Design of “Turn-Off” Fluorescent Nanoprobe for Highly Sensitive Detection of Uric Acid using Green Synthesized Nitrogen-Doped Graphene Quantum Dots

Green synthesized graphene quantum dots (GQD) have been doped with nitrogen in an attempt to boost their optical characteristics and application sectors. In the present investigation, the blue luminescent nitrogen-doped GQDs (N-GQDs) were synthesized by single-step hydrothermal synthesis using tamarind shell powder as a precursor. The particle size and zeta potential of N-GQDs were found to be 11.40 nm and be –35.53 mV, respectively. A quantum yield as high as 23.78 % was accomplished at an excitation wavelength of 330 nm at neutral pH. It gets quenched sensitively in the existence of uric acid (UA) combining static quenching, electron transfer, and an inner filter effect mechanism. A linear range was obtained for UA from 10 µM to 100 µM, with a limit of detection (LOD) of 401.72 ± 0.04 pM. Additionally, the N-GQDs were selective toward UA in presence of metal ions and biomolecules that indicated its impending use to monitor UA in clinical samples. In conclusion, this work demonstrates that the N-GQDs as a sensing probe for UA recognition with notable advantages including socioeconomic, simple, and less time-consuming methods as compared to other methods. In the future, it can be potentially explored as a biosensor for UA detection in clinical samples

Green Synthesis of Silver Nanoparticles: An Eco-Friendly Approach

Eco-friendly synthesis of nanoparticles is an upcoming discipline of nanoscience. Green synthesis of Ag NPs has gained immense importance and much awareness in developed nations. Fascinatingly, such an environmental friendly synthesis of Ag NPs gives a green chemistry-based non-toxic and economical route to nanotechnology. This review article gives insight into the bioinspired synthesis of Ag NPs and mechanisms involved in the synthesis of Ag NPs. In this review, we have summarized the scientific reports in the eco-friendly synthesis arena of Ag NPs and their applications in the biomedical field. Especially, we have focused on plant materials, fungi, algae, and bacterial potential towards the eco-friendly synthesis of Ag NPs. For future perception, there is a need for in silico and in vitro, in vivo research to authenticate the outcomes

Agro-Industrial Waste-Mediated Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity

The development of immaculate etiquette for the green and rapid synthesis of Ag NPs with a natural reducing agent is the spearhead of the expanding field of nanotechnology. Different scientific fraternity with novel natural reducing agents has been contributing numerous strategies daily. Though there is a submerging of many natural reducing agents, still there are plenty of natural precursors remained to be explored. In this research, we fruitfully attempted the synthesis of silver nanoparticles using agro-food industrial waste Tamarindus indica shell-husk extract (TSE) as a natural reducing agent. The prepared silver nanoparticles and their stability in different pH were investigated using ultraviolet-visible spectroscopic analysis. Morphological characters were examined using scanning electron microscope (SEM) and transmission electron microscopy (TEM) analysis. The structural and elemental compositions were depicted by Fourier-transform infrared spectroscopy (FTIR) and energy-dispersive X-ray (EDX) analysis, respectively. Moreover, we emphasized on the molecular mechanism involving in the TSE mediated synthesis of Ag NPs. The inherent antimicrobial activity was investigated using agar plate method against both gram-positive and gram-negative species with gentamycin as a control standard for comparison

Graphene Quantum Dots Incorporated UiO-66-NH2 Based Fluorescent Nanocomposite for Highly Sensitive Detection of Quercetin

Quercetin can help with a variety of health problems. Most methods for measuring quercetin in biological fluids are characterized by low sensitivity and selectivity. The employment of metal–organic frameworks in sensor applications with carbon-based materials ushers in a new era. In this study, blue fluorescent graphene quantum dots (GQDs) embedded in a UiO-66-NH2 metal–organic framework-based nanoprobe (GQDs@UiO-66-NH2) were constructed for quercetin sensing. Initially, maize husk was used to produce blue fluorescent GQDs, whereas zirconium tetrachloride and 2-aminoterephthalic acid were used to synthesize extremely luminous UiO-66-NH2. The addition of quercetin to GQDs@UiO-66-NH2 leads to fluorescence dampening due to the adsorption potential of UiO-66-NH2. The complexation of zirconium ions with the 3-OH and 4-C＝O functionalities of quercetin resulted in fluorescence quenching. The sensor has a linear concentration range and limit of detection for quercetin of 50–500 and 2.82 ng/mL, respectively. The nanoprobe’s usefulness for quercetin detection was then validated by a selectivity investigation in the presence of interfering chemicals. Furthermore, the percentage relative standard deviations were 4.20% and 2.90%, respectively, indicating great stability and repeatability. Fluorescence “Turn-On–Off” nanoprobes provide a simple, quick, sensitive, and selective method for monitoring quercetin

Fabrication of N-Doped Graphene@TiO2 Nanocomposites for Its Adsorption and Absorbing Performance with Facile Recycling

The present work aims to synthesize nitrogen-doped reduced graphene oxide-titanium dioxide nanocomposite (N-rGO@TiO2) using a simple, eco-friendly method and its applications in spectroscopic detection of heavy metal ions such as lead (Pb2+), mercury (Hg2+), and chromium-VI [Cr(VI)] in potable water. Initially, TiO2 nanoparticles loaded N doped rGO sheets were fabricated by an ecological method using Gossypium hirsutum (cotton) seeds extract as a green reducing agent. Then, the N-rGO@TiO2 nanocomposites were subjected for characterizations such as spectroscopic techniques, particle size analysis, zeta potential analysis, and spectroscopic sensing. Notably, the results of this study confirmed that N-rGO@TiO2 exhibited countless stupendous features in terms of sensing of an analyte. Briefly, the UV-visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy confirmed the successful synthesis of N-rGO@TiO2. The SEM images showed the wrinkled, folded, and cross-linked network structures that confirmed the surface modification and nitrogen doping in the rGO sheet and synthesis of N-rGO@TiO2. The EDAX study confirmed the elemental composition of the N-rGO@TiO2 nanocomposite. Finally, due to the larger surface area, porous nature, high electron mobility, etc. the N-rGO@TiO2 probe provides the lower detection limit for Pb2+, Hg2+, and Cr (VI) as low as 50 nM, 15 μM, and 25 nM, respectively. Concisely, our study affirms the admirable sensitivity of N-rGO@TiO2 nanocomposite to the Pb2+, Hg2+, and Cr (VI) in potable water can provide better environmental remediation