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Non-specific protein adsorption has a major confounding influence on the in vitroand in vivoperformances of synthetic polymer scaffolds for tissue engineering. For control over cell phenotype to be realised, non-specific protein adsorption needs to be constrained and surfaces modified by immobilisation of specific cell attachment and bioactive molecules. Our aim was to develop biodegradable scaffolds incorporating specific bioactive functionalities, whilst at the same time limiting non-specific protein adsorption by the polymer. The approach we developed was to functionalise PLGA scaffolds with diamino-terminated poly(ethylene glycol) (diamino-PEG), followed by the grafting of heparin to the free –NH2group at the PEG chain end using a coupling agent. The covalent grafting of poly(ethylene glycol) chains both suppressed non-specific protein attachment and provided a substrate for grafting of heparin, onto which growth factors could be tethered and presented to cells in a bioactive configuration. This approach offers a widely applicable solution to overcome the serious and confounding problem of serum fouling of scaffold surfaces, whilst also providing a generic route for specific biofunctionalisation. [ABSTRACT FROM AUTHOR] more...

Emulsion-templated porous polymers (PolyHIPEs) based on polystyrene have been prepared and used for in vitro 3D cell culture of osteoblastic cells. It has been found that the method employed to prepare the emulsion precursor, namely the method of aqueous phase addition, has a significant influence on the homogeneity of the morphology of the material produced as well as the reproducibility of preparation. Addition of the aqueous phase in a controlled manner by means of a syringe pump produced a narrower void size distribution range than addition from a dropping funnel, and the emulsions were obtained in a reproducible manner. Analysis of the morphology of the materials revealed consistency of average void and interconnect diameter, within certain limits. The materials produced were subsequently sectioned into thin membranes which were then mounted to the base of commercially available tissue culture plastic well inserts. Cell culture experiments using MG63 osteoblast-like cells indicated that the materials were capable of supporting cell growth for periods of up to 35 days, producing complex arrangements of cells interacting with one another and the scaffold. The functionality of cells grown on these materials, as indicated by viability assays and the production of biomarkers (alkaline phosphatase and osteocalcin), was found to be enhanced compared to cells grown on 2D substrates. We conclude that the 3D environment produced by these porous materials is more conducive to cell growth in vitro than existing 2D culture plastic. [ABSTRACT FROM AUTHOR] more...

A series of monolithic crosslinked polymers with 2,4,6‐trichlorophenyl acrylate as a reactive component was prepared by free radical polymerization of the internal phases of high internal phase emulsions (HIPEs). The volume ratio of water to oil phase (void volume; 60–90%), crosslinker type (divinylbenzene or ethylenglycol dimethacrylate) and quantity (30–50 mol %) and type of porogenic solvent (chlorobenzene, toluene, chloroform, dichloroethane) were altered to study these effects on the structure and reactivity of the monolithic polymers. The polymer supports were characterized by scanning electron microscopy (SEM), FTIR spectroscopy, elemental analysis and mercury intrusion porosimetry. SEM images revealed an open cellular structure with voids between 1 and 12 μm and window sizes between 0.3 and 3 μm. The porogen had an influence on the surface area, being larger with added porogen and the influence being highest with toluene. Adding toluene also influenced the void size, increasing the average diameter from ∼2 μm (no porogen) to ∼12 μm (added toluene). Monolithic supports were functionalized by reaction of the ester moieties with tris(2‐aminoethyl)amine derivative and by hydrolysis of the ester groups to carboxylic acids. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4043–4053, 2007 [ABSTRACT FROM AUTHOR] more...

Functionalised emulsion-templated polymers (PolyHIPEs) are reported as new materials for electroanalytical applications. PolyHIPEs, which are prepared from high internal phase emulsions (HIPEs), were tailored by optimisation of polymerisation conditions to yield well-defined, tubular, porous membranes. The PolyHIPE membrane backbone was activated by incorporating ionophores, graphite particles, electron mediators and enzymes. The results show that a valinomycin ionophore impregnated, plasticised membrane shows a Nernstian response to K+ ions with improved detection limits and selectivity coefficients compared to traditional PVC membranes. The graphite/mediator/enzyme loaded membranes exhibit quasi-reversible redox behaviour with semi-infinite linear diffusion at fast scan rates tending to radial diffusion at slow scan rates. Additionally, composite, asymmetric membrane structures with a porous PolyHIPE membrane and a PVC membrane exclude proteins such as BSA (bovine serum albumin) and α1 acid glycoprotein (AAG). These preliminary results demonstrate that plasticised membranes with functionalised skeletons and with controllable porosity such as PolyHIPE membranes are very promising for the fabrication of sensors with integrated separation. [ABSTRACT FROM AUTHOR] more...

Glycopolymers are receiving increasing interest due to their application in areas, such as glycomics, medicine, biotechnology, sensors, and separation science. Consequently, new methods for their synthesis are constantly being developed, with an increasing emphasis on the preparation of well‐defined polymers and on the production of complex macromolecular architectures such as stars. This review covers recent developments in the synthesis of glycopolymers, with a particular emphasis on (i) the use of controlled radical polymerization to prepare well‐defined glycopolymers from unprotected monomers and (ii) postpolymerization modification strategies using reactive polymer precursors (including “click” reactions). Recent work on the production of glycosylated polypeptides, which are under investigation as mimics of naturally occurring glycoproteins, is also included. The authors offer some suggestions as to future developments and remaining challenges in this topical area of polymer chemistry. © 2007 Wiley Periodicals, Inc. J Polym Sci PartA: Polym Chem45: 2059–2072, 2007 [ABSTRACT FROM AUTHOR] more...

Binary mixtures of well-defined, stimuli-responsive elastin-based side-chain polymers show a single transition temperature that depends on blend composition. [ABSTRACT FROM AUTHOR]

During the last decade, research and development in microfluidic devices have grown significantly due to their wide variety of applications in physics, chemistry and biology. A specific category of microfluidic devices focuses on the generation of micro-emulsions that can be used, for example, as chemical and biological reactors to synthesize new materials and perform assays. However, the traditional fabrication process of such microfluidic devices involves the use of special instrumentations and clean room facilities. These steps are generally expensive, time consuming and require specific levels of expertise. In this article, an alternative method to fabricate robust microfluidic devices using conventional components and a new commercially available self-setting rubber is presented. Using this method, a cheap, reproducible and easy to manufacture microfluidic device has been developed for generating single and double emulsions in the range of 100s of µm with high throughput. One possible application of this device is demonstrated with the synthesis of highly porous polymer beads from a High Internal Phase Emulsion (HIPE). The fabricated microbeads could find potential application in 3D cell culture due to their high porosity (up to 95%) and pore size (from 5 to 30 µm). The process here presented offers great opportunities for chemists and biologists interested in synthesising new materials while minimizing time, costs and expertise in the development of microfluidic systems. [ABSTRACT FROM AUTHOR] more...