Controlling the Size of Thiolated Organosilica Nanoparticles

Abstract

Nanoparticle characteristics, including their size, are governed by the reagents employed and the reaction parameters. Here, we systemically vary the catalyst, oxygen content, temperature, and solvent to modify the size and zeta-potential of thiolated organosilica nanoparticles. The particles were synthesized by self-condensation of 3-mercaptopropyltrimethoxysilane in a range of organic solvents in contact with oxygen, with NaOH and other catalysts. The particle size increased with increasing reaction temperature (70 ± 1 nm at 50 °C; 50 ± 1 nm at room temperature) but decreased when air was bubbled through the reaction mixture compared to no bubbling. A significant decrease in the particle size was seen when increasing the dielectric constant of the solvent and when increasing the catalyst concentration; from these, we provide empirical equations that can be used to design particle sizes by manipulating the dielectric constant of the solvent (or cosolvents) or by varying the NaOH catalyst concentration when dimethylsulfoxide is the selected solvent.

Silica Nanoparticles in Transmucosal Drug Delivery

“…Later, Al Mahrooqi et al [43] investigated the effects of various parameters, including catalyst type and concentration, MPMS concentration and solvent type on the physicochemical properties of these thiolated silica nanoparticles. From the dynamic light scattering (DLS) analysis, it was found that the size of the nanoparticles decreased from~290 nm to~50 nm with increasing NaOH concentration (0.05 M up to 0.5 M), but a further increase in the concentration of NaOH (0.5 to 0.9 M) did not significantly change the size of the nanoparticles.…”

“…However, a lower concentration of MPMS (0.04 M) resulted in an increase in the size of the nanoparticles. Further experiments using different organic solvents revealed that increasing the dielectric constant of the solvents decreased the nanoparticles size wherein nanoparticles synthesised using DMSO (with a dielectric constant of 47) had the smallest size (45 ± 3 nm) and low polydispersity index (0.181) [43]. Clearly, the ability to control the physicochemical properties of these thiolated silica nanoparticles can have a significant impact on the behaviour (e.g., mucoadhesion and biodistribution) of these nanoparticles in biological environments.…”

Thiolated and PEGylated silica nanoparticle delivery to hair follicles

“…The mean and standard deviation of particle size, polydispersity, and ᶚ-potential were calculated. The thiol group content in nanoparticles was determined by Ellman's assay according to a previously published method (Al Mahrooqi et al, 2018).…”

Thiolated Nanoparticles for Biomedical Applications: Mimicking the Workhorses of Our Body

“…The smallest nonporous particles (less than 50 nm) were obtained when NaOH was used as the catalyst and the self‐condensation of MPTS was conducted in dimethyl sulfoxide (DMSO) with air bubbling. [ 91 , 92 , 93 ] Air bubbling was facilitating the formation of disulfide bonds between MPTS monomer molecules as illustrated in Figure 6 . Furthermore, they functionalized the surface of developed NPs with PEG or poly(2‐alkyl‐2‐oxazolines) and demonstrated their mucus‐penetrating properties [ 94 , 95 ]…”