A novel electrochemical sensor with a dual-template molecular imprinting technology was fabricated for the simultaneous detection of paracetamol (PAR) and isoniazid (INZ). The sensor was constructed using nitrogen and sulfur co-doped molybdenum carbide (N, S@Mo₂C) and a thin layer of electro-polymerized methylene blue was applied onto the surface of the N, S@Mo₂C. The electrochemical sensor demonstrated remarkable analytical efficiency for the concurrent PAR and INZ quantification under optimal circumstances. The system achieved an exceptionally low limit of detection (S/N = 3) of  3.7 nM for PAR, with a concentration range  of  0.013 and 140 µM.  A LOD of 7.6 nM was attained for INZ, with a linear range  between 0.025 and 140 µM. Furthermore, the platform’s selectivity was evaluated using differential pulse voltammetry  (DPV). The designed platform successfully detected PAR and INZ in authentic samples with recoveries varying between 98.3% and 104.9%. The relative standard deviations (RSD) for these measurements ranged from 2.7 to 4.0%, demonstrating that the proposed sensor is extremely stable, repeatable, and reproducible. These promising results suggest that the sensor holds potential for the detection of various (bio) molecules, paving the way for future applications in sensing fields.

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Accurate determination of glutathione (GSH) levels in biological fluids and food supplements is paramount. To address this need, we developed a near-infrared (NIR) fluorescent probe with high sensitivity and selectivity for GSH detection. This probe comprises thioctic acid-functionalized silver and gold nanoclusters (ThA@Ag/Au NCs), emitting red light at 720 nm upon excitation at 310 nm. In the presence of Fe³⁺ ions, which form complexes with ThA, the fluorescence of ThA@Ag/Au NCs is quenched due to aggregation. However, upon addition of GSH, a potent chelator for Fe³⁺, the fluorescence of the probe is restored, leading to enhanced emission. Under optimized conditions, the fluorescence response (F/F°) exhibits a linear relationship with increasing GSH concentration within the range of 0.03–95 µM, achieving a limit of detection (LOD) of 9.0 nM. This designed scheme demonstrates excellent selectivity, sensitivity, and accuracy for GSH detection. Furthermore, the NIR fluorescent probe effectively estimated GSH levels in various matrices, including capsules, serum, urine, and saliva samples, yielding recoveries % ranging from 97.2 % to 103.2 %, with RSD % below 4.34 %. Due to its NIR properties, this fluorescent probe holds promise for diagnosing various diseases and potential in vivo applications.

Graphical abstract

Terbium and nitrogen co-doped carbon dots (Tb@N-CDs), combined with α-lipoic acid-functionalized copper nanoclusters (LA@CuNCs), were proposed for the ratiometric detection of quinolone (QA) antibiotics. In this system, Tb@N-CDs facilitate the aggregation of LA@CuNCs, enhancing its fluorescence emission at 670 nm via aggregation-induced emission enhancement (AIEE). Meanwhile, the fluorescence emission of Tb@N-CDs at 460 nm diminishes due to Förster resonance energy transfer (FRET). Upon the introduction of QA, the binding between Tb³⁺ ions and N-CDs weakens, disrupting both AIEE and FRET processes. This disruption results in a reduction in fluorescence emission at 670 nm and a concurrent increase at 460 nm. The fluorescence response ratio (F₄₆₀/F₆₇₀) increases with higher concentrations of ciprofloxacin (CFX), demonstrating a linear range from 0.008 to 120 μmol L⁻¹ and LOD of 1.6 nmol L⁻¹. The method successfully detected CFX in milk and urine samples, achieving recoveries between 97.7 % and 103.8 %, RSD of less than 3.79 %.