Biogenic synthesis of gold nanoparticle using fractioned cellular components from eukaryotic algae and cyanobacteria

In the present investigation fractioned cellular components like intact pigment bearing thylakoids/chloroplasts, carotenoids, protein, polysaccharides were extracted from the cyanobacterium Anabaena sphaerica and green alga Chlorococcum infusionum. Each of these extracts was used separately in search for efficient reducing agents during gold nanoparticle (GNP) production in pro‐ and eukaryotic algal cell systems. The whole biomass and extracted compounds or cellular structures were exposed in 25 mg L^?1 aqueous hydrogen tetrachloroaurate solutions separately at room temperature. Isolated viable chloroplasts from C. infusionum and thylakoids from A. sphaerica were found to be able to reduce gold ions. The protein extracts of both strains were also able to synthesize GNP at 4°C. Extracted polysaccharides of the two strains responded differently. Polysaccharides from A. sphaerica showed positive response in GNP synthesis, whereas no change was observed for C. infusionum. The carotenoids extracts from both strains acted like an efficient reducing agent. Initially the reducing efficiency of these extracted components was confirmed by the appearance of purple color in biomass or in experimental media. The GNPs, synthesized within the biomass were extracted by sonication with sodium citrate. The UV–vis spectroscopy of extracted purple colored suspensions and media showed the absorption bands at approximately 530–540 nm indicating a strong positive signal of GNP synthesis. Transmission electro n microscopy determined the size and shapes of the particles. The X‐ray diffraction study of the synthesized GNP revealed that the 2θ values appeared at 38.2°, 44.5°, 64.8° and 77.8°. Amongst all, isolated thylakoids and chloroplast showed only spherical GNP production with variable size range at pH 4. Monodisperse GNPs were also synthesized by isolated thylakoids and chloroplast at pH 9. A detailed morphological change of gold treated biomass was revealed employing scanning electron microscopy. The fluorescent property of gold loaded cells was studied by fluorescence microscopy.     

Synthesis of intracellular and extracellular gold nanoparticles with a green machine and its antifungal activity

Green synthesis method is being increasingly used in the development of safe, stable, and eco-friendly nanostructures with biological resources. In this study, extracellular and intracellular synthesis of gold nanoparticles (AuNPs) was carried out using green algae Chlorella sorokiniana Shihira & R.W. Fresh algae were isolated and identified from Musaözü Pond located in the province of Eskişehir and then extraction process were performed. Optimization studies were studied using pH value, metal salt concentration, and time parameters for extracellular synthesis and using only time parameter for intrasellular synthesis. Since more controlled and optimum conditions can be achieved in the production of AuNPs by extracellular synthesis, these nanoparticles (NPs) were used for characterization and antifungal activity studies. Optical, physical, and chemical properties of synthesized NPs were characterized by UV visible spectrophotometer (UV-Vis), dynamic light scattering (DLS), Zetasizer, X-Ray diffraction (XRD), Fourier transform ınfrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), ınductively coupled plasma mass spectrometer (ICP-MS) and transmission electron microscope (TEM) analysis. The optimum conditions for AuNPs synthesis were determined as 1 mM for HauCl₄ concentration, 6 for pH value, and 60th min for time. AuNPs obtained from extracellular synthesis from C. sorokiniana extract are 5–15 nm in size and spherical shape. TEM images of extracellular synthesis show noticeable cell wall and membrane damages, cytoplasma dissolutions, and irregularities. AuNPs obtained by intracellular synthesis are in 20–40 nm size and localized in the cell wall and cytoplasm. These NPs exhibited significant antifungal activity against C. tropicalis, C. glabrata, and C. albicans isolates. AuNPs obtained by algae-mediated green synthesis have a significant potential for medical and industrial use, and this eco-friendly synthesis method can be easily scaled for future studies.     

Biosurfactants as green stabilizers for the biological synthesis of nanoparticles

Taking into consideration the needs of greener bioprocesses and novel enhancers for synthesis using microbial processes, biosurfactants, and/or biosurfactant producing microbes are emerging as an alternate source for the rapid synthesis of nanoparticles. A microemulsion technique using an oil-water-surfactant mixture was shown to be a promising approach for nanoparticle synthesis. Biosurfactants are natural surfactants derived from microbial origin composed mostly of sugar and fatty acid moieties, they have higher biodegradability, lower toxicity, and excellent biological activities. The biosurfactant mediated process and microbial synthesis of nanoparticles are now emerging as clean, nontoxic, and environmentally acceptable “green chemistry’’ procedures. The biosurfactant-mediated synthesis is superior to the methods of bacterial- or fungal-mediated nanoparticle synthesis, since biosurfactants reduce the formation of aggregates due to the electrostatic forces of attraction and facilitate a uniform morphology of the nanoparticles. In this review, we highlight the biosurfactant mediated synthesis of nanoparticles with relevant details including a greener bioprocess, sources of biosurfactants, and biological synthesized nanoparticles based on the available literature and laboratory findings.     

Green synthesis and characterization of bisphosphonate conjugated gold nanoparticle with Asparagus racemosus root extract

Bisphosphonates improve orthodontic anchorage. More targeted action of this drug can be achieved through its conjugation with gold nanoparticles. Asparagus racemosus is a green edible medicinal plant used in Ayurvedic preparations to treat aging, vigor, immunity, longevity, and skeletal issues. Therefore, it is of interest to report the green synthesized Bisphosphonate conjugated gold nanoparticles with Asparagus racemosus extract and to characterize them.     

Recycling and adaptation of Klebsormidium flaccidum microalgae for the sustained production of gold nanoparticles

Targeting the development of cell-based bioreactors for the production of metal nanoparticles, the possibility to perform the sustained synthesis of colloidal gold using Klebsormidium flaccidum green algae was studied. A first strategy relying on successive growth/reduction/reseeding recycling steps demonstrated maintained biosynthesis capability of the microalgae but limitation in metal content due to toxic effects. An alternative approach consisting of progressive gold salt addition revealed to be suitable to favor cell adaptation to larger metal concentrations and supported particle release over month periods.     

Characterization and application of porous gold nanoparticles as 2‐photon luminescence imaging agents: 20‐fold brighter than gold nanorods

Two‐photon nonlinear microscopy with the aid of plasmonic contrast agents is an attractive bioimaging technique capable of generating high‐resolution images in 3 dimensions and facilitating targeted imaging with deep tissue penetration. In this work, physically synthesized gold nanoparticles containing multiple nanopores are used as 2‐photon contrast agents and are reported to emit a 20‐fold brighter 2‐photon luminescence as compared to typical contrast agents, that is, gold nanorods. A successful application of our porous gold nanoparticles is experimentally demonstrated by in vitro nonlinear optical imaging of adipocytes at subcellular level.      

Antibiofilm and antimicrobial activities of green synthesized silver nanoparticles using marine red algae Gelidium corneum

In our study, green synthesis of silver nanoparticles was carried out using a red algae Gelidium corneum extract as reducing agent. The obtained silver nanoparticles were characterized by UV–vis, TEM, XRD, FTIR and ICP-MS measurements. FTIR measurements indicated the possible functional groups responsible for the stabilization and reduction of nanoparticles, while XRD analysis results explained the crystalline structure of the particles with centric cubic geometry. TEM micrographs showed that the size of the nanoparticles was between 20–50 nm. According to the broth microdilution test results, AgNPs showed a high antimicrobial activity with very low MIC values (0.51 μg/ml for Candida albicans yeast and 0.26 μg/ml for Escherichia coli bacteria). The different ultrastructural effects of silver nanoparticles on yeast and bacterial cells were observed by TEM. Antibiofilm efficacy studies were also examined in two stages as prebiofilm and postbiofilm effect. In prebiofilm effect studies, AgNPs (0.51 μg/ ml) exhibited 81% reducing effect on biofilm formation. The highest reduction rate in postbiofilm studies was 73.5% and this was achieved with 2.04 μg/ml AgNPs. Our data support that the silver nanoparticles obtained by this environmentally friendly process have potential to be used for industrial and therapeutic purposes.     

Back Cover: Characterization and application of porous gold nanoparticles as 2‐photon luminescence imaging agents: 20‐fold brighter than gold nanorods (J. Biophotonics 2/2018)

Gold nanoparticles serve as imaging contrast agents useful for two‐photon nonlinear microscopy of biological cells and tissues. In this study, 100‐nm‐sized gold particles with a multitude of nanopores embedded inside have been physically synthesized and investigated for the plasmonic enhancement in two‐photon luminescence. Exhibiting remarkable potential for two‐photon imaging, the porous gold nanoparticles boost near‐infrared light absorption substantially and allow emission signals 20 times brighter than gold nanorods being currently used as typical imaging agents. Further details can be found in the article by Joo H. Park et al. ( e201700174 )

     

In vitro and in vivo anticandidal efficacy of green synthesized gold nanoparticles using Spirulina maxima polysaccharide

This study, for the first time, demonstrated an unprecedented approach for the green synthesis of gold (Au) nanoparticles (NPs) using the polysaccharide of Spirulina maxima as a reducing agent. Time-kill kinetic analysis was used to evaluate the antifungal activity of the green synthesized Au NPs against the pathogenic Candida albicans (C. albicans). The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were found to be 32 μg/mL and 64 μg/mL, respectively. Ultra-structural analysis indicated prominent damage on cell wall of the C. albicans after Au NPs treatment, and suggested that the treatment could increase the membrane permeability and disintegration of cells leading to cellular death. The results of propidium iodide (PI) uptake assay showed the higher level of cell death in Au NPs treated C. albicans cells, further confirming the loss of plasma membrane integrity. Cytotoxicity analysis of Au NPs on HEK293T and A549 cells showed no cytotoxic effect up to 64 μg/mL of Au NPs concentration, indicating the potential use in in vivo studies. Also, the recovery of C. albicans infected zebrafish after Au NPs therapy suggest green synthesized Au NPs from S. maxima polysaccharide as a prospective anticandidal agent.     

CeO2 nanoparticles synthesized through green chemistry are biocompatible: In vitro and in vivo assessment

Widespread use of cerium oxide (CeO₂) nanoparticles (NPs) is found in almost all areas of research due to their distinctive properties. CeO₂ NPs synthesized via green chemistry have been characterized for antioxidant, phytochemical, and biological potential. Physical characterization through scanning electron microscopy, XRD, and TGA showed that the NPs are circular in shape, 20‐25 nm in size, and stable in a wide range of temperature. NPs display significant antioxidant (32.7% free radical scavenging activity) and antileishmanial (IC₅₀ 48 µg mL^?1) properties. In vitro toxicity tested against lymphocytes verified that NPs are biocompatible (99.38% viability of lymphocytes at 2.5 μg mL^?1). In vivo toxicity experiments showed no harmful effects on rat serum chemistry and histology of various organs and did not even change the concentration of antioxidative enzymes, total protein contents, lipid peroxidation, and nitrosative stress. These observations are in line with the statement that plant‐based synthesis of CeO₂ NPs lessens or nullifies in vitro and in vivo toxicity and hence CeO₂ NPs are regarded as a safe and biocompatible material to be used in drug delivery.     

Molecular recognition between insulin and dextran encapsulated gold nanoparticles

Insulin is a peptide hormone that can regulate the metabolism of carbohydrates and lipids. This hormone is closely related to glucose‐uptake in cells and can control blood glucose levels. Dextran is a polysaccharide composed of glucose units. In this study, we discovered that dextran‐encapsulated gold nanoparticles (AuNPs@Dextran) and nanoclusters (AuNCs@Dextran) can be used to recognize insulin. The dissociation constant of insulin toward AuNPs@Dextran was estimated to be ～5.3 × 10^?6 M. The binding site on insulin toward the dextran on the nanoprobes was explored as well. It was found that the sequence of numbers 1–22 on the insulin B chain can interact with the dextran encapsulated nanoprobes. Additionally, we also demonstrated that the dextran‐encapsulated nanoprobes could be used as concentration probes to selectively enrich trace amounts of insulin (～1 pM) from serum samples. Copyright © 2016 John Wiley & Sons, Ltd.     

Polar cyanobacteria versus green algae for tertiary waste-water treatment in cool climates

Forty-nine strains of filamentous, mat-forming cyanobacteria isolated from the Arctic, subarctic and Antarctic environments were screened for their potential use in outdoor waste-water treatment systems designed for cold north-temperate climates. The most promising isolate (strain E18, Phormidium sp. from a high Arctic lake) grew well at low temperatures and formed aggregates (flocs) that could be readily harvested by sedimentation. We evaluated the growth and nutrient uptake abilities of E18 relative to a community of green algae (a Chlorococcalean assemblage, denoted Vc) sampled from a tertiary treatment system in Valcartier, Canada. E18 had superior growth rates below 15°C Canada. (μ = 0.20 d-¹ at 10°C under continuous irradiance of 225 μmol photon m-² s-¹) and higher phosphate uptake rates below 10°C (k = 0.050 d-¹ at 5°C) relative to Vc (μ=0.087 d-¹ at 10°C and k = 0.020 d-¹ at 5°C, respectively). The green algal assemblage generally performed better than E18 at high temperatures (at 25°C, μ = 0.39 d-¹ and k = 0.34 d-¹ for Vc; μ = 0.28 d-¹ and k = 0.33 d-¹ for E18). However, E18 removed nitrate more efficiently than Vc at most temperatures including 25°C. Polar cyanobacteria such as strain E18 are appropriate species for waste-water treatment in cold climates during spring and autumn. Under warmer summer conditions, fast-growing green algae such as the Vc assemblage are likely to colonize and dominate, but warm-water Phormidium isolates could be used at that time. This revised version was published online in August 2006 with corrections to the Cover Date.     

响应性聚集金纳米粒子体系用于细菌的体外热疗研究

目的利用发生响应性聚集后的金纳米粒子体系的较强的光热特性,研究其对细菌的体外光热杀伤作用。方法通过Au-S键反应将合成好的多肽A和多肽B分别修饰到金纳米粒子(GNPs)表面,然后等比例混合组成GNPssystem。首先利用动态光散射(DLS)和透射电镜(TEM)研究其在弱酸性条件下的响应性聚集情况,利用多功能酶标仪研究其在在弱酸性条件下的紫外吸收变化;然后为了了解该纳米粒子在菌液中的光热转换情况,分别测定其在弱酸性条件下溶液内和与细菌作用后的温度变化曲线;进一步考察其体外抗菌效果。结果DLS检测到合成的GNPssystem在弱酸性条件下粒径由16nm增大到900nm左右,并在TEM下可见明显的聚集体,并且在650~900nm的紫外吸收信号明显增高。在模拟细菌的弱酸性环境下,GNPssystem在激光照射条件下均实现了溶液和细菌混合溶液的快速升温,且最高温度可达69.8℃,与对照组GNPs-PEG2000相比具有显著的统计学差异;体外抗菌实验结果显示,GNPssystem对金黄色葡萄球菌的杀伤力最强,50μg/mL浓度时就可杀死约50%的细菌;浓度为200μg/mL时基本上可以完全杀死,与对照组GNPs-PEG2000相比较具有显著的统计学差异。结论本研究为GNPs的设计提供了新的思路,为GNPs用于光热治疗提供了新的方法。     

纳米金探针在基因检测中的应用

传统的核酸分析中常采用放射性元素、荧光色素以及酶标记等基因探针,这些探针都存在着一些不足之处。近年来,纳米金探针作为一种新型的基因探针,己引起了广泛的关注。该探针具有优良的光谱特征和光化学稳定性,对核酸的非特异吸附性小,与核酸等生物大分子结合后不改变生物分子的活性。将纳米金探针用于基因检测,具有操作简便、快速、安全、实验成本低等优点。本文就纳米金探针的发展过程、纳米金探针的制备、检测原理及其在基因分析中的应用等几个方面作了系统而全面地概述,同时介绍了纳米金探针的最新研究进展,并对其发展前景作了简要评述。     

Fluorescence life‐time imaging and steady state polarization for examining binding of fluorophores to gold nanoparticles

Nanocomposites as multifunctional agents are capable of combing imaging and cell biology technologies. The conventional methods used for validation of the conjugation process of nanoparticles (NPs) to fluorescent molecules such as spectroscopy analysis and surface potential measurements, are not sufficient. In this paper we present a new and highly sensitive procedure that uses the combination of (1) fluorescence spectrum, (2) fluorescence lifetime, and (3) steady state fluorescence polarization measurements. We characterize and analyze gold NPs with Lucifer yellow (LY) surface coating as a model. We demonstrate the ability to differentiate between LY‐GNP (the conjugated complex) and a mixture of coated NP and free dyes. We suggest the approach for neuroscience applications where LY is used for detecting and labeling cells, studying morphology and intracellular communications.

Histograms of Fluorescence lifetime imaging (FLIM) of free LY dye (Left) in comparison to the conjugated dye to gold nanoparticles, LY‐GNP (Middle) enable the differentiation between LY‐GNP (the conjugated complex) and a mixture of coated NP and free dyes (Right).     

Advances and potential application of gold nanoparticles in nanomedicine

Nanomedicine is an emerging research area which has brought new possibilities and promising applications in image, diagnosis, and treatment. Nanoparticles (NPs) for medicinal purposes can be made of several material types such as silica, carbon, different polymers, and metals as silver, copper, titanium, and gold. Gold NPs (AuNPs) are the most studied and used, mostly due to their characteristics including simple preparation, controllable size and distribution, biocompatibility, good acceptance of surface modifications, and specific surface plasmon resonance (SPR). This study reviews the scientific literature regarding the potential applications of AuNPs in the development of new diagnostic and therapeutic strategies for nanomedicine, including their biomedical use as a drug carrier, as an agent in radio and phototherapy, and bioimaging for image diagnosis. While it becomes clear that much research remains to be done to improve the use of these nanoparticles, with particular concern for safety issues, the evidence from the literature already points to the great potential of AuNPs in nanomedicine.     

Bioaccumulation and toxicity of gold nanoparticles after repeated administration in mice

Gold nanoparticles (GNPs) offer a great promise in biomedicine. Currently, there is no data available regarding the accumulation of nanoparticles in vivo after repeated administration. The purpose of the present study was to evaluate the bioaccumulation and toxic effects of different doses (40, 200, and 400 μg/kg/day) of 12.5 nm GNPs upon intraperitoneal administration in mice every day for 8 days.The gold levels in blood did not increase with the dose administered, whereas in all the organs examined there was a proportional increase on gold, indicating efficient tissue uptake. Although brain was the organ containing the lowest quantity of injected GNPs, our data suggest that GNPs are able to cross the blood-brain barrier and accumulate in the neural tissue. Importantly, no evidence of toxicity was observed in any of the diverse studies performed, including survival, behavior, animal weight, organ morphology, blood biochemistry and tissue histology. The results indicate that tissue accumulation pattern of GNPs depend on the doses administered and the accumulation of the particles does not produce sub-acute physiological damage.     

靶向金纳米棒对隐球菌活性影响的体外实验研究

目的：设计对隐球菌荚膜特异性标记的靶向金纳米棒,研究靶向金纳米棒的体外光热作用对隐球菌活性的影响。方法晶种生长法制备金纳米棒,偶联隐球菌荚膜抗体,检测表征,与隐球菌体外孵育,近红外激光照射,检测隐球菌活性变化。结果成功制备与荚膜抗体偶联的金纳米棒,体外近红外照射后,隐球菌活性较未偶联抗体的金纳米棒组显著降低。结论靶向性金纳米棒显著增强了近红外激光对隐球菌的光热效应,可用于治疗隐球菌感染的新尝试。     

Recent advances in the antilung cancer activity of biosynthesized gold nanoparticles

Gold nanoparticles (Au-NPs) have been widely used in biomedical fields such as imaging, diagnosis, and treatment because of their special characteristics. Au-NPs can be synthesized using several methods, including the biological method, also called green or eco-friendly synthesis. Recent studies have reported the anticancer activity of biosynthesized Au-NPs, especially in lung cancer. This review focused on the advances in the antilung cancer activity of biosynthesized Au-NPs and its potential mechanisms.     

Estimation of tumor and local tissue dose in gold nanoparticles radiotherapy for prostate cancer

AimThe objective of this research was to estimate the dose distribution delivered by radioactive gold nanoparticles (¹⁹⁸AuNPs or ¹⁹⁹AuNPs) to the tumor inside the human prostate as well as to normal tissues surrounding the tumor using the Monte-Carlo N-Particle code (MCNP-6.1.1 code).BackgroundRadioactive gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated to treat prostate cancer in animals. In order to use them as a new therapeutic modality to treat human prostate cancer, accurate radiation dosimetry simulations are required to estimate the energy deposition in the tumor and surrounding tissue and to establish the course of therapy for the patient.Materials and methodsA simple geometrical model of a human prostate was used, and the dose deposited by ¹⁹⁸AuNPs or ¹⁹⁹AuNPs to the tumor within the prostate as well as to the healthy tissue surrounding the prostate was calculated using the MCNP code. Water and A-150 TEP phantoms were used to simulate the soft and tumor tissues.ResultsThe results showed that the dose due to ¹⁹⁸AuNPs or ¹⁹⁹AuNPs, which are distributed homogenously in the tumor, had a maximal value in the tumor region and then rapidly decreased toward the prostate–tumor interface and surrounding organs. However, the dose deposited by ¹⁹⁸Au is significantly higher than the dose deposited by ¹⁹⁹Au in the tumor region as well as normal tissues.ConclusionsAccording to the MCNP results, ¹⁹⁸AuNPs are a promising modality to treat prostate cancer and other cancers and ¹⁹⁹AuNPs could be used for imaging purposes.