High-Performance Extended-Gate Field-Effect Transistor for Kinase Sensing in Aβ Accumulation of Alzheimer’s Disease

A novel Alzheimer detection rapid-testing low-cost technique by a gate engineered gate stack dual-gate FET device

This study explores a quick, low-cost method to detect Alzheimer's disease (AD) by evaluating the accomplishment of a Gate-Stack (GS) Field Effect Transistor (FET). We investigate Single-Metal (SM), Dual-Metal (DM), and Tri-Metal Double Gate (DG) configurations, where cavities have been created by etching the oxide layer underneath the gate to immobilize grey matter samples collected through Solid-phase microextraction (SPME). Healthy and AD-affected grey matter have different dielectric characteristics at high frequencies. The dielectric constant of the etched nanocavities changes when the sample, which was formerly filled with air, is immobilized in the nanocavities. The alteration in the device drain current as well as performance at 2.4 GHz has been connected to the specimen's modified dielectric constant. To distinguish between the grey matter samples from AD patients and healthy individuals, the ION/IOFF of the suggested device along with the variation in device drain current, has been utilized as the foundation for the identification. The SM configuration has been examined by varying the cavity orientation and gate oxide stacking. To monitor the functioning of the suggested devices, the gate metal of the DM and TM devices has been altered, and a comparison has been made between SM, DM, and TM structures. The other recorded work from literature has been compared with the suggested detection technique. To ascertain whether the sample is impacted by AD, the proposed method can be used as a point of care (POC) diagnosis.

Enhanced detection of Brain-Derived Neurotrophic Factor (BDNF) using a reduced graphene oxide field-effect transistor aptasensor

Neurodegenerative diseases, characterized by the progressive deterioration of neuronal function and structure, pose significant global public health and economic challenges. Brain-Derived Neurotrophic Factor (BDNF), a key regulator of neuroplasticity and neuronal survival, has emerged as a critical biomarker for various neurodegenerative and psychiatric disorders, including Alzheimer's disease. Traditional diagnostic methods, such as Enzyme-Linked Immunosorbent Assay (ELISA) and electrochemiluminescence (ECL) assays, face limitations in terms of sensitivity, stability, reproducibility, and cost-effectiveness. In this research, we developed the first electrical aptasensor for BDNF detection, constructed on a flexible polyimide (PI) membrane coated with reduced graphene oxide (r-GO) and utilized an extended-gate field-effect transistor (EGFET) as the transducer. Comprehensive characterization of the sensor, coupled with the fine-tuning of aptamer concentration and the binding time of DNA aptamers to the chemical linker, was achieved through Electrochemical Impedance Spectroscopy (EIS) to boost sensitivity. Consequently, by utilizing the unique properties of r-GO and DNA aptamers, the aptasensor exhibited exceptional detection abilities, with a detection limit as low as 0.4 nM and an extensive response range spanning from 0.025 to 1000 nM. The flexible PI-based electrode offers exceptional stability, affordability, and durability for home diagnostics, enriched by the reusability of its electronic transducer, making the device highly portable and suitable for prolonged monitoring. Our aptasensor surpasses traditional methods, showcasing superior real-time performance and reliability. The high sensitivity and specificity of our aptasensor highlight its potential to significantly improve early diagnosis and therapeutic monitoring of neurodegenerative diseases such as Alzheimer's, representing a considerable advancement in the diagnosis and management of such conditions.

Protein Detection Based on Field-Effect Transistor Biosensors for Diagnosing Diseases

Proteins have been one of the most important biomarkers for diagnosing diseases, and field-effect transistor (FET) biosensors possess high sensitivity; are label-free; and feature real-time detection, rapidity, and easy integration for protein detection. FET biosensors are mainly made up of FET parts, such as channel materials, and bio parts, such as receptors. This Tutorial provides an in-depth exploration of FET biosensors for protein detection from the composition perspective and discusses the commercialization of point-of-care diagnostics of proteins based on FET biosensors.

Active-matrix extended-gate field-effect transistor array for simultaneous detection of multiple metabolites

With the deepening understanding of diseases, increasing attention has been paid to personalized healthcare and precise diagnosis, which usually depend on the simultaneous monitoring of multiple metabolites, therefore requiring biological sensing systems to possess high sensitivity, specificity, throughput, and instant monitoring capabilities. In this work, we demonstrated the active-matrix extended-gate field-effect transistor (AMEGFET) array that can perform instant analysis of various metabolites in small amounts of body fluids collected during routine physiological activities. The extended gate electrodes of the AMEGFETs comprise ordered mesoporous carbon fibers loaded with both oxidoreductase enzymes for specific metabolites and platinum nanoparticles. By selecting customized electrode combinations, the AMEGFET array can monitor the concentrations of metabolites closely associated with chronic diseases and lifestyles, such as glucose, uric acid, cholesterol, ethanol, and lactate. The switch function of AMEGFET not only simplifies the readout circuitry for large-scale arrays but also avoids the mutual interferences among sensing units. The high flexibility and scalability make the AMEGFET array widely applicable in establishing high-throughput sensing platforms for biomarkers, providing highly efficient technical support for proactive health and intelligent healthcare.

Laser-induced multi-doped graphene extended-gate field-effect transistor sensor for enhanced detection of cystatin C

In this study, we amplified the capabilities of laser-induced graphene (LIG) by developing a multi-doped LIG extended-gated field-effect transistor (EG-FET) sensor. This sensor integrates a multi-doped LIG EG electrode array as a disposable sensing component with a standard MOSFET for reusable transduction. The multi-doped LIG was synthesized using a dual-approach: initially, by using a MnCl2-doped polyimide (MnCl2-PI) film through precursor compounding, and subsequently, by employing a CO2 laser to respectively in situ generate MnO2 nanoparticles and gold nanoparticles (Au NPs) via direct laser conversion. By incorporating the resultant multi-doped LIG (Au NPs/MnO2/LIG) as the EG electrode, we boosted its electrical efficiency and provided ideal sites for the papain immobilization. This facilitated the selective binding of protein complexes with cystatin C (Cys C), allowing for precise measurement. Notably, the sensor exhibited a robust linear correlation across a concentration range from 50 ag/μL to 0.25 ng/μL and achieved a detection limit of 50 ag/μL. These advancements not only address traditional limitations of LIG applications but also highlight the potential of LIG-based EG-FET portable devices for accurate and early screening of chronic kidney disease (CKD).

Ultrasensitive sensing urinary cystatin C via an interface-engineered graphene extended-gate field-effect transistor for non-invasive diagnosis of chronic kidney disease

Early chronic kidney disease (CKD) has strong concealment and lacks an efficient, non-invasive, and lable-free detection platform. Cystatin C (Cys C) in urine is closely related to the progress of CKD (especially at the early stage), which is an ideal endogenous marker to evaluate the impairment of renal function. Thus, the accurate detection of urinary Cys C (u-Cys C) is great significant for early prevention and treatment and delaying the course of the disease of CKD patients. Herein, we developed an extended-gate field-effect transistor (EG-FET) sensor for ultrasensitive detection of u-Cys C, which consists of a monolithic interface-engineered graphene EG electrode array and a commercially available MOSFET. Laser-induced graphene (LIG) loaded with sputtered Au NPs in the presence of adhesive Cr (Au NPs/Cr/LIG) boosts the electrical performance of the EG electrode. Meanwhile, Au NPs also serve as linkers to immobilize papain that can selectively form protein complexes with Cys C. Supported by the synergistic effect of multilevel interface-engineered graphene, our sensor exhibits a good linear correlation within the u-Cys C concentration range of 5 ag/μL to 50 ng/μL with low detection limit of 0.05 ag/μL. Our work makes accurate, specific and rapid detection of u-Cys C feasible and promising for early screening for CKD.

Interface-Engineered Field-Effect Transistor Electronic Devices for Biosensing

Promising advances in molecular medicine have promoted the urgent requirement for reliable and sensitive diagnostic tools. Electronic biosensing devices based on field-effect transistors (FETs) exhibit a wide range of benefits, including rapid and label-free detection, high sensitivity, easy operation, and capability of integration, possessing significant potential for application in disease screening and health monitoring. In this perspective, the tremendous efforts and achievements in the development of high-performance FET biosensors in the past decade are summarized, with emphasis on the interface engineering of FET-based electrical platforms for biomolecule identification. First, an overview of engineering strategies for interface modulation and recognition element design is discussed in detail. For a further step, the applications of FET-based electrical devices for in vitro detection and real-time monitoring in biological systems are comprehensively reviewed. Finally, the key opportunities and challenges of FET-based electronic devices in biosensing are discussed. It is anticipated that a comprehensive understanding of interface engineering strategies in FET biosensors will inspire additional techniques for developing highly sensitive, specific, and stable FET biosensors as well as emerging designs for next-generation biosensing electronics.

Methods gold standard in clinic millifluidics multiplexed extended gate field-effect transistor biosensor with gold nanoantennae as signal amplifiers

We present a portable multiplexed biosensor platform based on the extended gate field-effect transistor and demonstrate its amplified response thanks to gold nanoparticle-based bioconjugates introduced as a part of the immunoassay. The platform comprises a disposable chip hosting an array of 32 extended gate electrodes, a readout module based on a single transistor operating in constant charge mode, and a multiplexer to scan sensing electrodes one-by-one. Although employing only off-the-shelf electronic components, our platform achieves sensitivities comparable to fully customized nanofabricated potentiometric sensors. In particular, it reaches a detection limit of 0.2 fM for the pure molecular assay when sensing horseradish peroxidase-linked secondary antibody (∼0.4 nM reached by standard microplate methods). Furthermore, with the gold nanoparticle bioconjugation format, we demonstrate ca. 5-fold amplification of the potentiometric response compared to a pure molecular assay, at the detection limit of 13.3 fM. Finally, we elaborate on the mechanism of this amplification and propose that nanoparticle-mediated disruption of the diffusion barrier layer is the main contributor to the potentiometric signal enhancement. These results show the great potential of our portable, sensitive, and cost-efficient biosensor for multidimensional diagnostics in the clinical and laboratory settings, including e.g., serological tests or pathogen screening.

Multi-engineered Graphene Extended-Gate Field-Effect Transistor for Peroxynitrite Sensing in Alzheimer's Disease

The expression of β-amyloid peptides (Aβ), a pathological indicator of Alzheimer's disease (AD), was reported to be inapparent in the early stage of AD. While peroxynitrite (ONOO-) is produced excessively and emerges earlier than Aβ plaques in the progression of AD, it is thus significant to sensitively detect ONOO- for early diagnosis of AD and its pathological research. Herein, we unveiled an integrated sensor for monitoring ONOO-, which consisted of a commercially available field-effect transistor (FET) and a high-performance multi-engineered graphene extended-gate (EG) electrode. In the configuration of the presented EG electrode, laser-induced graphene (LIG) intercalated with MnO2 nanoparticles (MnO2/LIG) can improve the electrical properties of LIG and the sensitivity of the sensor, and graphene oxide (GO)-MnO2/Hemin nanozyme with ONOO- isomerase activity can selectively trigger the isomerization of ONOO- to NO3-. With this synergistic effect, our EG-FET sensor can respond to the ONOO- with high sensitivity and selectivity. Moreover, taking advantage of our EG-FET sensor, we modularly assembled a portable sensing platform for wireless tracking ONOO- levels in the brain tissue of AD transgenic mice at earlier stages before massive Aβ plaques appeared, and we systematically explored the complex role of ONOO- in the occurrence and development of AD.

Advanced Temporally-Spatially Precise Technologies for On-Demand Neurological Disorder Intervention

Temporal-spatial precision has attracted increasing attention for the clinical intervention of neurological disorders (NDs) to mitigate adverse effects of traditional treatments and achieve point-of-care medicine. Inspiring steps forward in this field have been witnessed in recent years, giving the credit to multi-discipline efforts from neurobiology, bioengineering, chemical materials, artificial intelligence, and so on, exhibiting valuable clinical translation potential. In this review, the latest progress in advanced temporally-spatially precise clinical intervention is highlighted, including localized parenchyma drug delivery, precise neuromodulation, as well as biological signal detection to trigger closed-loop control. Their clinical potential in both central and peripheral nervous systems is illustrated meticulously related to typical diseases. The challenges relative to biosafety and scaled production as well as their future perspectives are also discussed in detail. Notably, these intelligent temporally-spatially precision intervention systems could lead the frontier in the near future, demonstrating significant clinical value to support billions of patients plagued with NDs.

Light-Activated Interface Charge-Alternating Interaction on an Extended Gate Photoelectrode: A New Sensing Strategy for EGFET-Based Photoelectrochemical Sensors

Integration of extended gate field-effect transistors (EGFET) and photoelectrochemical (PEC) measurement to construct highly sensitive sensors is an innovative research field that was proven feasible by our previous work. However, it remains a challenge on how to adjust the interaction between the extended gate and the analyte and study its influence on EGFET-based PEC sensors. Herein, a new sensing strategy was proposed by a mutual electrostatic interaction. Three-dimensional TiO₂ and g-C₃N₄ core-shell heterojunction on flexible carbon cloth (TCN) was designed as the extended sensing gate. Tetracycline (TC) was also used as a model analyte, and it contains electron-donating groups (-NH₂ and -OH) with negative charge. The designed TCN-extended sensing gate was negatively charged in the dark by introducing carbon vacancies with oxygen doping in the g-C₃N₄ shell, while it was positively charged under illustration due to the aggregation of photogenerated holes on the surface. Therefore, a light-activated PEC sensing platform for the sensitive and selective determination of tetracycline (TC) was demonstrated. Such a PEC sensor exhibited wide linear ranges within 100 pM to 1 μM and 1-100 μM with a low detection limit of 0.42 pM. Furthermore, the sensing platform possessed excellent selectivity, good reproducibility, and stability. The proposed sensing strategy in this work can expand the paradigm for developing a light-regulated FET-based PEC sensor by mutual electrostatic interaction, and we believe that this work will offer a new perspective for the design of interface interaction in PEC devices.

Dextran-assisted ultrasonic exfoliation of two-dimensional metal-organic frameworks to evaluate acetylcholinesterase activity and inhibitor screening

Acetylcholinesterase (AChE) is regarded as a biomarker of Alzheimer's disease (AD), and its inhibitors show great potential in AD therapy as AChE can increase the neurotoxicity of the amyloid component that induces AD. Because of this, it is crucial and significant to develop a simple and highly sensitive strategy to monitor AChE levels and screen highly efficient AChE inhibitors. Herein, we synthesize an ultrathin two-dimensional (2D) metal-organic framework (MOF) based on copper-catecholate (Cu-CAT) via dextran assisted ultrasound exfoliation, followed by construction of a sensitive sensor for the monitoring AChE and screening of its inhibitors. By adding AChE, the acetylthiocholine (ATCh) substrate is hydrolyzed to be thiocholine (TCh), which decreases the peroxidase-like activity of Cu-CAT nanosheets (Cu-CAT NSs), impairing the signal reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized-TMB (ox-TMB). In the presence of an AChE inhibitor, the signal can be gradually restored. The newly developed sensor shows high sensitivity and selectivity for AChE and huperzine A (HA, an effective drug for AD, an acetylcholine receptor antagonist), as well as for AD drug discovery from traditional Chinese herbs. The limit of detection of the sensor for AChE is 0.01 mU mL^-1 and the average IC₅₀ value of HA is 30.81 nM under the optimal of catalysis conditions. Compared with the 3D bulk Cu-CAT, the current 2D Cu-CAT NSs exhibit higher peroxidase activity due to more catalytic active site exposure. This study provides a strategy to prepare an ultrathin 2D MOF with high catalytic activity and new insights for the construction of a biosensor to monitor AChE and new AD drugs.

FDA-Approved Kinase Inhibitors in Preclinical and Clinical Trials for Neurological Disorders

Cancers and neurological disorders are two major types of diseases. We previously developed a new concept termed "Aberrant Cell Cycle Diseases" (ACCD), revealing that these two diseases share a common mechanism of aberrant cell cycle re-entry. The aberrant cell cycle re-entry is manifested as kinase/oncogene activation and tumor suppressor inactivation, which are hallmarks of both tumor growth in cancers and neuronal death in neurological disorders. Therefore, some cancer therapies (e.g., kinase inhibition, tumor suppressor elevation) can be leveraged for neurological treatments. The United States Food and Drug Administration (US FDA) has so far approved 74 kinase inhibitors, with numerous other kinase inhibitors in clinical trials, mostly for the treatment of cancers. In contrast, there are dire unmet needs of FDA-approved drugs for neurological treatments, such as Alzheimer's disease (AD), intracerebral hemorrhage (ICH), ischemic stroke (IS), traumatic brain injury (TBI), and others. In this review, we list these 74 FDA-approved kinase-targeted drugs and identify those that have been reported in preclinical and/or clinical trials for neurological disorders, with a purpose of discussing the feasibility and applicability of leveraging these cancer drugs (FDA-approved kinase inhibitors) for neurological treatments.

Aptamer-engineered extended-gate field-effect transistor device for point-of-care therapeutic drug monitoring

A portable point-of-care testing (POCT) device based on an aptamer-engineered extended-gate field-effect transistor (EG-FET) was unveiled for therapeutic monitoring of the drug methotrexate.