Regulation of the gelatin helix-to-coil transition through chain confinements at the polymer-protein interface and protein-protein interface

Abstract

Gelatin is an essential material widely used in biomedical applications due to its characteristic temperature responsivity—helix-to-coil transition. However, the current helix-to-coil transition is limited by its single-step behavior and the difficulty in designing a specific onset temperature. In this study, we investigated the fundamentals of the helix-to-coil transition with a focus on gelatin chain mobility. We observed distinctive kinetics of the helix-to-coil transition, which is resilient and can actuate in multiple steps or with a controllable onset point. This was achieved by confining the gelatin chain with a hydrophilic polymer or gelatin itself. The confinement approach serves two purposes: first, it prevents excessive mobility of the generated coils, maintaining physical resilience after the helix-to-coil transition; second, the interfacial confinement between the polymer and gelatin, referred to as polymer-protein interface confinement, restricts the helix-to-coil transition, resulting in a multistep transition process. Additionally, strong confinement at the interface between gelatins of different origins, that is protein-protein interface confinement, shifts the onset temperature to a higher point. This fundamental comprehension of helix-to-coil transition could contribute to broadening the biomedical application potential of gelatin materials.

Statement of significance

Gelatin is essential in biomedical applications due to its characteristic temperature responsivity—helix-to-coil transition. Herein, we fundamentally investigated the distinctive kinetics of the helix-to-coil transition, which is resilient and can actuate in multiple steps or with a controllable onset point. This was achieved by confining the gelatin chain with a hydrophilic polymer or gelatin itself. The gelatin chain confinement prevents excessive mobility of the generated coils, maintaining physical resilience after the helix-to-coil transition. The interfacial confinement between the polymer and gelatin restricts the helix-to-coil transition, resulting in a multistep transition process. Additionally, strong confinement at the interface between gelatins of different origins shifts the onset temperature to a higher point.