Optical Aptamer-Based Sensors for Detecting Plant Hormones

This paper reports a new chip equipped with aptamer-based sensors interfaced with a capillary microfluidics suitable for screening and detecting hormones in plant samples. The microfluidic capillary interface of the chip ensures the samples to be automatically delivered to the sensors on the chip even without any external pumps, making it potentially suitable for operation in the field or source-limited settings if a sample-preparation component is integrated on the same chip. The arrayed sensors can be functionalized with aptamers specific to different plant hormones, hence this chip can screen and identifythe hormones from unknown samples. Since currently only an abscisic acid (ABA) aptamer and a salicylic acid (SA) aptamer are identified and available, as a technical demonstration, in this research, the sensors are only functionalized with ABA aptamer and SA aptamer to evaluate the performance of this chip. Using this chip, the detection of five plant hormones (ABA, SA, auxins, cytokinins, gibberellins) in buffer and plant extracts has been demonstrated with very good specificity and high sensitivity. And the sensors can detect both ABA and SA as low as 0.1 μM. All these measurements require only 1 μl samples and could be carried out within less than 30 min. Furthermore, the sensor reusability has been evaluated by regenerating the sensors. Given its minimal external equipment operational requirement, this chip offers a suitable platform for rapid, sensitive, and inexpensive screening and identification of plant hormones in raw plant samples.