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Hydrogels mimic the natural extracellular matrix in terms of their nanofibrous structure and large water content. However, the lack of a combination of properties including sufficient heterogeneity in the gel structure, intrinsic antimicrobial activity, and bioactivity limits the efficiency of hydrogels for tissue engineering applications. In this work, a hydrogel with a combination of these properties was fabricated by hybridizing silk fibroin with a low-molecular-weight peptide gelator. It was observed that silk fibroin and the peptide gelator assembled orthogonally in sequence. While the morphology of silk fibroin nanofibrils was not affected by the peptide gelator, silk fibroin promoted the formation of wider nanoribbons of the peptide gelator by modulating its nucleation and growth. Orthogonal assembly maintained the antimicrobial activity of the peptide gelator and the excellent biocompatibility of silk fibroin in the hybrid gel. The hybrid gel also demonstrated improved interactions with cells, an indicator of a higher bioactivity, possibly due to the heterogeneous double network structure.

Functionalization of silk fibroin hydrogel with antimicrobial activity is essential for promoting the applications of this excellent biomaterial. In this work, a simple approach based on electrostatic interaction is adopted to produce antimicrobial silk hydrogel containing an antimicrobial peptide (AMP), polymyxin B, an important last-line antibiotic to treat multidrug-resistant bacterial superbugs. The polycationic property of this peptide and the negative charge of silk fibroin lead to strong interactions between them, as demonstrated by changes in nanofibril structure, gelation kinetics, ζ-potential, fluorescence emission, and rheological properties of the gel. The hydrogels loaded with polymyxin B demonstrated antimicrobial activity against two Gram-negative bacterial strains. A combination of the results from the different characterizations suggests that the optimal molar ratio of polymyxin B to silk fibroin is 1:2.5. As most AMPs are cationic, this electrostatic approach is suitable for the straightforward functionalization of inert silk hydrogel with other AMPs.

CuO/MnO2 core/shell nanostructures were synthesized and successfully loaded on nylon fabric through one step chemical method. Copper oxide (CuO) is a low-cost and stable semiconductor and has promising applications in wearable devices or smart textiles. However, divalent nature of copper atoms makes it difficult to assemble on most synthetic fibers and usually display a poor distribution on fiber surface. This was addressed through using manganese as a transition metal to create complex with copper ions. Subsequently, a core/shell structure was obtained since copper ions had lower reduction potential than manganese ions. Thus, the preformed CuO nanoflowers (core) were uniformly covered by many small coarse MnO2 particles (shell). The created core/shell structure endows synergistic mechanical, self-cleaning and antibacterial properties on the fabric and more importantly, significantly improved the affinity and the distribution of CuO nanoflowers on the nylon fabric. The synthesized particles and treated fabrics were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, dispersive X-ray spectroscopy (EDX), X-ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR).