Capsule mechanical stability

Step 4 Capsule Mechanical Stability. The mechanical stability of the membranes was assessed semi-quantitatively by applying a compressional force via a micrometer. While this method is not precise, it did permit us to assess if the capsules could withstand deformations and if they ruptured in a controlled or catastrophic manner. Another test which was selectively employed was to place capsules between microscope slides and measure the force required to compromise the integrity of the membrane. These tests measured the resistance of the weakest point of the membrane. For certain capsules a needle was used to probe the breaking strength of a local region of the membrane. 

Our screening and testing of multicomponent capsules/beads is incomplete. However, it offers a novel approach for the material selection for immobilization devices, which permits the simultaneous control of permeability, mechanical stability, and compatibility. The alternative multicomponent systems presented herein offer new possibilities for biomaterials, particularly those employed in bio artificial organs. 

Daly, M.M. and Knorr, D. (1988) Chitosan-alginate complex coacervate capsules effects of calcium chloride, plasticizers, and polyelectrolytes on mechanical stability. Biotechnology Progress, 4,76—81. 

Multi-enzymatic catalysts are recognized as the future generation of biocatalysts. They were particularly designed as enzymes encapsulated into hybrid capsules [129]. It has already been proved that the multi-enzymes organization in a single capsule with separated space enhanced the catalytic capacity of the system. Such an example is the dual biocatalyst of formaldehyde and formate dehydrogenases encapsulated in the capsule lumen/wall. It catalyzed the cascade transformation of CO into formaldehyde [132]. Enzymes co-immobilization in separated spaces of the same cavity exhibited higher formaldehyde yields compared to the free enzyme. Also, the recyclability of the biocatalytic system confirmed the superior mechanical stability [132]. 

A related system is that of the lipid-bilayer corked capsule membranes which are formed from ultrathin (about 1 pm thick), spongy, 2.0- to 2.5-mm-diameter, more-or-less spherical nylon bags in which multiple bilayers are immobilized (Fig. 43) [343-345]. They were considered to combine the advantages of mechanical and chemical stabilities of polymeric membranes with the controllable permeabilities of surfactant vesicles. Polymerization of the bilayers, in situ,... 

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