Ferrofluids investigated along for about five decades are ultrastable colloidal suspensions of magnetic nanoparticles, which manifest simultaneously fluid and magnetic properties.

The scientific community has made great efforts in advancing magnetic hyperthermia for the last two decades after going through a sizeable research lapse from its establishment. All the progress made in various topics ranging from nanoparticle synthesis to biocompatibilization and in vivo testing have been seeking to push the forefront towards some new clinical trials. As many, they did not go at the expected pace. Today, fruitful international cooperation and the wisdom gain after a careful analysis of the lessons learned from seminal clinical trials allow us to have a future with better guarantees for a more definitive takeoff of this genuine nanotherapy against cancer. Deliberately giving prominence to a number of critical aspects, this opinion review offers a blend of state-of-the-art hints and glimpses into the future of the therapy, considering the expected evolution of science and technology behind magnetic hyperthermia.

Humic acids (HAs) can be dissolved or precipitated in aqueous media, can accumulate at interfaces, can form self-assemblages, can solubilize organic compounds, and can exist in different colloidal states depending on the solution conditions. Because of the randomness of formation, uniform behavior cannot be expected for the composite, polydisperse product, and only trends can be predicted for the properties. I summarize the essence of our previous results related to surface activity, micelle formation, conformational changes, and fractal character with a theoretical approach to explain the joint effect of pH and neutral salts on the colloidal stabilities of humate solutions for HAs with different origins. I present here some newer results based on CPMAS ¹³C-NMR, surface tension, acid-base titration, and colloidal stability investigations of a polydisperse HA sample prepared from peat and its ultrafiltered fractions. By comparing the chemical and colloidal properties of fractions and whole HA, the structural, charge, and aggregation diversities of components have been identified. Characteristic trends have been found in changes of the colloidal state of humic materials and the way in which these changes correlate with the composition of the materials.

Iron oxide nanoparticles are the basic components of the most promising magneto-responsive systems for nanomedicine, ranging from drug delivery and imaging to hyperthermia cancer treatment, as well as to rapid point-of-care diagnostic systems with magnetic nanoparticles. Advanced synthesis procedures of single- and multi-core iron-oxide nanoparticles with high magnetic moment and well-defined size and shape, being designed to simultaneously fulfill multiple biomedical functionalities, have been thoroughly evaluated. The review summarizes recent results in manufacturing novel magnetic nanoparticle systems, as well as the use of proper characterization methods that are relevant to the magneto-responsive nature, size range, surface chemistry, structuring behavior, and exploitation conditions of magnetic nanosystems. These refer to particle size, size distribution and aggregation characteristics, zeta potential/surface charge, surface coating, functionalization and catalytic activity, morphology (shape, surface area, surface topology, crystallinity), solubility and stability (e.g., solubility in biological fluids, stability on storage), as well as to DC and AC magnetic properties, particle agglomerates formation, and flow behavior under applied magnetic field (magnetorheology).

The extensive oxygen-group functionality of single-layer graphene oxide proffers useful anchor sites for chemical functionalization in the controlled formation of graphene architecture and composites. However, the physicochemical environment of graphene oxide and its single-atom thickness facilitate its ability to undergo conformational changes due to responses to its environment, whether pH, salinity, or temperature. Here, we report experimental and molecular simulations confirming the conformational changes of single-layer graphene oxide sheets from the wet or dry state. MD, PM6, and ab initio simulations of dry SLG and dry and wetted SLGO and electron microscopy imaging show marked differences in the properties of the materials that can explain variations in previously observed results for the pH dependent behavior of SLGO and electrical conductivity of chemically modified graphene-polymer composites. Understanding the physicochemical responses of graphene and graphene oxide architecture and performing selected chemistry will ultimately facilitate greater tunability of their performance.

Aqueous dispersions of metal oxide particles are of great practical interest due to their wide-ranging industrial applications and everyday uses under the conditions required. The latter involves the broad variability of pH and dissolved materials among them electrolytes which have definite role in charge neutralization in the vicinity of particle surface. In this work, the pH-dependent surface charging of metal oxides due to the specific adsorption of H + /OH-in the presence of indifferent and specific ions, and other simultaneous processes at solid/water interface such as hydration of surface, dissociation of surface sites, dissolution of solid matrix, then hydrolysis of dissolved ions are discussed. The governing role of solid particles will be showed by means of characteristic examples of aluminum, iron, titanium and zinc oxides, which have significant differences in chemical properties considering e.g., their pH-dependent dissolution and the speciation of dissolved ions.