OligoA-tailed DNA for dense functionalization of gold nanoparticles and nanorods in minutes without thiol-modification: unlocking cross-disciplinary applications†

DNA-functionalized gold nanoparticles (DNA–AuNPs) and nanorods (DNA–AuNRs) have emerged as key yet versatile biomaterials for applications in biosensing, diagnostics and programmable assembly. The high cost and sometimes complex procedures of functionalization of DNA onto AuNPs and AuNRs via the Au−thiol interaction may have set a threshold for its expanded application by researchers of diverse fields. Although oligoA-tailed DNA has been introduced as an alternative to thiolated DNA, its extended use has been largely confined to spherical nanoparticles with suboptimal functionalization density. Here we show a rapid and efficient method for high-density functionalization of both AuNPs and AuNRs using oligoA-tailed DNA via butanol dehydration, with the length of oligoA as short as A₂. By preventing secondary structure formation at an elevated temperature, our results demonstrate significantly enhanced DNA adsorption, further allowing for functionalization of a random sequence onto the AuNPs. This yields stable DNA–nanoparticle conjugates with superior stability and durability, suitable for in situ naked-eye loop-mediated isothermal amplification (LAMP) assay of bacterial pathogens and stimuli-responsive self-assembly. This study overcomes long-standing barriers in rapid, simple and low-cost preparation of DNA–AuNPs and DNA–AuNRs, paving the way for cross-disciplinary applications in diverse fields that were previously siloed and beyond.