Rapid Construction of Thiolated DNA-AuNP Conjugates via PolyA Blocking for Precise Control of Surface Functionalization

DNA-gold nanoparticle (DNA-AuNP) conjugates were widely applied in biosensing depending on their diverse photophysical and biochemical characteristics. Albeit advanced, conventional methods relying on direct thiolated-DNA adsorption often suffer from poor control over DNA conformation and loading on gold surfaces. In particular, the rigid and irreversible nature of Au-S bonding makes it difficult to finely tune surface coverage, leading to heterogeneous interfacial structures. Herein, we present a rapid and tunable strategy for constructing DNA-AuNP conjugates by introducing polyA blockers to modulate the accessibility of thiolated strands. By integrating thermal-drying and freezing approaches, polyA-mediated DNA-AuNP assemblies can be prepared within minutes. Systematic comparison of polyA lengths revealed that A5 provides the most favorable interfacial environment, yielding the highest hybridization efficiency with complementary strands and supporting its use in the fast thermal-drying assembly workflow. Furthermore, by adjusting the surface density of A5, we achieved precise regulation of thiolated DNA loading on AuNPs, enabling adjustable interfacial architecture. This strategy not only enables rapid construction of DNA-AuNP conjugates but also provides an effective and versatile approach for finely tuning the interfacial architecture of thiolated-DNA-modified nanostructures, thereby establishing a robust foundation for downstream applications such as aptamer engineering and biosensing.