Organic electrochemical transistor for sensing of sialic acid in serum samples

Extended Review Concerning the Integration of Electrochemical Biosensors into Modern IoT and Wearable Devices

Electrochemical biosensors include a recognition component and an electronic transducer, which detect the body fluids with a high degree of accuracy. More importantly, they generate timely readings of the related physiological parameters, and they are suitable for integration into portable, wearable and implantable devices that are significant relative to point-of-care diagnostics scenarios. As an example, the personal glucose meter fundamentally improves the management of diabetes in the comfort of the patients' homes. This review paper analyzes the principles of electrochemical biosensing and the structural features of electrochemical biosensors relative to the implementation of health monitoring and disease diagnostics strategies. The analysis particularly considers the integration of the biosensors into wearable, portable, and implantable systems. The fundamental aim of this paper is to present and critically evaluate the identified significant developments in the scope of electrochemical biosensing for preventive and customized point-of-care diagnostic devices. The paper also approaches the most important engineering challenges that should be addressed in order to improve the sensing accuracy, and enable multiplexing and one-step processes, which mediate the integration of electrochemical biosensing devices into digital healthcare scenarios.

Additive Blending Effects on PEDOT:PSS Composite Films for Wearable Organic Electrochemical Transistors

Organic electrochemical transistors (OECTs) employing conductive polymers (CPs) have gained remarkable prominence and have undergone extensive advancements in wearable and implantable bioelectronic applications in recent years. Among the diverse arrays of CPs, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a common choice for the active-layer channel in p-type OECTs, showing a remarkably high transconductance for the high amplification of signals in biosensing applications. This investigation focuses on the novel engineering of PEDOT:PSS composite materials by seamlessly integrating several additives, namely, dimethyl sulfoxide (DMSO), (3-glycidyloxypropyl)trimethoxysilane (GOPS), and a nonionic fluorosurfactant (NIFS), to fine-tune their electrical conductivity, self-healing capability, and stretchability. To elucidate the intricate influences of the DMSO, GOPS, and NIFS additives on the formation of PEDOT:PSS composite films, theoretical calculations were performed, encompassing the solubility parameters and surface energies of the constituent components of the NIFS, PEDOT, PSS, and PSS-GOPS polymers. Furthermore, we conducted a comprehensive array of material analyses, which reveal the intricacies of the phase separation phenomenon and its interaction with the materials' characteristics. Our research identified the optimal composition for the PEDOT:PSS composite films, characterized by outstanding self-healing and stretchable capabilities. This composition has proven to be highly effective for constructing an active-layer channel in the form of OECT-based biosensors fabricated onto polydimethylsiloxane substrates for detecting dopamine. Overall, these findings represent significant progress in the application of PEDOT:PSS composite films in wearable bioelectronics and pave the way for the development of state-of-the-art biosensing technologies.

Healthcare Monitoring Sensors Based on Organic Transistors: Surface/Interface Strategy and Performance

Organic transistors possess inherent advantages such as flexibility, biocompatibility, customizable chemical structures, solution-processability, and amplifying capabilities, making them highly promising for portable healthcare sensor applications. Through convenient and diverse modifications at the material and device surfaces or interfaces, organic transistors allow for a wide range of sensor applications spanning from chemical and biological to physical sensing. In this comprehensive review, the surface and interface engineering aspect associated with four types of typical healthcare sensors is focused. The device operation principles and sensing mechanisms are systematically analyzed and highlighted, and particularly surface/interface functionalization strategies that contribute to the enhancement of sensing performance are focused. An outlook and perspective on the critical issues and challenges in the field of healthcare sensing using organic transistors are provided as well.

Organic Electrochemical Transistors for Biomarker Detections

The improvement of living standards and the advancement of medical technology have led to an increased focus on health among individuals. Detections of biomarkers are feasible approaches to obtaining information about health status, disease progression, and response to treatment of an individual. In recent years, organic electrochemical transistors (OECTs) have demonstrated high electrical performances and effectiveness in detecting various types of biomarkers. This review provides an overview of the working principles of OECTs and their performance in detecting multiple types of biomarkers, with a focus on the recent advances and representative applications of OECTs in wearable and implantable biomarker detections, and provides a perspective for the future development of OECT-based biomarker sensors.

Device integration of electrochemical biosensors

Electrochemical biosensors incorporate a recognition element and an electronic transducer for the highly sensitive detection of analytes in body fluids. Importantly, they can provide rapid readouts and they can be integrated into portable, wearable and implantable devices for point-of-care diagnostics; for example, the personal glucose meter enables at-home assessment of blood glucose levels, greatly improving the management of diabetes. In this Review, we discuss the principles of electrochemical biosensing and the design of electrochemical biosensor devices for health monitoring and disease diagnostics, with a particular focus on device integration into wearable, portable and implantable systems. Finally, we outline the key engineering challenges that need to be addressed to improve sensing accuracy, enable multiplexing and one-step processes, and integrate electrochemical biosensing devices in digital health-care pathways.

Two Co-Based Metal-Organic Framework Isomers with Similar Metal-Carboxylate Sheets: Turn-On Ratiometric Luminescence Sensing Activities toward Biomarker N-Acetylneuraminic Acid and Discrimination of Ga3+ and In3

Two supramolecular Co-MOF isomers, namely, {[Co(L)_0.5(m-bimb)]·3H₂O}_n (LCU-115) and {[Co(L)_0.5(p-bimb)]·3H₂O}_n (LCU-116), were synthesized from an amide-containing carboxylic acid N,N″-(3,5-dicarboxylphenyl)benzene-1,4-dicarboxamide (H₄L) and two flexible positional isostructural N-containing ligands m-bimb and p-bimb (m-bimb = 1,3-bis((1H-imidazol-1-yl)methyl)benzene; p-bimb = 1,4-bis((1H-imidazol-1-yl)methyl)benzene). The carboxylate ligands connect Co(II) centers to form 2D metal-carboxylate sheets, which are extended further by m-bimb and p-bimb to form a 2D bilayer with parallel stacking (LCU-115) and a 3D framework (LCU-116), respectively. Luminescence measurements indicated that these two complexes exhibited interesting multiresponsive sensing activities toward pH, biomarker N-acetylneuraminic acid, and trivalent cations Ga³⁺/In³⁺. They show highly sensitive turn-on fluorescence responses in the acidic range and can also be regarded as on-off-on vapoluminescent sensors to typical acidic and basic gases HCl and Et₃N. It is worth noting that these complexes have excellent turn-on ratiometric fluorescence sensing ability for N-acetylneuraminic acid (NANA) with detection limits as low as 7.39 and 8.06 μM, respectively. Furthermore, they were successfully applied for the detection of NANA in simulated urine and serum samples with satisfactory results. For ion detection, LCU-116 could detect both Ga³⁺ and In³⁺, while LCU-115 could distinguish Ga³⁺ from In³⁺ with the latter showing luminescence quenching. The sensing mechanism was investigated in detail by XRD, UV-vis, EDS, XPS, SEM, and TEM. The results of interday and intraday precision studies gave low RSD values in the range of 1.19-3.53%, ascertaining the reproducibility of these sensors. The recoveries for the sensing analytes in simulated urine/serum or real water are satisfactory from 96.7 to 103.3% (toward NANA) and 96.6 to 115.0% (toward Ga³⁺ and In³⁺), indicating that these two complexes also possess acceptable reliability for monitoring in real samples. The results indicated that the supramolecular isomers LCU-115 and LCU-116 are promising material candidates for application in biological and environmental monitoring.

Electrochemical Biosensors Based on Carbon Nanomaterials for Diagnosis of Human Respiratory Diseases

In recent years, respiratory diseases have increasingly become a global concern, largely due to the outbreak of Coronavirus Disease 2019 (COVID-19). This inevitably causes great attention to be given to the development of highly efficient and minimal or non-invasive methods for the diagnosis of respiratory diseases. And electrochemical biosensors based on carbon nanomaterials show great potential in fulfilling the requirement, not only because of the superior performance of electrochemical analysis, but also given the excellent properties of the carbon nanomaterials. In this paper, we review the most recent advances in research, development and applications of electrochemical biosensors based on the use of carbon nanomaterials for diagnosis of human respiratory diseases in the last 10 years. We first briefly introduce the characteristics of several common human respiratory diseases, including influenza, COVID-19, pulmonary fibrosis, tuberculosis and lung cancer. Then, we describe the working principles and fabrication of various electrochemical biosensors based on carbon nanomaterials used for diagnosis of these respiratory diseases. Finally, we summarize the advantages, challenges, and future perspectives for the currently available electrochemical biosensors based on carbon nanomaterials for detecting human respiratory diseases.

Lanthanide Complexes for Tumor Diagnosis and Therapy by Targeting Sialic Acid

Sialic acid (SA) is overexpressed on cell membranes of tumor cells, and increased serum SA concentration has been observed in tumor-bearing patients. Herein, a series of lanthanide-containing bimetallic complexes (TDA-M-Lns) for targeting SA were prepared via coordination among luminescent lanthanide ions (Ln³⁺ = Tb³⁺, Eu³⁺, Dy³⁺, or Sm³⁺), metal ion quenchers (M²⁺ = Cu²⁺ or Co²⁺), and the organic ligand 2,2'-thiodiacetic acid (TDA). SA can competitively coordinate with Ln³⁺, resulting in the "signal-on" of the Ln³⁺. Therefore, the TDA-M-Lns can be simply used for cost-saving detection of SA in the blood samples. Among the TDA-M-Lns, TDA-Co-Eu showed the highest sensitivity to detect SA in the blood of tumor-bearing mice. Furthermore, the TDA-Co-Eu was successfully used to target SA and deposit Eu³⁺ on the surfaces of tumor cells for the inhibition of tumor cell growth and migration. The therapeutic effect of TDA-Co-Eu on a Balb/c mouse liver tumor model was evaluated. It was proved that TDA-Co-Eu can be applied for SA detection as well as for inhibiting tumor growth.

Organic Bioelectronics for In Vitro Systems

Bioelectronics have made strides in improving clinical diagnostics and precision medicine. The potential of bioelectronics for bidirectional interfacing with biology through continuous, label-free monitoring on one side and precise control of biological activity on the other has extended their application scope to in vitro systems. The advent of microfluidics and the considerable advances in reliability and complexity of in vitro models promise to eventually significantly reduce or replace animal studies, currently the gold standard in drug discovery and toxicology testing. Bioelectronics are anticipated to play a major role in this transition offering a much needed technology to push forward the drug discovery paradigm. Organic electronic materials, notably conjugated polymers, having demonstrated technological maturity in fields such as solar cells and light emitting diodes given their outstanding characteristics and versatility in processing, are the obvious route forward for bioelectronics due to their biomimetic nature, among other merits. This review highlights the advances in conjugated polymers for interfacing with biological tissue in vitro, aiming ultimately to develop next generation in vitro systems. We showcase in vitro interfacing across multiple length scales, involving biological models of varying complexity, from cell components to complex 3D cell cultures. The state of the art, the possibilities, and the challenges of conjugated polymers toward clinical translation of in vitro systems are also discussed throughout.

Transistor-Based Biomolecule Sensors: Recent Technological Advancements and Future Prospects

Transistor-based sensors have been widely recognized to be highly sensitive and reliable for point-of-care/bed-side diagnosis. In this line, a range of cutting-edge technologies has been generated to elevate the role of transistors for biomolecule detection. Detection of a wide range of clinical biomarkers has been reported using various configurations of transistors. The inordinate sensitivity of transistors to the field-effect imparts high sensitivity toward wide range of biomolecules. This overview has gleaned the present achievements with the technological advancements using high performance transistor-based sensors. This review encloses transistors incorporated with a variety of functional nanomaterials and organic elements for their excellence in selectivity and sensitivity. In addition, the technological advancements in fabrication of these microdevices or nanodevices and functionalization of the sensing elements have also been discussed. The technological gap in the realization of sensors in transistor platforms and the resulted scope for research has been discussed. Finally, foreseen technological advancements and future research perspectives are described.

Construction of a pH/TGase "Dual Key"-Responsive Gold Nano-radiosensitizer with Liver Tumor-Targeting Ability

The method of tumor microenvironment (TME)-responsive aggregation has become a promising approach to enhance treatment effect by improving the accumulation of nanoparticles in tumors. The enzymatic cross-linking strategy has widely attracted attention owing to its good aggregation stability and biocompatibility. However, the enzymes in nontumor tissue can also catalyze the cross-linking reaction and reduce accumulation of nanoparticles in tumor. In this work, a "dual key"-responsive strategy is utilized to construct a transglutaminase (TGase)/pH-responsive radiosensitizer (Au@TAcoGal) with specific aggregation behavior in hepatic tumor cells. Au@TAcoGal can retain its stability in blood circulation (pH 7.4) even in the presence of TGase in plasma. On reaching tumor sites, it can be endocytosed by hepatoma cells by the active targeting of phenylboronic acid (PBA) and aggregated under acidity and overexpression of TGase in cells. Due to its specific accumulation in hepatoma cells, radiotherapy can be operated under a lower dose of X-ray. The results show that the cellular accumulation of Au@TAcoGal increases by 30-70%, and the cell survival rate is less than 25% under X-ray irradiation. The antineoplastic results show that Au@TAcoGal exhibits a higher therapeutic effect, and the tumor inhibition rate can reach 84.21%.

A facile strategy for quantitative sensing of glycans on cell surface using organic electrochemical transistors

This work designed a facile sensing strategy for quantitation of glycans on cell surface using organic electrochemical transistors (OECTs). The sensing strategy was performed by covalently binding target cells on mercaptopropionic acid modified gate electrode for the recognition of horseradish peroxidase (HRP) labeled lectins to specific glycans on cell surface, which led to sensitive channel current signal responding to the captured HRP and thus the expression of cell surface glycans. The quantitation of glycans on cell surface was achieved by using glycan modified microspheres to simulate the cells, on which the amounts of glycans were detected with enzyme linked immunosorbent assay. The proposed sensing strategy had been used for the detection of mannose and galactose on HeLa cells with Concanavalin A and peanut agglutinin as the specific lectins, which showed 1.37 × 10⁸ mannose and 1.13 × 10⁸ galactose on each cell, respectively. By treating HeLa cells with exoglycosidases, the mannose and galactose expression levels showed the same changes as those detected with flow cytometric analysis, indicating the practical application of the OECT-based biosensor in cell surface glycan expression analysis.