Particle size and surface charge are key parameters of nanoparticles (NPs), especially therapeutic NPs, to influence the kinetics in vivo and interaction with the cellular and biological membranes and decide the efficacy for biological systems. Characterization of nanomaterials including both nanoparticles and micelles has therefore been a major issue in nanomedicine research to develop well-defined nano-formulations with focus on therapeutic goals. Dynamic light scattering (DLS) and zeta potential (ZP) measurements are widely accepted techniques for proper determination of the particle size and surface charge of therapeutic NPs. These have so far been easy, simple, and reproducible tools. However, there are challenges to interpret and systematically analyze data effectively due to lack of adequate understanding of the principles involved and impeccable background for operation of the system along with competence of sample preparation and characterization and so on. This review addresses the issues with focus on the fundamental principles involved in the techniques of DLS and ZP. The ultimate goal has been development of knowledge–base with a view to better analyzing and interpreting results for evaluation of hydrodynamic size, diffusion, inter particular interactions and stability of colloidal systems based on surface charge of therapeutic NPs. Manuscript profile

Cationic dye Acridine orange (AO) has wide applications especially in biological fields such as analysis of lysosomal and mitochondria content by flow cytometry and so on. In the current work, spectroscopy of acridine orange (AO) dye at both low concentrations (mdye/mwater=6.25*10-5, 3.12*10-5) and high concentrations (mdye/mwater=0.002, 0.001) was studied in confined water nanodroplets within water/AOT/n-hexane microemulsions (MEs) at a constant water content (W= [Water]/[AOT]=10) and as a function of mass fraction of droplet (MFD) using absorption and fluorescence spectroscopic techniques. The absorption spectra of the dye at high concentrations of Acridine orange (AO) dye molecules showed that the absorption spectra of the samples deviated from Beer's law, and are broadened at larger MFD due to the interactions of AO dye molecules. The fluorescence spectrum was investigated at two high concentrations (0.002, 0.001) and low concentrations (6.25*10-5, 3.12*10-5). At high concentration of the dye, quenching of fluorescence intensity was observed due to the accumulation of the dye molecules, coupled with a red shift with increasing MFD. However, in the lower concentration regime, enhancement of fluorescence intensity was observed with increasing MFD. The Stokes’ shift of the dye for both high and low concentrations increased with MFD, but to a greater extent at high concentrations compared to that at low concentrations. Manuscript profile

Fluoride at high concentrations in water is detrimental to human health. To find an efficient means of removal of fluoride from aqueous system, we synthesized magnesium oxide (MgO)- based iron-cobalt-manganese (MgO-FCN ) nanocomposites via co-precipitation. Fluoride adsorption process was optimized by standard software. The effect of independent parameters such as pH (3-11), initial dose of nanoparticle (0.02-0.1 g/L), initial concentration of fluoride (10-50 mg/L) and reaction time (30-180 min) were optimized to obtain the best responses of fluoride removal using statistical Central Composite Design (CCD) in the procedure of response surface modeling. The best conditions were optimized as pH=5, initial concentration of nanoparticle =0.05 g/L, initial concentration of fluoride =50 mg/L and the process time of 90 min. Under these conditions, the removal efficiency of the fluoride by MgO-based nanocomposites was achieved as 84.64%. High correlation coefficients for the proposed model was also obtained (adjusted R2=0.9993 and R2=0.9984). The equilibrium data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The Langmuir model was found to be describing the data best. Kinetic studies showed that the adsorption followed a pseudo-second order reaction. Manuscript profile

Metal oxide nanoparticles due to their antioxidant properties have attracted significant attention and exhibited good potential for use in cancer theranostics. Owing to the poor absorption in the physiological environment, they are an ideal candidate to act as nanocarriers in targeted drug delivery and bioimaging. This feature can be successfully implemented in live monitoring and imaging applications, which offer the possibilities and scope for optical, magnetic resonance, and nuclear imaging. The environment of malignant cells like the rapid proliferation of cells, specific antigen expressions, and leaky tumor vasculature can be used by the modifications in their morphology and surface functionalization. Ceria (CeO2) nanoparticles have been fascinating in this regard. Different properties such as size, agglomeration behavior, and surface charge density facilitate the interaction of nanoparticles with cancer cells. Compared to other nanoparticles, CeO2 nanoparticles have a potential for pharmaceutical use since they can act as a therapeutic agent in different disorders such as cancer, inflammation, and neurodegeneration, due to the ability to exhibit variable oxidation state at the nanoparticle surface. Recent literature reports the eco-friendly or ‘green’ synthesis of CeO2 nanoparticles in which the biological agent acts as stabilizers for a cost-effective and feasible mode of preparation. In this review, we focus on recent literature on CeO2 nanoparticles with an emphasis on the methods of fabrication and biomedical applications. Manuscript profile