Double Cross-linked Methacrylated Carboxymethyl Pea Starch Cryogels with Highly Compressive Elasticity and Hemostatic Function

As an abundant renewable natural material, starch has attracted unprecedented interest in the biomedical field. Carboxylated starch particles have been investigated for topical hemostasis, but the powder may not provide physical protection or support for wounds. Here, we prepared macroporous cryogel sponges of methacrylated carboxymethyl starch (CM-ST-MA) containing a covalent and a calcium ionic double network. The second ionic cross-linking network enhanced the compressive strength and toughness dramatically but reduced the swelling ratios. Cryogels and sponges exhibited excellent compressive elasticity at low Ca²⁺ concentrations (0.01 M). Cryogels became more plastic and dry sponges became rigid and brittle at high Ca²⁺ concentrations. The cryogels have outstanding wet-thermal stability but are still degradable via enzymatic hydrolysis. All CM-ST-MA sponges showed excellent biocompatibility, hemocompatibility, and outstanding hemostasis in in vitro assays. In the in vivo mouse tail amputation model, both CM-ST-MA cryogels without or with Ca²⁺ (0.01 M) reduced the blood loss and bleeding time significantly.