SRM University

About: SRM University is a education organization based out in Chennai, India. It is known for research contribution in the topics: Computer science & Population. The organization has 10787 authors who have published 11704 publications receiving 103767 citations. The organization is also known as: Sri Ramaswamy Memorial University.

Green synthesis of fluorescent carbon dots from Borassus flabellifer flowers for label-free highly selective and sensitive detection of Fe3+ ions

Abstract: Utilization of biomass as a renewable and sustainable resource has attracted much attention around the world. For the first time, a new and green method has been developed to synthesize fluorescent carbon dots (CDs) using flowers obtained from Borassus flabellifer (male tree) by thermal pyrolysis. The synthesized CDs were comprehensively characterized by X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy, zeta potential measurements, UV-Vis spectroscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. These studies confirmed that the as-synthesized CDs were functionalized with the (–OH), (C–H), (C–O–C) and (CO) groups. TEM analysis revealed that the particle sizes of the CDs were in the 3 to 8 ± 1 nm range. Upon increasing the excitation wavelength from 300 to 400 nm, the emission spectrum shifted from 300 to 403 nm. Furthermore, the interaction between the CDs and metal ions was evaluated by testing with various metal ions and the fluorescence intensity of the CDs was measured under 320 nm excitation. Excellent fluorescence quenching was observed only for Fe3+ ions compared to other metal ions such as Zn2+, Pb2+, Ni2+, Fe2+, Ca2+, Cu2+, Cr3+, Co2+ and Hg2+. The fluorescence intensity decreased after each addition of Fe3+ ions. The CDs were an efficient probe for detection of Fe3+ ions from 0 to 30 nM with a detection limit of 10 nM.

Fluorometric determination of lead(II) and mercury(II) based on their interaction with a complex formed between graphene oxide and a DNAzyme

Abstract: The authors have designed a DNAzyme where graphene oxide (GO) interacts with the ssDNA stem loop region. The DNAzyme strand and substrate strand are hybridized and bind to the surface of GO which act as a signal reporter, while GO act as a strong quencher. The presence of Pb(II) ion disturbs the GO-DNAzyme complex and causes internal cleavage of the DNAzyme complex. On addition of Thioflavin T (ThT) as a quadruplex inducer, fluorescence intensity (best measured at excitation/emission peaks of 425/490 nm) is strongly enhanced. Subsequent addition of Hg(II) to ThT/G-quadruplex complex decreases fluorescence because the G-quadruplex is unwinding to form a T-Hg(II)-T dsDNA system. Therefore, the change in fluorescence intensity of ThT is directly correlated to the concentration of Pb(II) and Hg(II). As a result, the assay is highly selective and sensitive. The limits of detection are 96 pM for Pb(II) and 356 pM for Hg(II). Moreover, the method was applied to the detection of the two ions in spiked real samples and gave satisfactory results.