At-line bioprocess monitoring by immunoassay with rotationally controlled serial siphoning and integrated supercritical angle fluorescence optics

• Sample-to-answer microfluidic lab-on-a-disc device for at-line bioprocess monitoring.
• Centrifugally integrated and automated reagent delivery by serial-siphon valves.
• Supercritical angle fluorescence optics embedded on centrifugal platform.
• Development of fluorescence-linked-immunosorbent assay on human immunoglobulin G.
• Bioprocess samples from industrial reactor determined on the prototype system.

In this paper we report a centrifugal microfluidic “lab-on-a-disc” system for at-line monitoring of human immunoglobulin G (hIgG) in a typical bioprocess environment. The novelty of this device is the combination of a heterogeneous sandwich immunoassay on a serial siphon-enabled microfluidic disc with automated sequential reagent delivery and surface-confined supercritical angle fluorescence (SAF)-based detection. The device, which is compact, easy-to-use and inexpensive, enables rapid detection of hIgG from a bioprocess sample. This was achieved with, an injection moulded SAF lens that was functionalized with aminopropyltriethoxysilane (APTES) using plasma enhanced chemical vapour deposition (PECVD) for the immobilization of protein A, and a hybrid integration with a microfluidic disc substrate. Advanced flow control, including the time-sequenced release of on-board liquid reagents, was implemented by serial siphoning with ancillary capillary stops. The concentration of surfactant in each assay reagent was optimized to ensure proper functioning of the siphon-based flow control. The entire automated microfluidic assay process is completed in less than 30 min. The developed prototype system was used to accurately measure industrial bioprocess samples that contained 10 mg mL−1 of hIgG.

A serial siphon based centrifugal microfluidic platform for the quantitative at-line monitoring of human immunoglobulin G (hIgG) in typical industrial bioprocess samples using a prototype optical SAF detection system.Figure optionsDownload as PowerPoint slide