Zehuan Huang

Supramolecular Polymerization Promoted and Controlled through Self‐Sorting

A new method in which supramolecular polymerization is promoted and controlled through self-sorting is reported. The bifunctional monomer containing p-phenylene and naphthalene moieties was prepared. Supramolecular polymerization is promoted by selective recognition between the p-phenylene group and cucurbit[7]uril (CB[7]), and 2:1 complexation of the naphthalene groups with cucurbit[8]uril (CB[8]). The process can be controlled by tuning the CB[7] content. This development will enrich the field of supramolecular polymers with important advances towards the realization of molecular-weight and structural control.

Porphyrin-containing hyperbranched supramolecular polymers: enhancing 1O2-generation efficiency by supramolecular polymerization

Hyperbranched supramolecular polymers were obtained by mixing a naphthyl-substituted porphyrin derivative and cucurbit[8]uril in aqueous solution, which was driven by host–guest interactions. The formation of a supramolecular polymeric structure can cause disruption of the porphyrin aggregation, thus leading to enhancement of their 1O2-generation efficiency.

Water-soluble supramolecular polymers fabricated through specific interactions between cucurbit[8]uril and a tripeptide of Phe-Gly-Gly

A bifunctional monomer FGG-PEG8-GGF bearing two Phe-Gly-Gly residues and an octaethylene glycol linker has been designed and synthesized. Water-soluble supramolecular polymers can form spontaneously by mixing the monomer and cucurbit[8]uril (CB[8]) in a 1 : 1 ratio through specific interactions between CB[8] and the Phe-Gly-Gly residues.

Amphiphilic diselenide-containing supramolecular polymers

This communication describes the fabrication of diselenide-containing supramolecular polymers. The diselenide-containing supramolecular polymers were fabricated by equimolarly mixing (FGGC11Se)2 and CB[8] in aqueous solution driven by host–guest interactions between cucurbit[8]uril (CB[8]) and Phe-Gly-Gly. The amphiphilic diselenide-containing supramolecular polymers could further form aggregates for loading hydrophobic small molecules such as Nile Red and releasing them upon addition of oxidants or reductants. This line of research not only expands the library of selenium-containing polymers, but also offers a new strategy to develop functional supramolecular polymers for drug delivery.

Controllable supramolecular polymerization through self-sorting of aliphatic and aromatic motifs

Self-sorting is one of the effective strategies to realize control over supramolecular polymerization. In this work, we designed a bifunctional monomer (Np-Cn-Np) bearing an alkyl chain (Cn) and two naphthalene moieties (Np). By mixing the monomer with two kinds of host molecules, the selective recognition between Np and cucurbit[8]uril (CB[8]) can link up the monomer, and the complexation between Cn and cucurbit[7]uril (CB[7]) can construct a rigid linker to promote and control the linear supramolecular polymerization. The self-sorting process was confirmed by 1H NMR and isothermal titration calorimetry. As indicated by analytical ultracentrifugation, the molecular weight of supramolecular polymers can be well tuned from 10 kDa to 50 kDa by tuning the molar ratio of CB[7] to Np-C6-Np. Adjustment of the length of the alkyl chain can influence the degree of polymerization, which was studied through isothermal titration calorimetry and diffusion-ordered NMR spectroscopy. In addition, the kinetics of the supramolecular polymerizations were studied by stopped flow. This line of research will extend the self-sorting strategy to achieve controllable supramolecular polymerization and enrich the field of supramolecular polymers.

Controlling the Reactivity of the SeSe Bond by the Supramolecular Chemistry of Cucurbituril

We describe a new strategy to control the reactivity of SeSe bond by using supramolecular chemistry of cucurbituril. We have demonstrated that selenocystamine (SeCy) and cucurbit[6]uril (CB[6]) can form a stable supramolecular complex (Ka =5.5×10(6)  M(-1) ). Before complexation, the free SeSe bond in SeCy is rather sensitive to redox stimuli and gets disrupted quickly with addition of reductant or oxidant. However, after binding with CB[6], the SeSe bond becomes quite inert and hardly reacts with reductant or oxidant. One advantage of this supramolecular protection is that it can be applied in a wide pH range from weakly acidic to basic. Additionally, the supramolecular complex formed by SeCy and CB[6] can be reversibly dissociated simply with addition of Ba(2+) .

Cytotoxicity Regulated by Host–Guest Interactions: A Supramolecular Strategy to Realize Controlled Disguise and Exposure

This work is aimed at providing a supramolecular strategy for tuning the cytotoxicity in chemotherapy. To this end, as a proof of concept, we employed dynamic cucurbit[7]uril(CB[7])-mediated host-guest interaction to control the loading and releasing of dimethyl viologen (MV) as a model antitumor agent. MV has high cytotoxicity to both normal cells and tumor cells without specificity. By encapsulating MV into the hydrophobic cavity of CB[7], the cytotoxicity of MV to normal cells can be significantly decreased. When the host-guest complex of MV-CB[7] is added into tumor cells with overexpressed spermine, the antitumor activity of MV can be recovered in tumor cell environment. There are two reasons behind this effect: on the one hand, spermine has a high affinity to CB[7], leading to releasing of MV from MV-CB[7]; on the other hand, CB[7] can soak up spermine, which is essential for tumor cell growth, therefore decreasing the cell viability furthermore. Then, it is highly anticipated that this kind of supramolecular strategy could apply to clinical antitumor agents and provide a new approach for decreasing the cytotoxicity and increasing the antitumor activity, thus opening horizons of supramolecular chemotherapy.

Supramolecular Interfacial Polymerization: A Controllable Method of Fabricating Supramolecular Polymeric Materials

Abstract A new method of supramolecular polymerization at the water–oil interface is developed. As a demonstration, an oil‐soluble supramonomer containing two thiol end groups linked by two ureidopyrimidinone units and a water‐soluble monomer bearing two maleimide end groups are employed. Supramolecular interfacial polymerization can be implemented by a thiol–maleimide click reaction at the water–chloroform interface to obtain supramolecular polymeric films. The glass transition temperature of such supramolecular polymers can be well‐tuned by simply changing the polymerization time and temperature. It is highly anticipated that this work will provide a facile and general approach to realize control over supramolecular polymerization by transferring the preparation of supramolecular polymers from solutions to water–oil interfaces and construct supramolecular materials with well‐defined properties.

Supramolecular Chemotherapy: Cooperative Enhancement of Antitumor Activity by Combining Controlled Release of Oxaliplatin and Consuming of Spermine by Cucurbit[7]uril

Supramolecular chemotherapy is aimed to employ supramolecular approach for regulating the cytotoxicity and improving the efficiency of antitumor drugs. In this paper, we demonstrated a new example of supramolecular chemotherapy by utilizing the clinical antitumor drug, oxaliplatin, which is the specific drug for colorectal cancer treatment. Cytotoxicity of oxaliplatin to the colorectal normal cell could be significantly decreased by host-guest complexation between oxaliplatin and cucurbit[7]uril (CB[7]). More importantly, oxaliplatin-CB[7] exhibited cooperatively enhanced antitumor activity than oxaliplatin itself. On the one hand, the antitumor activity of oxaliplatin can reappear by competitive replacement of spermine from oxaliplatin-CB[7]; on the other hand, CB[7] can consume the overexpressed spermine in tumor environments, which is essential for tumor cell growth. These two events can lead to the cooperatively enhanced antitumor performance. Supramolecular chemotherapy can be applied to treat with spermine-overexpressed tumors. It is highly anticipated that this strategy may be employed in many other clinical antitumor drugs, which opens a new horizon of supramolecular chemotherapy for potential applications in clinical antitumor treatments.

Supramolecular Chemotherapy: Carboxylated Pillar[6]arene for Decreasing Cytotoxicity of Oxaliplatin to Normal Cells and Improving Its Anticancer Bioactivity Against Colorectal Cancer

We have successfully demonstrated that the host-guest complex of carboxylated pillar[6]arene with oxaliplatin (OxPt) exhibits low cytotoxicity toward normal cells and displays higher anticancer bioactivity against colorectal cancer cells than OxPt itself. Owing to higher binding affinity of carboxylated pillar[6]arene with spermine (SPM) than that with OxPt, the encapsulated OxPt can be thoroughly released from its host-guest complex by the competitive replacement with SPM. This supramolecular chemotherapy works well both in vitro and in vivo for SPM-overexpressed cancers, such as colorectal cancer. Compared to OxPt itself, the anticancer bioactivity of this host-guest complex is further improved by about 20%. Such an improvement results from the combined effect of controlled release of OxPt from its host-guest complex and simultaneous consumption of SPM by carboxylated pillar[6]arene. It is anticipated that this supramolecular strategy may be extended to other clinical anticancer drugs for decreasing their severe side effects and improving their anticancer bioactivity, thus enriching the realm of supramolecular chemotherapy.