Alendronate-Modified Polydiacetylene (PDA) Dual-Mode Sensor for the Selective Detection of Lead(II) Ions up to the nM Level in Solutions and Agarose Films

Lead contamination in humans has been linked to several health risks, such as anemia, cardiovascular problems, renal failure, and irreversible neurological damage. This necessitates the development of efficient sensing tools for low-level detection of lead contamination in water. In this study, we report the design and development of polydiacetylenes (PDAs)-based highly sensitive dual-output sensor for the detection of lead ions in solution and solid phase. Specifically, 10,12-pentacosadiynic acid (PCDA)-derived vesicles were surface modified with alendronate units (PCDA-Alen) to enable specific recognition of lead ions in the presence of other metal ions and possible interfering species. Upon UV irradiation (254 nm), PCDA-Alen displayed a characteristic blue color that, on interaction with lead ions, exhibited a characteristic color transition from blue to red accompanied by a gradual increase in fluorescence emission at λmax 642 nm. PCDA-Alen was indifferent to a variety of cations or anions and displayed detection limits of 16.8 and 3.1 ppb toward lead in UV–vis and fluorescence spectroscopy, respectively, and thus acts as a dual-output sensor. The real sample studies by spiking Pb2+ in samples collected from various natural water bodies demonstrated excellent recovery. PCDA-Alen vesicles immobilized on agarose matrix enabled naked-eye detection of lead ions above 0.5 μM in the solid phase, showcasing exceptional lab-on-film-based detection capabilities, thereby expanding their potential for real-world applications in the detection of lead ions in environmental and biological samples.