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Poly(pyrrole)-nanowires (PPy-NWs) were efficiently printed by using nano printing on flexible thermoplastics, and then used to device an impedimetric immunosensor. The present pioneering technology allow to create high sensitive and disponsable immunosensor devised using a low cost and simple fabrication. The innovative nanocontact printing uses a PDMS stamp replicated from a CD mold. The PPyNW printing uses controlled chemical polymerization to print PPy-NWs on poly (ethylene terephthalate) and polyether ether ketone surfaces. Atomic force microscopy analysis of PPyNW revealed a width, height and a separation length of 125 ± 8 nm, 377 ± 5 nm and 172 ± 4 nm, respectively. The PPy-NWs were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The XPS results evidenced the covalent bonding between the thermoplastic surface and the PPyNWs. As a final point, the immunosensor was tested for the quantification of Interleukin 6 recombinant human (IL6, Ag) using EIS. The PPy-NWs were functionalized via diazonium coupling reaction and carbodiimide crosslinker chemistry for the immobilization of Anti-human IL-6 monoclonal antibodies (IL6 mAb’s). The developed immunosensor exhibited a sensitivity of 0.013 (pg/mL) −1 (linear fitting at R 2 = 0.99) and limit of detection (LOD) of 0.36 pg/mL in a linear range of 1–50 pg/mL for Ag IL-6, with a relative standard deviation percentage (RSD%) at 7.6%. [ABSTRACT FROM AUTHOR]

Smart artificial nano-actuators were developed using electroactive acrylamide polymer nanoparticles by molecular imprinting. These nanoparticles are receptors that mimic the specificity of antibodies and replace enzymes in traditional biosensors allowing highly sensitive and selective monitoring. Electroactive polymer nanoparticles can be synthesized by the including of ferrocene, which confers signaling functions. These actuators operate by a swelling mechanism in response to a specific electrochemical stimulus. Molecular recognition is based on molecular imprinting and binding of the target molecule. The polymer nanoparticles were computationally designed to bind to Metformin and synthesized by controlled free-radical polymerization. Polymer nanoparticles were incorporated on the surface using screen-printed electrodes. As a result, these nano-actuators allow extremely sensitive monitoring of Metformin in human plasma. Metformin is essential for treating various chronic diseases, and monitoring is necessary to reduce collateral drug side effects. Herein, sensing of Metformin was achieved by differential pulse voltammetry (DPV) in a concentration range between 100 and 2000 pM, with a limit of detection of 9 pM and sensitivity at 31.5 nA pM−1 (0.998) in plasma. No cross-reactivity was observed against potential interferences (Sitagliptin and Paracetamol). This technology can be potentially applied for rapid point-of-care testing as an alternative to laboratory-based techniques, reducing the time and cost of the analysis. • Metformin imprinted nanoparticles were computationally designed. • Electroactive nanoparticles were used for Metformin sensing on human plasma. • The sensors are highly sensitive and could be adopted for point-of-care testing. [ABSTRACT FROM AUTHOR]

Smart artificial nano-actuators were developed using electroactive acrylamide polymer nanoparticles by molecular imprinting. These nanoparticles are receptors that mimic the specificity of antibodies and replace enzymes in traditional biosensors allowing highly sensitive and selective monitoring. Electroactive polymer nanoparticles can be synthesized by the including of ferrocene, which confers signaling functions. These actuators operate by a swelling mechanism in response to a specific electrochemical stimulus. Molecular recognition is based on molecular imprinting and binding of the target molecule. The polymer nanoparticles were computationally designed to bind to Metformin and synthesized by controlled free-radical polymerization. Polymer nanoparticles were incorporated on the surface using screen-printed electrodes. As a result, these nano-actuators allow extremely sensitive monitoring of Metformin in human plasma. Metformin is essential for treating various chronic diseases, and monitoring is necessary to reduce collateral drug side effects. Herein, sensing of Metformin was achieved by differential pulse voltammetry (DPV) in a concentration range between 100 and 2000 pM, with a limit of detection of 9 pM and sensitivity at 31.5 nA pM−1 (0.998) in plasma. No cross-reactivity was observed against potential interferences (Sitagliptin and Paracetamol). This technology can be potentially applied for rapid point-of-care testing as an alternative to laboratory-based techniques, reducing the time and cost of the analysis. • Metformin imprinted nanoparticles were computationally designed. • Electroactive nanoparticles were used for Metformin sensing on human plasma. • The sensors are highly sensitive and could be adopted for point-of-care testing. [ABSTRACT FROM AUTHOR]

We present a new low-cost technology to fabricate poly(pyrrole) microwires (PPy-μWs) by micro contact printing (μCP) and controlled chemical polymerization (μCP-CCP) using three different techniques (“ grafting printing ”, “ addressed printing ”, and “ direct printing ”. These developed techniques provide a platform to regulate PPy wire size and shape using N-(3-trimethoxysilyl-propyl) pyrrole (Py-silane) for the “ addressed printing ” and “ direct printing ” techniques, respectively. The technique uses a silicon mold to produce micropatterned polydimethylsiloxane (PDMS) stamps. The micropatterned PDMS stamp was employed to print PPy-μWs with an improvement observed from “ direct printing ” > “ addressed printing ” > “ grafting printing ”. Therefore, for “ direct printing ”, PPy-μWs were printed on: poly(ethylene terephthalate) (PETE), cyclic olefin copolymer (COC), poly(ethylene 2,6-naphthalate (PEN), and polyimide (PI) surfaces. Here, we have studied the printing of wires and the surface morphology to understand the characteristics of PPy patterns by optical microscopy, scanning electrode microscopy (SEM), and atomic force microscopy (AFM). The functionality of the PPy-μW matrix was also analyzed for immune detection. Here, fluorescent imaging was used to certify the detection of recombinant human interleukin-10 (rh IL-10). PPy-μWs were functionalized using gluteraldehyde (GA) for the specific immobilization of anti-human interleukin-10 monoclonal antibodies (anti-IL-10 mAb's). The immunosensor present a sensitivity of 0.026 (pg/mL −1 ) to the respective rh IL-10 in a linear range of 1–50 pg/mL and a limit of detection at 0.36 pg/L. Finally the PPy-μW matrix was successfully tested for cytokine bioassays using electrochemical impedance spectroscopy (EIS) and presents outstanding properties as a matrix for biosensing. [ABSTRACT FROM AUTHOR]

• Molecularly imprinted polymer nanoparticles tagged with a redox probe combine both recognition and reporting functions. • No enzymatic reactions or electroxidation of analyte is needed. • Applicability in real scenarios, fast response, high selectivity, no saturation in the clinical relevant range in human plasma. • Direct detection method avoiding cross reactivity or false positives. • This technology is robust and can be potentially applied for monitoring paracetamol plasma levels and to diagnose paracetamol poisoning. A highly sensitive disposable electrochemical sensor for paracetamol was devised using electroactive molecularly imprinted polymers nanoparticles (nanoMIPs). NanoMIPs were prepared by solid-phase synthesis. Polymer composition included itaconic acid as a specific functional monomer and ferrocene as redox label, which confers electroactivity to the nanoparticles. NanoMIPs were characterised by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and scanning electron microscopy (SEM). Sensors were fabricated by covalent attachment of nanoMIPs on screen-printed carbon electrodes and then employed for electrochemical determination of paracetamol using differential pulse voltammetry (DPV). The sensor was successfully evaluated in spiked human plasma with recoveries at 94–108 % and presenting a sensitivity of 6.18 ± 0.22 μA mM−1. The limit of detection and limit of quantification for the sensor were found to be 50 μM and 167 μM, respectively, in a linear concentration range between 0.1 and 1 mM. High selectivity was demonstrated, with no interference found in the presence of caffeine, procainamide or ethyl 4-aminobenzoate. The sensors exhibited high reproducibility (RSD, 4.8 %), fast response time (∼8 s) and acceptable shelf life (90 days), confirming its suitability for point of care diagnostic applications. [ABSTRACT FROM AUTHOR]

• An electrochemical sensor was devised and fabricated for fumonisin B 1 (FB 1) determination. • NanoMIPs particles were used to produce an FB 1 recognising unit of the chemosensor. • The DPV and EIS were applied for transducing the FB 1 recognition signals. • The chemosensor was highly sensitive and selective to FB 1. Fumonisin B 1 (FB 1) is a carcinogenic mycotoxin contaminating food and animal feed. Although the sensitivity of chromatography and immunoassays is high for FB 1 determination, these techniques are laborious, costly, and challenging in making them portable. Herein, a highly sensitive and selective electrochemical sensor using molecularly imprinted polymer nanoparticles (nanoMIPs) for FB 1 recognition was devised and fabricated. NanoMIPs were prepared by free-radical polymerisation using the solid-phase synthesis and characterised by DLS, SPR, SEM, AFM, and FTIR spectroscopy. The chemosensor fabrication was prepared in two steps. First, a film of the conducting polypyrrole-(zinc porphyrin) composite was deposited on a Pt electrode by electropolymerisation. Then, nanoMIPs were covalently attached to this film. Both electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) served for analytical signal transduction. The respective chemosensor sensitivity was 0.442 kΩ/pM (R 2 = 0.98) and 0.281 μA/pM (R 2 = 0.96) in the concentration range of 1 fM to 10 pM FB 1. The limit of detection was impressively low, equalling to 0.03 and 0.7 fM, respectively, while the DPV determined imprinting factor was appreciably high 6.28. This electrochemical sensor revealed no cross-reactivity to other mycotoxins. The FB 1 recovery in the FB1 spiked maize was high (96–102 %). Thus, the chemosensor proved useful as an effective alternative tool for FB 1 determination in maize. [ABSTRACT FROM AUTHOR]

Cadmium is a highly toxic heavy metal, even at low concentrations. Moreover, it bio-accumulates with a long biological half-life producing a wide variety of acute and chronic effects like cancer in humans. Therefore, there is significant interest in providing a portable and user-friendly sensor for heavy metal detection. A highly sensitive and selective electrochemical sensor for Cd(II) determination was developed as an alternative. The Cd (II) receptors were integrated into the sensor using an ion-imprinted polymer film (IIPs film). Accordingly, 4-aminophenylacetic acid (4-APA) was electropolymerised in the presence of Cd(II) ions as a template using cyclic voltammetry (CV) on screen-printed carbon electrodes (SPCEs). Imprinted cavities were obtained after the alkaline elution of ions. Sensor characterisation was performed using SEM, ATR-FTIR and electrochemical methods, such as cyclic voltammetry (CV) and electrochemical Impedance Spectroscopy (EIS), and compared to control experiments (not imprinted polymeric film, NIP film). Analytical performances of the IIP sensor revealed a sensitivity 5-order of magnitude higher than the NIP response in a concentration range from 10 to 1200 nM of Cd (II). This technology can potentially be applied for water quality control and monitoring of heavy metals. [Display omitted] • Electropolymerised 4-aminophenylacetic acid imprinted films have been prepared. • A Cd(II) sensor based on imprinted films has been developed. • Electroactivity of developed films overcomes the need for redox labels for sensing. • An imprinted factor of 5 was obtained. • Disposable Cd(II)-IIP films sensors can be applied to on-field monitoring purposes. [ABSTRACT FROM AUTHOR]

An original biosensor was developed for the direct conductometric detection of ochratoxin A (OTA) in olive oil samples. The biosensor is based on thermolysin (TLN) immobilization into a polyvinyl alcohol (PVA)/polyethylenimine (PEI) matrix containing gold nanoparticles (AuNPs) and cross-linked at the surface of gold interdigitated microelectrodes using glutaraldehyde. Under optimal conditions (35 min cross-linking time, working pH of 7 and temperature of 25 °C), the biosensor response was linear up to 60 nM OTA, with a sensitivity of 597 μS μM −1 and a limit of detection of 1 nM. This value was 700 times lower than the detection limit obtained using the more classical method based on enzyme cross-linking in the presence of bovine serum albumin (BSA). PVA/PEI hydrogel creates a very favorable aqueous environment for the enzyme. In addition, interactions between protonated amino groups of PEI and negative charges of both citrated AuNPs and thermolysin improve their dispersion in the polymer blend, favoring enzyme stabilization and accessibility of the substrate. No conductometric signal was observed after OTA injection in the absence of AuNPs, in agreement with the insulating properties of the cross-linked PVA/PEI hydrogel film. Incorporation of AuNPs into the TLN/BSA biomembrane helped improving the sensitivity by 5.3 but this latter remained 140 times lower than the sensitivity of TLN/AuNPs/(PVA/PEI) biosensor. The study of enzyme kinetics showed that V i vs [OTA] plot exhibited a non-hyperbolic trend, indicating that kinetics does not display a Michaelis–Menten behavior. Biosensor response times are longer (7–48 min) comparatively to TLN/BSA biosensor with a maximal value of 25 min. This difference is due to the diffusion phenomenon through the pores of the polymer membrane. The proposed OTA biosensor was very reproducible with a relative standard deviations (RSDs) in the 3–15% range and stable over a 30-days period when stored at 4 °C in 20 mM phosphate buffer between two measurements. The method was further evaluated using commercial doped olive oil samples. No pretreatment of the sample was needed for testing and no matrix effect was observed. Recovery values were close to 100% demonstrating the suitability of the proposed method for OTA screening in olive oil. [ABSTRACT FROM AUTHOR]