Nitric Oxide Detection Using a Corona Phase Molecular Recognition Site on Chiral Single-Walled Carbon Nanotubes

Abstract

Semiconducting single-walled carbon nanotubes (s-SWCNT) are structures that fluoresce in the near-infrared region. By coating SWCNT surfaces with polymeric materials such as single-chain DNA, changes in fluorescence emission occur in the presence of reagents. In this way, polymer-coated SWCNT structures allow them to be used as optical sensors for single molecule detection. Especially today, the inadequacy of the methods used in the detection of cellular molecules makes the early diagnosis of diseases such as cancer difficult at the singlemolecule level. In this study, the detection of nitric oxide (NO) signals, which are a marker of cancer, was carried out at the singlemolecule level. In this context, a sensor structure was formed by coating the 7,6-chiral s-SWCNT surface with ssDNA with different oligonucleotide lengths (AT). The sensor structure was characterized by using UV−vis spectroscopy and Raman spectroscopy microscopy. After formation of the sensor structure, a selectivity library was created using various molecules. As a result of the coating of the SWCNT (7,6) surface with DNA corona phase formation, Raman peaks at 195 and 276 cm −1 were observed to shift to the right. Additionally, the selectivity library results showed that the (AT)30 sequence can be used in NO detection. As a result of the studies using SWCNT (7.6)-(AT)30, the limit of detection (LOD) and limit of determination (LOQ) values of the sensor against NO were found to be 1.24 and 4.13 μM, respectively.

Monitoring Enzyme Activity Using Near-Infrared Fluorescent Single-Walled Carbon Nanotubes

“…In light of these considerations, the significance of luminescent probes operating in the near-infrared (NIR) region becomes evident. These probes offer real-time and spatiotemporal information, and their utility is particularly notable because biological samples are mostly transparent in the NIR region. − In pursuit of this objective, NIR luminescent single-walled carbon nanotubes (SWCNTs) are advantageous due to their intrinsic physicochemical and optical properties. ,− These include the high surface area and the ease of surface functionalization with molecules of choice that facilitate interaction with a large number of analytes, enabling high-throughput readouts. − Moreover, SWCNTs exhibit remarkable photo and chemical stability, rendering them a compelling choice as sensors for monitoring essential biomarkers, including proteins, − oncometabolites, pathogens, , various small molecules, − hormones, ,, volatiles, , lipids, ,, sugars, − neurotransmitters, ,,− microRNA, , metal ions, lysosomal pH, and enzymatic activity and inhibition. −…”