Sensitive and efficient bioanalytical detection is an ongoing challenge. The possibility of physically and chemically manufacturing nano features on solid supports, as well as that of precisely engineering the properties at the interface, has paved the way for a new era of surface-based biosensing devices. DNA recognition platforms have attracted growing interest due to their potential use in drug formulations, environmental monitoring and biomedical applications. The high intrinsic specificity and sensitivity of DNA biosensors can drastically improve the diagnosis and therapy efficacy of genetic diseases. However, the characteristics of the biorecognition interface (e.g. probe density, layer architecture, surrounding environment, type of substrate) represent crucial factors for the hybridization process and the high sensitivity of DNA biosensors [1]. Signal amplification strategies are routinely exploited to assess reliable assays with lower limits of detection, representing opportunities for obtaining more efficient (bio)sensing platforms [2]. The possibility of tuning the chemical moieties and their density plays a fundamental role in targeting surface-confined molecular structures and their functionalities at macro and nanoscale levels. Such interfacial control is crucial for engineered coating formation and biorecognition purposes, where the type and density of ligands/receptors at the surface affect the overall binding affinities and the device performance [3]. Together with the well-established self-assembled monolayers, a surface modification approach based on polyelectrolytes has gained importance to provide desired characteristics at the substrate interface. References [1] Di Iorio, D. et al. RSC Adv., 2019, 9, 35608-35613. [2] Marti, A. et al. Nanomaterials. 2022, 12(2), 242. [3] Ettabib, M. A. et al. ACS Sens., 2021, 6, 2025–2045. Acknowledgements The authors acknowledge support from financial support by the MESA+ Institute, University of Twente, grant “Early cancer diagnostics” and by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/R011230/1, “Flexible Raman biosensing platform for low-cost health diagnostics”