Protein Gradient Films of Fibroin and Gelatine

Abstract

Gradients are a natural design principle in biological systems that are used to diminish stress concentration where materials of differing mechanical properties connect. An interesting example of a natural gradient material is byssus, which anchors mussels to rocks and other hard substrata. Building upon previous work with synthetic polymers and inspired by byssal threads, protein gradient films are cast using glycerine-plasticized gelatine and fibroin exhibiting a highly reproducible and smooth mechanical gradient, which encompasses a large range of modulus from 160 to 550 MPa. The reproducible production of biocompatible gradient films represents a first step towards medical applications.

Bioinspired Mechanical Gradients in Cellulose Nanofibril/Polymer Nanopapers

“…[6] Theapproach was extended to gradient biopolymer gels and films based on fibroin and gelatin. [7] Ty pically,the mechanical properties are only described for selected positions of the gradient ex situ by cutting samples perpendicularly,orbyreplicating mixtures reminiscent of the composition of the gradient. However,t his does not give sufficient information on the real strain fields in situ, which needs to be understood for actual materials design.…”

Bioinspired Mechanical Gradients in Cellulose Nanofibril/Polymer Nanopapers

“…reported linear gradients composed of di‐ or trifunctional acrylates (as crosslinkers) and thio‐siloxane (as prepolymer) via the controlled mixing and lateral deposition using two syringes filled with prepolymer and crosslinker and by changing their mixing ratios during extrusion . The approach was extended to gradient biopolymer gels and films based on fibroin and gelatin …”

Dragline, Egg Stalk and Byssus: A Comparison of Outstanding Protein Fibers and Their Potential for Developing New Materials

“…Given the high binding affinity of the protein, it may also act as a linker that prevents slippage between softened fibrils, thus contributing to the strain‐induced stiffening of proximal byssus 97. Beyond such speculation, a matrix protein capable of adjusting the assembly and mechanics of collagen has a wealth of potential applications in biomaterials research such as in tuning the properties of collagen‐based gradient materials inspired by the mussel byssus 98…”

“…Taking the mechanical gradient of byssus as inspiration and building upon previous work with synthetic polymers, large centimeter scale gelatin/fibroin gradient films have been produced using a precision pump system 98. The films exhibit a fully reproducible range of modulus similar to that of their natural models (ca.…”