Effect of preparation conditions on the properties of microspheres prepared using an emulsion-solvent extraction process

Sacrificial gelatin microspheres for tissue engineering applications

“…Furthermore, the mean diameters of cell-laden microspheres (tDGMC) decreased with higher stirring speed as shown inFigure 5-2D. These observations were similar to other reports in emulsion-derived microparticles[157][158][159]261].It was also observed fromFigure 5-2A-C that higher initial speed resulted in more empty microspheres (light grey, without cells): approximately 12%, 32% and 41% of total microspheres did not contain cells at respective stirring speeds of 350, 500 and 650 rpm. This may be attributed to probability; assuming an evenly distributed cell-gelatin suspension, as diameter and hence volume of gelatin droplet increases, the probability of cells being present in the droplet increases.…”

“…Increasing the stirring speed (usually defined in terms of revolutions per minute, rpm) increases the shear force, which translates to a decrease in microsphere size [155,158]. In Heiskanen's study, the mean diameter of microspheres increased from 19.1 µm to 40.5 µm as the stirring speed decreased from 600 rpm to 450 rpm [157]. Another study observed an increase in mean diameter of collagen microspheres from 75 µm to 182 µm when stirring speed was decreased from 1000 rpm to 600 rpm [122].…”

“…Many factors play a part in determining the size and distribution of microspheres: size of vessel, the volumetric ratio of both phases, viscosity of each phase (related to polymer concentration as well), stirring speed, presence and concentration of surfactant [157][158][159]. Increasing the stirring speed (usually defined in terms of revolutions per minute, rpm) increases the shear force, which translates to a decrease in microsphere size [155,158].…”

Influences of Stirring Speed and Post Annealing Temperature on the Properties of Zinc Oxide Colloid Prepared by Sol-Gel Spin Coating Method

“…Higher stirring speed resulted in smaller size ZnO colloid due to the increment of intensification of the micromixing in sol-gel process. The incur the rise of mass transfer and diffusion rate between the phases conversion from sol to gel, causes high homogeneous supersaturation which induces rapid nucleation to produce smaller colloids [6]. Fig.…”

Study of Formulation Variables Influencing Polymeric Microparticles by Experimental Design

“…Many microencapsulation processes are modifications of the three basic techniques: solvent extraction/evaporation, phase separation (coacervation), and spray-drying techniques [9]. Solvent evaporation and organic phase separation techniques are widely used in the pharmaceutical industry for the preparation of microparticles [1,2,[9][10][11][12]. These microparticles can reduce side effects, enhance the efficacy of therapy, and increase patient compliance.…”