# US 4,400,391 A · Controlled release of bioactive materials using alginate gel beads

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- Number: US 4,400,391 A
- Document ID: US4400391A
- Status: Granted
- Kind: A
- Application number: 06/212,655
- Filed: 1980-12-03
- Granted: 1983-08-23
- Earliest claimed: 1980-01-09
- Assignees: The United States of America as represented by the Secretary of Agriculture
- Inventors: William J. Connick, Jr.
- Web page: https://patentgrep.com/patent/US4400391A

## CPC

- A01N 25/10: Macromolecular compounds
- A61K 9/1652: {Polysaccharides, e.g. alginate, cellulose derivatives; Cyclodextrin (homeopathic globules A61K9/1623)}
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)

## Abstract

Alginate gel beads containing bioactive materials dispersed therein are the product and the process of this invention. These beads can be made to either float or sink in aqueous environments, and are capable of providing the controlled release of their bioactive materials when applied to terrestrial or aqueous environments.

## Claims

### Claim 1

A process for preparing alginate gel beads containing insecticide materials consisting essentially of:
(a) mixing an effective quantity of alginate for gelation with an effective quantity of 1-a-cyano-c-phenoxybenzyl d, cis-dibromochrysanthemate, for incorporation into a final gel bead, in water;
(b) placing the mixture in a vessel equipped to dispense liquids dropwise;
(c) mixing an effective quantity of water-soluble metal salt or acid which can gel alginates, with an effective quantity of water to obtain a solution;
(d) adding, dropwise, the alginate mixture of (b) into the solution of (c); thus forming gel beads, which contain the insecticide material dispersed uniformly therein, allowing the beads to remain in contact with the solution of (c) for an effective period of time necessary to allow gelation, and
(e) separating the gelled beads from the solution of (c).

### Claim 2 (depends on 1)

The process of claim 1 wherein the metal salt is a divalent metal salt.

### Claim 3 (depends on 2)

The process of claim 2 wherein the divalent metal salt is a barium salt.

### Claim 4 (depends on 3)

The process of claim 3 wherein the barium salt is barium chloride.