Paperfluidic devices with a selective molecularly imprinted polymer surface for instrumentation-free distance-based detection of protein biomarkers.

• Paperfluidic devices (μPADs) combined with distance-based detection (DμPADs). • Molecularly imprinted polymer (MIP) used to enhance selectivity in MIP-DμPADs. • Polydopamine MIP polymerised from dopamine coated onto the DμPAD paper substrate. • MIP-DμPADs investigated for the determination of chymotrypsinogen in urine. • Fabricated with low-cost instrumentation, the analysis is instrumentation-free. Microfluidic paper-based analytical devices (μPADs) offer the advantages of simplicity, extremely low costs, robustness, and miniaturisation, synergistically supporting portability and point-of-care (POC) analysis. When μPADs are combined with distance-based detection in DμPADs, they uniquely enable a quantitative analytical platform that is truly instrumentation-free (naked-eye readout), or at least, does not require any specialised scientific instrumentation (only mobile phone camera). However, a significant drawback of DμPADs is their limited selectivity. In this work, we present for the first time molecularly imprinted polymer (MIP) as a selectivity-enhancing element in MIP-modified DμPADs (MIP-DμPADs). Herein, a layer of polydopamine MIP was coated onto the paper substrate of a DμPAD, in a simple process using dopamine as the monomer deposited onto the paper matrix in the migration-detection zone of the DμPAD, and polymerised in a rapid low cost procedure in the presence of oxygen under alkaline conditions. The polydopamine MIP-DμPAD was then systematically investigated for the selective determination of chymotrypsinogen (chymo) as a model protein biomarker in urine, within the linear concentration range 2.4–29.2 μM (R2 = 0,9903) with corresponding relative standard deviations ranging from 2% to 11 % and LOD =3.5 μM and LOQ =11.8 μM. The here presented analytical concept based on MIP-DμPADs has a potential in POC diagnostics, because of the combination of low cost automated fabrication, the rapid quantitative near to instrumentation-free analysis, and selectivity through the use of MIPs as a synthetic, more stable, cheaper and easily prepared alternative to bio-macromolecules. [ABSTRACT FROM AUTHOR]