Spherulites: A new vesicular system with promising applications. An example: Enzyme microencapsulation

A new technology is tested for enzyme encapsulation. The capsules are small multilamellar vesicles of surfactant called spherulites which are produced by shearing a lamellar phase under well-controlled conditions. Encapsulati on of alkaline phosphatase into spherulites is studied here as an example. Once encapsulated, the enzyme is shown to be unable to develop any enzymati c activity on its substrate, the p-nitrophenylphosphate. This is due to the absence of contact between the enzyme and the substrate. Interestingly, th e whole enzymatic activity is recovered after destruction of the vesicles. Encapsulation efficiency ranges between 70% and 95% depending upon the enzy me over phospholipids ratio. Beyond the example of alkaline phosphatase, ma ny applications of spherulites in the medical or in the biotechnology field s seem now at hand. (C) 2000 American Institute of Physics. [S0021-9606(00) 70407-7].