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Abstract:For this study, unfunctionalised and functionalised nanoparticles of silica (SiO2) were incorporated into a sol-gel based matrix in an effort to provide more effective corrosion protection on a mild steel substrate. Tests such as atomic force microscopy (AFM) and white light interferometry (WLI) were carried out to characterise coating microstructure and properties. Corrosion protection and coating durability was investigated using differe nt methods which included electrochemical impedance spectroscopy (EIS) and accelerated salt spray testing to simulate a marine environment. Electrochemical test results as well as results after exposure in the neutral salt spray test indicated that the addition of silica nanoparticles led to an improvement in corrosion resistance of the coating matrix. The most effective performance was observed when the nanoparticles were functiona lised. Nanoparticle functionalisation helped to avoid agglomeration during incorporation leading to a more unifo r m nanoparticle distribution within the coating formulation and an improvement of the coating's ability to protect against corrosion.2 Highlights:-The influence of silica (SiO2) nanoparticle incorporation in a sol-gel based coating was studied -SiO2 particle surface treatment improved coating homogeneity and prevented cracking propagation -Corrosion resistance improved with functionalised SiO2 nanoparticles

Although corrosion resistance and mechanical properties of sol-gel coatings have been studied independently, there are limited studies that consider both collectively. However, since any form of mechanical damage could impair the protective function of the coating, it is prudent to consider the mechanical durability of coatings as well as their corrosion resistance. The present work considers the impact of silica nanoparticles on the morphology and mechanical properties of a sol-gel derived coating. The relationships between the results obtained from tests such as atomic force microscopy (AFM), nanoindentation or erosion test with previously reported corrosion results obtained via salt spray or electrochemical impedance spectroscopy (EIS) are discussed. Results show that reinforcing a sol-gel coating with silica nanoparticles and, particularly, functionalised silica nanoparticles led to coatings with improved mechanical properties and enhanced erosion impact resistance. The role of nanoparticles on improving mechanical properties and corrosion resistance, which is of importance within the coating industry, is discussed. Highlights:-Effect of SiO2 on morphology and mechanical properties in a sol-gel coating was studied-SiO2 surface treatment improved mechanical durability and corrosion resistance-Importance of studying mechanical and corrosion resistance properties of coatings has been proved

The direct accumulation of 6-thioguanosine (6-TG) and its electrochemistry has been studied by cyclic voltammetry in different conditions physical and chemical. In a first moment the surface of electrode was modified with gold nanoparticles. This modification was realized by electrodeposition on the active surface of a glassy carbon electrode with a HAuCl 4 solution. The nucleotide 6-thioguanosine was deposited in this gold nanoparticles monolayer. The study of accumulation of other nucleotide, adenosine 5'-monophosphate (AMP), was realized by the direct reaction with 6-TG deposited. The conditions of the reaction and its electrochemical response were tested to fix the ideal conditions of its determination. The ideal conditions of formation of the monolayer and its electrochemical response were studied; the possibility of preconcentration of 6-TG nucleotide in gold nanoparticles, the possibility of catalysis and limits of identification and quantification were also determined. The method proposed can be applied in direct determination of oligonucleotides. In this respect we applied it in the determination of AMP in a commercial product of infantile nutrition.