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

Fast and high resolution mapping of elastic properties of biomolecules and polymers with bimodal AFM

[EN] Fast, high resolution and wide elastic modulus range mapping of heterogeneous interfaces represents a major goal of atomic force microscopy (AFM). This goal becomes more challenging when the nanomechanical mapping involves biomolecules in their native environment. Over the years, several AFM-based methods have been developed to address that goal. However, none of those methods combine sub-nanometer spatial resolution, quantitative accuracy, fast data acquisition speed, wide elastic modulus range and operation in physiological solutions. Here we present detailed protocols to generate high resolution maps of the elastic properties of biomolecules and polymers by using bimodal AFM. The method is fast because the elastic modulus, deformation and topography images are obtained simultaneously. The method is efficient because just a single data point per pixel is needed to generate the above images. In addition, by knowing the deformation, bimodal AFM enables to reconstruct the true topography of the surface.European Research Council (ERC–AdG–340177; 3DNanoMech) and grants CSD201000024 and MAT2016-76507-R from the Ministerio de Economía y Competitividad. This work received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie grant agreement 721874 (SPM2.0). We also acknowledge fellowships FPU15/04622 (C.A.A.) and BES-2017-081907 (V.G.G.) from the Ministerio de Educación.Peer reviewe