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 <i>via</i> 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 <i>via</i> 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 <i>in situ</i> 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.