Search Results (5)

Infectious diseases, such as COVID-19, continue to cause an enormous burden of death and disability in developing countries, and there is an urgent need to better understand these infectious pathogens and develop ways to control their spread. We have developed a new type of testing strategy based on electrochemical biosensing aspects, created using a microfluidic detection platform for rapid, sensitive, and specific detection of infectious SARS-CoV-2 and its variants. The target compounds, i.e., SARS-CoV-2 variants, were selected due to the current worldwide outbreak; however, the fabricated biosensing aspect may be expanded to future emerging pathogens by undemanding modifications. The biosensor platform is based on screen-printed electrodes (SPEs), modified with nanostructured polystyrene (PS)/polyaniline (PANI)-Au NP composites. The surface of modified-SPEs is later immobilized using different representative receptor elements, i.e., specific viral antibodies. Tackling PS/PANI-Au NP composites on the nanoscale enables us to exploit its outstanding conductivity, biocompatibility, and high surface area which facilitate the loading of a huge amount of viral receptor elements (Ab), thus resulting in high sensitivity, specificity, and low detection limits (i.e., at attomolar concentration levels). Such a construction is able to translate this specific covalent interaction (Ab) with its corresponding binding viral target, i.e., receptor-binding domain ((RBD) of spike (S) glycoprotein) into a measurable, concentration-dependent electrochemical response. By creating an electrochemical readout, data enable qualitative and quantitative analysis. The fabricated system represents a low-cost and efficient alternative to conventional assays for testing as it offers a simple in-situ method of analysis in much shorter time frames. Its feasible design is easy to use and can be operated by patients themselves using simple samples such as saliva, thus allowing population-scale screening. Full article

Skin pH can be used for monitoring infections in a healing wound, the onset of dermatitis, and hydration in sports medicine, but many challenges exist in integrating conventional sensing materials into wearable platforms. We present the development of a flexible, textile-based, screen-printed electrode system for biosensing applications, and demonstrate flexible polyaniline (PANI) composite-based potentiometric sensors on a textile substrate for real-time pH measurement. The pH response of the optimized PANI/dodecylbenzene sulfonic acid/screen-printing ink composite is compared to electropolymerized and drop-cast PANI sensors via open circuit potential measurements. High sensitivity was observed for all sensors between pH 3–10, with a composite based on PANI emeraldine base, demonstrating sufficient response time and a linear sensitivity of −27.9 mV/pH. This exceeded prior flexible screen-printed pH sensors in which all parts of the sensor, including the pH sensing material, are screen-printed. Even better sensitivity was observed for a PANI emeraldine salt composite (−42.6 mV/pH), although the response was less linear. Furthermore, the sensor was integrated into a screen-printed microfluidic channel demonstrating sample isolation during measurement for wearable, micro cloth-based analytical devices. This is the first fully screen-printed flexible PANI composite pH sensor demonstrated on a textile substrate that can additionally be integrated with textile-based microfluidic channels. Full article

A new era of composite organic materials, nanomaterials, and printed electronics is emerging to the applications of thermoelectric generators (TEGs). Special attention is focused on carbon nanomaterials and conducting polymers, and the possibility to form pastes and inks for various low-cost deposition techniques. In this work, we present a novel approach to the processing of composite materials for screen-printing based on carbon nanotubes (CNTs) and polyaniline (PANI), supported with a dielectric polymer vehicle. Three different types of such tailor-made materials were prepared, with a functional phase consisted of carbon nanotubes and polyaniline composites fabricated with two methods: dry mixing of PANI CNT powders and in situ polymerisation of PANI with CNT. These materials were printed on flexible polymer substrates, exhibiting outstanding mechanical properties. The best parameters obtained for elaborated materials were $\sigma =405.45 \mathrm{S}·{\mathrm{m}}^{-1}$, $S=15.4 \mathsf{\mu }\mathrm{V}·{\mathrm{K}}^{-1}$, and $PF=85.2 \mathrm{nW}·{\mathrm{m}}^{-1}{\mathrm{K}}^{-2}$, respectively. Full article

Polyaniline (PANI) is a conducting polymer, widely used in gas-sensing applications. Due to its classification as a semiconductor, PANI is also used to detect reducing ammonia gas (NH₃), which is a well-known and studied topic. However, easier, cheaper and more straightforward procedures for sensor fabrication are still the subject of much research. In the presented work, we describe a novel, more controllable, synthesis approach to creating NH₃ PANI-based receptor elements. The PANI was electrochemically deposited via cyclic voltammetry (CV) on screen-printed electrodes (SPEs). The morphology, composition and surface of the deposited PANI layer on the Au electrode were characterised with electron microscopy, Fourier-transform infrared spectroscopy and profilometry. Prior to the gas-chamber measurement, the SPE was suitably modified by Au sputtering the individual connections between the three-electrode system, thus showing a feasible way of converting a conventional three-electrode electrochemical SPE system into a two-electrode NH₃-gas detecting system. The feasibility of the gas measurements’ characterisation was improved using the gas analyser. The gas-sensing ability of the PANI-Au-SPE was studied in the range 32–1100 ppb of NH₃, and the sensor performed well in terms of repeatability, reproducibility and sensitivity. Full article

In this work, we propose an electrochemical DNA aptasensor for the detection of profenofos, an organophosphorus pesticide, based on a competitive format and disposable graphite screen-printed electrodes (GSPEs). A thiol-tethered DNA capture probe, which results to be complementary to the chosen aptamer sequence, was immobilised on gold nanoparticles/polyaniline composite film-modified electrodes (AuNPs/PANI/GSPE). Different profenofos solutions containing a fixed amount of the biotinylated DNA aptamer were dropped onto the realized aptasensors. The hybridisation reaction was measured using a streptavidin-alkaline phosphatase enzyme conjugate, which catalyses the hydrolysis of 1-naphthyl -phosphate. The 1-naphtol enzymatic product was detected by means of differential pulse voltammetry (DPV). The aptasensor showed itself to work as a signal off sensor, according to the competitive format used. A dose response curve was obtained between 0.10 μM and 10 μM with a detection limit of 0.27 μM. Full article