Hydrophobic interactions leading to a complex interplay between bioelectrocatalytic properties and multilayer meso-organization in layer-by-layer assemblies

Abstract

The present study explores the development of mesostructured bioelectrochemical interfaces with accurate compositional and topological control of the supramolecular architecture through the layer-by-layer assembly of ternary systems based on poly(allylamine) containing an osmium polypyridyl complex (OsPA), an anionic surfactant, sodium dodecyl sulfate (SDS) or sodium octodecyl sulfate (ODS), and glucose oxidase (GOx). We show that the introduction of the anionic surfactant allows a sensitive increase of the polyelectrolyte and the enzyme uptake at pH 7.0, enhancing its catalytic behavior in the presence of glucose as compared to the surfactant-free system (OsPA/GOx)n constructed at the same pH. Structural characterization of the multilayer films was performed by means of grazing-incidence small-angle X-ray scattering (GISAXS), which showed the formation of mesostructured domains within the composite assemblies. Experimental results indicate that the balance between ionic and hydrophobic interactions plays a leading role not only in the construction of the self-assembled system but also in the functional properties of the bioactive interface. The structure of the ternary multilayered films depends largely on the length of the alkyl chain of the surfactant. We show that surfactants incorporated into the film also play a role as chemical entities capable of tuning the hydrophobicity of the whole assembly. In this way, the deliberate introduction of short-range hydrophobic forces was exploited as an additional variable to manipulate the adsorption and coverage of protein during each assembly step. However, the integration of long-chain surfactants may lead to the formation of very well-organized interfacial architectures with poor electron transfer properties. This, in turn, leads to a complex trade-off between enzyme coverage and redox wiring that is governed by the meso-organization and the hydrophobic characteristics of the multilayer assembly.

Supramolecular electrode assemblies for bioelectrochemistry

“…For example, osmium polypyridyl complex, sodium dodecyl sulfate (SDS), and glucose oxidase were used to form a multicomposite multilayer assembly that was driven by hydrophobic as well as electrostatic interactions. 26 Cyclic voltammetry showed a linear increase of the redox signals up to 4 ‘dipping cycles’, while a 3-fold increase in glucose oxidase coverage was seen with SDS that led to a 9-fold increase in sensitivity for the detection of glucose at a sensitivity of 18.4 μA cm –2 per layer. 26 …”

“…26 Cyclic voltammetry showed a linear increase of the redox signals up to 4 ‘dipping cycles’, while a 3-fold increase in glucose oxidase coverage was seen with SDS that led to a 9-fold increase in sensitivity for the detection of glucose at a sensitivity of 18.4 μA cm –2 per layer. 26 …”

Molecular Design of Solid‐State Nanopores: Fundamental Concepts and Applications

“…In recent years, the modification of solid‐state nanopores via polyelectrolyte assembly/adsorption has gained increasing interest . The LbL assembly of polyelectrolytes represents a very simple and versatile chemical method to create functional thin films with nanoscale precision . This functionalization method is based on the alternate deposition of polyanions and polycations on solid surfaces leading to the formation of polyelectrolyte multilayers .…”

Empowering Bioelectronics with Supramolecular Nanoarchitectonics: PEDOT-Based Organic Electrochemical Transistors with Tunable Electronic Properties

“…31 For instance, it has been shown that the presence of surfactants in LbL assemblies has a strong impact on structure−property relationship composite. 30,32,33 On the other hand, the surfactant character may disperse building blocks and enhance the interchain interactions between conducting polymer. 34 In this sense, the integration of CTAB into the LbL structure may promote structural changes with implications on the electronic conductivity of the films compared with the long chain polyelectrolyte PDADMAC.…”

“…Both cationic blocks are electrochemically inactive and have positive charge consisting of quaternary amines but with different mesogenic and surfactant characters, which may lead to different structure. , On the one side, the mesogenic character is the property of some compounds to promote molecular order or spatial orientation of the structures generated in combination with other reagents such as polymers . For instance, it has been shown that the presence of surfactants in LbL assemblies has a strong impact on structure–property relationship composite. ,, On the other hand, the surfactant character may disperse building blocks and enhance the interchain interactions between conducting polymer . In this sense, the integration of CTAB into the LbL structure may promote structural changes with implications on the electronic conductivity of the films compared with the long chain polyelectrolyte PDADMAC.…”