We report here a graft polymerization method to improve the cell adhesion property of Bombyx mori silk fibroin films. B. mori silk has evolved as a promising material for tissue engineering because of its biocompatibility and biodegradability. However, silk's hydrophobic character makes cell adhesion and proliferation difficult. Also, the lack of sufficient reactive amino acid residues makes biofunctionalization via chemical modification challenging. Our study describes a simple method that provides increased chemical handles for tuning of the surface chemistry of regenerated silk films (SFs), thus allowing manipulation of their bioactivity. By grafting pAAc and pHEMA via plasma etching, we have increased carboxylic acid and hydroxyl groups on silk, respectively. These modifications allowed us to tune the hydrophilicity of SFs and provide functional groups for bioconjugation. Our strategy also allowed us to develop silk-based surface coatings, where spatial control over cell adhesion can be achieved. This control over cell adhesion in a particular region of the SFs is difficult to obtain via existing methods of modifying the silk fibroin instead of the SF surface. Thus, our strategy will be a valuable addition to the toolkit of biofunctionalization for enhancing SFs' tissue engineering applications.

Research on tissue engineering has been actuated for want of improved treatments and has now come out as a likely alternative to organ transplantation. The two indispensable components for regeneration of tissues are cells and scaffolds. Stem cells are undifferentiated cells that have proliferative capacity and the ability to differentiate into specific mature lineages, which is called plasticity. The physical and chemical signals from the surrounding microenvironment can influence the proliferation as well as the differentiation of stem cells into more specialized cell types and thus play an important role regulating the fate of the stem cells. Over decades, scientists have revealed that the stem cells' growth and differentiation can be stimulated and regulated by scaffold properties. Silk fibroin has been used in both in vitro and in vivo tissue engineering applications and has shown promising results, particularly for bone tissue engineering applications. For successful application of stem cells in tissue engineering, directed differentiation of stem cells will have to include approaches that not only regulate cell-fate specification but also cell maturation to access a complete range of cell types and stages. One of the ways of achieving this is by modifying the surface properties of the scaffold to have control over the stem cell behavior and final product. In this spotlight on application, we recapitulate the current developments of silk-based materials and their surface modifications for patterning of cells and stem cell differentiation with a focus on bone tissue engineering.

Polydiacetylenes have attracted significant interest for their unique chromatic properties and applications in sensing, imaging, and optics. Here, it is demonstrated that aminoanthraquinone‐substituted diacetylenes exhibit distinct aggregation‐dependent chromatic properties, affected by the alignment of both the aminoanthraquinone headgroups and diacetylene sidechains. Specifically, it is shown that aminoanthraquinone‐diacetylene monomers adopt different film organizations depending upon the polarity of the solvent employed for predissolution. In particular, a yellow aminoanthraquinone‐diacetylene phase, which undergoes photopolymerization upon ultraviolet irradiation, is produced upon dissolution in polar organic solvents prior to deposition and drying on solid substrates. In contrast, a red phase that can not be polymerized is observed when the monomers are predissolved in apolar solvents. Microscopic and spectroscopic analyses indicate that the optical properties of the films are determined by the degree of overlap between the aminoanthraquinone headgroups as well as the alignment of the diacetylene sidechains; both factors are intimately affected by interactions of the monomers with solvent molecules. It is shown that the aggregation‐dependent diacetylene films exhibit remarkable solvochromic, thermochromic, and mechanochromic properties. The aminoanthraquinone‐substituted diacetylenes may facilitate chromatic tuning of polydiacetylene systems in the solid state, determined by solvent‐ and intermolecular interactions and concomitant self‐assembly of the pendant sidechains and aromatic headgroups.

Silk produced from Bombyx mori as a natural polymer has gained tremendous attraction for biomedical applications. Tissue engineering applications require meticulous spatial control over cellular adhesion, which is conventionally acquired via lithographic techniques. Here, we report formation of structures using nanogels that are readily cross-linked in the presence of photoactive groups that form stable, biocompatible patterned system for cellular growth. This direct approach has the proficiency to commission structures with reduced processing steps for obtaining biocompatible surface favoring stem cell adhesion, differentiation, and subsequent coculture with an additional cell type in a spatially controlled manner.