Long-period grating optical fiber sensor for IgG-type monoclonal protein measurement.

Measuring monoclonal proteins (M-proteins) plays an important role in the diagnosis and monitoring of plasma cell dyscrasias. Measurements of M-proteins are mostly conducted by electrophoresis, which requires complex sample processing and takes several hours to obtain a result. In this work, IgG kappa M-protein (IgGκ) and IgG lambda M-protein (IgGλ) sensors are developed based on a long-period grating optical fiber sensor. The IgGκ sensor has a limit of detection (LoD) of 2.78 μg/mL and a selectivity of 9.73. The IgGλ sensor has an LoD of 2.75 μg/mL and a selectivity of 27.9. The sensor has sufficient sensitivity to detect clinically relevant M-protein levels, highlighting its significant potential as a rapid, easy-to-use point-of-care testing (POCT) platform with strong clinical applicability in healthcare.