Tailoring the rheological properties of biosynthesized Copper oxide nanoparticles decorated Carboxymethyl cellulose hydrogels for biomedical applications

Nanoparticle-decorated hydrogels have seized substantial momentum in recent years, exclusively in biomedical research. In this investigation, Copper oxide nanoparticles decorated carboxymethyl cellulose hydrogels were prepared in an eco-friendly approach without using toxic cross-linkers. Initially, Copper oxide nanoparticles were prepared by biosynthesis approach to diminish the harmful effects of chemicals and to improve the biological activities using the leaf extract of Justicia adhatoda. The prepared nanoparticles were incorporated into the Carboxymethyl solution and carbopol to form a hydrogel by non-covalent interactions. X-ray diffraction analysis of CuO nanoparticles revealed a monoclinic crystalline structure without impurity. Rheological investigation of the pure hydrogel and CuO-decorated hydrogels revealed that CuO contributed to the enhancement of the hydrogel's mechanical performance. All the hydrogels demonstrated shear thinning behavior and better flow behavior index with the addition of CuO nanoparticles. The yield stress of the hydrogels was improved and found to be in the range of 61-79 Pa, which matches the ideal yield stress values in transdermal drug delivery. Storage moduli of hydrogels as a function of frequency was doubled (14-47.5 Pa), endorsing the involvement of CuO nanoparticles in crosslinking the polymeric matrix. Temperature and time sweep measurements revealed that the stability of the hydrogels also improved with the addition of CuO nanoparticles. The antibacterial activity of the hydrogels was evaluated using biofilm inhibition and showed better inhibition of 70 +/- 0.5%, 75 +/- 0.9%, 86 +/- 0.8%, and 83 +/- 0.8% against Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Enterococcus faecalis, respectively with increased concentration of CuO nanoparticles. The cell viability of the CuO-decorated hydrogels against MCF-7 and A431 was found to be 39% and 42%, respectively. Therefore, the eco-friendly biosynthesized CuO nanoparticles decorated hydrogels with improved mechanical properties can be employed in injectable and transdermal drug delivery systems.