Black phosphorus (BP), as an emerging successor to layered two-dimensional materials, has attracted extensive interest in cancer therapy. Toxicological studies on BP are of great importance for potential biomedical applications, yet not systemically explored. Herein, toxicity and oxidative stress of BP quantum dots (BPQDs) at cellular, tissue, and whole-body levels are evaluated by performing the systemic in vivo and in vitro experiments. In vitro investigations show that BPQDs at high concentration (200 μg/mL) exhibit significant apoptotic effects on HeLa cells. In vivo investigations indicate that oxidative stress, including lipid peroxidation, reduction of catalase activity, DNA breaks, and bone marrow nucleated cells (BMNC) damage, can be induced by BPQDs transiently but recovered gradually to healthy levels. No apparent pathological damages are observed in all organs, especially in the spleen and kidneys, during the 30-day period. This work clearly shows that BPQDs can cause acute toxicities by oxidative stress responses, but the inflammatory reactions can be recovered gradually with time for up to 30 days. Thus, BPQDs do not give rise to long-term appreciable toxicological responses.

Catalytic nanomaterials can be used extrinsically to combat diseases associated with a surplus of reactive oxygen species (ROS). Rational design of surface morphologies and appropriate doping can substantially improve the catalytic performances. In this work, a class of hollow polyvinyl pyrrolidone-protected PtPdRh nanocubes with enhanced catalytic activities for in vivo free radical scavenging is proposed. Compared with Pt and PtPd counterparts, ternary PtPdRh nanocubes show remarkable catalytic properties of decomposing H O via enhanced oxygen reduction reactions. Density functional theory calculation indicates that the bond of superoxide anions breaks for the energetically favorable status of oxygen atoms on the surface of PtPdRh. Viability of cells and survival rate of animal models under exposure of high-energy γ radiation are considerably enhanced by 94% and 50% respectively after treatment of PtPdRh nanocubes. The mechanistic investigations on superoxide dismutase (SOD) activity, malondialdehyde amount, and DNA damage repair demonstrate that hollow PtPdRh nanocubes act as catalase, peroxidase, and SOD analogs to efficiently scavenge ROS.

Two-dimensional WS 2 materials have attracted wide attention in condensed physics and materials science due to its unique geometric and electronic structures. Particularly, WS 2 shows extraordinary catalytic activities when its size decreases to ultrasmall, which provides potential opportunities for medical applications. In this work, WS 2 quantum dots with strong catalytic properties were used for in vitro and in vivo protection from ionizing radiation induced cell damages. WS 2 quantum dots possess unique optical properties of blue photoluminescence emission and excitation-wavelength dependent emission profiles. In vitro studies showed that cell viability can be considerably improved and cellular reactive oxygen species (ROS) can be removed by WS 2 quantum dots. In vivo studies showed WS 2 quantum dots can effectively protect the hematopoietic system and DNA from damages caused by high-energy radiation through removing whole-body excessive ROS. Furthermore, WS 2 quantum dots showed nearly 80% renal clearance within 24 h post injection and did not cause any obvious toxicities in up to 30 days after treatment.

High‐energy ionizing radiation is widely used in medical diagnosis and cancer radiation therapy. However, high‐energy radiation can also impose significant damages in healthy tissues during medical treatments via direct DNA damages and indirect damages from production of reactive oxygen species (ROS). Therefore, it is urgent to develop highly effective radioprotectants with low toxicities that can meet the increasing needs for alleviating the adverse effects from cancer radiation therapy and nuclear emergency. In this work, strongly catalytic ultrasmall (sub‐5 nm) cysteine‐protected WSe2 dots are employed to protect healthy tissues against radiation via diminishing radiation‐induced free radicals. The WSe2 dots with high surface activities can recover radiation‐induced DNA damages and eliminate the excessive ROS generated from radiation. In vivo experiments confirm that the survival rate of mice treated with WSe2 dots is significantly elevated with radiation damages postponed under exposure to high‐dose ionizing radiation. Furthermore, the free radicals in major organs and hematological system can be appreciably omitted, suggesting their unique role as free radical scavengers. These WSe2 dots in ultrasmall size show rapid renal clearance of ≈74% injection dose via urine excretion in 24 h and do not cause any apparent toxicity in vivo for up to 30 d.

Rapid urbanization of China has brought lifestyle changes resulting in a continuous decline in children’s physical fitness (PF) and out-of-school physical activity (PA). To date, studies have been focused on correlates of PF and out-of-school PA, and patterns and trends based on geographic diversity and urban-rural contrasts. Western China, with a large rural population, has substantial urban-rural differences, but little work has been done to compare its children’s physical fitness (PF) and out-of-school physical activity (PA) at a county level. A total of 715 primary school students (grades 3–6) were surveyed from one urban school (n = 438) and four rural schools (n = 277) in a county-level administrative unit, Yangling District, Shaanxi, in western China. Physical fitness index (PFI) was measured and calculated based on the revised Chinese Student Physical Fitness Standards. Out-of-school PA and other variables of demographics, behavior and perception were collected using questionnaires. Statistical analyses explored urban-rural differences and correlates of PFI and out-of-school PA. We found that the PFI (72.86 vs. 79.67) and weekly moderate-to-vigorous physical activity (MVPA) duration (167.57 vs. 220.08) of urban students were significantly lower than those of rural students. Weekly MVPA duration had the largest positive impact on PFI. Perceived availability of PA spaces was positively associated with both the urban and rural students’ PF and PA, while screen time was negatively associated with PF and PA, especially for rural students. Facilitators of PA frequency include the perceived availability of PA time and parental educational level. Parents’ PA habits had a positive impact on urban students’ PA. No association between active school commuting and PF or PA was found. Our findings revealed that PF and out-of-school PA of urban students were clearly lower than among rural students. The health of rural children at the county level in western China should be paid much more attention during the process of rapid urbanization.