Mechanistic study of colorimetric and absorbance sensor developed for trivalent yttrium (Y³⁺) using...

The presence of hazardous, radioactive, and rare earth metal such as yttrium (Y³⁺) in water poses a serious health concern to the public health, thus, exploring novel Y³⁺-binding molecules and colorimetric indicators are desired. Chlortetracycline (CTC)-functionalized silver nanoparticles (AgNPs-CTC) were synthesized, purified by centrifugation and then characterized by UV-vis spectroscopy, XPS, XRD, and HR-TEM. Functionalization of AgNPs with CTC molecules enabled the rapid and sensitive detection of trivalent yttrium ion (Y³⁺). A decrease in the intensity of the original surface plasmon resonance peak at 420 nm was observed within the fraction of a min, with the simultaneous appearance of a new peak at a longer wavelength (540 nm); thus, a novel colorimetric and ratiometric absorbance probe was achieved. The free-O-containing moieties of CTC on the AgNPs surface coordinate with Y³⁺. Thus, CTC molecules led to the bridging of the AgNPs and subsequent aggregation. A good linear relationship (R² = 0.933) in the range of 18 to 243 nM for Y³⁺ was observed, and the limit of detection (LOD) for ratiometric results was approximately 57.7 nM. The AgNPs-CTC sensor exhibited better colorimetric performance in terms of excellent sensitivity, LOD, and rapid formation of the AgNPs-CTC complex towards Y³⁺. The Y³⁺ spiked water samples from different sources and fetal bovine serum suggest that the developed method is practically useful and essentially portable for on-site monitoring. The AgNPs-CTC sensor can be also applied as a common colorimetric indicator for the detection of trace levels of Y³⁺ and lanthanides.