Herein, a novel ‘‘turn on’’ ion-imprinted chemosensor for highly sensitive and selective detection of Al3+ ions in
complex matrices has been developed. The method was based on using chitosan (CHIT) biopolymer/magnetite
nanoparticles (MGNPs) functionalized with 8-hydroxyquinoline sulfonic acid (8-HQS) in the presence of Al3+ ions
to synthesize a magnetite ion non-imprinted biopolymer (MGINIBP) chemosensor. This newly developed
chemosensor was synthesized via polymerization of CHIT with [3-(2,3-epoxypropoxy)-propyl]trimethoxysilane
[EPPTMS] in the presence of magnetite nanoparticles, 8-HQS, and an Al3+ ion template. The template was then
removed from the sensor using 0.5 M NaF to form new recognition sites for Al3+. The newly developed
chemosensor was termed as a magnetite ion-imprinted biopolymer (MGIIBP). Exposure of Al3+ ions to the
developed system embedded with 8-HQS resulted in the formation of a fluorescent polymer, and
emission maximum was obtained at 500 nm after excitation at 365 nm. Furthermore, with the increasing
Al3+ ion concentration, the fluorescence intensity increases within the range 0.081–9.0  108 M with a
limit of detection (LOD) of 0.027  108 M. In addition, the synthesized chemosensor was characterized
by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and Fourier-transform infrared
spectroscopy (FTIR). The proposed MGIIBP sensor was successfully applied to the determination of Al3+
ions in water and human serum samples as model examples of complex natural matrix media.