Thermo- and pH-Responsive Gelatin/Polyphenolic Tannin/Graphene Oxide Hydrogels for Efficient Methylene Blue Delivery.

Ariel C De Oliveira,Paulo R Souza,Manuel E G Winkler,Eduardo Radovanovic,Alessandro F Martins,Artur J M Valente,Bruno H Vilsinski,Wilker Caetano,Edvani C Muniz,Marcos L Bruschi

doi:10.3390/molecules26154529

Abstract

Gelatin (GE), amino-functionalized polyphenolic tannin derivative (TN), and graphene oxide (GO) were associated to yield thermo- and pH-responsive hydrogels for the first time. Durable hydrogel assemblies for drug delivery purposes were developed using the photosensitizer methylene blue (MB) as a drug model. The cooling GE/TN blends provide brittle physical assemblies. To overcome this disadvantage, different GO contents (between 0.31% and 1.02% wt/wt) were added to the GE/TN blend at 89.7/10.3 wt/wt. FTIR and RAMAN spectroscopy analyses characterized the materials, indicating GO presence in the hydrogels. Incorporation studies revealed a total MB (0.50 mg/mL) incorporation into the GE/TN-GO hydrogel matrices. Additionally, the proposed systems present a mechanical behavior similar to gel. The GO presence in the hydrogel matrices increased the elastic modulus from 516 to 1650 Pa. SEM revealed that hydrogels containing MB present higher porosity with interconnected pores. Dissolution and swelling degree studies revealed less stability of the GE/TN-GO-MB hydrogels in SGF medium (pH 1.2) than SIF (pH 6.8). The degradation increased in SIF with the GO content, making the polymeric matrices more hydrophilic. MB release studies revealed a process controlled by Fickian diffusion. Our results point out the pH-responsible behavior of mechanically reinforced GE/TN-GO-MB hydrogels for drug delivery systems purposes.

Highlights

Protein-based materials have been extensively used in biomedical applications due to their cytocompatibility and biodegradability
To prevent this premature reduction, to increase the methylene blue (MB) retention time in contact with the target cells, and promote the controlled delivery of MB, we propose the development of GE/tannin derivative (TN)-graphene oxide (GO)-MB hydrogels
Results of of the theswelling swellingdegree degreeobtained obtainedfor forthe theGE/TN-GO-MB

Summary

Introduction

Protein-based materials have been extensively used in biomedical applications due to their cytocompatibility and biodegradability. Physical hydrogel assemblies have received great attention because of their advantages compared to chemical hydrogels These materials can be designed to avoid toxic chemistries (crosslinkers, organic solvents, and surfactants), which crosslink protein chains to support durability, using one-step strategies (in situ methods) [1]. These matrices comprise three-dimensional and hydrophilic structures (amine (–NH2 ), thiol (–SH), hydroxyl (–OH), and carboxyl (–COOH) groups) capable of absorbing biological fluids and swelling. These sites enable the incorporation of hydrophilic drugs within the hydrogel matrices by establishing electrostatic, H-bonding, and iondipole forces [2]

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Results

Conclusion