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In the wearable electrochemical biosensors, sensing signal duration is significantly dependent on the long-term stability of functional materials modified on the flexible substrate, the effect of pH changes of sweat on the sensing device and signal fluctuation caused by the bending of sensor. Here, we proposed a wearable biosensor based on the lactate-sensing membrane mainly constituted by Prussian blue (PB), reduced graphene oxide (rGO), Au nanoparticles and lactate oxidase (LOx). Based on the in-situ layer-by-layer spin-coating preparation method, the electrode surface was covered with an extensive and uniform PB/GO membrane with a high stability. After the electro-reduction of GO to rGO and the combination of urchin-like Au particles with sufficient tentacles to LOx, the sensing membrane showed the improved electron transport from the enzyme active center to the electrode. Therefore, the wearable biosensor achieved a high sensitivity of 40.6 μA mM−1 cm−2 in a range of 1–222 μM and a low sensitivity of 1.9 μA mM−1 cm−2 in a wide range of 0.222–25 mM, satisfying the requirement of the typical test. In addition, with the excellent running and mechanical stability, the lactate biosensor was successfully applied on volunteers' skin for real-time monitoring of perspiration in vivo. The results were comparable with ex vivo measurements achieved by a commercial lactate sensor. The wearable electrochemical biosensor provides a good candidate in the future for the evaluation of human sweat in sports and biomedical fields. [ABSTRACT FROM AUTHOR]

A PEDOT:PSS conductive hydrogel is incorporated with Prussian blue nanoparticles for the highly sensitive in vitro glucose detection and is applied as a skin patch on human subjects for the in vivo noninvasive monitoring of interstitial fluid (ISF) glucose via reverse iontophoresis technology. The biosensor achieves good correlation with the finger-stick blood glucose measurement. [Display omitted] • The PEDOT:PSS/DF/PB hydrogel possessed an excellent operating stability. • The hydrogel-based sensor showed a competitive sensitivity of 340.1 μA·mM−1·cm−2. • The wearable sensor noninvasively monitored the ISF glucose through RI-extraction. • The sensor showed good correlation with the results from commerical glucometer. Currently, there is no commercially-available noninvasive method for glucose monitoring in the interstitial fluid (ISF) mainly due to the measurement accuracy, sensitivity and/or the weak blood correlation. Here, we present an electrochemical biosensor based on PEDOT:PSS conductive hydrogel incorporated with Prussian blue nanoparticles (PBNPs) for the noninvasive and continuous monitoring of glucose on body. The hydrogel was prepared with the addition of dimethyl sulfoxide (DMSO) and Zonyl FS-300, which helped to improve the expanding of the polymer chains for the formation of better conductive and nanoporous networks. The hydrogel-based biosensor showed a low detection limit of 0.85 μM for glucose detection and high sensitivity up to 340.1 μA·mM−1·cm−2, which was about 10-fold higher than the counterparts based on agarose and hydroxyethyl methacrylate (HEMA) hydrogels. Furthermore, it provided good accuracy with commercial glucometer for the glucose detection in serum. More importantly, incorporated with the reverse iontophoresis (RI), the hydrogel was applied as a skin patch on human subject for the in vivo noninvasive and continuous monitoring of ISF-borne glucose. The results showed good correlation with that measured by blood glucometer. We believe such glucose biosensor paves the way to clinically wearable noninvasive glucose monitoring in diabetics. [ABSTRACT FROM AUTHOR]

• A hollow core-shell Cu(OH) 2 @Au@Co(OH) 2 composite is prepared by a simple template-engaged reaction. • The novel structure possesses highly enzymatic activity and long-term stability for glucose detection. • The sensor achieves comparable performance with commercial glucometer in serum test. A core-shell Cu(OH) 2 @Au@Co(OH) 2 nanocomposite with hollow nano-flower morphology fabricated by a facile and non-surfactant template-engaged reaction was applied for highly sensitive detection of glucose. The prussian blue analogues (PBA) of core-shell nanocubes (CuFe@Au@CoFe) were synthesized as the template through the accurate control of the reaction rate. In this nanocubes, Au nanoparticles for accelerating electron transfer rate were reduced at the interface of CoFe (core) and CuFe (shell) to improve their conductivity. These nanocubes were then etched controllably to form three-dimensional hollow nanoflowers stacked by nanosheets. It provided abundant electrode-electrolyte channels and high surface areas for OH− and glucoses adsorption and the following reactions. Due to the sandwich structure and synergic effect of the nanomaterials, the as-prepared sensors exhibited an ultrahigh sensitivity of 3427 μA mM-1 cm-2 for glucose detection, as well as a wide linear range of 0.001–5.2 mM with a low detection limit of 0.5 μM. In addition, the Cu(OH) 2 @Au@Co(OH) 2 nanocomposite showed long-term stability and good reproducibility for glucose detection in serum with comparable results as measured with commercial glucometer. We believe the nanocomposite provided a good candidate for glucometer in future clinical applications. [ABSTRACT FROM AUTHOR]