Role of Sodium Dodecyl Sulfate in Tailoring the Rheological Properties of High-Strength Gelatin Hydrogels.

Virginia Martin Torrejon,Dongmei Wang,Guidong Luo,Bingjie Wu,Jim Song,Song Hang,Yanqiu Deng

doi:10.3390/gels7040271

Virginia Martin Torrejon, Dongmei Wang + Show 5 more

Open Access

https://doi.org/10.3390/gels7040271

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Abstract

Gelatin hydrogels are widely used materials that may require surfactants to adjust their solution’s surface tension for cell attachment, surface adsorption enhancement, or foaming. However, gelatin is a highly surface-active polymer, and its concentrated solutions usually do not require surfactants to achieve low surface tension. However, anionic surfactants, such as sodium dodecyl sulfate (SDS), interact strongly with gelatin to form complexes that impact its hydrogels’ rheological properties, influencing processability and functionality. Nevertheless, there is a lack of systematic research on the impact of these complexes on high gelatin content (i.e., high strength) hydrogels’ rheological properties. In this work, the SDS/gelatin ratio-dependent viscoelastic properties (e.g., gel strength, gelation kinetics, and melting/gelling temperature) of high-strength gelatin hydrogels were investigated using rheology and correlated to surface tension, viscometry, FTIR, and UV-Vis spectrophotometry. SDS–gelatin ratio was proved to be an important factor in tailoring the rheological properties of gelatin hydrogels. The gel strength, gelation kinetics, and melting/gelling temperature of the gelatin hydrogels linearly increased with SDS incorporation up to a maximum value, from which they started to decline. The findings of this work have wide applicability in tailoring the properties of gelatin–SDS solutions and hydrogels during their processing.

Highlights

Hydrogels from natural polymers have attracted research and development attention for a wide range of applications due to their biodegradability, biocompatibility, and ability to mimic living tissues’ characteristics [1,2,3]
Surfactants can alter gelatin hydrogels’ properties due to protein reconfiguration and complex formation caused by gelatin–surfactant interactions
UV-Vis spectrophotometry results confirmed the solubility of the the gelatin–Sodium dodecyl sulfate (SDS) complexes at their natural pH and the temperature at which the characgelatin–SDS complexes at their natural pH and the temperature at which the characterizaterization was performed

Summary

Introduction

Hydrogels from natural polymers have attracted research and development attention for a wide range of applications due to their biodegradability, biocompatibility, and ability to mimic living tissues’ characteristics [1,2,3]. It is important to tailor their mechanical strength, rheological properties, and thermal stability to meet their target functional and processing requirements [7,8,9] These can be achieved by formulation (e.g., gelatin concentration and incorporation of surfactants, crosslinkers, nanomaterials, or polymers) and the selection of processing methods and conditions (e.g., thermally induced phase separation, foaming, 3D printing, electrospinning, and porogen leaching) which can alter the gelatin hydrogels’ molecular structure and properties [7,8,9,10,11]. Surfactants can alter gelatin hydrogels’ properties due to protein reconfiguration and complex formation caused by gelatin–surfactant interactions. As surfactant concentration increases in aqueous solutions, the surface tension usually decreases until reaching the critical micelle concentration (CMC). Surfactants are not usually suitable for further decreasing the surface tension in concentrated gelatin solutions [21]

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