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Silk fibroin (SF) offers great opportunities in manufacturing biocompatible/partially biodegradable devices with environmental benignity and biomedical applications. To obtain active SF devices of next generation, this work is to demonstrate a new functionalization strategy of the mesoscopic functionalization for soft materials. Unlike the atomic functionalization of solid materials, the meso-functionalization is to incorporate meso-dopants, i.e., functional molecules or nanomaterials, quantum dots, into the mesoscopic networks of soft materials. In this work, wool keratin (WK) molecules were adopted as mediating molecules to incorporate gold nanoclusters (AuNCs), into the mesoscopic networks of SF. It follows from our analyses that the β-crystallites between WK and SF molecules establish the binding between WK@AuNCs and the SF networks. The incorporated WK@AuNCs are electron rich and serve as electronically charged nano particles to bridge the growth of Ag filaments in bio-degradable WK@AuNCs-SF memristors. The meso-functionalization can greatly enhance the performance of SF materials and endows them with new functionalities. This can be highlighted by biocompatible/partly degradable WK@AuNCs functionalized SF resistive random-access memories, having the enhanced resistive switching memory performance, and the unique synapse characteristics and the capability of synapse learning compared with neat SF devices, and of great importance in nonvolatile memory, analog circuits, and neuromorphic applications.

To fabricate biocompatible composite films with tunable performance, both silk fibroin (SF, β-crystallite rich) and keratin (α-helix rich) materials are engineered at the mesoscale based on the molecular synergy. While SF materials display a hierarchical structure initiated from the β-crystallite molecular networks, keratin materials reveal the networks crossly linked by disulfide bonding. It is surprising to see that the β-crystallites of SF materials induce the conversion of the free unfolded molecular chains of keratin to β-folding (β-crystallites) in the SF/keratin composites. Furthermore, the α-helices from the keratin components in the SF/keratin composites can transit to β-sheets under stress, which gives rise to the strain-hardening, and a better flexibility and elasticity. It follows that the tensile and biodegradable performance of the SF/keratin composites can be programmed by adjusting the ratio of SF versus keratin in the composites. Raising the SF ratio in the composite films increases the density of β-crystallites in the networks, giving rise to the enhanced toughness and reduced biodegradation rate, but poor deformation recovery. On the other hand, increasing the ratio of keratin in the composite films increases the extensibility, strain-hardening effect. These make them excel bio-optical materials with controllable properties. macroscopic performance. Wool keratins are composed of the intermediate filament proteins and the matrix proteins. Intermediate filament proteins have an average molecular mass of 40-60 kDa while the matrix proteins are of 11-26 kDa. [15] Wool fibers are mainly composed of keratin intermediate filaments, which are organized as coiled coils with a diameter of 7 nm due to their hierarchical structures ( Figure 1B): each dimer (45 nm long) is formed by two individual right-handed α-helix chains to constitute protofibrils with disulfide bonds. [16] The dimers aggregate then into protofilaments (about 2 nm in diameter) end-to-end and side-by-side. These form protofibrils which eventually combine into helical intermediate filaments of wool fibers. [6] For the above structure, the disulfide cross-links are of great importance for stabilizing the multilevels of wool fibers. Consequently, the route of introducing the networks of keratins will promote the formation of disulfide bonds at heating. [17] According to the latest studies, [1] the performance of soft materials are directly correlated with the five structural factors of mesoscopic structures: (1) the topology of networks, (2) the correlation length among building units, (3) the orientation and (4) the interactions of structural units, and (5) the hierarchy of mesoscopic structure. [1] Based on this principle, the function and macroscopic performance of soft materials can be modified by the following two paths: [1,12,18] Path (1) is to modify the mesoscopic structure so as to acquire desired performance. This requires the knowledge on the correlation between the mesoscopic structure of soft materials and the performance, and ...

The prevalence of perceptions of odors and sensations of air humidity and sick building syndrome symptoms in domestic environments were studied using responses to a questionnaire on the home environment. Parents of 4530 1–8 year old children from randomly selected kindergartens in Chongqing, China participated. Stuffy odor, unpleasant odor, pungent odor, mold odor, tobacco smoke odor, humid air and dry air in the last three month (weekly or sometimes) was reported by 31.4%, 26.5%, 16.1%, 10.6%, 33.0%, 32.1% and 37.2% of the parents, respectively. The prevalence of parents’ SBS symptoms (weekly or sometimes) were: 78.7% for general symptoms, 74.3% for mucosal symptoms and 47.5% for skin symptoms. Multi-nominal regression analyses for associations between odors/sensations of air humidity and SBS symptoms showed that the odds ratio for “weekly” SBS symptoms were consistently higher than for “sometimes” SBS symptoms. Living near a main road or highway, redecoration, and new furniture were risk factors for perceptions of odors and sensations of humid air and dry air. Dampness related problems (mold spots, damp stains, water damage and condensation) were all risk factors for perceptions of odors and sensations of humid air and dry air, as was the presence of cockroaches, rats, and mosquitoes/flies, use of mosquito-repellent incense and incense. Protective factors included cleaning the child’s bedroom every day and frequently exposing bedding to sunshine. In conclusion, adults’ perceptions of odors and sensations of humid air and dry air are related to factors of the home environment and SBS symptoms are related to odor perceptions.

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