Structurally Engineered Yolk-Shell Mesoporous Silica Rods with Liquid and Nanoparticle Cargo

Abstract

Yolk-shell-structured nanomaterials provide a versatile platform for encapsulating both solid and liquid substances, making them advanced alternatives to hollow materials. While most studies focus on spherical yolk-shell structures, this study pioneers the synthesis of rod-shaped alternatives. Uniform silica rods (SR) were synthesized using silica nanoparticles as growth nuclei and employed as sacrificial templates to fabricate hollow mesoporous and yolk-shell-structured silica rods (HMSR and YSSR, respectively). Dual-fluorescent silica rods were developed by fluorescently labeling the silica shell and encapsulating fluorescent oil within the hollow core, demonstrating their potential as delivery carriers for lipophilic drugs. YSSR was engineered using magnetite nanoparticles (Fe₃O₄) as growth seeds and modifying the silica surface to attach gold nanospheres (AuNS) via electrostatic interactions. By integrating these approaches, multifunctional YSSR encapsulating both Fe₃O₄ and AuNS was fabricated. YSSR exhibits unique functionalities, such as paramagnetism and photothermal effects, depending on the encapsulated nanoparticles. These universal synthesis strategies for HMSR and YSSR provide a robust platform for encapsulating diverse substances, paving the way for new application opportunities.