In-vitro cytotoxic activity of cross-linked protein microcapsules

Microcapsules (5-100 microns) were prepared through interfacial cross-linking of various proteins (human serum albumin, lysozyme, haemoglobin, casein, pepsin) with glutaraldehyde or terephthaloylchloride. Surprisingly they all showed an inhibitory effect on cultured cells in a concentration range of 100 micrograms ml-1 to 10 mg ml-1. This effect seemed non-specific, reversible and to depend on contact with the cell plasma membrane. The electric charges of microcapsules could be involved in the inhibition phenomenon.