*Article* **Biobased Cryogels from Enzymatically Oxidized Starch: Functionalized Materials as Carriers of Active Molecules**

### **Antonella Caterina Boccia 1,\*, Guido Scavia 1, Ilaria Schizzi 2 and Lucia Conzatti 2**

1 Institute for Chemical Sciences and Technologies-SCITEC "G. Natta", CNR, Via Corti, 12, 20133 Milano, Italy; guido.scavia@scitec.cnr.it


Academic Editors: Carlos A. García-González, Pasquale Del Gaudio and Ricardo Starbird Received: 20 April 2020; Accepted: 28 May 2020; Published: 31 May 2020

**Abstract:** Starch recovered from an agrifood waste, pea pods, was enzymatically modified and used to prepare cryogels applied as drug carriers. The enzymatic modification of starch was performed using the laccase/(2,2,6,6-tetramethylpiperidin-1-yl)oxyl TEMPO system, at a variable molar ratio. The characterization of the ensuing starches by solution NMR spectroscopy showed partial conversion of the primary hydroxyl groups versus aldehyde and carboxyl groups and successive creation of hemiacetal and ester bonds. Enzymatically modified starch after simple freezing and lyophilization process provided stable and compact cryogels with a morphology characterized by irregular pores, as determined by atomic force (AFM) and scanning electron microscopy (SEM). The application of cryogels as carriers of active molecules was successfully evaluated by following two di fferent approaches of loading with drugs: a) as loaded sponge, by adsorption of drug from the liquid phase; and b) as dry-loaded cryogel, from a dehydration step added to loaded cryogel from route (a). The e fficiency of the two routes was studied and compared by determining the drug release profile by proton NMR studies over time. Preliminary results demonstrated that cryogels from modified starch are good candidates to act as drug delivery systems due to their stability and prolonged residence times of loaded molecules, opening promising applications in biomedical and food packaging scenarios.

**Keywords:** cryogel; starch; NMR spectroscopy; morphology; drug release
