Oxidative degradation of dipeptide (glycyl–glycine) by water-soluble colloidal manganese dioxide in the aqueous and micellar media

Potential application of Micellar nanoreactor for electron transfer reactions mediated by a variety of oxidants: A review

Surfactant, either natural or synthetic, forms a different type of aggregates among which 'Micelle' is truly an important dynamic surfactant aggregate, having a different region to interact with several organic, inorganic, and biomolecules; therefore the practical use of micelle is rapidly growing day-to-day. Surfactant-micelle, looks like a reactor of nano-dimension, govern a variety of reactions in aqueous media extensively. Oxidation is one of the vital reaction, take a part in the course of several organic transformations which are not very easy to execute in water media alone due to the solubility problem. Moreover, in order to achieve a quick transformation overcoming several difficulties the utility of micellar media became an excellent innovation, that's why nowadays, the surfactant and its aggregates are a focus of interest to the researcher of synthetic field and thus its practical applicability has been tremendously cultivated over the few decades. It is, therefore, useful to introduce some basic concepts regarding the aggregation of surfactants. Subsequently, we emphasize the importance of micellar media on the kinetics of oxidation reactions mediated by several metal ions with a special emphasis on their catalytic role.

Degradative treatment of bispyribac sodium herbicide from synthetically contaminated water by colloidal MnO2 dioxide in the absence and presence of surfactants

Bispyribac sodium (BS) is one of the most commonly used herbicides used to kill selectively unwanted herbs particularly in rice plantation. However, the increasing use of herbicides in agricultural field is associated with a potential risk to water resources and aquatic system. Thus, the treatment of such pesticides after fulfillment of their herbicidal activity is of quite interest to minimize the contamination of water. The degradation kinetics of BS from synthetic contaminated water by water-soluble colloidal MnO₂ in acidic medium (HClO₄) has been studied spectrophotometrically in the absence and presence of different surfactants. The degradation has been observed to be fractionally ordered in both BS and HClO₄ under pseudo-first-order reaction condition with respect to MnO₂. The anionic surfactant (sodium dodecyl sulfate) has been observed to be ineffective whereas the cationic surfactant (cetyltrimethyl ammonium bromide) causes flocculation with oppositely charged colloidal MnO₂ and therefore could not be studied further. However, the non-ionic surfactant (Triton X-100) has been observed to accelerate the reaction rate. The catalytic effect of this surfactant has been analyzed and discussed in the light of the available mathematical model. The kinetic data have been used to generate the various activation parameters accompanying the degradation process of BS in the absence and presence of the non-ionic surfactant, Triton X-100.

Modeling of the Inhibitory Effect of Nanoparticles on Amyloid β Fibrillation

Experiments have shown that charged nanoparticles (NP) inhibit, partially or completely, the aggregation of Aβ protein monomers into fibrils. The equilibrium fibril content is found to be inversely proportional to the concentration of NP. In this work, we report a kinetic model for the fibrillation of Aβ protein in the presence of NP. In the model, apart from nucleation, elongation and fragmentation processes, the effect of NP is considered to cause a conformational change to the protein monomer, making the latter incompatible for aggregation. The simulated results explain the growth kinetics of pure Aβ (1-40) protein, and the kinetics in the presence of NP. The NP-monomer interaction considered in the model captures the significant effect of NP on the fibrillation process at a very molar ratio (NP to Aβ monomer) as low as 10^-4. The model predictions are compared with two different NP systems, namely, gold and silica NP. The model can be applied to explain the inhibitory effect of other additives such as small molecules, NP, lipids, and surfactants that show a similar inhibition trend for fibril formation of Aβ and other proteins.

Oxidative degradation of l-histidine by manganese dioxide (MnO2) nano-colloid in HClO4 medium with/without using TX-100 catalyst: a kinetic approach

The kinetics of the oxidative degradation of l-histidine (His) in perchloric acid medium by freshly prepared manganese dioxide (MnO₂) nano-colloid have been investigated with and without using TX-100 catalyst.