Single Molecular Nanomedicines Based on Macrocyclic Carrier-Drug Conjugates for Concentration-Independent Encapsulation and Precise Activation of Drugs.

Nanomedicines often rely on noncovalent self-assembly and encapsulation for drug loading and delivery. However, challenges such as reproducibility issues due to the multicomponent nature, off-target activation caused by premature drug release, and complex pharmacokinetics arising from assembly dissociation have hindered their clinical translation. In this study, we introduce an innovative design concept termed single molecular nanomedicine (SMNM) based on macrocyclic carrier-drug conjugates. Through the covalent linkage of two chemotherapy drugs to a hypoxia-cleavable macrocyclic carrier, azocalix[4]arene, we obtained two self-included complexes to serve as SMNMs. The intramolecular inclusion feature of the SMNMs has not only demonstrated comprehensive shielding and protection for the drugs but also effectively prevented off-target drug leakage, thereby significantly reducing their side effects and enhancing their antitumor therapeutic efficacy. Additionally, the attributes of being a single component and molecularly dispersed confer advantages such as ease of preparation and good reproducibility for SMNMs, which is desirable for clinical applications.

An Antitumor Dual-Responsive Host-Guest Supramolecular Polymer Based on Hypoxia-Cleavable Azocalix[4]arene.

The exploitation of specific guests which can respond to external stimuli is the main approach for the construction of stimuli-responsive supramolecular polymers (SPs) based on host-guest interactions. Most functional guests, however, fail to manifest stimuli-responses. Herein, a hypoxia-responsive dimeric azocalixarene (D-SAC4A) with outstanding hosting properties was used as the macrocyclic building block for the preparation of host stimuli-responsive SPs. Since azocalixarenes can also be compatible with stimuli-responsive guests, an antitumor drug, camptothecin (CPT), was chosen and linked via a disulfide-containing linker to afford a glutathione (GSH)-responsive ditropic guest (D-CPT). A unique dual-responsive SP was obtained by 1 : 1 mixing of D-SAC4A and D-CPT in water, which further assembled into SP nanoparticles (DSPNs). DSPNs displayed outstanding stability against dilution and biological interferants, as well as precise CPT-release under GSH and hypoxia conditions. In vitro and in vivo experiments demonstrated the good biosafety and tumor-suppressive effects of DSPNs.

Sulfonated Azocalix[4]arene-Modified Metal-Organic Framework Nanosheets for Doxorubicin Removal from Serum.

Chemotherapy is one of the most commonly used methods for treating cancer, but its side effects severely limit its application and impair treatment effectiveness. Removing off-target chemotherapy drugs from the serum promptly through adsorption is the most direct approach to minimize their side effects. In this study, we synthesized a series of adsorption materials to remove the chemotherapy drug doxorubicin by modifying MOF nanosheets with sulfonated azocalix[4]arenes. The strong affinity of sulfonated azocalix[4]arenes for doxorubicin results in high adsorption strength (Langmuir adsorption constant = 2.45-5.73 L mg-1) and more complete removal of the drug. The extensive external surface area of the 2D nanosheets facilitates the exposure of a large number of accessible adsorption sites, which capture DOX molecules without internal diffusion, leading to a high adsorption rate (pseudo-second-order rate constant = 0.0058-0.0065 g mg-1 min-1). These adsorbents perform effectively in physiological environments and exhibit low cytotoxicity and good hemocompatibility. These features make them suitable for removing doxorubicin from serum during "drug capture" procedures. The optimal adsorbent can remove 91% of the clinical concentration of doxorubicin within 5 min.