Two-step fabrication of nanoporous copper films with tunable morphology for SERS application

peer-reviewedIt is important to design and fabricate nanoporous metals (NPMs) with optimized microstructures for specific applications. In this contribution, nanoporous coppers (NPCs) with controllable thicknesses and pore sizes were fabricated via the combination of a co-sputtering of Cu/Ti with a subsequent dealloying process. The effect of dealloying time on porous morphology and the corresponding surface enhanced Raman scattering (SERS) behaviors were systematically investigated. Transmission electron microscopy (TEM) identified the presences of the gaps formed between ligaments and also the nanobumps on the nanoparticle-aggregated ligament surface, which were likely to contribute as the “hot spots” for electromagnetic enhancement. The optimal NPC film exhibited excellent SERS performance towards Rhodamine 6G (R6G) with a low limiting detection (10−9 M), along with good uniformity and reproducibility. The calculated enhancement factor of ca. 4.71 × 107 was over Au substrates and comparable to Ag systems, promising the proposed NPC as a cheap candidate for high-performance SERS substrate

A continuous fluidic bioreactor utilising electrodeposited silica for lipase immobilisation onto nanoporous gold

An electrochemically triggered sol-gel process was used to generate a thin silica layer for the immobilisation of lipase from Thermomyces lanuginosus onto dealloyed nanoporous gold (NPG). The catalytic response of the entrapped lipase was examined using the hydrolysis of 4-nitrophenyl butyrate (4-NPB) as a model reaction. For the electrodeposition process, parameters including the deposition time and the concentration of lipase affected the observed catalytic activity. A deposition time of 180 s and a lipase concentration of 3 mg mL− 1 were used to prepare the optimised electrode. The operational stability of the silica immobilised enzyme was enhanced on NPG in comparison to that on planar gold, which may arise from confinement of the enzyme in the porous structure. The modified electrodes were incorporated into a 3D printed flow cell with conversion efficiencies of up to 100% after 8 cycles

Immobilization of Redox Enzymes on Nanoporous Gold Electrodes: Applications in Biofuel Cells

Nanoporous gold (NPG) electrodes were prepared by dealloying sputtered gold:silver alloys. Electrodes of different thicknesses and pore sizes areas were prepared by varying the temperature and duration of the dealloying procedure; these were then used as supports for FAD‐dependent glucose dehydrogenase (GDH) (Glomorella cingulata) and bilirubin oxidase (BOx) (Myrothecium verrucaria). Glucose dehydrogenase was immobilized by drop‐casting a solution of the enzyme with an osmium redox polymer together with a crosslinked polymer, whereas bilirubin oxidase was attached covalently through carbodiimide coupling to a diazonium‐modified NPG electrode. The stability of the bilirubin‐oxidase‐modified NPG electrode was significantly improved in comparison with that of a planar gold electrode. Enzyme fuel cells were also prepared; the optimal response was obtained with a BOx‐modified NPG cathode (500 nm thickness) and a GDH‐modified anode (300 nm), which generated power densities of 17.5 and 7.0 μW cm−2 in phosphate‐buffered saline and artificial serum, respectively.This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no. 607793 (BIOENERGY).Peer reviewe

Immobilization of redox enzymes on nanoporous gold electrodes: applications in biofuel cells

Nanoporous gold (NPG) electrodes were prepared by dealloying sputtered gold: silver alloys. Electrodes of different thicknesses and pore sizes areas were prepared by varying the temperature and duration of the dealloying procedure; these were then used as supports for FAD-dependent glucose dehydrogenase (GDH) (Glomorella cingulata) and bilirubin oxidase (BOx) (Myrothecium verrucaria). Glucose dehydrogenase was immobilized by drop-casting a solution of the enzyme with an osmium redox polymer together with a crosslinked polymer, whereas bilirubin oxidase was attached covalently through carbodiimide coupling to a diazonium-modified NPG electrode. The stability of the bilirubin-oxidase-modified NPG electrode was significantly improved in comparison with that of a planar gold electrode. Enzyme fuel cells were also prepared; the optimal response was obtained with a BOx-modified NPG cathode (500 nm thickness) and a GDH-modified anode (300 nm), which generated power densities of 17.5 and 7.0 mu W cm(-2) in phosphate-buffered saline and artificial serum, respectively

Immobilization of redox enzymes on nanoporous gold electrodes: applications in biofuel cells

Nanoporous gold (NPG) electrodes were prepared by dealloying sputtered gold: silver alloys. Electrodes of different thicknesses and pore sizes areas were prepared by varying the temperature and duration of the dealloying procedure; these were then used as supports for FAD-dependent glucose dehydrogenase (GDH) (Glomorella cingulata) and bilirubin oxidase (BOx) (Myrothecium verrucaria). Glucose dehydrogenase was immobilized by drop-casting a solution of the enzyme with an osmium redox polymer together with a crosslinked polymer, whereas bilirubin oxidase was attached covalently through carbodiimide coupling to a diazonium-modified NPG electrode. The stability of the bilirubin-oxidase-modified NPG electrode was significantly improved in comparison with that of a planar gold electrode. Enzyme fuel cells were also prepared; the optimal response was obtained with a BOx-modified NPG cathode (500 nm thickness) and a GDH-modified anode (300 nm), which generated power densities of 17.5 and 7.0 mu W cm(-2) in phosphate-buffered saline and artificial serum, respectively