Thermo- and pH-Responsive Gelatin/Polyphenolic Tannin/Graphene Oxide Hydrogels for Efficient Methylene Blue Delivery
Ariel C. de Oliveira,
Paulo R. Souza,
Bruno H. Vilsinski,
Manuel E. G. Winkler,
Marcos L. Bruschi,
Eduardo Radovanovic,
Edvani C. Muniz,
Wilker Caetano,
Artur J. M. Valente,
Alessandro F. Martins
Affiliations
Ariel C. de Oliveira
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
Paulo R. Souza
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
Bruno H. Vilsinski
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
Manuel E. G. Winkler
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
Marcos L. Bruschi
Laboratory of Research and Development of Drug Delivery Systems, Department of Pharmacy, State Univesity of Maringá (UEM), 5970 Colombo Avenue, Maringá 87020-900, PR, Brazil
Eduardo Radovanovic
Department of Chemistry, State University of Maringa, Maringá 87020-900, PR, Brazil
Edvani C. Muniz
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
Wilker Caetano
Núcleo de Pesquisas em Sistemas Fotodinâmicos, Chemistry Department, State University of Maringá, Maringá 87020-900, PR, Brazil
Artur J. M. Valente
Department of Chemistry, CQC, University of Coimbra, 3004-535 Coimbra, Portugal
Alessandro F. Martins
Group of Polymeric Materials and Composites, Department of Chemistry, State University of Maringá (UEM), Maringá 87020-900, PR, Brazil
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.
