Automated renewable label-free optical sensor for quantification of therapeutic monoclonal antibodies

Biopharmaceuticals, particularly monoclonal antibodies (mAbs), are essential for treating cancer, autoimmune disorders, and infectious diseases. These complex biologics require precise manufacturing and regulatory strategies. Process analytical technology enables the analysis and control of biopharmaceuticals' manufacturing processes through timely measurements of critical quality and performance attributes, aiming to ensure product quality. The production of high-quality therapeutic mAbs becomes challenging due to the high cost of analytical methods. In this work, a miniaturized approach based on UV-Vis micro-bead injection spectroscopy within a lab-on-valve platform is proposed for the quantitative, label-free determination of therapeutic mAbs, specifically rituximab (RTX), in cell culture supernatants. The sensor is automatically assembled, through computer-controlled, fluidic manipulation of Concanavalin A-Sepharose beads. These beads enable recognition of glycosylated mAbs, facilitating on-column label free optical density measurement at 280 nm. Beads are discarded after each determination, avoiding carrying-over between samples. Key parameters were optimized to enhance sensitivity and repeatability of RTX detection. The method demonstrated good linearity (0.25-1.50 mg mL^-1, R > 0.9970), with a limit of detection of 0.11 mg mL^-1. Each determination required 8 min of total analysis and 0.12 mg of sorbent. When applied to surrogate cell culture supernatants, the μ-BIS-LOV sensor exhibited consistent recovery rates across different dilutions, confirming its suitability for bioprocess monitoring and quality control of biopharmaceuticals. This method offers a simplified, cost-effective alternative to traditional analytical techniques, reducing reagent consumption and eliminating the need for secondary antibodies, offering an efficient solution for quality control in biopharmaceutical production.