Nano-biochemical sensors for trace uranyl detection: Advances in Recognition elements and signal output strategies

Abstract

Uranium is a strategic resource for the nuclear industry, but its mining and utilization can cause environmental contamination. In aquatic environments, the highly stable and soluble uranyl ion (UO22+) exhibits both chemical toxicity and radioactivity, posing serious threats to ecosystems and human health. Accordingly, rapid, highly sensitive, and anti-interference detection of UO22+ has become a major focus in nano-biochemical sensing. This review systematically summarizes recent advances in specific recognition strategies and signal transduction mechanisms for UO22+. From the perspective of molecular recognition, we outline the design of diverse recognition elements, including traditional coordination-based small-molecule ligands (N-donor, O-donor, S/O-mixed, and multidentate amidoxime ligands), lanthanide metal nodes, and synergistic coordination-hydrogen-bonding motifs, together with biomacromolecular and biomimetic strategies such as aptamers and molecular/ion imprinting. We further discuss how chemical recognition events are converted into readable optical or electrical outputs in UO22+ sensing systems. Representative mechanisms include nanozyme activity modulation, target-induced complex formation, and fluorescence, photoelectrochemical, or electrochemical signaling based on fluorescence resonance energy transfer, aggregation-induced emission, inner filter effect, charge transfer, and ion exchange. Finally, we highlight key challenges in applying current UO22+ biochemical sensors to complex water matrices and discuss future directions, including highly selective anti-interference materials, multimodal sensing platforms, and portable intelligent devices. This review aims to provide a theoretical basis and design guidance for next-generation high-performance platforms for trace uranium pollution monitoring.