The classical chemistry of sodium thiosulfate was applied to synthesize luminescent Sdots where elemental sulfur produced in situ was etched with NaOH. This method notably reduces the synthesis time of Sdots in comparison to the previously reported etching technique of bulk sulfur. The assynthesized Sdots exhibited excitation dependent photoluminescence with a QY of 2.5%, photostabality under UV light irradiation, excellent dispersibility in aqueous medium, and also the stability even after several weeks. Notably, no emission was observed due to the oxidation of PEG-400 during the course of reaction. The Sdots was then employed as a dual function probe for the sensing of metal ions. Using fluorimetric method, Sdots showed preferential selectivity toward the Co 2+ metal ions. However, a single probe Sdots can colorimetrically distinguish multiple metal ions such as Co 2+ , Cr 6+ , and Pb 2+ by displaying color change on the immediate addition of analytes. Furthermore, the color change of Sdots is demonstrated with the help of hue images and hue spectra (or histogram) that will help in the development of Sdots based portable device. The present study contributes to the further advancement of this emerging field as a promising single-element nanomaterial an alternative to luminescent metallic nanomaterials.

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A mechanochemical synthesis of luminescent sulfur quantum dots (Sdots) is demonstrated for the first time to reduce the synthesis reaction time. Structural characterization using X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectroscopy confirmed the formation of Sdots. The present method produced Sdots through a short-chain polymerization of sulfur and features an excitation-dependent photoluminescence with a quantum yield of 4.8%, high photostability, excellent hydrophilicity, and low toxicity. Further, Sdots were seen to cause a low toxicity in both normal and cancer cells, which makes this a promising candidate for bioimaging and biolabeling.

Herein, different surface charged carbon dots (Cdots) were synthesized by using diethylene glycol as a carbon source with various amine containing surface passivating agents. The synthesis method is very simple and fast microwave oven-based, that results in almost similar sized positive, negative and uncharged fluorescent Cdots which has been confirmed by zeta potential analysis in our case. The formation of Cdots was confirmed by characterization using fluorescence spectroscopy, transmission electron microscopy, XRD, FT-IR, and XPS spectroscopy. To find out relative bactericidal activity of these Cdots, green fluorescence protein expressing recombinant E. coli bacteria were taken as a model system. Time-dependent bacterial growth and FACS study demonstrated that both uncharged Cdots and positively charged Cdots were showing better bactericidal activity as compared to negative charged Cdots. The Cdots caused elevation of reactive oxygen species level, which is possibly leading to bacterial cell death.

Herein, we report aggregation induced red shifted emissions in N,S-doped chiral carbon dots for moisture sensing in common organic solvents and commercial products.

Aggregation-induced emission (AIE) has unlocked a completely new research area corresponding to application potentials of luminescent materials. Notably, carbon dots (Cdots) are emerging as well-recognized alternative to organic dyes because of their fascinating fluorescence properties. They exhibit improved emission when aggregated due to the changes in solvent polarity, higher concentration, externally added chemical species. Herein, a review on the AIE property is demonstrated with a substantial emphasis on Cdot optical property. Mechanistic overview along with application potentials of the same in sensing, optoelectronic devices, fingerprints recognition and solar concentrators are highlighted. Finally, a summary corresponding to recent developments and future prospects have been discussed.

We have demonstrated a rapid and facile synthetic method to prepare N-doped Cdots that has excitation independent-emission in yellow-orange region. The Cdots showed solvatochromic behavior in different solvents due to change in solvent polarity illustrating n → π* transition (edge band).

The need for antimicrobial or antibacterial fabric has increased exponentially in recent past years, especially after the outbreak of the SARS-CoV-2 pandemic. Several studies have been conducted, and the primary focus is the development of simple, automated, performance efficient and cost-efficient fabric for disposable and frequent-use items such as personal protective materials. In this regard, we have explored the light-driven antibacterial activity of water-soluble Sdots for the first time. Sdots are a new class of non-metallic quantum dots of the nanosulfur family having a polymeric sulfur core. These Sdots exhibited excellent antibacterial activity by generating reactive oxygen species under sunlight or visible light. Under 6 h of sunlight irradiation, it was observed that >90% of the bacterial growth was inhibited in the presence of Sdots. Furthermore, low toxic Sdots were employed to develop antibacterial fabric for efficiently cleaning the bacterial infection. The prominent zone of inhibition of up to 9 mm was observed post 12 h incubation of Sdots treated fabric with E. coli in the presence of visible light. Furthermore, the SEM study confirmed the bactericidal effect of these Sdots-treated fabrics. Moreover, this study might help explore the photocatalytic disinfection application of Sdots in diverse locations of interest, Sdots-based photodynamic antimicrobial chemotherapy application, and provide an opportunity to develop Sdots as a visible light photocatalyst for organic transformations and other promising applications.