Ionic self-assembly of redox-active polyelectrolyte-surfactant complexes: mesostructured soft materials for electrochemical nanoarchitectonics

Abstract

Ionic self-assembly (ISA) has emerged as a powerful nanoarchitectonics strategy for constructing functional supramolecular materials through electrostatic interactions. This approach enables the formation of highly ordered nano- and mesostructures with tunable electrochemical properties. A key application of ISA lies in electroactive polyelectrolyte-surfactant complexes, which serve as dynamic platforms for biosensing and electrochemical devices. These materials, easily integrated onto electrodes via solution-based deposition techniques, offer tailored charge transport and redox activity. Their ability to incorporate metal nanoparticles and enzymes further expands their functionality, enabling the development of amperometric biosensors for highly sensitive biochemical detection. This review explores the principles of ISA-derived materials, emphasizing their role in electrochemical applications and their potential in next-generation biosensors.

Keywords: Nanoarchitectonics; bioelectrochemistry; electroactive materials; polyelectrolyte-surfactant complexes; self-assembly.

Graphical abstract

Figure 1.

(Left) Schematic depiction of PSS-Fc_n complex. (Right). Cyclic voltammograms of PSS-Fc8, PSS-Fc12, and PSS-Fc16 complexes measured at a scan rate of 0.2 V/s in 0.1 M NaCl solution (T = 25 °C). Reproduced from [95]. With permission from American Chemical Society.

Figure 2.

(a) Schematic depiction of complex preparation. (b) Stacking model for the complexes at room temperature. (c) XRD profiles of the PFS-(3,4,5)_nG1 (n = 12, 14, 16) complexes at room temperature. Reproduced from [97]. With permission from American Chemical Society.

Figure 3.

Schematic representation of the formation of hierarchically self-assembled architectures, illustrating the concept of structure-within-structure formation. Reproduced from [99]. With permission from American Chemical Society.

Figure 4.

Morphological characterization of 9-AOT. (a) AFM phase profile, scale bar = 200 nm. (b) SAXS scattering of the sample. (c) Structure of the complex. (d) TEM micrograph of microtomed sections (60 nm), annealed for 5 days at 130 °C (scale bar = 200 nm). Reproduced from [99]. With permission from American Chemical Society.

Figure 5.

(a) Structure of the complex 9-AOTF. (b) TEM micrograph of microtome sections at 60 nm. (c) SAXS patterns at small and large length scales. (d) AFM phase profile showing the cylinders after etching the organic block with an oxygen plasma. Reproduced from [99]. With permission from American Chemical Society.

Figure 6.

(a) Chemical structure of the hierarchical PFEMS₁₁₂-b-PFAMS(EO)₁₁₂ complex. (b) TEM micrographs of the microphase-separated PFEMS₁₁₂-b-PFAMS(EO)₁₁₂ complex at different magnifications. Reproduced from [101]. With permission from VCH-Wiley.

Figure 7.

GISAXS patterns for (PAA/surfactant)₇ assemblies prepared on Si (100) substrates with different CTA:FcCDA ratios. From top to bottom, molar fraction of FcCDA in solution: 0, 0.1, 0.3, 0.5 and 1. Reproduced from [103]. With permission from VCH-Wiley.

Figure 8.

(a) Cyclic voltammograms for assemblies (PAA/surfactants)₅ with different CTA:FcCDA ratios. From left to right: (PAA/CTA)₅, black; (PAA/CTA_0.9-FcCDA_0.1)₅, red; (PAA/CTA_0.7-FcCDA_0.3)₅, green; (PAA/CTA_0.5-FcCDA_0.5)₅, blue; and (PAA/FcCDA)₅, brown. Voltammogram cycle number: 1, 5, 10, 15, 20, 25 and 30. Scan rate: 50 mV/s. (b) Left: scheme of the EQCM-D experimental setup. Right: EQCM-D response for a (PAA/CTA_0.5-FcCDA_0.5)₇/PAA assembly. Current density (j) and frequency, δf, as a function of the applied potential. Supporting electrolyte:100 mm NaCl. Scan rate: 25 mV/s. Adapted from [103] and [104] with permission from Wiley-VCH Verlag GmbH & Co. And Elsevier, respectively.

Figure 9.

Chemical structure of (a) 2C₁₆V²⁺/PSS⁻ and (b) 2C₁₂SO₃⁻/polyV²⁺ complexes.

Figure 10.

(a) Transmission electron micrograph and (b) and the illustration of the intersection of the 2C₁₆V²⁺/PSS film. Reproduced from [114]. With permission from American Chemical Society.

Figure 11.

X-ray diffraction patterns of the complexes made from different PANi:DBSA weight ratios (doping temperature: 100°C; doping time: 20 min). Reproduced from [127]. With permission from VCH-Wiley.

Figure 12.

Chemical structure of the PANI-DBSA complex.

Figure 13.

Chemical structure BEHP – oligomer complex.

Figure 14.

(a) GIXS pattern for the TANI(BEHP)_0.5 film (b) interpretation of the contents of the hexagonal TANI(BEHP)_0.5 unit cell in the ab- plane; and (c) schematic of the TANI(BEHP)_0.5 packing structure showing the orientation relative to the underlying substrate. Reproduced from [132]. With permission from Royal Society of Chemistry.

Figure 15.

Schematic depiction of the preparation procedure and structure of the poly(3-aminobenzylamine) (PABA) and monododecyl phosphate (DP) films. Reproduced from [149]. With permission from Royal Society of Chemistry.

Figure 16.

(a) X-ray reflectivity (XRR) and (b) grazing-incidence small-angle X-ray scattering (GISAXS) characterization of 1:5 PABA – DP films. Reproduced from [149]. With permission from Royal Society of Chemistry.

Figure 17.

Voltammetric response of a PABA–DP-coated gold electrode at different sweep rates from 10 to 120 mV s⁻¹ in sulfuric acid solution. (a) PABA – DP 1:2, (b) PABA – DP 1:10. (c) Comparison of the voltammograms for both electrodes at the same scale. Reproduced from [149]. With permission from Royal Society of Chemistry.

Figure 18.

(a) X-ray diffraction pattern of polypyrrole-octanesulfonate. The inset shows a comparison of the fitted theoretical line shape with the experimental one. (b) Plot of the fitted d-values of the first X-ray diffraction peak for a series of polypyrrole sulfates versus number of carbon atoms, n, in one n-alkyl chain of the incorporated anionic surfactant. Reproduced from [151]. With permission from VCH-Wiley.

Figure 19.

(a) Schematic representation of the structure of PEDOT:PSS/CTAB self-assembled complex. (b) Film thickness obtained by ellipsometry of (PEDOT:PSS/PDADMAC)_n (red) and (PEDOT:PSS/CTAB)_n (blue) assemblies as a function of the number of LbL cycles (n). (c) Electrical resistance of (Pedot:pss/pdadmac)n (red) and (Pedot:pss/ctab)n (blue) assemblies. d) Transfer curves (solid line, left-Y) and transconductance curves (dashed line, right-Y) for (PEDOT:PSS/CTAB)_n organic electrochemical transistors (OECTs). Reproduced from [159]. With permission from American Chemical Society.

Figure 20.

(a) Schematic of the different layers constituting the lamellar assembly: ionic layers correspond to the polyelectrolyte and dodecyl sulfate head groups, whereas the alkane layers correspond to interdigitated hydrophobic tails (dodecyl groups). (b) X-ray reflectivity data for (a) PA-DS and (b) OsPA-DS films measured under ambient conditions. (c) GISAXS patterns corresponding to (a) PA-DS and (b) OsPA-DS films measured at under ambient conditions. Films were spin-coated on Si(100) substrates. Reproduced from [165]. With permission from Elsevier BV.

Figure 21.

Cyclic voltammetry of the OsPA-DS film on ITO at 100 mV s⁻¹ in 20 mm Tris-HCl buffer, pH 7.4 and 0.1 M KNO₃. Film thickness: 150  ±  20 nm. Reproduced from [165]. With permission from Elsevier BV.

Figure 22.

Representation of the preparation procedure of (OsPA–DS/GOx) films.

Figure 23.

GISAXS patterns obtained from OsPA-DS_org (a and b) and OsPA-DS_aq (c and d) films measured under 0% (a and c) and 95% (b and d) relative humidity conditions. Films were spin-coated on Si(100) substrates reproduced from [169]. With permission from Elsevier BV.

Figure 24.

(a) Cyclic voltammogram at 10 mV s⁻¹ for OsPA – DS_aq (black line, current scale on the right y-axis), and OsPA – DS_org (dotted line, current scale on the left y-axis). (b) Current response of OsPA – DS_aq (white squares) and OsPA – DS_org (black circles) to low glucose concentrations. Inset: the extended plot until 50 mm glucose concentration. Reproduced from [169]. With permission from Elsevier BV.

Figure 25.

Simplified schematic of the H₂O₂-responsive interfacial supramolecular architecture. Redox-active Con A and HRP are spontaneously assembled via molecular recognition processes onto the redox-active glycopolyelectrolyte − surfactant supramolecular thin film. The figure displays the constituting building blocks participating in the generation of the biolectrochemical signal in the presence of hydrogen peroxide as well as a simplified view of their organization in the interfacial architecture. Source: Cortez et al. Anal. Chem. 2013, 85, 2414. Reproduced with permission of American Chemical Society. The figure also includes cyclic voltammograms describing the electrochemical response of gold electrode modified with a GOsPA-DS/Os-ConA/HRP assembly in the absence and in the presence of H₂O₂. Reproduced from [175]. With permission from Royal Society of Chemistry.

Figure 26.

Representation of the preparation procedure of OsPA-DS-AuNP films.

Figure 27.

GISAXS patterns obtained from (left) OsPA-DS and (right) OsPA-DS-AuNP films measured under low (top) and high (bottom) humidity conditions. Films were spin-coated on Si(100) substrates. Reproduced from [181]. With permission from VCH-Wiley.

Figure 28.

Bioelectrocatalytic response of composite platforms in the presence of increasing amounts of glucose: (a) Au/OsPA-DS/GOx electrode, (b) Au/OsPA-DS-AuNP/GOx electrode. Reproduced from [181]. With permission from VCH-Wiley.

Figure 29.

Representation of the preparation procedure of OsPA-DS-AuNP films in aqueous solvents.

Figure 30.

Representation of j_cat/j₀ ratio as a function of glucose concentration (j_cat = current density observed in presence of glucose and j₀ =current density observed in absence of glucose). Panel (a) depicts the bioelectrocatalytic response of electrodes modified with OsPA-DS-AuNP/GOx nanocomposites and OsPA-DS/GOx assemblies cast from organic solutions. Panel (b) depicts the bioelectrocatalytic response of electrodes modified with OsPA-DS-AuNP/GOx nanocomposites and OsPA-DS/GOx assemblies cast from aqueous solutions. Reproduced from [182]. With permission American Chemical Society.

Figure 31.

Schematic depiction of multicomposite OsPA/DP/OsPA/GOx multilayers.

Figure 32.

GISAXS patterns corresponding to a (OsPA/DP/OsPA/GOx)₅ multilayer self-assembled on a silicon substrate measured at: (a) RH  ~  0% and (b) RH  ~  95%. (c) Out-of-plane scattering profiles from the GISAXS patterns of (OsPA/DP/OsPA/GOx)₅ multilayers obtained under different humidity conditions. Cyclic voltammograms corresponding to: (d) (OsPA/DP/OsPA/GOx)₅ and (e) (OsPA/DP/OsPA/GOx)5/OsPA. The blue trace refers to voltammetric measurements performed in the absence of glucose whereas the red trace refers voltammetric measurements performed in the presence of 50 mm glucose. Supporting electrolyte: 100 mm Tris – HCl buffer  +  0.1 M NaCl (pH 7.4). Reproduced from [183]. With permission Royal Society of Chemistry.