Recent Advances in Fluorescent-Based Chemosensors for Lead(II) Detection: A Decade Review (2015–2025)

Lead contamination remains a pressing global challenge due to its severe toxicity and persistence in the environment. In recent years, fluorescent-based chemosensors have emerged as powerful tools for the rapid, selective, and sensitive detection of Pb²⁺ ions. This review provides a comprehensive analysis of the progress made between 2015 and 2025 in the development of fluorescent chemosensors for lead ion detection. The discussion focuses on six major classes of chemosensors: rhodamine-, coumarin-, thiophene-, quinoline-, thiosemicarbazone-, and triazole-based systems. For each category, design principles, sensing mechanisms, photophysical properties, and detection performance are systematically examined. The review also highlights challenges such as interference from competing metal ions, limitations in aqueous/biological environments, and the need for real-time detection platforms. The highest analytical sensitivity (lowest LODs) in this decade has been realized to have come from DNAzyme/amplification/aptamer platforms (pM to low-pM). Small-molecule chemosensors (rhodamine, naphthalene, coumarin, Schiff bases) commonly achieve nM to sub-nM LODs and report binding constants when the work focuses on coordination chemistry. Stoichiometries vary (1:1, 2:1, etc.). Selectivity remains a challenge in many studies because authors typically test against a panel of common metal ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Cu²⁺). Hg²⁺ and Cd²⁺ are recurring interfering ions for Pb²⁺ sensors; many papers explicitly benchmark against them. Finally, future perspectives are provided on integrating fluorescent chemosensors with nanomaterials, microfluidic devices, and portable sensing platforms to advance practical applications in environmental and biomedical monitoring.