A detailed analysis of biodegradable nanospheres by different techniques--a combined approach to detect particle sizes and size distributions

Method to determine the anisotropy parameter g of a turbid medium

We present a method to determine the anisotropy parameter g of a scattering liquid medium. A simple experimental setup is used to measure the scattered light from turbid samples, and a calibration curve is used to determine g. The interaction coefficient of the medium is experimentally determined, and the calibration curve is obtained through Monte Carlo simulations. The method is tested for nonabsorbing solutions of polystyrene spheres, and the simulation results are found to agree with the experiments.

Nanoparticle Analysis by Online Comprehensive Two-Dimensional Liquid Chromatography combining Hydrodynamic Chromatography and Size-Exclusion Chromatography with Intermediate Sample Transformation

Polymeric nanoparticles have become indispensable in modern society with a wide array of applications ranging from waterborne coatings to drug-carrier-delivery systems. While a large range of techniques exist to determine a multitude of properties of these particles, relating physicochemical properties of the particle to the chemical structure of the intrinsic polymers is still challenging. A novel, highly orthogonal separation system based on comprehensive two-dimensional liquid chromatography (LC × LC) has been developed. The system combines hydrodynamic chromatography (HDC) in the first-dimension to separate the particles based on their size, with ultrahigh-performance size-exclusion chromatography (SEC) in the second dimension to separate the constituting polymer molecules according to their hydrodynamic radius for each of 80 to 100 separated fractions. A chip-based mixer is incorporated to transform the sample by dissolving the separated nanoparticles from the first-dimension online in tetrahydrofuran. The polymer bands are then focused using stationary-phase-assisted modulation to enhance sensitivity, and the water from the first-dimension eluent is largely eliminated to allow interaction-free SEC. Using the developed system, the combined two-dimensional distribution of the particle-size and the molecular-size of a mixture of various polystyrene (PS) and polyacrylate (PACR) nanoparticles has been obtained within 60 min.

Application of flow field-flow fractionation for the characterization of macromolecules of biological interest: a review

An overview is given of the recent literature on (bio) analytical applications of flow field-flow fractionation (FlFFF). FlFFF is a liquid-phase separation technique that can separate macromolecules and particles according to size. The technique is increasingly used on a routine basis in a variety of application fields. In food analysis, FlFFF is applied to determine the molecular size distribution of starches and modified celluloses, or to study protein aggregation during food processing. In industrial analysis, it is applied for the characterization of polysaccharides that are used as thickeners and dispersing agents. In pharmaceutical and biomedical laboratories, FlFFF is used to monitor the refolding of recombinant proteins, to detect aggregates of antibodies, or to determine the size distribution of drug carrier particles. In environmental studies, FlFFF is used to characterize natural colloids in water streams, and especially to study trace metal distributions over colloidal particles. In this review, first a short discussion of the state of the art in instrumentation is given. Developments in the coupling of FlFFF to various detection modes are then highlighted. Finally, application studies are discussed and ordered according to the type of (bio) macromolecules or bioparticles that are fractionated.