Yu-Long Sun

Viologen-Mediated Assembly of and Sensing with Carboxylatopillar[5]arene-Modified Gold Nanoparticles

Carboxylatopillar[5]arene (CP[5]A), a new water-soluble macrocyclic synthetic receptor, has been employed as a stabilizing ligand for in situ preparation of gold nanoparticles (AuNPs) to gain new insights into supramolecular host-AuNP interactions. CP[5]A-modified AuNPs with good dispersion and narrow size distributions (3.1 ± 0.5 nm) were successfully produced in aqueous solution, suggesting a green synthetic pathway for the application of AuNPs in biological systems. Supramolecular self-assembly of CP[5]A-modified AuNPs mediated by suitable guest molecules was also investigated, indicating that the new hybrid material is useful for sensing and detection of the herbicide paraquat.

Mechanized Silica Nanoparticles Based on Pillar[5]arenes for On-Command Cargo Release

Mechanized silica nanoparticles, equipped with pillar[5]arene-[2]pseudorotaxane nanovalves, operate in biological media to trap cargos within their nanopores, but release them when the pH is lowered or a competitive binding agent is added. Although cargo size plays an important role in cargo loading, cargo charge-type does not appear to have any significant influence on the amount of cargo loading or its release. These findings open up the possibility of using pillar[n]arene and its derivatives for the formation of robust and dynamic nanosystems that are capable of performing useful functions.

Near-infrared light-responsive supramolecular nanovalve based on mesoporous silica-coated gold nanorods

We constructed a novel cancer theranostic hybrid platform, based on mesoporous silica-coated gold nanorods (AuNR@MSN) gated by sulfonatocalix[4]arene (SC[4]A) switches, for bio-friendly near-infrared (NIR) light-triggered cargo release in a remote and stepwise fashion. The advantages of supramolecular switches, mesoporous silicas, and AuNRs were combined in one drug delivery system. Mesoporous silicas coated on AuNRs guarantee a high drug payload and can be easily post-functionalized. Significantly, the plasmonic heating from the NIR light-stimulated AuNR cores can decrease the ring-stalk binding affinity, leading to the dissociation of SC[4]A rings from the stalks, thus opening the nanovalves and releasing the cargos. The NIR light-responsive mechanized AuNR@MSN offers exciting prospects for non-invasive controlled drug delivery, being more effective and safer than other techniques.

Mesoporous Silica Nanoparticles Coated by Layer-by-Layer Self-assembly Using Cucurbit[7]uril for in Vitro and in Vivo Anticancer Drug Release.

Mesoporous silica nanoparticles (MSNs) are promising solid supports for controlled anticancer drug delivery. Herein, we report biocompatible layer-by-layer (LbL) coated MSNs (LbL-MSNs) that are designed and crafted to release encapsulated anticancer drugs, e.g., doxorubicin hydrochloride (DOX), by changing the pH or by adding competitive agents. The LbL coating process comprises bis-aminated poly(glycerol methacrylate)s (BA-PGOHMAs) and cucurbit[7]uril (CB[7]), where CB[7] serves as a molecular bridge holding two different bis-aminated polymeric layers together by means of host–guest interactions. This integrated nanosystem is tuned to respond under specific acidic conditions or by adding adamantaneamine hydrochloride (AH), attributed to the competitive binding of hydronium ions or AH to CB[7] with BA-PGOHMAs. These LbL-MSN hybrids possess excellent biostability, negligible premature drug leakage at pH 7.4, and exceptional stimuli-responsive drug release performance. The pore sizes of the MSNs and bis-aminated compounds (different carbon numbers) of BA-PGOHMAs have been optimized to provide effective integrated nanosystems for the loading and release of DOX. Significantly, the operating pH for the controlled release of DOX matches the acidifying endosomal compartments of HeLa cancer cells, suggesting that these hybrid nanosystems are good candidates for autonomous anticancer drug nanocarriers actuated by intracellular pH changes without any invasive external stimuli. The successful cellular uptake and release of cargo, e.g., propidium iodide (PI), in human breast cancer cell line MDA-231 from PI-loaded LbL-MSNs have been confirmed by confocal laser scanning microscopy (CLSM), while the cytotoxicities of DOX-loaded LbL-MSNs have been quantified by the Cell Counting Kit-8 (CCK-8) viability assay against HeLa cell lines and fibroblast L929 cell lines. The uptake of DOX-loaded LbL-MSNs by macrophages can be efficiently reduced by adding biocompatible hydrophilic poly(ethylene glycol) or CB[7] without destroying the capping. In vivo tumor-growth inhibition experiments with BALB/c nude mice demonstrated a highly efficient tumor-growth inhibition rate of DOX-loaded LbL-MSNs, suggesting that the novel type of LbL-MSN materials hold great potentials in anticancer drug delivery.

Pillararene-functionalized Fe3O4 nanoparticles as magnetic solid-phase extraction adsorbent for pesticide residue analysis in beverage samples

Hybrid materials based on magnetic Fe3O4 nanoparticles and synthetic macrocyclic receptor, carboxylatopillar[5]arene, have been successfully prepared as a magnetic solid phase extraction (MSPE) adsorbent for the determination of trace pesticides in beverage samples, coupled with high-performance liquid chromatography (HPLC). The effects of various parameters, i.e., the amount of adsorbents, extraction and desorption times, desorption solvent, ionic strength, and sample pH, have been investigated and optimized. The detection limits for seven pesticides are in the range of 5.0–11.3 ng mL−1. The recoveries for all target analytes are over the range of 70.6% to 106.8% with the intra-day and inter-day relative standard deviations less than 7.2% and 8.0%, respectively. The newly developed MSPE-HPLC method has been successfully employed to determine pesticide residues in beverage samples.

Supramolecular self-assembly and photophysical properties of pillar[5]arene-stabilized CdTe quantum dots mediated by viologens

Carboxylatopillar[5]arene (CP[5]A) functionalized CdTe quantum dots (CP[5]A@QDs) were synthesized via a ligand-exchange method and shown to be very stable in basic aqueous solutions. Significantly, CP[5]As can be modified on the surfaces of QDs to stabilize the photochemical properties of CdTe nanocrystals and serve as bridges to induce the formation of an aggregated supramolecular network upon the addition of bridged methyl viologen guest molecules.

Stimuli-responsive biocompatible nanovalves based on β-cyclodextrin modified poly(glycidyl methacrylate)

β-Cyclodextrins (β-CDs) were grafted onto star-shaped poly(glycidyl methacrylate)s (S5-PGMAs) with a straightforward and efficient ring-opening addition of amine groups to result in PGMA–CDs, which not only possess good water-solubility and biocompatibility, but also can serve as polymeric supramolecular hosts to form inclusion complexes with suitable guests. They can be easily assembled on the surface of azobenzene-functionalized mesoporous silica nanoparticles (MSNs) via host–guest interactions to obtain MSN@PGMA–CD hybrid nanoparticles, which have been fully characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and elemental analysis. The experimental results showed that these types of inorganic–organic hybrid mesoporous nanocomposites possess good cargo encapsulation and release properties, as compared with the simple supramolecular nanovalves with β-CD itself as the gating component, upon activation by light, temperature variation, and competitive binding agents. In addition, the extremely low cytotoxicity of the nanocomposites demonstrated by MTT assay can further broaden their applications in controlled drug release.