Characterization techniques for studying the properties of nanocarriers for systemic delivery

Nanocarriers have attracted a huge interest in the last decade as efficient drug delivery systems and diagnostic tools. They enable effective, targeted, controlled delivery of therapeutic molecules while lowering the side effects caused during the treatment. The physicochemical properties of nanoparticles determine their in vivo pharmacokinetics, biodistribution and tolerability. The most analyzed among these physicochemical properties are shape, size, surface charge and porosity and several techniques have been used to characterize these specific properties. These different techniques assess the particles under varying conditions, such as physical state, solvents etc. and as such probe, in addition to the particles themselves, artifacts due to sample preparation or environment during measurement. Here, we discuss the different methods to precisely evaluate these properties, including their advantages or disadvantages. In several cases, there are physical properties that can be evaluated by more than one technique. Different strengths and limitations of each technique complicate the choice of the most suitable method, while often a combinatorial characterization approach is needed

The preparation of carbon nanotube/poly(ethylene oxide) composites using amphiphilic block copolymers

Polymer/multiwall carbon nanotube (MWCNT) composites were prepared by using amphiphilic block copolymers as dispersant. First, MWCNTs were wrapped with amphiphilic block copolymers in aqueous solution. Poly(ethylene oxide) was selected as the hydrophilic block because of its strong affinity with water while one of the following polymers: poly(ethylene), poly(butadiene), poly(styrene), poly(propylene oxide), or poly(thiophene) was used as the hydrophobic block of the copolymers. The dispersions were characterized by optical microscopy and transmission electron microscopy along with UV-Visible adsorption and dynamic light scattering. Based on the results, we could assess the effect on CNT dispersion quality of both, the molar mass of copolymers, the nature of the hydrophobic block and the length of hydrophilic block. The crystallization behavior of composites prepared from these dispersions was investigated. Results were related to the dispersion of the nanoparticles in the polymer matrix