ABSTRACT:The reactions employed for coupling anti-platelet and other drugs to hydroxylic polymers are described. The drugs include the prostaglandin analogue 5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl) hydantoin (BW 245C) and the phosphodiesterase inhibitors dipyridamole and theophylline. Polymers studied were poly(vinyl alcohol), dextran, and poly(ethylene glycol), and coupling was effected either with the aid of halo-isocyanates or by a two-stage process using carbonyl diimidazole. These novel reaction sequences appear to have wide applications.

We found that the laser irradiated surface of copper substrate becomes fine structure, which we named "surface fine crevice structure". Liquid bismuth on "surface fine crevice structure" of copper substrate occurs "unusual wetting". In the present work, we investigated the wettability of "surface fine crevice structure" of iron substrate by liquid tin, indium and bismuth. "Unusual wetting" appears on laser irradiated surface of iron substrate in case of liquid indium and tin. Whereas, liquid bismuth does not show "unusual wetting" on laser induced iron surface under the present experimental conditions.

This paper is concerned with the activation of platelets by polymers, a keyprocess in the behaviour of prosthetic devices in contact with blood. Platelets are activated by contact with many different types of polymer surfaces, which must therefore be regarded as thrombogenic. Two procedures for reducing thrombogenicity are discussed: (i) the chemical attachment of inhibitors of platelet aggregation and (ii) gross modification of the nature of the surface, e.g. by making it more hydrophilic. For purposes of (i) the potent prostaglandin analogue BW 245C has been used, while for (ii) grafting of poly(ethylene glycol) (PEG) has been explored. Both methods give greatly reduced platelet adhesion in in vitro tests. The second part of the paper deals with the properties of adducts of inhibitors of platelet aggregation (BW 245C, dipyridamole) with water-soluble macromolecules [poly(N-vinyl pyrrolidone), PEG, dextran]. Adducts have been synthesized with terminal and side-chain coupling. On adduction the two inhibitors mentioned show opposite types of behaviour: the molar activity of BW 245C is dramatically reduced, but that of dipyridamole is significantly increased. Remarkable synergistic effects have been recorded for BW 245C adducts. These observations are .interpreted in terms of differences in stereochemistry in the drug-receptor interactions. Appropriate chemical techniques for coupling are outlined, attention being drawn to the special uses of haloalkyl-and haloacyloisocyanates and 2-isocyanatoethyl methacrylate as reagents.

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The low-temperature formation of c-axis-oriented aluminum nitride thin films was demonstrated by plasma-assisted reactive pulsed-DC magnetron sputtering. The effects of the duty cycle at the pulsed-DC voltage applied to the Al target on the properties of AlN films formed via inductively coupled plasma (ICP)-enhanced pulsed-DC magnetron sputtering deposition were investigated. With decreasing duty cycle at the target voltage, the peak intensity of AlN(0002) increased linearly. The surface roughness of AlN films decreased since there was an increase in film density owing to the impact of energetic ions on the films together with the enhancement of nitriding associated with the relative increase in N radical flux. The improvement of both the crystallinity and surface morphology of AlN films at low temperatures is considered to be caused by the difference between the relative flux values of ions and sputtered atoms.