Biomass-derived Carbon dots and their coated surface as a potential antimicrobial agent

Carbon dots (CDs) with an average diameter of 6.3 nm were synthesized from the medicinal seed extract of Syzygium cumini L. using one-pot hydrothermal synthesis. The prepared CDs exhibited excitation-dependent emission characteristics with photoluminescence (PL) emission maxima at an excitation of 340 nm. The CDs at 500 µg/mL displayed antimicrobial activities against four common pathogens. Both Staphylococcus aureus and S. epidermidis were completely eradicated by CDs within 12 h, compared to 24 h for Escherichia coli and Klebsiella pneumonia. The release of various oxygen species (ROS) was postulated to play a critical role in bacterial eradication. The CDs decorated on cotton fabric by ultrasonication also displayed good antibacterial activities against the above bacteria. The finding opens a plausible use of CDs in biomedical textiles with potent antimicrobial properties against both Gram-negative and Gram-positive bacteria.RP/CPS/2022/007; Tomas Bata University in Zlin, TBU: IGA/CPS/2022/002Ministry of Education, Youth and Sports of the Czech Republic Program-DKRVO [RP/CPS/2022/007]; Internal Grant Agency of Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2022/002

Grape seed extract assisted synthesis of dual-functional anatase TiO₂ decorated reduced graphene oxide composite for supercapacitor electrode material and visible light photocatalytic degradation of bromophenol blue dye

The grape extract is a potential natural reducing agent because of its high phenolic content. The extracts of seeds, skin, and pulp of grape were prepared by digestion, grinding, and soxhlet methods and used for reducing graphene oxide (GO). The reduced GO made using the soxhlet extract of grape seed (GRGO) was hydrothermally treated with titanium dioxide (TiO2) for the synthesis of GRGO-TiO2 nanocomposite. The X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-vis, photoluminescence, and Raman spectra studies further confirmed the formation of GRGO and the GRGO-TiO2 hybrid. Scanning electron microscope and transmission electron microscope studies showed the decoration of spherical TiO2 particles ( 400 nm), GRGO-TiO2 showed ∼30% higher photo-oxidation of the bromophenol blue (BPB) dye than TiO2. Also, GRGO-TiO2 decreased the total organic carbon content of BPB from 92 to 18 ppm. Overall, the soxhlet extract of grape seed was found to be a cost-effective reducing agent for the preparation of GRGO, which is a suitable material to be used in supercapacitors and photocatalysis.Published versionThe authors are grateful to the Department of Science and Technology, Government of India, for its financial support. S. Ramasundaram and B. Kim acknowledge the Korea Ministry of Education, Science, and Technology for its financial support via the National Research Foundation of Korea for the priority Research Centers Program (NRF-2018R1A6A1A03025526) and in part by the Sabbatical Research Promotion Funding from the Korea University of Technology and Education