy is confirmed by TEM measurement. SERS activity of this colloid is tested using glutamic acid as an adsorbate probe. Assignment of the observed bands is given.     

尺寸可控、高热稳定性有序介孔碳Au催化剂的合成

纳米Au催化剂被认为是具有商业价值的用于醇选择氧化的第二代催化剂.这是因为Au氧化还原电势高,化学稳定性好,可抑制易使Pt族元素中毒的胺等的毒化;其次,对于一些特定选择氧化和还原反应而言,具有较优的反应选择性.目前较多的研究集中在调变Au纳米颗粒与氧化物载体的相互作用,获得协同效应.例如,利用CeO2纳米晶为载体,沉积Au纳米颗粒(约3 nm),使CeO2部分还原为非计量比的催化材料,活化氧并获得高选择氧化性能.碳是相对惰性的载体,与Au相互作用力弱,因此可被用于研究Au纳米颗粒本征催化性能.但负载碳金催化剂在焙烧甚至还原过程中易团聚,且在反应中易流失,可能导致活性下降.利用胶体沉积法可获得介孔碳担载纳米Au催化剂,对葡萄糖选择氧化具有很高的催化活性和选择性.但是,制备中使用的保护剂残留经常被忽略.由于立体效应或电子结构调变作用,保护剂可能影响Au催化剂活性或稳定性.我们前期建立了反应单体参与的自组装技术合成功能化介孔碳路线,一步在介孔碳骨架中掺杂氧化物纳米催化剂.本文从介孔催化材料的结构出发,设计“镶嵌”在碳骨架中的纳米Au颗粒.采用配位作用辅助表面活性剂自组装技术,以苯酚和甲醛为碳前体,引入含巯基硅烷偶联剂,通过配位作用稳定金离子,获得尺寸可控介孔碳限域纳米Au催化剂.低温炭化中,由于巯基-金的配位作用阻抑金属移动或团聚,高温下聚合物炭化为相对刚性的碳骨架.此时,Au纳米颗粒被相邻介孔孔墙限制.硅烷偶联剂可除去,不影响碳载体,并可产生丰富二级孔道,获得多级孔道介孔碳材料.X射线衍射和透射电镜结果显示,所合成的催化剂中Au颗粒的尺寸可控,为3-18nm,且具有单分散性,均匀地分散在整个介孔碳骨架中,其含量为1.1-9.0 wt％.金碳催化剂具有有序的二维六方介孔结构.能量散射谱(EDX)也证明了催化剂只含有C,O和Au元素,没有S和Si元素的残留.X射线光电子能谱(XPS)结果显示催化剂表面的Au含量远远低于ICP的测试结果,也证明了Au纳米颗粒分布在介孔碳骨架内,同时只含有C,O和Au元素也与EDX相符.X射线近边吸收谱结果表明,随着颗粒尺寸的减小,Au表面电子性质发生改变.N2吸脱附等温线显示,有序介孔碳金催化剂具有典型的第Ⅳ型曲线,说明孔径分布范围较窄,主孔道尺寸为3.4-5.7 nm.值得注意的是,低压力段吸附量显示明显突跃,暗示其具有一套约为2 nm的次级介孔.所有的催化剂都具有高的比表面积(1269-1743 m2/g)和大的孔体积(0.79-1.38 cm3/g).Au纳米颗粒具有高的热稳定性,在惰性气氛中,即使在600℃也未见明显聚集长大.进一步讨论了合成中影响金纳米颗粒尺寸的重要影响因素.(1)巯基含量:通过调节巯基组分的含量,可以调控催化剂中Au纳米颗粒的尺寸(9-18 nm).需要强调的是,Au纳米颗粒尺寸与巯基在新合成材料中的浓度有关,当巯基含量在所研究的范围中时(1.55-3.06 mmol/g),Au纳米颗粒尺寸仅仅与巯基浓度有关,而与Au浓度无关.(2)硫酸预炭化处理:新合成的材料经过一步硫酸预炭化处理,可以得到尺寸为3 nm的有序介孔碳金催化剂.表征结果证明,经过硫酸预碳化处理,大量表面活性剂被除去,同时聚合物载体发生部分碳化,有助于在后续高温炭化中保护3 nm金颗粒不团聚.尺寸可控、高热稳定性、无配体保护的有序介孔碳负载Au催化剂有望应用在催化和传感器等领域.     

Physico-chemical characterization and anti-laryngeal cancer effects of the gold nanoparticles

Most recently, gold nanoparticles due to anticancer properties have been considered in medical science. So the aim of the study was green synthesis of gold nanoparticles using Ocimum basilicum extract and its anticancer activity. The prepared Au nanoparticles were characterized by advanced physicochemical techniques like Fourier Transformed Infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX), X-ray Diffraction (XRD) and UV–vis spectroscopy study. It has been established that Au nanoparticles have a spherical shape with a mean diameter from 19 to 44 nm. In the cellular and molecular part of the recent study, the treated cells with Au nanoparticles were assessed by MTT assay for 48 h about the cytotoxicity and anti-human laryngeal cancer properties on normal (HUVEC) and cancer (HEp-2, TU212, KB, UM-SCC-5, UM-SCC-11A and UM-SCC-11B) cell lines. In the antioxidant test, the IC50 of Au nanoparticles and BHT against DPPH free radicals were 228 and 208 µg/mL, respectively. The IC50 of Au nanoparticles were 174, 231, 179, 143, 230, and 216 µg/mL against HEp-2, TU212, KB, UM-SCC-5, UM-SCC-11A and UM-SCC-11B cell lines, respectively. The viability of malignant cell lines reduced dose-dependently in the presence of Au nanoparticles. It appears that the anti-cancer effect of Au nanoparticles e to their antioxidant effects.     

Degradation of polyurethanes in vitro and in vitro: comparison of different models

This study compares and contrasts mechanisms of polyetherurethane (PEU) degradation in vitro and in vivo. Models comprising incubation with hydrogen peroxide in vitro (H₂O₂), in vivo subcutaneous rat implant (SUBQ), and subcutaneous rat cage implant (CAGE) are described and compared with in vivo degradation of the pacemaker lead device retrieved after human implant (PACE). Experimental results support the hypothesis that stress accelerates PEU degradation. Scanning electron microscopy (SEM), gel permeation chromatography (GPC), and Fourier transform IR spectroscopy/attenuated total reflectance (FT-1R/ATR) evaluation of tested PEU samples suggests, for all models, decreased soft segment and increased ester functionality at the polymer surface. These observations are consistent with a single, metal ion catalyzed, polyester intermediate, oxidative degradation mechanism common to all models, and with device performance in vivo. Model comparison suggests that in vitro H₂O₂ and in vivo SUBQ and CAGE models accurately mimic in vivo degradation of the pacemaker lead device (PACE).     

Self-assembly of core-satellite gold nanoparticles for colorimetric detection of copper ions

Molecule-coated nanoparticles are hybrid materials which can be engineered with novel properties. The molecular coating of metal nanoparticles can provide chemical functionality, enabling assembly of the nanoparticles that are important for applications, such as biosensing devices. Herein, we report a new self-assembly of core-satellite gold nanoparticles linked by a simple amino acid l-Cysteine for biosensing of Cu²⁺. The plasmonic properties of core-satellite nano-assemblies were investigated, a new red shifted absorbance peak from about 600 to 800 nm was found, with specific wavelength depending on ratios with assembly of large and small gold nanoparticles. The spectral features obtained using surface-enhanced Raman spectroscopy (SERS) provided strong evidence for the assembly of the Cu²⁺ ions to the L-Cysteine molecules leading to the successful formation of the core-satellite Cu(l-Cysteine) complex on the gold surfaces. In addition, a linear relationship between the concentration of mediating Cu²⁺ and absorbance of self-assembled gold nanoparticles (GNPs) at 680 nm was obtained. These results strongly address the potential strategy for applying the functionalized GNPs as novel biosensing tools in trace detections of certain metal ions.     

金纳米粒子的表面修饰及生物应用进展

近年来纳米材料被广泛应用于生物医学、航空航天和精细化工等领域。构成纳米材料的纳米粒子具有小尺寸效应、表面效应和宏观量子隧道效应等性质。其中金纳米粒子由于其独特的荧光特性、良好的生物相容性和表面等离子共振等性质,被广大科研人员进行深入研究。例如,在生物医学领域,科研人员构建了一系列新型的金纳米比色传感器、光学探针及各类载药体系等。然而,目前金纳米粒子仍存在水分散性差、肾清除效率低和量子发射产率低等问题,限制了其广泛应用。因此,研究人员对金纳米粒子表面进行多样化修饰,从而能有效克服上述缺点。本文就目前主流配体表面修饰金纳米粒子的研究进展进行了详细总结,着重介绍了功能化金纳米粒子在生物成像、生物检测、生物治疗三方面的应用,最后对金纳米粒子的临床治疗机制的探索以及商业化的应用进行了展望,希望能为相关领域的研究者们提供新思路。     

Degradation behaviors of nerve guidance conduits made up of silk fibroin in vitro and in vivo

We have developed a new design of nerve guidance conduits (NGCs) made up of silk fibroin (SF), referred to as SF-NGCs, by a well-established method. The present study aimed to comprehensively investigate the degradation behaviors of SF-NGCs versus SF fibers. After they were allowed to incubate in the protease XIV solution or to be subcutaneously implanted in rabbits, SF-NGCs and SF fibers were subjected to degradation level measurement, mass loss assessment and gel electrophoresis, or light and electron microscopy and mass loss assessment for testing the dynamic course of in vitro or in vivo degradation. The results collectively indicated that SF-NGCs were able to degrade at a significantly increasing rate as compared to SF fibers, thus meeting the requirements of peripheral nerve regeneration. Furthermore, based on the possible involvement pathway in the in vivo degradation of SF-NGCs, the time-dependent changes in the mRNA level of lysosome-related genes (Hip1R, cathepsin D, and tPA) in subcutaneous implantation site within 24-week period post-implantation was determined by real-time RT-PCR, and the resulting data might contribute to our understanding of the molecular aspects that affect in vivo degradation and absorption of SF-NGCs.