Silyl ether groups, typically used to protect alcohol functions in organic synthesis, offer good control over the rate and mechanism of their cleavage through judicious choice of silicon substituents. Now, Joseph DeSimone and co-workers from the University of North Carolina have used this tunable stability to prepare acid-sensitive materials that show promise for medical devices (J. Am. Chem. Soc. 132, 17928–17932; 2010).
Four bifunctional silyl ethers (CO–Si(R)2–OC, where R is a methyl, ethyl, isopropyl or tert-butyl group) bearing a terminal acrylate moiety on each side chain were crosslinked and subsequently moulded into particles with well-defined morphologies. The particles degraded in acidic conditions — known to exist in 'unhealthy' tissue — and the rate of degradation could be influenced significantly by using different alkyl substituents; bulkier groups slow the rate of degradation. DeSimone and co-workers used this concept to control the rate of release of the drug Rhodamine B from cubic microparticles. They also visualised in vitro degradation with transmission electron and laser scanning confocal microscopies using 'hexnut'-shaped nanoparticles (pictured), which were easily recognizable in cellular environments.
The original version of this story first appeared on the Research Highlights section of the Nature Chemistry website.
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Pichon, A. Silyl ether linkers. Nature Chem 3, 97 (2011). https://doi.org/10.1038/nchem.979
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DOI: https://doi.org/10.1038/nchem.979