Controlling particle size in the Stöber process and incorporation of calcium

Abstract

The Stӧber process is commonly used for synthesising spherical silica particles. This article reports the first comprehensive study of how the process variables can be used to obtain monodispersed particles of specific size. The modal particle size could be selected within in the range 20 -500 nm. There is great therapeutic potential for bioactive glass nanoparticles, as they can be internalised within cells and perform sustained delivery of active ions. Biodegradable bioactive glass nanoparticles are also used in nanocomposites. Modification of the Stӧber process so that the particles can contain cations such as calcium, while maintaining monodispersity, is desirable. Here, while calcium incorporation is achieved, with a homogenous distribution, careful characterisation shows that much of the calcium is not incorporated. A maximum of 10 mol% CaO can be achieved and previous reports are likely to have overestimated the amount of calcium incorporated.

ZnO quantum dots modified bioactive glass nanoparticles with pH-sensitive release of Zn ions, fluorescence, antibacterial and osteogenic properties

“…The challenge to produce highly dispersed and uniform BGN in the conventional one-step sol-gel method is that the addition of salt precursors may destabilize the nanoparticles by changing their surface charge. 30,51 This destabilization could then lead to the aggregation and non-uniformity of BGN. For the achievement of highly dispersed and uniform BGN, the processing parameters, e.g.…”

“…Alternatively, post modification of silica nanoparticles or binary BGN to introduce metallic ions has been shown to be able to avoid the aggregation of nanoparticles. 44,51 In this study, ZnO QDs were used as modification agents to introduce Zn ions. The modification was based on electrostatic interaction that could retain the structure and properties of the involved components.…”

Influence of the initial chemical conditions on the rational design of silica particles

“…In the example of Sato-Berru et al [22], they went beyond 60 wt% of water, but overlooked the miscibility gap that occurred at those higher water contents.

Fig. 1Particle size relation to water content, as reported by Sato-Berru et al [22], Bogush et al [11] and Greasley et al [33]. The data was replotted in wt% of water for this graph

…”

“…Particle size relation to water content, as reported by Sato-Berru et al [22], Bogush et al [11] and Greasley et al [33]. The data was replotted in wt% of water for this graph…”

Fabrication of Hollow Silica Particles Using a Self-Assembled Polyethylene Granule as a Template

“…Silica particle size on the granule was measured from the SEM images and displayed Journal of Nanomaterials in Figure 4(e) as a function of water concentration. It increased with water content where the size was~50 nm at 0.82 M water and reached~200 nm at 7.2 M. This behavior is similar to colloidal silica particle growth in terms of water concentration [37]. At 0.5 hr,~50 nm silica particle was coated on the surface and d of HSP was found to bẽ 190 nm.…”