Polypropylene nonwoven fabric was surface-activated by high-density oxygen microwave plasma, followed by graft copolymerization with acrylic acid (AAc) and then coupling with chitosan molecules. The pAAc-grafted surface containing C=O in carboxylic acid exhibited a hydrophilic character capable of promoting water absorbency. A larger portion of minimum 85% deacetylated sites in chitosan molecules was then coupled with the grafted pAAc (around 149 microg.cm(-2)) by forming amide bonds at their interface. The covalently bonded chitosan was weighted around 44 microg.cm(-2). The smaller portion of the deacetylated sites demonstrated a distinctive structure as polycations, i.e., NH(3)(+), on the immobilized chitosan. The respective structures following sequential reactions were identified using Fourier transform infrared-attenuated total reflection and X-ray photoelectron spectroscopy with peaks deconvolution. The NH(3)(+) sites on the immobilized chitosan exhibited biofunctional in anticoagulation and in antibacterial property. Blood cells agglutination or agglomeration upon the chitosan-immobilized surface, in particular for red blood cells and platelets, resulted from hydrophilic effect derived from the grafted pAAc and the chitosan itself, and ionic attractions between polycations and blood cells. In addition, the agglutinated cells retained their original morphologies. It is therefore very promising to apply this durable chitosan-immobilized surface for making an antibacterial support, at the same time, for retaining blood cell affinity.

Modification of octadecanethiolate self-assembled monolayers on Au by nitrogen-oxygen or argon-oxygen downstream microwave plasma with a low oxygen content (estimated below several percent) has been studied by synchrotron-based high-resolution X-ray photoelectron spectroscopy and water contact angle measurements. For both types of plasma, the primary processes were found to be the loss of conformational and orientational order and the oxidation of the alkyl matrix and headgroup-substrate interface. At the same time, the film modification occurred much faster and with different intermediates for the nitrogen plasma than for the argon plasma. The reasons for these differences are considered in terms of the different reactivities and different efficiencies of the energy transfer between the plasma constituents in these two types of plasma.

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