Polymer protective layers possessing high flexibility and compatibility with substrates show potential to stabilize zinc anodes. However, inferior electronic or ionic conductivity and limited structural tunability restrain electrochemical reaction kinetics and targeted optimization of polymers. Here we present a mixed-conductive polythiophene coating, namely pgBTTT, with tailored glycol side chains. Compared with its alkyl chain counterpart pBTTT, pgBTTT exhibits superior electronic and ionic conductivity, and zincophilicity to facilitate uniform zinc deposition. Moreover, the strong coordination between the thiophene main chains of pgBTTT and zinc ions accelerates ion transport and diffusion through building exclusive channels. Correspondingly, the cycling stability of Zn‖Zn symmetric cells is improved with a small polarization voltage of 30 mV at 2 mA cm−2. The full battery with the NH4VO4 cathode delivers a high specific capacity of 528 mA h g−1 at 0.2 A g−1 with a low capacity-fading rate of 0.0183% per cycle after 1000 cycles.
Enzyme-based electrochemical biosensors play an important role in point-of-care diagnostics for personalized medicine. For such devices, lipid cubic phases (LCP) represent an attractive method to immobilize enzymes onto conductive surfaces with no need for chemical linking. However, research has been held back by the lack of effective strategies to stably co-immobilize enzymes with a redox shuttle that enhances the electrical connection between the enzyme redox center and the electrode. In this study, we show that a monoolein (MO) LCP system doped with an amphiphilic redox mediator (ferrocenylmethyl)dodecyldimethylammonium bromide (Fc12) can be used for enzyme immobilization to generate an effective biosensing platform. Small-angle X-ray scattering (SAXS) showed that MO LCP can incorporate Fc12 while maintaining the Pn3m symmetry morphology. Cyclic voltammograms of Fc12/MO showed quasi-reversible behavior, which implied that Fc12 was able to freely diffuse in the lipid membrane of LCP with a diffusion coefficient of 1.9 ± 0.2 × 10-8 cm2 s-1 at room temperature. Glucose oxidase (GOx) was then chosen as a model enzyme and incorporated into 0.2%Fc12/MO to evaluate the activity of the platform. GOx hosted in 0.2%Fc12/MO followed Michaelis-Menten kinetics toward glucose with a KM and Imax of 8.9 ± 0.5 mM and 1.4 ± 0.2 μA, respectively, and a linearity range of 2-17 mM glucose. Our results therefore demonstrate that GOx immobilized onto 0.2% Fc12/MO is a suitable platform for the electrochemical detection of glucose.
3 October 2024 in Journal of Colloid and Interface Science
Electrically conductive hydrogels (ECHs) combine the electrical properties of conductive materials with the unique features of hydrogels. They are attractive for various biomedical applications due to their smart response to electrical fields. Owing to their distinctive properties, such as biocompatibility, thermosensitivity and self-assembling behaviour, Pluronics can be adopted for the generation of hydrogels for biomedical applications. Here, innovative self-assembling ECHs holding antimicrobial properties for biomedical applications are developed, providing a full characterization of their macroscopic and microscopic properties. The rheological, morphological, and structural properties of Pluronic F68 (PF68) in the presence of conductive poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) are studied to optimize the synthesis of novel biocompatible and electrically conductive hydrogels. The addition of silver (Ag) flakes to the aqueous samples of PF68/PEDOT:PSS is used to further enhance the systems electrical conductivity and antimicrobial potency. Aqueous optimal samples with 45 wt% PF68 and different PEDOT:PSS/silver contents are investigated by means of experimental rheology and small-angle X-ray scattering (SAXS), to unveil the influence of both PEDOT:PSS and silver on the phase diagram, macroscopic flow properties, and morphology of the Pluronic-based systems. The presence of PEDOT:PSS and silver flakes endows Pluronic systems with high conductive properties, while preserving the same self-assembly features of PF68 in water. Moreover, the functionalisation with silver flakes confers antimicrobial properties to the ECHs, as demonstrated by growth inhibition of the multi-drug resistant bacterium Staphylococcus aureus. The use of PF68 in this work provides a novel route for the synthesis of innovative ECHs, whose functionalities such as self-assembling behaviour, biocompatibility, conductivity, and bioactivity may inspire future avenues in the biomedical field.
Implantable and wearable bioelectronic systems can enable tailored therapies for the effective management of long-term diseases, thus minimising the risk of associated complications. In this context, glucose fuel cells hold great promise as in- or on-body energy harvesters for ultra-low-power bioelectronics and as self-powered glucose sensors. We report here the generation of gold nanostructures through a gold electrodeposition method in a soft template for the abiotic electrocatalysis of glucose in glucose fuel cells. Two different types of soft template were used: a lipid cubic phase-based soft template composed of Phytantriol and Brij®-56, and an emulsion-based soft template composed of hexane and sodium dodecyl sulphate (SDS). The resulting gold structures were first characterised by SAXS, SEM and TEM to elucidate their structure, and then their electrocatalytic activity towards glucose was compared in both a three-electrode set-up and in a fuel cell set-up. The Phytantriol/Brij®-56 template led to a nanofeather-like Au structure, while the hexane/SDS template led to a nanocoral-like Au structure. These templated electrodes exhibited similar electrochemical active surface areas (0.446 cm2 with a roughness factor (RF) of 14.2 for Phytantriol/Brij®-56 templated nanostructures and 0.421 cm2 with an RF of 13.4 for hexane/SDS templated nanostructures), and a sensitivity towards glucose of over 7 μA mM−1 cm−2. When tested as the anode of an abiotic glucose fuel cell (in a phosphate-buffered solution with a glucose concentration of 6 mM), a maximum power density of 7 μW cm−2 was reached; however the current density in the case of the fuel cell with the Phytantriol/Brij®-56 templated anode was approximately two times higher, reaching the value of 70 μA cm−2. Overall, this study demonstrates two simple, cost-effective and efficient strategies to manipulate the morphology of gold nanostructures, and thus their catalytic property, paving the way for the successful manufacturing of functional abiotic glucose fuel cells.
19 September 2024 in Advanced Materials Interfaces
Ordered and well‐interconnected 3D electrode nanostructures open up exciting perspectives in catalysis, sensing and energy harvesting. Here, highly ordered 3D nano‐sized Pt mesoporous structures based on the I‐Wrapped Package (I‐WP) architecture with 13.5 nm unit cell size, previously unreported for metal nanomaterials, are presented. The samples are synthetized by soft‐template electrodeposition, using the body‐centred cubic (BCC) lyotropic crystalline micellar phase of Pluronic F68 as the template. The specific surface area of the resulting Pt nanoarchitecture is 36 ± 13 m2 g−1. The oxygen reduction reaction kinetic current is 0.98 mA cm−2; the current density normalized by the electrochemical active surface area and the weight of deposited Pt are 0.92 mA cm−2 and 153.53 A g−1, respectively, showing superior properties than conventional Pt nanostructures produced by surfactant templates. These results suggest a nanostructure based on the topology of the I‐WP minimal surface, representing the first case at this length scale from a metallic material, opening up new research directions in fundamental physics based on predicted thermal and phononic properties for this topology. The water‐based template provides a chemical‐free, eco‐friendly route for ordered mesoporous conductive nanomaterials manufacturing, inspiring future trends in the field.