**Controlled Delivery of Insulin-like Growth Factor-1 from Bioactive Glass-Incorporated Alginate-Poloxamer**/**Silk Fibroin Hydrogels**

#### **Qing Min 1,**†**, Xiaofeng Yu 2,**†**, Jiaoyan Liu 2, Yuchen Zhang 1, Ying Wan 2,\* and Jiliang Wu 1,\***


Received: 22 April 2020; Accepted: 11 June 2020; Published: 20 June 2020

**Abstract:** Thermosensitive alginate–poloxamer (ALG–POL) copolymer with an optimal POL content was synthesized, and it was used to combine with silk fibroin (SF) for building ALG–POL/SF hydrogels with dual network structure. Mesoporous bioactive glass (BG) nanoparticles (NPs) with a high level of mesoporosity and large pore size were prepared and they were employed as a vehicle for loading insulin-like growth factor-1 (IGF-1). IGF-1-loaded BG NPs were embedded into ALG–POL/SF hydrogels to achieve the controlled delivery of IGF-1. The resulting IGF-1-loaded BG/ALG–POL/SF gels were found to be injectable with their sol-gel transition near physiological temperature and pH. Rheological measurements showed that BG/ALG–POL/SF gels had their elastic modulus higher than 5kPa with large ratio of elastic modulus to viscous modulus, indicative of their mechanically strong features. The dry BG/ALG–POL/SF gels were seen to be highly porous with well-interconnected pore characteristics. The gels loaded with varied amounts of IGF-1 showed abilities to administer IGF-1 release in approximately linear manners for a few weeks while e ffectively preserving the bioactivity of encapsulated IGF-1. Results sugges<sup>t</sup> that such constructed BG/ALG–POL/SF gels can function as a promising injectable biomaterial for bone tissue engineering applications.

**Keywords:** alginate–poloxamer copolymer; silk fibroin; dual network hydrogel; mesoporous bioactive glass; insulin-like growth factor-1
