Fundamental research on functionalization of diatomite using DNA-coated single-walled carbon nanotubes

Diatomite is a structural material with pores several tens of nanometers in size on its surface. It is used as a base material for adsorbents, carriers, and catalysts. Carbon nanotubes are materials with excellent electrical and thermal conductivities, and their application as novel carbon materials in new growth fields, including biosensors, has been widely studied. In this study, single-walled carbon nanotubes (SWNTs) by HiPco method were adsorbed onto diatomite with alkali, a natural porous silica, to fabricate light-responsive device floats in water. SWNT-diatomite complexes were prepared by adsorbing SWNTs coated with single-stranded DNA onto silanized diatomite. Near-infrared photoluminescence measurements showed that the prepared complexes exhibited strong emission intensity at excitation wavelength of 650 nm and emission wavelength of 1100 nm. Microscopic observation confirmed that the stirred diatomite remained suspended in water for 30 min. These complexes demonstrated the potential for the development of photoresponsive devices for water purification and biosensing.