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Cells mechanically interact with their environment to sense, for example, topography, elasticity and mechanical cues from other cells. Mechano-sensing has profound effects on cellular behaviour, including motility. The current study aims to develop a mathematical model of cellular mechano-sensing on planar elastic substrates and demonstrate the model’s predictive capabilities for the motility of individual cells in a colony.In the model, a cell is assumed to transmit an adhesion force, derived from a dynamic focal adhesion integrin density, that locally deforms a substrate, and to sense substrate deformation originating from neighbouring cells. The substrate deformation from multiple cells is expressed as total strain energy density with a spatially varying gradient. The magnitude and direction of the gradient at the cell location define the cell motion. Cell-substrate friction, partial motion randomness, and cell death and division are included.The substrate deformation by a single cell and the motility of two cells are presented for several substrate elasticities and thicknesses. The collective motility of 25 cells on a uniform substrate mimicking the closure of a circular wound of 200 μm is predicted for deterministic and random motion. Cell motility on substrates with varying elasticity and thickness is explored for four cells and 15 cells, the latter again mimicking wound closure. Wound closure by 45 cells is used to demonstrate the simulation of cell death and division during migration.The mathematical model can adequately simulate the mechanically-induced collective cell motility on planar elastic substrates. The model is suitable for extension to other cell and substrates shapes and the inclusion of chemotactic cues, offering the potential to complementin vitroandin vivostudies.

This work demonstrates a facile electropolymerization of a dl-methionine (dl-met) conducting polymeric film on a gold nanoparticle (AuNPs)-modified glassy carbon electrode (GCE). The resulting sensor was successfully applied for the sensitive detection of paroxetine·HCl (PRX), a selective serotonin (5-HT) reuptake inhibitor (SSRIs), in its pharmaceutical formulations. The sensor was characterized morphologically using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) and electrochemical techniques such as differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The proposed sensor, poly (dl-met)/AuNPs-GCE, exhibited a linear response range from 5 × 10−11 to 5 × 10−8 M and from 5 × 10−8 to 1 × 10−4 M using DPV with lowest limit of detection (LOD = 1 × 10−11 M) based on (S/N = 3). The poly (dl-met)/AuNPs-GCE sensor was successfully applied for PRX determination in three different pharmaceutical formulations with percent recoveries between 96.29% and 103.40% ± SD (±0.02 and ±0.58, respectively).

Design of experiment approach has recently become an urgent requirement for different experimental measurements. Not only due to the increased expenses for purchasing chemicals and equipment but also, to reduce time required to conduct several one-variable at a time experiments to optimize the operating conditions of an experimental design. Design of experiments has excellent applicability in analytical process related to method development based on multiple variants used for pharmaceutical, food and environmental analysis. Application of experimental design has become effective to identify and optimize the significant factors, and to achieve adequate results using few experimental trials. Electrochemical sensors represent a class of fast, reliable and economic tools in analytical chemistry, with vast applicability to different fields. This review aims at presenting the most recently used screening and optimization designs during (2019-2021) for the fabrication and operation variables of electrochemical sensors and how can they be efficiently correlated.

Vardenafil (VRL) is one of the highly potent PDE-5 inhibitor pharmaceutical compounds used for treatment of erectile dysfunction. In this work, the sensor was fabricated via electropolymerization of pyrrole (Py) as a functional monomer in presence of VRL on a platinum electrode (PtE) modified with electrodeposited platinum nanoparticles (PtNPs) followed by electrochemical overoxidation to yield overoxidized polypyrrole (OPPy). During the sensor’s fabrication, seven factors need to be optimized including, pyrrole concentration (PyConc.) (mM), VRL concentration (VRLconc.) (mM), no of polymerization cycles (no. of cycles), incubation time (t.rebind) (min), pH of the incubation (pH), accumulation time (t.acc) (s) and accumulation potential (Pot.acc) (V). That is why fractional factorial design was first applied for screening the most significant factors followed by central composite design (CCD) optimization in order to have a correlative overview of the different interactions between these variables at the same time, unlike the traditional approach involving changing one factor at a time. Stepwise construction of the sensor was characterized electrochemically using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) and topographically using Scanning electron microscopy (SEM). The sensor showed linearity over the range of concentrations (1 × 10-12 M – 5 × 10-8 M) using differential pulse voltammetry (DPV) and EIS with a significantly low limit of detections 2 × 10-13 M and 0.9 × 10-13 M (S/N = 3), respectively under optimum conditions. The fabricated (OPPy/PtNPs/PtE) sensor was successfully applied to determine VRL in two pharmaceutical formulations, spiked urine and serum samples with percent recoveries between (98.9 % and 102.2 %) ± SD (±0.02 and ± 0.48).