Zebrafish as a correlative and predictive model for assessing biomaterial nanotoxicity

The lack of correlative and predictive models to assess acute and chronic toxicities limits the rapid pre-clinical development of new therapeutics. This barrier is due in part to the exponential growth of nanotechnology and nanotherapeutics, coupled with the lack of rigorous and robust screening assays and putative standards. It is a fairly simple and cost-effective process to initially screen the toxicity of a nanomaterial by using invitro cell cultures; unfortunately it is nearly impossible to imitate a complimentary invivo system. Small mammalian models are the most common method used to assess possible toxicities and biodistribution of nanomaterials in humans. Alternatively, Daniorerio, commonly known as zebrafish, are proving to be a quick, cheap, and facile model to conservatively assess toxicity of nanomaterials.     

Antibiofilm activity of nanosized magnesium fluoride

The ability of bacteria to develop antibiotic resistance and colonize abiotic surfaces by forming biofilms is a major cause of medical implant-associated infections and results in prolonged hospitalization periods and patient mortality. This raises the urgent need to develop compounds that can inhibit bacterial colonization of surfaces. In this study, we present an unreported microwave-based synthesis of MgF₂ nanoparticles (Nps) using ionic liquid. We demonstrate the antimicrobial activity of these fluoride nanomaterials and their ability to restrict biofilm formation of common bacterial pathogens. Scanning and transmission electron microscopic techniques indicated that the MgF₂·Nps attach and penetrate into the cells. Flow cytometry analysis revealed that the Nps caused a disruption in the membrane potential. The MgF₂·Nps also induced membrane lipid peroxidation and once internalized can interact with chromosomal DNA. Based on these findings we further explored the possibility of using the MgF₂·Nps to coat surfaces and inhibit biofilm formation. A microwave synthesis and coating procedure was utilized to coat glass coupons. The MgF₂ coated surfaces effectively restricted biofilm formation of the tested bacteria. Taken together these results highlight the potential for developing MgF₂ nanoparticles in order to inhibit bacterial infections.     

智能纳米材料在细胞水平治疗疾病时的应用

摘要：恶性肿瘤的常规治疗方法在临床应用中存在着或多或少的缺陷。为了实现靶向治疗及提高药物利用度等目的,一类具有智能效应(如热敏感、pH敏感、磁敏感以及光敏感等)的纳米材料已被应用到细胞水平治疗疾病的领域中。它们是通过药物靶向缓释、热效应和可控机械力等方式,杀死靶组织内的病理细胞,进而实现疾病的治愈。文章综合讨论了应用该类材料在细胞水平治疗疾病的最新进展,同时展望了其存在的问题以及发展前景。     

纳米羟基磷灰石颗粒诱导对大鼠巨噬细胞凋亡影响的初步研究

由于其尺寸效应,纳米颗粒（NPs）可以结合细胞内大分子,从而引起细胞坏死或凋亡。而目前针对纳米颗粒的生物安全性,缺乏对颗粒致细胞凋亡的机理研究。目的：从细胞及分子水平上探讨纳米颗粒致细胞凋亡的机理,为纳米颗粒的安全应用提供科学依据。设计、时间及地点：2007年1月至2008年12月,在上海生物材料研究测试中心完成以下相关实验。材料：原代培养大鼠巨噬细胞,并在300W/40KHZ的超声条件下制备纳米羟基磷灰石颗粒（HAP NPs）的悬浮液（30-80nm）。方法：为探讨纳米陶瓷颗粒对细胞的损伤作用及凋亡机制,本研究应用透射电镜（TEM）观察细胞凋亡的超微结构表征;AnnexinV-EGFP/PI双染检测凋亡结果;Western Blot方法检测凋亡调控相关基因P53的表达变化。主要观察指标：凋亡率及P53的蛋白表达水平。结果：TEM 观察单核巨噬细胞经HAP NPs作用后具有典型的凋亡形态学特征;并且细胞的凋亡与NPs的浓度呈正相关;Western Blot结果显示,100 µg/ml HAP NPs引起P53表达显著上调。 结论：本研究结果提示HAP NPs颗粒能够通过蛋白磷酸化上调P53蛋白,从而能够启动下游相关基因,最终导致细胞凋亡。同时也可以认为,P53是用来进行纳米陶瓷颗粒安全性评价较为理想的指标。     

Nanoparticles: Emerging carriers for drug delivery

The core objective of nanoparticles is to control and manipulate biomacromolecular constructs and supramolecular assemblies that are critical to living cells in order to improve the quality of human health. By definition, these constructs and assemblies are nanoscale and include entities such as drugs, proteins, DNA/RNA, viruses, cellular lipid bilayers, cellular receptor sites and antibody variable regions critical for immunology and are involved in events of nanoscale proportions. The emergence of such nanotherapeutics/diagnostics will allow a deeper understanding of human longevity and human ills that include cancer, cardiovascular disease and genetic disorders. A technology platform that provides a wide range of synthetic nanostructures that may be controlled as a function of size, shape and surface chemistry and scale to these nanotechnical dimensions will be a critical first step in developing appropriate tools and a scientific basis for understanding nanoparticles.     

TMC–MCC (N-trimethyl chitosan–mono-N-carboxymethyl chitosan) nanocomplexes for mucosal delivery of vaccines

In this study, for the first time, TMC/MCC complex nanoparticles as a delivery system and as an adjuvant were developed and evaluated to obtain systemic and mucosal immune responses against nasally administered tetanus toxoid (TT). Nanoparticles were developed by complexation between the oppositely charged chitosan derivatives, N-trimethyl chitosan (TMC, polycationic) and mono-N-carboxymethyl chitosan (MCC, polyampholytic) without using any crosslinker for mucosal vaccination. The cellular viability was found to be higher with TMC/MCC complex compared to that of MCC and TMC alone. Size, zeta potential and morphology of the nanoparticles were investigated as a function of preparation method. Nanoparticles with high loading efficacy (95%) and positively charged surface were obtained with an average particle size of 283 ± 2.5 nm. The structural integrity of the TT in the nanoparticles was confirmed by SDS–PAGE electrophoresis analysis. Cellular uptake studies indicated that FITC-BSA loaded nanoparticles were effectively taken up into the mouse Balb/c monocyte macrophages. Mice were nasally immunized with TT loaded TMC/MCC complex nanoparticles and compared to that of TMC and MCC nanoparticles. TMC/MCC complex nanoparticles were shown to induce both the mucosal and systemic immune response indicating that this newly developed system has potential for mucosal administration of vaccines.     

Design and influence of γ-irradiation on the biopharmaceutical properties of nanoparticles containing an antigenic complex from Brucella ovis

Despite vaccination campaigns, brucellosis is still one of the most common bacterial zoonosis in the world. This work describes the development of a novel formulation strategy to the delivery of the Brucella ovis antigenic extract (HS) into ovine mucosal surfaces. Thus, HS was entrapped in conventional and mannosylated poly(anhydride) nanoparticles by the solvent displacement method, and the resulting nanosystems were γ-irradiated to accomplish the sterilization required for the ophthalmic administration route. Sterilization, at either 10 kGy or 25 kGy, did not modify the size, morphology and antigen content of the nanoparticles. Similarly, the integrity and antigenicity of the entrapped antigen were not affected by γ-irradiation. The 25 kGy γ-irradiation dose seemed to influence negatively the HS release from the carriers. However, and in accordance with the Pearson's correlation, all the release patterns followed a similar tendency. Furthermore, the stability of the vaccine systems on lachrymal and nasal ovine fluids, showed that γ-irradiation had no significant effects on the vaccine systems. Since all the vaccine systems accomplished the pharmacopoeial biological tests required for γ-irradiation doses under 25 kGy, these results are highly suggestive for the use of HS loaded poly(anhydride) nanoparticles as an efficient vaccine delivery system for brucellosis immunoprophylaxis, especially for ophthalmic administration.     

Retrospective analysis of 4-week inhalation studies in rats with focus on fate and pulmonary toxicity of two nanosized aluminum oxyhydroxides (boehmite) and pigment-grade iron oxide (magnetite): The key metric of dose is particle mass and not particle surface area

This paper compares the pulmonary toxicokinetics and toxicodynamics of three different types of poorly soluble dusts examined in repeated rat inhalation bioassays (6 h/day, 5 days/week, 4 weeks). In these studies the fate of particles was studied during a 3–6-month postexposure period. This retrospective analysis included two types of aluminum oxyhydroxides (AlOOH, boehmite), high purity calcined, and agglomerated nanosized aluminas of very low solubility with primary isometric particles of 10 or 40 nm, and synthetic iron oxide black (Fe₃O₄ pigment grade). Three metrics of dose (actual mass concentration, surface area concentration, mass-based lung burden) were compared with pulmonary toxicity characterized by bronchoalveolar lavage. The results of this analysis provide strong evidence that pulmonary toxicity (inflammation) corresponds best with the mass-based cumulative lung exposure dose. The inhalation study with a MMAD of ≈0.5 μm yielded a higher pulmonary dose than MMADs in the range of 1–2 μm, a range most commonly used in repeated exposure inhalation studies. Hence, a key premise for the dosimetric adjustment across species is that comparable lung tissue doses should cause comparable effects. From that perspective, the determination of mass-based pulmonary lung burdens appears to be amongst the most important and critical nominator of dose and dose-related pulmonary toxicity.     

PVP-coated silver nanoparticles and silver ions induce reactive oxygen species, apoptosis and necrosis in THP-1 monocytes

The objective of the present study was to investigate the toxicity of silver nanoparticles (Ag NPs) in vitro. Silver ions (Ag+) have been used in medical treatments for decades whereas Ag NPs have been used in a variety of consumer products within recent years. This study was undertaken to compare the effect of well characterized, PVP-coated Ag NPs (69 nm ± 3 nm) and Ag+ in a human monocytic cell line (THP-1). Characterization of the Ag NPs was conducted in both stock suspension and cell media with or without serum and antibiotics. By using the flowcytometric annexin V/propidium iodide (PI) assay, both Ag NPs and Ag+ were shown to induce apoptosis and necrosis in THP-1 cells depending on dose and exposure time. Furthermore, the presence of apoptosis could be confirmed by the TUNEL method. A number of studies have implicated the production of reactive oxygen species (ROS) in cytotoxicity mediated by NPs. We used the fluorogenic probe, 2′,7′-dichlorofluorescein to assess the levels of intracellular ROS during exposure to Ag NPs and Ag+. A drastic increase in ROS levels could be detected after 6–24 h suggesting that oxidative stress is an important mediator of cytotoxicity caused by Ag NPs and Ag+.