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Carbon quantum dots (CQDs) are fluorescent nanoparticles with diverse applications in multiple fields. The optical and physical properties of CQDs are influenced by several factors, such as the synthesis method, surface passivation and particle size. This study explores how carbon concentration affects the properties of CQDs. The CQDs were synthesized through a carbonization process with carbon concentrations varying from 0.03 to 0.15 g/ml. The samples of CQDs were characterized by using high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectroscopy, zeta potential, dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). The results indicate that carbon concentration significantly impacts the optical properties and zeta potential of CQDs. Specifically, higher carbon concentrations result in increased fluorescence intensity and larger particle size. HRTEM images reveal that the average size of the CQDs is below 10 nm, consistent with DLS measurements. These findings suggest that carbon concentration can serve as a straightforward and effective parameter for tuning CQDs properties, with potential applications in bioimaging, sensing and optoelectronics. [ABSTRACT FROM AUTHOR]

The present study reports a novel technique to synthesise silica nanoparticles through modified sol-gel, ultrasonication, and hydrothermal routes. Physio-chemical and structural characterization was carried out using X-ray diffraction, high resolution scanning electron microscopy, energy dispersive spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, ultraviolet-visible, and photoluminescence spectroscopy. The particle size determination revealed the spherical structure of nanoparticles with an average diameter of 85 nm and between 90-170 nm through HRSEM and DLS respectively. Stretching and vibration bands confirming the presence of SiO2 were obtained in FTIR analysis. Spectra from UV-vis and PL spectroscopy were obtained at a maximum wavelength of 233 nm and 555 nm respectively. The anti-microbial effect of SiO2 nanoparticles against E. coli and S. aureus bacteria revealed the appreciable response which renders them for many biomedical applications like drug delivery. The cytotoxicity of SiO2 nanoparticles on human lung epithelial (A549) cell line revealed their non-toxic behavior. [ABSTRACT FROM AUTHOR]

The present work was conducted to biofabricate silver nanoparticles (AgNPs) in single step employing aqueous extract of Dregea volubilis flowers and to investigate its antioxidant, antidiabetic and antibacterial activities. The AgNPs were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectrometry, high resolution transmission electron microscopy (HRTEM) and zeta potential study. The biofabricated AgNPs showed potential antioxidant activity for scavenging DPPH radical (IC50, 40.45 ± 5.06 μg/mL), ABTS radical (IC50, 78.49 ± 1.41 μg/mL), total antioxidant capacity (148.83 ± 2.99 mg GAE/g) along with remarkable inhibitory effects on α-amylase (IC50, 10.62 ± 0.22 μg/mL) and α-glucosidase (IC50, 6.49 ± 0.03 μg/mL). The AgNPs showed notable antibacterial activity in terms of zone of inhibition (in mm) against Pseudomonas aeruginosa (10.67 ± 0.44), Escherichia coli (9.33 ± 0.44), Bacillus subtilis (14.67 ± 0.60) and Staphylococcus aureus (15.67 ± 0.60). [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been synthesized by modified Hummers' method and characterized by Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscopy. GO characterized using Fourier transform infrared spectra shows that the graphite powder is strongly oxidized by resilient oxidants and the oxygen atoms are present in form of functional groups such as COOH, O–H, C–O–C, and C = O, bonds. GO pellets were prepared to study its dielectric properties as a function of frequency. Dielectric permittivity and electrical conductivity of GO strongly depends upon the extent of temperature. [ABSTRACT FROM AUTHOR]