Ultra-sensitive protein detection with organic electrochemical transistors printed on plastic substrates

Abstract

The detection of protein biomarkers is of great importance in the early diagnosis of severe pathological states. Although in the last decade many approaches to achieve ultra-sensitive protein detection have been developed, most of them require complicated assay set-ups, hindering their adoption in point-of-care applications and on-spot diagnosis. Here we show an organic electrochemical transistor (OECT) biosensor printed on plastic substrates that can selectively detect Immunoglobulin G (IgG) with unprecedented attomolar detection limit. The OECT is used as a transducer of the biorecognition event taking place at the gate electrode. The measured concentrations are well below the detectable limits of the leading clinical diagnostic ELISA assay, and comparable to the ones gathered with the label-needing single molecule arrays (SiMoA) platform. Our work benchmarks the role of plastic OECT-based biosensors as a powerful tool in simple, low-cost, yet non-invasive, ultra-sensitive, and widely applicable immunoassay technology.

Ultimately Sensitive Organic Bioelectronic Transistor Sensors by Materials and Device Structure Design

“…In this case, no conceptual difference exists with EGOFETs, the only difference being C OSC switching from a 2D to a 3D capacitance. Indeed, PEDOT:PSS has been shown to be capable of working in an EGOFET bioelectronic sensing structure, too …”

“…The device was able to detect DNA targets at concentrations as low as 1 × 10 −9 m and its detection limit reached 10 × 10 −12 m by pulse‐enhanced hybridization of DNA . Even better performance level was achieved in the detection of immunoglobulin G (IgG) with an unprecedented attomolar detection limit . In this case, the anti‐IgG is the recognition element that is attached to the gold gate and the PEDOT:PSS is capacity coupled to the sensing gate.…”

“…In fact, for glucose a LOD of 0.1 × 10 −6 m has been reported, for gallic acid the LOD is 10.7 × 10 −9 m , for dopamine it is 0.1 × 10 −9 m , and for uric acid it is 0.12 μΜ . Moreover, an EGOFET detecting dopamine at lower concentration, than an OECT, has been reported, while a capacity‐coupled OECT has been proven to detect at the attomolar limit …”

“…However, reference electrodes have not yet been successfully integrated in an electronic circuit, and this drawback has impaired the commercialization of electrochemical‐sensor arrays. The need for such an element can be less critical in capacity‐coupling regimes as no I G flows and, indeed, EGOFETs are generally stably operated with no reference electrode . Indeed, even with an EGOFET, more stable potentials are measured with the use of a reference electrode.…”

“…Among the others, electrolyte‐gated organic field‐effect transistors (EGOFETs) have been proposed as sensors . Relevantly, EGOFET sensors have been proven to reach limit of detections (LODs) in the 10 −18 m (attomolar) range . Very recently, they have been proven capable of detecting biomarkers at the physical limit reaching LODs of 10 −21 m (zeptomolar) with a technology called “Single Molecule with a large Transistor” (SiMoT) .…”