1 research outputs found
Carbon Nanotubes and Algal Polysaccharides To Enhance the Enzymatic Properties of Urease in Lipid Langmuir–Blodgett Films
Algal
polysaccharides (extracellular polysaccharides) and carbon
nanotubes (CNTs) were adsorbed on dioctadecyldimethylammonium bromide
Langmuir monolayers to serve as a matrix for the incorporation of
urease. The physicochemical properties of the supramolecular system
as a monolayer at the air–water interface were investigated
by surface pressure–area isotherms, surface potential–area
isotherms, interfacial shear rheology, vibrational spectroscopy, and
Brewster angle microscopy. The floating monolayers were transferred
to hydrophilic solid supports, quartz, mica, or capacitive electrolyte–insulator–semiconductor
(EIS) devices, through the Langmuir–Blodgett (LB) technique,
forming mixed films, which were investigated by quartz crystal microbalance,
fluorescence spectroscopy, and field emission gun scanning electron
microscopy. The enzyme activity was studied with UV–vis spectroscopy,
and the feasibility of the thin film as a urea sensor was essayed
in an EIS sensor device. The presence of CNT in the enzyme–lipid
LB film not only tuned the catalytic activity of urease but also helped
to conserve its enzyme activity. Viability as a urease 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 are related to
the synergism between the compounds on the active layer, leading to
a surface morphology that allowed fast analyte diffusion owing to
an adequate molecular accommodation, which also preserved the urease
activity. This work demonstrates the feasibility of employing LB films
composed of lipids, CNT, algal polysaccharides, and enzymes as EIS
devices for biosensing applications