Bovine Serum Albumin Enhances the Quantitative Performance of Polydimethylsiloxane-Based Chamber Digital PCR by Suppressing Surface Adsorption

Polydimethylsiloxane (PDMS) surfaces are highly hydrophobic, and non-specific biomolecule adsorption is a well-known limitation in microfluidic PCR systems. Flow-based microfluidic PCR has been extensively studied, but the impact of surface adsorption on quantitative performance in closed-chamber digital PCR (dPCR) platforms remains poorly characterized. This adsorption may reduce the effective concentrations of key reaction components and compromise quantification accuracy. Therefore, in this study, we evaluated two approaches to prevent molecular adsorption in PDMS-based cdPCR systems: (i) the addition of chemical additives to the PCR reaction mixture and (ii) the incorporation of hydrophilizing agents into PDMS, with solution-phase additives proving more effective in this system. We investigated the effects of the reaction additives bovine serum albumin (BSA), Blocking One-P, and dextran on DNA quantification using a PDMS-based dPCR chip. A single-concentration comparison showed that 1.1% BSA produced the highest average DNA copy number (0.091 ± 0.010 copies/well), compared to the no-additive condition (0.039 ± 0.010 copies/well), corresponding to an approximately 2.3-fold increase, whereas Blocking One-P and dextran had no substantial effects. Dilution series experiments were then conducted under BSA-added and BSA-free conditions using plasmid DNA and cDNA derived from HSC4 cells as templates. In both cases, BSA improved quantitative linearity, as reflected by the increased slopes and coefficients of determination.