Surface‑Engineered Primer Immobilization Enables Simplified and Affordable Nucleic‑Acid Capture for Molecular Diagnostics in Sub‑Saharan Africa

Molecular diagnostic (MDx) technologies remain prohibitively expensive for many laboratories in sub-Saharan Africa. this is because current platforms rely on silica-based extraction processes that require multiple wash buffers, magnetic components, and ethanol handling. This study presents a simplified, silica-free approach that uses functionalized polymer surfaces for nucleic-acid capture. Polycarbonate was selected as a model sub-strate based on its thermal stability and innate carbonate groups, which were chemically and optically mod-ified by low-cost acetone and ultraviolet (UV) pretreatments to generate surface carboxyl (–COOH) groups. Quantification using toluidine blue-O dye revealed a twofold increase in COOH density after combined ace-tone–UV treatment, enabling efficient covalent attachment of primers through branched polyethyleneimine linkers. Comparative fluorescence assays confirmed that BPEI-linked surfaces carried approximately 2.6 times more oligonucleotides than ethylenediamine-linked surfaces. Hybridization experiments using fluores-cence resonance energy transfer (FRET) verified specific DNA capture under both phosphate and chaotropic lysis conditions, demonstrating compatibility with standard sample buffers. Although amplification directly from immobilized primers was not performed, hybridization and payload analyses showed that the sur-face contained sufficient primer density for enzymatic reactions. The described process replaces complex silica-based extraction with a single solid-phase capture step, offering a simple, inexpensive, and locally manufacturable pathway toward affordable molecular diagnostics in resource-limited settings.