Labeling on a chip of cellular fibronectin and matrix metallo-peptidase-9 in human serum

Abstract

We present a microfluidic chip for protein labeling in the human serum-based matrix. Serum is a complex sample matrix that contains a variety of proteins, and a matrix used in many clinical tests. In this work, the device performance was tested using commercial serum samples from healthy donors (commercial) spiked with the following target proteins: cellular fibronectin (c-Fn) and matrix metallopeptidase 9 (MMP9).The microfluidic molds were fabricated using micro milling on acrylic and using stereolithography (SLA) three-dimensional (3D) printing for an alternative method and comparison. Simple quality control was performed for both fabrication mold meth-ods to inspect the channel height of the chip that plays a critical role in the labeling process. The fabricated microfluidic chip shows good reproducibility and repeatability of the performance for the optimized channel height of 150 µm. The spiked protein of cellular fibronectin (c-Fn) and matrix metallopeptidase 9 (MMP9) in the human serum-based matrix were successfully labeled by functionalized magnetic nanoparticles (MNPs). The biomarker labeling occurring in serum was compared using a simple matrix sample: phosphate buffer. The measured signals obtained by using a magnetoresistive (MR) biochip platform showed that the labeling using the proposed microfluidic chip is in good agreement for both matrixes, i.e., the analytical performance (sensitivity) obtained with serum, near the relevant cutoff values, is within the uncertainty of the measurements obtained with a simple and more controlled matrix: phosphate buffer. This finding is promising for stroke patient stratification where these biomarkers are found at high concentrations in serum.