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Biopolymers are an attractive green alternative to conventional polymers, owing to their excellent biocompatibility and biodegradability. However, their amorphous and nonconductive nature limits their potential as active biosensor material/substrate. To enhance their bio-analytical performance, biopolymers are combined with conductive materials to improve their physical and chemical characteristics. We review the main advances in the field of electrochemical biosensors, specifically the structure, approach, and application of biopolymers, as well as their conjugation with conductive nanoparticles, polymers and metal oxides in green-based noninvasive analytical biosensors. In addition, we reviewed signal measurement, substrate bio-functionality, biochemical reaction, sensitivity, and limit of detection (LOD) of different biopolymers on various transducers. To date, pectin biopolymer, when conjugated with either gold nanoparticles, polypyrrole, reduced graphene oxide, or multiwall carbon nanotubes forming nanocomposites on glass carbon electrode transducer, tends to give the best LOD, highest sensitivity and can detect multiple analytes/targets. This review will spur new possibilities for the use of biosensors for medical diagnostic tests.

This study improves the water solubility and cellular uptake of guanosine (GuN) through an inclusion complexation with cyclodextrin derivatives (CDs), namely β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and sulfobutyl ether-β-cyclodextrin (SBE-β-CD). Inclusion complexes of GuN and CDs are synthesized in a 1:1 stoichiometric ratio with binding constants calculated using the Benesi-Hildebrand method. Characterizations of the prepared solid complexes using FTIR, XRD, TGA-DSC, and SEM indicate that GuN is found inside the cavity of the CDs. Moreover, in silico molecular modeling analysis identifies the most favorable binding interactions of GuN deeply encapsulated in the hydrophobic cavities of the CDs, as validated by PatchDock and FireDock servers. In addition, human breast cancer MCF-7 cell activity indicates that the SBE-β-CD:GuN complex displays better cell viability and cellular uptake than GuN or other inclusion complexes of β-CD:GuN and HP-β-CD:GuN., (Copyright © 2019 Elsevier Ltd. All rights reserved.)