Switching the Biointerface of Displaceable Poly-p-xylylene Coatings.

A new class of functionalized poly-p-xylyene coating has been synthesized to provide switchable and displaceable surface properties for biomaterials. The switchability is achieved through a mechanism for detaching/attaching biomolecules and/or a mechanism through which the programmed restoration of functions or their replacement by other functions can be carried out. This advanced version of poly-p-xylylene comprises an integrated disulfide moiety within the functional side group, and the switching phenomenon between the immobilized functional molecules is triggered by the redox thiol-disulfide interchange reaction. These dynamically well-defined molecules on the surfaces respond simultaneously to altered biological properties and controlled biointerfacial functions, for example, switching wettability or reversibly altered cell adhesion activity. Poly-p-xylylenes are a key player in controlling surface properties for many important applications, such as medical implants, biosensors, bioMEMS devices, and microfluidics. The introduction of this new facet of poly-p-xylylenes enables the dynamic mimicry of biological functions relevant to the design of new biomaterials.