绿色木霉菌合成金纳米颗粒的可能性及影响因素

【背景】金纳米颗粒(AuNPs)凭借其稳定性、抗氧化性能和生物相容性在许多领域有广泛应用。目前关于微生物合成金纳米颗粒的研究较少。【目的】对微生物合成金纳米颗粒的可能性以及影响因素进行探究,有利于揭示具体的合成机制,发现AuNPs的特性以及合成位置与菌丝和影响因素的关系。【方法】以绿色木霉菌(Trichoderma viride)菌株(GIM3.141)为菌种资源,通过目视检测法、紫外可见分光光度计、X射线衍射和透射电镜等手段分析合成AuNPs的特征。探讨细胞内生物合成金纳米颗粒(AuNPs)的可能性,研究生物量、初始金离子浓度、溶液pH等因素对细胞内合成AuNPs的影响。【结果】X射线衍射分析表明AuNPs以金纳米晶体形态存在。透射电镜分析表明AuNPs主要位于细胞壁膜间隙,一小部分附着在细胞壁上。紫外可见分光光度计分析表明,金纳米颗粒粒径随着生物量添加量和溶液pH的升高而变小,随着初始金离子浓度的升高而变大。【结论】非致病性真菌绿色木霉菌可以在细胞内合成AuNPs,其中包括伪球形、三角形、四边形和六边形等多种形状,粒径范围从几纳米到三百纳米,为大规模、低成本、无污染地生物合成纳米颗粒工艺提供了菌种资源。     

Trichosporon montevideense WIN合成纳米金的催化特性

【目的】考察菌株Trichosporon montevideense WIN合成纳米金的催化特性及应用。【方法】利用活性WIN菌作用不同浓度HAu Cl_4(1、2和4 mmol/L)合成纳米金的特性,分别利用活性WIN菌和灭活WIN菌合成纳米金,分析合成纳米金的形貌、粒径及其催化特性。【结果】HAu Cl_4浓度为1 mmol/L时,菌株WIN合成了纳米金,HAu Cl_4浓度为2 mmol/L和4 mmol/L时,菌株WIN合成了纳米金及较大尺寸的金颗粒。通过紫外-可见光谱扫描、透射电子显微镜分析,发现活性和灭活WIN菌均能还原Au~(3+)合成纳米金,合成的纳米金均以球形为主,还有少量三角形、四边形及六边形。活性WIN菌合成的纳米金粒径范围为3 nm-252 nm,平均粒径为45.2 nm,而灭活WIN菌合成的纳米金为1 nm-271 nm,平均粒径为38.3 nm。活性和灭活WIN菌合成的纳米金对还原4-硝基苯酚的催化速率分别为2.76×10~(-3)s~(-1)和4.84×10~(-3)s~(-1)。【结论】菌株Trichosporon montevideense WIN的活性及灭活细胞均可以合成纳米金,且合成的纳米金具有良好的催化特性,在催化去除环境中难降解污染物中具有一定的应用前景。     

牛血清蛋白与纳米金颗粒相互作用的研究

为了研究纳米颗粒与蛋白质的相互作用原理,我们选取纳米金颗粒及牛血清蛋白为材料,通过牛血清蛋白与纳米金颗粒的物理吸附作用,结合蛋白酶K酶切、SDS洗脱以及SDS-聚丙烯酰胺凝胶电泳检测的方法,我们了解到,纳米颗粒与蛋白质的结合主要是由蛋白质中的某一段特定的序列结合在纳米颗粒的表面所导致的,该结果的发现不仅对纳米颗粒在生物体内广泛的应用奠定了理论基础,对功能性纳米颗粒在生物体内功能的发挥也是至关重要的。     

金纳米棒的光学性质及其在生物医学领域的应用

简要介绍金纳米棒的光学性质和合成方法,重点阐述其在生物医学领域研究的最新进展,并对其今后的研究方向进行展望．金纳米棒是一种胶囊状的金纳米颗粒,具有一个横向等离子共振吸收峰和一个纵向等离子共振吸收峰,分别对应其横轴和纵轴两个特征尺寸．通过调节金纳米棒的长径比,纵向等离子共振吸收峰可由可见光区跨越至近红外光区．金纳米棒这一独特的光学性质在生物和化学传感方面有着广泛而重要的应用前景．     

基于纳米金光学性质的分子检测与应用

纳米金颗粒是近年研究最为广泛的纳米材料之一,它具有良好的生物相容性、化学稳定性以及独特的光学性质,在生物分子检测、诊断和治疗方面具有很大的发展潜力。尤其是纳米金显示出特殊的表面等离子体共振现象,导致了粒子表面产生强电磁场,并最终增强了诸如吸收和散射的辐射特性,其散射光强与粒子的尺寸和团聚状态有密切关系。而由于共振现象而产生的纳米金对光的强烈吸收并高效转换为热效应也被用于检测和治疗。此外,与纳米金尺寸相关的局域表面等离子体共振光学特性,能够在粒子附近产生很强的电磁场增强,从而构成表面增强拉曼散射的基础。纳米金在强光照射下也表现出良好的抗光漂白的荧光现象,其特有的荧光寿命也成为检测的一种有效手段。与其他荧光物质作用时,又表现出表面增强荧光特性以及荧光共振能量转移。综述中,在介绍纳米金这些特殊光学性质的基础上,回顾了其在生物分子检测方面的应用进展。     

微生物应用于纳米生物合成技术研究进展

基于发展纳米材料"绿色合成技术"重要性,生物合成纳米材料已成为纳米合成技术研究热点。微生物具有廉价、易培养、繁殖快等优点被应用于多种纳米材料的生物合成研究,成为生物合成纳米材料的重要生物类群。本文综述了细菌、放线菌、酵母菌以及真菌等微生物应用于纳米生物合成技术的发展;着重评述了纳米材料微生物合成生物方法、纳米材料微生物合成相关机制、纳米材料形貌和尺寸微生物调控合成方法以及应用研究进展;并对纳米材料微生物合成技术未来发展趋势进行了展望。     

纳米颗粒与生物大分子的相互作用及其生物毒性机制

纳米颗粒已得到广泛的应用,同时其潜在的毒性及生物学效应也引起了广泛的关注。许多文献证实纳米颗粒对生物体具有毒性作用,但在分子水平上对其毒性机制的研究较少。本文对近年来纳米颗粒与生物大分子相互作用的最新研究进行了综述,包括纳米颗粒与蛋白质、脂类、核酸等生物分子间的相互作用。     

基于微生物生物合成纳米颗粒机制的研究进展

纳米粒子的合成方法多种多样,包括物理法、化学法和生物合成法,其中生物合成法是以生物为基体的绿色合成方法。由于微生物易于培养、生长快、廉价易得,已成为纳米粒子生物合成法的重要生物类群。微生物和纳米材料的多样性决定了其合成机制的多样化。本文结合国内外的科研报道,着重介绍了目前纳米粒子生物合成机制,并对纳米粒子微生物合成技术未来发展趋势进行了展望。     

生物脱氮中工程纳米颗粒的毒害作用及减毒措施的研究进展

氮化合物在生命代谢过程中扮演着重要的角色,但过多的无机氮会导致水体恶化进而影响人类健康,生物脱氮技术可高效去除环境中的无机氮且不引起二次污染。随着工程纳米颗粒在生活中的广泛应用,导致其大量释放到土壤及水体中,极大地阻碍了废水处理中的生物脱氮过程,因此,微生物脱氮过程中工程纳米颗粒的毒害作用及减毒措施成了近年来的研究热点。阐述了工程纳米颗粒进入水环境的方式,系统分析了工程纳米颗粒对废水处理系统和生物脱氮过程的影响,详细说明了工程纳米颗粒对脱氮微生物的毒害作用、脱氮微生物的抵御机制及减毒措施,并对未来的研究趋势进行了展望。旨为提高工程纳米颗粒存在条件下的脱氮效率具有重要的理论指导意义,同时,可促进工程纳米颗粒对耐冷异养硝化和好氧反硝化菌的毒害及应激机制研究。     

生物条形码检测技术及其研究进展

生物条形码检测技术作为一种新的诊断工具,已逐渐应用于蛋白质、核酸和小分子物质的检测。生物条形码技术通过构建"纳米金颗粒-目标物-磁纳米颗粒"三明治结构,利用磁场作用,将结合在纳米金颗粒表面的大量相同序列的寡聚核苷酸洗脱下来,并进一步放大信号,实现对目标物的间接或直接检测。本文介绍了生物条形码检测技术的原理及其应用,综述了生物条形码与生物芯片银染技术、酶标纳米金技术、生物传感器技术、微孔板银染技术以及聚合酶链式反应技术等高灵敏放大信号技术的联合应用;并对其前景进行了展望,探索其最佳反应条件、优化操作步骤和多种物质的残留检测,开发标准化、商业化的生物条形码检测技术免疫试剂盒是未来重要的研究方向。     

Current state and prospects of the phytosynthesized colloidal gold nanoparticles and their applications in cancer theranostics

The design, development, and biomedical applications of phytochemical-based green synthesis of biocompatible colloidal gold nanoparticles (AuNPs) are becoming an emerging field due to several advantages (safer, eco-friendly, simple, fast, energy efficient, low-cost, and less toxic) over conventional chemical synthetic procedures. Biosynthesized colloidal gold nanoparticles are remarkably attractive in several biomedical applications including cancer theranostics due to small size, unusual physico-chemical properties, facile surface modification, high biocompatibility, and numerous other advantages. Of late, several researchers have investigated the biosynthesis and prospective applications (diagnostics, imaging, drug delivery, and cancer therapeutics) of AuNPs in health care and medicine. However, not a single review article is available in the literature that demonstrates the anti-cancer potential of biosynthesized colloidal AuNPs with detailed mechanistic study. In the present review article, we for the first time discuss the biointerface of colloidal AuNPs, plants, and cancer mainly (i) comprehensive mechanistic aspects of phytochemical-based synthesis of AuNPs; (ii) proposed anti-cancer mechanisms along with biomedical applications in diagnostics, imaging, and drug delivery; and (iii) key challenges for biogenic AuNPs as future cancer nanomedicine.

     

Biogenic synthesis of gold nanoparticles by marine endophytic fungus-Cladosporium cladosporioides isolated from seaweed and evaluation of their antioxidant and antimicrobial properties

Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetra id="spar0060">Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetic industries. In the present study, we have optimized a method for biogenic synthesis of gold nanoparticles (AuNPs) from Cladosporium cladosporioides, an endophytic fungus of the seaweed, Sargassumwightii. The identity of the fungus was established by the 18 s rRNA and ITS sequence. The AuNPs synthesized using C. cladosporioides were characterized by UV–vis spectrophotometer, Field Emission Scanning Electron Microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Dynamic light scattering, Atomic force microscopy, and Energy dispersive X-ray spectroscopic studies. They were tested for free radical scavenging activity (DPPH and FRAP assay) and antimicrobial activity against a panel of pathogenic microorganisms. The AuNps were within 100 nm as confirmed by the above methods. An attempt was made to understand the mechanism of the gold nanoparticle synthesis using the fungal extract. The present study shows the involvement of NADPH-dependent reductase and phenolic compounds in the bioreduction of the gold metal salts to nanoparticles. The AuNPs showed significant antioxidant as well as the antimicrobial activity. Hence, this study has shown a great potential for the development of a cost effective antimicrobial treatment utilizing biogenic gold nanoparticles.     

Charge dependence of ligand release and monolayer stability of gold nanoparticles by biogenic thiols

The effect of surface charge on the stability of gold nanoparticles (AuNPs) to the biogenic thiols glutathione (GSH), dihydrolipoic acid (DHLA), and cysteine was quantified. It was observed that the rate of release of fluorescein-tagged ligand was determined by the surface charge of the AuNPs, with cationic particles much more labile than anionic analogues. This ability to tune stability is significant for the design of both delivery vehicles and intracellular probes.     

Intracellular Synthesis of Gold Nanoparticles Using an Ectomycorrhizal Strain EM-1083 of <Emphasis Type="Italic">Laccaria fraterna</Emphasis> and Its Nanoanti-quorum Sensing Potential Against <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis>

In this research work different shapes and sizes of gold nanoparticles (AuNPs) were synthesized through an intracellular biogenic approach, exploiting the chloroauric acid reducing and Au⁰ stabilizing potential of Laccaria fraterna EM-1083 mycelia. The intracellularly synthesized AuNPs exhibits anti-quorum sensing inhibitory potential against Pseudomonas aeruginosa. The synthesized AuNPs were characterized using UV–visible spectroscopy; transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The characterization proved that the successful synthesis of highly stable crystalline AuNPs with various shapes. Here we tested inhibitory activity of AuNPs on QS-regulated biofilm development and pyocyanin production traits of P. aeruginosa. The qualitative and quantitative data demonstrated that AuNPs significantly inhibited the biofilm formation and pyocyanin production. In summary, our results signify the future use of intracellularly synthesized AuNPs in P. aeruginosa mediated diseases.     

Targeting of ovarian cancer cell through functionalized gold nanoparticles by novel glypican-3- binding peptide as a ultrasound contrast agents

Gold nanoparticles (AuNPs) are widely studied nanomaterials for their potential employment in advanced biomedical applications, such as selective molecular imaging and targeted drug delivery. AuNPs are generally low cost and highly biocompatible, can be easily functionalized with a wide variety of functional ligands, and have been demonstrated to be effective in enhancing ultrasound contrast at clinical diagnostic frequencies. Therefore, AuNPs might be used as contrast agents in echographic imaging. In this work, we have developed a AuNPs -based system for the in vitro molecular imaging of ovarian carcinoma cells that express high levels of glypican-3 protein (GPC-3) on their surface. In this regard, a novel GPC-3 targeting peptide was designed and conjugated to fluorescent AuNPs nanoparticles. The physicochemical properties, acoustic behavior, and biocompatibility profile of the functionalized AuNPs were characterized. Then, the binding and uptake of both naked and functionalized AuNPs were analyzed by laser scanning confocal microscopy in human HeLa cells (ovarian carcinoma) cell line. The results obtained showed that GPC-3-functionalized fluorescent AuNPs significantly enhanced the ultrasound contrast and were effectively bound and taken up by HeLa cells without affecting their viability.     

Green synthesis of gold nanoparticles by a newly isolated strain <Emphasis Type="Italic">Trichosporon</Emphasis><Emphasis Type="Italic">montevideense</Emphasis> for catalytic hydrogenation of nitroaromatics

Objective

To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics.

Results

AuNPs had a characteristic absorption maximum at 535 nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12 nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1 mM) by NaBH₄ had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39 min^?1 with addition of 1.45 × 10^?2 mM AuNPs.

Conclusions

An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.

     

Gold nanoparticle-based signal amplification for biosensing

Colloidal gold nanoparticles (AuNPs), with unique properties such as highly resonant particle plasmons, direct visualization of single nanoclusters by scattering of light, catalytic size enhancement by silver deposition, conductivity, and electrochemical properties, are very attractive materials for several applications in biotechnology. Furthermore, as excellent biological tags, AuNPs can be easily conjugated with biomolecules and retain the biochemical activity of the tagged biomolecules, making AuNPs ideal transducers for several biorecognition applications. The goal of this article is to review recent advances of using AuNPs as labels for signal amplification in biosensing applications. We focus on the signal amplification strategies of AuNPs in biosensing/biorecognition, more specifically, on the main optical and electrochemical detection methods that involve AuNP-based biosensing. Particular attention is given to recent advances and trends in sensing applications.     

Analytical potential of gold nanoparticles in functional aptamer-based biosensors

Gold nanoparticles (AuNPs) exhibit many predominant capabilities such as high biocompatibility, chemical stability, strong localized surface plasmon resonance absorption, and high extinction coefficient in the visible region. These properties have enabled the extensive use of AuNPs in optical and electrochemical biosensors. As a kind of functional nucleic acids, aptamers can be considered as a valid alternative to antibodies or other bio-receptors and have been widely employed to develop novel biosensors. We are summarizing here the state of the art of AuNP-based biosensors that use functional aptamers as molecular recognition elements. In many cases, AuNPs themselves can be used as a probe for detection, such as various colorimetric aptasensors and fluorescent aptasensors. They also can be used as probe vectors to enlarge detection signals and to increase the number of conceivable substrates in electrochemical aptasensors.     

A Bacteriophage Mediated Gold Nanoparticles Synthesis and Their Anti-biofilm Activity

In the present study, gold nanoparticles (AuNPs) synthesis was carried out by using a rare bacteriophage which is morphologically similar to 7–11 phages of the C3 morphotype of tailed phage belonging to Podoviridae family as green route. Effect of various physiological parameters like pH, temperature and concentration of gold chloride salt on AuNPs synthesis was studied. The reaction mixtures have shown vivid colours at various physiological parameters. Phage inspired AuNPs were further characterized by using different techniques such as UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and dynamic light scattering (DLS). DLS study revealed synthesis of various sizes of AuNPs in the range of 20–100 nm. SEM studies revealed synthesis of varied shaped AuNPs, viz., spheres, hexagons, triangles, rhomboids and rectangular etc. The presence of Au in the nanostructures was confirmed by EDS. The XRD pattern reflects the crystalline nature and nano size of AuNPs. These phage inspired AuNPs showed anti-bacterial activity against different bacterial pathogens. Anti-biofilm activity of AuNPs was evaluated on a glass slide. It was noticed that at 0.2 mM concentration of these AuNPs about 80% of biofilm formation by Pseudomonas aeruginosa, a human pathogen was inhibited. Thus, the phage inspired AuNPs synthesis could be potential therapeutic agents against human pathogens.     

Aqueous zymography screening of matrix metalloproteinase activity and inhibition based on colorimetric gold nanoparticles

An optical gold nanoparticles (AuNPs)-based method was fabricated for the rapid detection of matrix metalloproteinase (MMP) activity and screening potential MMP inhibitors without sophisticated instruments. The diagnosis platform was composed of AuNPs, particular MMP substrates and 6-mercapto-1-hexanol (MCH). The functionalized AuNPs were subjected to specific MMP digestion, and the MMP found the substrate on AuNPs, such that the AuNPs lost shelter and MCH increased the attraction force between AuNPs. Consequently, AuNPs aggregation and a color change from red to purple with increasing MMP concentration were observed. The surface plasmon resonance (SPR) of the formed AuNPs allowed for the quantitative detection of MMP activity. A sensitive linear correlation existed between the absorbance and the activity of the MMPs, which ranged from 10 ng/mL to 700 ng/mL in NTTC buffer and plasma samples. The proposed colorimetric method could be accomplished in a homogeneous solution with one-step operation in 30 min and has been successfully applied to the determination of particular MMP activity in plasma samples, in which the results are consistent with substrate zymography. This technology may become a simple platform for parallel screening a number of inhibitors and offer an alternative method to studying the efficiency of inhibitors for suppressing MMP activity. The absorbance ratio at 625 nm and 525 nm (A(625)/A(525)) confirmed the efficiency of the inhibitors as observed in substrate zymography. The IC(50) of ONO-4817 and galardin for MMP-1, MMP-2 and MMP-7 determined by the proposed colorimetric method was similar to the results of substrate zymography.