Preparation of polyacrylamide based microgels with different charges for drug encapsulation

• Published in: European polymer journal Vol. 49; no. 6; pp. 1479 - 1486
• Main Authors: Wang, Hui, Helwa, Youssef, Rempel, Garry L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2013; Elsevier
• Subjects: Applied sciences; Biological and medical sciences; Cationic; Drug delivery systems; Drug encapsulation; Drugs; Encapsulation; Exact sciences and technology; Fluorescein; General pharmacology; Hydrogels; Medical sciences; Organic polymers; Particle size; pH responsive; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Physicochemistry of polymers; Properties and characterization; Solution and gel properties; Stores; Drug encapsulation; Particle size; Hydrogels; pH responsive; Fluorescein; Ionomer; Emulsion copolymerization; Control release polymer; Drug carrier; Experimental study; Acrylamide derivative polymer; Sulfonate copolymer; Structure processing relationship; Particle size distribution; Acrylamide copolymer; pH; Acrylamide polymer; Microgel; Allylic derivative copolymer; Microencapsulation; Polydispersed particle; Radical copolymerization; Amine copolymer
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2013.04.003

Z-stack confocal images of fluorescein encapsulated cationic hydrogels at pH=13. The series of images (left) are the same set of hydrogels at different heights. These images were taken using a 488nm laser. The right image was taken from the middle of the hydrogels microparticles. Scale bar=10μm. The confocal fluorescence microscopy images provide strong evidence that the drug was encapsulated into the hydrogel particles and molecularly dispersed within the cationic and anionic hydrogels at pH=13. An encapsulation efficiency of ∼45wt% was obtained under these two conditions. The prepared hydrogels show a potential in the applications of drug storage and delivery. [Display omitted] •Nine types of hydrogels with different charge at different pH were prepared.•Fluorescein was used to assess and optimize the encapsulation efficiency.•The charges and pH of hydrogels are important on the fluorescein encapsulation.•Maximum drug loading was reached for anionic and cationic hydrogels at pH=13. The unique physicochemical properties of hydrogels have attracted considerable attention in their drug storage and delivery applications. Herein, a series of acrylamide based hydrogels with different charges (cationic, neutral, and anionic) under different pH (1, 7, and 13) were prepared via an inverse emulsion polymerization process. The effects of pH and aqueous to organic phase (w/o) ratio on the size of the produced hydrogels were studied. Fluorescein was used as the model drug to assess and optimize the encapsulation efficiency of the hydrogels. Optical microscopy and confocal fluorescence microscopy were carried out to examine the existence and distribution of fluorescein inside the hydrogels. It was found that the hydrogels were swollen to the greatest extent at pH=13 and their size increased with decreasing w/o ratio. Fluorescein was molecularly dispersed within the cationic and anionic hydrogels at pH=13 with an encapsulation efficiency of ∼45wt%. This study provides a convenient method to prepare hydrogels with the required properties and demonstrates the potential of using hydrogels to store and stabilize therapeutics.