Antibody-conjugated species-sorted single-walled carbon nanotubes for multiplexed cytokine sensing

Single-walled carbon nanotubes (SWCNT) are versatile building blocks for optical sensors. Their near infrared photoluminescent emission is determined by their chiral structure. Commercially available SWCNT are polydisperse, leading to spectral congestion and no ability single analyte sensing. Aqueous two-phase extraction (ATPE) is a technique to sort SWCNT structures for improved nanosensor performance and multiplexed sensing. To date, ATPE has not been demonstrated with bioconjugate-compatible surface chemistries. Here, we demonstrate improved and multiplexed cytokine sensing by ATPE sorting SWCNT species with amine-functionalized ssDNA. We show that this approach enables effective chirality sorting and direct antibody conjugations. We used sorted, functionalized SWCNT to simultaneously and specifically detect the inflammatory cytokines IL-12 and IL-6 with high sensitivity and selectivity, and improved robustness compared to unsorted SWCNT. We anticipate that such sensitive, multiplexed will be useful for implantable and bedside diagnostics of inflammatory processes while serving as a model for sensing other complex biological processes.