Recent Progress in Gas Sensors Based on P3HT Polymer Field-Effect Transistors.

In recent decades, the rapid development of the global economy has led to a substantial increase in energy consumption, subsequently resulting in the emission of a significant quantity of toxic gases into the environment. So far, gas sensors based on polymer field-effect transistors (PFETs), a highly practical and cost-efficient strategy, have garnered considerable attention, primarily attributed to their inherent advantages of offering a plethora of material choices, robust flexibility, and cost-effectiveness. Notably, the development of functional organic semiconductors (OSCs), such as poly(3-hexylthiophene-2,5-diyl) (P3HT), has been the subject of extensive scholarly investigation in recent years due to its widespread availability and remarkable sensing characteristics. This paper provides an exhaustive overview encompassing the production, functionalization strategies, and practical applications of gas sensors incorporating P3HT as the OSC layer. The exceptional sensing attributes and wide-ranging utility of P3HT position it as a promising candidate for improving PFET-based gas sensors.

Single Molecule Level and Label-Free Determination of Multibiomarkers with an Organic Field-Effect Transistor Platform in Early Cancer Diagnosis.

The single molecule level determination with a transistor (SiMoT) platform has attracted considerable attention in the recognition of various ultralow abundance biomolecules, while complicated labeling and testing processes limit its further applications. Recently, organic field-effect transistor (OFET)-based biosensors are good candidates for constructing an advanced label-free SiMoT platform due to their facile fabrication process, rapid response time, and low sample volume with a wide range of detection. However, the sensitivity of most OFET-based biosensors is in the order of nM and pM, which cannot meet the detection requirements of ultralow abundance protein. Herein, a label-free SiMoT platform is demonstrated by integrating pillar[n]arene as a signal amplifier, and the detection limit can reach 4.75 aM. Besides, by simultaneous determination of α-fetoprotein, carcinoembryonic antigen, and prostate antigen, the proposed multiplexed OFET-based SiMoT platform provides a key step in reliable early cancer diagnosis.

Facile Functionalization Strategy for Ultrasensitive Organic Protein Biochips in Multi-Biomarker Determination.

In recent years, organic field-effect transistors (OFETs) have shown great potential for advanced protein biochips due to their inherent biocompatibility and high-throughput detectability. However, the development of OFET-based protein biochips is still at an early stage. On the one hand, single-biomarker determination is not sufficient for the diagnosis of cancer; thus, simultaneous monitoring of electrical signals toward multi-biomarkers is widely concerned and explored. On the other hand, an optimized functionalization strategy for efficient protein immobilization is another key to make OFET-based protein biochips accessible with improved detection performance. Herein, a facile functionalization strategy is developed for excellent charge-transport thin films by suppressing the gelation of diketopyrrolopyrrole (DPP)-based polymer semiconductors with the addition of the glutaraldehyde cross-linking agent. Besides, functional groups are introduced on the device surface for efficient attachment of antibodies as receptors via a condensation reaction, enabling simultaneous determination of α-fetoprotein biomarker and carcinoembryonic antigen biomarker with improved sensitivity and reliability. Therefore, the proposed high-throughput OFET-based protein biochip has the potential to be widely utilized in early liver cancer diagnosis.

Organic Field-Effect Transistor-Based Biosensors with Enhanced Sensitivity and Reliability under Illumination for Carcinoembryonic Antigen Bioassay.

Achieving biosensors of high sensitivity and reliability is extremely significant for early diagnosis and treatment of tumor diseases. Herein, a novel organic field-effect transistor (OFET)-based biosensor was developed and applied for carcinoembryonic antigen (CEA) bioassay. This OFET-based biosensor can respond sensitively to the antigen-antibody immune-recognition reaction under illumination and darkness, respectively, thereby generating electrical signal changes of source-drain current (IDS) and threshold voltage (Vth). The OFET-based biosensor exhibits detection limits for CEA detection of 0.5 and 0.2 pM, respectively, using IDS and Vth as the response signals under darkness. When a specific intensity of light is applied, light will influence the charge-carrier transport process in the conductive channel, thus causing biosignals to turn into higher electrical signal changes of photocurrent and threshold voltage under illumination. Compared with the detection results in the dark, the biosensor exhibits higher sensitivity for CEA detection under illumination with detection limits of 13.5 and 16.9 fM. Also, multisignal outputs effectively improve the reliability of the biosensor for CEA detection. Consequently, with powerful detection functions, this OFET-based biosensor is expected to become a high-performance biosensing platform for the detection of various biological substances in the future.

Ultrasensitive and Reliable Organic Field-Effect Transistor-Based Biosensors in Early Liver Cancer Diagnosis.

Organic field-effect transistors (OFETs) are considered as one of the cost-effective biosensor devices with rapid detection capabilities and multiparameter responses. However, the functionalization processes on normal organic devices might impact the device performance for its further sensitive and reliable sensing applications. Herein, we develop a novel organic material, 2,6-bis(4-formylphenyl)anthracene (BFPA) for use as the protective and functional layer of OFET-based biosensors, enabling ultrasensitive determination of alpha-fetoprotein (AFP) with femtomolar accuracy in human serum. By monitoring changes of the source-drain current (Ids) and threshold voltage (Vth) electrical signals, the device exhibits improved reliability in detecting AFP biomarkers and is able to differentiate between liver cancer patients and healthy individuals. Featuring label-free determination, shorter analysis time, and lower sample volume, this ultrasensitive and reliable OFET-based biosensor displays numerous advantages over traditional strategies such as enzyme-linked immunosorbent assay and electrochemiluminescence immunoassay, demonstrating that the proposed OFET-based biosensors have broader analytical and clinical applications for early liver cancer diagnosis.

Ternary Conductance Switching Realized by a Pillar[5]arene-Functionalized Two-Dimensional Imine Polymer Film.

Nowadays, most manufacturing memory devices are based on materials with electrical bistability (i. e., "0" and "1") in response to an applied electric field. Memory devices with multilevel states are highly desired so as to produce high-density and efficient memory devices. Herein, we report the first multichannel strategy to realize a ternary-state memristor. We make use of the intrinsic sub-nanometer channel of pillar[5]arene and nanometer channel of a two-dimensional imine polymer to construct an active layer with multilevel channels for ternary memory devices. Low threshold voltage, long retention time, clearly distinguishable resistance states, high ON/OFF ratio (OFF/ON1/ON2=1 : 10 : 103 ), and high ternary yield (75 %) were obtained. In addition, the flexible memory device based on 2DPTPAZ+TAPB can maintain its stable ternary memory performance after being bent 500 times. The device also exhibits excellent thermal stability and can tolerate a temperature as high as 300 °C. It is envisioned that the results of this work will open up possibilities for multistate, flexible resistive memories with good thermal stability and low energy consumption, and broaden the application of pillar[n]arene.

Organic thin-film transistors and related devices in life and health monitoring.

The early determination of disease-related biomarkers can significantly improve the survival rate of patients. Thus, a series of explorations for new diagnosis technologies, such as optical and electrochemical methods, have been devoted to life and health monitoring. Organic thin-film transistor (OTFT), as a state-of-the-art nano-sensing technology, has attracted significant attention from construction to application owing to the merits of being label-free, low-cost, facial, and rapid detection with multi-parameter responses. Nevertheless, interference from non-specific adsorption is inevitable in complex biological samples such as body liquid and exhaled gas, so the reliability and accuracy of the biosensor need to be further improved while ensuring sensitivity, selectivity, and stability. Herein, we overviewed the composition, mechanism, and construction strategies of OTFTs for the practical determination of disease-related biomarkers in both body fluids and exhaled gas. The results show that the realization of bio-inspired applications will come true with the rapid development of high-effective OTFTs and related devices. Electronic Supplementary Material: Supplementary material is available in the online version of this article at 10.1007/s12274-023-5606-1.

Carbon dots-functionalized extended gate organic field effect transistor-based biosensors for low abundance proteins.

Organic field effect transistors have emerged as promising platforms for biosensing applications. However, the challenge lies in optimizing functionalization strategies for the sensing interface, enabling the simultaneous detection of low abundance proteins while maintaining device performance. Here, we designed a carbon dots-functionalized extended gate organic field effect transistor. Leveraging the advantages of facile synthesis, tunable modification, small particle size, and cost-effectiveness of carbon dots, we implemented their integration onto the electrode surface. Through harnessing the covalent interactions of functional groups on the surface of carbon dots, we achieved effective immobilization of low abundance proteins without compromising device performance. Consequently, this biosensor exhibits a remarkably low limit of detection of 2.7 pg mL-1 and demonstrates high selectivity for the carcinoembryonic antigen. These findings highlight the superior capabilities of carbon dots in enhancing biosensor performance and emphasize their potential for early cancer detection.

Facile and cost-effective liver cancer diagnosis by water-gated organic field-effect transistors.

The rise of mortality rate caused by hepatocellular carcinoma accelerates requirements of biosensors for early liver cancer diagnosis and treatment to improve the clinical prognosis and prolong the survival of patients. However, how to realize label-free, low-cost, easy and fast-detection is the major challenge in the design of biosensors. Water-gated organic field-effect transistors efficiently bridge the gap between semiconductor devices and biological systems, leading to an organic device suitable for health or body signal monitoring. Herein, a kind of high-performance water-gated organic field-effect transistor is developed through the optimization process. This method provides a label-free general sensing platform for the determination of liver cancer biomarker alpha-fetoprotein in 45 minutes, much quicker than traditional methods such as the enzyme-linked immunosorbent assay for several hours. In addition, with the detection limit lower than the cut-off value as well as the ability to achieve quantitative detection, this novel water-gated organic field-effect transistor enables a much broader analysis of other biomarkers in cancer patient samples.