Gated Materials: Installing Macrocyclic Arenes‐Based Supramolecular Nanovalves on Porous Nanomaterials for Controlled Cargo Release

Abstract

Supramolecular nanovalves are an emerging class of important elements that are functionalized on the surfaces of inorganic or hybrid nanocarriers in the constructions of smart cargo delivery systems. Taking advantage of the pseudorotaxane structure via host‐guest complexation and the dynamic nature of supramolecular interactions, macrocyclic arene‐based supramolecular nanovalves have shown great promise in the applications of drug delivery and controlled release. Careful selection of diverse external stimuli, such as pH variations, temperature changes, redox, enzymes, light irradiation, and competitive binding, can activate the opening and closing of the nanovalves by altering the supramolecular structure or binding affinities. Meanwhile, the porous solid supports in controlled release systems also play an important role in the functionalities of the nanocarriers, which include, but not limited to, mesoporous silica nanoparticles (MSNs), metal‐organic frameworks (MOFs), core‐shell nanomaterials, and rare‐earth porous nanomaterials. The elaborate decoration by macrocyclic arenes‐based supramolecular nanovalves on porous nanomaterials has provided intelligent controlled release platforms. In this review, we will focus on the overview of supramolecular nanovalves based on two typical macrocyclic arenes, that is, calixarenes and pillarenes, and their operation manners in the controlled release processes.

Stimuli-Responsive Drug-Delivery Systems Based on Supramolecular Nanovalves

“…Therefore a broad scope of solid scaffolds, including mesoporous silica NPs (MSNs), metal-organic frameworks (MOFs), and other inorganic NPs, has been used to prepare organic-inorganic hybrid supramolecular drug-delivery systems. [29][30][31] Taking advantage of their porous structures, large surface areas, considerable loading capacity, and easily modified surface, a huge number of drug molecules (i.e., chlorambucil, camptothecin, 5-fluorouracil , busulfan, cisplatin prodrug, gemcitabine, and doxorubicin) have been encapsulated into the carriers for further precise release within solid tumors. [32][33][34][35][36][37] To further overcome the existing biological barriers, scientists have made great efforts to modify carriers with targeted biomarker species, allowing progress in supramolecular nanovalves and present their applications in cancer/gene therapy and antibacterial regulations.…”

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe3+ sensing

“…Synthetic macrocyclic compounds, especially new macrocyclic arenes, have become one of the research hotspots in supramolecular chemistry [11–14]. Among them pillarenes as a relatively new family of pillar-shaped members discovered a decade ago have played a key role due to their unique conformations, symmetrical structures, superior host–guest properties, supramolecular assembly characteristics, and versatile functionalities [11,15–16]. Carboxylatopillar[5]arene (CP[5]) is one of the most popular functional pillarenes that has been exploited in many research areas, especially in sensing and detection [16–21].…”

Towards Universal Stimuli-Responsive Drug Delivery Systems: Pillar[5]arenes Synthesis and Self-Assembly into Nanocontainers with Tetrazole Polymers

“…To address the problem, it was proposed to use various multifunctional macrocyclic compounds capable of controlled interaction with the polymer, which leads to the formation of stable associates in water [12]. Today, the most promising macrocyclic compounds are representatives of a new class of para-cyclophanes-pillar[n]arenes [13][14][15]. Pillar [n]arenes are macrocyclic compounds in which fragments of substituted hydroquinones are interconnected by methylene bridges [13].…”