Abstract
Purpose. The influence of chemical parameters on the sensitivity to enzymatic degradation by α-amylase of starch microspheres cross-linked by epichlorohydrin was studied.
Methods. Starch microspheres were prepared using epichlorohydrin as a crosslinking agent. Their swelling degree, reflecting the number of glycerol diether bridges in the polymeric network, and the number of non-crosslinking monoglycerol ether groups corresponding to a side-reaction of epichlorohydrin with starch were determined. Degradation rates of the microspheres in presence of porcine α-amylase were determined by a microvolumetric method.
Results. Degradation by α-amylase was surface-controlled and could be modulated by the introduction in the polymeric network of: (i) non-hydrolysable α-1,6 bonds related to the presence of amylopectin in the raw starch, (ii) glycerol diether and, (iii) monoether groups, all of these being likely to block the activity of α-amylase. In the case of highly cross-linked microspheres, the number of glycerol monoether pendent chains had a predominant effect on the degradation rate which ranged between 10−2 and 10−5 min−1.
Conclusions. It was possible to modulate simultaneously the swelling degree and the enzymatic degradability of starch microspheres by adjusting the chemical parameters during the crosslinking reaction.
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Hamdi, G., Ponchel, G. Enzymatic Degradation of Epichlorohydrin Crosslinked Starch Microspheres by α-Amylase. Pharm Res 16, 867–875 (1999). https://doi.org/10.1023/A:1018878120100
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DOI: https://doi.org/10.1023/A:1018878120100