Films of Manganese Oxide Nanoparticles with Polycations or Myoglobin from Alternate-Layer Adsorption

Abstract

Alternate adsorption of manganese oxide nanoparticles with polycations poly(dimethyldiallylammonium) (PDDA) or myoglobin (Mb) onto silver, quartz, and rough pyrolytic graphite gave stable, porous, ultrathin films. Quartz crystal microbalance (QCM) and UV-vis absorbance revealed regular film growth at each adsorption step for MnO2 and PDDA and for SiO2 nanoparticles and Mb. Scanning electron microscopy of MnO2/PDDA films showed smooth surfaces on the 20 nm scale and cross sections consistent with individual nanoparticles. QCM during growth of films of Mb and MnO2 reflected a competition for adsorption of the protein by the film surface and dispersed MnO2 nanoparticles. Nevertheless, films of Mb and MnO2 up to 30 nm thick on rough pyrolytic graphite electrodes could be constructed. These novel films featured reversible interconversion of the protein's heme Fe III /Fe II redox couple with 10 electroactive layers of protein, considerably more than for polyion-Mb films on smooth gold (ca. 1.3 electroactive layers), and coiled PSS/Mb films on rough graphite (7 electroactive layers). Shifts in redox potential caused by CO complexation of the heme Fe II , BET specific areas, and electrochemically driven catalytic reduction of oxygen suggest that the Mb/MnO2 films are highly porous to gas molecules. To our knowledge, these films represent the first nanofabrication of inorganic particles with functional proteins by the layer-by-layer method. † Part of the Special Issue "Colloid Science Matured, Four Colloid Scientists Turn 60 at the Millennium".

Redox Protein-Polymer Films for Simultaneous Determination of Ascorbic Acid and Hydrogen Peroxide

“…From previous studies with similar systems adsorption reached saturation in between 10 -20 min. 32 This time for the assembly of individual layers provided stable growth with repeatable steps as monitored by QCM at every adsorption cycle.…”

Fabrication of a Nanobiocomposite Film Containing Heme Proteins and Carbon Nanotubes on a Choline Modified Glassy Carbon Electrode: Direct Electrochemistry and Electrochemical Catalysis

“…As shown in Figure 5A, curve b, when the solution was open to the air, a new reduction peak at about À 0.17 V was appeared, accompanied by the disappearance of the oxidation peak of Mb heme Fe(II), suggesting the Mb heme Fe(II) had reacted with oxygen. Moreover, the potential of O 2 catalytic reduction shifts to potentials more positive than that of Mb-carboxymethyl cellulose (CMC) film (À 0.40 V) [10], Mb/sol-gel film (À 0.31 V) [46], and Mb/MnO 2 /Polycation film (À 0.24 V) [50]. Furthermore, the more the amount of oxygen in the solution is, the smaller the peak current correspondingly, as shown in Figure 5A, c, d, e. The catalytic efficiency can be expressed as the ratio of the reduction peak current of Mb heme Fe(III) in the presence (I c ) and absence of oxygen (I d ), I c /I d , decreased with increase of scan rate (data not shown).…”

Electroactive Cytochrome c Multilayers within a Polyelectrolyte Assembly

“…Other reported multilayer systems with myoglobin rely on rough surfaces, the use of nanoparticles, and a non-natural function of this transport protein (electron transfer instead of its transport function). [21,22] Our system offers new possibilities particularly for biosensing, where cyt.c electrodes have been applied to the quantification of oxygen radicals. [17] For this purpose, the use of a multilayer sensor with higher amounts of electroactive cyt.c can be expected to yield a significantly enhanced sensitivity.…”