Acoustic Levitation Synthesis of Ultrahigh‐Density Spherical Nucleic Acid Architectures for Specific SERS Analysis

Abstract

Controllably regulating the electrostatic bilayer of nanogold colloids is a significant premise for synthesizing spherical nucleic acid (SNA) and building ordered plasmonic architectures. We develop a facile acoustic levitation reactor to universally synthesize SNAs with an ultra‐high density of DNA strands. Results reveal a new mechanism of DNA grafting via acoustic wave that can reconfigure the ligands on colloidal surfaces. The acoustic levitation reactor enables substrate‐free three‐dimentional (3D) spatial assembly of SNAs with controllable interparticle nanogaps through regulating DNA lengths. This kind of architecture may overcome the plasmonic enhancement limits by blocking electron tunneling and breaking electrostatic shielding in dried aggregations. Finite element simulations support the architecture with 3D spatial plasmonic hotspot matrix, and its ultrahigh surface‐enhanced Raman scattering (SERS) capability is evidenced by in‐situ untargeted tracking of biomolecular events during photothermal stimulation (PTS)‐induced cell death process. For biomarker diagnosis, the conjugation of ATP aptamer onto SNAs enables in‐situ targeted tracking of ATP during PTS‐induced cell death process. Particularly, the CD71 receptor and integrin α3β1 protein on PL45 cell could be well distinguished by label‐free SERS fingerprints when using specific XQ‐2d and DML‐7 aptamers, respectively. Our current acoustic levitation reactor promises great potentials in biochemical synthesis and sensing in future.