Synthesis and characterisation of aqueous haemoglobin-based microcapsules coated by genipin-cross-linked albumin

Abstract

Figure 1. After co-precipitation of MnCO3 and Hb, BSA forms an additional layer around the MnCO3/Hb-particle. BSA within this layer is then cross-linked by addition of genipin and later the MnCO3 in the core of the particle is dissolved by EDTA, resulting in a stable shell of BSA around the Hb-core. The mechanism of cross-linkage by genipin has been described by Butler et al. in 2003. R represents the amino-sidechains of BSA. Bovine serum albumin (BSA)-coated haemoglobin (Hb)-microcapsules prepared by co-precipitation of Hb and MnCO3 may present an alternative type of artificial blood substitute. Prepared microcapsules were analysed by Scanning electron microscopy (SEM) and Respirometry, cytotoxicity was evaluated by addition of microcapsules to murine fibroblast-derived cell line L929 (American Type CultureCollection, NCTC clone 929 of strain L). The capsules come along with a mean diameter of approximately 0.6 μm and a mean volume of 1.13 • 10 -19 L, thus an average human red blood cell with a volume of 9 • 10 -14 L is about 800,000 times bigger. Hb-microcapsules are fully regenerable by ascorbic acid and maintain oxygen affinity because oxygen is able to pass the BSA wall of the capsules and thereby binding to the ferrous iron of the haemoglobin entity. Therefore, these microcapsules present a suitable type of potential artificial haemoglobin-based oxygen carrier (HbOC).