biostudies-literatureUnknown10(47)Aphrham SPrecise localization of biomarkers within the sensing area of biosensors is crucial for enhancing performance and minimizing analyte loss to nonsensing regions. Commercial material-selective coatings enable site-specific biofunctionalization but are typically constrained by limited reactive chemistries, reducing their versatility and controllability. We present a selective coating strategy based on a poly-l-lysine (PLL) scaffold that retains the material-selective properties of a commercial carboxylic acid (COOH)-based coating for a Si<sub>3</sub>N<sub>4</sub> waveguide with a poly-(ethylene glycol) (PEG)-covered SiO<sub>2</sub> surrounding while enabling modular surface functionalization. The PLL scaffold was functionalized with controlled grafting densities of oligo-(ethylene glycol) (OEACS omega57674-57683https://www.ebi.ac.uk/biostudies/studies/S-EPMC12676348biostudies-literatureMaterial-Selective Deposition of Reactive Group-Functionalized Poly‑l‑lysine for DNA Sensing at Optical Waveguides.PMC12676348Huskens JAphrham SVerheijden MfalseMaterial-Selective Deposition of Reactive Group-Functionalized Poly‑l‑lysine for DNA Sensing at Optical Waveguides.Precise localization of biomarkers within the sensing area of biosensors is crucial for enhancing performance and minimizing analyte loss to nonsensing regions. Commercial material-selective coatings enable site-specific biofunctionalization but are typically constrained by limited reactive chemistries, reducing their versatility and controllability. We present a selective coating strategy based on a poly-l-lysine (PLL) scaffold that retains the material-selective properties of a commercial carboxylic acid (COOH)-based coating for a Si<sub>3</sub>N<sub>4</sub> waveguide with a poly-(ethylene glycol) (PEG)-covered SiO<sub>2</sub> surrounding while enabling modular surface functionalization. The PLL scaffold was functionalized with controlled grafting densities of oligo-(ethylene glycol) (OE2025-01-01T00:00:00Z2025 Dec2026-06-05T23:31:13.041Z2026-05-23T03:13:47.732ZS-EPMC126763484135807510.1021/acsomega.5c09098