Palma-Roldán Javier, Román-Pizarro Vanesa, García-Granados Miguel Ángel, Fernández-Romero Juan Manuel, Écija-Arenas Ángela
Departamento de Química Analítica, Instituto Químico Para La Energía y El Medioambiente (IQUEMA), Universidad de Córdoba, Edificio Anexo "Marie Curie", Campus de Rabanales, 14071, Córdoba, Spain.
Mikrochim Acta. 2025 Jul 31;192(8):545. doi: 10.1007/s00604-025-07405-5.
A microfluidic analytical system based on magnetically retained nanomaterials has been developed using fluorometric detection. This system utilizes magnetic gold nanoclusters (AuMNCs) to determine total tetracyclines using three of them as model-chlortetracycline (CTC), doxycycline (DC), and oxytetracycline (OTC)-in water samples by monitoring the change in the luminescent signal produced upon interaction. AuMNCs were synthesized by adding preformed magnetic nanoparticles (MNPs) to bovine serum albumin (BSA) as stabilizer and ascorbic acid as a reducing agent. Their magnetic properties enable their retention in the reaction/detection zone of the microfluidic system. The reactor was integrated into the optical pathway of a conventional spectrofluorometer with a 3D-printed device to align the excitation beam with the microchannel. The instrumental signal was obtained at a 22.5° angle from the excitation beam. Key parameters were studied, including pH (optimal at 11 with carbonate buffer), flow rate (40 µL·min⁻), and AuMNCs injection volume (10 µL). The analytical signal was based on the fluorescence intensity ratio between the emission of the AuMNCs (650 nm) and the AuMNCs-tetracycline complexes (425 or 510 nm). Limits of detection of 0.41 µmol·L⁻ for CTC, 0.70 µmol·L⁻ for DC, and 0.61 µmol·L⁻ for OTC, with relative standard deviations (RSD) below 6.2%, were achieved. Compared with non-retained AuMNCs, the magnetically retained system showed improved results. The system was applied to determine different tetracyclines in water samples, with recoveries in spiked river water samples from 86 to 111%. This approach offers a simple, label-free, and versatile alternative with potential for future development into multi-analyte sensing platforms or applications in complex matrices.
一种基于磁性保留纳米材料的微流控分析系统已通过荧光检测技术得以开发。该系统利用磁性金纳米簇（AuMNCs）来测定水中的总四环素，以金霉素（CTC）、强力霉素（DC）和土霉素（OTC）这三种四环素作为模型，通过监测相互作用时产生的发光信号变化来实现。AuMNCs是通过将预先形成的磁性纳米颗粒（MNPs）添加到作为稳定剂的牛血清白蛋白（BSA）以及作为还原剂的抗坏血酸中合成的。其磁性特性使其能够保留在微流控系统的反应/检测区域。该反应器通过一个3D打印设备集成到传统荧光光谱仪的光路中，以使激发光束与微通道对齐。仪器信号是在与激发光束呈22.5°角处获得的。研究了关键参数，包括pH值（在碳酸盐缓冲液中11时最佳）、流速（40 μL·min⁻）和AuMNCs进样体积（10 μL）。分析信号基于AuMNCs（650 nm）发射与AuMNCs - 四环素复合物（425或510 nm）发射之间的荧光强度比。实现了对CTC的检测限为0.41 μmol·L⁻（相对标准偏差（RSD）低于6.2%），对DC为0.70 μmol·L⁻，对OTC为0.61 μmol·L⁻。与未保留的AuMNCs相比，磁性保留系统显示出更好的结果。该系统应用于测定水样中的不同四环素，加标河水样的回收率为86%至111%。这种方法提供了一种简单、无标记且通用的替代方案，具有未来发展成为多分析物传感平台或应用于复杂基质的潜力。
