Methanol (MeOH) is widely used in industry and is highly toxic when ingested. In this work, a new micro-conductometric transducer is functionalized with magnetic Fe3O4 nanoparticles capped with Artemisia Herba Alba (AHA) extract. The resulting AHA-Fe3O4 nanoparticles, crystallized in the cubic spinel phase, exhibit an average crystallite size of 6 nm. These nanoparticles were homogeneously dispersed within an electrodeposited chitosan film on interdigitated electrodes for conductometric measurements. The gas-sensing behavior of the films was evaluated at room temperature toward methanol, ethanol, and acetone vapors. For methanol, the sensor shows response times (tRes) ranging from 9 to 12 s depending on the analyte concentration, with a detection limit of 600 ppm in the gas phase. The methanol sensor presents a sensitivity 30 times lower for acetone and 3.7 times lower for ethanol. The sensor exhibited stable detection sensitivity over two months, under intermittent storage at 4 °C. Methanol was detected in the headspace of commercial product samples, in good agreement with the producer’s value.

A portable colorimetric sensing system has been developed using a glass substrate immobilized with Chrome Azurol S (CAS)-iron (III) complex for rapid and selective detection of organophosphate antiscalant, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) in water system. Owing to its higher affinity for Fe3+, PBTC removes Fe3+ from the CAS-Fe3+ complex, resulting in a distinct color change from blue to orange. Initially, a solutionbased colorimetric assay was studied. The finding showed that at CAS-Fe3+:PBTC ratio of 1:6, a linear response is achieved in the concentration range of 1-10 ppm, with a low detection limit of 2.25 ppm. Negligible interference was observed from other common anionic antiscalants, e.g., acrylic acid-2-acrylamido-2-methylpropane sulfonic acid copolymer, and poly(methacrylic acid), including small anionic molecules (e.g., phosphate, bicarbonate, and sodium dodecyl sulfate), confirming its selectivity. The CAS-Fe3+ complex was then immobilized on a glass surface, yielding a blue glass surface. Results from UV-Vis spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy analyses confirmed the successful modification of the glass's surface. In practical usage, the prepared portable sensor was simply immersed into the PBTC solutions including real samples from industrial water. Visual color change combining with the significant reduction in UV-Vis absorbance showed good correlation with PBTC concentration in the range of 5-25 ppm and validated the sensor's capability for PBTC detection in real samples. The developed CAS-Fe3+ glass sensor provided a rapid, cost-effective, and portable approach for real-time PBTC monitoring in industrial water systems, offering a practical tool for water quality control and environmental assessment.

Polydopamine-based molecularly imprinted electrochemical microsensors have been developed as a novel, rapid, and selective detection of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC), a key orthophosphate compound used as a corrosion inhibitor in industrial cooling water systems. Monitoring PBTC levels is essential to optimize operational efficiency and ensure environmental protection. The microsensor was fabricated via an in situ electropolymerization process, where polydopamine served as a matrix material, providing high specificity and stability. Fourier-transform infrared (FTIR) spectroscopy and cyclic voltammetry (CV) results confirmed the effective structure and functionality of the microsensors. Under optimal conditions, the device exhibited a strong correlation between the CV and electrochemical impedance (EIS) signals and the PBTC concentrations ranging from 1 to 30 ppm, enabling high-accuracy measurements with a low detection limit. The selectivity was confirmed by measuring synthetic samples of mg/L-level PBTC in phosphate-buffered saline, which possesses a phosphate functional group interference. The microsensor also showed a regeneration capability, with the precisions (relative standard deviations, RSD, n = 2) of 8.10 %. Considering the advantages of easy fabrication and detection performance, this innovative approach offers a powerful, cost-effective, and user-friendly solution for PBTC detection in real samples, positioning the microsensor as a new tool for diverse applications in environmental monitoring and industrial process control.

SPR (surface plasmon resonance) biosensor-based analytical methods enable rapid, straightforward, and cost-effective detection of DNA oligonucleotides. However, the detection limits of currently available SPR biosensors for BCR-ABL gene oligonucleotides remain too high to reliably detect sub-nanomolar concentrations. This study presents a new signal-enhancement approach for SPR DNA biosensors based on a gold nanoparticle (AuNP) sandwich assay. In this work, we demonstrated that AuNP-modified oligonucleotides can serve as labels that significantly amplify the SPR biosensor response in a sandwich-type SPR DNA biosensor. The analytical characteristics of the developed AuNP-labeled biosensor for detection of BCR-ABL fusion gene oligonucleotides were studied. The AuNP-labeled biosensor exhibited a detection limit of 80 pM, which is significantly lower than that of a traditional label-free SPR biosensor (50 nM). The measurement error for BCR-ABL target detection was significantly lower with the AuNP-labeled biosensor than with the label-free SPR biosensor. The conditions of synthesis of AuNPs by citrate reduction of AuCl3 that allow the monodisperse size distribution and absence of AuNP aggregation were established as well. Based on the obtained data, we conclude that a sandwich assay employing AuNP-modified oligonucleotides as labels is a promising approach for the highly sensitive detection of genetic markers. The developed AuNP-labeled DNA biosensing approach can be adapted to enhance the signal in other DNA hybridization-based SPR biosensors.

Biosensors based on field-effect transistors (FETs) are currently undergoing significant technological advances and structural optimizations, favoring their deployment in multiple fields, particularly in health monitoring and diagnostics. Their remarkable performance, particularly in terms of specificity, response speed, real-time analysis capability, low cost, miniaturization potential, and portability, explains the growing interest they attract. This article provides an in-depth review of the different types of FET biosensors, gate configurations, operating modes, detection mechanisms, and key characteristics. It also presents recent advances, emerging biomedical applications, as well as the current limitations and technological challenges associated with these devices.

Enterotoxigenic Escherichia coli (ETEC) is a pathogenic strain of E. coli, which is transmitted via food and water, primarily causing diarrhea in children below 5. Due to similar biochemical properties, conventional culture and biochemical identification methods are unsuitable for distinguishing ETEC. Immunoassay and molecular detection are alternative techniques for detecting ETEC, which target heat-labile (LT) and heat-stable (ST) enterotoxins. However, they may require specialized equipment, and some methods may require a pre-enrichment process, making them unsuitable for rapid and on-site detection. This study designs a DNA-based electrochemical biosensor, specifically for detecting the heat-labile toxin (LT) gene of ETEC. The screen-printed electrode (SPE) was functionalized with diazonium salt and immobilized with an aminated-LT probe, which was confirmed by Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). This biosensor showed high efficiency in determining ETEC's DNA in the range of 1.9 × 10-8 μg/mL -1.9 μg/mL with a limit of detection (LOD) of 1.9 × 10-8 μg/mL. The developed biosensor exhibited high specificity without cross-reaction with other foodborne pathogenic bacteria, including Shigella dysenteriae, Salmonella Typhi, and E. coli ATCC25922. Moreover, this biosensor was challenged with spiked samples, prepared by the standard addition method, which demonstrated good performance, represented by good accuracy (Recovery >90%) and precision (coefficient of variation or COV < 10%). This is a promising technology that has the potential to be further developed as a point-of-need for medical diagnosis and epidemiological surveillance.

Background Orthophosphate contamination is a critical environmental issue due to its role in eutrophication, which disrupts aquatic ecosystems and degrades water quality. Developing efficient and sustainable removal strategies is essential to mitigate these impacts. Among various approaches, adsorbent materials have garnered significant attention for their ability to effectively capture and remove orthophosphate from water. However, challenges remain in optimizing their efficiency, regeneration, and large-scale applicability. Methods This review explores recent advancements in orthophosphate adsorption technologies, categorizing adsorbents into natural and biogenic materials, synthetic and engineered materials, activated carbon and carbon-based materials, and metal oxide and metal-based adsorbents. A comprehensive evaluation of adsorption mechanisms, material properties, and regeneration potential is provided to assess their feasibility for real-world applications. Significant Findings This analysis identifies promising materials with enhanced adsorption performance and reusability, contributing to cleaner water solutions. By highlighting key research gaps and future directions, this review aims to drive innovation in adsorbent technologies for more effective and sustainable orthophosphate removal.

Paraquat (PQ) is a highly toxic herbicide that has been prohibited in almost 70 countries, but remains in use worldwide. Thus, routine on-site PQ monitoring is a key mechanism to ensure safety and efficiently enforce regulations. Herein, a label-free portable electrochemical aptasensor for the detection of PQ was developed by utilizing aptamer designed to specifically recognize PQ. The aptasensor employs square-wave voltammetry (SWV) to quantify PQ binding on the aptamer-functionalized electrode surface by tracking the downstream oxygen reduction reaction. It provided a detection range spanning from 0.01 to 100.0 mu g mL(-)(1) PQ with a limit of detection (LOD) of 8.9 ng mL(-)(1). Validation against spiked tap water, pomegranate juice, and orange juice revealed recovery rate performances of 75 %-130 %. The aptasensor demonstrates promising feasibility for PQ detection in real-world applications, offering remarkable portability and operational simplicity. Notably, it can operate without supplementary redox agents, requiring only sample incubation and subsequent washing steps.

The disadvantage of single-sine electrochemical impedance spectroscopy (EIS) compared to multi-sine methods is the long measurement duration. This publication presents a method called optimized frequencies EIS (OFEIS) for shortening the measurement duration applicable to electrochemical interfaces that can be described by the Randles circuit. This method is based on an iterative curve analysis during the measurement process and a subsequent circular fitting in the Nyquist plot. The method is analyzed using simulated data and measurements with ion-sensitive field-effect transistors (ISFETs). In the pH measurements carried out with ISFETs, OFEIS only required an average of approx. 64% of the measurement duration in relation to 30 logarithmically distributed frequency points between 10 Hz and 100 kHz. For this, approx. 10-11 measuring points are used and an average absolute percentage error of 2.2% is achieved when determining the charge transfer resistance.

The consumption of illicit drugs is spread worldwide and remains a challenge for concerned authorities. Hence, it is vital to develop effective and precise methods for detecting these types of compounds in biological fluids, seized street samples, and wastewaters. Electrochemical sensors are extensively used for analysis in many fields and represent an exclusive prospect to permit inexpensive, fast, and accurate monitoring and detection simultaneously. Electrochemical approaches are mainly open to forensic investigation because of their high performance in turbid and complex matrices. In this minireview, recent electrochemical strategies applied to the detection of illicit drugs in different samples have been presented.

Acute lymphoblastic leukemia (ALL) represents the most common type of cancer in the pediatric population. The (1;19)(q23;p13) translocation is a primary chromosomal abnormality present in 3–12% of ALL cases. The current study aims to develop a label-free innovative nanodevice for the ultrasensitive diagnosis of the TCF3-PBX1 chimeric oncogene, featuring simplified operation and rapid analysis using minimal sample volumes, which positions it as a superior alternative for clinical diagnostics and early leukemia identification. The biosensor system was engineered on a nanostructured platform composed of polypyrrole (PPy) and a novel chemically functionalized hybrid nanocomposite of platinum nanospheres and titanium dioxide nanoparticles (TiO2@Pt). Single-stranded oligonucleotide sequences were chemically immobilized on the nanoengineered transducer to enable biospecific detection. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ultraviolet-visible spectroscopy (UV-Vis), and atomic force microscopy (AFM) were used to characterize each stage of the biotechnological device fabrication process. The analytical properties of the sensing tool were explored using recombinant plasmids containing the TCF3-PBX1 oncogenic sequence and clinical specimens from pediatric patients with B-cell ALL. After exposing the molecular monitoring system to the genetic target, significant variations were observed in the voltammetric oxidation current (∆I = 33.08% ± 0.28 to 124.91% ± 17.08) and in the resistance to charge transfer (ΔRCT = 19.73% ± 0.96 to 83.51% ± 0.84). Data analysis revealed high reproducibility, with a relative standard deviation of 3.66%, a response range from 3.58 aM to 357.67 fM, a detection limit of 19.31 aM, and a limit of quantification of 64.39 aM. Therefore, a novel nanosensor for multiparametric electrochemical screening of the TCF3-PBX1 chimeric oncogene was described for the first time, potentially improving the quality of life for leukemic patients.

NT-proBNP is the gold standard biomarker for early diagnostics of heart failure, disease prevention, and stratified and individualized patient care. In this work, we aim to develop a novel ultra-sensitive immunosensor for direct NT-proBNP detection in human artificial saliva (AS), which represents an intriguing biological matrix potentially rich in biomarkers. The immunosensor will enhance the sensitivity of detection, reduce measurement time, and enable the simultaneous detection of various biomarkers. The developed biosensor, based on gold working microelectrodes (WEs), was biofunctionalized using 4-carboxymethyl aryl diazonium (CMA) to immobilize anti-NT-proBNP antibodies. The deposition of CMA onto the gold surface of the microelectrodes was accomplished using cyclic voltammetry (CV). The binding between NT-proBNP antibodies and NT-proBNP antigens was tracked using electrochemical impedance spectroscopy (EIS) in conjunction with the standard addition method. A linear detection response within the range of 1–20 pg/mL for NT-proBNP detection in PBS and artificial saliva was demonstrated, with good selectivity in the presence of other potential interfering biomarkers (interleukin 6 (IL-6), interleukin 10 (IL-10), and interleukin 1 β (IL-1β)). The developed immunosensor shows great promise for rapid and accurate analysis in biomedical applications.

The need for fast, efficient, and cost-effective test systems for antibiotics is surging, to control resistant bacterial strains. Electrochemical biosensors offer a good alternative to routine laboratory-bound analytical methods. These biosensors are portable, suitable for in-field analysis and biocompatible for detection of small biomolecules. The aim of this work is the ciprofloxacin active pharmaceutical ingredient since resistance of bacteria to this antibiotic is reportedly increasing worldwide, especially in Lebanon where hospitalization bills are no longer affordable. So, the target is ciprofloxacin detection, a fluoroquinolone antibiotic, on screen-printed electrodes. Following diazonium salt, also known as carboxymethylaniline (CMA) deposition, a ciprofloxacin oligonucleotide was incubated on the electrode. This aptamer acts as an anchor for the ciprofloxacin molecule, allowing the latter’s attachment to the electrode and its quantification. Electrochemical characterization, through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) allowed for deposition of molecules on electrodes and confirmation that an electrochemical change took place. Scanning Electron Microscope images are used to confirm conformational changes on the surface of electrodes. Impedance results reported a limit of detection of LOD = 3 nM, a dynamic range from 10 nM to 100 µM, and reproducibility of results between two aptasensors to be 10

Human Papillomavirus (HPV) is an often asymptomatic widespread sexually transmitted infection responsible for causing various health issues. Low-risk HPV primarily causes genital warts. High-risk HPV types are associated with several cancers, including cervical, anal, and oropharyngeal cancers, posing significant health risks. In this work, we developed an electrochemical biosensor for the detection and differentiation of HPV genotypes based on electropolymerized polypyrrole (PPy) and PAMAM dendrimer-coated gold nanoparticles (PAMAM-AuNPs) for the immobilization of a DNA probe for detecting different HPV genotypes. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and atomic force microscopy (AFM) were used to characterize the biosensor. AFM analysis revealed varied topographic surfaces associated with the increased peaks concerning the biosensor and against patient samples. Electrochemical responses indicated that the genosensor could detect HPV using plasmid (HPV 6, 16, 18, 31, and 33) and cDNA samples (HPV 6, 18, and 31) from infected patients. Different electrochemical profiles were obtained between high-risk and low-risk genotypes. The sensor presented an excellent analytical performance, presenting a lower LOD of 0.04 pg.mu L- 1 and 0.34 pg.mu L- 1 for plasmidial and cDNA samples, respectively. Electrochemical analysis pointed out the ability of the developed genosensor platform to differentiate the HPV genotypes. The proposed biosensor is a promising tool for detecting and monitoring HPV and related diseases such as cervical cancer.

Lung cancer remains one of the deadliest cancers worldwide, which highlights the urgent need for new diagnostic tools to detect reliable biomarkers. To enable scalable and cost-effective production, we developed reusable PDMS stamps patterned with electrodes to print flexible electrodes on PET substrates using a microcontact printing (µCP) approach. PET was chosen not only for its flexibility but also as a more sustainable alternative to conventional rigid materials. On these electrodes, three sensing platforms were tested for neuron-specific enolase (NSE) detection: APTES-based monolayers, electrospun PVA/alginate nanofibers, and electropolymerized polypyrrole (PPy) films. Voltammetric and fluorescence/AFM analyses confirmed that all three platforms could recognize the target analyte, with the PPy-CdTe configuration showing the strongest signal variation. Impedance spectroscopy further supported this finding, revealing a clear linear correlation between charge transfer resistance (RCT) and NSE concentration. The PPy-CdTe sensor demonstrated high sensitivity and consistent performance for NSE detection, achieving a detection limit (LOD) of 8.05 pg·µL−1 and a quantification limit (LOQ) of 26.84 pg·µL−1.

Tumor Necrosis Factor-alpha (TNF-α) is a pro-inflammatory cytokine strongly associated with the early onset and progression of heart failure (HF). In this study, we present the design and fabrication of a label-free, fluorescence-based biosensor for the detection of TNF-α cytokines. The biosensor is constructed using microcontact printing (μCP) to pattern Triethoxysilylundecanal (TESUD) on oxygen plasma-activated polydimethylsiloxane (PDMS) substrates, forming self-assembled monolayers (SAMs) of microstructures. TNF-α antibodies are then covalently immobilized via imine coupling. Detection of TNF-α cytokines at 50 µg/mL was achieved via an optical “sandwich” immunoassay with rhodamine-labeled secondary antibodies, enabling visualization by fluorescence microscopy. Surface wettability analysis confirmed successful stepwise functionalization, while imaging revealed well-defined microstructures and specific immune binding of TNF-α. This platform demonstrates a proof-of-concept and offers a non-invasive, sensitive, and cost-effective alternative for the early detection of TNF-α in biological fluids, with potential applications in HF monitoring.

The employment of nanoparticles to develop systems to deliver drugs and to carry small as well as large therapeutic drugs is a speedily growing research area. The benefits of consuming proteins for preparing to deliver drugs comprise their plentifulness in natural sources, biodegradability, biocompatibility, simple preparation process, as well as economical. Protein nanoparticles have no prospective toxicity, accumulation, large dimensions, or fast clearance out of body. Additionally, they propose the prospect to modify their surface by conjugating them with different ligands. This allows desired delivery to targeted organ or tissue that further decreases systemic toxicity. They are proved to be a better substitute to plan and advance pharmacokinetic and pharmacodynamic properties regarding diverse drug molecules. Herein, while focusing on the different proteins derived from different sources, a summary of nanoparticles, based on proteins, for drug delivery was presented. Several methods to prepare these nanoparticles were described along with their properties and their appropriate design through surface functionalization by conjugation it with various ligands. Potential applications of protein nanoparticles to deliver various kinds of therapeutic agents are summarized in table. It then critically compares protein nanoparticles with other organic nanoparticles used for drug delivery by mentioning limitation. Conclusions and future perspectives add some factors that are significant to design such nanoparticles for useful system to deliver drugs.

The electrochemical impedance spectroscopy (EIS) is a measurement method for characterizing bio-recognition events of a sensor, such as field-effect transistor-based biosensors (BioFETs). Due to the lack of portable impedance spectroscopes, EIS applies mainly in laboratories preventing application-oriented use in the field. This work presents a portable impedance analyzer (PIA) providing a 4-channel EIS of BioFETs. It performs the analysis of the recorded spectra by determining the charge transfer resistance Rct with a power-saving algorithm. Therefore, a circle is fitted into the Nyquist representation of the Randles circuit, from whose zero crossings Rct can be determined. The introduced algorithm was evaluated on 100 simulated spectra of Randles circuits. To analyze the overall system, an adjustable reference circuit was developed that simulates configurable Randles circuits. Additional measurements with pH-sensitive ion-sensitive field-effect transistors (ISFETs) demonstrate the application of the measurement system with electrochemical sensors. Using simulated spectra, the circular fitting is able to detect Rct with a median accuracy of 1.2% at an average nominal power of 40 mW and 3054 µs computing time. The PIA with the embedded implementation of the circuit fitting achieves a median error for Rct of 4.2% using the introduced Randles circuit simulator (RCS). Measurements with ISFETs show deviations of 6.5 ± 2.8% compared to the complex non-linear least squares (CNLS), but is significantly faster and more efficient. The presented system allows a portable, power-saving performance of EIS. Future optimizations for a specific applications can improve the presented system and enable novel low-power and automated measurements of biosensors outside the laboratory.

Nanocomposites made of tetrahexyloxy-substituted Co or Cu phthalocyanines adsorbed onto reduced graphene oxide (rGO) have been prepared for detection of volatile organic compounds (VOCs). Such nanocomposites could be formed in organic solvents, thanks to the high solubility of the substituted phthalocyanines, establishing van der Waals and π-π stacking interactions with rGO. UV-visible, FT-IR, and XPS characterizations evidenced the energy transfer between rGO and the phthalocyanines; this adsorption ability is highly suitable to form nanocomposites exhibiting improved electronic properties. The gas sensing properties of various VOCs were explored by conductometric measurements conducted on interdigitated electrodes modified with the nanocomposites, highlighting the effect of the alkyloxy substituents and phthalocyanine's metal. All exhibited high affinity to ammonia gas compared with other VOCs. The CuPc/rGO nanocomposites showed higher sensitivity with a lower limit of detection (0.4 ppm) compared to CoPc/rGO (1 ppm), while phthalocyanines alone give lower sensitivity, where the limit of detection of CuPc(OHex)4 is 5.7 ppm and CoPc(OHex)4 shows a nonlinear fit. We explained this behavior by improved energy transfer between rGO and CuPc(OHex)4, favoring the coordination of ammonia. Detection of ammonia gas in real samples has been achieved to further demonstrate the efficiency of these sensors.