A Novel Green Method for Producing Medical‐Grade Chitosan From <scp> <i>Loligo plei</i> </scp> Squid Pens

ABSTRACT This study presents an efficient, scalable method for producing medical‐grade chitosan from Loligo plei squid pens under milder, more sustainable processing conditions. High yields were achieved while preserving the integrity of the polymer chain by using gentle acid demineralization, moderate alkali concentrations, and fewer processing steps than in conventional deacetylation protocols. The resulting chitosan met stringent pharmacopeial standards, exhibiting endotoxin levels below 0.25 EU/mg, residual ash content under 1%, and undetectable levels of heavy metals. Notably, the CHDM45 sample exhibited both high deacetylation (&gt; 85%) and high viscosity (≥ 220 mPa s), making it suitable for advanced biomedical applications, including drug delivery systems, skin wound dressings, and bone engineering scaffolds. Furthermore, high‐quality chitosan was obtained without demineralization by leveraging the inherently low mineral content and purity of the L. plei squid pen. Structural, thermal, and elemental analyses confirmed the effectiveness of the milder process in maintaining desirable material properties. This approach maximizes the value of an underutilized fishery by‐product while minimizing environmental impact, aligning with principles of sustainable resource use and circular bioeconomy. As a result, L. plei emerges as a promising, sustainable source of biomedical‐grade chitosan, supporting innovation in biopolymer‐based materials and responsible waste valorization.