Spectroscopy analysis of the alignment of nanoassemblies of DNA-wrapped carbon nanotubes in stretched gelatin film

Abstract

We present the polarized Raman studies and light absorption study of nanoassemblies of DNA-wrapped single-walled carbon nanotubes (SWNTs) incorporated into the gelatin film. Nanoassemblies are formed in aqueous suspension with SWNTs:DNA by positively charged 5,10,15,20-tetrakis-(N-methyl-4-pyridyl) porphyrin (TMPyP4). The gelatin film with embedded nanoassemblies was exposed to a mechanical stretching to about 300% tensile strain for making an alignment along a chosen direction. The analysis of the absorption spectra taken along and normal to the stretching direction revealed the strong polarized dependence. The polarized Raman spectra of the stretched gelatin film showed the angular dependence of the integrated intensity of tangential mode of SWNTs that allowed to estimate the alignment degree. It showed that about 60% of the SWNT nanoassemblies are aligned in the range of ± 15° to the direction of the stretching. The addition of the porphyrin derivative does not impede the orientation of the SWNTs:DNA nanohybrids along the stretching direction. The performed studies of embedded SWNTs:DNA:TMPyP4 nanoassemblies in the flexible gelatin film are intended to show the simple method for obtaining the controlled ordered biocompatible nanotube networks functionalized by the porphyrin derivatives inside a polymer matrix.