Silica nanoparticles as sources of silicic acid favoring wound healing in vitro.

There is good evidence that certain silicon-containing materials promote would healing and their common feature is the delivery of orthosilicic acid (Si(OH)) either directly or following metabolism. In this respect, amorphous silica nanoparticles (NP), which dissolve in aqueous environments releasing up to 2mM orthosilicic acid, may be appropriate 'slow release' vehicles for bioactive silicon. Here we studied the impact of silica NP suspensions (primary particles∼10nm) in undersaturated conditions (below 2mM Si) with differing degrees of surface charge and dissolution rate on human dermal fibroblasts (CCD-25SK cells) viability, proliferation and migration in a cellular wound model.

Nanometric emulsions encapsulating solid particles as alternative carriers for intracellular delivery.

Aim: Formulate nanometric oil droplets for encapsulating solid nanoparticles and assess their interactions with cells.

Materials & Methods: Soybean oil droplets, stabilized by Pluronic F68 surfactant, incorporating hydrophobically modified fluorescent silica, nanoparticles were obtained. Cytotoxicity over time, internalization, subsequent intracellular localization and internalization pathways were assessed by microscopy (fluoresence and TEM) in vitro with HeLa cells.

Phagocytosis of immunoglobulin-coated emulsion droplets.

Phagocytosis by macrophages represents a fundamental process essential for both immunity and tissue homeostasis. The size of targets to be eliminated ranges from small particles as bacteria to large objects as cancerous or senescent cells. Most of our current quantitative knowledge on phagocytosis is based on the use of solid polymer microparticles as model targets that are well adapted to the study of phagocytosis mechanisms that do not involve any lateral mobility of the ligands, despite the relevance of this parameter in the immunological context.

Behaviour of silica nanoparticles in dermis-like cellularized collagen hydrogels.

A model of the fate of colloidal silica in the dermis was designed based on the diffusion of fluorescent silica nanoparticles through collagen hydrogels. The diffusion process was found to depend on particle size (10-200 nm) and surface charge, as well as on collagen concentration (1.5-5 mg mL).

Introduction of disulfide bridges within silica nanoparticles to control their intra-cellular degradation.

Incorporation of disulfide bridges in the core structure of silica nanoparticles modifies their intracellular fate within dermal fibroblasts, especially influencing their degradation pathway.

Long-term fate of silica nanoparticles interacting with human dermal fibroblasts.

The long-term fate of fluorescent non-porous FITC-SiO(2) nanoparticles of various sizes (10-200 nm) and charge is studied in the presence of human dermal fibroblasts. Particle aggregates are formed in the culture medium and uptaken, at least partially, by macropinocytosis. The smallest particles have a strong impact on cell viability and genotoxic effects can be observed for negatively-charged colloids 10 nm in size.

In vitro studies and preliminary in vivo evaluation of silicified concentrated collagen hydrogels.

Hybrid and nanocomposite silica-collagen materials derived from concentrated collagen hydrogels were evaluated in vitro and in vivo to establish their potentialities for biological dressings. Silicification significantly improved the mechanical and thermal stability of the collagen network within the hybrid systems. Nanocomposites were found to favor the metabolic activity of immobilized human dermal fibroblasts while decreasing the hydrogel contraction.