An optical fiber biosensor based on a modified single sol gel film consisting of urease and chlorophenol red (CPR) was employed to detect heavy metal ions in aqueous samples. The modification relies on addition of poly(vinyl alcohol) (PVA) into sol-gel matrix, in order to increase the function of urease. The biosensing element on a sol-gel film has been placed inside the specially designed flow-cell for the flow system measurements. In the presence of a constant urease, a color change of the CPR and the measured reflected signal intensity at wavelength 580 nm could be related to the heavy metal ions concentration in the sample solutions. The performance of optical biosensor in the flow system has been optimized. A linear calibration curve of heavy metals against the percentage inhibition of urease was obtained at mu g/L level for heavy metal ions tested [Hg(II), Ag(I), Pb(II), Cu(II) and Cd(II)]. The biosensing element was regenerated using EDTA. Real sample analysis using the biosensor revealed that it was promising for water analysis of trace levels of heavy metal ions.
Full text available here and research gate.