Synthesis of water-degradable silica nanoparticles from carbamate-containing bridged silsesquioxane precursor

Abstract

Silica nanoparticles (SNPs) are attractive for applications for the delivery of drugs and as imaging agents due to their ease of synthesis and scale up, robust structure, and controllable size and composition. Degradability is one important factor that limits biomedical applications of SNPs. With this in mind, we designed, prepared and characterized novel hydrolysable organosilica nanoparticles (ICPTES-Sorbitol SNPs). These particles were prepared by co-condensation of tetraethoxysilane with a bridged sorbitol-based silsesquioxane precursor containing carbamate linkages. The non-porous spherical ICPTES-Sorbitol SNPs became porous after they were placed in an aqueous environment as a result of the hydrolysis of carbamate bonds and were completely degraded upon prolonged exposure to water. The rate of degradation depended on the pH of the solution, with nanoparticles degrading slower at pH 2 than at pH 4 or pH 7. The degradation was demonstrated by transmission electron microscopy, nitrogen desorption analysis and solution analytical techniques such as ICP-MS and molybdenum blue assay, which was also used to follow the dissolution of ICPTES-Sorbitol SNPs.

Mesoporous organosilica nanoparticles: Degradation strategies and application in tumor therapy

“…Gao et al first reported hollow MONs with pH-triggered degradation based on the hybridization of sorbitol moiety into the silica framework. 45 A sorbitol-bridged alkoxysilane was synthesized by grafting of deliquescent sorbitol to 3-isocyanatopropyltriethoxysilane (ICPTES), and the pH-sensitive hollow MONs were obtained by the hydrolysis and condensation of the mixture containing ICPTES-sorbitol bridged alkoxysilane and TEOS. The results showed that hollow MONs containing sorbitol moiety could occur the hydrolysis at neutral pH and degrade after 3 months, but they were observed to be broken into irregularly spherical pieces only after 3 weeks at pH 4.…”

Multilamellar mesoporous silica nanoparticles using a cationic co-surfactant dual-templating method

“…Silica is an excellent material for nanoparticle synthesis because of biocompatibility, post-grafting functionalization, inertness under many conditions, easily to form structured particles and biodegradability. The dissolution of silica consists of three parts: (1) water is adsorbed into the siloxane mesh, (2) siloxane is gradually hydrolysed into silanols and (3) an ion-exchange process, which uses nucleophilic attacks of hydroxyl groups, leads eventually to the leaching of silicic acid (23). The end products diffuse through the bloodstream of the lymph lobe to be eventually cleared in urine.…”

Trends in Degradable Mesoporous Organosilica-Based Nanomaterials for Controlling Drug Delivery: A Mini Review

“…For the delivery of anticancer drugs, the degradation of silica nanocarriers in an aqueous environment might be attractive. In that direction, non-porous water-degradable silica nanoparticles were prepared using a bridged sorbitol-based silsesquioxane precursor containing carbamate linkages [ 39 ]. Here, the organosilane-bridge containing precursor was prepared from sorbitol moieties reacted with (3-isocyanatepropyl)triethoxysilane (ICPTES).…”