The use of recombinant elastin-like materials, or elastin-like recombinamers (ELRs), in drug-delivery applications is reviewed in this work. Although ELRs were initially used in similar ways to other, more conventional kinds of polymeric carriers, their unique properties soon gave rise to systems of unparalleled functionality and efficiency, with the stimuli responsiveness of ELRs and their ability to self-assemble readily allowing the creation of advanced systems. However, their recombinant nature is likely the most important factor that has driven the current breakthrough properties of ELR-based delivery systems. Recombinant technology allows an unprecedented degree of complexity in macromolecular design and synthesis. In addition, recombinant materials easily incorporate any functional domain present in natural proteins. Therefore, ELR-based delivery systems can exhibit complex interactions with both their drug load and the tissues and cells towards which this load is directed. Selected examples, ranging from highly functional nanocarriers to macrodepots, will be presented.

Tissue engineering for cartilage repair requires biomaterials that show rapid gelation and adequate mechanical properties. Although the use of hydrogel is the most promising biomaterial, it often lacks in rigidity and anchorage of cells when they are surrounded by synovial fluid while they are subjected to heavy loads. We developed and produced the Silk Elastin-Like co-Recombinamer (SELR), which contains both the physical interaction from elastin motifs and from silk motifs. In the first part of this work, we set up and optimized a preannealing treatment based on the evolution of silk motifs into β-sheet structures in order to fulfill the required mechanical properties of hydrogels for cartilage repair. The new preannealed SELRs (pA(EIS) 2 -(I 5 R) 6 ) were characterized with the combination of several experimental techniques (CD, TEM, SEM, and rheology) to provide a deep insight into the material features. Finally, the regeneration properties of the pA(EIS) 2 -(I 5 R) 6 hydrogel embedded with chondrocytes were evaluated. After 4 weeks of culturing in a standardized and representative ex vivo model, the biochemical and histological analysis revealed the production of glycosaminglycans and collagen. Moreover, the immunohistochemistry showed the absence of fibro-cartilage and the presence of hyaline cartilage. Hence, we conclude that the pA(EIS) 2 -(I 5 R) 6 hydrogel presents improved mechanical properties while conserving the injectability, which leads to successful regeneration of hyaline cartilage in an ex vivo model.

The design and synthesis of nanostructured functional hybrid biomaterials are essential for the next generation of advanced diagnostics and the treatment of disease. A simple route to fabricate semiconductor nanofibers by self‐assembled, elastin‐like polymer (ELP)‐templated semiconductor nanoparticles is reported. Core–shell nanostructures of CdSe nanoparticles with a shell of ELPs are used as building blocks to fabricate functional one‐dimensional (1D) nanostructures. The CdSe particles are generated in situ within the ELP matrix at room temperature. The ELP controls the size and the size‐distribution of the CdSe nanoparticles in an aqueous medium and simultaneously directs the self‐assembly of core–shell building blocks into fibril architectures. It was found that the self‐assembly of core–shell building blocks into nanofibers is strongly dependent on the pH value of the medium. Results of cytotoxicity and antiproliferation of the CdSe‐ELP nanofibers demonstrate that the CdSe‐ELP does not exhibit any toxicity towards B14 cells. Moreover, these are found to be markedly capable of crossing the cell membrane of B14. In contrast, unmodified CdSe nanoparticles with ELPs cause a strong toxic response and reduction in the cell proliferation. This concept is valid for the fabrication of a variety of metallic and semiconductor 1D‐architectures. Therefore, it is believed that these could be used not only for biomedical purposes but for application in a wide range of advanced miniaturized devices.