Carbon nanodots (CNDs) have shown good antioxidant capabilities by scavenging oxidant free radicals such as diphenyl-1-picrylhydrazyl radical (DPPH•) and reactive oxygen species. While some studies suggest that the antioxidation activities associate to the proton donor role of surface active groups like carboxyl groups (–COOH), it is unclear how exactly the extent of oxidant scavenging potential and its related mechanisms are influenced by functional groups on CNDs’ surfaces. In this work, carboxyl and the amino functional groups on CNDs’ surfaces are modified to investigate the individual influence of intermolecular interactions with DPPH• free radical by UV-Vis spectroscopy and electrochemistry. The results suggest that both the carboxyl and the amino groups contribute to the antioxidation activity of CNDs through either a direct or indirect hydrogen atom transfer reaction with DPPH•.

Despite the potential health benefits of curcumin, such as antioxidant, anticancer, anti-inflammatory, and antimicrobial properties, its usage is limited by poor bioavailability and low aqueous solubility. Nano-formulations of curcumin have gained a lot of attention due to their increased bioavailability, solubility, circulation times, targeted specificity, decreased biodegradation, better stability, and improved cellular uptake. The current study aimed to enhance the bioavailability of curcumin using carbon nanodots (CNDs) as loading vehicles to deliver curcumin due to their excellent biocompatibility, aqueous solubility, and photoluminescence properties. Two types of CNDs (E-CNDs and U-CNDs) were used for curcumin loading and characterized for particle size, morphology, loading capability (measured as adsorption efficiency and loading capacity), stability, photoluminescence properties, in vitro drug release studies, cellular uptake, and anticancer activity. The prepared curcumin-loading CNDs (Curc-CNDs) displayed sizes around or below 10 nm with good stability. The Curc-E-CNDs demonstrated a curcumin adsorption efficiency of 91% in solution, while the Curc-U-CNDs have an adsorption efficiency of 82%. Both have a loading capacity of 3.4–3.8% with respect to the weight of the CNDs. Curcumin release followed a controlled sustained pattern that a total of 60% and 74% of curcumin was released at 72 h from Curc-E-CNDs and Curc-U-CNDs, respectively, in pH 5 buffer, and almost 90% was released in culture media within 96 h. Both of the Curc-CNDs were uptaken by cells and exhibited prominent cytotoxicity toward cancer cells. The results clearly depict the role of CNDs as efficient carriers for curcumin delivery with prolonged release and enhanced bioavailability, thereby improving the overall antitumor activity.

The light-induced property of photosystem I (PSI) has been utilized to convert solar energy to electrical energy in photoelectrochemical cells.Here we provide new results on the relationship between surface plasmon generation (SPG) efficiency of nanoslits and the experimentally obtained photocurrent by immobilizing PSI on the gold nanoslit electrode surfaces regarding different nanoslit widths. The photocurrent increases with the increment of SPG efficiency. This finding can be attributed to the phenomenon of plasmon−exciton coupling effect on the PSI in the nanoslits. The enhancement of photocurrent generation is discussed on the basis of plasmonic light trapping and plasmon-induced resonance energy transfer.

Increasing the performance of energy storage systems using different metal oxides and carbon nanomaterial as support scaffolds in electrode manufacture is of great importance. However, deposition of active material using binders or conductive agents results in reduced effective contact areas in the electrodes and between the electrolytes, lowering the energy storage capacity. In this work, a homogeneous and stable low current electrodeposition of binary metal oxides MnO2/Co3O4 on superaligned electrospun carbon nanofibers (SA-ECNFs) greatly overcomes these shortcomings. The morphology tests revealed that the manganese oxide (MnO2) and cobalt oxide (Co3O4) were uniformly wrapped around the carbon nanofibers to form a porous morphology, rendering high energy storage capacity from both the pseudocapacitance and electrochemical double layer (ECDL). Electrochemical tests indicated that the as-prepared MnO2/Co3O4@SA-ECNFs electrode displays a specific capacitance of 728 F g–1 in 6 M KOH electrolyte in CV vs 622 F g–1 of MnO2@SA-ECNFs electrode at 5 mV s–1. The performance of galvanic charge–discharge (GCD) at 2 A g–1 of the electrode demonstrated 64.5 Wh kg–1 for energy density and 1276 W kg–1 for power density and a capacity retention of 71.8% over 11 000 cycles.

Transition metal oxides can introduce high pseudocapacitance to an electric double layer capacitor for storing more electrical charges. Their role can be more than that since they possess high dielectric constant. Here, we propose a self-sustainable bi-functional configuration by eliminating traditional separator of a metal oxide film supercapacitor that is capable of providing good energy storage performance. We take advantage of super-aligned electrospun carbon nanofibers (SA-ECNFs) as an interconnected scaffold, coupling with electrochemical deposition of α-MnO2 layers at different currents to introduce pseudocapacitance while providing dielectric layer functioning as a separator to assemble a state-of-the-art supercapacitor. The good electrochemical performance of galvanic charge-discharge specific capacitance at 141 F g −1 and energy density at 12.5 Wh kg −1 offers the promising applications in the energy storage field.