Evaluation de l’activité du cadmium, en présence du zinc, sur les structures des tissus régulateurs du métabolisme chez le rat Wistar

Le sulfate de Cadmium (CdSO4) et le chlorure de Zinc (ZnCl2) ont des effets antagonistes. Le Cd est connu pour son effet nécrotique et le Zn pour son rôle protecteur. L’objectif de cette étude est d’évaluer les effets de l’exposition au Cd sur l’histologie du foie et des reins chez des rats Wistar en présence du Zn. L’étude a porté sur 16 rats, âgés de 4 mois, qui ont été subdivisés en 4 groupes de 4 rats, le 1er groupe recevait par voie orale du Cd (0,15 mg/ kg de poids corporel) pendant un mois, le second groupe a été exposé au Zn à la même dose, un 3e groupe recevait un mélange (Cd-Zn) et le 4e groupe était le témoin recevant de l’eau de robinet dans les même conditions. Les résultats ont montré que  l’exposition des rats au Cd a induit une diminution de leur poids corporel. L’examen histologique, chez les rats exposés au Cd, a révélé des désorganisations cellulaires, des atypies cyto-nucléaires et des nécroses au niveau des tissus hépatiques et rénaux. Par ailleurs, les animaux ayant reçu du Zn ou un mélange Cd-Zn ont préservé l’intégrité de l’organisation cellulaire et nucléaire de leur tissu. L’exposition au Cd était responsable de l’apparition d’importants changements morphologique et histologique chez le rat mais la présence du Zn a atténué partiellement les effets toxiques induits par le Cd.Mots clés : Cadmium, zinc, antagonistes, foie, reins, histologie

Improved peroxide biosensor based on Horseradish Peroxidase/Carbon Nanotube on a thiol-modified gold electrode

A new 3-dimensional (3D) network of crosslinked Horseradish Peroxidase/Carbon Nanotube (HRP/CNT) on a thiol-modified Au surface has been described in order to build up the effective electrical wiring of the enzyme units with the electrode. The synthesized 3D HRP/CNT network has been characterized with cyclic voltammetry and amperometry which results the establishment of direct electron transfer between the redox active unit of HRP and the Au surface. Electrochemical measurements reveal that the high biological activity and stability is exhibited by the immobilized HRP and a quasi-reversible redox peak of the redox centre of HRP was observed at about −0.355 and −0.275 V vs. Ag/AgCl. The electron transfer rate constant, KS and electron transfer co-efficient α were found as 0.57 s−1 and 0.42, respectively. Excellent electrocatalytic activity for the reduction of H2O2 was exhibited by the developed biosensor. The proposed biosensor modified with HRP/CNT 3D network displays a broader linear range and a lower detection limit for H2O2 determination. The linear range is from 1.0 × 10−7 to 1.2 × 10−4 M with a detection limit of 2.2.0 × 10−8 M at 3 σ. The Michaelies–Menten constant Kapp M value is estimated to be 0.19 mM. Moreover, this biosensor exhibits very high sensitivity, good reproducibility and long-time stability

Recent advances in gold nanoparticles modified electrodes in electrochemical nonenzymatic sensing of chemical and biological compounds

Gold nanoparticles (Au NPs) are extensively used nanomaterials that have profound relation with diverse sensor development, catalysis and drug delivery due to their remarkable electrochemical properties. It plays its role as the main catalyst, catalyst support, signal amplifier and electrochemical probe during sensing. Here in this review, we have summarised the recently reported nonenzymatic gold nanoparticles-based electrochemical sensing of different chemical and biological molecules. Although there are numerous conventional methods for detecting these compounds, those detection methods are quite complex, costly, and time-consuming. Gold nanoparticles-based electrochemical sensors have emerged as committed alternatives that address these issues while providing a rapid and highly sensitive detection system. Additionally, enzyme-free sensors reduce the shortcomings of enzymatic sensors, accelerating the widespread use of electrochemical sensors. This review will provide information on the process of combining of Au NPs with other molecules during electrode fabrication and the role of Au NPs in chemical and biological molecule detection. The electrocatalytic mechanisms associated with detection are also discussed. Numerous tables summarise critical features, including electrode composition, detection limits (LOD), linear ranges, and real-time applications. The attached schematic tree diagram will give an idea of what other molecule groups can be combined with gold nanoparticles to fabricate the sensor. We hope that this in-depth assessment of gold nanoparticles-based electrochemical sensors will contribute to a better understanding of the role and behaviour of Au NPs in sensing systems and hence to future advanced research

Applications of nanomaterials for biosensor fabrication based on redox enzyme and protein: A mini-review

Redox enzyme and protein modified biosensors are commercially triumphant bioelectronic devices used in the point-of-care analysis. The use of nanotechnology derived nanomaterials during enzyme immobilization creates a synergistic effect by integrating recognition and catalytic properties with the electronic properties of nanomaterials. This synergy improves the sensitivity, conductivity stability, surface-to-volume ratio, selectivity, detection limit and other analytical features. This critical review focuses on the redox enzymes and proteins most frequently used in glucose and hydrogen peroxide sensing, such as horseradish peroxidase (HRP), glucose oxidase (GOx), hemoglobin (HB), and cytochrome C (Cyt c). Besides, we evaluate the state of art of this approach, selection of nanomaterials, preparation and immobilization mechanisms, their role and sensing applications. Besides advantages, we have discussed the pressing challenges of developing these sensors. This review will guide the research community to develop rational and highly efficient nanomaterial immobilized biosensors

Applications of nanomaterials for biosensor fabrication based on redox enzyme and protein: A short review

Redox enzyme and protein modified biosensors are commercially triumphant bioelectronic devices used in the point-of-care analysis. The use of nanotechnology derived nanomaterials during enzyme immobilization creates a synergistic effect by integrating enzyme’s recognition and catalytic properties with the electronic properties of nanomaterials. This synergy improves the biosensor’s sensitivity, conductivity stability, surface-to-volume ratio, selectivity, detection limit and other analytical features. This critical review focuses on the redox enzymes and proteins most frequently used in glucose and hydrogen peroxide sensing, such as horseradish peroxidase (HRP), glucose oxidase (GOx), hemoglobin (HB), and cytochrome C (Cyt c). Besides, we evaluate the state of art of this approach, selection of nanomaterials, preparation and immobilization mechanisms, their role and sensing applications. Besides advantages, the discussions have discussed on the pressing challenges of developing these sensors. This review will guide the research community to develop rational and highly efficient nanomaterial immobilized biosensors

Adhesion and proliferation of living cell on surface functionalized with glycine nanostructures

This research presents the application of glycine amino acid for establishing firm cell-substrate interaction instead of expensive adhesion proteins, peptides and peptide derivatives. The glycine amino acid is chemically functionalized on the coverslip to achieve self-assembled nanostructure. Glycine self-assembly on NaCl treated coverslips is initiated with SiONa+:COO− linkage while their nanostructure is achieved with formation of glycine chain through NH3+:COO− covalent linkage between the adjacent molecules. The functionalization steps are confirmed by Fourier-transform infrared spectroscopy (FTIR) investigation. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations reveal that glycine growth initiates at 4 Hours (H) post-treatment while maximum growth appears after 8H-10H. Both the vertical and horizontal growth of nanostructures show dependence on functionalization periods. Various levels of glycine functionalized surface show different levels of baby hamster kidney (BHK-21) cell adhesion and proliferation efficiency with maximum performance for 10H functionalized surface. The adhesion and proliferation performance of 10H glycine functionalized surface shows negligible difference when compared with glycine-aspartic acid (RGD) functionalized surface. Finally, growth curves obtained from both glycine and RGD functionalized surface reveal exponential growth phage up to 48H followed by stationary phage between 48H and 72H while death of many cells appears from 72H to 96H. Thus, this research concluded that glycine functionalized surface is equally effective for cell adhesion and proliferation

Improved glucose biosensor based on glucose oxidase-horseradish peroxidase/multiporous tin oxide modified-electrode

The fabrication of a crosslinked network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized on glassy carbon electrode (GCE) and its utilization as a sensor for glucose detection has been reported. The 3-D network established with GOx-HRP/SnO2 has possessed high sensitivity and stability by performing the electrocatalytic features in sensing of glucose. The turbidity of fabrication has been scanned and analyzed using UV-Vis Spectroscopy. The morphology and composition of the fabricated GOx-HRP modified multi-nanoporous SnO2 nanofibers were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were used to study the proposed electrochemical biosensor. The effect of applied electrode potential, pH and the concentration of glucose on the sensitivity of the biosensor have been systemically investigated which indicates that these systems should be very useful for other sensing applications

Effects of RF/MW Exposure from Mobile-phone Base-Stations on the Growth of Green Mint Plant using Chl a Fluorescence Emission

We report on the effects of RF/MW on plants.Green Mint plant exposed to different levels ofradiation (from 0.5 to 10.5 μW/cm2) for thispurpose. A USB2000 spectrophotometer wasused to record fluorescence signals from intactleaves.Spectroscopic data (P.I.R and A.R)together with vegetative data (leafdimensions and weight), revealed stressingeffects on plant due to RF/MW in all groupsexcept the control which was free of exposure