Advances in Colloid and Interface Science (v.201-202, #C)

Advances in nanomedicines for malaria treatment by N.P. Aditya; P.G. Vathsala; V. Vieira; R.S.R. Murthy; E.B. Souto (1-17).
Malaria is an infectious disease that mainly affects children and pregnant women from tropical countries. The mortality rate of people infected with malaria per year is enormous and became a public health concern. The main factor that has contributed to the success of malaria proliferation is the increased number of drug resistant parasites. To counteract this trend, research has been done in nanotechnology and nanomedicine, for the development of new biocompatible systems capable of incorporating drugs, lowering the resistance progress, contributing for diagnosis, control and treatment of malaria by target delivery. In this review, we discussed the main problems associated with the spread of malaria and the most recent developments in nanomedicine for anti-malarial drug delivery.The main factor that contributes to the success of malaria proliferation is the increased number of drug resistant parasites. To counteract this trend, research has been done in nanotechnology and nanomedicine, for the development of new biocompatible systems capable of incorporating drugs, lowering the resistance progress, contributing for diagnosis, control and treatment of malaria by target delivery. This scheme represents the sequential steps involved in the development of anti-malarial drugs.Display Omitted
Keywords: Malaria; Plasmodium; Nanomedicine; Colloidal carriers; Toxicity; Microfluidics; Lipids; Polymers; Solid lipid nanoparticles; Liposomes; Dendrimers;

Exocytosis of nanoparticles from cells: Role in cellular retention and toxicity by Ramin Sakhtianchi; Rodney F. Minchin; Ki-Bum Lee; Alaaldin M. Alkilany; Vahid Serpooshan; Morteza Mahmoudi (18-29).
Over the past decade, nanoparticles (NPs) have been increasingly developed in various biomedical applications such as cell tracking, biosensing, contrast imaging, targeted drug delivery, and tissue engineering. Their versatility in design and function has made them an attractive, alternative choice in many biological and biomedical applications. Cellular responses to NPs, their uptake, and adverse biological effects caused by NPs are rapidly-growing research niches. However, NP excretion and its underlying mechanisms and cell signaling pathways are yet elusive. In this review, we present an overview of how NPs are handled intracellularly and how they are excreted from cells following the uptake. We also discuss how exocytosis of nanomaterials impacts both the therapeutic delivery of nanoscale objects and their nanotoxicology.Display Omitted
Keywords: Exocytosis; Nanoparticles; Nanotoxicology; Therapeutic delivery;

Nanomedicine is a rapidly emerging interdisciplinary field in which medicine is coupled with nanotechnology tools and techniques for advanced therapy with the aid of molecular knowledge and its associated treatment tools. This field creates a myriad of opportunities for improving the health and life of humans. Unchecked chronic inflammation, oxidative stress, and free-radical damage causes proportionate aging and other related diseases/disorders. Antioxidants act as free radical scavengers, singlet oxygen (1O2) quenchers, peroxides and other ROS inactivators, as well as metal ion chelators, quenchers of secondary oxidation products and inhibitors of pro-oxidative enzymes. Nanoparticles possessing antioxidative properties have recently emerged as potent therapeutic agents owing to their potential applications in life sciences for improvement of the quality of life and longevity. Accordingly, the use of antioxidant nanoparticles/nanomaterials is burgeoning in biomedical, pharmaceutical, cosmetic, food and nutrition fields. Due to the smaller size, greater permeability, increased circulation ability and biocompatibility of these nanoparticles to alleviate oxidative stress, they have become indispensable agents for controlling aging and its associated pathologies, including neurodegenerative diseases, cardiovascular diseases, and pulmonary diseases. This review discusses antioxidant nanoparticles, which are nano-dimensioned metals, non-metals, metal oxides, synthetic and natural antioxidants and polymers, and the molecular/biochemical mechanisms underpinning their activities.Display Omitted
Keywords: Nanoparticles; Antioxidants; Nanomedicine; Inflammation; Longevity; Oxidative stress; Free radicals;

Knowledge about the behavior and reactions of separate soil components with trace elements (TEs) and their distribution coefficients (K ds) in soils is a key issue in assessing the mobility and retention of TEs. Thus, the fate of TEs and the toxic risk they pose depend crucially on their K d in soil. This article reviews the K d of TEs in soils as affected by the sorption system, element characteristics, and soil colloidal properties. The sorption mechanism, determining factors, favorable conditions, and competitive ions on the sorption and K d of TEs are also discussed here. This review demonstrates that the K d value of TEs does not only depend on inorganic and organic soil constituents, but also on the nature and characteristics of the elements involved as well as on their competition for sorption sites. The K d value of TEs is mainly affected by individual or competitive sorption systems. Generally, the sorption in competitive systems is lower than in mono-metal sorption systems. More strongly sorbed elements, such as Pb and Cu, are less affected by competition than mobile elements, such as Cd, Ni, and Zn. The sorption preference exhibited by soils for elements over others may be due to: (i) the hydrolysis constant, (ii) the atomic weight, (iii) the ionic radius, and subsequently the hydrated radius, and (iv) its Misono softness value. Moreover, element concentrations in the test solution mainly affect the K d values. Mostly, values of K d decrease as the concentration of the included cation increases in the test solution. Additionally, the K d of TEs is controlled by the sorption characteristics of soils, such as pH, clay minerals, soil organic matter, Fe and Mn oxides, and calcium carbonate. However, more research is required to verify the practical utilization of studying K d of TEs in soils as a reliable indicator for assessing the remediation process of toxic metals in soils and waters.MS: Mono-sorption system; CS: competitive sorption system; Fluvial: fluvial soil (Entisols); Lacus: Lacustrine soil (Entisols); Marine: sandy soil (Entisols); Aridis: Aridisols; Entis: Entisols; Vertis: Vertisols; Mollis: Mollisols; Histos: Histosols; Alfis: Alfisols.Effect of soil types on Cd and Zn distribution coefficient, K d medium (L kg− 1) under mono-metal and competitive sorption system.Display Omitted
Keywords: Distribution coefficient; Soil trace elements; Sorption system; Soil properties;

Electrokinetic investigations in nanoparticle suspensions in aqueous media are most often performed assuming that the liquid medium is a strong electrolyte solution with specified concentration. The role of the ions produced by the process of charging the surfaces of the particles is often neglected or, at most, the concentrations of such ions are estimated in some way and added to the concentrations of the ions in the externally prepared solution. The situation here considered is quite different: no electrolyte is dissolved in the medium, and ideally only the counterions stemming from the particle charging are assumed to be in solution. This is the case of so-called salt-free systems. With the aim of making a model for such kind of dispersions as close to real situations as possible, it was previously found to consider the unavoidable presence of H+ and OH coming from water dissociation, as well as the (almost unavoidable) ions stemming from the dissolution of atmospheric CO2. In this work, we extend such approach by considering that the chemical reactions involved in dissociation and recombination of the (weak) electrolytes in solution must not necessarily be in equilibrium conditions (equal rates of forward and backward reactions). To that aim, we calculate the frequency spectra of the electric permittivity and dynamic electrophoretic mobility of salt-free suspensions considering realistic non-equilibrium conditions, using literature values for the rate constants of the reactions. Four species are linked by such reactions, namely H+ (from water, from the – assumed acidic – groups on the particle surfaces, and from CO2 dissolution), OH (from water), HCO3 and H2CO3 (again from CO2). A cell model is used for the calculations, which are extended to arbitrary values of the surface charge, the particle size, and particle volume fraction, in a wide range of the field frequency ω. Both approaches predict a high frequency relaxation of the counterion condensated layer and a Maxwell–Wagner–O'Konski electric double layer relaxation at intermediate frequencies. Also, in both cases an inertial decay of the electrophoretic mobility at high ω takes place. The most significant difference between the present model and previous results based on the equilibrium hypothesis is by no means negligible: only in non-equilibrium conditions do we find a low-frequency relaxation (mostly noticed in permittivity data, while its significance is lower in dynamic mobility spectra). This new relaxation presents all the characteristic features of the concentration polarization (or alpha) dispersion. These are: i) the average electric polarization of the system increases when the relaxation frequency is surpassed, contrary to the behavior after Maxwell–Wagner type relaxations; ii) the amplitude of the relaxation increases with surface charge, reaching a sort of saturation if the charge is too high; iii) the relaxation frequency increases with volume fraction while the relaxation amplitude decreases; iv) the characteristic frequency is reduced by the increase in particle radius. All these facts confirm that the non-equilibrium approach seems to better describe the physics of the system by giving rise to a concentration polarization kind of relaxation, only possible when ions can accumulate on both sides of the particles as dictated by the field, and not as determined by equilibrium conditions in the dissociation–recombination reactions involved.Display Omitted
Keywords: Salt-free suspensions; Cell models; Dynamic electrophoretic mobility; Electric permittivity; Alpha and Maxwell–Wagner relaxation;

Magnetic chitosan composites (MCCs) are a novel material that exhibits good sorption behavior toward various toxic pollutants in aqueous solution. These magnetic composites have a fast adsorption rate and high adsorption efficiency, efficient to remove various pollutants and they are easy to recover and reuse. These features highlight the suitability of MCCs for the treatment of water polluted with metal and organic materials. This review outlines the preparation of MCCs as well as methods to characterize these materials using FTIR, XRD, TGA and other microscopy-based techniques. Additionally, an overview of recent developments and applications of MCCs for metal and organic pollutant removal is discussed in detail. Based on current research and existing materials, some new and futuristic approaches in this fascinating area are also discussed. The main objective of this review is to provide up-to-date information about the most important features of MCCs and to show their advantages as adsorbents in the treatment of polluted aqueous solutions.Display Omitted
Keywords: Chitosan; Magnetic chitosan; Chitosan composites; Magnetic composites; Biocomposites; Polysaccharides; Adsorption; Magnetic adsorbents; Magnetic materials; Metals; Dyes; Water pollution;

Electrokinetics of non-Newtonian fluids: A review by Cunlu Zhao; Chun Yang (94-108).
This work presents a comprehensive review of electrokinetics pertaining to non-Newtonian fluids. The topic covers a broad range of non-Newtonian effects in electrokinetics, including electroosmosis of non-Newtonian fluids, electrophoresis of particles in non-Newtonian fluids, streaming potential effect of non-Newtonian fluids and other related non-Newtonian effects in electrokinetics. Generally, the coupling between non-Newtonian hydrodynamics and electrostatics not only complicates the electrokinetics but also causes the fluid/particle velocity to be nonlinearly dependent on the strength of external electric field and/or the zeta potential. Shear-thinning nature of liquids tends to enhance electrokinetic phenomena, while shear-thickening nature of liquids leads to the reduction of electrokinetic effects. In addition, directions for the future studies are suggested and several theoretical issues in non-Newtonian electrokinetics are highlighted.Display Omitted
Keywords: Non-Newtonian electrokinetics; Non-linear electrokinetic phenomena; Electroosmosis; Electrophoresis; Viscoelectric effect; Electrorheological fluids; Microfluidics;