Layered Double Hydroxide-Modified Organic Electrochemical Transistor for Glucose and Lactate Biosensing

Abstract

Biosensors based on Organic Electrochemical Transistors (OECTs) are developed for the selective detection of glucose and lactate. The transistor architecture provides signal amplification (gain) with respect to the simple amperometric response. The biosensors are based on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) channel and the gate electrode is functionalised with glucose oxidase (GOx) or lactate oxidase (LOx) enzymes, which are immobilised within a Ni/Al Layered Double Hydroxide (LDH) through a one-step electrodeposition procedure. The here-designed OECT architecture allows minimising the required amount of enzyme during electrodeposition. The output signal of the biosensor is the drain current (Id), which decreases as the analyte concentration increases. In the optimised conditions, the biosensor responds to glucose in the range of 0.1–8.0 mM with a limit of detection (LOD) of 0.02 mM. Two regimes of proportionality are observed. For concentrations lower than 1.0 mM, a linear response is obtained with a mean gain of 360, whereas for concentrations higher than 1.0 mM, Id is proportional to the logarithm of glucose concentration, with a gain of 220. For lactate detection, the biosensor response is linear in the whole concentration range (0.05–8.0 mM). A LOD of 0.04 mM is reached, with a net gain equal to 400.

Organic Electrochemical Transistors: An Emerging Technology for Biosensing

“…The most common metabolites targeted in the literature are glucose and lactate, both of which are physiologically relevant bioanalytes to indicate overall human or animal health. [ 90 ] An early example of an OECT‐based glucose sensor consisted of a PEDOT:PSS channel material, a Pt gate electrode, with glucose and glucose oxidase dissolved in the electrolyte. Oxidation of D‐glucose to D‐glucono‐1,5‐lactone was followed by reactivation (oxidation) of the enzyme by oxygen, to produce hydrogen peroxide.…”

“…LO x can be immobilized on the gate electrode by a variety of methods. [ 7,81,90,98 ] One of these methods involves utilizing a Ni/Al layered double hydroxide (LDH), the advantages of which include biocompatibility, uninhibited mobility of the analyte, high chemical and ambient stability, and a facile one‐step electrochemical deposition. [ 90 ] Whilst the use of a Ni/Al LDH has previously been demonstrated on a Pt gate electrode, [ 99,100 ] this work developed its use on Au electrodes, successfully improving sensitivity to glucose and lactate, while also demonstrating its versatility to different enzymes.…”

Textile Chemical Sensors Based on Conductive Polymers for the Analysis of Sweat

“…The gate electrode is typically functionalized with GOx or LOx to oxidize glucose or lactate, respectively [ 113 ], to generate an electrical signal following the same pathways of amperometric sensors, with the major advantage that no reference electrode is required when using a transistor configuration. The enzyme catalyzes the oxidation event that generates a change in the effective gate voltage and affects the channel current [ 114 , 115 , 116 ].…”

Highly Conductive Polymer PEDOT: PSS - Application in Biomedical and Bioelectrochemical Systems

“…The biosensor was successfully applied to detect glucose levels in saliva. In [28], a similar transistor was used to determine both glucose and lactate. For immobilization of the enzymes, a simple, fast and reproduction procedure has been performed based on one-step electrochemical co-deposition of the glucose oxidase enzyme (GOD) or lactate dehydrogenase (LDH) and the particles of Ni-Al Layered double hydroxide (Fig.…”