Monodisperse, polymeric microspheres produced by irradiation of slowly thawing frozen drops
US4981625A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1988 |
| Grant date | Jan 1, 1991 |
| Priority date | — |
| Expiry date | Mar 14, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/2982
- WIPO fieldPharmaceuticals
- WIPO sectorChemistry
Abstract
Monodisperse, polymeric microspheres are formed by injecting uniformly shaped droplets of radiation polymerizable monomers, preferably a biocompatible monomer, having covalent binding sites such as hydroxyethylmethacrylate, into a zone, impressing a like charge on the droplet so that they mutually repel each other, spheroidizing the droplets within the zone and collecting the droplets in a pool of cryogenic liquid. As the droplets enter the liquid, they freeze into solid, glassy microspheres, which vaporizes a portion of the cryogenic liquid to form a layer. The like-charged microspheres, suspended within the layer, move to the edge of the vessel holding the pool, are discharged, fall and are collected. The collected microspheres are irradiated while frozen in the cryogenic liquid to form latent free radicals. The frozen microspheres are then slowly thawed to activate the free radicals which polymerize the monomer to form evenly-sized, evenly-shaped, monodisperse polymeric microspheres.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.