Microencapsulation using vibrating technology.

For over a half a century now, microencapsulation has played a very important role in many industries and in the recent decades, this versatile technology has been applied to numerous biotechnology and medical processes. However, successful application in these areas requires a methodology which has the capability to produce mono-dispersed, homogenous-shaped capsules, with a narrow size distribution, using a short production time. The manufacture of capsules using vibrating technology has gained significant interest mainly due to its simplistic approach to produce homogenous microcapsules with the desired characteristics for biotechnological and medical processes. However, certain limitations still exist for this methodology, which include the inability to manufacture microcapsules at large quantities and/or using highly viscous polymers. In this review, a detailed description of the theoretical and practical aspects behind the production of different types of alginate-based microcapsules, for application in biotechnological and medical processes, using vibrating technology, is given.

Capsular perstraction as a novel methodology for the recovery and purification of geldanamycin.

The molecular complex "Heat shock protein 90" has become a novel target for anticancer drugs in recent times on account of its ability to perform as a chaperone toward proteins involved in cancer progression. The geldanamycin binds to this complex with high affinity and prevents it from performing correctly, which results in tumor destruction. The aim of this study was to investigate the feasibility of applying liquid-core microcapsules as a novel technique (termed "capsular perstraction"), for the recovery and purification of geldanamycin from culture media. Results demonstrated how this procedure was capable of rapidly extracting >70% of geldanamycin from culture media using a liquid-core volume to medium ratio of only 1%. Optimum conditions for removal, including agitation speed, microcapsule size, and membrane thickness were examined, and it was shown how the stagnant aqueous film around the microcapsules was the main resistance to mass transfer. A volumetric mass transfer coefficient of 5.66×10(-6) m/s was obtained for the highest agitation speed (400 rpm), which was considerable greater compared to the value of 0.88×10(-6) m/s achieved for the lowest speed of 100 rpm. Removal of geldanamycin from microcapsules was also examined to fully investigate the potential of such particles for in situ product recovery, and it was demonstrated how the methodology can be used as a simple mechanism for purifying the compound (>99%) through solvent extraction and crystallization. The results of this work demonstrate the novel use of capsular perstraction as a methodology for the recovery and purification of geldanamycin from culture environments.

Removal of pharmaceuticals from water: using liquid-core microcapsules as a novel approach.

In recent years ever-increasing amounts of pharmaceuticals are being detected in the aquatic environment and in some cases, they have even been discovered in drinking water. Their presence is attributed mainly to the inability of sewage treatment plants to adequately remove these compounds from the sewage influent. The aim of this study was to investigate the feasibility, kinetics and efficiency of using liquid-core microcapsules as a novel methodology, termed capsular perstraction, to remove seven pharmaceuticals commonly found in the environment, from water. The process involves the envelopment of pre-selected organic solvents within a porous hydrogel membrane to form liquid-core microcapsules, which can be used to extract a large range of compounds. Results indicate that this novel approach is capable of extracting the seven chosen compounds rapidly and with a variable efficiency. The simultaneous use of both dibutyl sebacate and oleic acid liquid-core microcapsules at a liquid volume ratio of only 4% (v/v) resulted in the following extractions within 50min of capsule addition to contaminated water: furosemide 15%; clofibric acid 19%; sulfamethoxazole 22%; carbamazepine 54%; warfarin 80%; metoprolol 90% and diclofenac 100%. The effects of different agitation rates, microcapsule size and membrane thickness on the rate of mass transfer of warfarin into the liquid-core (dibutyl sebacate) of microcapsules was also examined. Results showed that the main rate-limiting step to mass transfer was due to the stagnant organic film (microcapsule size) within the core of the microcapsules. A volumetric mass transfer coefficient of 2.28x10(-6)m/s was obtained for the smallest microcapsules, which was nearly 4-fold higher compared to the value (0.6x10(-6)m/s) obtained for the largest microcapsules used in this study. Even with this resistance liquid-core microcapsules are still capable of the rapid extraction of the tested compounds and may provide a platform for the safe disposal of the pharmaceuticals after removal.