A smartphone-assisted chromogenic and fluorogenic dual-channel sensor for specific determination of toxic Pb2+ ions with multifaceted applications

Abstract

Heavy metal pollutants, such as Pb²⁺ ions, pose a substantial hazard to human health and ecosystems, and it was of great significance to develop cost-effective and portable techniques for online and visual detection of Pb²⁺. Herein, we fabricated a novel chromogenic and fluorogenic dual-channel sensor NQA through a Schiff base reaction involving a dicyanoisophorone derivative and isoniazid, enabling effective detection of Pb²⁺ ions. Upon complexation with Pb²⁺ ions at a 1:1 M ratio, the fluorescence intensity of NQA exhibited a remarkable enhancement. The naked-eye colorimetric detection utilizing NQA demonstrated a distinct color change to specific Pb²⁺ ions concentration from yellow to light pink. Based on this principle, a smartphone-assisted sensing platform was developed for visual and high-quality identification of Pb²⁺ in real samples. The UV binding constant for Pb²⁺ ions was determined to be 1.84 × 10⁵ M⁻¹, with a detection limit of 0.38 μM. Furthermore, the versatility of NQA extended to applications in naked-eye test paper experiments, the detection of Pb²⁺ ions in real water samples and living cells, showcasing its potential for environmental and biological monitoring.