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Spider silk, relying on its exceptional mechanical properties,has attracted extensive attention throughout the world.The structure of a material can influence its mechanical properties.Investigation of the structure of spider silk includes amino acid composition, molecular structure, self-assembly, and crystallization,among other characteristics.Herein,the effects of concentration,time,alkali metal ions( Na+and K+) and pH on the conformational transition and self-assembly of regenerated Ornithoctonus huwena spider dragline silk protein( spidroin) in water were investigated using circular dichroism( CD) and atomic force microscopy( AFM).Spidroin concentration,time and Na+ions slightly influenced the conformational transition of spidroin molecules.However,K+ions and pH induced the formation of a β-sheet structure.Increasing spidroin concentration or time increased the aggregation of spidroin and enhanced the formation of nanofilaments.K+ions enhanced the self-assembly of spidroin into nanofilaments.The self-assembled nanofilaments appeared at a pH of approximately 6.11.Both lower and higher pH induced aggregation.At a lower pH, the aggregation was composed of nanoparticles, whereas higher pH induced the aggregation of nanofilaments,likely from the synergistic effect of Na+ions and pH.
Spider silk, relying on its exceptional mechanical properties, has been remarkably characterized throughout the world. The structure of a material can influence its mechanical properties. Investigation of the structure of spider silk includes amino acid composition, molecular structure, self-assembly, and crystallization , among other characteristics. Heresin, the effects of concentration, time, alkali metal ions (Na + and K +) and pH on the conformational transition and self-assembly of regenerated Ornithoctonus huwena spider dragline silk protein (spidroin) in water were investigated using circular dichroism (CD) and atomic force microscopy (AFM) .Spidroin concentration, time and Na + ions slightly influenced the conformational transition of spidroin molecules. Still, K + ions and pH induced the formation of a β-sheet structure. Increasing spidroin concentration or time increased the aggregation of spidroin and enhanced the formation of nanofilaments. K + ions enhanced the self-assembly of spidroin into n anofilaments. The self-assembled nanofilaments had a pH of approximately 6.11.Both lower and higher pH induced aggregation. At a lower pH, the aggregation was composed of nanoparticles, whereas higher pH induced the aggregation of nanofilaments, likely from the synergistic effect of Na + ions and pH.