|Claußen, K.U.; Lintz, E.; Giesa, R.; Schmidt, H.-W.; Scheibel, T.: Protein Gradient Films of Fibroin and Gelatine, Macromolecular Bioscience, 13(10), 1396-1403 (2013) -- DOI: 10.1002/mabi.201300221|
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. Producing large-scale gradients from biological materials, such as those found in mussel byssus, is difficult to realise in the laboratory. Building upon previous work with synthetic polymers and inspired by byssal threads, we have cast long protein gradient films using glycerine-plasticised gelatine and fibroin. These films exhibit a highly reproducible and smooth mechanical gradient which encompasses a large range of modulus from 160-550 MPa. The reproducible production of biocompatible gradient films represents a first step towards making higher-modulus materials for medical applications.