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Electrospinning has emerged as a very powerful method combining efficiency, versatility and low cost to elaborate scalable ordered and complex nanofibrous assemblies from a rich variety of polymers. Electrospun nanofibers have demonstrated high potential for a wide spectrum of applications, including drug delivery, tissue engineering, energy conversion and storage, or physical and chemical sensors. The number of works related to biosensing devices integrating electrospun nanofibers has also increased substantially over the last decade. This review provides an overview of the current research activities and new trends in the field. Retaining the bioreceptor functionality is one of the main challenges associated with the production of nanofiber-based biosensing interfaces. The bioreceptors can be immobilized using various strategies, depending on the physical and chemical characteristics of both bioreceptors and nanofiber scaffolds, and on their interfacial interactions. The production of nanobiocomposites constituted by carbon, metal oxide or polymer electrospun nanofibers integrating bioreceptors and conductive nanomaterials (e.g., carbon nanotubes, metal nanoparticles) has been one of the major trends in the last few years. The use of electrospun nanofibers in ELISA-type bioassays, lab-on-a-chip and paper-based point-of-care devices is also highly promising. After a short and general description of electrospinning process, the different strategies to produce electrospun nanofiber biosensing interfaces are discussed.

In this study, we developed a highly sensitive aptasensor based on polyaniline electro-polymerization, new nanomembrane composite, and aptamer (PANI-MWCNT@Chs-APT) for the electrochemical detection of estradiol valerate in real samples. The high sensitivity and selectivity of the aptasensor were demonstrated by evaluating its response to some potential interference having structural similarities. The selectivity of this aptasensor showed high selectivity for estradiol valerate among other interfering hormones. Electrochemical impedance spectroscopy combined with the standard added method used to characterize the modified gold electrodes as well as for the detection of estradiol valerate both in pharmaceutical and in women’s blood. It showed that the response of the aptasensor rose with increasing estradiol valerate concentration, which highlighted the good sensitivity of the aptasensor to estradiol valerate with a very low limit of detection of 0.56 fM. This was very promising for rapid analysis of estradiol valerate detection in pharmaceutical and biological samples. Graphic abstract

A sensitive electrochemical molecularly-imprinted sensor was developed for the detection of aflatoxin B1 (AFB1), by electropolymerization of p-aminothiophenol-functionalized gold nanoparticles in the presence of AFB1 as a template molecule. The extraction of the template leads to the formation of cavities that are able to specifically recognize and bind AFB1 through π-π interactions between AFB1 molecules and aniline moities. The performance of the developed sensor for the detection of AFB1 was investigated by linear sweep voltammetry using a hexacyanoferrate/hexacyanoferrite solution as a redox probe, the electron transfer rate increasing when the concentration of AFB1 increases, due to a p-doping effect. The molecularly-imprinted sensor exhibits a broad linear range, between 3.2 fM and 3.2 µM, and a quantification limit of 3 fM. Compared to the non-imprinted sensor, the imprinting factor was found to be 10. Selectivity studies were also performed towards the binding of other aflatoxins and ochratoxin A, proving good selectivity.

The detection of pathogenic bacteria remains a challenge for the struggle against biological weapons, nosocomial diseases, and for food safety. In this research, our aim was to develop an easy-to-use electrochemical immunosensor for the detection of pathogenic Staphylococcus aureus ATCC25923. The biosensor was elaborated by the immobilization of anti-S. aureus antibodies using a self-assembled monolayer (SAMs) of 3-Mercaptopropionic acid (MPA). These molecular assemblies were spontaneously formed by the immersion of the substrate in an organic solvent containing the SAMs that can covalently bond to the gold surface. The functionalization of the immunosensor was characterized using two electrochemical techniques: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Here, the analysis was performed in phosphate buffer with ferro/ferricyanide as the redox probe. The EIS technique was used for affinity assays: antibody-cell binding. A linear relationship between the increment in the electron transfer resistance (RCT) and the logarithmic value of S. aureus concentration was observed between 10 and 106 CFU/mL. The limit of detection (LOD) was observed at 10 CFU/mL, and the reproducibility was calculated to 8%. Finally, a good selectivity versus E. coli and S. epidermidis was obtained for our developed immunosensor demonstrating its specificity towards only S. aureus.

Early, inexpensive, reliable, and accurate diagnosis of cardiovascular abnormalities has become of crucial importance to prevent and halt their progression. Herein, we report a label‐free electrochemical magnetoimmunosensing for monitoring cardiac diseases through qualitative and quantitative detection of cardiac troponin‐T (Tpn‐T) in aqueous solution. In this context, a nanocomposite of gold nanoparticles coated a magnetic nanoscale zero‐valent iron core (NZVI©Au) is employed as a substrate to facilitate the electron transfer and to bind more primary Tpn‐T antibodies. The immunosensing platform consists of an anti‐cardiac troponin‐T antibody (Tpn‐T‐ab) modified NZVI©Au magnetic membrane attached onto a boron doped diamond (BDD) electrode. Sensing experiments were performed by the imposition of an external magnetic field at the backside of the electrode. The sensor response was performed using impedimetric assays, wherein the increase in the electron transfer resistance (Rct) correlated with an increase in the concentration of Tpn‐T. Linearity was obtained in the range from 1 to 109 fg/mL with a detection limit of 0.354 fg/mL. The proposed platform exhibited high selectivity, high reproducibility, and good stability, while retaining more than 90% of the sensitivity after 2 weeks of storage at 4°C. The determination of Tpn‐T is well compared with previously reported methods and has been successfully tested in serum samples. This encouraging result suggests that the developed sensing strategy provides a high potential for the early assessment of Tpn‐T in point‐of‐care testing applications. A new concept of label‐free impedimetric magnetoimmunosensor for Tpn‐T detection is described in this work. A nanocomposite of gold nanoparticles (AuNPs) decorating a magnetic NZVI core is synthesized and used as modifier of BDD electrode. The presence of the NZVI©Au core‐shell nanocomposite onto the BDD surface facilitated the covalent linking of primary Tpn‐T antibodies. The targeted Tpn‐T detection was then performed by means of electrochemical impedance measurements, wherein the increase in the electron transfer resistance (Rct) correlated with an increase in the concentration of Tpn‐T.

In this work, an enzymatic sensor, based on a bionanocomposite film consisting of a polyelectrolyte complex (PEC) (Chitosan/kappa-carrageenan) doped with gold nanoparticles (AuNPs) encapsulating glucose oxidase (GOD) deposited on a gold electrode (Au) for glucose sensing, is described. Using the electrocatalytic synergy of AuNPs and GOD as a model of enzyme, the variation of the current (µA) as a function of the log of the glucose concentration (log [glucose]), shows three times higher sensitivity for the modified electrode (283.9) compared to that of the PEC/GOD modified electrode (93.7), with a detection limit of about 5 µM and a linearity range between 10 µM and 7 mM. The response of the PEC/AuNPs/GOD based biosensor also presents good reproducibility, stability, and negligible interfering effects from ascorbic acid, uric acid, urea, and creatinine. The applicability of the PEC/AuNPs/GOD based biosensor was tested in glucose-spiked saliva samples and acceptable recovery rates were obtained.

In this work, we report the adaptation of bacteria to stress conditions that induce instability of their cultural, morphological, and enzymatic characters, on which the identification of pathogenic bacteria is based. These can raise serious issues during the characterization of bacteria. The timely detection of pathogens is also a subject of great importance. For this reason, our objective is oriented towards developing an immunosensing system for rapid detection and quantification of Staphylococcus aureus . Polyclonal anti- S. aureus are immobilized onto modified gold electrode by self-assembled molecular monolayer (SAM) method. The electrochemical performances of the developed immunosensor were evaluated by impedance spectroscopy through the monitoring of the charge transfer resistance at the modified solid/liquid interface using ferri-/ferrocyanide as redox probe. The developed immunosensor was applied to detect stressed and resuscitate bacteria. As a result, a stable and reproducible immunosensor with sensitivity of 15 kΩ/decade and a detection limit of 10 CFU/mL was obtained for the S. aureus concentrations ranging from 10 1 to 10 7  CFU/mL. A low deviation in the immunosensor response (±10 %) was signed when it is exposed to stressed and not stressed bacteria.

A facile synthesis of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridine derivatives is reported which is based on POCl 3 -mediated cyclodehydration followed by double Suzuki–Miyaura cross-coupling. The absorption and fluorescence properties of the obtained products were investigated and their HOMO/LUMO energy levels were estimated by cyclic voltammetry measurements. Besides, density functional theory calculations were carried out for further exploration of their electronic properties.

The aim of this paper is to determine the optimal open loop solution and a nonlinear delay-dependent state feedback suboptimal control for a class of nonlinear polynomial time delay systems. The proposed method uses a hybrid of block pulse functions and Legendre polynomials as an orthogonal base for system’s states and input expansion. Hence, the complex dynamic optimization problem is then reduced, with the help of operational properties of the hybrid basis and Kronecker tensor product lemmas, to a nonlinear programming problem that could be solved with available NLP solvers. A practical nonlinear feedback controller gains are deduced with respect to a least square formalism based on the optimal open loop control results. Simulation results show efficiency of the proposed numerical optimal approach.

Quality control in silicon steel manufacturing process is a crucial step. The application of image processing techniques is very useful in steel inspection and manufacturing. It has established to be the most reliable and promising solution for the development of an automatic defect detection. Since the surface of the silicon steel strip has a cluttered background and defects with small sizes, flaws detection becomes a complex task. In this paper a novel rapid algorithm based on anisotropic diffusion and saliency map is proposed for detection of defects in images of hot rolled silicon steel. The algorithm first adopted a saliency map to enhance defects. Then the computed saliency map was employed in the anisotropic diffusion coefficient function as an orientation guide of the diffusion flow. The aim behind using salient feature is that a small defect can frequently attract attention of human eyes which permits to identify defects in high textured image. Finally, the defects were extracted using a local threshold operator. To verify the validity of the proposed algorithm, extensive experiments were realized on an image database of silicon steel strip then a comparison with traditional diffusion algorithms was given. Experimental results show that this method achieves accuracy and outperforms traditional methods in terms of accuracy and robustness.