Artur Rozanski

Confined Crystallization of Polyethylene Oxide in Nanolayer Assemblies

The design and fabrication of ultrathin polymer layers are of increasing importance because of the rapid development of nanoscience and nanotechnology. Confined, two-dimensional crystallization of polymers presents challenges and opportunities due to the long-chain, covalently bonded nature of the macromolecule. Using an innovative layer-multiplying coextrusion process to obtain assemblies with thousands of polymer nanolayers, we discovered a morphology that emerges as confined polyethylene oxide (PEO) layers are made progressively thinner. When the thickness is confined to 20 nanometers, the PEO crystallizes as single, high-aspect-ratio lamellae that resemble single crystals. Unexpectedly, the crystallization habit imparts two orders of magnitude reduction in the gas permeability.

Photosensitive nanocapsules for use in imaging from poly(styrene-co-divinylbenzene) cross-linked with coumarin derivatives.

The study objective was to generate biocompatible probes and develop a stable macromolecule imaging system that are based on nanolipopolymersomes and can be used in living cells. We synthesized nanolipopolymersomes with a fluorescent polymer wall surrounded by an outer phospholipid shell that exhibits potential for the controlled delivery of diagnostic agents to cells. We describe a new type of probe suitable for dual detection methods (spectrophotometric and fluorescence). This aspect makes it unique among currently available probes because allows it to be detected with greater accuracy. We developed a highly fluorescent coumarinated polymer to overcome the limited brightness of conventional dyes with insufficient for long-term photostablility. Hydrophilic dyes (Lucifer yellow, Procion red, Procion blue) are entrapped in the aqueous core of stable polymeric nanocapsules with coumarin 6 embedded in a nanometre-thick poly(styrene-co-divinylbenzene) wall. Target compounds can be incorporated into nanocapsules in a single step. The hydrophilic phospholipids outer shell ensures biocompatibility and facilitates cell penetration. In this way, the novel fluorescent hybrid materials can help of nanotechnology.

Morphology, thermal and mechanical properties of polypropylene/SiO2 nanocomposites obtained by reactive blending

The isotactic polypropylene – modified silica (iPP/SiO2) hybrid nanocomposites, obtained by grafting polypropylene chains on amine-functionalized silica particles during reactive blending, were studied. It was found that use of amine-functionalized silica and PP-g-MA as a compatibilizer improved dispersion of nanoparticles. Nanosilica, especially surface-modified, revealed some nucleation activity towards iPP, manifesting in an increase of the crystallization temperature and reduction of spherulite size. iPP/silica nanocomposites exhibit highly improved thermo-oxidative stability, due to formation of a silica protective layer, limiting the polymer volatilization rate. Nanocomposites demonstrate enhanced stiffness and strength, but at higher silica content the ductility is nearly lost due to presence of big agglomerates, acting as critical-sized structural flaws. At low silica concentrations dispersion was improved and big agglomerates were not observed. Consequently, iPP/PP-g-MA/am-SiO2 nanocomposites with low silica content demonstrate high ductility and enhanced impact resistance, related to reinforcing effect of well dispersed silica particles.

Chlorambucil labelled with the phenosafranin scaffold as a new chemotherapeutic for imaging and cancer treatment

Here we report the first of the phenosafranin-chlorambucil conjugate as a new type of a chemotherapeutic agent suitable for dual detection methods (spectrophotometric and fluorescence) in imaging systems and cancer treatment. The synthetic cationic dye (3,7-diamino-5-phenylphenazinium chloride) is used as a fluorescent light-triggered scaffold that acts as a carrier for an anti-cancer drug. The chlorambucil was attached covalently via amide bonds to the bifunctional fluorophore, which facilitates tracking with visible light. Our studies revealed that the new photosensitive compound exhibits improved intrinsic activity in vitro in HeLa cells culture experiments; thus it could be a potential anti-cancer candidate in theranostic drug-delivery systems. In light of the urgent need for in vivo monitoring of the biodistribution of anti-cancer drugs, this strategy for the synthesis of innovative conjugates based on the phenosafranin backbone offers a promising possibility for drug control in anti-cancer therapy and diagnosis. This aspect makes the phenosafranin-chlorambucil conjugate unique among currently available biomarkers.