Synthesis of Highly Water-Soluble Fluorescent Conjugated Glycopoly(p-phenylene)s for Lectin and Escherichia coli

• Published in: Biomacromolecules 2006-09, Vol.7 (9), p.2470-2474
• Main Authors: Xue, Cuihua, Jog, Sonali P, Murthy, Pushpalatha, Liu, Haiying
• Format: Article
• Language: English
• Subjects: Applied sciences; Biocompatible Materials - chemistry; Biotechnology - methods; Concanavalin A - chemistry; Escherichia coli - metabolism; Exact sciences and technology; Glucose - chemistry; Kinetics; Lectins - chemistry; Macromolecular Substances; Magnetic Resonance Spectroscopy; Mannose - chemistry; Methylene Chloride - chemistry; Models, Chemical; Organic polymers; Physicochemistry of polymers; Polymers - chemical synthesis; Polymers - chemistry; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Spectrometry, Fluorescence
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm0604404

Two facile, convenient, and versatile synthetic approaches are used to covalently attach carbohydrate residues to conjugated poly(p-phenylene)s (PPPs) for highly water-soluble PPPs bearing α-mannopyranosyl and β-glucopyranosyl pendants (polymers A and B), which highly fluoresce in phosphate buffer (pH 7.0). The post-polymerization functionalization approach is to treat bromo-bearing PPP (polymer 1) with 1-thiolethyl-α-d-mannose tetraacetate or 1-thiol-β-d-glucose tetraacetate in THF solution in the presence of K2CO3 at room temperature through formation of thioether bridges, affording polymer 2a or 2b. The prepolymerization functionalization approach is to polymerize a well-defined sugar-carrying monomer, affording polymer 2a. Polymers 2a and 2b were deacetylated under Zemplén conditions in methanol and methylene chloride containing sodium methoxide, affording polymers A and B, respectively. The multivalent display of carbohydrates on the fluorescent conjugated glycopolymer overcomes the characteristic low binding affinity of the individual carbohydrates to their receptor proteins. Titration of concanavalin A (Con A) to α-mannose-bearing polymer A resulted in significant fluorescent quenching of the polymer with Stern−Volmer quenching constant of 4.5 × 107. Incubation of polymer A with Escherichia coli (E. coli) lead to formation of fluorescently stained bacterial clusters. β-Glucose-bearing polymer B displayed no response to Con A and E. coli.