Binding of Ricinus communis agglutinin to a galactose-carrying polymer brush on a colloidal gold monolayer.
A polymer with many pendent galactose residues was prepared by atom-transfer radical polymerization (ATRP) of galactose-carrying vinyl monomer, 2-lactobionamidoethyl methacrylate (LAMA), with a disulfide-carrying ATRP initiator, 2-(2'-bromoisobutyroyl)ethyl disulfide (DT-Br). The galactose-carrying polymer obtained (DT-PLAMA) was accumulated as a polymer brush via Au-S bond on a colloidal gold monolayer deposited on a cover glass. For comparison, a disulfide which carried one galactose residue at both ends (2-lactobionamidoethyl disulfide, Cys-Lac) was accumulated as a self-assembled monolayer (SAM) on the colloidal gold monolayer, too. The association and dissociation processes of galactose residues on the colloidal gold with a lectin, Ricinus communis agglutinin (RCA(120)), were observed by the increase and decrease in absorbance at 550nm corresponding to localized surface plasmon resonance (LSPR) phenomena. The Cys-Lac SAM-carrying glass chip showed a strong non-specific adsorption of the lectin, whereas the DT-PLAMA brush-carrying one reversibly associated with the lectin, indicating reusability of the latter device. The apparent association constant of the lectin with the galactose residues in the DT-PLAMA brush was much larger than the association constant for free galactose, and the detection limit of RCA(120) by the glycopolymer brush-modified device was satisfactorily low. Furthermore, a microscopic observation clearly indicated that the DT-PLAMA brush could reversibly associate with a HepG2 cell having galactose receptors, though these processes could not be observed spectrophotometrically due to a gigantic size of the cell.
Mizukami
Kazuya
K
Department of Applied Chemistry, Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan.
Takakura
Hajime
H
Matsunaga
Takayuki
T
Kitano
Hiromi
H
D000327:Adsorption; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D005690:Galactose / Q000737:chemistry* / Q000378:metabolism*; D017979:Gold Colloid / Q000737:chemistry* / Q000378:metabolism; D037102:Lectins / Q000737:chemistry; D008113:Liver Neoplasms / Q000378:metabolism; D008689:Methacrylates / Q000737:chemistry; D037121:Plant Lectins / Q000737:chemistry / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D017979:Gold Colloid; D037102:Lectins; D008689:Methacrylates; D037121:Plant Lectins; D011108:Polymers; C017707:Ricinus communis agglutinin-1; D005690:Galactose