Oppositely-charged groups located in the betaine moieties of polycarboxybetaines(PCB) are known to be form stable ion pairs 'inactivating' PCB interaction with polyelectrolytes. Activation of PCB complexing with polyanions was achieved by proper choice of the number n of methylene groups between the betaine charges. The complexing of all the PCB-n studied except PCB-1 was markedly enhanced in neutral and slightly acidic media due to protonation of PCB-n carboxylic groups that occurred with a pH shift of 2 to 3 units as compared with the protonation of free PCB-n. Practical ramifications of the pH stabilisation effect could extend to areas of biotechnology, specifically in bioseparation and gene delivery. 20 refs.

A complex process of asymmetric reduction accompanied by introduction of an adsorbing resin (various Amberlite resins from Rohm & Haas) was applied to the asymmetric reduction of beta-oxo ester by ordinary baker's yeast. The resins slowly released the reaction substrate and in-situ-adsorbed the product, so the concentrations of the substrate and product in the aqueous phase could be controlled according to the adsorption behaviour. The reaction of asymmetric reduction of ethyl 4-chloro-3-oxobutanoate to chiral ethyl 4-chloro-3-hydroxybutanoate(CHBE) was chosen as the typical asymmetric reduction of beta-oxo esters, as it was one of the best models of this type of reaction and the product, a single enantiomer of CHBE, is one of the most important chiral building blocks for many enantiomerically-pure pharmaceuticals. 27 refs.

A summary is presented of the literature on the discovery of 'superquenching' of fluorescent polyelectrolytes, the determination of the factors that influence and control superquenching, and the development of biosensing applications based on fluorescent polymer superquenching. Specific topics covered include superquenching of fluorescence of conjugated polyelectrolytes and related fluorescent polymers, biosensing based on fluorescent polyelectrolyte superquenching, superquenching assays based on nucleic acid hybridisation, superquenching assays for protease enzyme activity, and assays for kinase/phosphatase enzyme activity (metal ion mediated superquenching). 55 refs.

Freeze drying of polymeric nanoparticles with projection coronas resulted in the formation of three-dimensional microconstructs with various morphologies, including hollow microspheres, without a solid or colloidal template. The nanoparticles used were of styrene-co-acrylonitrile-co- poly(ethylene glycol) terpolymers. The microconstructs had sufficient mechanical strength to redisperse successfully in water without collapsing, while they broke into nanoparticles following successive freeze-thawing cycles. The technique could be use for developing nano- and microstructured materials such as drug delivery devices (hollow constructs) and photonic balls with specific light scattering properties. 21 refs.

Multilayered, asymmetric vehicles were constructed with three-dimensional features that could provide the capacity to target cells, promote unidirectional controlled release and enhance permeation across the intestinal epithelial barrier. Three methods of fabrication were used, i.e. a combination of photolithography and reactive ion etching, photolithographic patterning alone and use of polydimethylsiloxane moulding techniques. Particular attention was paid to microfabricated PMMA devices and their specific interactions (post-chemical surface modification) with a human colonic cell line expressing enterocytic differentiation. Other prototypic materials included epoxy resin, poly(DL-lactide-co-glycolide) and gelatin. 37 refs.

The synthesis and physico-chemical characterisation of a biodegradable multiblock polymer drug carrier based on polyethylene glycol is described. The blocks were connected by an enzymatically degradable tripeptide derivative consisting of one lysine and two glutamic acid residues. Doxorubicin was attached to the polymer carrier via a hydrozone bond. Human immunoglobulin G was linked to the complex and characterised by size exclusion chromatography, UV vis spectroscopy, electrophoresis, and amino acid analysis. The antitumour activity of the complex was assessed. 28 refs.

Details are given of the nanoparticles formation between random copolymers of methoxy-polyethylene glycol methacrylate and methacryloylaminopropyltrimethylammonium chloride and oppositely charged surfactants, sodium oleate and sodium laurate. Investigations were carried out using turbidimetric titration, steady-state fluorescence, dynamic light scattering and electron microscopy. Solubility of the nanoparticles were determined. Potential uses in water-soluble drug delivery formulations are mentioned. 67 refs.

Details are given of the preparation of an amphiphilic, hyperbranched aliphatic polyester for use in controlled release drug delivery. The polymer was obtained by the modification of the aliphatic polyester Boltorn H20 with succinic anhydride and then glycidyl methacrylate. The critical association concentration was determined by fluorescence spectroscopy using pyrene as a molecular probe. Particle sizes were determined using light scattering. Daidzein was encapsulated during particle formation and the release properties were determined. 16 refs.

Details are given of the synthesis and properties of polyacrylate gels crosslinked by aluminium ions. The swelling ratio of the gels was measured by changing the solvent pH and adding sodium chloride with different concentrations. Swelling features were explained using a qualitative model based on the ion exchange and the formation of hydrogen bonding. Surface microstructure was observed using atomic force microscopy. The microstructures were analysed in terms of the autocorrelation function and the root-mean-square roughness. 24 refs.

Details are given of the synthesis and properties of a hydrogel system designed for colon targeted drug delivery. The gels were composed of konjac glucomannan copolymerised with acrylic acid and crosslinked with methylene bisacrylamide. The influence of various parameters on the equilibrium swelling ratios of the hydrogels was investigated. The degree of swelling of the gels was modulated by changing crosslinking density of the polymer. The in vitro release of a model drug, aminosalicylic acid was studied. 21 refs.