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Next-generation nanozyme based biosensing: mesoporous nanocrystalline α- or γ-iron oxide?

The corresponding global annual carbon dioxide (CO 2 ) emissions had also increased from 23.1 gigatonnes of CO 2 (Gt CO2 ) in 2000 to 33.2 Gt CO2 in 2018. The excessive reliance on fossil fuels has caused the atmospheric CO 2 concentration to increase from the pre-industrial 280 ppm in the 18th century to the annual average of more than 410 ppm nowadays, which is found to be positively correlated to climate change. [2] To alleviate the environmental issues and to find viable alternatives for depleting fossil fuel reserves, the development and largescale deployment of clean and sustainable energy systems is of utmost importance. The development of suitable energy carriers is necessary to enable energy storage and distribution and to overcome the deficiency due to the intermittency of renewable energy sources such as solar and wind power. The use of H 2 has a great potential to diversify energy sectors and to prepare for the future implementation of low-carbon electricity and renewable energy. H 2 fuel cell (FC) technology is considered mature and regarded as the only technology to realize mobility without change of habits. As stated in the 2019 report by International Energy Agency to G20, H 2 is expected "to play a key role in a clean, secure and affordable energy future." [3] However, due to the lack of viable technologies for safe, efficient, and economical storage and transportation of H 2 , the applications of hydrogen have significantly been limited. [4] The storage and utilization of low-carbon electricity and decarbonization of transportation are essential components for the future energy transition into a low-carbon economy. While hydrogen has been identified as a potential energy carrier, the lack of viable technologies for safe and efficient storage and transportation of H 2 greatly limits its applications and deployment at scale. Formic acid (FA) is considered one of the promising H 2 energy carriers because of its high volumetric H 2 storage capacity of 53 g H 2 /L, and relatively low toxicity and flammability for convenient and low-cost storage and transportation. FA can be employed to generate electricity either in direct FA fuel cells (FCs) or indirectly as an H 2 source for hydrogen FCs. FA can enable large-scale chemical H 2 storage to eliminate energy-intensive and expensive processes for H 2 liquefaction and compression and thus to achieve higher efficiency and broader utilization. This perspective summarizes recent advances in catalyst development for selective dehydrogenation of FA and high-pressure H 2 production. The advantages and limitations of FA-to-power options are highlighted. Existing life cycle assessment (LCA) and economic analysis studies are reviewed to discuss the feasibility and future potential of FA as a fuel.

Mesoporous iron-oxide nanoparticles (mNPs) were prepared by using a modified nanocasting approach with mesoporous carbon as a hard template. mNPs were first loaded with doxorubicin (Dox), an anticancer drug, and then coated with the thermosensitive polymer Pluronic F108 to prevent the leakage of Dox molecules from the pores that would otherwise occur under physiological conditions. The Dox-loaded, Pluronic F108-coated system (Dox@F108-mNPs) was stable at room temperature and physiological pH and released its Dox cargo slowly under acidic conditions or in a sudden burst with magnetic heating. No significant toxicity was observed in vitro when Dox@F108-mNPs were incubated with noncancerous cells, a result consistent with the minimal internalization of the particles that occurs with normal cells. On the other hand, the drug-loaded particles significantly reduced the viability of cervical cancer cells (HeLa, IC =0.70 μm), wild-type ovarian cancer cells (A2780, IC =0.50 μm) and Dox-resistant ovarian cancer cells (A2780/AD, IC =0.53 μm). In addition, the treatment of HeLa cells with both Dox@F108-mNPs and subsequent alternating magnetic-field-induced hyperthermia was significantly more effective at reducing cell viability than either Dox or Dox@F108-mNP treatment alone. Thus, Dox@F108-mNPs constitute a novel soft/hard hybrid nanocarrier system that is highly stable under physiological conditions, temperature-responsive, and has chemo- and thermotherapeutic modes of action.

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