VÝVOJ CHYTRÝCH POTENCIOMETRICKÝCH SENZORŮ POTAŽENÝCH VRSTVAMI ODOLNÝMI BIOPASIVACI PRO DETEKCI RANÉHO STÁDIA ZÁNĚTLIVÝCH PROCESŮ KOLEM KLOUBNÍCH NÁHRAD

Importance of the Topic

Implant-associated biofilm infections can rapidly alter the peri-implant microenvironment (pH drop, ROS burst), leading to chronic complications. Real-time detection of these early biochemical changes is crucial for improving implant lifetime and patient outcomes.

Objectives and Study Overview

This study aims to develop two implantable potentiometric sensors:

• An ROS sensor based on a conductive polythiophene-porphyrin-metal film protected by a non-biofouling poly(2-methyl-2-oxazoline) layer.
• A pH sensor based on a polyaniline film on Ti-6Al-4V alloy, similarly coated with poly(2-methyl-2-oxazoline).

The sensors are evaluated for sensitivity, linear range, selectivity and biocompatibility in conditions simulating early inflammatory responses.

Methodology and Instrumentation

• Electropolymerization of 5,10,15,20-tetra(thien-3yl)porphyrin on glassy carbon to form metal–porphyrin complexes (Fe, Cu, Co, Mn).
• Covalent attachment of poly(2-methyl-2-oxazoline) via thienyl end-groups to prevent biofouling.
• Chemical polymerization of polyaniline on Ti-6Al-4V alloy followed by PMeOx coating.
• Potentiometric measurements of H2O2 and pH in phosphate-buffered saline with protein interferences and enzymatic conditions.

Used Instrumentation

• Autolab PGSTAT302N potentiostat for electropolymerization
• 6-channel high-input-impedance voltmeter for potentiometric readings
• Renishaw Via Reflex Raman microscope (514 nm)
• JEOL 6400 scanning electron microscope
• ThermoFisher K-Alpha+ XPS for surface analysis

Main Results and Discussion

• The poly-3TTP-Fe/PMeOx sensor selectively responds to H2O2 with a linear range from 0.05 μM to 10 μM, Nernst slope ~31.7 mV/decade and full reversibility.
• Performance remains stable in the presence of albumin and physiological catalase (slope improves to ~44.4 mV/decade), with no significant response to ClO− at relevant concentrations.
• The PMeOx/PANI@Ti-6Al-4V pH sensor exhibits a Nernstian response of –59.6 mV/pH across pH 5–8, stable standard potential (~559 mV) and excellent reproducibility, even with protein fouling.

Benefits and Practical Applications

• Implantable format enables in situ, real-time monitoring of early infection and inflammation markers.
• Non-biofouling coatings extend sensor stability and accuracy in biological fluids.
• Potential integration with orthopedic implants for continuous postoperative surveillance.

Future Trends and Potential Applications

• Integration into wireless telemetry platforms for remote patient monitoring.
• Expansion to multi-analyte arrays for simultaneous detection of additional biomarkers (e.g., metal ions, cytokines).
• Translation towards clinical trials and regulatory approval of smart implant systems.

Conclusion

The combination of metal–porphyrin conductive films and non-biofouling polymer layers yields robust potentiometric sensors for early detection of inflammatory ROS and pH shifts around orthopedic implants. These platforms demonstrate sensitive, selective and reversible responses in relevant biological conditions, paving the way for next-generation smart implants.

Reference

• Ivanko I., Tomšík E., Hrubý M. Sens. Actuators B 363, 131827 (2022)
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• Balasubramanian P. et al. ACS Appl. Mater. Interfaces 10, 43543 (2018)
• Manavalan S. et al. Nanoscale 12, 5961 (2020)
• Li P. et al. Anal. Chem. 92, 12987 (2020)
• Tan H. et al. Anal. Chem. 92, 3447 (2020)
• Tomšík E. et al. Adv. Mater. Interfaces 10, 2201878 (2022)