Gold nano-particle modified silica monolithic micro-columns for selected chromatographic and biological applications.

Monolithic microcolumns and especially silica monoliths are showing several advantages compared to classical particle packed and organic polymeric monolithic columns: ease of production and functionalisation, excellent mechanical and thermal stability. Morphology of the monolithic columns can easily be tuned by simply changing the compositions of reaction mixtures. High porosity and interconnected flow-through pores ensure low back pressures at higher flow rates so increasing reaction speeds. High salt resistance allows use water based buffer solutions without any swelling of the stationary phase, large biomolecules can be utilised and conditions to prevent denaturation and comformation changes of these biomolecules can be maintained. Introduction of gold nano-particles on the surfaces of silica monoliths allows increase of the surface areas and alows creation of new, exotic surfaces. Gold shows strong affinity towards thiol groups, which can be found in different biomolecules so utilisation of this phenomena would allow production of micro-reactors and bioreactors in order to mimic biological reactions happening in living organisms and large biological systems. Silica monoliths were synthesised using classical sol-gel process. In order to immobilise gold nano-particles, surfaces of the silica monoliths were amminated using standard silanisation reaction with 3-aminopropyl-methyl-diethoxysilane. 20 nm citrate stabilised gold nano-particles were immobilised on the surfaces afterwards. Depending on the desired application, gold nano-oparticle modified silica monoliths were functionalised afterwards. Immobilisation of ionic species such as amino acids and small peptides would allow creation of stationary phase for ion chromatography, retention of enzymes and other biologically active molecules would allow to create micro-reactors. Leaving gold nano-particles unmodified would make ideal stationary phase for micro-extraction. These modified monoliths were characterised using microscopy techniques, such as scanning electron microscopy (SEM) and field emission SEM. They were used to characterise morphology of the monoliths as well as to evaluate the coverage of the surface with gold nano-particles. The fabricated stationary phases were used for selected biological and chromatographic applications (incorporanting classical chromatographic techniques in order to evaluate the performance of these new modified monolithic materials)