Recent Progress and Perspectives on Non-Invasive Glucose Sensors

Self-monitoring of blood glucose forms an important part of the management of diabetes and the prevention of hyperglycaemia and hypoglycaemia. Current glucose monitoring methods either use needle-prick enzymatic glucose-meters or subcutaneous continuous glucose sensors (CGM) and thus, non-invasive glucose measurements could greatly improve the self-management of diabetes. A wide range of non-invasive sensing techniques have been reported, though achieving a level of precision comparable to invasive meters remains a challenge. Optical sensors, which utilise the interactions between glucose and light, offer the potential for non-invasive continuous sensing, allowing real-time monitoring of glucose levels, and a range of different optical sensing technologies have been proposed. These are primarily based upon optical absorption and scattering effects and include infrared spectroscopy, Raman spectroscopy and optical coherence tomography (OCT), with other optical techniques such as photoacoustic spectroscopy (PAS) and polarimetry also reported. This review aims to discuss the current progress behind the most reported optical glucose sensing methods, theory and current limitations of optical sensing methods and the future technology development required to achieve an accurate optical-based glucose monitoring device.

Exploiting the optical sensing of fluorophore-tagged DNA nucleobases on hexagonal BN and Al-doped BN sheets: a computational study

The computational result reveals the distinction between absorption and emission phenomena of nucleobases tagged with fluorophore on h-BN and aluminium doped h-BN nanosheets, which can be used as biosensing platforms for nucleic acids.

Efficient Chemical Surface Modification Protocol on SiO2 Transducers Applied to MMP9 Biosensing

The bioreceptor immobilization process (biofunctionalization) turns to be one of the bottlenecks when developing a competent and high sensitivity label-free biosensor. Classical approaches seem to be effective but not efficient. Although biosensing capacities are shown in many cases, the performance of the biosensor is truncated by the inefficacious biofunctionalization protocol and the lack of reproducibility. In this work, we describe a unique biofunctionalization protocol based on chemical surface modification through silane chemistry on SiO2 optical sensing transducers. Even though silane chemistry is commonly used for sensing applications, here we present a different mode of operation, applying an unusual silane compound used for this purpose (3-Ethoxydimethylsilyl)propylamine, APDMS, able to create ordered monolayers, and minimizing fouling events. To endorse this protocol as a feasible method for biofunctionalization, we performed multiple surface characterization techniques after all the process steps: Contact angle (CA), X-ray photoelectron spectroscopy (XPS), ellipsometry, and fluorescence microscopy. Finally, to evidence the outputs from the SiO2 surface characterization, we used those SiO2 surfaces as optical transducers for the label-free biosensing of matrix metalloproteinase 9 (MMP9). We found and demonstrated that the originally designed protocol is reproducible, stable, and suitable for SiO2-based optical sensing transducers.