A Smartphone-based Diffusometric Immunoassay for Detecting C-Reactive Protein.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Nanotechnology

Background:

• C-reactive protein (CRP) is a key biomarker for inflammation and infection.
• Accurate and accessible CRP quantification methods are crucial for clinical diagnostics.
• Current methods may require specialized equipment or complex laboratory procedures.

Purpose of the Study:

• To develop a portable and cost-effective smartphone-based diffusometry system for CRP analysis.
• To utilize fluorescence correlation spectrometric (FCS) analysis for measuring nanobead diffusion.
• To establish a correlation between nanobead diffusion coefficients and CRP concentrations.

Main Methods:

• A smartphone with a fluorescence microscopic add-on system was used to image 300 nm fluorescent beads.
• Sequential images were captured and analyzed using FCS to determine the diffusion coefficient of nanobeads.
• Anti-CRP-coated nanobeads were suspended in samples with varying CRP concentrations.
• The diffusion coefficients of anti-CRP-coated nanobeads were measured after a 10-minute reaction time.

Main Results:

• Smartphone-based diffusometry successfully measured the diffusion coefficient of nanobeads.
• A decrease in diffusion coefficient was observed with increasing CRP concentration.
• A linear sensing range for CRP was established between 1 and 8 µg/mL.

Conclusions:

• Smartphone-based diffusometry is a viable method for CRP concentration analysis.
• The developed system offers a portable and potentially low-cost diagnostic approach.
• This technology could facilitate point-of-care CRP testing.