The safety of nanoparticle-based drug delivery systems (DDSs) for cancer treatment is still a challenge, restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug. Here, we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8 (ZIF-8)-based colloid particles (CPs) with an amorphous ZIF-8 skin. This encapsulation structure achieves an ultra-high loading rate (LR) of 90% (i.e., 9 mg doxorubicin (DOX) per 1 mg ZIF-8) for DOX and the protection of DOX from leaking. Notably, to deliver unit-dose drug, this ultra-high LR of 90% significantly reduces the usage of ZIF-8 to 1.2% (2 orders of magnitude) compared to that of DOX@ZIF-8 with a 10% LR, in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored. Safety, drug delivery efficacy, scale-up ability, and universality of this encapsulation structure have been further verified. Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.

There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations, thus it is necessary to develop new catalysts for efficient CO oxidation. Based on first-principles calculations, the potential of γ-graphyne (GY) as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated. It was found that single-atom Co, Ir, Rh, and Ru could effectively oxidate CO molecules, especially for single Rh. Furthermore, proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers, such as Rh₂/GY. It was determined that two Rh atoms in Rh₂/GY act different roles in the catalytic reaction: one structural and another functional. Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost. This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates. We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance. This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.