A universal strategy for direct immobilization of intact bioactivity-conserved carbohydrates on gold nanoparticles

Abstract

Carbohydrate-functioned gold nanoparticles have been highlighted for sensing complicated carbohydrates but their performance is far from ideal due to the lack of bioaffinity-conserved ways to function the particles with intact carbohydrates. Herein, we present an innovative method to directly immobilize intact carbohydrates on gold nanoparticles with cyanuric chloride as a linker. Both small and large carbohydrates were successfully immobilized on GNPs at a surface coverage of 43.5% (tested by mannose). Pre-treatment of the carbohydrates was avoided and no loss of their recognition ability towards lectins was observed after immobilization, even in the case of monosaccharides. The mechanism was attributed to the three σ-linking bonds which are rotatable and spaced at 120°, enabling the immobilized carbohydrates to find their best spatial position to favour their recognition. The method can minimize immobilizing chemical reactions and ease the manipulation by simply controlling the reaction temperature. It is cost-effective and extendable to the immobilization of other hydroxyl compounds and amines as well.