Using a fluorescence quenching method to detect DNA adsorption onto single-walled carbon nanotube surfaces

Abstract

Surface modification of single-walled carbon nanotubes (SWNTs) with DNA molecules has attracted much attention in recent years to increase SWNT solubility and make various SWNT-based nanobiodevices. Therefore, there is a critical need to quantify the interaction between DNA molecules and SWNT surfaces, particularly the intermediate structures during DNA adsorption. In this study, we demonstrate the ability to detect the adsorption of DNA oligomers on SWNT surfaces by fluorescence spectroscopy. Fluorescein-labelled, 30 mer, thymine oligonucleotides (F-T30) were employed as a fluorescent probe to study the interaction of DNA with SWNTs. A clear quenching effect was observed when F-T30 was adsorbed onto SWNT surfaces. Using this method, the amount of DNA adsorbed onto the SWNT surfaces was measured under different sonication conditions to correlate absorption efficiency with sonication strength and duration. When a bath-type sonicator was used, mild adsorption of F-T30 on SWNT surfaces was observed. Furthermore, a two-step adsorption was observed in this condition. In contrast, we observed rapid adsorption of F-T30 to SWNT surfaces at the higher sonication amplitude (60% maximal) using a probe-type sonicator, while only slight adsorption of DNA molecules was observed at the lower amplitude (20% maximal). Our data revealed that the quenching effect can be used to evaluate DNA adsorption onto SWNT surfaces. In addition, atomic force microscopy (AFM) and photoacoustic spectroscopy (PAS) were conducted to provide complementary information on the DNA-SWNT nanoconjugates.

Corona Exchange Dynamics on Carbon Nanotubes by Multiplexed Fluorescence Monitoring

“…This assay exploits the quenching of fluorophores when in close proximity to the SWCNT surface to monitor ligand binding and unbinding events . While prior literature has similarly harnessed fluorophore quenching by SWCNTs to study the ssDNA-to-SWCNT binding process, ,, far less is known regarding how preadsorbed ssDNA and biologically native proteins exchange on the SWCNTs. To our knowledge, this method is unique in enabling real-time monitoring of SWCNT surface exchange between ssDNA and proteins, tracing the fate of all biomolecules involved in the binding exchange.…”

Quantitative Detection of the Disappearance of the Antioxidant Ability of Catechin by Near-Infrared Absorption and Near-Infrared Photoluminescence Spectra of Single-Walled Carbon Nanotubes

“…Near-infrared (NIR) absorption spectra of single-walled carbon nanotubes (SWNTs) are sensitive against structural and physicochemical changes of SWNTs. − For example, it is known that NIR absorbance is weakened when SWNTs are oxidized . NIR photoluminescence (PL) from SWNTs by irradiation with visible lights is also fluctuated according to structures of SWNTs and changes of sample conditions. − These unique optical responses of SWNTs can therefore be applied to various biological applications. − Especially, nanobiosensing that uses SWNT unique optical properties is one of the promising approaches, and attachment of biomolecules onto DNA–SWNTs to functionalize the hybrids has been intensively studied by many research groups. − …”

Corona exchange dynamics on carbon nanotubes by multiplexed fluorescence monitoring

“…This assay exploits the quenching of fluorophores when in close proximity to the SWCNT surface to monitor ligand binding and unbinding events. 26 While prior literature has similarly harnessed fluorophore quenching by SWCNTs to study the ssDNA-to-SWCNT binding process, 8,18,27 far less is known regarding how pre-adsorbed ssDNA and biologically native proteins exchange on the SWCNTs. To our knowledge, this method is unique in enabling real-time monitoring of SWCNT surface exchange between ssDNA and proteins, tracing the fate of all biomolecules involved in the binding exchange.…”