Fast and Reliable Electronic Assay of a Xylella fastidiosa Single Bacterium in Infected Plants Sap

Abstract

Pathogens ultra-sensitive detection is vital for early diagnosis and provision of restraining actions and/or treatments. Among plant pathogens, Xylella fastidiosa is among the most threatening as it can infect hundreds of plant species worldwide with consequences on agriculture and the environment. An electrolyte-gated transistor is here demonstrated to detect X. fastidiosa at a limit-of-quantification (LOQ) of 2 ± 1 bacteria in 0.1 mL (20 colony-forming-unit per mL). The assay is carried out with a millimeter-wide gate functionalized with Xylella-capturing antibodies directly in saps recovered from naturally infected plants. The proposed platform is benchmarked against the quantitave polymerase chain reaction (qPCR) gold standard, whose LOQ turns out to be at least one order of magnitude higher. Furthermore, the assay selectivity is proven against the Paraburkholderia phytofirmans bacterium (negative-control experiment). The proposed label-free, fast (30 min), and precise (false-negatives, false-positives below 1%) electronic assay, lays the ground for an ultra-high performing immunometric point-of-care platform potentially enabling large-scale screening of asymptomatic plants.

Single Molecule with a Large Transistor – SiMoT cytokine IL‐6 Detection Benchmarked against a Chemiluminescent Ultrasensitive Immunoassay Array

“…This accounts for the occurrence of a few binding events, as described in detail elsewhere. [ 22 ] The assay noise level is given from the negative control experiment, resulting in (Δ I / I 0 ) = 0.03 ± 0.02. The LOD level, taken as the concentration corresponding to the noise average level plus three times its standard deviation, [ 26 ] is as low as 20 z m (2 × 10 −20 m ).…”

“…The transfer characteristics are analyzed by taking into account the relative shift of the measured current (I), compared to the baseline (I 0 ), namely (ΔI/I 0 ) = [(I − I 0 )/I 0 ], at the maximum transconductance, and this was taken as the SiMoT response. [15,17,22] Also, as validation methodology for the assay, the I D current recorded with the bare gold reference gate were monitored for the whole sensing assay, and these variation in the current relative shift remained below 5%. In Figure 3A the dose-response curves of the (ΔI/I 0 ) SiMoT assay for both the sensing (black squares) and the negative control (red circles) experiments carried out in IL-6 spiked PBS solutions are reported.…”

“…IgG, IgM, HIV-p24, and CRP), [12,[14][15][16][17] and genomic markers [18][19][20] also in both buffered solutions and real serum at the physical limit. Moreover, the covid virus [21] and Xylella fastidiosa bacterium [22] have been detected at the single entity level with such technology. Those studies pave the way toward developing ultra-sensitive, fast, highly reliable, and low-cost diagnostic systems for diagnosing diseases like tumors, viral and bacterial infections early.…”

Organic Bioelectronics Development in Italy: A Review

“…The use of electrochemical devices, and in particular OECTs, has generated an improvement in the real-time monitoring of plant conditions thanks to the use of PEDOT:PSS, a well-known polymer for sensor applications characterized by an ionic and electronic current. The use of the OECT in the field of monitoring on plants has produced various scientific papers concerning the monitoring of water flows [ 127 ], ionic concentrations [ 5 ] or glucose inside plants [ 128 ], and recently, EGOFETs have also been exploited for monitoring bacterial infections in plants [ 129 ]. Gentile et al in 2022 proposed an OECT integrated into the stem of a tomato plant for the real-time detection of the concentration and saturation levels of ions.…”

Materials-Functionalized Point-of-Care Testing Devices for Pathogen Detection

“…The functional materials at interfaces between POCT devices and biological samples, including inorganic nanomaterials, organic polymers, and biomaterials, are critical for improving the analytical performance of POCT devices. , The functional materials can provide higher sensitivity and specificity, streamline the sample handling, or serve as supporting substrates for POCT devices . Hence, the development of functional materials for POCT devices has real-world implications for the fast and large-scale detection of pathogens …”