The Influence of Biological Environment on the Silver-Coated Implants

The environment of the human body is very aggressive, containing among others bacteria, which contribute to the degradation of metal implants. Therefore sometimes implants are covered with nanometals to prevent development of aggressive bacteria. This paper deals with implants covered with nanosilver (15nm), which is antibacterial. The tested implants included: PE vein implant, an intramedullary implant made of stainless steel  and  brass implant for tracheotomy. The results showed an appearance of implants covered with silver as dependent on the type of bacteria: although silver significantly protected implants against some bacteria, a presence of some amounts of Staphylococcus aureus and Staphylococcus epidermidis was noticed after long term exposure in the human body. Only single bacteria could be observed on the surface of the tested materials. Such behavior is evidence, that silver coatings are effective for different form of materials in the presence of various bacteria, however, such behavior is related to form of  bacteria

The use of quartz crystal microbalance with dissipation (QCM-D) for studying nanoparticle-induced platelet aggregation

Interactions between blood platelets and nanoparticles have both pharmacological and toxicological significance and may lead to platelet activation and aggregation. Platelet aggregation is usually studied using light aggregometer that neither mimics the conditions found in human microvasculature nor detects microaggregates. A new method for the measurement of platelet microaggregation under flow conditions using a commercially available quartz crystal microbalance with dissipation (QCM-D) has recently been developed. The aim of the current study was to investigate if QCM-D could be used for the measurement of nanoparticle-platelet interactions. Silica, polystyrene, and gold nanoparticles were tested. The interactions were also studied using light aggregometry and flow cytometry, which measured surface abundance of platelet receptors. Platelet activation was imaged using phase contrast and scanning helium ion microscopy. QCM-D was able to measure nanoparticle-induced platelet microaggregation for all nanoparticles tested at concentrations that were undetectable by light aggregometry and flow cytometry. Microaggregates were measured by changes in frequency and dissipation, and the presence of platelets on the sensor surface was confirmed and imaged by phase contrast and scanning helium ion microscopy

Modified Nanoparticles as Potential Agents in Bone Diseases: Cancer and Implant-Related Complications

Materials sized 1–100 nm are the nanotechnology’s field of interest. Because of the unique properties such as the ability to penetrate biological barriers and a high surface to volume ratio, nanoparticles (NPs) are a powerful tool to be used in medicine and industry. This review discusses the role of nanotechnology in bone-related issues: osteosarcoma (bone cancer), the biocompatibility of the implants and implant-related infections. In cancer therapy, NPs can be used as (I) cytotoxic agents, (II) drug delivery platforms and (III) in thermotherapy. In implant-related issues, NPs can be used as (I) antimicrobial agents and (II) adjuvants to increase the biocompatibility of implant surface. Properties of NPs depend on (I) the type of NPs, (II) their size, (III) shape, (IV) concentration, (V) incubation time, (VI) functionalization and (VII) capping agent type

AgNPs-induced generation of nitrotyrosine in hFOB 1.19 and its inhibition by L-NIL.

<p>(A) A bar graph showing data as measured by ELISA; (B) Representative immunoblots. Data are expressed as means ± SD of 3 independent experiments. *p<0.05; **p<0.01 exposed cells v/s control or as indicated.</p

Molecular Mechanism of Silver Nanoparticles-Induced Human Osteoblast Cell Death: Protective Effect of Inducible Nitric Oxide Synthase Inhibitor

<div><p>Background</p><p>Silver nanoparticles (AgNPs) show strong antibacterial properties, making them excellent candidates to be used in orthopaedic repair and regeneration. However, there are concerns regarding the cytotoxicity of AgNPs and molecular mechanisms underlying AgNPs-induced bone cells toxicity have not been elucidated. Therefore, the aim of our study was to explore mechanisms of AgNPs-induced osteoblast cell death with particular emphasis on the role of nitric oxide (NO) generated by inducible nitric oxide synthase (iNOS).</p><p>Methods and Result</p><p>Silver nanoparticles used in this study were 18.3±2.6 nm in size, uncoated, spherical, regular shape and their zeta potential was -29.1±2.4 mV as measured by transmission electron microscopy (TEM) and zetasizer. The release of silver (Ag) from AgNPs was measured in cell culture medium by atomic absorption spectroscopy (AAS). The exposure of human osteoblast cells (hFOB 1.19) to AgNPs at concentration of 30 or 60 μg/mL for 24 or 48 hours, respectively resulted in cellular uptake of AgNPs and changes in cell ultrastructure. These changes were associated with apoptosis and necrosis as shown by flow cytometry and lactate dehydrogenase (LDH) assay as well as increased levels of pro-apoptotic Bax and decreased levels of anti-apoptotic Bcl-2 mRNA and protein. Importantly, we have found that AgNPs elevated the levels of nitric oxide (NO) with concomitant upregulation of inducible nitric oxide synthase (iNOS) mRNA and protein. A significant positive correlation was observed between the concentration of AgNPs and iNOS at protein and mRNA level (r = 0.837, r = 0.721, respectively; p<0.001). Finally, preincubation of osteoblast cells with N-iminoethyl-l-lysine (L-NIL), a selective iNOS inhibitor, as well as treating cells with iNOS small interfering RNAs (siRNA) significantly attenuated AgNPs-induced apoptosis and necrosis. Moreover, we have found that AgNPs-induced cells death is not related to Ag dissolution is cell culture medium.</p><p>Conclusion</p><p>These results unambiguously demonstrate that increased expression of iNOS and generation of NO as well as NO-derived reactive species is involved in AgNPs-induced osteoblast cell death. Our findings may help in development of new strategies to protect bone from AgNPs-induced cytotoxicity and increase the safety of orthopaedic tissue repair.</p></div

AgNPs-induced necrosis in hFOB 1.19 cells and protective effect of L-NIL.

<p>Nec-1 failed to protect cells from AgNPs-induced cell death. Data are expressed as means ± SD of 3 independent experiments. *p<0.05; ***p<0.001 exposed cells v/s control or as indicated.</p

Pretreatment of hFOB 1.19 with L-NIL attenuated AgNPs-induced cell death.

<p><b>A representative dot plot of flow cytometry.</b> A representative dot plot of flow cytometry. AgNPs induced apoptosis and necrosis in hFOB 1.19 cells an effect attenuated by L-NIL. Viable cells are shown in the lower left field (low Annexin V and PI staining; AV- PI-). The lower right field (AV+ PI-) represents the apoptotic cells, and the higher right field (AV+ PI+) indicates late apoptotic/necrotic cells. The higher left field (AV- PI+) shows the dead cells. L-NIL significantly attenuated number of apoptotic and dead cells.</p

The TEM examination of hFOB 1.19.

<p>(A) The ultrastructural features of a control cell; mitochondria (M), nucleus (N), Golgi complex (Ga); (B-C) Cells exposed to AgNPs 30 μg/mL for 24 h. cell. (B) AgNPs are found within the cell (arrows). Micrographs show vacuoles (V) with randomly oriented AgNPs of quite regular morphology (arrows). The well-developed Golgi complex (Ga) is located in the cytoplasm in perinuclear areas. (C) Cells exposed to AgNPs 30 μg/mL for 24 h show swelling of the endoplasmic reticulum. Ribosomes may have dissociated from the endoplasmic reticulum (RER) and the cytoplasm is filled with free ribosomes. The nucleus (N) presents a normal aspect.</p

The summary characteristics of AgNPs.

<p>The summary characteristics of AgNPs.</p

AgNPs-induced apoptosis in hFOB 1.19 cells and protective effect of L-NIL.

<p>(A) AgNPs-induced apoptosis, (B) Bax, Bcl-2 protein and (C) Bax, Bcl-2 mRNA levels. L-NIL significantly attenuated: (A) number of apoptotic cells, (B) Bax protein, (C) mRNA level and significantly increased: (B) Bcl-2 protein, (C) mRNA level. Data are expressed as means ± SD of 3 independent experiments. *p<0.05; **p<0.01; ***p<0.001 exposed cells v/s control or as indicated.</p