One-Pot Bifunctionalization of Silica Nanoparticles Conjugated with Bioorthogonal Linkers: Application in Dual-modal Imaging

Covalent surface modification of silica nanoparticles (SNPs) offers great potential for the development of multimodal nanomaterials for biomedical applications. Herein, we report the synthesis of covalently conjugated bifunctional SNPs and...

Three-dimensional direct visualization of silica dispersion in polymer-based composites

We present a novel strategy for realizing the three-dimensional direct visualization of silica dispersion by the fluorescence modification of a silica filler.

Silica-based nanoparticles are efficient delivery systems for temoporfin

BACKGROUND

Drug targeting using functionalized nanoparticles to advance their transport to the dedicated site became a new standard in novel anticancer methods Anticancer photodynamic therapy also takes benefit from using nanoparticles by means of increasing targeting efficiency and decreased side effect. With this in mind, the silica-based nanoparticles, as drug delivery systems for the second-generation photosensitizer 5,10,15,20-tetrakis(m-hydroxyphenyl) chlorin (temoporfin) were developed.

METHODS

In order to determine the stability and therapeutic performance of the selected nanomaterials in physiological fluids, their physicochemical properties (i.e. size, polydispersity, zeta potential) were measured by dynamic light scattering technique and the diameter and the morphology of the individual particles were visualized by a transmission electron microscopy. Their efficacy was compared with commercial temoporfin formulation in terms of in vitro phototoxicity in 4T1 (murine mammary carcinoma) and of in vivo anticancer effect in Nu/Nu mice bearing MDA-MB-231 tumors.

RESULTS AND CONCLUSIONS

The two types of silica nanoparticles, porous and non-porous and with different surface chemical modification, were involved and critically compared within the study. Their efficacy was successfully demonstrated and was shown to be superior in comparison with commercial temoporfin formulation in terms of in vitro phototoxicity and cellular uptake as well as in terms of in vivo anticancer effect on human breast cancer model. Temoporfin-loaded silica nanoparticles also passed through the blood-brain barrier showing potential for the treatment of brain metastases.

Silica nanoparticles: preparation, characterization and in vitro/in vivo biodistribution studies

BACKGROUND

The current progress in pharmaceutical nanotechnology field has been exploited in the design of functionalized radiolabelled nanoparticles that are able to deliver radionuclides in a selective manner to improve the outcome of diagnosis and treatment. Silica nanoparticles (SNPs) have been widely developed for biomedical applications due to their high versatility, excellent functional properties and low cost production, with the possibility to control different topological parameters relevant for multidisciplinary applications.

PURPOSE

The aim of the present study was to characterize and evaluate both in vitro, by microscopy techniques, and in vivo, by scintigraphic imaging, the biodistribution of silica nanostructures derivatives (Cy5.5 conjugated SNPs and (99m)Tc radiolabelled SNPs) to be applied as radiotracers in biomedicine.

METHODS

SNPs were synthesized by hydrolysis and condensation of silicon alkoxides, followed by surface functionalization with amino groups available for fluorescent dye and radiolabelling possibility.

RESULTS

Our data showed the particles size distribution (200-350 nm), the surface charge (negative for bare and fluorescent SNPs and positive for amino SNPs), polydispersity index (broad distribution), the qualitative composition and the toxicity assessments (safe material) that made the obtained SNPs candidates for in vitro/in vivo studies. A high uptake of fluorescent SNPs in all the investigated organs was evidenced by confocal microscopy. The (99m)Tc radiolabelled SNPs biodistribution was quantified in the range of 12-100% counts/g organ using the scintigraphic images.

CONCLUSIONS

The obtained results reveal improved properties, namely, reduced toxicity with a low level of side effects, an improved biodistribution, high labelling efficiency and stability of the radiolabelled SNPs with potential to be applied in biomedical science, particularly in nuclear medicine as a radiotracer.

The impact of aminated surface ligands and silica shells on the stability, uptake, and toxicity of engineered silver nanoparticles

Inherent nanomaterial characteristics, composition, surface chemistry, and primary particle size, are known to impact particle stability, uptake, and toxicity. Nanocomposites challenge our ability to predict nanoparticle reactivity in biological systems if they are composed of materials with contrasting relative toxicities. We hypothesized that toxicity would be dominated by the nanoparticle surface (shell vs core), and that modulating the surface ligands would have a direct impact on uptake. We exposed developing zebrafish (Danio rerio) to a series of ~70 nm amine-terminated silver nanoparticles with silica shells (AgSi NPs) to investigate the relative influence of surface amination, composition, and size on toxicity. Like-sized aminated AgSi and Si NPs were more toxic than paired hydroxyl-terminated nanoparticles; however, both AgSi NPs were more toxic than the Si NPs, indicating a significant contribution of the silver core to the toxicity. Incremental increases in surface amination did not linearly increase uptake and toxicity, but did have a marked impact on dispersion stability. Mass-based exposure metrics initially supported the hypothesis that smaller nanoparticles (20 nm) would be more toxic than larger particles (70 nm). However, surface area-based metrics revealed that toxicity was independent of size. Our studies suggest that nanoparticle surfaces play a critical role in the uptake and toxicity of AgSi NPs, while the impact of size may be a function of the exposure metric used. Overall, uptake and toxicity can be dramatically altered by small changes in surface functionalization or exposure media. Only after understanding the magnitude of these changes, can we begin to understand the biologically available dose following nanoparticle exposure.

Nonporous Silica Nanoparticles for Nanomedicine Application

Nanomedicine, the use of nanotechnology for biomedical applications, has potential to change the landscape of the diagnosis and therapy of many diseases. In the past several decades, the advancement in nanotechnology and material science has resulted in a large number of organic and inorganic nanomedicine platforms. Silica nanoparticles (NPs), which exhibit many unique properties, offer a promising drug delivery platform to realize the potential of nanomedicine. Mesoporous silica NPs have been extensively reviewed previously. Here we review the current state of the development and application of nonporous silica NPs for drug delivery and molecular imaging.

Assessment of uptake and toxicity of fluorescent silica nanoparticles in zebrafish (Danio rerio) early life stages

In this study, we determined uptake and toxicity of fluorescent core-shell silica nanoparticles (FSNP) in early life stages of zebrafish. For this purpose fluorescent Ru@SiO2 nanoparticles with average size of ∼200 nm encapsulating [Ru(bpy)3](2+)Cl2 dye (excitation wavelength λ(exci)=488 nm), and Cy5.5@SiO2 with average size of ∼60 nm (λ(exci)=700 nm) were synthesized. The FSNP were highly luminescent. Field emission SEM analysis showed monodispersed dual-shell Ru@SiO2 nanoparticles of ∼200 nm size. Zebrafish embryos were exposed less than 6h post-fertilization (hpf) to the ∼60 and ∼200 nm FSNP at concentrations between 0.0025 and 200mg/L in 24-well plates for up to 96 hpf. The concentrations were analysed using an Fourier transform infra-red (FTIR) technique. Uptake of FSNP by embryos was monitored using transmission and confocal fluorescence microscopy. Toxicity was assessed by mortality, hatching time and success, and by morphological alterations. The ∼60 and ∼200 nm-sized FSNP and/or aggregates were adsorbed on the chorion of eggs. Uptake and translocation in embryos was not observed, but nanoparticle uptake not detectable by confocal microscopy may have occurred. Hatching time and hatching success were not affected. No mortality or deformities occurred. These nanoparticles and/or aggregates mainly accumulate on the chorion of embryos and exhibit no overt embryotoxicity.