New Approaches to the Synthesis and Stabilization of Polymer Microspheres with a Narrow Size Distribution.

This article presents the results of investigations on heterophase polymerization of vinyl monomers in the presence of organosilicon compounds of different structures. On the basis of the detailed study of the kinetic and topochemical regularities of the heterophase polymerization of vinyl monomers, the conditions for the synthesis of polymer suspensions with a narrow particle-size distribution using a one-step method have been determined.

Fabrication of moldable chitosan gels via thermally induced phase separation in aqueous alcohol solutions.

Wide application of chitosan in modern technologies is limited by the lack of reliable and low-cost techniques to prepare size-tuned constructs with a complex surface morphology, improved optical and mechanical properties. We report a new simple method for preparation of transparent thermoreversible chitosan alcogels from chitosan/H2O/ethanol ternary systems. This method, termed "low temperature thermally induced phase separation under non-freezing conditions" (LT-TIPS-NF), fine tunes gelation by adjusting only temperature (from 5 to -25 °C) and varying the initial content of chitosan (from 0.5 to 2.0 wt%) and ethanol (from 28.5 to 47.5 vol%). Transparent non-swelling final constructs of complex shape are prepared by fixing the pre-formed alcogels with a base solution. The size of the gel constructs is limited only by the dimensions of the mold and the cooling chamber. The LT-TIPS-NF is applicable both in injection molding and 3D printing techniques. The in vitro and in vivo experiments show the absence of prominent cytotoxicity and well-defined cell adhesion on the obtained hydrogels. Thus, this facile and scalable technique provides the multifunctional chitosan gel preparation with easily controlled properties exploiting inexpensive, renewable, and environmentally friendly source polysaccharide. These materials have prospects for a variety of uses, especially for biomedical applications.

Multichannel hydrogel based on a chitosan-poly(vinyl alcohol) composition for directed growth of animal cells.

In this study, a new method for production of hydrogels with oriented multichannel structure based on chitosan-poly(vinyl alcohol) compositions was developed. Microscopic and biological studies of the obtained hydrogels were conducted to determine the optimal composition, which would ensure that structure of the material mimics that of the epineurium and perineurium in a nerve. Structure of the hydrogels was adjusted by variation of the initial concentration of the precipitant, poly(vinyl alcohol), and acid in the chitosan compositions. A single cycle of freezing and thawing of the produced hydrogels resulted in lower structural heterogeneity, which is promising for the production of a scaffold that simulates the structure of the native peripheral nerve. in vitro cytotoxic assays showed biocompatibility of the manufactured hydrogels.

Fluoroplast-polyaniline-coated adsorbent for one-step isolation of DNA for PCR detection of viral hepatitides (HBV and TTV).

AIMS: To demonstrate the effectiveness of application of the adsorbent successively modified with nano-layers of fluoroplast and polyaniline for one-step isolation of DNA of hepatitis B virus and transfusion-transmitted virus from human serum. MATERIALS & METHODS: The technique is based on the application of the spin-cartridges containing porous adsorbent for one-step viral DNA isolation from serum followed by polymerase chain reaction. RESULTS: The developed adsorbent was shown to be effective for one-step isolation of viral DNA from serum samples for polymerase chain reaction diagnostics. CONCLUSION: The effectiveness of the developed adsorbent application for isolation of viral DNA from serum for polymerase chain reaction diagnostics was confirmed in comparison with standard methods. Thus, the facile sample preparation method of viral DNA isolation was elaborated.

Quantum dot-containing polymer particles with thermosensitive fluorescence.

Composite polymer particles consisting of a solid poly(acrolein-co-styrene) core and a poly(N-vinylcaprolactam) (PVCL) polymer shell doped with CdSe/ZnS semiconductor quantum dots (QDs) were fabricated. The temperature response of the composite particles was observed as a decrease in their hydrodynamic diameter upon heating above the lower critical solution temperature of the thermosensitive PVCL polymer. Embedding QDs in the PVCL shell yields particles whose fluorescence is sensitive to temperature changes. This sensitivity was determined by the dependence of the QD fluorescence intensity on the distances between them in the PVCL shell, which reversibly change as a result of the temperature-driven conformational changes in the polymer. The QD-containing thermosensitive particles were assembled with protein molecules in such a way that they retained their thermosensitive properties, including the completely reversible temperature dependence of their fluorescence response. The composite particles developed can be used as local temperature sensors, as carriers for biomolecules, as well as in biosensing and various bioassays employing optical detection schemes.

Submicron polymer particles containing fluorescent semiconductor nanocrystals CdSe/ZnS for bioassays.

AIM: This study aimed to design a panel of uniform particulate biochemical reagents and to test them in specific bioassays. These reagents are polymer particles of different sizes doped with semiconductor nanocrystals and conjugated with either full-size antibodies or recombinant mini-antibodies (4D5 scFv fragment) designed by genetic engineering approaches. MATERIALS & METHODS: A panel of highly fluorescent polymer particles (150-800 nm) were formed by embedding CdSe/ZnS nanocrystals (quantum dots) into preformed polyacrolein and poly(acrolein-co-styrene) particles. Morphology, content and fluorescence characteristics of the prepared materials were studied by laser correlation spectroscopy, spectrophotometry, optical and fluorescent microscopy and fluorimetry. RESULTS: The obtained fluorescent particles sensitized by anti-Yersinia pestis antibodies were used for rapid agglutination glass test suitable for screening analysis of Y. pestis antigen and for microtiter particle agglutination, which, owing to its speed and simplicity, is very beneficial for diagnostic detection of Y. pestis antigen. Recombinant 4D5 scFv antibodies designed and conjugated with polymer particles containing quantum dots provide multipoint highly specific binding with cancer marker HER2/neu on the surface of SKOV-3 cell.

Novel composite matrices modified with nanolayers of polymers as perspective materials for separation of biomolecules and bioanalysis.

AIMS: A new approach for the preparation of adsorbents for one-step isolation/purification of DNA from different samples (e.g., bacterial lysates, smears and blood) has been developed. MATERIALS & METHODS: The technique is based on the use of porous silica preliminary treated with ozone followed by grafting of polymer nanolayers on the activated carrier surface. The chemical nature of active centers, their stability and conditions for the use of the activated support as heterogeneous initiator of different macromolecular reactions were studied. RESULTS: The adsorbents modified with thin (~3.0-7.5 nm) polytetrafluoroethylene and polyaniline layers were prepared and characterized. Sorption properties of the obtained adsorbents were demonstrated on examples of express (2-5 min) one-step DNA isolation for direct use in PCR diagnostics. CONCLUSION: The effectiveness of the developed adsorbents used for DNA isolation and purification was confirmed in comparison with the standard methods. Thus, a facile (alternative in relation to irradiation postpolymerization or standard oxidative polymerization techniques) manufacturing method of the materials for nucleic acids sample preparation was developed.