Enhancing the Exploitation of Functional Nanomaterials through Spatial Confinement: The Case of Inorganic Submicrometer Capsules

Abstract

Hollow inorganic nanostructures have attracted much interest in the last few years due to their many applications in different areas of science and technology. In this Feature Article, we overview part of our current work concerning the collective use of plasmonic and magnetic nanoparticles located in voided nanostructures and explore the more specific operational issues that should be taken into account in the design of inorganic nanocapsules. Along these lines, we focus our attention on the applications of silica-based submicrometer capsules aiming to stress the importance of creating nanocavities in order to further exploit the great potential of these functional nanomaterials. Additionally, we will examine some of the recent research on this topic and try to establish a perspective for future developments in this area.

Transferrin‐Coated Nanodiamond–Drug Conjugates for Milliwatt Photothermal Applications

“…Comparing absolute ICG concentrations, the magnitude difference in temperature profile produced by ICG‐Tf‐fND suggests that there is an enhancement for the loaded ICG over that of molecularly free ICG. This amplified photothermal effect by confinement was also characteristically observed in hollow inorganic nanoparticles and plasmonic nanoparticle clusters . The strong interaction of ICG with Tf‐fND was demonstrated by the negligible release of ICG (<5%) from ICG‐Tf‐fND when incubated in cell media for 24 h (Figure S10, Supporting Information).…”

Engineering microencapsulation of highly catalytic gold nanoclusters for an extreme thermal stability

“…37 The benefits of creating nanocavities in order to further exploit the potential of functional metal nanomaterials have been recently reviewed by our group. 38 In this scenario, the stability of the gold nanoclusters has been assessed through the synthesis and application of the hollow counterparts of the SiO 2 /0.8-1.2 nm AuNP/SiO 2 nanocomposites. With this aim, polystyrene (PS) beads were used as sacrificial templates and coated with a microporous silica layer (∼1 nm pore size) onto which 0.8-1.2 nm AuNPs were subsequently deposited.…”

Confined Nucleation and Growth of PdO Nanocrystals in a Seed-Free Solution inside Hollow Nanoreactor

“…In view of this, this study reports an approach for restricting the volume of medium available for NC formation in the solution inside a hollow nanoparticle cavity of a few tens of nanometers in size, allowing detailed examination of NC nucleation from a precursor solution. Since the reports on the growth of metal NCs inside of organic polymer-based nanocapsules of submicrometer sizes, , attempts to cultivate metal NCs inside the nanosized mold were made by using hollow silica nanoparticle as a nanoreactor for templating the NC growth inside the cavity. − Confinement of the reaction within the hollow nanoparticle interior might be an effective method for the systematic investigation and control of NC formation steps in an isolated and consistent environment in the absence of interference from neighboring reactions. − Very recently, introduction of a Au NC-containing hollow silica nanoreactor into a metal-growing suspension allowed us to monitor the growth of Ag, Pt, and Ni NCs on seed NCs preinserted inside the cavity. − Nonetheless, the confinement of NC formation to the interior of a nanoreactor not containing any seed NCs has yet to be achieved because making nucleation inside the cavity dominate over that in external solution is nontrivial. − Therefore, the spatially restricted formation of NCs in the seed-free interior solution remains a compelling but challenging task that can extend the utility of hollow nanoreactors toward the study of the rarely explored NC nucleation process and eventually help to improve the efficiency and controllability of the processes to produce NC-based materials. As a key element for addressing this challenging topic, we employed cucurbituril (CB), a pumpkin-shaped macrocycle with a high affinity for both metal ions and reduced metallic surfaces. − The unique structure of CB is thought to influence the formation and stabilization of metal NCs, featuring two strongly coordinating portals surrounded by multiple polar carbonyl groups. − Our strategy initially relied on the hypothesis that the harboring of CB-containing hollow nanoreactors in an NC-growing solution might facilitate the solid-phase nucleation from the solution inside the cavity and allow the NC formation to preferentially occur in the reactor interior.…”