Facile fabrication of 3D structure of carrageenan gel at room temperature and spontaneous formation of carrageenan microgels

Abstract

Background

Carrageenan is a linear, charged polysaccharide that is commonly used as food hydrocolloids and drug carriers.

Methods

After differentiating the gelling mechanisms of hydrogen bond and cation-bridge, this study presents a novel and facile method for obtaining carrageenan hydrogel that can be easily shaped into capsules and free-standing films at room temperature.

Significant findings

In this work, the bio-natural polymer carrageenan is used to develop (1) weak gels for biodegradable 3D printing ink, and (2) spontaneously formed microgels that serve as a supporting medium for 3D printing. A weak gel based solely on hydrogen bonds is developed, which can subsequently be transformed into a strong gel by introducing cation bridges. Therefore, the weak gel can serve as biodegradable 3D printing ink for producing structures by injecting it into a supporting medium containing specific cations. When the carrageenan concentration is low, the bulk gel fails to form. However, the micron-sized microgel can still form spontaneously due to cation-bridges, rather than hydrogen bonds. The dispersion of carrageenan microgels shows both yield stress and viscoelasticity. Upon centrifugation, the concentrated dispersion displays self-healing ability and can serve as a supporting medium for 3D printing.