An in situ study of metal complexation by an immobilized synthetic biopolymer using tapping mode liquid cell atomic force microscopy.
Near-field scanning optical microscopy and tapping mode, liquid cell atomic force microscopy were used to study the conformational changes in simple short-chain silica-immobilized biopolymer, poly(L-cysteine) (PLCys), as the polymer was exposed to reducing, metal-rich, and acidic environments, respectively, to simulate on-line metal preconcentration. In a reducing environment (0.01 M dithiothreitol in pH 7.0 ammonium acetate buffer), the PLCys features resembled islands on the surface of the glass, 36 +/- 7 nm in height and 251 +/- 60 nm in diameter. Upon exposure to metal (Cd2+ buffered at pH 7.0), the PLCys islands broke up into smaller metal binding clusters whose features were lower in height, 22 +/- 5 nm, and diameter, 213 +/- 53 nm. Exposure to 0.01 M HCl used for metal stripping resulted in protonation of the polymer chains and further reduction in the polymer height to 12 +/- 5 nm. These changes in molecular structure have given new insight into the mechanisms involved to achieve strong binding as well as rapid, quantitative release of bound metals to flexible short-chain synthetic biopolymers.
Miller
T C
TC
Department of Chemistry and Biochemistry, University of Texas at Austin, 78712, USA.
Kwak
E S
ES
Howard
M E
ME
Vanden Bout
D A
DA
Holcombe
J A
JA
D001704:Biopolymers / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D010455:Peptides / Q000737:chemistry; D013050:Spectrometry, Fluorescence
D001704:Biopolymers; D008670:Metals; D010455:Peptides; C057713:polycysteine