Detecting toxicants in aquatic ecosystems is critical for assessing the impact of pollutants on the environment. Conventional chemical analysis methods are often time-consuming and resource-intensive, and may not fully capture bioavailability or cumulative pollutant effects. Whole-cell biosensors offer a rapid, biologically relevant method for assessing environmental toxicity. Building on the previous generation of our fiber-optic biosensor, this study introduces a second-generation system that improves usability and field readiness while maintaining the core functionality of the original design. The upgraded system incorporates additional features to enhance portability and ease of deployment in remote environments such as an improved, lightproof case as well as a sustainable power supply incorporating an internal power station as well as solar panels. At its core is a photomultiplier tube (PMT) that quantitively detects low-intensity blue light emitted by bioluminescent bacterial bioreporters, that were immobilized within a calcium alginate matrix on fiber-optic tips, in response to toxicants. As a proof of concept, on-site toxicity measurements of water and sediment samples were conducted at potentially contaminated locations across Israel. Preliminary results obtained with the new configuration indicate notable improvements in operational efficiency and ease of deployment compared to earlier prototypes, while retaining its capabilities in detecting various toxicants as revealed by a complementary chemical analysis. This new configuration offers promising potential as a high-throughput versatile tool for on-site environmental toxicity screening.

A light-addressable potentiometric sensor (LAPS) is a type of bio-sensor based on the semiconductor field effect and modulated light, driven by the advantages of a wide detection range, low fabrication costs, support for miniaturization, etc. The conventional LAPS data processing methods rely on I-V characteristic curves, where a wide bias voltage range (over 1 V) is required to achieve a complete I-V curve, including the accumulation, depletion, and inversion regions in a single measurement process. The wide bias voltage range places high demands on the power supply of the measurement system and is not conducive to miniaturization. In this paper, a novel data processing method for LAPSs based on Gaussian fitting is proposed, and the pH sensing effect of the sensor under this method is investigated. Under the new data processing method, the linearity of the LAPS was 98.2%, the sensitivity was 5.378 points/pH, and the average repetition rate was 1.27%, where the bias voltage range was 0.07 V. The experimental results showed that the new data processing method could help the LAPS to obtain an acceptable pH sensing effect and a narrower bias voltage range compared with these properties for a LAPS operating using the traditional data processing methods. The data processing method based on Gaussian fitting shows the potential to be applied to the design of low-power, miniature LAPSs.

Introduction: Prostate cancer (PCa) represents the second most commonly diagnosed cancer in men worldwide. This cancer is the most frequently diagnosed and the third cause of cancer-related deaths [1-3]. It is of vital importance to diagnose this cancer early to implement an effective treatment [4-5]. The present work reports an electrochemical immunoplatform based on magnetic microbeads (MBs) to determine epithelial extracellular vesicles (EpEVs) applied to PCa diagnosis.

Methods: Our method employs magnetic microparticles (MBs) as an immobilization platform. In an immune-electrochemical system, MBs enhance sensitivity through efficient capturing, analyte concentration, and easy washing in the presence of an external magnetic field. So far, no reported proposed sensor has been developed to detect EpCAM + extracellular vesicles (EVs) in diagnosing PCa. Hence, we report an electrochemical sandwich-type bioassay for assessing EpCAM + EVs in the early stages of PCa. Through the immobilization of the capture antibody (monoclonal anti-EpCAM) on HOOC-MBs, its incubation with EVs and a specific biotinylated detector antibody (anti-CD81) labeled with a streptavidin horseradish peroxidase (strep-HRP) polymer are observed. The amperometric detection of the affinity reaction was performed using disposable screen-printed carbon electrodes (SPCEs) and the hydroquinone (HQ)/H₂O₂ system.

Results: The detection limits for the proposed method and the ELISA test were 0.4 ng µL⁻¹ and 5 ng µL⁻¹, and the intra- and inter-assay coefficients of variation were below 3.81% and 6.54%, respectively.

Conclusions: Our electrochemical immunoplatform offers an interesting analytical tool for PCa diagnosis and prognostics.

References:

[1] doi: 10.3322/CAAC.21660.

[2] doi: 10.1002/IJC.29538.

[3] doi: 10.1016/J.EUF.2015.01.002.

[4] doi: 10.1016/J.BIOS.2017.11.029.

[5] doi: 10.1007/S00604-019-3410-0.

Water pollution remains one of the most pressing global environmental challenges, posing significant threats to ecosystems, human health, and biodiversity. Among the various pollutants, heavy metal contamination is particularly concerning, even at trace concentrations, due to its bioaccumulative and toxic effects. The efficient detection of heavy metals is essential for effective environmental monitoring and public health protection. Electrochemical sensors have emerged as promising tools for heavy metal detection, offering high sensitivity, selectivity, and accuracy alongside operational flexibility.

This study presents the development of an advanced electrochemical sensor based on polyaniline (PANI) incorporated into a sodium alginate (SA) matrix. Sodium alginate, a natural polymer, is notable for its excellent ion exchange properties and acid stability, making it an ideal candidate for composite materials. Blending alginate fibers with conducting polymers like PANI creates materials with enhanced functional properties suitable for advanced applications.

The PANI/SA composite was synthesized via in situ polymerization, improving the material's electrical conductivity and mechanical stability. The composite was then employed to modify a glassy carbon electrode, creating a robust electrochemical sensor for the sensitive detection of heavy metals such as lead (Pb) and cadmium (Cd). This sensor combines the high electrical conductivity of PANI with the biocompatibility and gel-like properties of SA, resulting in a highly efficient detection platform. The PANI/SA sensor demonstrated exceptional sensitivity, stability, and rapid response times, with low detection limits for Pb and Cd, showcasing its potential for real-world environmental applications.

Agriculture and food systems go hand in hand, so proper farm management is necessary for ensuring global sustainability and food security. The impact of agricultural practices on production is direct, affecting all stages from germination to post-harvest treatment. Farmers who adopt structured management practices tend to increase their yields and profitability. In recent years, research on nanobiosensors has gained notable relevance, since nanostructures of nanometer size present unique properties that distinguish them from regular versions. Nanomaterials are being tested as potential candidates for transducer coatings that can accurately detect picomolar levels. This study was carried out through a systematic review of the available and updated literature on the incorporation of nanobiosensors in agronomy and agriculture. Nanobiosensors can be applied pre- and post-harvest and are easily portable and low-cost; thus, they allow for rapid on-site assessment of crop and soil health and detect biotic and abiotic stresses, nutritional status, and the presence of contaminants and spoilage indicators. Moreover, early detection of damage can prevent crop losses and avoid yield losses caused by the impact of stress. The combination of these biological sensors with nanomaterials amplifies the signal, increasing sensitivity and reducing the detection limit. Being highly selective, they enable the early detection and management of anomalies in agricultural production. This study analyzes recent novelties and existing limitations and discusses the structure and types of nanobiosensors in terms of their application in the agricultural sector.

This presentation highlights the use of an emerging electrochemical biomembrane sensor for the (bio)membrane activity assessment of nanomaterials/advanced materials. It utilizes a self-assembled dioleoyl phosphatidylcholine (DOPC) monolayer on a fabricated microHg-on-Pt chip electrode to generate characteristic rapid cyclic voltammograms (RCV) at 40 Vs^-1. These RCVs contain current peaks due to underlying phase transitions in response to the applied electric field. Changes in the RCV scan and associated capacitance peaks in the presence of (bio)membrane active substances are related to membrane disruption, detailing the nature and extent of the interactions. These interactions will be related to the MIE (molecular initiating event) of each species, providing insight into the mechanism of their interaction with the biomembrane-like sensor layer. Extracting membrane affinity parameters from the data enables the estimation of the structure–activity relationships (SARs) of the materials with the sensing layer. The biomembrane sensor has successfully been intercalibrated with in vitro analysis through MTT assays using colchicine, methyl methane sulfonate and chlorpromazine and exhibited more than ten times higher sensitivity. This unique advanced material screening technology, the results and their analysis will be presented at this conference.

The BIO-SUSHY project is funded by the European Union under Grant Agreement Number 101091464. The University of Leeds is funded by the UKRI Horizon Europe Guarantee Fund, Grant Number 10056199. The views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HaDEA).

The integration of nanotechnology in biosensor development has unlocked new possibilities for highly sensitive and selective molecular detection. Nanomaterials exhibit exceptional electrical, catalytic, and structural properties that can be tailored to optimize biosensor performance. This presentation examines how engineered nanostructures and smart surface modifications enhance biosensor performance. Traditional enzyme-based biosensors were compared with integrated nanomaterial designs, optimizing enzyme immobilization and detection method parameters for the best stability and selectivity. For nanomaterial-based sensors, functionalization with graphene (G), carbon nanotubes (CNs), and NiCo₂O₄ improved charge transfer and catalysis, while chemically and biologically synthesized gold nanoparticles (AuNPs) were evaluated for enzyme-mimetic (nanozyme) and antioxidant properties.

Nanomaterial-functionalized biosensors demonstrated significant improvements in sensitivity and detection limits. A glucose oxidase-based biosensor utilizing a layer-by-layer self-assembly approach with G-CN composites achieved a low operational potential of -0.2 V vs. Ag/AgCl and a detection limit of 41 µM. Thyroxine detection was enhanced by incorporating NiCo₂O₄ on graphene oxide platforms, reducing the detection limit from 23 nM to 6.1 pM. Furthermore, biosensors leveraging the peroxidase-like activity of AuNPs enabled efficient oxidative stress detection via H₂O₂ quenching. Notably, biologically synthesized gold nanoparticles (Bio-AuNPs) preserved the intrinsic antioxidant properties of plant extracts, offering a sustainable and biocompatible alternative for biosensing applications.

The integration of nanostructured materials and smart surface engineering has significantly advanced biosensor technology, demonstrating superior analytical performance and real-sample applicability. These findings highlight the potential of nanomaterial-based biosensors for next-generation point-of-care diagnostics, paving the way for highly efficient, biocompatible, and sustainable sensing platforms.

References:

[1] M. David et al., Sens. Actuators B Chem. 255 (2018) 3227-3234

[2] M. David et al., Bioelectrochemistry 129 (2019) 124–134

[3] M. David et al., J. Electroanal. Chem 911 (2022) 116240

[4] M. David et al., Pharmaceuticals 2024, 17(9), 1105

Introduction:

Traditional protein sequencing methods, such as mass spectrometry, struggle with novel protein variants, isoforms, and the precise locations of post-translational modifications (PTMs). We propose a graphene-based sensing platform for single-point amino acid and PTM analysis, utilizing graphene field-effect transistors (GFETs) to capture the distinct electrochemical fingerprints of amino acids and their modifications.

Methods:

We modeled the electrochemical dynamics of amino acids during pH titration [1], leveraging their amphoteric nature to generate unique charge and capacitance profiles measured using GFETs. To validate our model, we started with optimizing a functionalization protocol for directional amino acid attachment to graphene, monitored via surface plasmon resonance (SPR). We developed three platforms to enable the process in GFETs: one for sensor preconditioning, another for functionalization with amino acids and peptides, and a third for pH titration-based amino acid fingerprint analysis using GFETs.

Results:

The coupling reactions with the graphene linker and directional amino acid attachment were monitored with single-layer precision. SPR results showed the regulation of the number of molecules, ensuring reproducible surface density control critical for the analysis of surface potential measurements. The functionalization chemistry also enables in situ peptide synthesis on graphene. Additionally, our platforms function effectively in both aqueous and organic solvents, and the Dirac point of graphene has been tracked in different conditions.

Conclusion:

This work presents a promising graphene-based framework for single-point protein sequencing, enabling detailed amino acid characterization. By optimizing protocols and developing platforms for consistent GFET measurements, we controlled molecular coverage for electrochemical profiling. The building blocks for this technology have been optimized for our platforms and can offer an alternative to traditional methods, with applications in proteomics, biomarker discovery, and diagnostics. Furthermore, our platforms and chemistry offer versatility to probe chemical affinity to peptides.

Phenolic antioxidants are one of the most studied groups of bioactive compounds in life sciences. Their electrooxidation capability has been successfully used in the development of voltammetric sensors for real sample analysis. Nevertheless, the selectivity of the sensor response to target antioxidants is usually insufficient and is a key limiting factor for the practical application of the developed sensors. In the current work, highly selective voltammetric sensors for natural phenolic antioxidants have been developed using glassy carbon electrodes and a layer-by-layer combination of carbon nanotubes and poly(triphenylmethane dyes) containing phenolic fragments in their structure. Carboxylated multi-walled and polyaminobenzene sulfonic acid-functionalized single-walled carbon nanotubes have been used as a substrate for the electrodeposition of polymeric coverages obtained by potentiodynamic electrolysis from triphenylmethane dyes (pyrogallol red, aluminon, phenol red, thymolphthalein). The optimal conditions of electropolymerization have been found on the basis of the voltammetric response of target phenolic antioxidants, i.e., eugenol, flavonoids (hesperidin and naringin, quercetin and rutin), and hydroxycinnamic acids (caffeic, ferulic, and p-coumaric acids). Electropolymerization proceeds via phenoxyl radical formation and its further dimerization and polymerization. A non-conductive polymeric layer in combination with conductive carbon nanotubes provides an improvement in the voltammetric response of target phenolic antioxidants as well as the possibility of their simultaneous detection. Sensors have shown significant increase in the electroactive surface and electron transfer rate compared to bare glassy carbon electrodes. Under conditions of differential pulse voltammetry, the sensors exhibit a sensitive response to phenolic antioxidants within the range from n×10^-8 to n×10^-5 M with the detection limits of 0.0047-730 μM. The sensor's high selectivity response to the target analyte in the presence of structurally related antioxidants is its main advantage over other electrochemical methods. The sensors have been successfully tested on real samples (essential oils, plant materials, and food).

Delayed fluorescence silica-embedded carbon dots (DF@N-CDs/SiO₂) represent an innovative and highly effective platform for nucleic acid detection. These dots exhibit remarkable fluorescence characteristics that enable rapid and sensitive diagnostics. An example of their application is in the detection of the hepatitis C virus (HCV), which can cause asymptomatic chronic infections with serious clinical consequences. The timely and sensitive detection of HCV RNA is crucial for infection control and monitoring treatment response. While current technologies, such as PCR and isothermal amplification-based strategies, are specific, they are often expensive, labor-intensive, and time-consuming, which limits their use in field settings and smaller laboratories.

This study introduces a novel technology that utilizes the Crosslinked Enhanced Emission (CEE) phenomenon. In this context, fluorescent amino-functionalized silica-coated nitrogen-doped carbon dots (N-CDs/SiO₂/NH₂) exhibit substantial fluorescence enhancement upon interaction with unamplified Hepatitis C Virus (HCV) RNA extracted magnetically from clinical samples. This method has been effectively integrated into a 3D-printed microfluidic chip and a standard 96-well plate format, achieving detection limits of 500 IU/mL and 1000 IU/mL, respectively. The chip-based assay provides results in less than 20 minutes, significantly decreasing the processing time in comparison to traditional amplification-based techniques. Analyzing 141 patient samples yielded high sensitivity (96.47%) and specificity (98.79%), underscoring the platform’s efficacy in clinical diagnostics.

This investigation marks the initial application of N-CDs/SiO2 as fluorescent probes for nucleic acid detection, providing a versatile and cost-effective solution that can be readily integrated into existing laboratory environments. Furthermore, it enhances both the speed and accuracy of HCV RNA detection.