Green synthesis of gold nanoparticles mediated by extract of Curcuma longa under ultrasonic condition: Investigation of its application for reduction of dye pollutants and repairing the articular cartilage in an animal model of osteoarthritis of the knee

Abstract

For environmental remediation, it is crucial to find effective heterogeneous catalysts that can remove organic contaminants or convert them into chemicals that are safe and even valuable. Here, we present the synthesis of a green gold-based catalyst using an extract of Curcuma longa (Au NPs@C. longa) under ultrasonic condition. This nanocatalyst demonstrated good performance for reduction of organic dyes including methyl orange, methylene blue, and 4-nitrophenol. FE-SEM in conjunction with EDS, TEM, and UV–visible spectroscopy were used to evaluate the produced nanocatalyst. The Au NPs@C. longa should show great promise for wastewater treatment since it has the advantages of good activity, good kinetics and suitable stability for dye reduction. In the orthopedic experiments, the efficacy of Au NPs@C. longa on chondrogenesis was assessed by the primary cultured chondrocytes. Western blot, PCR, and histological assays were done to follow the underlying mechanisms. We evaluated the functional recovery after Au NPs@C. longa transplantation by an osteoarthritis articular cartilage injury model in knee. In immunological section, the Au NPs@C. longa reduced the levels of TNF-α, IL-1β, MMPs, and p-p65 expression. This may be caused by adjusting cellular redox homeostasis related to the Nrf2. The data indicated the positive efficacy of Au NPs@C. longa on stimulating chondrogenesisin vitro. It was revealed that the Au NPs@C. longa application speeded up the injury-induced dysfunction recovery after 21 days. The Au NPs@C. longa application suppressed the abnormal fibrosis and angiogenesis at the injury site.