Hidrogel de colágeno contendo BaTiO3NP e MWCNT-COOH para a bioengenharia de tecido ósseo

Abstract

Nanostructured collagen hydrogels (COL) with nanomaterials (NMs) are promising for bone tissue bioengineering. Barium Titanate Nanoparticles (BaTiO3 NP) present piezoelectric characteristics and ability to form dipoles, while Multilayer Carboxylated Carbon Nanotubes (MWCNT-COOH) are good electrical conductors and exhibit antimicrobial activity. These are desirable properties in osteoinductive hydrogels and for clinical application in bone regeneration. We hypothesize that the nanostructured hydrogel containing COL/BaTiO3 NP/MWCNT-COOH has improved mechanical and electrical properties, is cytocompatible, antibacterial and promotes the maturation of primary osteoblasts from neonatal Wistar rats (rOB). In this study, the objective was to characterize physical, electrochemical and mechanical properties, evaluate cytocompatibility and investigate the antibacterial, osteoinductive and osteogenic bioactivity of these hydrogels containing 1, 10 and 100 µg/mL of MWCNT-COOH (named NTB/NTC1, NTB/NTC10 and NTB/NTC100) in comparison to hydrogels with only COL and COL/BaTiO3 NP (named NTB). The characterization analyses indicated an improvement (p<0.05) in the mechanical strength of hydrogels containing MWCNTCOOH (NTB/NTC groups; p<0.05) in comparison to the COL and NTB groups. Furthermore, NTB/NTC10 presented greater electrical conductivity compared to the other groups (p<0.05). Cytocompatibility data with rOBs showed good morphology evaluated by light microscopy, cell viability evaluated by MTT and Alamar Blue, and regularized superoxide dismutase enzyme activity in all groups of hydrogels tested NTB/NTC compared to COL and NTB (p>0.05), over 14 days of culture. Bioactivity data demonstrated that the incorporation of MWCNT-COOH in the hydrogels increased the antibacterial activity, mainly against Escherichia coli, in the NTB/NTC10 group (p<0.05). Given the good results of NTB/NTC10 in the mechanical, electrical and antibacterial evaluations, this group was evaluated (compared to COL and NTB) for rOB maturation and bone formation. Although there was no difference in alkaline phosphatase activity (p>0.05), mineralization nodules were identified in greater quantity by Alizarin Red S (p<0.05) and Von Kossa in NTB and NTB/NTC10 compared to COL, even in the absence of inducers in the culture medium. Finally, COL I gene expression was downregulated, while OCN and RUNX2 were upregulated in rOBs cultured in NTB/NTC10 compared to COL and NTB groups. These data demonstrate that the association of BaTiO3 and MWCNT-COOH in COL matrix as in the proposed NTB/NTC10 hydrogel increased the capacity for bone formation in a spontaneous and cytocompatible manner and is promising for application in bioengineering and bone tissue regeneration.