Liquid-crystal droplets functionalized with a non-enzymatic moiety for glucose sensing

3-Aminophenyl boronic acid (APBA)-decorated 4-cyano-4′-pentylbiphenyl (5CB) microdroplets were utilized for glucose detection with high specificity and sensitivity. APBA decoration was performed by firstly coating poly(acrylic acid) (PAA) on the 5CB droplet with amphiphilic poly(4-cyanobiphenyl-4′-undecylacrylate-b-acrylicacid) (LCP-b-PAA) and performing covalent bonding of APBA to the PAA chains by EDC coupling between the acrylic groups of PAA and the amine groups of APBA. The binding events between APBA and glucose were translated by configurational change (from radial to bipolar) of the 5CB droplets, observed under a polarized optical microscope with crossed polarizers. The liquid crystal (LC) droplet-based non-enzymatic (NE) biosensor for glucose detection exhibited high sensitivity (detection limit of 0.05 mM) even in complex serum sample, high selectivity against cholesterol, uric acid, and acetaminophen, and good stability for 30 d. This NE-based glucose LC biosensor is cost-effective and highly stable compared to enzyme-based LC glucose biosensors and thus, could replace such enzyme-based biosensors.