The electropolymerization and electrocatalytic properties of polymerized new fuchsin film modified electrodes

Basic Fuchsin Dye as the First Fluorophore for Optical Sensing of Morpholine in Fruits Crust and Urine Samples

In this work, basic fuchsin (BF) dyestuff was presented as the first optical sensor used for the spectrofluorimetric assessment of morpholine (MOR) where BF exhibits morpholine-sensing behavior. The developed fluorimetric avenue is sensitive, facile, selective, and validated for assaying the sensitizing influence of MOR on the BF fluorescence in an aprotic dioxane solvent. Parameters like solvents, BF concentration, order, and time of addition that influence the fluorescence intensity of the probing system were addressed. Optimizing the analytical methodology revealed a linear fluorescence sensitization within the addition of MOR in the two concentration ranges of 5 × 10-9 to 1.0 × 10-7 mol L-1 and 2.0 × 10-7 to 3 × 10-6 mol L-1. The limit of detection (LOD) and limit of quantification (LOQ) were estimated to be 2.0 × 10-9 mol L-1 (0.17 ng mL-1) and 6.66 × 10-9 mol L-1 (0.567 ng mL-1), respectively. High levels of accuracy and precision are achieved when assaying spiked MOR either in pure solutions or samples of fruit peel extract and human urine. Moreover, the green character and practicality/applicability of the method were evaluated by AGREE and BAGI metric tools. These merit outcomes provide insights into the development of fluorescent sensors for MOR detection using fluorescent dyes and meet the Food and Drug Administration's requirements for morpholine detection in real-life applications.

Ultrafast Excited State Relaxation Dynamics of New Fuchsine- a Triphenylmethane Derivative Dye

An all-inclusive investigation of the ultrafast excited state relaxation dynamics of a triphenylmethane derivative molecule, New Fuchsine (NF), using a combined approach of density functional theory (DFT), femtosecond transient absorption spectroscopy (fs-TAS), and photoluminescence spectroscopy is presented in this work. The DFT calculations confirmed the formation of twisted molecular structure in the excited state of NF in ethanol solution with bond rotation of ≈ 86⁰ . TAS measurements of NF solution exhibited ultrafast ground state-recovery pathway via a conical intersection confirming an ultrafast structural reorientation. On the contrary, TAS measurements of NF thin-film exhibited a longer excited-state lifetime suggesting a hindered molecular twisted state formed as an intermediate step. Photophysical kinetic models are proposed to globally fit the fs-TAS data establishing the twisted intramolecular charge transfer (TICT) state mediated ground state recovery for NF in solution and thin film, respectively. Temperature-dependent photoluminescence study of NF film provided a clear insight into the effect of rotational motion of phenyl rings in NF molecules over the TICT mediated emission.

One-step synthesis of functional pNR/rGO composite as a building block for enhanced ascorbic acid biosensing

An electrochemical sensor for ascorbic acid (AA) was prepared via an one-step electrochemical approach by reducing graphene oxide (rGO) and co-polymerizing neutral red (NR) and rGO to form a pNR/rGO hybrid film on the glassy carbon electrode (pNR/rGO-GCE). Structures and properties of the obtained pNR/rGO film were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and UV-vis techniques. A significant decrease of charge-transfer resistance (Rct) from over 20,000 Ω for pNR-GCE to 130 Ω for pNR/rGO-GCE was validated by electrochemical impedance spectroscopy (EIS) measurement. Particularly, electrochemical data revealed that pNR/rGO film could effectively enhance the electron transfer between AA and electrode, and thus reduce the overpotential of AA oxidation. Two linear regression areas with 0.05-0.75 mM and 0.9-24.9 mM, detection limit with 1.4 μM, and stability over 2 weeks were obtained. The coexisting distractions such as dopamine, uric acid and glucose were detected and eliminated. Moreover, the pNR/rGO-GCE gave the same determination results as that obtained with HPLC when measuring real samples, including vitamin C beverage and human serum.