Electrolyte-gated organic transistors (EGOTs) are emerging as promising devices for biosensing applications due to their high transconductance, ability to operate in liquid environments at low voltages and label-free detection capabilities. In this study, we investigate the performance of EGOTs based on the donor-acceptor polymer DPP-DTT, a material known for its high charge mobility and aqueous stability. The device was tested as a biosensor for the detection of mitochondrial DNA (mtDNA), a biomarker associated with multiple sclerosis, as a model analyte. The gate electrode was functionalized with a complementary DNA probe via surface chemistry, with functionalization efficiency validated by surface plasmon resonance and plasmon-enhanced fluorescence spectroscopy. The resulting DPP-DTT-based EGOT sensor exhibited specific detection of mtDNA in solution, with a detection range from 70 pM to 5 nM. These results highlight the potential of DPP-DTT based EGOTs as stable, sensitive platforms for biosensing applications.

Dementia is a syndrome that affects millions of people in the world, and Alzheimer's disease (AD) is the most common cause. The diagnosis of AD begins with cognitive symptoms such as mild cognitive impairment (MCI) but requires the demonstration and quantification of the underlying neuropathological processes through the measurement of specific biomarkers. Among these, the phosphorylated tau protein at threonine 181 (p-tau 181) is considered specific for AD diagnosis in people with MCI. In this work, we report the detection of p-tau 181 spanning from physiological to pathological concentrations in cerebrospinal fluids from patients with MCI. The proposed sensor is based on an electrolyte-gated organic transistor functionalized with specific anti-p-tau 181 antibodies. We analyzed the multiparametric sensor response using a Langmuir model to extract the thermodynamic affinity constant, resulting in values between 1012 and 1013. The sensor response is then correlated with the gray matter volume of the same patients from Magnetic Resonance Imaging: the resulting maps show areas in the brain where the gray matter density decreases with increasing levels of p-tau in CSF.

Electrolyte-gated organic transistors (EGOTs) exponentially amplify minute polarization changes at the gate electrode into the channel current. Antibodies grafted on the EGOT gate electrode enable specific recognition of target species, yet this strategy may not be sufficient per se to resolve the target from its antagonists. Here, a label-free EGOT immunosensor is functionalized with the antibody anti-L-enantiomer of Tryptophan (Trp), exhibiting sensitivity to Trp chirality. Nevertheless, the relative current change in transfer curves does not unambiguously differentiate L from D enantiomers in the concentration range 1 fm to 10 nm. To overcome this limitation, a multivariate principal component analysis (PCA) is applied on the set of renormalized parameters, extracted from the whole transfer curves according to our recent EGOT model: both L and D enantiomers are neatly separated by the sign of their principal components. Enantiomeric discrimination onset is 1 and 10 pm at 90% level of confidence and prediction, respectively, at least one order of magnitude lower than the enantiodiscrimination levels previously reported with EGOT biosensor. The same analysis performed on the best fit dose curves allows to discriminate L and D enantiomers down to the unprecedented level of detection of 100 fm.

The recent discovery of the PETase enzyme family offers a sustainable solution for depolymerizing poly-(ethylene terephthalate) (PET), one of the most widespread plastic compounds, under mild conditions. This enables the environmentally beneficial conversion of plastic waste into value-added products. Among this enzyme family, PETase from Ideonella sakaiensis has been the most extensively studied. Although other similar enzymes have been discovered, our knowledge about the catalytic and structural properties of this class remains limited. In this study, a PETase-like enzyme (PETase SM14) from Streptomyces sp. SM14 was heterologously produced in Escherichia coli, and its activity was tested on post-consumer plastic substrates using high-performance liquid chromatography for product quantification as well as scanning electron microscopy and atomic force microscopy for substrate surface imaging evaluation. PETase SM14 exhibited high salt tolerance (1.5 M), good heat resistance (Tm 56.26 °C), and optimal activity at pH 9.0, highlighting its potential for PET waste bioremediation. Furthermore, its X-ray crystal structure was solved at 1.43 Å resolution, revealing conserved features of the PETase family with potential relevance for future engineering applications.

PerFluoroAlkyl Substances (PFAS) are responsible of major environmental pollution worldwide, as they are both persistent and mobile. Environmental agencies impose strict regulations about PFAS in drinking water, hence, there is an urgent need for on‐field deployable, rapid, reproducible, and distributed monitoring of PFAS. This work demonstrates an ultra‐sensitive sensor for perfluoroalkyl acids based on an organic transistor whose gate is functionalized with a binary self‐assembled monolayer containing a perfluorinated molecule. The device exploits the fluorophobic effect for selectively recognizing different PFAS based on the different number of fluorous interactions, viz . fluorine‐fluorine (F···F) contacts, that can be formed. Remarkably, the organic transistor senses differences in the binding energy to linear PFAS surfactants in water of 4 ± 1 kJ mol −1 , which corresponds to one ─CF 2 ‐ unit. This device allows to quantify PFAS in water down to ppt level of detection.

Correction for ‘Investigation of transcription factor–DNA binding with electrolyte-gated organic transistors’ by Matteo Sensi et al. , J. Mater. Chem. C , 2024, 12 , 7596–7604, https://doi.org/10.1039/D4TC00260A.

Affinity-based biosensors employing surface-bound biomolecules for analyte detection are important tools in clinical diagnostics and drug development. In this context, electrolyte-gated organic transistors (EGOTs) are emerging as ultrasensitive label-free biosensors. In this study, we present an EGOT sensor integrated within a microfluidic system. The sensor utilizes the cytomegalovirus (CMV) phosphoprotein 65 as a biorecognition element to detect the pathological biomarker human anti-cytomegalovirus antibody in solution. The biorecognition element is grafted onto the gate electrode by exploiting the polyhistidine-tag technology. Real-time monitoring of the EGOT response, coupled with a two-compartment kinetic model analysis, enables the determination of analyte concentration, binding kinetics, and thermodynamics of the interaction. The analysis of the relevant kinetic parameters of the binding process yields a reliable value for the thermodynamic equilibrium constant and suggests that the measured deviations from the Langmuir binding model arise from the co-existence of binding sites with different affinities toward the antibodies.

Nuclear transcription factor Y (NF-Y) is a CCAAT-binding trimeric protein. The overexpression of the DNA-binding subunit A (NF-YA) results in deregulation of many CCAAT-dependent pro-growth genes in multiple tumor types. Exon 3 alternative splicing of NF-YA results in two different isoforms, NF-YAs (short) and NF-YAl (long), which can promote tumor proliferation or metastasis, respectively. In this work, we developed an electrolyte-gated organic transistor (EGOT) biosensor to study the binding of a NF-YAl-composed NF-Y complex to its consensus sequence. We show that by using the target DNA sequence as a probe, the device detects NF-Y in the range of 1 pM to 10 nM. Control experiments performed with oligonucleotide probes mutated in the consensus sequence exhibit weaker, though not fully hindered, binding to NF-Y compared to the response to unmutated DNA. This behavior confirms that the base pairs near the CCAAT-box also have a role in the transcription factor recognition. Furthermore, we contributed to the advancement of the present state of the art by demonstrating the ability of the EGOT biosensor to detect NF-Y in cell lysate, a fundamental step towards the development of point-of-care (POC) devices for the analysis of biopsies. The first electrolyte-gated organic transistor biosensor for the detection of a transcription factor (NF-Y) in buffer and cell lysate.

A framework for electrolyte-gated organic transistors (EGOTs) that unifies the view of interfacial capacitive coupling of electrolyte-gated organic field-effect transistors (EGOFETs) with the volumetric capacitive coupling in organic electrochemical transistors (OECTs) is proposed. The EGOT effective capacitance arises from in-series capacitances of the electrolyte/gate electrode and electrolyte/channel interfaces, and the chemical capacitance of the organic semiconductor channel whose weight with respect to the interfacial capacitance is modulated by the charge carrier density, hence by the gate voltage. The expression for chemical capacitance is derived from the DOS of the organic semiconductor, which it is assumed to exhibit exponential energy disorder in the HOMO-LUMO gap. The analytical expression of the EGOT current is assessed on experimental data and shown to accurately predict the shape of the whole transfer curve of an EGOT thus allowing to extract accurate values for the switch-on voltage and the interfacial transconductance, without assumptions on specific response regime and, in OECT, without invoking the volumetric capacitance. Interestingly, the EGOT model recovers EGOFET and OECT as limit cases and, in the latter case, explicitly represents the volumetric capacitance in terms of the energy disorder and the bandgap of the organic semiconductor.

Ambipolar electrolyte-gated transistors (EGTs) based on reduced graphene oxide (rGO) have been demonstrated as ultra-sensitive and highly specific immunosensors. However, the physics and chemistry ruling the device operation are still not fully unraveled. In this work, the aim is to elucidate the nature of the observed sensitivity of the device. Toward this aim, a physical-chemical model that, coupled with the experimental characterization of the rGO-EGT, allows one to quantitatively correlate the biorecognition events at the gate electrode and the electronic properties of rGO-EGT is proposed. The equilibrium of biorecognition occurring at the gate electrode is shown to determine the apparent charge neutrality point (CNP) of the rGO channel. The multiparametric analysis of the experimental transfer characteristics of rGO-EGT reveals that the recognition events modulate the CNP voltage, the excess carrier density Delta n, and the quantum capacitance of rGO. This analysis also explains why hole and electron carrier mobilities, interfacial capacitance, the curvature of the transfer curve, and the transconductances are insensitive to the target concentration. The understanding of the mechanisms underlying the transistor transduction of the biorecognition events is key for the interpretation of the response of the rGO-EGT immunosensors and to guide the design of novel and more sensitive devices. Ambipolar electrolyte-gated transistors based on reduced graphene oxide (rGO-EGTs) are ultra-sensitive and highly specific immunosensors. The physics and chemistry ruling the device operation are still not fully unraveled. This work aims to elucidate the nature of the observed sensitivity, by proposing a physical-chemical model that quantitatively correlates the biorecognition events at the gate electrode and the electronic properties of rGO-EGTs. image

Semiconducting single walled carbon nanotubes (SWCNTs) are promising materials for biosensing applications with electrolyte-gated transistors (EGT). However, to be employed in EGT devices, SWCNTs often require lengthy solution-processing fabrication techniques. Here, we introduce a simple solution-based method that allows fabricating EGT devices from stable dispersions of SWCNTs/bovine serum albumin (BSA) hybrids in water. The dispersion is then deposited on a substrate allowing the formation of a SWCNTs random network as the semiconducting channel. We demonstrate that this methodology allows the fabrication of EGT devices with electric performances that allow their use in biosensing applications. We demonstrate their application for the detection of cortisol in solution, upon gate electrode functionalization with anti-cortisol antibodies. This is a robust and cost-effective methodology that sets the ground for a SWCNT/BSA-based biosensing platform that allows overcoming many limitations of standard SWCNTs biosensor fabrications.

The advent of immunotherapies with biological drugs has revolutionized the treatment of cancers and auto‐immune diseases. However, in some patients, the production of anti‐drug antibodies (ADAs) hampers the drug efficacy. The concentration of ADAs is typically in the range of 1–10 pm; hence their immunodetection is challenging. ADAs toward Infliximab (IFX), a drug used to treat rheumatoid arthritis and other auto‐immune diseases, are focussed. An ambipolar electrolyte‐gated transistor (EGT) immunosensor is reported based on a reduced graphene oxide (rGO) channel and IFX bound to the gate electrode as the specific probe. The rGO‐EGTs are easy to fabricate and exhibit low voltage operations (≤ 0.3 V), a robust response within 15 min, and ultra‐high sensitivity (10 am limit of detection). A multiparametric analysis of the whole rGO‐EGT transfer curves based on the type‐I generalized extreme value distribution is proposed. It is demonstrated that it allows to selectively quantify ADAs also in the co‐presence of its antagonist tumor necrosis factor alpha (TNF‐α), the natural circulating target of IFX.

Polyethylene terephthalate hydrolases (PETases) are a newly discovered and industrially important class of enzymes that catalyze the enzymatic degradation of polyethylene terephatalate (PET), one of the most abundant plastics in the world. The greater enzymatic efficiencies of PETases compared to close relatives from the cutinase and lipase families have resulted in increasing research interest. Despite this, further characterization of PETases is essential, particularly regarding their possible activity against other kinds of plastic. In this study, we exploited for the first time the use of the microalgal chloroplast for more sustainable synthesis of a PETase enzyme. A photosynthetic-restoration strategy was used to generate a marker-free transformant line of the green microalga Chlamydomonas reinhardtii in which the PETase from Ideonella sakaiensis was constitutively expressed in the chloroplast. Subsequently, the activity of the PETase against both PET and post-consumer plastics was investigated via atomic force microscopy, revealing evidence of degradation of the plastics.

We demonstrate an organic electrochemical transistor (OECT) biosensor for the detection of interleukin 6 (IL6), an important biomarker associated with various pathological processes, including chronic inflammation, inflammaging, cancer, and severe COVID-19 infection. The biosensor is functionalized with oligonucleotide aptamers engineered to bind specifically IL6. We developed an easy functionalization strategy based on gold nanoparticles deposited onto a poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate (PEDOT:PSS) gate electrode for the subsequent electrodeposition of thiolated aptamers. During this functionalization step, the reduction of sulfide bonds allows for simultaneous deposition of a blocking agent. A detection range from picomolar to nanomolar concentrations for IL6 was achieved, and the selectivity of the device was assessed against Tumor Necrosis Factor (TNF), another cytokine involved in the inflammatory processes.

Neurofilaments are structural scaffolding proteins of the neuronal cytoskeleton. Upon axonal injury, the neurofilament light chain (NF‐L) is released into the interstitial fluid and eventually reaches the cerebrospinal fluid and blood. Therefore, NF‐L is emerging as a biomarker of neurological disorders, including neurodegenerative dementia, Parkinson's disease, and multiple sclerosis. It is challenging to quantify NF‐L in bodily fluids due to its low levels. This work reports the detection of NF‐L in aqueous solutions with an organic electronic device. The biosensor is based on the electrolyte‐gated organic field‐effect transistor (EGOFET) architecture and can quantify NF‐L down to sub‐pM levels; thanks to modification of the device gate with anti‐NF‐L antibodies imparted with potentially controlled orientation. The response is fitted to the Guggenheim–Anderson–De Boer adsorption model to describe NF‐L adsorption at the gate/electrolyte interface, to consider the formation of a strongly adsorbed protein layer bound to the antibody and the formation of weakly bound NF‐L multilayers, an interpretation which is also backed up by morphological characterization via atomic force microscopy. The label‐free, selective, and rapid response makes this EGOFET biosensor a promising tool for the diagnosis and monitoring of neuronal damages through the detection of NF‐L in physio‐pathological ranges.

Dataset of the paper "Monitoring DNA hybridization with Organic Electrochemical Transistors functionalized with Polydopamine" published in Macromolecular Materials and Engineering, DOI:10.1002/mame.202100880 The data in the excel file are organized as follows: In Transfer_fc-target tab is reported the mean of the IDS vs VGS curves for each of the datasets, for every concentration of fc-target. In Transfer_pc-target tab is reported the mean of IDS vs VGS curves for each of the datasets, for every concentration of pc-target. In Transfer_nc-target tab is reported the mean of the IDS vs VGS curves for 0 and 100 nM nc-target. In the CV tab, we show the potential vs Ag/AgCl and the current of the Cyclic Voltammetry of every gate functionalization step, shown in figure 1c of the manuscript.

The first label-free EGOFET immunosensor able to quantitatively detect anti-drug antibodies against Nivolumab, with a LOD of 100 fM.

A general single-step approach is introduced for the green fabrication of hybrid biosensors from water dispersion. The resulting device integrates the semiconducting properties of a carbon nanotube (CNT) and the functionality of a protein. In the initial aqueous phase, the protein (viz., lysozyme [LZ]) disperses the (6,5)CNT. Drop-casting of the dispersion on a test pattern (a silicon wafer with interdigitated Au source and drain electrodes) yields a fully operating, robust, electrolyte-gated transistor (EGT) in one step. The EGT response to biorecognition is then assessed using the LZ inhibitor N-acetyl glucosamine trisaccharide. Analysis of the output signal allows one to extract a protein-substrate binding constant in line with values reported for the free (without CNT) system. The methodology is robust, easy to optimize, redirectable toward different targets and sets the grounds for a new class of CNT-protein biosensors that overcome many limitations of the technology of fabrication of CNT biosensors.

Frumkin isotherm is used to fit data obtained from OECT- and EGOFET-based Intrelukin-6 biosensors and compared to the Langmuir and Hill ones. The model allows extraction of the equilibrium constantKa and the Frumkin interaction parameterg′.

The uploaded data include the transfer curves at every IL-6 concentration and for control experiments (TNFalpha and IL-1beta). Electrical measurements were acquired in 50 mM PBS, pH 7.4, containing a constant concentration of 0.1 mg/mL BSA and 0.05% Tween 20 under static conditions. Anti-IL-6 antibodies were immobilized on the gate electrode through EDC/NHS coupling onto mixed mercaptoundecanoic acid:6-mercaptohexanol (1:3) SAM.