In recent years, production and characterization of anisotropic particles has become of interest in a wide range of scientific fields including polymer chemistry, drug delivery, electronics, energy, and nanotechnology. In this work, we demonstrate a novel formulation for production of anisotropic particles via an internal phase separation of biodegradable components. Specifically, binary mixtures of biodegradable polymers poly(lactic-co-glycolic acid), polycaprolactone, and biodegradable lipid Precirol (glyceryl palmitostearate) were dissolved in dichloromethane, emulsified, and prepared into anisotropic particles using a modified solvent evaporation technique. During the slow evaporation process the components self-assembled into anisotropic particles with distinct morphologies. Polymer/polymer formulations resulted in compartmentalized anisotropic heterodimer particles, while polymer/lipid combinations yielded "ice cream cone" shaped particles. It was found that addition of certain active pharmaceuticals resulted in an altered, pox-like segregation at the particle surface of polymer/polymer formulations. The anisotropic nature of the particles was subsequently characterized using optical microscopy, scanning electron microscopy, zeta potential, electrophoresis, and X-ray diffraction. Successful formulations presented here may potentially be employed as multicompartmental drug carriers with staggered drug release rates or alternatively as a colloidal excipient for an arsenal of pharmaceutical applications.

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In recent years, high-pressure homogenization has been used with increasing frequency to reduce the size of pharmaceutical suspensions to the micron, submicron, and nano scales with the goal of increasing the dissolution rate of the drug, and consequently, the in vivo bioavailability. As particle suspensions become smaller in size, increased concentrations of surfactants and stabilizers are required to prevent particle agglomeration. Recently, relatively high concentrations of biocompatible polymers have been used to stabilize suspensions by imparting surface-active steric stability as well as kinetic stability through an increase in suspension viscosity and/or a transition to non-Newtonian rheological properties. While the benefits of stable suspensions are known, little is known about the effect of the high polymer concentration on the actual breakup of the particles in suspension. In this work, designed experiments were used to identify the key parameters that govern the final particle size of a drug suspension following homogenization. In particular, drug loading, operating pressure, and polymer concentration were all found to be statistically significant factors in determining the resulting size of particles in suspension. In addition, it was found that an optimal polymer concentration of 2% (w/w) was required to adequately stabilize the particle suspension while simultaneously avoiding a decrease in homogenizer performance. Concentrations higher than 2% (w/w) resulted in size reduction limitations due to the increased viscosity (>10 cP) and the transition to nonNewtonian behavior.

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