Encapsulation of GFP in Complex Coacervate Core Micelles.

Protein encapsulation with polymers has a high potential for drug delivery, enzyme protection and stabilization. Formation of such structures can be achieved by the use of polyelectrolytes to generate so-called complex coacervate core micelles (C3Ms). Here, encapsulation of enhanced green fluorescent protein (EGFP) was investigated using a cationic-neutral diblock copolymer of two different sizes: poly(2-methyl-vinyl-pyridinium)41-b-poly(ethylene-oxide)205 and poly(2-methyl-vinyl-pyridinium)128-b-poly(ethylene-oxide)477. Dynamic light scattering and fluorescence correlation spectroscopy (FCS) revealed a preferred micellar composition (PMC) with a positive charge composition of 0.65 for both diblock copolymers and micellar hydrodynamic radii of approximately 34 nm. FCS data show that at the PMC, C3Ms are formed above 100 nM EGFP, independent of polymer length. Mixtures of EGFP and nonfluorescent GFP were used to quantify the amount of GFP molecules per C3M, resulting in approximately 450 GFPs encapsulated per micelle. This study shows that FCS can be successfully applied for the characterization of protein-containing C3Ms.

Facile one-step synthesis of monodisperse micron-sized latex particles with highly carboxylated surfaces.

A facile method for the aqueous synthesis of monodisperse and micronmeter-sized colloids with highly carboxylated surfaces is presented. The method is applied to three different monomers, styrene, methyl methacrylate, and 2,2,2-trifluoroethyl methacrylate, and illustrate tuning of the size and monodispersity in the reactions. High surface density of carboxylic acids of up to 10 COOH nm(-2) from potentiometric titrations, is achieved through copolymerization with itaconic acid. The versatility of this system is highlighted by creating highly fluorescent and monodisperse particles that can be index matched in aqueous solution and through surface modification via the carboxylic acid groups using standard amidation chemistry.

Translocation of positively and negatively charged polystyrene nanoparticles in an in vitro placental model.

To obtain insight in translocation of nanoparticles across the placental barrier, translocation was studied for one positively and two negatively charged polystyrene nanoparticles (PS-NPs) of similar size in an in vitro model. The model consisted of BeWo b30 cells, derived from a human choriocarcinoma grown on a transwell insert forming a cell layer that separates an apical from a basolateral compartment. PS-NPs were characterized with respect to size, surface charge, morphology and protein corona. Translocation of PS-NPs was not related to PS-NP charge. Two PS-NPs were translocated across the BeWo transwell model to a lower extent than amoxicillin, a model compound known to be translocated over the placental barrier to only a limited extent, whereas one PS-NP showed a slightly higher translocation. Studies on the effect of transporter inhibitors on the translocation of the PS-NPs indicated that their translocation was not mediated by known transporters and mainly dependent on passive diffusion. It is concluded that the BeWo b30 model can be used as an efficient method to get an initial qualitative impression about the capacity of NPs to translocate across the placental barrier and set priorities in further in vivo studies on translocation of NPs to the fetus.

In vitro nanoparticle toxicity to rat alveolar cells and coelomocytes from the earthworm Lumbricus rubellus.

Sensitivity of immune cells (coelomocytes) of Lumbricus rubellus earthworms was investigated for exposure to selected nanoparticles, in order to obtain further insight in mechanisms of effects observed after in vivo C60 exposure. In the in vivo study, tissue damage appeared to occur without accompanying increased immune responses. Coelomocytes exposed in vitro to C60 showed no decrease of their cellular viability, but demonstrated a decrease in gene expression of the cytokine-like protein CCF-1, indicating immunosuppression. Experiments with NR8383 rat macrophage cells and tri-block copolymer nanoparticles were used to compare sensitivity and to demonstrate the usefulness of coelomocytes as a test system for nano-immunotoxicity, respectively. Overall, the results imply that sensitivity towards nanoparticles differs between cell types and nanoparticles. Moreover, this study indicates that injuries in absence of an immune response, observed after in vivo C60 exposure in our earlier work, are caused by immunosuppression rather than coelomocyte mortality.

Monodisperse polymer-virus hybrid nanoparticles.

Self-assembly of polystyrene sulfonate and modified cowpea chlorotic mottle virus protein yields monodisperse icosahedral nanoparticles of 16 nm size.