Plastic surface-immobilized primers for integrated DNA capture and purification in simplified molecular diagnostics - a proof-of-concept study

Current molecular diagnostic platforms rely on silica-based nucleic acid extraction requiring multiple washbuffers and complex automation, creating cost barriers for resource-limited settings. This proof-of-conceptstudy demonstrates that primer-functionalized plastic surfaces can integrate sample lysis, DNA capture, andpurification into a single-step process. Polycarbonate tubes were surface-engineered using acetone treatmentand UV photo-oxidation to increase carboxyl group density, followed by covalent primer immobilization viabranched polyethyleneimine (BPEI) linkers. Proof-of-concept validation used fluorescence resonance energytransfer (FRET) to confirm DNA capture under both phosphate buffer and chaotropic lysis conditions.Combined acetone and UV treatment increased surface carboxyl density 2-fold (2.02 × 10^−3 to (4.0 × 10^−3nmol/mm^2). BPEI linkers provided 2.6-fold higher oligonucleotide payload compared to linear linkers.FRET validation confirmed specific DNA capture in lysis buffer conditions, achieving 0.125 μ M surfaceboundprimer concentration while reducing process steps from 10 to 3. This proof-of-concept establishestechnical feasibility of replacing silica-based extraction with primer-functionalized surfaces for integratedmolecular diagnostics. The validated surface engineering approach provides a development pathway for simplified,cost-effective diagnostic platforms suitable for resource-limited settings, enabling local manufactureof affordable molecular diagnostic consumables.