This review highlights recent advances towards non-invasive and continuous glucose monitoring devices, with a particular focus placed on monitoring glucose concentrations in alternative physiological fluids to blood.

Owed to their reversible diol-binding ability, phenylboronic acid (BA) derivatives have gained considerable interest for the development of saccharide sensors and drug delivery systems. In particular, BA-containing polymers have been used for the realization of sugar-responsive layer-by-layer (LbL) films. Herein, a LbL system based on cationic BA-homopolymers (PBA) is presented, and its subsequent sugar-induced disassembly is described. The BA-linear polymers (PBA) were intercalated with poly(vinylsulfonic acid, sodium salt) to form (PBA/PVS)_n film assemblies. Different orientations of the boronic acid substituent (ortho-, meta-, and para-) in the PBA polymer were investigated for their influence on the LbL assembly. The rate of disassembly in the presence of glucose or fructose was analyzed by UV–vis spectroscopy. Additionally, the PVS component was replaced with an anionic fluorophore, pyranine (PYR), which allowed the assembly and disassembly to be monitored by fluorescence.

Since the initial breakthroughs in the 1960s and 1970s that led to the development of the glucose biosensor, the oxygen electrode, ion-selective electrodes, and electrochemical/optochemical diagnostic devices, the vision of very reliable, affordable chemical sensors and bio-sensors capable of functioning autonomously for long periods of time (years) remains unrealized.