A semi-quantitative rapid multi-range gradient lateral flow immunoassay for procalcitonin.

Area of Science:

• Biomedical Engineering
• Immunodiagnostics
• Clinical Chemistry

Background:

• Procalcitonin (PCT) is a crucial biomarker for diagnosing sepsis and bacterial infections.
• Existing diagnostic methods may lack the speed or semi-quantitative capability needed for rapid clinical assessment.
• Lateral flow immunoassays (LFIA) offer potential for rapid point-of-care diagnostics.

Purpose of the Study:

• To develop a rapid, semi-quantitative gradient lateral flow immunoassay (LFIA) for procalcitonin (PCT).
• To establish a visual method for determining PCT concentration ranges relevant to sepsis diagnosis.
• To evaluate the performance of the developed LFIA against established methods like ELISA.

Main Methods:

• A gradient LFIA was designed by immobilizing antibodies at increasing concentrations on test strips.
• Two types of gold nanoparticles (spherical and popcorn-like) were used as labels.
• Visual interpretation of colored test lines correlated to specific PCT concentration ranges (˂0.25 to ≥10 ng·mL⁻¹).

Main Results:

• The gradient LFIA successfully provided semi-quantitative analysis of PCT levels across defined ranges.
• Comparison with ELISA (n=82) showed high sensitivity (87.5%) and specificity (92.3%) at key PCT thresholds.
• The assay demonstrated reliable performance for identifying clinically relevant PCT concentration ranges.

Conclusions:

• The developed multi-range gradient LFIA is a promising tool for the early diagnosis of sepsis and severe bacterial infections.
• This visual, semi-quantitative method offers a practical approach for rapid PCT assessment.
• The gradient LFIA technology has broad applicability for other analytes in various LFIA-based diagnostic systems.