Near Infrared Fluorescent Nanosensor for Iron

Disclosed herein is a near infrared (nIR) fluorescent nanosensor for detecting iron species, comprising a complexation of individual single-walled carbon nanotubes (SWNT), wherein the SWNT are nIR fluorescent, and a water-soluble polymer. The nIR fluorescent nanosensors offer a specific and sensitive sensing platform for quantification and speciation of dissolved or bioavailable Fe(II) and FeIII) in both their free ionic and chelated forms, and have been demonstrated for use in detection of iron via root uptake in planta, as well as in the detection of "free" or non-transferrin bound iron (NTBI) in human serum.