A bacteriorhodopsin-based biohybrid solar cell using carbon-based electrolyte and cathode components.

There is currently a high demand for energy production worldwide, mainly producing renewable and sustainable energy. Bio-sensitized solar cells (BSCs) are an excellent option in this field due to their optical and photoelectrical properties developed in recent years. One of the biosensitizers that shows promise in simplicity, stability and quantum efficiency is bacteriorhodopsin (bR), a photoactive, retinal-containing membrane protein. In the present work, we have utilized a mutant of bR, D96N, in a photoanode-sensitized TiO2 solar cell, integrating low-cost, carbon-based components, including a cathode composed of PEDOT (poly(3,4-ethylenedioxythiophene) functionalized with multi-walled carbon nanotubes (CNT) and a hydroquinone/benzoquinone (HQ/BQ) redox electrolyte. The photoanode and cathode were characterized morphologically and chemically (SEM, TEM, and Raman). The electrochemical performance of the bR-BSCs was investigated using linear sweep voltammetry (LSV), open circuit potential decay (VOC), and impedance spectroscopic analysis (EIS). The champion device yielded a current density (JSC) of 1.0 mA/cm2, VOC of -669 mV, a fill factor of ~24 %, and a power conversion efficiency (PCE) of 0.16 %. This bR device is one of the first bio-based solar cells utilizing carbon-based alternatives for the photoanode, cathode, and electrolyte. This may decrease the cost and significantly improve the device's sustainability.

An Electronic and Optically Controlled Bifunctional Transistor Based on a Bio-Nano Hybrid Complex.

We report an electronically and optically controlled bioelectronic field-effect transistor (FET) based on the hybrid film of photoactive bacteriorhodopsin and electronically conducting single-walled carbon nanotubes (SWNTs). Two-dimensional (2D) crystals of bacteriorhodopsin form the photoactive center of the bio-nano complex, whereas one-dimensional (1D) pure SWNTs provide the required electronic support. The redshift in the Raman spectra indicates the electronic doping with an estimated charge density of 3 × 106 cm-2. The hybrid structure shows a conductivity of 19 µS/m and semiconducting characteristics due to preferential binding with selective diameters of semiconducting SWNTs. The bioelectronic transistor fabricated using direct laser lithography shows both optical and electronic gating with a significant on/off switch ratio of 8.5 and a photoconductivity of 13.15 µS/m. An n-type FET shows complementary p-type characteristics under light due to optically controlled, electronic doping by the "proton-pumping" bacteriorhodopsin. The fabricated bioelectronic transistor exhibits both electronically and optically well-controlled bifunctionality based on the functionalized hybrid electronic material.

Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes.

Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions. Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration. We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples. The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.