Silica Particles: A Novel Drug‐Delivery System

Abstract

In recent decades, significant advances in drug‐delivery systems have enabled more effective drug administration. To deliver drugs to specific organs, a range of organic systems (e.g., micelles, liposomes, and polymeric nanoparticles) have been designed. They suffer from limitations, including poor thermal and chemical stability, and rapid elimination by the immune system. In contrast, silica particles offer a biocompatible, stable, and “stealthy” alternative. Bioactive molecules can be easily encapsulated within silica particles by combining sol–gel polymerization with either spray‐drying or emulsion chemistry. Spray‐drying faces challenges, including low yield, surface segregation, and size limitations. In contrast, sol–gel emulsions enable the production of nanoparticles with homogeneous drug distribution, and permit ambient temperature processing, necessary for handling biologicals. Independent control of the size and release rate can be readily achieved. Preliminary in‐vivo experiments reveal enhanced blood stability of the nanoparticles, which, coupled with sustained release of anti‐tumor agents, show good potential for cancer treatment.

Improved Biocompatibility and Pharmacokinetics of Silica Nanoparticles by Means of a Lipid Coating: A Multimodality Investigation

“…38 The accumulation of bare silica particles in mouse and rat lungs after tail vein injection has been observed previously and was attributed to particle aggregation. 6,24,37 Finally, we note that the amount of particle aggregation probably plays a crucial role in the way particles are cleared from organs and the body. Although not studied here, it is possible that well-dispersed particles are better excreted from the body.…”

“…6,37 This aggregation is accelerated through the absorption of opsonins (markers which enhance endocytosis), which is followed by extravascularisation via the reticuloendothelial system (RES). 6,38,39 Consequently, these nanoparticles suffer from poor pharmacokinetics, such as short blood circulation half-life values and accumulation in the lung capillary vessels when administered intravenously. 6,37 To deal with these limitations, two strategies have been developed aimed at increasing the biocompatibility of silica particles.…”

“…Although liver clearance of bare silica particles is not well understood, it has been observed previously for 50 and 250 nm bare silica particles. 6 Quantitative analysis of the organ distribution of the particles was done by ICP-MS cadmium content determination in organs from control mice and mice sacrificed 1, 4, and 24 h postinjection of the nanoparticles (n ) 1 for each point and particle, Figure 6). Cadmium determinations allowed for comparison between the lipid-coated and bare silica particles since both types of particle contain equal amounts of this element, while comparison on the basis of gadolinium would fail due to the absence of Gd-DTPA-DSA lipid on bare silica particles.…”

Silica‐Coated Metal Nanoparticles

“…[29] By making use of its rich chemistry, [2] colloidally stable silicacoated nanoparticles can be more readily surface-functionalized with amino-, mercapto-, carboxy-, and aldehyde-terminated silanes than small ligand-coated gold nanoparticles for bio-conjugation and diverse biomedical applications including colorimetric diagnostics, photothermal therapy, surface enhanced Raman scattering (SERS) detection, and so forth.…”

Effect of Silica Surface Properties on the Formation of Multilayer or Submonolayer Protein Hard Corona: Albumin Adsorption on Pyrolytic and Colloidal SiO2 Nanoparticles

“…1 In the case of beneficial effects, a typical example is Hench bioglasses. 2 More recently, this scenario has been enriched by actual or potential uses of silica nanoparticles (NPs) in nanomedicine, beginning with seminal research works carried out in the in the first decade of the 20th century, dealing with the use of SiO 2 as drug-delivery system, 3 or as the basis for the fabrication of engineered multifunctional systems. 4 In general, the SiO 2 NPs in the huge amount of subsequent investigations in the fields of nanomedicine and nanobiotechnology can be classified into two main categories: porous (typically mesoporous) [5][6][7] and nonporous.…”