Visible fluorescent sensing of Cu²⁺ ions in urine by reusable chitosan/l-histidine-stabilized silicon nanoparticles...

This study reports a facile approach for the fabrication of chitosan (CS, biopolymer)- and l-histidine (L-His, biomolecule)-stabilized self-assembled silicon nanoparticles (SiNPs) for sensing Cu²⁺ ions. Approached method yielded 3.8 ± 0.04 nm size CS/L-His-SiNPs particles, with high stability against harsh pH and temperature conditions. Besides, CS/L-His-SiNPs highly selective to Copper amongst different metal ions tested (Fe³⁺, Mg²⁺, Al³⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Mn²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Hg²⁺, Ca²⁺, Li²⁺, Po₄^2-, As³⁺, As⁵⁺). As compared to the blank-SiNPs (LOD = 96.49 ± 0.223 μM) and CS-SiNPs (LOD = 33.35 ± 1.004 μM); L-His ligand, enhanced the sensitivity of the CS/L-His-SiNPs toward Cu²⁺ with remarkable LOD value of 55.02 ± 0.42 nM. Applicability of CS/L-His-SiNPs was evaluated by coating CS/L-His-SiNPs on thin layer chromatography (TLC) sheets, CS/L-His-SiNPs-TLC sheets exhibited significant sensing capacity toward Cu²⁺ ions, with a detection range of 4.0-900 μM, making them suitable for on-site analysis of Cu²⁺ ions from both environmental and clinical samples. Finally, Cu²⁺ sensing practicality of CS/L-His-SiNPs-TLC sheets were challenged against real human urine samples. Expressively, CS/L-His-SiNPs-TLC sheets could be regenerated using ethylenediaminetetraacetic acid (EDTA), without losing their photostability, and can be reused further.