In vitro evaluation of the internalization and toxicological profile of silica nanoparticles and submicroparticles for the design of dermal drug delivery strategies

Low frequency vibrating magnetic field-triggered magnetic microspheres with a nanoflagellum-like surface for cancer therapy

Background

The magneto-mechanical force killing cancer cells is an interesting and important strategy for cancer therapy.

Results

Novel magnetic microspheres composed of a Fe3O4 nanocore, a bovine serum albumin (BSA) matrix, and a rod-like SiO2 nanoshell, which had flagellum-like surface for force-mediated cancer therapy were developed. One such magnetic microsphere (Fe3O4/BSA/rSiO2) at a cancer cell (not leave the cell surface) under a low frequency vibrating magnetic field (VMF) could generate 6.17 pN force. Interestingly, this force could induce cancer cell to generate reactive oxygen species (ROS). The force and force-induced ROS could kill cancer cells. The cell killing efficiency of Fe3O4/BSA/rSiO2 exposed to a VMF was enhanced with increasing silica nanorod length, and the microspheres with straight nanorods exhibited stronger cell killing ability than those with curled nanorods. Fe3O4/BSA/rSiO2 triggered by a VMF could efficiently inhibit mouse tumor growth, while these microspheres without a VMF had no significant effect on the cell cycle distribution, cell viability, tumor growth, and mouse health.

Conclusions

These microspheres with unique morphological characteristics under VMF have great potential that can provide a new platform for treating solid tumors at superficial positions whether with hypoxia regions or multidrug resistance.

Potential of chitosan/alginate nanoparticles as a non-viral vector for gene delivery: Formulation and optimization using D-optimal design

Chitosan/alginate (Chi/Alg) nanoparticles as a non-viral vector for the Smad4 encoding plasmid were optimized utilizing D-optimal design based on the nanoparticles/plasmid ratio, Chi/Alg MW, and preparation method type. Following the optimization and validation of the best formula, morphology studies and FTIR measurements were performed to evaluate the optimized Chi/Alg/S NPs. Toxicity (MTT assay) and transfection studies were performed for the best formula in comparison with Lipofectamine 2000, and Polyethyleneimine (PEI) and evaluated using Green Fluorescence Protein (GFP) assay, Flow cytometry, and RT-PCR. The model predicted a particle size of 111 nm, loading efficacy (LE) of 43%, cumulative release (CMR) of 39%, the ζ-potential of +50 mV, and PDI of 0.13. The predicted point condition was as follows: NP ratio = 13, Chi/Alg MW ratio = 2.35, and preparation method type = 1. Microscopic findings revealed that the shape of nanoparticles was spherical. The Chi/Alg/S nanoparticles showed no toxicity and transfection efficacy of 29.9% was observed in comparison with Lipofectamine (35.5%) and PEI (30.9%).

Micron-sized iron oxide particles for both MRI cell tracking and magnetic fluid hyperthermia treatment

Iron oxide particles (IOP) are commonly used for Cellular Magnetic Resonance Imaging (MRI) and in combination with several treatments, like Magnetic Fluid Hyperthermia (MFH), due to the rise in temperature they provoke under an Alternating Magnetic Field (AMF). Micrometric IOP have a high sensitivity of detection. Nevertheless, little is known about their internalization processes or their potential heat power. Two micrometric commercial IOP (from Bangs Laboratories and Chemicell) were characterized by Transmission Electron Microscopy (TEM) and their endocytic pathways into glioma cells were analyzed. Their Specific Absorption Rate (SAR) and cytotoxicity were evaluated using a commercial AMF inductor. T2-weighted imaging was used to monitor tumor growth in vivo after MFH treatment in mice. The two micron-sized IOP had similar structures and r2 relaxivities (100 mM-1 s-1) but involved different endocytic pathways. Only ScreenMAG particles generated a significant rise in temperature following AMF (SAR = 113 W g-1 Fe). After 1 h of AMF exposure, 60% of ScreenMAG-labeled cells died. Translated to a glioma model, 89% of mice responded to the treatment with smaller tumor volume 42 days post-implantation. Micrometric particles were investigated from their characterization to their intracellular internalization pathways and applied in one in vivo cancer treatment, i.e. MFH.

The Size-dependent Cytotoxicity of Amorphous Silica Nanoparticles: A Systematic Review of in vitro Studies

With the increasing production and application of engineered amorphous silica nanoparticles (aSiNPs), people have more opportunities to be exposed to aSiNPs. However, the knowledge of its adverse health effects and related mechanisms is still limited, compared with the well-studied crystalline micron-sized silica. Since small differences in the physical–chemical properties of nanoparticles could cause significant differences in the toxic effect, it is important to distinguish how these variations influence the outcoming toxicity. Notably, particle size, as one of the essential characterizations of aSiNPs, is relevant to its biological activities. Thus, the aim of this systematic review was to summarize the relationship between the particle size of aSiNPs and its adverse biological effects. In order to avoid the influence of complicated in vivo experimental conditions on the toxic outcome, only in vitro toxicity studies which reported on the cytotoxic effect of different sizes aSiNPs were included. After the systematic literature retrieval, selection, and quality assessment process, 76 eligible scientific papers were finally included in this review. There were 76% of the studies that concluded a size-dependent cytotoxicity of aSiNPs, in which smaller-sized aSiNPs possessed greater toxicity. However, this trend could be modified by certain influence factors, such as the synthetic method of aSiNPs, particle aggregation state in cell culture medium, toxicity endpoint detection method, and some other experimental conditions. The effects of these influence factors on the size-dependent cytotoxicity of aSiNPs were also discussed in detail in the present review.

Acute cytotoxic effects of silica microparticles used for coating of plastic blood-collection tubes on human periosteal cells

Because of its simple operation, platelet-rich fibrin (PRF) is becoming more popular than the original form, platelet-rich plasma (PRP), in regenerative dentistry. PRF preparation requires plain glass blood-collection tubes, but not either anticoagulants or coagulation factors. However, such glass tubes designed for laboratory testing are no longer commercially available. Although several glass tubes specifically designed for PRF preparation are available, many clinicians prefer to obtain stably supplied substitutes, such as silica-coated plastic tubes produced by major medical device companies. The quality of PRF prepared by silica-coated tubes has not been assessed and we previously reported significant contamination of silica microparticles in the resulting PRF matrix and alerted clinicians against the use for PRF preparation. To further assess the biosafety of the silica microparticles, we presently examined their effects on human normal periosteal cells derived from alveolar bone. The periosteal cells were obtained from explant cultures of small periosteal tissues obtained from healthy donors. Silica microparticles were obtained from silica-coated tubes and added to cell cultures. Cellular responses were monitored using a tetrazolium assay, phase-contract inverted microscopy, an immunofluorescence method, and scanning electron microscopy. Silica microparticles adsorbed onto the cell surface with seemingly high affinity and induced apoptosis, resulting in significant reduction of cell proliferation and viability. These findings suggest that silica microparticles contained in plastic tubes for the purpose of blood coagulation are hazardous for various cell types around sites where silica-contaminated PRF matrices are implanted.

Cytotoxicity, genotoxicity, transplacental transfer and tissue disposition in pregnant rats mediated by nanoparticles: the case of magnetic core mesoporous silica nanoparticles

Whether in the cosmetic or as therapeutic, the use of nanoparticles has been increasing and taking on global proportion. However, there are few studies about the physical potential of long-term use or use in special conditions such as chronic, AIDS, pregnant women and other special health circumstances. In this context, the study of the mutagenicity and the transplacental passage represents an important and reliable model for the primary evaluation of potential health risks, especially maternal and child health. In this study we performed mutagenicity, cytotoxic and transplacental evaluation of magnetic core mesoporous silica nanoparticles, radiolabeled with ^99mTc for determination of toxicogenic and embryonic/fetuses potential risk in animal model. Magnetic core mesoporous silica nanoparticles were produced and characterized by obtaining nanoparticles with a size of (58.9 ± 8.1 nm) in spherical shape and with intact magnetic core. The 99 m Tc radiolabeling process demonstrated high efficacy and stability in 98% yield over a period of 8 hours of stability. Mutagenicity assays were performed using Salmonella enteric serovar Typhimurium standard strains TA98, TA100 and TA102. Cytotoxicity assays were performed using WST-1. The transplacental evaluation assays were performed using the in vivo model with rats in two periods: embryonic and fetal stage. The results of both analyzes corroborate that the nanoparticles can i) generate DNA damage; ii) generate cytotoxic potential and iii) cross the transplantation barrier in both stages and bioaccumulates in both embryos and fetuses. The results suggest that complementary evaluations should be conducted in order to attest safety, efficacy and quality of nanoparticles before unrestricted approval of their use.

In Vitro and In Vivo Short-Term Pulmonary Toxicity of Differently Sized Colloidal Amorphous SiO₂

In vitro prediction of inflammatory lung effects of well-dispersed nanomaterials is challenging. Here, the in vitro effects of four colloidal amorphous SiO₂ nanomaterials that differed only by their primary particle size (9, 15, 30, and 55 nm) were analyzed using the rat NR8383 alveolar macrophage (AM) assay. Data were compared to effects of single doses of 15 nm and 55 nm SiO₂ intratracheally instilled in rat lungs. In vitro, all four elicited the release of concentration-dependent lactate dehydrogenase, β-glucuronidase, and tumor necrosis factor alpha, and the two smaller materials also released H₂O₂. All effects were size-dependent. Since the colloidal SiO₂ remained well-dispersed in serum-free in vitro conditions, effective particle concentrations reaching the cells were estimated using different models. Evaluating the effective concentration–based in vitro effects using the Decision-making framework for the grouping and testing of nanomaterials, all four nanomaterials were assigned as “active.” This assignment and the size dependency of effects were consistent with the outcomes of intratracheal instillation studies and available short-term rat inhalation data for 15 nm SiO₂. The study confirms the applicability of the NR8383 AM assay to assessing colloidal SiO₂ but underlines the need to estimate and consider the effective concentration of such well-dispersed test materials.