A label-free sensing method for phosphopeptides using two-layer gold nanoparticle-based localized surface plasma...

Area of Science:

• Nanotechnology
• Biomedical Sensing
• Surface Chemistry

Background:

• Localized Surface Plasmon Resonance (LSPR) is sensitive to changes in the local dielectric environment.
• Near-infrared (NIR) LSPR offers enhanced sensitivity compared to visible light LSPR.
• Phosphopeptides play crucial roles in cellular signaling and disease pathogenesis.

Purpose of the Study:

• To develop a novel LSPR sensing substrate for sensitive phosphopeptide detection.
• To utilize near-infrared (NIR) absorption properties for improved sensing capabilities.
• To demonstrate the substrate's utility in detecting cancer-associated phosphopeptides in complex biological samples.

Main Methods:

• Fabrication of a layer-by-layer self-assembled gold nanoparticle (Au NP) substrate on glass slides.
• Modification of the substrate with a thin titania film (TiO(2)-Glass@Au NPs) for phosphopeptide capture.
• Utilizing absorption spectrophotometry for LSPR-based detection.
• Validation using tryptic digest of α-casein and analysis of phosphorylated fibrinopeptide A in human serum via MALDI-MS.

Main Results:

• The fabricated TiO(2)-Glass@Au NPs substrate exhibited a distinct LSPR absorption band in the NIR region due to inter-particle dipole-dipole interactions.
• The substrate demonstrated enhanced sensitivity for phosphopeptide detection compared to conventional methods.
• Successful detection of phosphorylated fibrinopeptide A directly from human serum samples was achieved, highlighting clinical relevance.

Conclusions:

• The developed LSPR sensing substrate offers a sensitive and straightforward platform for phosphopeptide detection in the NIR region.
• This approach holds significant potential for early cancer risk factor screening and biomarker discovery in clinical diagnostics.
• The TiO(2)-functionalized Au NP substrate represents a promising advancement in nanobiosensing technologies.