Jiao Sun

Biodistribution and toxicity of intravenously administered silica nanoparticles in mice

As the biosafety of nanotechnology becomes a growing concern, the in vivo nanotoxicity of NPs has drawn a lot of attention. Silica nanoparticles (SiNPs) have been widely developed for biomedical use, but their biodistribution and toxicology have not been investigated extensively in vivo. Although investigations of in vivo qualitative distribution of SiNPs have been reported, the time-dependent and quantitative informations about the distribution of SiNPs are still lacking. Here we investigated the long-term (30xa0days) quantitative tissue distribution, and subcellular distribution, as well as potential toxicity of two sizes of intravenously administered SiNPs in mice using radiolabeling, radioactive counting, transmission electron microscopy and histological analysis. The results indicated that SiNPs accumulate mainly in lungs, liver and spleen and are retained for over 30xa0days in the tissues because of the endocytosis by macrophages, and could potentially cause liver injury when intravenously injected.

Effects of four types of hydroxyapatite nanoparticles with different nanocrystal morphologies and sizes on apoptosis in rat osteoblasts

Hydroxyapatite nanoparticles (nano‐HAP) have been reported to cause inflammatory reactions. Here, we aimed to compare the effects of four types of nano‐HAP with different nanocrystal morphologies (short rod‐like, long rod‐like, spherical or needle‐shaped crystals) and sizes (10–20, 10–30 or 20–40u2009nm) on growth inhibition and apoptosis in primary cultured rat osteoblasts. The osteoblasts was treated with the four types of nano‐HAP at various concentrations (20, 40, 60, 80 or 100u2009mgu2009l−1). The nano‐HAP specific surface area was detected using the Brunauer, Emmet and Teller method. The cell growth rate was detected using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay; apoptotic alterations and the level of reactive oxygen species in osteoblasts were measured using flow cytometry; and the amounts of apoptotic p53 and cytochrome c proteins were measured using western blotting. We observed that all four types of nano‐HAP inhibited the growth of osteoblasts in a dose‐dependent manner. These nano‐HAP significantly induced apoptosis in osteoblasts. Nano‐HAP with smaller specific surface areas induced lower apoptosis rates. The needle‐shaped and the short rod‐like particles induced greater cellular injury than the spherical and long rod‐like particles, respectively. The increased apoptosis rates were accompanied by increased p53 and cytochrome c expression. These findings indicate that nano‐HAP inhibit the activity of osteoblasts and also induce the apoptosis of osteoblasts in vitro. These findings also suggest that the nano‐HAP‐induced apoptotic pathway is mediated by a mitochondrial‐dependent pathway. Moreover, the sizes, morphologies and concentrations of nano‐HAP have significant effects on the apoptotic level. Copyright

Tissue distribution and excretion of intravenously administered titanium dioxide nanoparticles.

As the biosafety of nanotechnology becomes a growing concern, the in vivo nanotoxicity of nanoparticles (NPs) has been drawn an increasing attention. Titanium dioxide nanoparticles (TiO(2)-NPs) have been developed for versatile use, but the pharmacokinetics of intravenously administered TiO(2)-NPs have not been investigated extensively. In the present study, the rutile-type TiO(2)-NPs with a size about 20nm were labeled with CF680 and (125)I. The labeled TiO(2)-NPs were injected in mice or rats with the concentration of 1mg/ml and the dose of 10mg/kg body weight and their tissue distribution and excretion were investigated by using ex vivo fluorescent imaging, γ-counter and TEM. The results indicated that the TiO(2)-NPs mainly accumulated in liver and spleen and could be retained for over 30days in these tissues due to the phagocytosis by macrophages. The excretion assay found that the excretory rate of TiO(2)-NPs through urine was higher than that of feces, indicating that renal excretion was the main excretion pathway of TiO(2)-NPs. Overall results of the present study provided important information on distribution and excretion of TiO(2)-NPs in vivo, which would greatly promote the pharmacokinetics and in vivo nanotoxicity research of TiO(2)-NPs.

Hydroxyapatite nanoparticles as a controlled-release carrier of BMP-2: absorption and release kinetics in vitro

Recently, nanoparticles have been extensively developed as controlled-release carriers; however, there has been little research on hydroxyapatite nanoparticles (HANPs) and their potential applications. In this study, HANPs were investigated as a controlled-release carrier of bone morphogenetic protein-2 (BMP-2), the absorption and release kinetics of which were analyzed in vitro. Different concentrations of BMP-2 solution were used to evaluate the adsorptive properties of HANPs. It was observed that the amount of BMP-2 adsorbed onto HANPs could be as high as 70xa0μg/mg and that adsorption rate was highly correlated with the concentration of BMP-2 solution used. After absorption, the suspension of HANPs absorbed BMP-2 (HANPs/BMP-2) was incubated at 37°C for 15xa0days and the release kinetics of BMP-2 from HANPs/BMP-2 was determined daily. The release profile showed sustained release of BMP-2 over the period of the investigation. Collectively, these results suggest that HANPs has the potential to function as a carrier for drug delivery systems and as a scaffold material in bone tissue engineering.

Study on MCP-1 related to inflammation induced by biomaterials

The study of inflammation is important for understanding the reaction between biomaterials and the human body, in particular, the interaction between biomaterials and immune system. In the current study, rat macrophages were induced by multiple biomaterials with different biocompatibilities, including polyvinyl chloride (PVC) containing 8% of organic tin, a positive control material with cellular toxicity. Human umbilical vein endothelial cells (ECV-304), cultured with PRMI-1640, were detached from cells cultured with the supernatant of macrophages containing TNF-alpha and IL-1beta because of stimulation by biomaterials. The cells were then treated with different biomaterials. Then both TNF-alpha and IL-1beta in macrophages were detected by ELISA. Levels of monocyte chemoattractant protein-1 (MCP-1) were measured by RT-PCR. The results suggested that the expression of TNF-alpha and IL-1beta was elevated by polytetrafluoroethylene (PTFE), polylactic-co-glycolic acid (PLGA) and American NPG alloy (p < 0.001). The level of MCP-1 cultured in supernatant of macrophages was higher than in PRMI-1640 with the same biomaterials. And the exposure to PTFE, PLGA and NPG resulted in the high expression of MCP-1 (p < 0.001) following cytokine stimulation. MCP-1 was also significantly expressed in beta-tricalcium phosphate (beta-TCP) and calcium phosphate cement samples (CPC) (p < 0.01). Thus, TNF-alpha, IL-1beta and MCP-1 had played an important role in the immune reaction induced by biomaterials and there was a close relationship between the expression of cytokines and biomcompatibility of biomaterials. Furthermore, these data suggested that MCP-1 was regulated by TNF-alpha and IL-1beta, and activated by both cytokines and biomaterials. The data further suggested that the expression of MCP-1 could be used as a marker to indicate the degree of immune reaction induced by biomaterials.

Body distribution of poly(D,L-lactide-co-glycolide) copolymer degradation products in rats

Poly (d,l-lactide-co-glycolide) (PLGA) copolymers are among the few synthetic polymers approved for human use, but the biocompatibility of PLGA-derived oligomers and particles remains questionable. Here, high molecular weight PLGA (Mwxa0=xa032,000) was radiolabeled with 125I in chloroform solution, and the body distribution of PLGA copolymer degradation products was examined following subcutaneous implantation of round 125I-PLGA films on the back of Sprague Dawley rats. Autoradiographic images of the PLGA implant taken at 2, 4, 6, 8, 10, and 12xa0weeks revealed that the central portion of the film degraded much more rapidly than the marginal portions. Examination of the body compartment distribution at these time points revealed that over one-half of the radioactivity was recovered from skin. The remaining radioactivity was concentrated in the blood, liver, and kidneys. Radioactivity steadily appeared in the blood and remained elevated up to 12xa0weeks after implantation, while the liver to kidney distribution began to decrease after 6xa0weeks. Cumulatively, these results indicate that the clearance of degraded particles and fragments from the implantation site is extremely delayed. Moreover, the degraded particles and fragments were selectively concentrated in the liver and kidneys, following release of degraded products into the bloodstream from the implantation site.

Tissular localization and excretion of intravenously administered silica nanoparticles of different sizes

The nanotoxicology as a new subdiscipline of nanotechnology needs to be studied in vivo. To do so, it is essential to understand certain pharmacological information of the nanoparticles in vivo. Silica nanoparticles (SiNPs) have been developed for a number of biomedical uses; however, research on their tissular localization and excretion has been limited. In this study, we analyzed the localization of intravenously administered SiNPs with sizes of 20 and 80xa0nm in liver and spleen and quantitatively investigated the excretion of SiNPs through urine and feces. The results of the tissular localization study showed that the SiNPs were located in liver evenly; however, they were mainly accumulated in the white pulp of spleen. The quantitative excretory assay found the renal excretion being the main excretion pathway of SiNPs and indicated that the accumulated excretory rate of 80xa0nm SiNPs through urine was higher than that of 20xa0nm SiNPs because of the higher hemoconcentration. Further analysis of radioactive substances in the excreta showed the convincing confirmatory evidence that the SiNPs of both the sizes of 20 and 80xa0nm could be excreted through urine. These results provide important information on in vivo distribution and excretion of SiNPs.

Study of Effect on Cell proliferation and Hemolysis of HAP and TCP Nanometer Particles

Hydroxyapatite (HAP) and tricalcium phosphate (TCP) nanoparticles (NPs) are in current use covering a wide range of medical applications, hence, it is indispensable to study the potential side effect acting on living organism, and to figure out the biocompatibility evaluation model of nanoparticles for standardization and methodology. In the present study, HAP and TCP NPs were selected and their diameters were within 30-80nm. Cytotoxicity in vitro was analyzed by agar overlay and direct contact exposure test was conducted to evaluate potential toxicity to SD rat macrophages, and hemolysis test of NPs was performed in compliance with ISO 10993-12 guidelines. The results showed that both HAP and TCP NPs could inhibit proliferation of macrophages when their concentration was reached to 20 µg/ml, and the extent of haemolysis would be increased more than 5% while 1000µg/ml NPs were contacted with rabbit blood cells. Furthermore, TCP NPs could induce obvious hemolysis reaction and inhibit proliferation of macrophages compared with group of HAP NPs at the same concentration.

Different Activities of Osteoblast and Bacteria on a Nanostructured Titanium Surface for Dental Implant

Insufficience of osteogenesis and antimicrobial effect have been still impacted the long term clinical success rate of dental implants. A nanostructured titanium surface prepared by hydrothermal treatment with H2O2 was evaluated on its osteoblastic viability and antibacterial effect. Samples were divided into 2 groups: untreated pure titanium surface (Ti) and a nanostructured titanium surface (NT). The antibacterial activities against S.mutans and C.albicans were measured by film applicator coating assay, as well as the live/dead bacteria stain. The osteoblastic viability was investigated by SEM and MTT assay. Results showed that the active microbia on NT was reduced at 24h (P<0.05) significantly according to the live/dead bacteria stain and film applicator coating assay, which could also enhance the osteoblast viability. Therefore, a nanostructured titanium surface exhibits good antibacterial activity on S.mutans and C.albicans, and promoting osteoblast viability, which will be a potential kind of dental implant material.

Injury on Blood Systems Caused by Silicon Dioxide Nanoparticles

Nano-sized silicon dioxide (SiO2) is widely utilized in artificial bone, artificial tooth, interventional catheters and drug delivery system，so it is imperative to study SiO2 NPs on the role of the body damage. Consulted with standard reference of GB/T16886, 20 and 80 nm SiO2 NPs were selected to prepare suspension (1mg/ml) for subacute systemic toxicity; 2000mg/ml suspension for MTT; and extracts (0.1g/ml) for hemolytic test. The results show that the hemolysis rate are all more than 5%, after its continuous injection of 2W nanoparticles into SD rats and New Zealand Rabbits, the alterations on the hemoglobin, hematocrit, mean corpuscular volume and other indicators have gained in blood routine test, and there was a marked inhibition on the L929 cells of SiO2 NPs. Therefore, these two kinds of particle size of SiO2 NPs have certain extent of injury effect on the blood system, and the contact time of NPs in the blood compatibility evaluation has play a more important role than the others.