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The integration of hypoxia-activated chemotherapy with photodynamic therapy (PDT) has newly become a potent strategy for tumor treatment. Herein, a reactive oxygen species (ROS)-responsive drug carriers (PS@AQ4N/mPEG-b-PSe NPs) are fabricated based on the amphiphilic selenium-containing methoxy poly(ethylene glycol)-polycarbonate (mPEG-b-PSe), the hydrophobic photosensitizer (PS), and hypoxia-activated prodrug Banoxantrone (AQ4N). The obtained nanoparticles are spherical with an average diameter of 100 nm as characterized by transmission electron microscope (TEM) and dynamic laser scattering (DLS) respectively. The encapsulation efficiency of the PS and AQ4N reaches 92.83% and 51.04% at different conditions, respectively, by UV-vis spectrophotometer. It is found that the drug release is accelerated due to the good ROS responsiveness of mPEG-b-PSe and the cumulative release of AQ4N is up to 89% within 30 h. The cell test demonstrates that the nanoparticles dissociate when triggered by the ROS stimuli in the cancer cells, thus the PS is exposed to more oxygen and the ROS generation efficiency is enhanced accordingly. The consumption of oxygen during PDT leads to the increased tumor hypoxia, and subsequently activates AQ4N into cytotoxic counterpart to inhibit tumor growth. Therefore, the synergistic therapeutic efficacy demonstrates this drug delivery has great potential for antitumor therapy.

With ongoing global climate change and human activities, increasing desertification plays a predominant role in increasing soil nutrient losses. Soil nitrogen (N) is the essential limiting nutrient supporting plant growth and evaluating soil nutrient content, especially in desert ecosystems. N microbial processes will ultimately restore and maintain the balance in the soil N cycle, but the damage caused by desertification to soil N functional microorganisms associated with N supply, transformation, and loss is poorly understood. We examined changes in soil N and N functional gene (NFG) abundances within vertical profiles (i.e., soil depths of 0–100 cm) throughout the desertification process. We found that the abundance of N functional genes (NFGs) (except the N-fixation gene) decreased during the desertification process, almost all NFGs were attenuated along the vertical profiles, and available phosphorus (AP), soil water content (SWC) and pH were the best explanatory variables. The sums of (AOA + AOB) (associated with available N transformation) and (nirK + nirS + qnorB + nosZ) (associated with N loss) significantly decreased as desertification progressed, leading to decreased N transformation and loss potential. The (nifH + chiA) associated with available N supply increased along the desertification process gradient, suggesting enhanced potential for the acquisition available N. The increased ratio of (nifH + chiA + AOA + AOB)/(nirK + nirS + qnorB + nosZ) (associated with available N storage) collaboratively contributed to enhanced available N storage potential throughout the desertification process. Our results lay the foundation for better understanding the distinct responses of NFGs to desertification and the process through which they ultimately regulate available N storage in the degraded soils of desert ecosystems.