Rational Design of Optical Single-Walled Carbon Nanotube-Based Nanosensors with Biological Recognition Elements.

Single-walled carbon nanotubes (SWCNT) can serve as powerful transducers for optical nanobiosensors. As near-infrared (NIR) fluorophores, they are used for a wide variety of biological sensing and imaging applications in vitro and in vivo. Rational biosensor design relies on the use of biological recognition elements to detect the sensor's target. In rationally designing SWCNT nanobiosensors, the nanotubes are functionalized with a biological recognition motif, whose binding event induces a modulation in SWCNT fluorescence, which can be measured with NIR spectroscopy in a well plate or cuvette, in cells, or through tissue of live animals. In this review, the sensor design strategies and functional outcomes of rationally-designed optical SWCNT sensors are assessed that employ biological recognition elements for analyte specificity. The biomolecular recognition elements are divided into categories of proteins, peptides, or oligonucleotides, and assessed functionalization schemes, highlighting advances made in the fields of biomedical sensing and imaging through rational design. Finally, a perspective is offered on remaining challenges and future directions for the field of SWCNT optical sensor engineering and hurdles for translation to the clinic.