Biomimetic silica synthesis and its applications to surfaces and cells

Abstract

The nanometer-scaled control of silica thin films is one of the direct routes to the realization of various applications, including biomedicine, biosensors, heterogeneous catalysis, cell culture, and wettability. In the past decade, biomimetic silica synthesis, found in diatoms and glass sponges, has been investigated as a potential method for cost-effective and low-energy fabrication of silica films. While conventional fabrication methods involve harsh conditions, such as high temperature, extreme pH, and presence of caustic reagents, biomimetic methods?utilizing peptides/proteins found in nature or synthetic polymers as catalytic templates?are considered advantageous for facilely generating and controlling silica thin films under physiologically mild conditions (at near neutral pH and room temperature). In chapter 1, structures of silica films were controlled in a nanometer scale by simple counteranion exchange of quaternized poly(2-(dimethyl amino)ethyl methacrylate) (q-PDMAEMA). As the charge density of counteranion decreased ($F^-$, $Br^-$, $Cl^-$, and $I^-$), the average diameters of the silica nanoparticulates increased to be 43.2, 56.9, 60.0, and 79.9 nm, respectively. And the roughness of q-PDMAEMA films decreased; root-mean-square (rms) values were 3.55 ($F^-$), 1.80 ($Cl^-$), 1.17 ($Br^-$), and 0.88nm ($I^-$), respectively. In addition, the thickness of silica films and q-PDMAEMA films was also influenced by counteranions. The counteranions were found to significantly affect the morphogenesis of silica nanoparticulates on surfaces by interacting with and shaping q-PDMAEMA films differently based on their charge density. In chapter 2, we reported other method for controlling the silica films. The thickness and surface-morphology of biomimetic silica films was controlled by varying the grafting density of PDMAEMA films. The grafting density of the PDMAEMA films was controlled by the surface density of the polymerization initiator. The thickness of sil...