Size-Exclusive Nanosensor for Quantitative Analysis of Fullerene C<sub>60</sub>
Abstract
This paper presents the first development of a mass-sensitive nanosensor for the isolation and quantitative analyses of engineered fullerene (C₆₀) nanoparticles, while excluding mixtures of structurally similar fullerenes. Amino-modified beta-cyclodextrin (β-CD-NH₂) was synthesized and confirmed by ¹HNMR as the host molecule to isolate the desired fullerene C₆₀. This was subsequently assembled onto the surfaces of gold-coated quartz crystal microbalance (QCM) electrodes using N-dicyclohexylcarbodiimide/N-hydroxysuccinimide (DCC/NHS) surface immobilization chemistry to create a selective molecular configuration described as (Au)-S-(CH₂)²-CONH-beta-CD sensor. The mass change on the sensor configuration on the QCM was monitored for selective quantitative analysis of fullerene C₆₀ from a C₆₀/C₇₀ mixture and soil samples. About ~10¹⁴-10¹⁶ C₆₀ particles/cm² were successfully quantified by QCM measurements. Continuous spike of 200 μL of 0.14 mg C₆₀ /mL produced changes in frequency (-Δf) that varied exponentially with concentration. FESEM and time-of-flight secondary-ion mass spectrometry confirmed the validity of sensor surface chemistry before and after exposure to fullerene C₆₀. The utility of this sensor for spiked real-world soil samples has been demonstrated. Comparable sensitivity was obtained using both the soil and purified toluene samples. This work demonstrates that the sensor has potential application in complex environmental matrices.