Magnetic nanoparticles with dendrimer-assisted boronate avidity for the selective enrichment of trace glycoproteins

Boronic acid-functionalized materials have been the subject of increasing attention in recent years due to their capability in the facile selective extraction of glycoproteins. However, boronic acids are associated with weak binding affinity, and it is thereby difficult for boronate affinity materials to extract glycoproteins of low concentration. Here we present for the first time a boronate avidity material, dendrimeric boronic acid-functionalized magnetic nanoparticles, with significantly enhanced binding strength towards glycoproteins. Due to the dendrimer-assisted multivalent synergistic binding, the boronate avidity material exhibited dissociation constants of 10(-5) to 10(-6) M towards glycoproteins, which are 3-4 orders of magnitude higher than the affinities of single boronic acid binding. Such an avidity enabled the selective extraction of trace glycoproteins; an extractable concentration as low as 2 x 10(-14) M was demonstrated. Meanwhile, the boronate avidity material was tolerant of the interference of abundant competing sugars. Moreover, the dendrimeric boronic acid-functionalized magnetic nanoparticles exhibited two additional advantages: high binding capacity and fast binding/desorption speed. Due to these favourable features, the selective enrichment of trace glycoproteins by the boronate avidity material became not only possible but also efficient. Efficient enrichment of trace glycoproteins from human saliva was demonstrated. The dendrimer-assisted synergistic binding strategy is also applicable to other types of boronic acid-functionalized materials and other types of functionalized materials.