Antibacterial Properties of Curcumin Loaded Graphene Oxide Flakes

Potentiation of Antimicrobial Photodynamic Therapy by Curcumin Loaded Graphene Quantum Dots

Increasing resistance to existing antibiotics by microbes is currently the biggest dilemma. Antimicrobial photodynamic therapy is a promising alternative for treatment of multidrug resistant infections. The aim of current study was to fabricate graphene quantum dots loaded with curcumin as photosensitizer for improved antimicrobial photodynamic therapy. The study involved fabrication of blank and curcumin-loaded graphene quantum dots, their characterizations (TEM, UV-visible & fluorescence emission spectra), cytotoxicity assay, ROS assay and investigation of enhanced antimicrobial photodynamic effect against resistant microbes. The fabrication of blank and loaded graphene quantum dots was confirmed by observation of peak shift and changes in peak intensity of blank graphene quantum dots, curcumin alone compared to curcumin loaded graphene quantum dots in UV-visible and fluoresce emission spectra. Cytotoxicity assay showed that 100 µM concentration was not toxic to NIH/3t3 fibroblasts. In ROS assay, the curcumin loaded formulation showed threefold increase in ROS production. Blue light (405 nm) irradiance of 30 J/cm² and photosensitizer concentration of 100 µM showed ~3.5 log₁₀ enhanced CUF reduction against Pseudomonas aeruginosa, MRSA, Escherichia coli, and Candida albicans. In conclusion, curcumin-loaded graphene quantum dots shoed enhanced antimicrobial photodynamic effects and can be used as an alternative effective treatment for resistant infections.

Graphene-Based Sensors for the Detection of Bioactive Compounds: A Review

Over the last years, different nanomaterials have been investigated to design highly selective and sensitive sensors, reaching nano/picomolar concentrations of biomolecules, which is crucial for medical sciences and the healthcare industry in order to assess physiological and metabolic parameters. The discovery of graphene (G) has unexpectedly impulsed research on developing cost-effective electrode materials owed to its unique physical and chemical properties, including high specific surface area, elevated carrier mobility, exceptional electrical and thermal conductivity, strong stiffness and strength combined with flexibility and optical transparency. G and its derivatives, including graphene oxide (GO) and reduced graphene oxide (rGO), are becoming an important class of nanomaterials in the area of optical and electrochemical sensors. The presence of oxygenated functional groups makes GO nanosheets amphiphilic, facilitating chemical functionalization. G-based nanomaterials can be easily combined with different types of inorganic nanoparticles, including metals and metal oxides, quantum dots, organic polymers, and biomolecules, to yield a wide range of nanocomposites with enhanced sensitivity for sensor applications. This review provides an overview of recent research on G-based nanocomposites for the detection of bioactive compounds, providing insights on the unique advantages offered by G and its derivatives. Their synthesis process, functionalization routes, and main properties are summarized, and the main challenges are also discussed. The antioxidants selected for this review are melatonin, gallic acid, tannic acid, resveratrol, oleuropein, hydroxytyrosol, tocopherol, ascorbic acid, and curcumin. They were chosen owed to their beneficial properties for human health, including antibiotic, antiviral, cardiovascular protector, anticancer, anti-inflammatory, cytoprotective, neuroprotective, antiageing, antidegenerative, and antiallergic capacity. The sensitivity and selectivity of G-based electrochemical and fluorescent sensors are also examined. Finally, the future outlook for the development of G-based sensors for this type of biocompounds is outlined.