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Dragline silk has been proposed to contain two main protein constituents, MaSp1 and MaSp2. However, the mechanical properties of synthetic spider silks spun from recombinant MaSp1 and MaSp2 proteins have yet to approach natural fibers, implying the natural spinning dope is missing critical factors. Here we report the discovery of novel molecular constituents within the spinning dope that are extruded into dragline silk. Protein studies of the liquid spinning dope from the major ampullate gland, coupled with the analysis of dragline silk fibers using mass spectrometry, demonstrate the presence of a new family of low-molecular-weight cysteine-rich proteins (CRPs) that colocalize with the MA fibroins. Expression of the CRP family members is linked to dragline silk production, specifically MaSp1 and MaSp2 mRNA synthesis. Biochemical data support that CRP molecules are secreted into the spinning dope and assembled into macromolecular complexes via disulfide bond linkages. Sequence analysis supports that CRP molecules share similarities to members that belong to the cystine slipknot superfamily, suggesting that these factors may have evolved to increase fiber toughness by serving as molecular hubs that dissipate large amounts of energy under stress. Collectively, our findings provide molecular details about the components of dragline silk, providing new insight that will advance materials development of synthetic spider silk for industrial applications.

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MIL-53(Fe), MIL-101(Cr), and MIL-53(Al) were successfully prepared to modify an electrode surface. With the differences in porous textural parameters and metal nodes, the physical characteristics and electrochemical performance toward chloramphenicol (CAP) detection at each modified electrode were systematically evaluated via CV and DPV measurements. Both MIL-53(Fe)/SPE and MIL-101(Cr)/SPE exhibited excellent electrochemical performances by enhancement of the EASA value, electro-catalysis, adsorption capacity, diffusion, and interaction with the CAP molecules. MIL-101(Cr)/SPE with a huge BET, large pore volume, and good redox electro-catalysis of Cr3+ metal nodes significantly enhanced electrochemical response, despite it was still limited by poor adsorption capacity and diffusion due to the strong water- interaction of the Cr3+ centers and steric effect of the cramped microporous system. MIL-53(Fe) with a much smaller specific surface area and pore volume showed good electrocatalysis of Fe3+, along with high interact ability and large adsorption capacity with CAP through hydrogen bonding and weak interaction with water. In contrast, MIL-53(Al)/SPE possessed poor electrochemical performance due to weak electron conductivity and the lack of electrocatalytic sites. Therefore, a perfect balance in terms of the conductivity, adsorption capacity, and electro-catalysis in MIL materials still needs to be further preferred in electrochemical sensors.

Based on the notation of Mordukhovich subdifferential in [27], we propose some of new concepts of convexity to establish optimality conditions for quasi ?-solutions for nonlinear semi-infinite optimization problems with data uncertainty in constraints. Moreover, some examples are given to illustrate the obtained results.