Conjugated Polymers Blended with Lipids and Galactosidase as Langmuir–Blodgett Films To Control the Biosensing Properties of Nanostructured Surfaces

Abstract

The structure of enzymes must be conserved when incorporated in nanoelectronic devices because their activity determines the function of the device as sensors. Among the systems that can retain their conformational structures, Langmuir–Blodgett (LB) films can be useful to exploit the construction of bioelectronic devices organized at the molecular level because biological and polymeric materials can be coupled as ultrathin films for biosensors and actuators. In this paper, we immobilized a β-galactosidase enzyme in the LB films of stearic acid and the conjugated polymer poly­[(9,9-dioctylfluorene)-co-thiophene]. After the characterization of the floating films using tensiometry, vibrational spectroscopy, and Brewster angle microscopy, they were transferred to solid supports as LB films, and the catalytic activity of the enzyme could be preserved as analyzed using UV–vis spectroscopy. We noted that the presence of a supramolecular structure formed in the LB films not only conserved the enzyme activity but also exhibited regular and distinctive output signals in all molecular architectures employed in this work. These results are related to the synergism between the compounds on the active layer associated with a surface morphology that facilitated the analyte diffusion because of an adequate molecular accommodation of all components. This work then demonstrates the viability of employing LB films composed of lipids, enzymes, and synthetic polymers as devices for biosensing applications.

Cationic Polythiophene-based Colorimetric Assay for Probing the Activity of Protein Kinase A

“…Conjugated polymers, with robust light-harvesting ability and optical signal amplification effect, 18,19 has been utilized in bioimaging 20,21,22 and biosensing. 23,24 Water-soluble polythiophene derivatives display irregular curly conformation and exbibits yellow color in its natural state. Once formed relative planar conformation, polythiophene aqueous solution will turn pink in color.…”

Self‐Assembled Polymeric Membranes and Nanoassemblies on Surfaces: Preparation, Characterization, and Current Applications

“…When using this approach with an asymmetric ABC block polymer, the film thickness of the dry and wet state can be fine‐tuned . By controlling the surface pressure on the through, high control over the assembly and the membrane was achieved, and high packing densities have been reached by just increasing the surface pressure without drifting away from the monolayer assembly conditions . Asymmetric membranes have also been reported by targeting the balance between surface pressure and surface chemistry .…”

“…For instance, PNIPAM‐TlAa was deposited to promote aldolase insertion providing covalent bonding points without the use of further membrane crosslinking . Poly[9,9‐dioctylfluorene‐ co ‐thiophene] was used in combination with stearic acid for the immobilization of β‐galattosidase: all three components were deposited at the air water interface and compressed to a film, which was subsequently transferred to a solid support . More focus has been put onto transmembrane proteins and their interaction with hydrophobic domains.…”

Surface Chemistry Studies on the Formation of Mixed Stearic Acid/Phenylalanine Dehydrogenase Langmuir and Langmuir–Blodgett Films

“…With these ideas in mind, we investigated the influence of stearic acid (HSt) as a matrix for the immobilization of PheDH. HSt is a relatively inexpensive fatty acid reported to be easily transferred as multilayers to solid supports as LB films. ,, For this investigation, we employed surface pressure and surface potential–area isotherms and spectroscopic and morphological measurements.…”

“…HSt is a relatively inexpensive fatty acid reported to be easily transferred as multilayers to solid supports as LB films. 12,15,16 For this investigation, we employed surface pressure and surface potential−area isotherms and spectroscopic and morphological measurements.…”