Glucose modified carbon paste sensor in the presence of cationic surfactant for mefenamic acid detection in urine and pharmaceutical samples

Balancing performance and stability characteristics in organic electrochemical transistor

Nowadays organic electrochemical transistors (OECTs) are becoming a promising platform for bioelectronics and biosensing due to its biocompatibility, high sensitivity and selectivity, low driving voltages, high transconductance and flexibility. However, the existing problems associated with degradation processes within the OECT during long-term operation hinder their widespread implementation. Moreover, trade-offs often arise between OECT transconductance and speed, fast ion transport and electron mobility, electrochemical stability and sensitivity, cycling stability and signal amplification, and other metrics. Ensuring high performance characteristics and achieving enhanced stability in OECTs are distinct strategies that do not always align, as progress in one aspect often necessitates a trade-off with the other. This dynamic arises from the need to find a balance between reversible and irreversible processes in the behavior of OECT active layers, and providing simultaneously favorable conditions for ion and electron transport and their efficient charge coupling. This review article systematically summarizes the phenomenological and physical-chemical aspects associated with factors and mechanisms that determine both performance and long-term stability of OECT, paying special attention to the consideration of existing and promising approaches to extend the OECT lifespan, while maintaining (or even increasing) high effectiveness of its operation.

A functionalized microwave biosensor for rapid, reagent-free detection of E. coli in water samples

Escherichia coli (E. coli) O157:H7 (O157), one of the most common Shiga toxin-producing E. coli, can contaminate water systems causing severe illnesses often accompanied with diarrhea and sometimes life threatening. Frequent monitoring of E. coli in water systems is critical to protect public health. Most traditional methods for E. coli detection are slow in responding to E. coli outbreaks due to the need for sample transportation from the site to the lab, expensive equipment, and highly trained personnel for the detection. This work presents a novel reagent-free detection method that employs a microwave biosensor functionalized with an antibody specific to E. coli to offer rapid and sensitive E. coli detection. By monitoring the resonance frequency shift caused by the binding between the E. coli in the water sample and the antibody coated on the sensor using a vector network analyzer (VNA), this microwave-based biosensor achieved a limit of detection (LOD) of 647 CFU/ml. This LOD can be further reduced to 6.47 CFU/ml with a simple preconcentration step prior to the sensing procedure. The sensor has also been tested to detect E. coli in natural water systems with a low-cost, palm-sized portable VNA, suggesting its excellent feasibility for real-time on-site E.coli detection.

Liquid/liquid junction microelectrodes for monitoring cholinergic transmitter in live mice brain in vivo

Acetylcholine (ACh) is an important neurotransmitter and biomarker for neurological disorders. The quantitative detection of ACh in vivo is critical but remains a challenge. In this work, we developed a novel micrometer-sized electrode based on interface between two immiscible electrolyte solutions (ITIES) to achieve in vivo measurement of ACh at high spatiotemporal resolution. The fabricated microITIES electrode was tested in vitro for ACh sensing using electrochemical methods including cyclical voltammetry and i-t amperometry in artificial cerebrospinal fluid (ACSF) solution. An increase in current was observed in both CV and i-t at -0.25 V (vs E1/2, TEA). Both CV and i-t showed a high sensitivity and a linear response with the linear range starting from as low as 0.5 μM. Then the electrode was applied for in vivo measurement of ACh in the living mouse brain. The electrode was implanted in the cortex of the mouse brain via stereotaxic surgery. The electrode was tested for exogenously applied ACh in vivo by local injection of ACh (500 nL, 0.5 M) twice. Repeated cyclic voltammograms were recorded before, during, and after both injections; the cyclic voltammograms showed a significant increase in current at ACh detection potential. The electrode was also tested for endogenously released ACh in vivo by the local injection of a high concentration KCl solution (500 nL and 1000 nL, 100 mM) to stimulate ACh release. Similarly, repeated cyclic voltammograms were recorded before, during, and after both injections; a significant increase in current at the ACh detection potential in the cyclic voltammograms was observed following each injection of KCl. These results validated the capability of the introduced microITIES electrode to measure exogenous and endogenous ACh in vivo.

Electrochemical immunosensor based on poly(5-aminoindole) for cancer biomarker pentraxin-3 detection

Pentraxin-3 (PTX-3) plays a critical role in regulating inflammation, immune response, angiogenesis, and tissue remodeling. As a serum biomarker, it holds a potential in cancer diagnostics and monitoring. Elevated expression of PTX-3 has been found in various cancers, namely lung, prostate, gastric, breast, and hepatic cancers. Here, a PTX-3 immunosensor was fabricated by utilizing poly(5-aminoindole) (P5AIn) to increase the current response and the electroactive surface area (ESA). (3-Aminopropyl)triethoxysilane (APTES) was used as a linker and as an electron transfer enhancer. The developed PTX-3 immunosensor (BSA/anti-PTX-3/APTES/P5AIn/SPCE) shows excellent performance for PTX-3 detection in a wide concentration range from 0.0001 to 2000 ng/mL with the LOD of 0.012 pg/mL. Furthermore, the sensor possessed good reproducibility (%RSD = 0.78), a long shelf-life of at least 4 weeks (% RSD = 0.89), and high specificity to PTX-3. The fabricated PTX-3 immunosensor was demonstrated in the measurement of PTX-3 concentrations in real blood serums from gastric patients. It has been shown as a potentially promising portable sensor for cancer diagnostics and monitoring for cancer patients in remote areas with a low cost.

High-performance electrochemical immunosensor for ultrasensitive detection of malachite green in food matrices using MOF-derived nanocomposites

A highly specific and ultrasensitive electrochemical immunosensor for malachite green (MG) detection in complex food matrices is presented. The sensor was constructed through a stepwise assembly process incorporating gold nanoparticles, antibodies, and metal-organic framework (MOF)-derived Pd/CuO@NiO nanocomposites. Its structure and electrochemical performance were thoroughly validated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Key detection parameters, including pH and nanocomposite concentration, were systematically optimized to maximize sensor performance. The sensor demonstrated a broad linear detection range (10-4 to 100 ng/mL) and an ultralow detection limit (42 pg/L). Specificity tests confirmed the immunosensor's ability to selectively detect MG without interference from structurally similar compounds such as crystal violet, nitrofuran drugs, and chloramphenicol. Its practical applicability was verified using pretreated freshwater fish samples spiked with MG, yielding recoveries of 95%-105%. Furthermore, the results showed strong agreement with those of the conventional enzyme-linked immunosorbent assays (ELISA) method, with minimal difference ratios observed. These findings establish the immunosensor as a reliable, accurate, and rapid tool for detecting MG in food safety applications. Looking ahead, the platform's modular design and versatility provide opportunities to extend its application to other harmful contaminants in food and environmental monitoring, contributing to broader advancements in public health and safety.

Advances and applications of biosensors in pulmonary hypertension

Pulmonary hypertension (PH) is a serious disease characterized by elevated pulmonary artery pressure, with its prevalence and incidence continuously increasing, posing a threat to the lives of many patients worldwide. Due to the complex etiology of PH and the lack of specificity in clinical manifestations, there is currently a lack of effective and specific methods for early diagnosis in clinical practice. Biosensors hold significant promise for the early detection, therapeutic monitoring, prognostic evaluation, and personalized treatment of PH, owing to their rapid, sensitive, and highly selective characteristics. The rapid development of various types of biosensors, such as electrochemical biosensors, optical biosensors, microfluidic biosensors, and wireless biosensors, combined with the use of nanomaterials, makes the rapid and accurate detection of PH-related biomarkers possible. Despite the broad application prospects of biosensors in the field of PH, challenges remain in terms of sensitivity, selectivity, stability, and regulation. This article reviews the main pathophysiological mechanisms and commonly used biomarkers of PH, the types and principles of biosensors, and summarizes the progress of biosensors in PH research as well as the current challenges, in order to promote further in-depth research and the development of biosensor technology, thereby improving the diagnosis and treatment effects of PH. Clinical trial number: Not applicable.

ZIF-67 decorated with silica nanoparticles and graphene oxide nanosheets composite modified electrode for simultaneous determination of paracetamol and diclofenac

In this work, a novel nanocomposite containing zeolitic imidazolate framework-67 decorated silica nanoparticles/graphene oxide nanosheets (ZIF-67/SiO2NPs/GONs) was synthesized and used for the fabrication of the modified glassy carbon electrode for individual and simultaneous electrodetermination of paracetamol (PAR) and diclofenac (DIC) at trace levels. Structural and morphological characterization of the nanocomposite were carried out using suitable techniques. The modified electrode; ZIF-67/SiO2NPs/GONs/GCE, exhibited excellent electrocatalytic activities toward the oxidation of PAR and DIC than the bare GCE, GONs/GCE, SiO2NPs/GONs/GCE and ZIF-67/GCE. Through using differential pulse voltammetry, the individual and simultaneous determination of PAR and DIC were conducted by the ZIF-67/SiO2NPs/GONs/GCE. Under optimal conditions, it has been observed that the calibration plots for PAR and DIC exhibit linearity within the concentration ranges of 0.5-190 (PAR) and 0.5-200 µM (DIC), with detection limits of 0.29 and 0.132 µM for PAR and DIC, respectively. The ZIF-67/SiO2NPs/GONs/GCE shows commendable stability, reproducibility, and repeatability, and the proposed method is evaluated by individual and simultaneous determination of PAR and DIC in real samples with satisfactory results (recovery > 97%).

Logic-gated approach for targeted delivery and site-selective activation of photothermal agents in precision cancer treatment

Logic-gated strategies represent a promising approach to achieving highly selective cancer therapies. In this work, we present LG-AB (Logic-Gated Aza-BODIPY), an OFF-ON photothermal therapy (PTT) agent designed to selectively target cancer cells. LG-AB undergoes a red-shift in its maximum absorbance wavelength when activated in the tumor microenvironment, enabling the molecule to precisely generate heat in the cancerous tissue upon light irradiation. Unlike conventional activatable agents that rely on a single biomarker, LG-AB employs an AND logic-gated design, where glucose transporter 1 (GLUT1) overexpression facilitates targeted cellular uptake in cancer cells, followed by activation through elevated glutathione (GSH) levels. Beyond demonstrating photothermal efficacy in human lung cancer and murine breast cancer cells, we show that LG-AB effectively attenuates cancer progression through heat-induced apoptosis, with minimal off-target effects to surrounding tissues. The versatility of this strategy is further demonstrated through the development and application of LG-CPT (Logic-Gated Camptothecin), which utilizes the same logic-gated design. Our results show that enhancing specificity and limiting collateral damage can be broadly applied across different therapeutic agents.

M3-DPPE Liposomal Nanoparticles Encapsulating CLEC12A Enhance CD206-Mediated Endocytosis and Efficacy in the Collagen-Induced Arthritis Model

OBJECTIVE

This study aimed to investigate the efficacy of M3-DPPE liposomal nanoparticles encapsulated with mRNA encoding cytokines (M3-mRNAs) in targeting macrophages for the treatment of inflammation-induced joint injury.

METHODS

in vitro, M3-mRNAs were administered to peritoneal exudate macrophages (PEMs), and the uptake was assessed using flow cytometry. The mechanism of uptake was investigated by blocking the CLEC12A pathway with M3-SiCLEC12A and observing CD206-mediated endocytosis. In vivo, the distribution of Dir-labeled M3-drugs was monitored using IVIS imaging, and its accumulation in inflammatory and noninflammatory areas was evaluated. The therapeutic potential was evaluated in collagen-induced arthritis (CIA) model mice by assessing macrophage polarization, joint pathology, and cytokine expression.

RESULTS

in vitro studies demonstrated that M3-mRNAs were taken up significantly by PEMs via CD206-mediated endocytosis. In vivo imaging showed that Dir-labeled M3-drugs accumulated predominantly in inflammatory areas and subsequently in bone injury joints. Treatment with M3-drugs in collagen-induced arthritis model mice increased the population of F4/80+ and F4/80+/CD206+ M2 macrophages in inflamed joints, leading to reduced joint fibrosis and modulation of cytokine levels, including decreased pro-inflammatory cytokines (IL-6, IL-1β, TNF-α, and INF-γ) and increased anti-inflammatory cytokines (IL-10 and TGF-β).

CONCLUSIONS

M3-SiCLEC12A enhanced CD206-mediated endocytosis of M3-mRNAs and M3-drugs in macrophages, promoting the production of corresponding proteins and modulating the immune microenvironment. This treatment approach shows promise in repairing inflammation-induced bone and joint injury by balancing pro-inflammatory and anti-inflammatory cytokines. However, further research is required to address drug tolerance and safety concerns and minimize potential side effects before clinical application in autoimmune diseases caused by inflammation.

Application of surfactants in the electrochemical sensing and biosensing of biomolecules and drug molecules

Realizing sensitive and efficient detection of biomolecules and drug molecules is of great significance. Among the detection methods that have been proposed, electrochemical sensing is favored for its outstanding advantages such as simple operation, low cost, fast response and high sensitivity. The unique structure and properties of surfactants have led to a wide range of applications in the field of electrochemical sensors and biosensors for biomolecules and drug molecules. Through the comparative analysis of reported works, this paper summarizes the application modes of surfactants in electrochemical sensors and biosensors for biomolecules and drug molecules, explores the possible electrocatalytic mechanism of their action, and looks forward to the development trend of their applications. This review is expected to provide some new ideas for subsequent related research work.

Surfactant-mediated colorimetric assay assisted with in-situ rolling circle amplification on magnetic beads

Gold nanoparticles (AuNPs) with localized surface plasmon resonance effect have been widely used for colorimetric detection based on the interparticle plasmon coupling during AuNPs aggregation. However, it is still challenging to develop portable and quantitative methods with good sensitivity and excellent selectivity. In this study, a smartphone-based colorimetric assay is developed on the principle of surfactant-mediated AuNPs aggregation assisted with rolling circle amplification (RCA) on magnetic beads (MBs). The detection of adenosine is demonstrated as an example. The cetyl trimethyl ammonium bromide (CTAB) causes the negatively charged AuNPs to aggregate, which results in the color change from red to blue. When adenosine is in solution, the RCA process is triggered on the MBs because of specific adenosine-aptamer recognition, resulting in prolongation of single-stranded nucleic acid (ssDNA). The solution color remains red due to the electrostatic interaction between CTAB and ssDNA. Using this method, the limit of detection (LOD) for adenosine can be as low as 16 pM. Besides, it also works well in human serum. In addition, a portable device integrated with in-situ RGB analysis software is developed for the detection with a smartphone. This study offers a new strategy to improve the sensitivity and selectivity for the AuNPs-based colorimetric assay, taking advantages of specific aptamer recognition, in-situ RCA on MBs, magnetic separation, and smartphone-based portable device.

Chemically engineered unzipped multiwalled carbon nanotube and rGO nanohybrid for ultrasensitive picloram detection in rice water and soil samples

Picloram (4-Amino-3,5,6-trichloro pyridine-2-carboxylic acid) is a chlorinated herbicide that has been discovered to be tenacious and relatively durable in both soil and water. It is known to have adverse and unpleasant effects on humans causing several health complications. Therefore, the determination of picloram is profoundly effective because of its bio-accumulative and persistent nature. Because of this, a sensitive, rapid, and robust detection system is essential to detect traces of this molecule. In this study, we have constructed a novel nanohybrid system comprising of an UZMWCNT and rGO decorated on AuNPs modified glassy carbon electrode (UZMWCNT + rGO/AuNPs/GCE). The synthesized nanomaterials and the developed system were characterized using techniques such as SEM, XRD, SWV, LSV, EIS, and chronoamperometry. The engineered sensor surface showed a broad linear range of 5 × 10^-2 nM to 6 × 10⁵ nM , a low limit of detection (LOD) of 2.31 ± 0.02 (RSD < 4.1%) pM and a limit of quantification (LOQ) of 7.63 ± 0.03 pM. The response time was recorded to be 0.2 s, and the efficacy of the proposed sensor system was studied using rice water and soil samples collected from the agricultural field post filtration. The calculated recovery % for picloram in rice water was found to be 88.58%-96.70% (RSD < 3.5%, n = 3) and for soil it was found to be 89.57%-93.24% (RSD < 3.5%, n = 3). In addition, the SWV responses of both the real samples have been performed and a linear plot have been obtained with a correlation coefficient of 0.97 and 0.96 for rice and soil samples, respectively. The interference studies due to the coexisting molecules that may be present in the samples have been found to be negligible. Also, the designed sensor has been evaluated for stability and found to be highly reproducible and stable towards picloram detection.

Sericin-Based Bio-Inspired Nano-Engineering of Heterometallic AgAu Nanocubes for Attomolar Mefenamic Acid Sensing in the Mobile Phone-Based Surface Plasmon-Coupled Interface

Engineering photo-plasmonic platforms with heterometallic nanohybrids are of paramount significance for realizing augmented sensitivity in fluorescence-based analytical detection. Although myriad nanomaterials with versatile functionalities have been explored in this regard in the surface plasmon-coupled emission (SPCE) interface, light harvesting using nano-antennas synthesized via sustainable bio-inspired routes still remains a high priority in current research. Our study provides a rational design for in situ fabrication of nanoparticles of silver, gold, and their plasmonic hybrids using biocompatible, non-hazardous sericin protein (obtained Bombyx mori) as the reducing and capping agent. The one-pot, user-eco-friendly technology demonstrated here utilizes UV irradiation to promote the photo-induced electron transfer mechanism, thereby yielding nanomaterials of tunable optoelectronic functionalities. The resulting homometallic and heterometallic nanohybrids with robust localized surface plasmon resonances (LSPR) showed strong light-confining attributes when interfaced with the propagating surface plasmon polaritons (SPPs) of the SPCE platform, thereby yielding tunable, highly directional, polarized, and amplified fluorescence emission. The experimentally obtained emission profiles displayed an excellent correlation with the theoretically obtained dispersion diagrams validating the spectro-plasmonic results. The abundant hotspots from AgAu nanocubes presented in excess of 1300-fold dequenched fluorescence enhancement and were utilized for cost-effective and real-time mobile phone-based sensing of biologically relevant mefenamic acid at an attomolar limit of detection. We believe that this superior biosensing performance accomplished using the frugal bioinspired nano-engineering at hybrid interfaces would open new doors for developing nanofabrication protocols with the quintessential awareness of the principles of green nanotechnology, consequently eliminating hazardous chemicals and solvents in the development of point-of-care diagnostic tools.

COF-43 based voltammetric sensor for Ag(I) determination: optimization of experimental conditions by Box-Behnken design

Hydrazone-linked covalent organic framework-43 (COF-43) was synthesized and the carbon paste electrode (CPE) modified with this COF was used as a voltammetric sensor to measure silver(I). Various characterization tests (XRD, FTIR, BET, SEM/EDX, electrochemical impedance (EIS), and cyclic voltammetry (CV)) were performed on the synthesized COF-43 and the prepared COF-43/CPE. Box-Behnken design was used to optimize the preparation and operation conditions of the sensor. EIS and CV investigations reveal the diffusive characteristics of silver transport in the electrode matrix. An appropriate mechanism for the sensor procedure has been suggested and ratified by electrochemical and SEM/EDX techniques. The COF-43 used has several recognition elements for the selective binding of silver ion and due to its high porosity provides a large space for the deposition and reduction of large amounts of silver. Therefore, due to the correct selection of COF used in the construction of the sensor, high selectivity and sensitivity for the prepared sensor has been achieved. The obtained data disclosed that the modification of the carbon paste electrode by COF-43 significantly improves the analytical characteristics of the sensor, which specifies the performance of COF-43 as a sensory material for determining silver(I). The obtained calibration curve is linear in the concentration range from 0.001 μM to 10.0 μM and the detection limit is 1.5 × 10^-10 M. Various statistical tests have been employed to evaluate the sensor performance. The appropriate accuracy and precision of the proposed method were confirmed using the analysis of variance (ANOVA) approach. Potential interferences were investigated and it was found that the other species did not have a significant effect on the sensor performance. The prepared sensor has been successfully used to measure silver in two samples of photographic effluents, bleaching, and fixing agents. The results from the analysis of real samples demonstrate the reliable applicability of the fabricated sensor.

Ultrasensitive Aptasensors for the Detection of Viruses Based on Opto-Electrochemical Readout Systems

Viral infections are becoming the foremost driver of morbidity, mortality and economic loss all around the world. Treatment for diseases associated to some deadly viruses are challenging tasks, due to lack of infrastructure, finance and availability of rapid, accurate and easy-to-use detection methods or devices. The emergence of biosensors has proven to be a success in the field of diagnosis to overcome the challenges associated with traditional methods. Furthermore, the incorporation of aptamers as bio-recognition elements in the design of biosensors has paved a way towards rapid, cost-effective, and specific detection devices which are insensitive to changes in the environment. In the last decade, aptamers have emerged to be suitable and efficient biorecognition elements for the detection of different kinds of analytes, such as metal ions, small and macro molecules, and even cells. The signal generation in the detection process depends on different parameters; one such parameter is whether the labelled molecule is incorporated or not for monitoring the sensing process. Based on the labelling, biosensors are classified as label or label-free; both have their significant advantages and disadvantages. Here, we have primarily reviewed the advantages for using aptamers in the transduction system of sensing devices. Furthermore, the labelled and label-free opto-electrochemical aptasensors for the detection of various kinds of viruses have been discussed. Moreover, numerous globally developed aptasensors for the sensing of different types of viruses have been illustrated and explained in tabulated form.

Unprecedented 2D GNR-CoB nanocomposite for detection and degradation of malachite green - A computational prediction of degradation pathway and toxicity

In the present work, we have synthesized a novel 2D GNR-CoB composite and was applied it for electrochemical sensing and photocatalytic degradation of the malachite green (MG). The physicochemical properties of the 2D GNR-CoB were analyzed using X-ray diffraction, Transmission electron microscopy, Energy dispersive X-ray diffraction which depicts the morphological and crystalline nature of the prepared composite. The pencil graphite electrode modified with 2D GNR-CoB composite showed excellent electrochemical response for MG detection with a LOD of 1.92 nM, linear range of 25-350 nM with a high sensitivity of 1.714 μA μM^-1 cm^-2. Besides, the 2D GNR-CoB modified PGE exhibited good recovery for the detection of MG in real samples such as green peas and lady's fingers. Furthermore, the 2D GNR-CoB modified electrode showed excellent photocatalytic activity for the degradation of MG. It suggests that under visible light, GNR-CoB material generates superoxide (·O₂^-) and hydroxyl (·OH) radicals for MG degradation. The prepared composite showed an efficiency of 91.28% towards the degradation of MG. Based on the experimental analysis and density functional theory calculations, a photocatalytic degradation mechanism pathway for MG is proposed. A quantitative structure-activity relationship study was used to examine the toxicity of the degradation intermediates.

Nano-Bio-engineered Silk Matrix based Devices for Molecular Bioanalysis

Silk is a fibrous protein, has been a part of human lives for centuries and was used as suture and textile material. Silk is mainly produced by members of certain arthropods such as spiders, butterflies, mites, and moths. However, recent technological advances have revolutionized silk as a biomaterial for various applications ranging from heat sensors to robust fibers. The biocompatibility, mechanical resilience, and biodegradability of the material make it a suitable candidate for biomaterials. Silk can also be easily converted into several morphological forms, including fibers, films, sponges, and hydrogels. Provided these abilities, silk have received excellent traction from scientists worldwide for various developments, one of them being its use as a bio-sensor. The diversity of silk materials offers various options, giving scientists the freedom to choose from and personalize them as per their needs. In this review, we foremost look upon the composition, production, properties, and various morphologies of silk. The numerous applications of silk and its derivatives for fabricating biosensors to detect small molecules, macromolecules, and cells have been explored comprehensively. Also, the data from various globally developed sensors using silk have been described into organized tables for each category of molecules, along with their important analytical details. This article is protected by copyright. All rights reserved.