Honeyberry-derived carbon quantum dots ameliorate LPS-induced neuroinflammation and oxidative stress through Nrf2/HO-1 signalling in HMC3 cells

Abstract

Carbon quantum dots (CQDs) were synthesized from blue honeysuckle (Lonicera caerulea) berry fruit extracts using a well-known, cost-effective, and environmental friendly hydrothermal process. The material was characterized using UV-vis spectroscopy, photoluminescence (PL), XPS, and TEM studies. The as-synthesized carbon dots exhibit excellent PL properties, with a quantum yield of ∼35.92%. CQDs vary in size from ∼2 nm to 9 nm. This study established the neuroprotective effects of CQDs against lipopolysaccharide (LPS)-induced human microglial cell model. LPS was found to induce cytotoxicity, reactive oxygen species, and pro-inflammatory cytokines interleukin (IL)-1β, IL-6, and tumour necrosis factor-α) and downregulated enzymatic antioxidants such as nuclear factor-erythroid factor 2-related factor 2 (Nrf2), superoxide dismutase, catalase, haem oxygenase (HO)-1, HO-2, and glutathione peroxidase, while CQDs treatment reversed LPS induced cytotoxicity, induced anti-inflammatory cytokines (IL-4, IL-10, and transforming growth factor β) and induce enzymatic antioxidants both at transcriptional and translational levels. The study suggested the potential role of CQDs prepared from Lonicera caerulea, as anti-inflammatory and antioxidative agents in neuroinflammatory and neurodegenerative diseases. In addition, CQDs could be exploited in various biomedical applications such as biosensing, drug delivery and tissue engineering.