Inorganic–organic systems with tailored properties controlled on molecular, macromolecular and microscopic level

Abstract

Methods suitable for modification of quartz and glass (plates and beads) on molecular, macromolecular and microscopic levels are described in this paper. The modifications led to composite materials with the core containing quartz (fused silica) or glass and outer shells composed of layers of γ-aminopropyltriethoxysilane (small molecules), dendrimers with aldehyde groups (G5) and/or Starburst PAMAM dendrimers with amino groups (macromolecules), and with one particle thick assemblies of poly(styrene–divinylbenzene–acrolein) microspheres with aldehyde groups at their surface (microscopic objects). Monitoring by AFM quartz plates with immobilized dendrimers revealed that their surfaces are relatively smooth with roughness parameter R g close to 2 nm and with diameters and maximal height of objects covering surface in form of bumps close to 4 nm, i.e. to diameters of single macromolecules of dendrimers. XPS studies of surfaces of modified quartz plates and glass beads unequivocally confirmed attachment of γ-aminopropyltriethoxysilane, dendrimers, and microspheres. Quantitative analysis revealed that dendrimer layers are 3.7 and 3.2 nm thick, for G5 and PAMAM dendrimers, respectively, indicating that these macromolecules form monolayer structures. XPS and SEM studies of quartz surface covered with layers of γ-aminopropyltriethoxysilane, G5 and PAMAM denrimers and subsequently with poly(styrene–divinylbenzene–acrolein) microspheres indicated that saturation of the surface coverage with these particles is achieved at the degree of coverage close to 0.60, i.e. to the maximal value attainable in the case of rapid covalent immobilization of spherical particles. Surfaces of quartz plates and glass beads, with outer layers containing G5 dendrimers and/or poly(styrene–divinylbenzene–acrolein) microspheres and thus, equipped with aldehyde groups, were used for covalent immobilization of human serum albumin (HSA). AFM studies revealed that macromolecules of HSA from dilute protein solution are attached onto surface of G5 dendrimers in such a way that they form clusters composed of not less than 50 protein macromolecules each. X-ray photoelectron spectroscopy used for monitoring of surfaces with immobilized poly(styrene–divinylbenzene–acrolein) microspheres which were subsequently exposed to contact with solution of HSA revealed that macromolecules of HSA are readily attached onto immobilized microspheres.