3 research outputs found
Electrogeneration of platinum nanoparticles in a matrix of dendrimer-carbon nanotubes
Hybrid materials with enhanced properties can now be obtained by combining nanomaterials such as carbon nanotubes and metallic nanoparticles, where the main challenge is to control fabrication conditions. In this study, we demonstrate that platinum nanoparticles (PtNps) can be electrogenerated within layer-by-layer (LbL) films of polyamidoamine (PAMAM) dendrimers and single-walled carbon nanotubes (SWCNTs), which serve as stabilizing matrices. The advantages of the possible control through electrogeneration were demonstrated with a homogeneous distribution of PtNps over the entire surface of the PAMAM/SWCNT LbL films, whose electroactive sites could be mapped using magnetic force microscopy. The Pt-containing films were used as catalysts for hydrogen peroxide reduction, with a decrease in the reduction potential of 60 mV compared to a Pt film deposited onto bare ITO. By analyzing the mechanisms responsible for hydrogen peroxide reduction, we ascribed the enhanced catalytic activity to synergistic effects between platinum and carbon in the LbL films, which are promising for sensing and fuel cell applications.CNPq (480400/2010-5, 471794/2012-0)FAPEMIG (APQ-01357-11)FAPESPRede CAPES de NanoBiotecnologia - nBioNet Films and Sensor
Carbon Nanotubes Arranged As Smart Interfaces in Lipid Langmuir–Blodgett Films Enhancing the Enzymatic Properties of Penicillinase for Biosensing Applications
In
this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid
Langmuir and Langmuir–Blodgett (LB) films to enhance the enzyme
catalytic properties. Adsorption of the penicillinase and CNTs at
dimyristoylphosphatidic acid (DMPA) monolayers at the air–water
interface was investigated by surface pressure–area isotherms,
vibrational spectroscopy, and Brewster angle microscopy. The floating
monolayers were transferred to solid supports through the LB technique,
forming mixed DMPA-CNTs-PEN films, which were investigated by quartz
crystal microbalance, vibrational spectroscopy, and atomic force microscopy.
Enzyme activity was studied with UV–vis spectroscopy and the
feasibility of the supramolecular device nanostructured as ultrathin
films were essayed in a capacitive electrolyte–insulator–semiconductor
(EIS) sensor device. The presence of CNTs in the enzyme–lipid
LB film not only tuned the catalytic activity of penicillinase but
also helped conserve its enzyme activity after weeks, showing increased
values of activity. Viability as penicillin sensor was demonstrated
with capacitance/voltage and constant capacitance measurements, exhibiting
regular and distinctive output signals over all concentrations used
in this work. These results may be related not only to the nanostructured
system provided by the film, but also to the synergism between the
compounds on the active layer, leading to a surface morphology that
allowed a fast analyte diffusion because of an adequate molecular
accommodation, which also preserved the penicillinase activity. This
work therefore demonstrates the feasibility of employing LB films
composed of lipids, CNTs, and enzymes as EIS devices for biosensing
applications