Templating colloidal sieves for tuning nanotube surface interactions and optical sensor responses

Area of Science:

• Nanotechnology
• Materials Science
• Biomedical Engineering

Background:

• Single-walled carbon nanotubes (SWCNTs) are promising for optical sensing due to their fluorescence properties.
• Surfactants provide a cost-effective method for suspending SWCNTs, improving quantum yields.
• Current surfactant-based SWCNT sensors lack the necessary selectivity for precise optical sensing applications.

Purpose of the Study:

• To develop a new method for enhancing the selectivity of optical SWCNT sensors.
• To investigate the use of colloidal templating via sodium cholate concentrations for sensor surface area modulation.
• To compare the performance of sodium cholate-suspended SWCNT sensors with DNA-SWCNT sensors.

Main Methods:

• SWCNTs were suspended in various concentrations of sodium cholate to create colloidal suspensions.
• The optical sensor performance was evaluated by measuring responses to a panel of bioanalytes, including neurotransmitters, amino acids, and sugars.
• Sensor selectivity was assessed by analyzing wavelength shifts and intensity changes in SWCNT fluorescence.

Main Results:

• All sodium cholate concentrations showed an intensity response to dopamine and serotonin.
• Selective red-shifting responses of 14.1 nm and 10.3 nm to serotonin were observed for SWCNTs suspended in 1.5 mM and 0.5 mM sodium cholate, respectively.
• The colloidal templating method demonstrated superior selectivity compared to DNA-SWCNT sensors.

Conclusions:

• Sub-critical colloidal suspensions of SWCNTs offer a tunable approach for enhancing sensor selectivity.
• Adsorption-based tuning of the SWCNT surface via colloidal suspensions provides a viable strategy for developing highly selective optical sensors.
• This method surpasses the selectivity of existing DNA-SWCNT sensors for specific bioanalyte detection.