title: Highly selective preconcentration of ultra-trace cadmium by yeast surface engineering.
abstract: The potential of selective cell-sorption for separation/preconcentration of ultra-trace heavy metals was exploited by surface engineering of Saccharomyces cerevisiae cells. The general idea is to display the cadmium-binding peptide on the cell surface in order to enhance the covalent interaction between cadmium and the yeast cells. By immobilizing the surface-engineered yeast cells onto cytopore(®) microcarrier beads for cadmium adsorption, we demonstrated that with respect to the native yeast 600-fold and 25-1000-fold improvements were observed respectively for the tolerance of ionic strength and the tolerant capability toward various metal cations after surface engineering. Based on these observations, a novel procedure for selective cadmium preconcentration was developed with detection by graphite furnace atomic absorption spectrometry (GFAAS), employing the engineered S. cerevisiae cell-loaded cytopore(®) beads as a renewable sorption medium incorporated into a sequential injection lab-on-valve system. The cadmium retained on the yeast cell surface was eluted with a small amount of nitric acid and quantified with GFAAS. Within a range of 5-100 ng L(-1) and a sample volume of 1 mL, an enrichment factor of 30 was achieved along with a detection limit of 1.1 ng L(-1), a sampling frequency of 20 h(-1) and a precision of 3.3% RSD at 50 ng L(-1). The procedure was validated by analyzing cadmium in certified reference materials and a series of environmental water samples.
authors: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Shenyang, China.
authors: Ting
authors: T
authors: Yang
authors: Xiao-Xing
authors: XX
authors: Zhang
authors: Ming-Li
authors: ML
authors: Chen
authors: Jian-Hua
authors: JH
authors: Wang
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000032:analysis* / Q000737:chemistry; D018914:Cells, Immobilized; D012441:Saccharomyces cerevisiae; D013054:Spectrophotometry, Atomic / Q000379:methods*; D013499:Surface Properties; D014131:Trace Elements / Q000032:analysis* / Q000737:chemistry
chemical_list: D014131:Trace Elements; D002104:Cadmium