bioactive molecules ONLY active via microinjection?

[Kate Michie]

 I am doing some experiments testing various drug delivery methods and I
want to know if anyone knows of any smallish molecules that are bioactive
BUT cannot diffuse across plasma membranes.(eg. molecules that must be
mircoinjected) to be used as a cargo? Thanks for any suggestions .

KATE.
Katharine Michie
Department of Biochemistry
University of Sydney
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