Electrochemiluminescent pH sensor measured by the emission potential of TiO 2 nanocrystals and its biosensing application

A Sensitive Electrochemiluminescence Urea Sensor for Dynamic Monitoring of Urea Transport in Living Cells

A multiple signal-amplified electrochemiluminescence (ECL) urea sensor was designed based on a self-enhanced probe and SiO₂ photonic crystals for dynamic tracking of urea transmembrane transport. The self-enhanced probe (AuNR@Ru-LA) prepared by loading polyethyleneimine (PEI), lactobionic acid (LA), and Ru(dcbpy)₃²⁺ on gold nanorods (AuNRs) generated an initial ECL signal, and then the intensity was multiple-amplified by the enhanced light-scattering effect of SiO₂ photonic crystals and the co-reaction with urea. The as-prepared sensor exhibited excellent performance for the detection of urea in the range of 1.0 × 10^-10 to 1.0 × 10^-4 M with a detection limit of 8.8 × 10^-11 M at (3σ)/S. The AuNR@Ru-LA probes were labeled on HepG2 cells to construct a cytosensor with a detection range of 1.0 × 10³ to 2.0 × 10⁶ cells mL^-1. In addition, the dynamic changes of the extracellular urea concentration were tracked by monitoring the ECL signal of the cytosensor to study urea transmembrane transport. The developed strategy realized the amplification of multiple ECL signals and the tracking of urea transmembrane transport, which provided a novel dynamic detection method for small biomolecules.

Enhanced electrochemiluminescence of Au–Ag bimetallic nanocluster@CNTs–TiO2 nanocomposite and its use in ultra-sensitive immunosensing for CEA

Highly efficient electrochemiluminescence (ECL) of novel Au–Ag bimetallic nanocluster@CNTs–TiO₂ nanocomposites (Au–Ag NCs@CNTs–TiO₂ NPs) with a unique “pearl necklace” structure is realized and applied as ECL immunosensor for cancer embryo antigen (CEA).

Structural and spectroscopic study of Ho3+ -doped nanotitania host prepared using a sol-gel technique

Holmium (Ho³⁺ )-doped TiO₂ solid laser active materials with different concentrations (1, 3, 5, and 7 wt%) of Ho³⁺ ions were prepared using a sol-gel method. A structural study of the samples using X-ray diffraction (XRD) revealed the anatase phase of pure and doped TiO₂ calcined at 500°C, which is confirmed by (101), (004), (200), (105), (211), (204), (116), (220) and (215) diffraction peaks. XRD analysis showen a deformation along the c-axis of the anatase lattice constant with doping, and a random change in the grain size of the doped titania with respect to pure samples. The presence of the titania bonds (Ti-O-Ti) and (Ti-O) of pure and Ho³⁺ -doped samples were confirmed from the FTIR spectroscopy study of the samples. In addition, it was noted that bands around 1338, and 1339 cm^-1 belonging to 3, 5, and 7 wt% dopant concentrations, while no band for 1 wt% was observed. UV-Vis spectrophotometer and spectrofluorophotometer techniques were used to study the optical and spectroscopic characterizations of these samples. It was found that various fluorescence peaks for Ho³⁺ ions were observed in the UV-vis region under different pump wavelengths. This is a good indication of suitability of the material to be employed as a laser active medium.

An ultrasensitive electrochemiluminescent sensor based on a pencil graphite electrode modified with CdS nanorods for detection of chlorogenic acid in honeysuckle

In this paper, a novel and ultrasensitive electrochemiluminescent sensor employing a solvothermal-synthesized CdS nanorod-modified pencil graphite electrode (CdS/PGE) for the determination of chlorogenic acid (CA) is fabricated. In the first step, the PGE surface is modified using CdS nanorods. In the next step, the developed electrode is used to detect CA using a electrochemiluminescent (ECL) technique, in which potassium persulfate (K₂ S₂ O₈ ) served as a co-reactant. The possible ECL mechanism is investigated, and the influences of pH and cyclic voltammetric scanning rate on the signal response are studied. The ECL intensity decreases quantitatively in relation to the concentration of the target molecule. Under optimized conditions, the linear correlation between the quenched ECL intensity and the logarithm of CA concentration is observed in the range from 2 × 10^-9 to 8 × 10^-7  mol L^-1 with a limit of detection of 1 × 10^-9  mol L^-1 . This proposed method is applied to the analysis of CA in honeysuckle flower, giving recoveries of 99-107%. The experimental results demonstrate that this ECL sensor shows good stability and reproducibility.