Multivalent interaction between boronic acids immobilized on Quartz Crystal Microbalance (QCM) sensor surface and the carbohydrates modified Au -nanoparticle (AuNP) has been demonstrated for the development of a sensitive carbohydrate biosensor. Briefly, a boronic acidcontaining polymer (boropolymer) as multivalent carbohydrate receptor was oriented immobilized on the cysteamine coated electrode through isourea bond formation. Carbohydrates were conjugated to AuNPs to generate a multivalent carbohydrates moiety to amplify the response signal. Thus, the binding of the carbohydrate conjugated AuNPs to the boropolymer surface are multivalent which could simultaneously increase the binding affinity and specificity. We systematically studied the binding between five carbohydrate conjugated AuNPs and the boropolymer. Our studies show that the associate constant (K a ) was in the order of fucose < glucose < mannose < galactose < maltose. A linear response in the range from 23 µM to 3.83 mM was observed for mannose conjugated AuNPs and the boropolymer recognition elements, with the lower detection limit of 1.5 µM for the carbohydrate analytes. Furthermore, the multivalent binding between carbohydrates and boronic acids are reversible and allow the regeneration of boropolymer surface by using 1M acetic acid so as to sequentially capture and release the carbohydrate analytes.

No abstract

An oriented glyco-capturing macroligand was synthesized by site-specific immobilization of an O-cyanate chain-end-functionalized boronic acid containing polymer (boropolymer) onto an amine surface. The O-cyanate chain-end-functionalized boropolymer was synthesized by arylamine-initiated cyanoxyl-mediated free-radical polymerization in a one-pot fashion. The chain-end O-cyanate was confirmed by (13)C NMR spectroscopy. The specific carbohydrate-binding capacity of the boropolymer was evaluated by an alizarin red S assay. Oriented and covalent immobilization of the O-cyanate chain-end-functionalized boropolymer onto the amine-modified solid surfaces and its specific glyco-capturing capacity were confirmed by the quartz crystal microbalance (QCM) and atomic force microscopy (AFM) techniques. The oriented multivalent glyco-capturing ligand can be used for efficient carbohydrate and glycoconjugate purification and identification, and thus is expected to constitute a core strategy of glycomics and glycoproteomics and carbohydrate-sensing applications.

No abstract