Guanine Quantum Defects in Carbon Nanotubes for Biosensing

Area of Science:

• Nanotechnology
• Materials Science
• Biochemistry

Background:

• Fluorescent single-wall carbon nanotubes (SWCNTs) are utilized as nanoscale biosensors.
• Noncovalent functionalization with DNA provides selectivity.
• Covalent functionalization via guanine quantum defects (g-defects) has recently emerged.

Purpose of the Study:

• To create g-defects in (GT)10-coated SWCNTs (G d -SWCNTs).
• To investigate the impact of g-defects on molecular sensing properties.
• To explore changes in physiochemical properties and optical sensing performance.

Main Methods:

• Covalent functionalization of SWCNTs with guanine bases to form g-defects.
• Varied defect densities in (GT)10-coated SWCNTs.
• Characterization of fluorescence emission shifts, Stokes shift, and dopamine/riboflavin sensing.

Main Results:

• G-defect creation shifted fluorescence emission by 55 nm to 1049 nm.
• Stokes shift increased linearly with defect density by up to 27 nm.
• G d -SWCNTs showed >70% fluorescence increase for dopamine and 93% decrease for riboflavin.
• Cellular uptake of G d -SWCNTs decreased.

Conclusions:

• G-defects significantly alter SWCNT physiochemical and optical properties.
• G d -SWCNTs demonstrate enhanced sensitivity and selectivity for molecular sensing.
• These modified SWCNTs offer a versatile platform for advanced optical biosensors.