Monolith-modified cellulose paper for biochemical sensing applications
In this study, we developed a microfluidic paper-based analytical device (μPAD) modified with a poly(GMA-co-EDMA) monolith for rapid tuberculosis detection. GMA-co-EDMA successfully enhanced the affinity between the paper substrate and pipetted biomolecules through covalent interactions between the opened epoxy ring and functional groups such as thiol and amino groups on the biomolecules. After synthesizing monoliths onto cellulose paper, fabrication parameters such as wax melting time duration and temperature were tested. We determined the optimized parameters for fabricating a surface-modified microfluidic-based analytical device (sPAD) after observing the modified paper surface with scanning electron microscopy (SEM) images, contact angle measurement, and colorimetric immunoassays. The optimized enzymatic reaction is 5 minutes after testing IgG from human serum (HIgG) on the sPAD. Finally, tuberculin purified protein derivative (PPD) as an analyte can be detected within 30 minutes with a detection limit of less than 0.11 ng mL−1. These results indicate that our device possesses the potential for rapid and sensitive tuberculosis detection in resource-limited settings.