Neoplastic cell response to tiopronin-coated gold nanoparticles

The present study characterized the in vitro biological response of a comprehensive set of cancer cell lines to gold nanoparticles (2.7 nm) coated with tiopronin (AuNPs-TP). Our findings suggest that upon entering cells, the AuNPs-TP are sequestered in vacuoles such as endosomes and lysosomes, and mostly localize in perinuclear areas. Peak cell accumulation was achieved at 8 hours after incubation. L929 and H520 cells showed more than 75% surviving fraction when treated with 0.5 mg/mL of AuNPs-TP for 24 hours, whereas the surviving fractions were 60% in MCF-7 and 20% in HeLa cells. Reactive oxygen species (ROS) production by the AuNPs-TP was dependent on cell line and exposure time. Antioxidants inhibited ROS generation to various extents, with glutathione and tiopronin being most effective. Overall, exposure time, concentration of the AuNPs-TP, and cell line influenced neoplastic cell response. Furthermore, the mechanism of cytotoxicity of the AuNPs-TP was found to be ROS generation.From the Clinical EditorThis study describes the basic intracellular characteristics of Tiopronin-Au nanoparticles from the standpoint of their anti-cancer activity in different cancer cell cultures.     

Multistability in platelets and their response to gold nanoparticles

The nanoparticle (NP) response of platelets is shown to be critically dependent on extent of preactivation of platelets by an agonist like ADP. A transition from de-aggregatory to aggregatory state is triggered in the presence of gold NPs (AuNP) only in such critical conditions. Adhered and suspended platelets respond differentially to NPs. Preactivation in the adhered state induced by shear force explains such observation. The NP effect is associated with enhanced release reaction, tyrosine phosphorylation and CD62P expression level. Unlike cancer cells, whose response is maximal when NP size is optimal (within the range 50 - 70 nm), the platelet response monotonically increases with reduction of the AuNP size. The uptake study, using quenching of quinacrine hydrochloride fluorescence by AuNP, indicates that accumulation 18 nm AuNP is several-fold higher than the 68 nm AuNP. It is further shown that AuNP response can provide a simple measure for thrombotic risk associated with nano-drugs. FROM THE CLINICAL EDITOR: Platelet aggregation can be triggered in the presence of gold nanoparticles (AuNP). Platelet response monotonically increases with reduction of the AuNP size. AuNP response can provide a simple measure for thrombotic risk associated with nano-drugs.     

Radiotherapy enhancement with gold nanoparticles

Gold is an excellent absorber of X-rays. If tumours could be loaded with gold, this would lead to a higher dose to the cancerous tissue compared with the dose received by normal tissue during a radiotherapy treatment. Calculations indicate that this dose enhancement can be significant, even 200% or greater. In this paper, the physical and biological parameters affecting this enhancement are discussed. Gold nanoparticles have shown therapeutic efficacy in animal trials and these results are reviewed. Some 86% long-term (>1 year) cures of EMT-6 mouse mammary subcutaneous tumours was achieved with an intravenous injection of gold nanoparticles before irradiation with 250-kVp photons, whereas only 20% were cured with radiation alone. The clinical potential of this approach is also discussed.     

Anti-glycation activity of gold nanoparticles

Anti-glycation activity of gold nanoparticles (GNPs) has been reported for the first time. Nonenzymatic glycation of alpha-crystallin leads to formation of cataract, or opaque aggregate of proteins. In this article we report prevention of glycation of alpha-crystallin by conjugation with GNPs. Formation of advanced glycosylic end products is prevented even if a strong glycating agent such as fructose is used. In addition, the nanoconjugation can provide some important information on the structural distribution of this dynamic chaperone protein. Because GNPs are biocompatible, their reported anti-glycation activity may have ophthalmological implications.     

载药金纳米粒的研究进展

近年来,作为一种新型药物递送系统,金纳米粒已引起了广泛关注。由于其特殊的物理化学性质,能与多种类型药物发生相互作用,如蛋白质、核酸、小分子药物等,从而可应用于肿瘤治疗和检测。笔者对载药金纳米粒的制备方法、载药方式和安全性等问题进行综述。     

Direct visualization of protein adsorption to primary containers by gold nanoparticles

Adsorption of proteins to primary containers can result in protein loss, protein denaturation, or aggregation. We report a simple and effective method to directly detect and visualize adsorption of proteins to container surfaces by staining adsorbed proteins with gold nanoparticles, which bind proteins nonspecifically. The gold nanoparticle staining method was applied to study adsorption to siliconized glass prefilled syringes (PFSs) of a therapeutic protein in a liquid formulation. The protein was found to preferentially adsorb to glass surfaces over siliconized surfaces in PFSs. The presence of adsorbed proteins on glass surfaces was confirmed by in situ Raman spectroscopy. Gold nanoparticle staining patterns revealed that adsorption of proteins to hydrophobic cyclic olefin polymer plastic vials was minimized compared with hydrophilic type I glass vials. Bovine serum albumin (BSA) also preferentially adsorbed to glass surfaces compared with siliconized surfaces as revealed by the gold staining patterns in PFS incubated with BSA, supporting the use of albumin to minimize loss of proteins in glass containers. The method is particularly valuable for high-concentration protein formulations in which adsorption of proteins to containers cannot be easily detected by other methods.     

载阿霉素金纳米粒的制备和细胞毒性研究

目的 构建载阿霉素（DOX）的甲氧基聚乙二醇（mPEG）修饰的金纳米粒AuNPs-mPEG@DOX，以降低DOX的毒副作用。方法 制备AuNPs-mPEG@DOX，通过粒径、电位和紫外可见光吸收光谱（UV-Vis）进行表征。考察连接巯基的DOX（HS-DOX）投药浓度对AuNPs-mPEG@DOX吸附率和载药量的影响。建立未吸附HS-DOX含量测定的高效液相色谱法（HPLC），对专属性、线性、精密度、稳定性和加样回收率进行考察。采用CCK-8法检测AuNPs-mPEG@DOX对MCF-10A和MCF-7细胞的毒性作用。结果 成功制备了AuNPs-mPEG@DOX，粒径为（46.12±0.49） nm，电位为（18.60±1.51） mV，最大吸收波长为530 nm。建立了可用于检测AuNPs-mPEG@DOX未吸附HS-DOX含量的HPLC方法，测定最佳投药浓度11.18 μg/ml，HS-DOX条件下的吸附率为（9.21±2.88）%，载药量为（2.01±0.62）%。细胞毒性实验表明AuNPs-mPEG@DOX可明显降低DOX对正常乳腺细胞的毒副作用；DOX在≥4.75 μmol/L时，AuNPs-mPEG@DOX与游离DOX对乳腺肿瘤细胞的细胞毒性作用一致。结论 AuNPs-mPEG@DOX可有效降低DOX的毒副作用，为后续AuNPs连接药物降低其毒副作用的研究提供参考。     

Monolayer coated gold nanoparticles for delivery applications

Gold nanoparticles (AuNPs) provide attractive vehicles for delivery of drugs, genetic materials, proteins, and small molecules. AuNPs feature low core toxicity coupled with the ability to parametrically control particle size and surface properties. In this review, we focus on engineering of the AuNP surface monolayer, highlighting recent advances in tuning monolayer structures for efficient delivery of drugs and biomolecules. This review covers two broad categories of particle functionalization, organic monolayers and biomolecule coatings, and discusses their applications in drug, DNA/RNA, protein and small molecule delivery.     

Anti-glycation effect of gold nanoparticles on collagen

Gold nanoparticles (GNPs) have been reported to exhibit a variety of biological effects including anti-inflammatory and anti-oxidant activities. The extent of an in vitro glycation reaction mixture of collagen and glycolaldehyde was assayed to investigate the inhibition of glycolaldehye-derived advanced glycation end products (glycol-AGEs) formation with GNPs in collagen, which is a major protein component of the human dermis. GNP-treated collagen showed significantly less glycation (56.3 ± 4.2%) than an untreated glycation control. Moreover, GNP-treated glycation in a collagen lattice model significantly decreased the AGEs distribution in the model system. Taken together, these results suggest that GNPs have the potential for use in the prevention of glycation-induced skin aging.     

Size-dependent tissue kinetics of PEG-coated gold nanoparticles

Gold nanoparticles (AuNPs) can be used in various biomedical applications, however, very little is known about their size-dependent in vivo kinetics. Here, we performed a kinetic study in mice with different sizes of PEG-coated AuNPs. Small AuNPs (4 or 13 nm) showed high levels in blood for 24 h and were cleared by 7 days, whereas large (100 nm) AuNPs were completely cleared by 24 h. All AuNPs in blood re-increased at 3 months, which correlated with organ levels. Levels of small AuNPs were peaked at 7 days in the liver and spleen and at 1 month in the mesenteric lymph node, and remained high until 6 months, with slow elimination. In contrast, large AuNPs were taken up rapidly (∼ 30 min) into the liver, spleen, and mesenteric lymph nodes with less elimination phase. TEM showed that AuNPs were entrapped in cytoplasmic vesicles and lysosomes of Kupffer cells and macrophages of spleen and mesenteric lymph node. Small AuNPs transiently activated CYP1A1 and 2B, phase I metabolic enzymes, in liver tissues from 24 h to 7 days, which mirrored with elevated gold levels in the liver. Large AuNPs did not affect the metabolic enzymes. Thus, propensity to accumulate in the reticuloendothelial organs and activation of phase I metabolic enzymes, suggest that extensive further studies are needed for practical in vivo applications.     

Photoactivation of gold nanoparticles for glioma treatment

Radiosensitization efficacy of gold nanoparticles (AuNPs) with low energy radiations (88 keV) was evaluated in vitro and in vivo on rats bearing glioma. In vitro, a significant dose-enhancement factor was measured by clonogenic assays after irradiation with synchrotron radiation of F98 glioma cells in presence of AuNPs (1.9 and 15 nm in diameter). In vivo, 1.9 nm nanoparticles were found to be toxic following intracerebral delivery in rats bearing glioma, whether no toxicity was observed using 15 nm nanoparticles at the same concentration (50 mg/mL). The therapeutic efficacy of gold photoactivation was determined by irradiating the animals after intracerebral infusion of AuNPs. Survival of rats that had received the combination of treatments (AuNPs: 50 mg/mL, 15 Gy) was significantly increased in comparison with the survival of rats that had received irradiation alone. In conclusion, this experimental approach is promising and further studies are foreseen for improving its therapeutic efficacy.From the Clinical EditorThese investigators report that gold nanoparticles of the correct size can be used to enhance the effects of irradiation in the context of a glioma model. Since many of the glioma varieties are currently incurable, this or similar approaches may find their way to clinical trials in the near future.     

Disaggregation of gold nanoparticles by Daphnia magna

Abstract

The use of manufactured nanomaterials is rapidly increasing, while our understanding of the consequences of releasing these materials into the environment is still limited and many questions remain, for example, how do nanoparticles affect living organisms in the wild? How do organisms adapt and protect themselves from exposure to foreign materials? How does the environment affect the performance of nanoparticles, including their surface properties? In an effort to address these crucial questions, our main aim has been to probe the effects of aquatic organisms on nanoparticle aggregation. We have, therefore, carried out a systematic study with the purpose to disentangle the effects of the freshwater zooplankter, Daphnia magna, on the surface properties, stability, and aggregation properties of gold (Au) nanoparticles under different aqueous conditions as well as identified the proteins bound to the nanoparticle surface. We show that Au nanoparticles aggregate in pure tap water, but to a lesser extent in water that either contains Daphnia or has been pre-conditioned with Daphnia. Moreover, we show that proteins generated by Daphnia bind to the Au nanoparticles and create a modified surface that renders them less prone to aggregation. We conclude that the surrounding milieu, as well as the surface properties of the original Au particles, are important factors in determining how the nanoparticles are affected by biological metabolism. In a broader context, our results show how nanoparticles released into a natural ecosystem become chemically and physically altered through the dynamic interactions between particles and organisms, either through biological metabolism or through the interactions with biomolecules excreted by organisms into the environment.     

Nuclear penetration of surface functionalized gold nanoparticles

Free gold nanoparticles easily aggregate when the environment conditions change. Here, gold nanoparticles (AuNPs) with average diameter of 3.7 nm were prepared and then modified with poly(ethylene glycol) (PEG) to improve stability. The gold nanoparticles were first surface-modified with 3-mercaptopropionic acid (MPA) to form a self-assembled monolayer and subsequently conjugated with NH₂-PEG-NH₂ through amidation between the amine end groups on PEG and the carboxylic acid groups on the particles. The biocompatibility and intracellular fate of PEG-modified gold nanoparticles (AuNP@MPA-PEG) were then studied in human cervical cancer (HeLa) cells. Cell viability test showed that AuNP@MPA-PEG did not induce obvious cytotoxicity. Both confocal laser scanning microscopy and transmission electron microscopy demonstrated that AuNP@MPA-PEG entered into mammalian cells and the cellular uptake of AuNP@MPA-PEG was time-dependent. Inductively coupled plasma mass spectrometry and confocal microscopy imaging further demonstrated that AuNP@MPA-PEG penetrated into the nucleus of mammalian cells upon exposure for 24 h. These results suggest that surface modification can enhance the stability and improve the biocompatibility. This study also indicates that AuNP@MPA-PEG can be used as potential nuclear targeted drug delivery carrier.     

Labeling and tracking cells with gold nanoparticles

Gold nanoparticles (AuNPs) have garnered much attention as contrast agents for computerized tomography (CT) because of their facile synthesis and surface functionalization, in addition to their significant X-ray attenuation and minimal cytotoxicity. Cell labeling using AuNPs and tracking of the labeled cells using CT has become a time-efficient and cost-effective method. Actively targeted AuNPs can enhance CT contrast and sensitivity, and further reduce the radiation dosage needed during CT imaging. In this review, we summarize the state-of-the-art use of AuNPs in CT for cell tracking, including the precautionary steps necessary for their use and the difficulty in translating the process into clinical use.     

包含金纳米粒子的聚电解质微囊的制备

本文制备了含金纳米粒子的聚电解质微囊, 并进行了表征。以碳酸钙粒子为模板, 在其表面组装聚烯丙基胺盐酸盐 [poly (allyamine hydrochloride), PAH] 和金纳米粒子, 得到以碳酸钙粒子为母核, PAH/金纳米粒子为壳的核壳结构微粒。用乙二胺四乙酸二钠 (EDTA) 溶解碳酸钙, 即可得到含有金纳米粒子的聚电解质微囊。用扫描电镜表征碳酸钙粒子、含金纳米粒子的聚电解质微囊去掉母核前后的形状, 可观察到碳酸钙粒子表面包裹金纳米粒子前后的差别。用显微镜表征了微囊在溶液中的形态, 微囊在水中分散性良好。载入异硫氰酸荧光素标记的牛血清白蛋白 (FITC-bovine serum albumin, FITC-BSA) 作为模型药物, 用荧光显微镜可以观察到微囊内有一定的荧光强度, 检测得到牛血清白蛋白的包封率为 (34.31 ± 2.44) %, 聚电解质微囊载药量为 (43.75 ± 3.12) mg·g⁻¹。     

Review on gold nanoparticles and their applications

Gold nanoparticles are widely used in many fields as preferred materials for their unique optical and physical properties, such as surface plasmon oscillations for labeling, imaging, and sensing. Recently, many advancements were made in biomedical applications with better biocompatibility in disease diagnosis and therapeutics. Au-NPs could be prepared and conjugated with many functionalizing agents, such as polymers, surfactants, ligands, dendrimers, drugs, DNA, RNA, proteins, peptides and oligonucleotides. This review addressed the use of gold nanoparticles and the surface functionalization with a wide range of molecules, expanding and improving gold nanoparticles in targeting drugs for photothermal therapy with reduced cytotoxic effcts in various cancers, gene therapy and many other diseases. Overall, Au-NPs would be a promising vehicle for drug delivery and therapies.     

An aptasensor for selective,sensitive and fast detection of lead(II) based on polyethyleneimine and gold nanoparticles

Lead (Pb), as a major environmental contaminant, could be harmful to humans when inhaled or ingested. In this study, we developed a sensitive, selective and fast colorimetric aptasensor for Pb⁺² based on polyethylenimine (PEI) and gold nanoparticles (AuNPs). In the absence of Pb⁺², aptamer binds to PEI. So the well-dispersed AuNPs remain stable with a wine-red color. Upon the addition of Pb⁺², a conformational change happens and a G-quadruplex aptamer/Pb⁺² complex is formed, leading to the aggregation of AuNPs and a color change to blue. This sensor showed a high selectivity toward Pb⁺² with a limit of detection (LOD) as low as 702 pM. Moreover, our fabricated sensor was successfully applied for Pb⁺² detection in rat serum and tap water.     

Cellular transport pathways of polymer coated gold nanoparticles

The different transport pathways of 5-nm polymer-coated gold nanoparticles (Au NPs) crossing epithelial Caco-2 cell monolayers were explored. We found that the majority of cationic and neutral Au NPs depended heavily on endocytosis for cellular uptake and transport, and the anionic charged nanoparticles trafficked preferentially through the tight junctions (i.e., a paracellular pathway). The current study demonstrates that the surface chemistry of neutral polymer coatings dictate the trafficking through Caco-2 cell monolayers; poly(ethylene glycol)-coated Au NPs traffic via an endocytosis pathway assisted by microtubules; poly(2,3-hydroxy-propylacrylamide)-coated Au NPs traffic via endocytosis but assisted by other nonmicrotubular pathways. The Au NPs coated with poly(N-isopropylacrylamide) (hydrophobic above the lower critical solution temperature of 32°C) traffic via either the microtubule-assisted endocytosis pathway or the paracellular pathway depending on the temperature. This knowledge will aid in the future of the design of nanoparticles as potential oral drug carriers. FROM THE CLINICAL EDITOR: The authors examined different transport pathways of polymer-coated gold nanoparticles to cross epithelial Caco-2 cells, concluding that surface chemistry of neutral polymer coatings dictates the trafficking through monolayers.     

Cancer cell response to nanoparticles: criticality and optimality

A stochastic variation in size and electrical parameters is common in nanoparticles. Synthesizing gold nanoparticles with a varying range of size and zeta potential, we show that there is clustering at certain regions of hydrodynamic diameter and zeta potentials that can be classified using k-clustering technique. A cluster boundary was observed around 50 nm, a size known for its optimal response to cells. However, neither size nor zeta potential alone determined the optimal cellular response (e.g., percentage cell survival) induced by such nanoparticles. A complex interplay prevails between size, zeta potential, nature of surface functionalization, and extent of adhesion of the cell to a solid matrix. However, it follows that the ratio of zeta potential to surface area, which scales as the electrical field (by Gaussian law), serves as an appropriate indicator for optimal cellular response. The phase plot spanned by fractional survival and effective electric field (charge density) indicates a positive correlation between mean cell survival and the magnitude of the electric field. The phase plot spanned by fractional survival and effective electric field (charge density) associated with the nanosurface shows a bifurcation behavior. Wide variation of cell survival response is observed at certain critical values of the surface charge density, whereas in other ranges the cellular response is well behaved and more predictable. Existence of phase points near the critical region corresponds to wide fluctuation of nanoparticle-induced response, for small changes in the nanosurface property. Smaller nanoparticles with low zeta potential (e.g., those conjugated with arginine) can have such an attribute (i.e., higher electrical field strength), and eventually they cause more cell death. The study may help in optimal design of nanodrugs.     

Protracted elimination of gold nanoparticles from mouse liver

The present study aims at revealing the fate of 40-nm gold nanoparticles after intravenous injections. The gold nanoparticles were traced histochemically with light and transmission electron microscopy using autometallographic (AMG) staining, and the gold content in the liver was determined with inductively coupled plasma mass spectrometry (ICP-MS). Gold nanoparticles were identified in almost all Kupffer cells one day after the injection, but the fraction of gold-loaded cells gradually decreased to about one fifth after 6 months. Transmission electron microscopic analysis showed that the gold nanoparticles had accumulated inside the vesicular lysosome/endosome-like structures of the macrophages. At day 1, about 4.5‰ of the area of the liver sections was AMG-stained, after 1 month it had decreased to 0.7‰, and thereafter no further significant reduction was recorded. Because ICP-MS only showed a 9% fall in the gold content over the observed 6 months, the AMG finding of a significant reduction in the stained area of the liver sections and number of macrophages loaded with gold nanoparticles reveals that over time an increasing part of the total amount of gold nanoparticles in the liver is contained in fewer macrophages accumulated in growing clusters.