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

Antonella Caterina Boccia,Ilaria Schizzi,Guido Scavia,Lucia Conzatti

doi:10.3390/molecules25112557

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 different 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 efficiency 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.

Highlights

Polysaccharides are natural and environmentally friendly polymers that have been used as starting materials for the production of a “new generation” of biobased materials because they are biocompatible, biodegradable, and nontoxic [1]
The purpose of this paper is to describe the synthesis of modified starch via enzymatic oxidation and the production of cryogels suitable as carriers of active molecules
The modified starches were thoroughly characterized by mono- and two-dimensional solution NMR spectroscopy to determine the degree of oxidation and the nature of newly formed functional groups

Summary

Introduction

Polysaccharides are natural and environmentally friendly polymers that have been used as starting materials for the production of a “new generation” of biobased materials because they are biocompatible, biodegradable, and nontoxic [1]. The sorption/desorption capability of the cryogels was evaluated using caffeine in water, chosen as a “model drug” for the presence of functional groups in the molecular structure able to interact with those on starch polymer chains, favoring a slower desorption phenomenon. This being a molecule that is a natural antioxidant by scavenging hydroxyl radicals, it is appropriate for biomedical applications to support the use of the proposed carrier [26]

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