Enhancement of Photoluminescence from Semiconducting Nanotubes in Aqueous Suspensions due to Cysteine and Dithiothreitol Doping: Influence of the Sonication Treatment.

The influence of tip sonication duration on the spectral characteristics of carbon single-walled nanotubes (SWNTs) in aqueous suspension with single-stranded DNA (ssDNA) has been studied by NIR luminescence, NIR absorption, and Raman spectroscopy. It was revealed that prolongation of sonication leads to weakening of the SWNT polymer coverage and appearance of additional defects on the nanotube surface. Prolongation of the tip sonication treatment of SWNT/ssDNA from 30 to 90 min leads to the increase of the number of individual nanotubes in the aqueous suspension, but it significantly decreases the photoluminescence (PL) from semiconducting SWNTs because more defects are formed on the nanotube surface.

Probing the Influence of Amino Acids on Photoluminescence from Carbon Nanotubes Suspended with DNA.

The quantitative analysis of amino acid levels in the human organism is required for the early clinical diagnosis of a variety of diseases. In this work the influence of 13 amino acid doping on the photoluminescence (PL) from the semiconducting single-walled carbon nanotubes (SWNTs) suspended with single-stranded DNA (ssDNA) in water has been studied. Amino acid doping leads to the PL enhancement and the strongest increase was found after cysteine doping of the nanotube suspension while addition of other amino acids yielded the significantly smaller effect.