Bioinspired synthesis of poly(phenylboronic acid) microgels with high glucose selectivity at physiological pH
A highly selective response to glucose is possible by using a poly(phenylboronic acid) microgel prepared by a rational design. Such a microgel is made of a commercial 4-vinylphenylboronic acid crosslinked with N,N′-bis(propene)perylene-3,4,9,10-tetracarboxyldiimide. The introduction of a suitable amount of perylene bisimides into the poly(phenylboronic acid) network can make the newly developed microgels responsive with high selectivity to glucose over a clinically relevant concentration range of 0.0–30.0 mM at a physiological pH of 7.4. Unlike poly(phenylboronic acid) gels reported in previous reports that swell but show poor glucose selectivity, or shrink upon adding glucose, the proposed microgels swell and the swelling ratio is much larger than that upon adding other common monosaccharides (natural stereoisomers of glucose, e.g., fructose, galactose and mannose). The responsive volume phase transitions of the microgels give excellent fits to a 1:1 binding model, to estimate an association constant of 212 M−1 for glucose binding, which is remarkably larger than those of 78, 42 and 52 M−1 respectively, for fructose, galactose and mannose binding. The proposed microgels also feature a class of built-in signalling systems in the form of highly selective glucose-dependent fluorescence emission. The highly selective glucose-response of the microgels suggests the potential for development into sensors for detection of glucose in serums of fasting bloods and even non-fasting bloods (as models of complex bio-systems).