Novel Alginate-Poly(L-histidine) Microcapsules as Drug Carriers: In Vitro Protein Release and Short Term Stability

• Published in: Macromolecular bioscience Vol. 5; no. 5; pp. 408 - 414
• Main Authors: Wang, Shi-Bin, Xu, Fei-Hai, He, Hong-Shan, Weng, Lian-Jin
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 23.05.2005; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: alginate; Alginates; Applied sciences; Biological and medical sciences; Capsules; Drug Carriers; Drug Delivery Systems; Drug Stability; Exact sciences and technology; General pharmacology; Glucuronic Acid; Hexuronic Acids; Histidine; Medical sciences; microencapsulation; Natural polymers; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Physicochemistry of polymers; poly(L-histidine); Proteins - administration & dosage; Proteins - pharmacokinetics; stability; Starch and polysaccharides; Time Factors; Control release polymer; Microcapsule; Drug carrier; Alginates; Experimental study; Property processing relationship; Histidine polymer; In vitro; Aminoacid polymer; Polyelectrolyte; Hemoglobin; Oside polymer; Monodispersed particle; Interpolymer; Microencapsulation; Kinetics; Release; Growth from solution
• ISSN: 1616-5187; 1616-5195
• DOI: 10.1002/mabi.200400204

Spherical, smooth‐surfaced and mechanically stable alginate‐poly(L‐histidine) (PLHis) microcapsules with narrow particle size distributions were prepared by incubating calcium alginate beads in aqueous solutions of PLHis. The in vitro release characteristics, drug loading and encapsulation efficiency of the microcapsules were investigated using bovine erythrocytes hemoglobin (Hb) as a model drug. The results showed that the concentration of Ca2+ ions had a considerable effect on the drug loading, encapsulation efficiency and in vitro release behavior of the microcapsules. When the concentration of CaCl2 in the PLHis solution was increased from 0 to 3.0% (w/v), the drug loading and encapsulation efficiency decreased significantly from 38.0 to 4.3% and from 92.9 to 8.0%, respectively, while the total cumulative release of Hb from microcapsules in phosphate buffered saline solution (PBS, pH 6.8) decreased from 96.2 to 72.8% in 24 h. No significant protein release was observed during 70 h of incubation in hydrochloric acid solution (pH 1.2). However, under neutral conditions (PBS, pH 6.8), the Hb was completely and stably released within 24–70 h. An explosion test showed that the stability of alginate‐PLHis microcapsules depended strongly on the concentration of PLHis and the calcium ions in solution. Microscopy photo of Hb‐loaded alginate‐PLHis microcapsules.