Microfluidic continuous flow synthesis of functional hollow spherical silica with hierarchical sponge-like large porous shell

Abstract

Microfluidics brings unique opportunities for engineering micro-/nanomaterials with wellcontrolled physicochemical properties. Herein, using a miniaturized multi-run spiral-shaped microreactor, we develop a flow synthesis strategy to continuously produce hollow spherical silica (HSS) with hierarchical sponge-like pore sizes ranging from several nanometers to over one hundred nanometers. The formation of HSS is realized by mixing two reactant flows, one containing cetyltrimethylammonium bromide (CTAB) and diluted ammonia and the other 1,3,5trimethylbenzene (TMB) and diluted tetraethyl orthosilicate (TEOS), at a flow rate as high as 5 mL/min. The effect of the reactant concentration and the flow rate on the structural change of the resultant materials is examined. Functional small-sized nanoparticles (magnetic nanoparticle, quantum dot, and silver nanoparticle) can be separately assembled into HSS and high molecular weight protein (bovine serum albumin) can be successfully loaded into HSS and delivered into cancer cells afterward, making them promising in the fields of separation and purification, bioimaging, catalysis, and theranostics.

An Update on Mesoporous Silica Nanoparticle Applications in Nanomedicine

“…Furthermore, Hao et al developed a novel microfluidic synthesis strategy with well-controlled physicochemical properties and used it for developing hollow spherical silica (HSS). The HSS was then assembled with different functional small-sized NPs, including QDs, silver nanoparticles, and magnetic nanoparticles, to simultaneously acquire specific magnetic, fluorescent, or catalytic properties [ 255 ]. This technology provides the intracellular and cell-specific delivery of imaging agents which are expected to contribute to clinical applications in the future.…”

Microfluidics for ZnO micro-/nanomaterials development: rational design, controllable synthesis, and on-chip bioapplications

“…The past decade has witnessed considerable progress in the development of microfluidic systems for controllable synthesis and applications of ZnO micro-/nanomaterials. Owing to their many unique and attractive features (especially flexible spatiotemporal control, high integration capability, and low sample consumption), [106][107][108][109][110][111][112][113] microfluidic devices fabricated with PDMS or glass capillaries significantly advance the rational design and applicability of functional materials. To date, ZnO structures with different sizes, shapes, and compositions have been developed for applications in the biomedical fields.…”

Synthesis and Surface Engineering of Inorganic Nanomaterials Based on Microfluidic Technology

“…Besides, mesoporous silica nanoparticles (MSNs) with tunable structures and morphologies have been synthesized by using microfluidic technology [ 26 , 27 , 28 , 29 , 30 , 31 , 71 ]. Zhang and coworkers synthesized MSNs with different morphologies by injecting liquid phases containing silica precursors and surfactants into two separate inlets in a spiral microfluidic chip ( Figure 1 d) [ 26 ].…”