RESUMO
The "smart" polymer poly (N-isopropyl acrylamide), or pNIPAM, has been studied for bioengineering applications. The polymer's abrupt change in hydrophobicity near physiologic temperatures makes it ideal for use as a substrate in many applications, including protein separation and prevention of biofouling. To tether pNIPAM, many techniques such as plasma deposition, have been utilized, but most are expensive and require long equipment calibration or fabrication periods. Recently, a novel method for codepositing this smart polymer with a sol-gel, tetraethyl orthosilicate (TEOS), was developed. In this work, we adapt this technique for applications in mammalian cell attachment/detachment. In addition, we compare the effects of the pNIPAM/TEOS ratio to functionality using surface analysis techniques (XPS and contact angles). We found the optimal ratio to be 0.35 wt % pNIPAM/TEOS. Cell detachment from these substrates indicate that they would be ideal for applications that do not require intact cell sheets, such as biofouling prevention and protein separation, as this technique is a simple and affordable technique for pNIPAM deposition.
Assuntos
Resinas Acrílicas/química , Técnicas de Cultura de Células , Espectroscopia Fotoeletrônica/métodos , Animais , Incrustação Biológica , Bovinos , Adesão Celular , Técnicas de Cultura de Células/métodos , Linhagem Celular , Temperatura Alta , Teste de Materiais , Transição de Fase , Silanos/química , Propriedades de Superfície , Engenharia Tecidual/métodosRESUMO
Highly dispersed gold particles (<2 nm) were synthesized within the pores of mesoporous silica with pore sizes ranging from 2.2 to 6.5 nm and different pore structures (2D-hexagonal, 3D-hexagonal, and cubic). The catalysts were reduced in flowing H2 at 200 degrees C and then used for CO oxidation at temperatures ranging from 25 to 400 degrees C. The objective of this study was to investigate the role of pore size and structure in controlling the thermal sintering of Au nanoparticles. Our study shows that sintering of Au particles is dependent on pore size, pore wall thickness (strength of pores), and pore connectivity. A combination of high-resolution TEM/STEM and SEM was used to measure the particle size distribution and to determine whether the Au particles were located within the pores or had migrated to the external silica surface.
RESUMO
Pores arranged in a two-dimensional hexagonal structure inside spherical mesoporous silica particles help to prevent the thermal sintering of gold nanoparticles compared to straight pores in MCM-41.
