CHEMICAL COMPOSITION, STRUCTURE, AND PROPERTIES OF NATURAL SILK: A COMPREHENSIVE REVIEW

Natural silk is a high-performance biopolymer fiber produced by Bombyx mori silkworms and various spider species. It is composed primarily of two proteins—fibroin and sericin—which endow silk with its unique combination of mechanical strength, biocompatibility, and biodegradability. This article reviews the chemical composition, molecular architecture, and physicochemical properties of silk, with emphasis on the crystalline beta-sheet domains of fibroin, the role of sericin as a protective coating, and the hydrogen-bonding network that governs fiber performance. Thermal stability, solubility behavior, and response to chemical treatments are discussed in detail. The article also surveys current chemical modification strategies, including degumming, fibroin dissolution, and regeneration protocols. Understanding silk chemistry at the molecular level is critical for expanding its applications in biomedicine, textile engineering, and functional materials. This review synthesizes findings from eight primary research sources to provide a rigorous chemical perspective on this remarkable natural polymer.