Session: 02-15-01: BioManufacturing and Biomaterials

Paper Number: 70392

Start Time: Friday, 03:05 PM

70392 - Synthesis-Structure-Property Relationship for Ultra-Soft Tissue-Equivalent Alginate Hydrogel 

This study investigates the influence of processing parameters on the mechanical behavior of alginate hydrogels for use in soft deformable structures. Such structures are attracting considerable attention for advanced engineering applications due to their unique properties compared to traditional engineering structures. These properties include mechanical tissue compatibility, large deformation, and the relative ease of tailoring the properties to meet specific needs.  Some of the advanced applications for which the materials are being explored include tissue-equivalent phantoms, cell-laden scaffolds for tissue engineering, soft robots, and stretchable electronics. Although the concept of soft deformable structures has existed for a long time, it still remains a challenge to produce structures with mechanical properties that are similar to soft tissues. The production of such structures relies critically on the mechanical properties of the material. Hydrogels have emerged in recent years as a viable candidate for such purposes.  Hydrogels are hydrophilic polymers with 3D network. They are highly absorbent and contain over 90% water without being dissolved. Alginate, which is obtained from brown seaweeds, is one of the most widely used hydrogels with properties that are similar to extra cellular matrix (ECM). Thus, the mechanical behavior of alginate is naturally close to that of soft tissue.  In addition, the reaction conditions for the gelling of alginate is favorably mild. Gelling can be initiated only in the presence of divalent cations, for example, Ca²⁺, Mg²⁺, and Ba²⁺, and the gelling rate is quite fast, which makes hydrogels desirable for production of tissue-equivalent soft deformable structures.

This study aims to determine the synthesis-structure-property relationship for alginate hydrogel with Young’s modulus in the range of 10¹~10² kPa, equivalent to human lungs of varying pathological conditions.  Most previous studies have focused on improvement of the Young’s modulus and elongation of alginate. In contrast, the present study focuses on characterizing the influence of processing parameters on the mechanical behavior of alginate. Specifically, the influence of alginate concentration and ratio of calcium ion to carboxyl group are evaluated while the Young’s modulus of the hydrogel is carefully controlled within the desired tissue-equivalent range. The alginate hydrogel is prepared by direct mixture of sodium alginate and CaCO₃, followed by the addition of D-glucono-δ-lactone (GDL) to initiate the gelling process to form structurally uniform gels. FTIR is used to characterize the influence of synthesis parameters on the chemical bonds. Elongation testing is performed to obtain the Young’s modulus of the material. An empirical relation is developed between the synthesis parameters and the mechanical behavior of the material. The result of the study will be used subsequently to guide the additive manufacturing of soft deformable phantoms of human lungs for radiotherapy application.

Presenting Author: Xiangpeng Li University of Central Florida

Authors:

Xiangpeng Li University of Central Florida
Jihua Gou University of Central Florida
Olusegun J. Ilegbusi University of Central Florida