It is at the chemistry-biology interface that this work that we have carried out takes place. Indeed, the expected goal is to develop simple molecules, capable of activating the catalytic action of certain metalloenzymes such as tyrosinase. The official name of an enzyme includes the type of reaction catalyzed, the name of the substrates involved. In this work, we carried out the study of the catalytic activity of the complexes of organotin carboxylates synthesized vis-à-vis the oxidation of 3,5-di-tert-butylcatecchol. The results obtained show that the various complexes exhibit good catalytic activity for the oxidation of 3,5-di-tert-butylcatecchol under mild conditions. The complexes that showed good catalytic activity are the compounds C1 and C2.

Citrus peels are considered as a rich source of valuable biomolecules like pectin as polymer of polysaccharide acid. In this study, response surface methodology was used to optimize pectin extraction from Citrus clementina peels using citric acid as extraction solvent. The effect of parameters conditioning the extraction process and pectin yield (pH, temperature, extraction time, solid/liquid ratio, and raw material particle size) was investigated using a Box-Behnken design. The quality of the extracted pectin was assessed both chemically (moisture, ash, protein, and sugar content) and functionally (gelling power and emulsifying activity). According to the screening experiment, the factors pH, temperature, and particle size were the main factors influencing the pectin yield. The adjusted mathematical model enabled us to plot response surfaces in order to determine optimal extraction conditions. The highest production yield of pectin (26.6%) was obtained at the optimal conditions of: pH = 1.5; temperature 100 °C and particle size = 0.1 mm for an extraction time of 30min. Compared to the predicted value of 26.6%, the experimental extraction yield was about 21.4% of pectin. Concerning the functional properties, the extracted pectin has a high gelling power of 164°SAG and an emulsifying activity of 38.5%.

A biomimetic, ion-imprinted polymer (IIP) was prepared by electropolymerization of pyrrole at the surface of gold electrodes decorated with vertically grown ZnO nanorods. The vertical growth of the nanorods was achieved via an ultrathin aryl monolayer grafted by reduction of diazonium salt precursor. Pyrrole was polymerized in the presence of L-cysteine as chelatant agent and Hg(II) (template). Hg(II)-imprinted polypyrrole (PPy) was also prepared on bare gold electrode in order to compare the two methods of sensor design (Au-ZnO-IIP vs Au-IIP). Non-imprinted PPy was prepared in the same conditions, however in the absence of any Hg2+ template. The strategy combining diazonium salt modification and ZnO nanorod decoration of gold electrodes permitted to increase considerably the specific surface and thus to improve the sensor performances. The limit of detection (LOD) of the designed sensor was ~1 pM, the lowest value ever reported in literature. The dissociation constants between PPy and Hg2+ were estimated at [Kd1 = (7.89 ± 3.63) mM and Kd2 = (38.10 ± 9.22) pM]. The sensitivity of the designed sensor was found to be 0.692 ± 0.034 μA/pM. The Au-ZnO-IIP was found to be highly selective towards Hg(II) compared to cadmium, lead and copper ions. This sensor design strategy could open up new horizons in monitoring toxic heavy metal ions in water and therefore contribute to enhance environmental quality.