Selective functionalisation of PDMS-based photonic lab on a chip for biosensing

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Analytical Chemistry

Background:

• Poly(dimethylsiloxane) (PDMS) is a common material for lab-on-a-chip devices.
• Selective immobilization of biomolecules is crucial for biosensor development.
• Photonic lab-on-a-chip (PhLoC) platforms require robust surface modification protocols.

Purpose of the Study:

• To compare different surface modification strategies for PDMS.
• To establish a reliable protocol for biomolecule immobilization in PDMS PhLoCs.
• To evaluate the impact of surface treatments on biosensor performance and stability.

Main Methods:

• PDMS surfaces were modified via direct polymer adsorption (polyethylene glycol, polyvinyl alcohol) or chemical oxidation.
• Hydroxyl groups on PDMS were silanized with an aldehyde-terminated silane.
• Biomolecules were covalently attached via amine-aldehyde chemistry.
• Surface characterization included contact angle, XPS, and AFM.
• Biosensors were fabricated and tested for hydrogen peroxide detection using horseradish peroxidase.

Main Results:

• All modification methods enabled covalent attachment of biomolecules.
• Similar analytical performance (linear range 0.1–24.2 µM, LOD ~0.1 µM) was observed across methods.
• Significant differences in device reproducibility and operational stability (up to two months) were found.
• The polyvinyl alcohol (PVA) modification demonstrated superior reproducibility and stability.

Conclusions:

• The PVA-modified PDMS surface is the most suitable for fabricating stable and reproducible biosensor devices.
• This protocol facilitates the integration of biosensors into PDMS-based PhLoC systems.
• The findings contribute to the development of reliable biosensing platforms.