Architecting Dandelion-Like Silica Nanotube Superparticles Via Hierarchical Emulsion-Mediated Sol-Gel Synthesis.

The assembly of nanotubes into 3D superstructures that combine high active-site density with efficient mass transport remains a significant challenge. Conventional silica nanotubes tend to tangle and form disordered aggregates, burying functional interfaces and limiting practical applications. Herein, we introduce a hierarchical emulsion-mediated sol-gel strategy for the direct construction of dandelion-like silica nanotube superparticles (D-SiO2 NTS) composed of radially aligned nanotube bundles. In a biphasic pentanol-water system, organosilane-rich droplets and surface-localized water-enriched nanodroplets create interfacial microdomains that confine the hydrolysis and co-condensation of tetraethyl orthosilicate and (3-mercaptopropyl)trimethoxysilane. This interfacial confinement disfavors lateral deposition and biases growth toward outward anisotropic extension, ultimately yielding dandelion-like hollow microspheres covered with radially arranged silica nanotubes. The resulting open-framework architecture provides highly accessible pore channels and abundant thiol groups for post-functionalization. As a proof of concept, L-cysteine-functionalized D-SiO2 NTS are immobilized in a glass micropipette to create a confined coordination interface for ionic-current-based Cu2+ sensing. The sensor exhibits a broad detection range (0.1 µM to 100 mM), a low detection limit (0.047 µM), excellent selectivity, and stable performance over nine days. By linking hierarchical interfacial organization to anisotropic hollow growth, this work provides a chemical design principle for directly constructing accessible 3D silica nanotube architectures.