Optically Triggered Release of DNA from Multivalent Dendrons by Degrading and Charge-Switching Multivalency

摘要

Multivalent binding between nanoscale objects has recently emerged as one of the most powerful methods for the assembly of functional supramolecular materials with applications in nanotechnology. Controlling the self-assembly of nanomaterials by using external stimuli, such as pH, temperature, light, electric potential, or magnetic field, is an important requirement for the preparation of functional and responsive materials for a wide range of potential applications. Stimuli-responsive materials have been extensively pursued, with special focus on medicinal applications; for example, controlled drug and DNA delivery systems, reactivation of caged enzymes, and switchable membrane proteins. The use of light as an external stimulus offers a number of advantages, because light is easy to apply, relatively harmless to living organisms, and-importantly- controllable both spatially and temporally. DNA-binding compounds that can be manipulated by light are especially interesting in nonviral gene therapy, which relies on synthetic compounds that protect, transport, and release DNA into target cells. Cationic dendritic systems have been of particular interest in this regard. Pioneering gene-therapy research has been conducted with polyamidoamine (PAMAM) dendrimers, while dendritic poly(L-lysine) and poly(propylene imine) have also been studied. Many of these compounds bind DNA. However, unpacking of the complexes and release of the DNA is difficult to achieve if the binding is very strong, which results in a low transfection efficiency. DNA release is therefore of direct importance.