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Priyadarshi, Ruchir, Zohreh Riahi, and Jong-Whan Rhim. Sustainable Materials and Technologies 40 (2024): e00942.
Sulfur quantum dots (SQDs) have been effectively utilized in the formulation of alginate-based functional coatings for kraft paper, aimed at enhancing food packaging performance. This study highlights the integration of SQDs, with or without grapefruit seed extract (GFSE), into sodium alginate matrices to produce coatings with superior antioxidant and antimicrobial properties.
The incorporation of 5 wt% SQDs into the coating formulation resulted in nearly complete (~100%) scavenging of ABTS radicals and 60% reduction in DPPH radicals, indicating outstanding antioxidant potential. Moreover, SQDs exhibited significant antibacterial activity, reducing E. coli and L. monocytogenes viability by approximately 2 log CFU/mL and 4.5 log CFU/mL, respectively. Notably, co-addition of SQDs and GFSE (2.5 wt% each) achieved synergistic effects, completely eliminating L. monocytogenes and reducing E. coli by ~3 log CFU/mL.
The SQD-based coatings also improved the mechanical integrity and oil resistance of kraft paper by filling interfibrillar gaps. Although water vapor permeability slightly increased due to the hydrophilic nature of the components, the functional coatings significantly inhibited lipid oxidation in packaged hash brown patties, reducing oxidation by nearly 50% over 15 days of storage.
This work underscores the potential of sulfur quantum dots as multifunctional nanomaterials in active packaging systems to enhance food preservation and safety.
Lu, Y., Zhao, J., Zhao, G., Yi, P., Duan, L., Sun, H., ... & Meng, Q. (2025). Journal of Colloid and Interface Science, 137352.
Sulfur quantum dots (SQDs), a class of environmentally friendly, non-metallic nanomaterials, have recently emerged as promising visible-light-active photocatalysts. In this study, sulfur quantum dots modified with α-cyclodextrin (CD-S dots) were synthesized via a hydrothermal method to catalyze the dehydrogenative cross-coupling of alcohols and amines under mild conditions.
The photocatalytic transformation was conducted in an aqueous medium under visible light (10 W purple LED) at room temperature. A representative reaction involved benzyl alcohol and 3-chlorobenzylamine as substrates in the presence of CD-S dots, leading to the efficient formation of imine products. The process demonstrated high chemoselectivity and functional group tolerance, with the final product isolated through solvent extraction and chromatographic purification.
This work underscores the capacity of sulfur quantum dots to facilitate oxidative coupling reactions without the need for precious metals or harsh conditions. The α-cyclodextrin modification enhances the dispersion and stability of SQDs in aqueous media, contributing to the catalytic efficiency under ambient conditions.
These findings position sulfur quantum dots as a sustainable and effective photocatalyst for organic synthesis, particularly in green chemistry applications involving visible-light-driven transformations.
Guo, Tao, et al. Microchemical Journal 209 (2025): 112642.
In this study, sulfur quantum dots (SQDs) were employed to fabricate a high-sensitivity electrochemical sensor for the detection of mancozeb (MCZ), an environmentally hazardous fungicide. SQDs were synthesized via top-down alkali etching of elemental sulfur powder and subsequently dispersed in a Nafion solution to form a stable coating suspension.
Prior to modification, the glassy carbon electrode (GCE, 3 mm diameter) was meticulously polished with 0.05 μm Al₂O₃ powder to achieve a smooth surface, followed by sequential rinsing with ultrapure water and ethanol. A mixture containing 1 mg·mL⁻¹ SQDs and 20 wt% Nafion was sonicated for 30 minutes to ensure uniform dispersion. A 3 μL aliquot of this suspension was drop-cast onto the GCE surface and air-dried at room temperature.
For enhanced performance, cyclic voltammetry (-0.5 to 1.0 V, scan rate 200 mV/s) was conducted in phosphate buffer solution (PBS, pH 7.0) for 40 cycles to activate the modified surface. A final 10 μL coating of SQDs-Nafion solution was applied to the active area of a screen-printed electrode and dried naturally, resulting in a stable and reproducible SQD-modified electrode.
This SQD-based sensor demonstrated a low detection limit (432.7 nM) and excellent selectivity for MCZ, offering a practical and sensitive approach for on-site environmental monitoring.
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