Hollow silica shells have been developed as molecular delivery vehicles, being able to ‘contain’ and deliver chemical actives for a wide range of commercial applications. This has particular relevance with respect to molecular delivery in biological systems, which may in-turn lead to usage of the shells in either the pharmaceutical or veterinary sectors.

Endocytosis of the shells into mammalian cells has been one area of investigation that has yielded some interesting results. For this the shells were loaded with a range of fluorescent dyes and also over-coated with poly-L-lysine.

The following images show (left) J774 machrophages containing internalised clusters of Rhodamine B containing silica shells (red) and stained for actin filaments (green), and (right) CaCO2 cells exposed to Rhodamine B containing silica shells (red) and stained for filamentous actin (green).

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Pictures courtesy of Dr Robin May, Birmingham University

Simple molecular delivery experiments have included loading the shells with a red-fluorescing fluorophore that contained a long alkyl chain to promote delivery into the lipid bilayer of the cell membrane. Three-dimensional reconstruction of a J774 cell five minutes after exposure to the loaded shells is shown below. The fluorophore (red) has interchelated into the plasma membrane of the cell, ‘outlining’ it. Delivery was both quick and cell autonomous, such that the fluorophore could be delivered to a single cell whilst leaving neighbouring cells (that had not bound to shells) untouched.

Picture courtesy of Dr Robin May, Birmingham University

Rhodamine B containing silica shells have also been fed to c. elegan nematode worms and their progress tracked through the gut.

Picture courtesy of Dr Robin May, Birmingham University

Please contact us if you would like to enquire more about the use of Hollow silica shells as molecular delivery vehicles in biological systems.