Effect of gum Arabic on antifungal photodynamic activity of curcumin against Botrytis cinerea spores

This study investigated the effect of gum Arabic on curcumin's phototoxicity against Botrytis cinerea, a significant cause of postharvest losses in horticultural produce. Curcumin-loaded nanoparticle suspensions and emulsions stabilized with gum Arabic were prepared and their absorbance, fluorescence emission, physicochemical properties, antimicrobial photodynamic activity (using response surface methodology (RSM)), and reactive oxygen species (ROS) generation (via electron paramagnetic resonance (EPR) spectroscopy) were evaluated. Fluorescence emission exhibited a blue shift (510-550 nm) in both formulations, with emulsions showing higher intensities due to a more hydrophobic environment. Gum Arabic concentration significantly influenced the physicochemical properties of both suspensions, with nanoparticle size decreasing from 572.80 nm to 202.80 nm as gum Arabic concentration increased from 0.5 % to 2.5 % (at 65 μM curcumin). Nanoparticle suspensions demonstrated higher antimicrobial efficacy, reducing B. cinerea spores by 0.39-3.40 log10(CFU.ml-1), compared to 0.00-0.46 log10(CFU.ml-1) in emulsions. The phototoxic effect was dependent on curcumin concentration and light irradiance, as demonstrated by RSM. EPR confirmed the generation of superoxide anion and hydroxyl radicals in both formulations, which indicated a Type I photodynamic mechanism, with nanoparticle suspensions having a sustained ROS generation. Overall, gum Arabic did not impair curcumin's antifungal photodynamic activity, making it as a promising stabiliser for curcumin-based treatments.

Hybrid Zn-β-Aminoporphyrin-Carbon Nanotubes: Pyrrolidine and Direct Covalent Linkage Recognition, and Multiple-Photo Response

To unveil and shape the molecular connectivity in (metallo)porphyrin-carbon nanotube hybrids are of main relevance for the multiple medicinal, photoelectronic, catalytic, and photocatalytic applications of these materials. Multi-walled carbon nanotubes (MWCNTs) were modified through 1,3-dipolar cycloaddition reactions with azomethine ylides generated in situ and carrying pentafluorophenyl groups, followed by immobilization of the β-amino-tetraphenylporphyrinate Zn(II). The functionalities were confirmed via XPS and FTIR, whereas Raman spectroscopy showed disruptions on the graphitic carbon nanotube surface upon both steps. The functionalization extension, measured via TGA mass loss and corroborated via XPS, was 0.2 mmol·g-1. Photophysical studies attest to the presence of the different porphyrin-carbon nanotube connectivity in the nanohybrid. Significantly different emission spectra and fluorescence anisotropy of 0.15-0.3 were observed upon variation of excitation wavelength. Vis-NIR absorption and flash photolysis experiments showed energy/charge transfer in the photoactivated nanohybrid. Moreover, evidence was found for direct reaction of amino groups with a carbon nanotube surface in the presence of molecular dipoles such as the zwitterionic sarcosine amino acid.

Single-chirality of single-walled carbon nanotubes (SWCNTs) through chromatography and its potential biological applications

Gel chromatography is used to separate single-chirality and selective-diameter SWCNTs. We also explore the use of photothermal therapy and biosensor applications based on single-chirality, selected-diameter, and unique geometric shape.

All-perylene-derivative for white light emitting diodes

Tb(H3PTC)3PTCDAAn organic-based bright white light emitting compound, namely Tb(H3PTC)3, able to be used as part of a WOLED and as a part of a RGB system that can withstand high temperatures (∼700 K), is developed using PTCDA and Tb(NO₃)₃·5H₂O as precursors by hydrothermal synthesis.

Flower-like silver bismuthate supported on nitrogen-doped carbon dots modified graphene oxide sheets with excellent degradation activity for organic pollutants

In this study, a new ternary AgBiO₃/GO/NCDs composite (GO = graphene oxide, NCDs = nitrogen-doped carbon dots) has been successfully prepared through in-situ growth of flower-like AgBiO₃ on GO/NCDs complex support. The AgBiO₃/GO/NCDs composite exhibits significantly enhanced degradation activities towards organic pollutants of rhodamine B, phenol and tetracycline. Especially, the refractory tetracycline (20 mg L^-1) can be completely removed within 6.0 min with a dosage of 30 mg of AgBiO₃/GO/NCDs under the assistance of peroxymonosulfate (PMS, 0.2 mM). It is revealed that GO in the composite can facilitate the quick and efficient electron transfer and improve the generation of reactive oxygen species during the degradation process, while the NCDs may play double roles as both the electron-acceptor and the reactive site. Besides, the electrons can be captured by PMS to produce plenty of sulfate radicals (SO₄^-) with very strong oxidation ability. All these factors collaboratively promote the degradation efficiency of AgBiO₃/GO/NCDs towards organic pollutants. The excellent degradation activities of AgBiO₃/GO/NCDs endow it with potential application in wastewater purification.