Fluorescent Guar Gum-g-Terpolymer via In Situ Acrylamido-Acid Fluorophore-Monomer in Cell Imaging, Pb(II) Sensor, and Security Ink.

Abstract

The nonconventional purely aliphatic scalable and reusable fluorescent guar gum (GRGM)-grafted-acrylic acid-co-3-(N-isopropylacrylamido)propanoic acid (NIPAPA)-co-N-isopropylacrylamide (GRGM-grafted-1, i.e., 2), was synthesized via grafting of the optimum amount of GRGM and N-H functionalized in situ protrusion of acrylamido-acid fluorophore-monomer, i.e., NIPAPA, in multi C-C/N-C/O-C coupled solution polymerization of two non-emissive monomers in water. The intrinsically fluorescent noncytotoxic 2 envisaged the excellent potentials in sensing and removal of Pb(II), security ink, logic function, and imaging of both cancer and normal cells. The emission intensities of 2 elevated in concentrated solutions and solid state because of concentration-enhanced emission and aggregation-induced enhanced emission (AIEE) characteristics of 2. Additionally, the emission efficiency of 2 elevated considerably with increasing GRGM contents and temperatures. The structure of 2, in situ attached fluorophore-monomer, AIEE, cell-imaging ability, and the superadsorption mechanism were studied employing 1H/13C NMR, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, atomic absorption spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, dynamic light scattering, high-resolution transmission electron microscopy, fluorescence imaging, and fluorescence lifetime, along with measuring isotherms, kinetics, and thermodynamic parameters. The location, geometries, and electronic-structures of fluorophore, along with absorption and emission properties, of 2 were explored via density functional theory (DFT), time-dependent DFT, and natural transition orbital analyses. In solution, cyan light-emitting 2 envisaged an average 1.22 ns lifetime in CHCl3. The limit of detection and the maximum adsorption capacity were 2.94 × 10-7 M and 1100.25 mg g-1 at pH 7.0, 303 K, and 1000 ppm, respectively.