Electrospun nanofibers of porphyrinated polyimide for the ultra-sensitive detection of trace TNT

Nanofibers with distinct luminescent property were facilely fabricated by electrospinning from porphyrinated polyimide and demonstrated as a kind of novel sensory material for trace detection of TNT vapor (10 ppb). Covalently bonding of porphyrin fluorophores into the polyimide main chains reduces the aggregation-caused fluorescence self-quenching of porphyrin and improves the physicochemical stability of the polyimide nanofibers. The large surface area-to-volume ratio and hence good gas accessibility endow the porphyrinated nanofibers with much more remarkable fluorescent quenching behavior toward trace TNT vapor than its spin-coating dense film counterparter. Besides TNT, 2,4-dinitrotoluene (DNT), 2,4,6-trinitrophenol (PA) and nitrobenzene (NB) could also quench the fluorescence of the porphyrinated nanofibers, but the quenching efficiency is much lower than that of TNT. An apparent binding affinity constant of (2.37 ± 0.19) × 107 L/mol was calculated from SPR analysis, confirming that the porphyrinated nanofibers is a promising alternative for TNT detection.