Southwest Research Institute 2001 Annual Report, Microencapsulation and Controlled Release

A pioneer in the field of microencapsulation, SwRI has expanded its facilities to provide cGMP (current Good Manufacturing Practices) services and increased capabilities in food and pharmaceutical research. Project areas include functional food, pharmaceuticals, consumer products, personal care, industrial chemicals, agriculture, and biotechnology. During 2001, the Institute's microencapsulation and controlled release contract research and development services received ISO 9002 certification.

The Institute participated in several client research and development programs for the microencapsulation of flavors and aromas. Recently, SwRI focused on the microencapsulation of flavor-enhancing aromas for shelf-life stability and for addition to packaging materials to enhance consumer appeal. This project led to the development of microcapsules that rupture as packages are handled, releasing a product-related aroma.

During the past two years, microencapsulation research of vitamins, minerals, and functional ingredients has exploded for a wide variety of food applications. Scientists have formulated food ingredients for masking undesirable tastes and odors and for protecting against oxidation, reactive species, moisture, and heat. SwRI engineers apply microencapsulation techniques, such as disk and coextrusion processes, that enable clients to include special-purpose ingredients in frozen food, soups, sauces, powdered drinks, and baking products.

SwRI recently used its centrifugal coextrusion process to prepare encapsulated nutraceuticals for premium pet foods. The encapsulated product provides significant stability for storage and pet food processing conditions. SwRI is working closely with the client to move the encapsulated nutraceuticals into cGMP production and will design scaled-up production processes in the coming months.

SwRI scientists are helping a client to develop alternative treatments for Parkinson's disease and alcohol addiction. For these research programs, SwRI is extruding potent morphine analogues in a nonbioresorbable implantable polymer. Solubilities or extrusion conditions are varied to release the drug from the implant at a constant rate over a three- to six-month period.

Institute researchers are working with an agrochemical company to encapsulate a new liquid fumigant. The new product is a promising replacement for an important fumigant that is being phased out for environmental reasons. The encapsulation will enable the company to conduct required toxicology studies at significant cost savings when compared to other available dose delivery methods.

Using SwRI's spinning disk technology, pesticides are being encapsulated for roach baits. Encapsulation prolongs stability of the pesticide during storage and bait formulation and provides the added benefit of allowing the bait to be prepared in a factory rather than in the field at the time of application.

Microencapsulation of a mosquito larvicide for a pesticide manufacturer recently entered its sixth year. Capsules are produced using an interfacial polymerization process and are approximately 20 micrometers in size, which makes them suitable for spray applications on ponds and stagnant water. The larvicide, which has been used in the United States, contains the active ingredient methoprene to prevent mosquito larvae from maturing into adults. Methoprene is an insect growth regulator that does not harm fish, waterfowl, mammals, or other beneficial predatory insects.

Institute researchers co-developed, co-patented, and provided the design and fabrication expertise to scale up a novel encapsulation process from the laboratory to the pilot plant. This process reduces costs and improves the performance of a fluid transport aid. The existing process requires two steps: bulk polymerization and cryogenic grinding. The new process causes polymerization that results in small particles of the polymer product in a single step, and is proven in the laboratory.

SwRI is microencapsulating curing agents for adhesives for use in various applications. Curatives for adhesive systems have been encapsulated to provide thermal or pressure release in one-part formulations for automotive, aerospace, and other industrial applications.

Scientists encapsulated biocatalysts using the Institute's centrifugal coextrusion technology. The encapsulated catalysts were designed to provide prolonged activity in synthesis of a specialty chemical and to withstand the rigorous conditions of the synthesis for multiple cycles. The product proved effective and economical, and SwRI is working to build the encapsulation process to pilot-scale production capacities.

In an internal research and development agreement in conjunction with the federal Centers for Disease Control and Prevention in Atlanta, SwRI scientists are developing an oral vaccine for delivery of the rabies virus antigen that would provide sustained release in the Peyer's patches, located in the digestive tract. Successful development of this product would help prevent and control rabies in coyotes, dogs, raccoons, and other wildlife. A variety of biomaterials were used to design the microencapsulated formulations. These formulations are currently under in vivo evaluation.

Copyright© 2002 by Southwest Research Institute. All rights reserved under U.S. Copyright Law and International Conventions. No part of this publication may be reproduced in any form or by any means, electronic or mechanical, including photocopying, without permission in writing from the publisher. All inquiries should be addressed to Communications Department, Southwest Research Institute, P.O. Drawer 28510, San Antonio, Texas 78228-0510, phone (210) 522-2257, fax (210) 522-3547.