Department of Biological & Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA.
Agricultural & Biological Engineering, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
Sensors (Basel). 2020 Oct 12;20(20):5773. doi: 10.3390/s20205773.
Irrigation water is a primary source of fresh produce contamination by bacteria during the preharvest, particularly in hydroponic systems where the control of pests and pathogens is a major challenge. In this work, we demonstrate the development of a biosensor using platinum interdigitated microelectrodes (Pt-IME). The sensor is incorporated into a particle/sediment trap for the real-time analysis of irrigation water in a hydroponic lettuce system. We demonstrate the application of this system using a smartphone-based potentiostat for rapid on-site analysis of water quality. A detailed characterization of the electrochemical behavior was conducted in the presence/absence of DNA and spp., which was followed by calibration in various solutions with and without flow. In flow conditions (100 mL samples), the aptasensor had a sensitivity of 3.37 ± 0.21 k log-CFU mL, and the LOD was 48 ± 12 CFU mL with a linear range of 10 to 10 CFU mL. In stagnant solution with no flow, the aptasensor performance was significantly improved in buffer, vegetable broth, and hydroponic media. Sensor hysteresis ranged from 2 to 16% after rinsing in a strong basic solution (direct reuse) and was insignificant after removing the aptamer via washing in Piranha solution (reuse after adsorption with fresh aptamer). This is the first demonstration of an aptasensor used to monitor microbial water quality for hydroponic lettuce in real time using a smartphone-based acquisition system for volumes that conform with the regulatory standards. The aptasensor demonstrated a recovery of 90% and may be reused a limited number of times with minor washing steps.
灌溉水是新鲜农产品在收获前受到细菌污染的主要源头，尤其是在水培系统中，虫害和病原体的控制是主要挑战。在这项工作中，我们展示了一种使用铂叉指微电极（Pt-IME）的生物传感器的开发。该传感器被整合到一个颗粒/沉积物陷阱中，用于实时分析水培生菜系统中的灌溉水。我们展示了使用基于智能手机的电化学工作站对该系统的应用，用于快速现场分析水质。在存在/不存在 DNA 和 spp.的情况下，对电化学行为进行了详细的特征描述，随后在有无流动的各种溶液中进行了校准。在流动条件（100 毫升样品）下，适配体传感器的灵敏度为 3.37 ± 0.21 k log-CFU mL，LOD 为 48 ± 12 CFU mL，线性范围为 10 到 10 CFU mL。在无流动的静止溶液中，缓冲液、蔬菜肉汤和水培介质中的适配体传感器性能得到了显著改善。在强碱性溶液中冲洗后（直接重复使用），传感器的滞后范围为 2-16%，而在通过在 Piranha 溶液中清洗去除适配体后（用新鲜适配体吸附后重复使用），则没有滞后。这是首次使用基于智能手机的采集系统，实时监测水培生菜的微生物水质，该系统体积符合监管标准，使用适配体传感器进行监测的演示。适配体传感器的回收率为 90%，经过少量清洗步骤后可以有限次数地重复使用。
