Fluorescent nonconjugated zwitterionic polymer dot: hydrothermal synthesis and application towards the nano-molar sensing of 2, 4, 6-trinitrophenol

Abstract

Developing nonconjugated polymer dot-based sensors with high quantum yield for a targeted application is a challenging research field. Herein we are reporting the synthesis of a zwitterionic polymer dots (PD PAMAM 2.5, average diameter 12 nm), which contains a poly(aminoamide) core and amine, acid groups on the surface. The molecular structure and functionalities of the polymer dot was carefully established by a number of spectroscopic techniques which include, NMR, FTIR, XPS etc. The polymer dot reveals greenish blue/aqua emission (λmax = 470 nm) with a quantum yield of 28%. Mechanism for the synthesis of polymer dots with respect to its structure and fluorescence property is examined by a combination techniques including NMR, zeta potential and fluorescence spectrometry. The application of the fluorescent polymer dot for selective detection of 2, 4, 6-trinitrophenol is studied in detail. The limit of detection is determined as 0.77 nM, which is among the best in context of the current state of art. Further, application of the polymer dot in real life applications is demonstrated using real life waste water samples and a paper based strip-test method.