Layer-by-layer generation of PEG-based regenerable immunosensing surfaces for small-sized analytes.

Area of Science:

• Surface chemistry and materials science
• Biotechnology and biosensing
• Analytical chemistry

Background:

• Small molecules (haptens) are crucial targets in competitive immunoassays.
• Developing robust and reusable surfaces for hapten immobilization is essential for biosensor development.
• Existing methods may lack reproducibility or universality for diverse haptens.

Purpose of the Study:

• To present a detailed strategy for preparing polyethylene glycol (PEG) coated silica surfaces for hapten immobilization.
• To characterize the functionalization process and the resulting surface properties.
• To validate the utility of these surfaces in competitive biosensing applications.

Main Methods:

• Surface functionalization using 3-glycidyloxypropyltrimethoxysilane (GOPTS) and diamino-poly(ethylene glycol) (DAPEG) on silica substrates.
• Characterization via atomic force microscopy (AFM), water contact angle, FT-IR, and X-ray photoelectron spectroscopy (XPS).
• Validation using quartz crystal microbalance with dissipation (QCM-D) and automated flow-through immunoassay with chemiluminescence (CL) read-out.

Main Results:

• Successful grafting of molecular layers confirmed by multiple characterization techniques, indicating homogeneous monolayers.
• Demonstrated antibody recognition and reversibility using QCM-D and CL-based immunoassays.
• The functionalized surfaces exhibited stability over 14 days in aqueous solution without performance decrease.

Conclusions:

• The presented surface functionalization strategy provides a reproducible and reusable universal platform for hapten biosensors.
• This method enables the development of sensitive and stable biosensing devices for pharmaceuticals, peptides, and other small molecules.
• The validated approach offers significant potential for future advancements in diagnostic and analytical tools.