Versatile reversible cross-linking strategy to stabilize CCMV virus like particles for efficient siRNA delivery

Virus like particles obtained from the Cowpea Chlorotic Mottle Virus (CCMV) represent an innovative platform for drug delivery applications. Their unique reversible self-assembly properties as well as their suitability for both cargo loading and functionalization make them a versatile scaffold for numerous purposes. One of the main drawbacks of this platform is however its limited stability at physiological conditions. Herein, we report the development of a general reversible cross-linking strategy involving the homobifunctional cross-linker DTSSP (3,3'-dithiobis (sulfosuccinimidylpropionate)) which is suitable for particle stabilization. This methodology is adaptable to different CCMV variants in the presence or absence of a stabilizing cargo without varying neither particle shape nor size thus extending the potential use of these protein cages in nanomedical applications. Cross-linked particles are stable at neutral pH and 37 °C and they are capable of protecting loaded cargo against enzymatic digestion. Furthermore, the reversible nature of the cross-linking ensures particle disassembly when they are taken up by cells. This was demonstrated via the highly effective delivery of active siRNA into cells.