Sensitive fluorescence-based detection of CA15-3 using femtosecond laser and four-parameter logistic regression: a promising tool for early breast cancer diagnosis

The carbohydrate antigen 15 − 3 (CA 15 − 3) is the most commonly used serum biomarker for breast cancer, playing a crucial role in detecting metastases and monitoring patients disease progression. Fluorescence methods, such as laser-induced fluorescence (LIF), offer high sensitivity and selectivity, making them suitable for point-of-care analysis. LIF, a technique, is being explored for its potential in detecting tumor biomarkers, which could be used in early cancer diagnosis. In the current study, LIF spectra of CA15-3 tumor biomarker were recorded using a femtosecond laser system over an excitation range of 360–420 nm. The strongest fluorescence response was observed at 360 nm, yielding an emission peak centered at 489 nm. At this optimal excitation wavelength, a series of CA15-3 concentrations were analyzed, revealing a concentration-dependent variation in fluorescence peak intensity. A nonlinear four-parameter logistic (4PL) model, together with the limit of detection (LOD), was applied to fluorescence peak intensity data at various concentrations to determine the analytical sensitivity of fluorescence-based CA15-3 detection. The results showed that the lowest concentration was around 12.75 U/mL. Thus, the latter value is significantly below the clinical decision threshold of 30 U/mL for CA15-3. Interestingly, the system exhibits high analytical sensitivity and robustness, enabling the detection of clinically relevant biomarker concentrations at early stages of disease progression. This early diagnostic capability is crucial for timely clinical decision-making and improved patient outcomes. Collectively, these findings suggest the system as a promising platform for future clinical applications and translational research.