Southwest Research Institute 1995 Annual Report

For almost 50 years, SwRI has developed innovative microencapsulation products and processes for clients worldwide. Each year, the Institute conducts about 40 projects, primarily for industrial clients, in support of agriculture, medicine, nutrition, environmental protection, product safety, adhesives, and polymers. Research goals are to continually improve existing processes and to develop new ones to overcome the limitations of current technology.

The Institute is in the last year of a project for the Naval Air Warfare Center (NAWC) to develop a one-part epoxy adhesive that is stable at ambient conditions. A promising adhesive paste has been developed and tested by NAWC. The system will allow repairs to aluminum aircraft skin to be made under field conditions without refrigeration or mixing requirements. Development of a film adhesive using an encapsulated curative is almost complete.

The Institute has developed a centrifugal extrusion encapsulation process for a client in Nova Scotia, for the production of fish oil capsules for the human and animal health industries. The Institute is serving as technical consultant during plant construction and will also assist with plant start-up and worker training.

NASA's Lewis Research Center has developed an economical ion exchange resin that offers great potential for removing toxic heavy metal cations in contaminated waste water from sources such as city water treatment plants, industrial plants, and mining and electroplating operations. In support of this work, SwRI scientists are developing two delivery systems for the cation exchange material. One will produce particles in selected size increments over a 10 to 1,400 micrometer range for external treatment of waste water; the other will produce cation exchange microbeads (10 to 100 micrometers) with magnetic cores for in-line treatment.

As part of SwRI's biomaterials initiative program, engineers are developing biocompatible materials that can be used for pancreatic islet encapsulation for the treatment of type 1 diabetes. The capsule membranes allow diffusion of all essential nutrients necessary for viability of the islet cells, while blocking the transport of larger molecules, such as rejection-causing antibodies. SwRI is working with researchers at the Pittsburgh Transplantation Institute to harvest pancreatic islets, encapsulate them, and test the efficacy of the biomaterials in preclinical studies.

Institute scientists are studying the effects of vibration on capsule formation. The goal of this internal research program is to use vibrational disturbances to control the breakup of two-fluid jets, thereby reducing capsule size variance. At low vibration frequencies, large compound drops are formed, as are undesired satellite drops. As frequency is increased, both the main and satellite drops decrease in size. One of the goals is to determine whether a frequency range exists at which no satellites are present, and how this frequency range changes with fluid properties and processing conditions.

A dedicated Good Manufacturing Practices facility for conducting encapsulation studies related to the food and drug industry is now operational. Materials can be produced in quantities of up to 1,000 pounds. Standard operating procedures for the facility are in accordance with the Code of Federal Regulations 21, Part 211.

A patent has been granted to the Institute for a method of delivering microcapsules loaded with a mucosal immunization drug through the stomach to the Peyer's patch of immune cells in the small intestine, before the drug is absorbed. Targeted delivery and delayed absorption are strategies to prevent premature decomposition of drugs in the stomach.

Copyright© 1995 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.

Encapsulation Research