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Fumonisins (FBs) can be found extensively in feedstuffs, foodstuffs, and crops. The consumption of the fumonisin-contaminated corn can result in esophageal cancer. In addition, the secondary metabolites of fungi termed mycotoxins may have some adverse effects on animals and humans such as estrogenicity, immunotoxicity, teratogenicity, mutagenicity, and carcinogenicity. Hence, developing sensitivity techniques for mycotoxins determination is of great importance. This paper reports the latest developments of nanomaterial-based electrochemical biosensing, apta-sensing, sensing, and immunosensing analyses to detect fumonisins. A concise study of the occurrence, legislations, toxicity, and distribution of FBs in levels monitoring was done. The techniques, different detection matrices, and approaches to highly selective and sensitive sensing methods were reviewed. The review also summarizes the salient features and the necessity of biosensing assessments in FBs detection, and diverse immobilization techniques. Furthermore, this review defined the performance of various electrochemical sensors using different detection elements couples with nanomaterials fabricated applying different detection elements coupled with nanomaterials (metal oxide nanoparticles (NPs), metal NPs, CNT, and graphene), the factors limiting progress, and the upcoming tasks in successful aptasensor fabrication with the functionalized nanomaterials.

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Gold nanostars (AuNSs) demonstrate an intense electromagnetic field around tip of branches. In this research, we employed AuNSs-enhanced electrochemiluminescence (ECL) emission from graphitic carbon nitride nanosheets (g-CN nanosheets) to detect CD133 peptide as a cancer stem cell membrane biomarker. In this biosensor, the g-CN nanosheets were decorated with AuNSs (AuNSs@g-CN nanosheets). AuNSs@g-CN nanosheets exhibited strong and stable cathodic ECL emission compared to that of pure g-CN nanosheets. The ECL intensity from the AuNSs@g-CN nanosheets was over 30% higher than that of spherical gold nanoparticles (spherical AuNPs) decorated g-CN nanosheets. The additional ECL enhancement of AuNSs was due to the localized surface plasmon resonance (LSPR) effect located around multiple branch tips of AuNSs. The RSD of ECL curves intensities, obtained from successive potential scans for 10 cycles, were less than 4%, indicating the superior stability of the AuNSs@g-CN nanosheets. Under optimum conditions, the ECL intensity of GCE/AuNSs@g-CN nanosheets/anti-CD133 decreased linearly with CD133 peptide concentration in the range of 0.05-100 ng mL-1. The LOD achieved was 0.257 ng mL-1 (S/N = 3). The applicability of the designed biosensor in real samples was examined through the determination of CD133 peptide in spiked serum samples, from which satisfactory results were obtained.

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In this research, efficient and novel catalysts based on hierarchical carbon nanohorns-titanium nanoflowers have been prepared by one-pot solvothermal process. Hydrogen generation from dye-contaminated water and dye degradation along with electrochemical supercapacitance performance have been investigated using the synthesized hierarchical catalyst to produce 4500 µmol g-1 h-1 of hydrogen from the photocatalytically generated aqueous methylene blue and methyl orange dyes, which were degraded up to 90% under natural solar light irradiation. These results offer a new path to generate hydrogen from the aqueous dyes. The catalysts electrode showed 164.6 F g-1 supercapacitance at 5 mV s-1 scan rate, which is nearly 1.3 and 1.65-times higher than that of pristine titanium nanoflower and carbon nanohorns electrodes, respectively. Such superior results were achieved due to good crystallinity, improved optical absorption strength, strong chemical composition between the two components, and hierarchical morphology as demonstrated from XRD, UV-DRS, TEM, XPS, and Raman spectral characterizations.

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A completely new droplet breakup phenomenon is reported for droplets passing through a constriction in an electrokinetic flow. The breakup occurs during the droplet shape recovery process past the constriction throat by the interplay of the dielectrophoretic stress release and the interface energy for droplets with smaller permittivity than that of the ambient fluid. There are conditions for constriction ratios and droplet size that the droplet breakup occurs. The numerical predictions provided here require experimental verification, and then can give rise to a novel microfluidic device design with novel droplet manipulations.

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Developing a novel peroxidase nano-mimetic is a challenging research topic in biosensing field. Herein, WS2 nanosheets (WS2 NS) decorated with silver nanoclusters (AgNCs) was introduced as a new nanocomposite with improved peroxidase mimetic behavior. WS2 NS/AgNCs nanocomposite was synthesized by simple chemical reduction of silver cations in the presence of WS2 NS. The enhanced catalytic activity of nanocomposite in chemical and electrochemical reduction of H2O2 was studied using colorimetry, fluorometry and electrochemical techniques. Attaching the AgNCs on the surface of WS2 NS effectively improved the catalytic activity of these nanosheets, which may be connected to the difference of the Fermi energy levels of coupled nanomaterial. The unequal Fermi levels cause charge separation between two phases creating highly active sites on the interface of coupled nanomaterial. Moreover, the new mimetic nanocomposite was applied for the analysis of glucose in blood, based on its enzymatic oxidation using glucose oxidase and then, on the measurement of produced H2O2 by sensitive fluorescence detection system. In optimum condition, a linear association was found between the generated fluorescence intensity and glucose logarithmic concentration in the range of 0.05-400 µM, and the limit of detection (3S/m) was 21 nM.

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The translational motion of small particles in an electrokinetic fluid flow through a constriction can be enhanced by an increase of the applied electric potential. Beyond a critical potential, however, the negative dielectrophoresis (DEP) can overpower other forces to prevent particles that are even smaller than the constriction from passing through the constriction. This DEP choking phenomenon was studied previously for rigid particles. Here, the DEP choking phenomenon is revisited for deformable particles, which are ubiquitous in many biomedical applications. Particle deformability is measured by the particle shear modulus, and the choking conditions are reported through a parametric study that includes the channel geometry, external electric potential, and particle zeta potential. The study was carried out using a numerical model based on an arbitrary Lagrangian-Eulerican (ALE) finite-element method.

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Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymer-free Newtonian fluid. This stream-wise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a consequence of the competition between electrokinetic force and viscoelastic force induced in the constriction. The electric field magnitude, particle size, and PEO concentration are all found to positively affect this viscoelasticity-related particle oscillation due to their respective influences on the two forces.

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Shape is an intrinsic marker of cell cycle, an important factor for identifying a bioparticle, and also a useful indicator of cell state for disease diagnostics. Therefore, shape can be a specific marker in label-free particle and cell separation for various chemical and biological applications. We demonstrate in this work a continuous-flow electrical sorting of spherical and peanut-shaped particles of similar volumes in an asymmetric double-spiral microchannel. It exploits curvature-induced dielectrophoresis to focus particles to a tight stream in the first spiral without any sheath flow and subsequently displace them to shape-dependent flow paths in the second spiral without any external force. We also develop a numerical model to simulate and understand this shape-based particle sorting in spiral microchannels. The predicted particle trajectories agree qualitatively with the experimental observation.