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In this work, we report a novel Langmuir-Blodgett (LB) biosensing platform for the detection of phenolic compounds, using Pyrocatechol as a model analyte. Although LB films have long been explored for polyphenol detection, the present study introduces an innovative hybrid architecture that integrates a lipid matrix (DMPA), a conductive polymer (P3HT), graphene oxide (GO), and laccase into a single, highly organized ultrathin film. This configuration simultaneously enhances film rigidity, reduces surface roughness, and modulates electron-transfer properties in a way not previously reported for LB-based enzymatic sensors. Comprehensive interfacial characterization (surface pressure-area isotherms, dilatational rheology, UV-Vis, AFM) reveals that GO plays a decisive role in promoting compact molecular packing and stabilizing the enzyme-polymer-lipid assembly. As a consequence, the resulting LB films exhibit significantly improved electrochemical performance, including nearly 2-fold higher sensitivity, lower detection limits, and reduced overpotentials compared with films lacking GO. The study also provides mechanistic evidence that the synergy between conductive polymer domains, GO nanosheets, and the immobilized enzyme facilitates more efficient redox cycling of Pyrocatechol. These findings demonstrate that the rational incorporation of GO into LB enzymatic architectures offers a promising route toward next-generation ultrathin biosensors with enhanced analytical performance and structural stability.
1. Surface
pressure–area (A) and Surface compressibility modulus
(B) isotherms for pure DMPA and Mix (blend of DMPA and P3HT) without
or with Laccase and GO.
2. Compression–Expansion
surface pressure–area isotherms
for Mix monolayers without or with laccase and GO. The curves have
been horizontally offset for clearer comparison.
3. Evolution of the absorbance of Langmuir–Blodgett
(LB) films
at selected wavelengths. The connecting lines are provided solely
as visual guides.
5. Voltammograms comparing signal intensity with bare ITO,
1-layer
Mix + Laccase and 1-layer Mix + Laccase + GO, Pyrocatechol 1 ×
10–3 mol/L.
6. (A) Cyclic voltammogram varying the Pyrocatechol
concentration
from 3.33 × 10–7 to 1.15.10 –3 molL–1; (B) Calibration curve, Pyrocatechol concentration x cathodic peak.1-layer Mix + Laccase LB film was used as
working electrode. The calibration curves were obtained from three
independent measurements using separately prepared electrodes separated
in the linear region. The relative deviation for each data point was
below 5%.
7. Using 1-layer Mix + Laccase + Graphene oxide LB film as
working
electrode; (A) cyclic voltammogram varying the Pyrocatechol concentration
from 3.33 × 10–7 to 1.15 × 10 –3 molL–1; (B) calibration curve, Pyrocatechol concentration x cathodic peak. The calibration curves were obtained from
three independent measurements using separately prepared electrodes
separated in the linear region. The relative deviation for each data
point was below 5%.
8. Electrochemical behavior of Pyrocatechol
using a Mix + Laccase
LB film as the working electrode. (A) Cyclic voltammograms recorded
at varying scan rates with Pyrocatechol concentration fixed at 1.15
× 10–3 mol L–1. (B) Plot
of cathodic peak current versus scan rate. (C) Plot of cathodic peak
current versus the square root of the scan rate. (D) Plot of cathodic
peak potential versus the natural logarithm of the scan rate.
9. Electrochemical response of Pyrocatechol using a Mix +
Laccase
+ Graphene Oxide LB film as the working electrode. (A) Cyclic voltammograms
recorded at varying scan rates with Pyrocatechol concentration fixed
at 1.15 × 10–3 mol L–1. (B)
Cathodic peak current as a function of scan rate. (C) Cathodic peak
current as a function of the square root of the scan rate. (D) Cathodic
peak potential as a function of the natural logarithm of the scan
rate.
