As one of the typical bioorthogonal reactions, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction holds great potential in organic synthesis, bioconjugation, and surface ...functionalization. However, the toxicity of Cu(I), inefficient catalytic activity, and the lack of cell specific targeting of the existing catalysts hampered their practical applications in living systems. Herein, we design and construct a DNA-based platform as a biocompatible, highly efficient, and precisely targeted bioorthogonal nanocatalyst. The nanocatalyst presents excellent catalytic efficiency in vitro, which is one order of magnitude higher than the commonly used catalyst CuSO
/sodium ascorbate. The theoretical calculation further supports the contribution of DNA structure and its interaction with substrates to the superior catalytic activity. More importantly, the system can achieve efficient prodrug activation in cancer cells through cell type-specific recognition and produce a 40-fold enhancement of transformation compared to the non-targeting nanocatalyst, resulting in enhanced antitumor efficacy and reduced adverse effects. In vivo tumor therapy demonstrates the safety and efficacy of the system in mammals.
Owing to better stability and biosafety, heterogeneous Cu nanoparticles (CuNPs) have been put forward as a promising candidate to complete the Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) ...reaction. However, the inherent poor activity of Cu(0) deterred its wide bioapplication. Herein, we employed near-infrared (NIR) light to dual-promote the CuAAC reaction of a biocompatible heterogeneous copper nanocatalyst through photodynamic and photothermal effects in vitro and in vivo. Specifically, the photodynamic activity could promote the conversion of Cu(0) to Cu(I) to accelerate the catalytic process of CuAAC. The high photothermal conversion efficiency (η = 50.6%) could increase the local temperature, further promoting the whole reaction. Then, a drastically increased reaction rate in a living system ranging from cells to nematodes was achieved in our system. Meanwhile, the better antitumor efficacy has determined with in vivo tumor therapy experiments.
This study proposes using the network of urban gardens to grow vegetables and to monitor air quality, and it also evaluates whether food grown on a clean substrate in an urban environment is safe for ...consumption. For this purpose, lettuces were exposed to different degrees of air pollution in five locations in the city of Copenhagen, plus a reference site. Six specimens were placed at each site and, after the exposure period, half of each sample was washed. Subsamples were then digested by a total extraction method and a bioaccessible extraction method, and the concentration of 23 elements subsequently measured by ICP-MS. The results showed that exposed samples in areas of higher atmospheric pollution accumulated a larger amount of trace elements associated with typical urban sources. They also highlighted the importance of washing food to remove particles that adhere to their surface. However, bioaccessibility testing demonstrated the importance of including bioaccessibility in risk analyses and how this factor varies depending on the type of matrix. In this case, bioaccessibility was higher for plant tissue than for particulate matter. Lastly, metal concentrations in lettuce were compared with legal values and an analysis of daily intake showed that the levels in Copenhagen were within limits for the protection of human health.
Display omitted
•Urban gardens can be used as sites for biomonitoring of atmospheric pollution levels.•Many urban-related pollutants are primarily associated with PM deposited on leaves.•It is advisable to grow food in low-traffic areas and wash it thoroughly.•Trace element bioaccessibility values vary depending on the type of solid matrix.•Lettuce grown in an urban area on clean substrate is within health safety limits.
Extractive tests for determining the plant-availability of soil phosphorus (P) give varying results due to the inherently different characteristics of the extraction solution. Generally, classical ...soil P tests such as the Olsen or calcium acetate/lactate (CAL) method do not give an indication on the total amount of plant available P, but merely give an indication of the equilibrium between soil and extraction solution. It is also not entirely clear which fractions of P are directly determined through the various methods of extraction, i.e., determined P must not be immediately plant available, as is the case for rock phosphate. It is therefore possible that extraction methods either over or under estimate the amount of P available for plant consumption. In this research, we compared three methods of soil P determination (CAL, Olsen and diffusive gradients in thin films (DGT)) with regards to their ability to determine P species (Ca(H2PO4)2, CaHPO4, Ca3(PO4)2 and Inositol-6-hexakisphosphate) added to soils of high sorption capacity, immediately after as well as two weeks after application. For each of the methods, it could be shown that sorption processes in the soil immediately (0 days incubation) fix P to a point where it is not extractable through any of the described methods. These sorption processes continue over time, leading to a further decrease of determined P. The acidic CAL extraction method gives higher results of extractable P compared to the Olsen method. Due to the extraction of Ca3(PO4)2, the CAL method may overestimate immediately plant-available P. The most suitable methods for the determination of immediately plant available P may therefore be the Olsen and DGT methods. Organic IP6 is not determined by any of the extraction methods. At low concentrations of soil P, the DGT method may fail to give results.
Recovering and recycling phosphorus (P) from sewage sludge ash (SSA) for the purpose of P fertilizer production contributes to reducing the input of mined phosphate-minerals and closing of the P ...cycle. However, direct use of SSA as fertilizer is often a questionable strategy due to its low nutrient use efficiency. In addition, the environmental risk potential of utilizing SSA in agriculture is still unclear, in particular potential toxic element (PTE) contamination. In this study, a mixture of SSA and rock phosphate was used at lab-scale superphosphate (SP) production. P availability of the final product and PTE contamination (Cd, Cr, Cu, Zn, Pb, Ni) in soil and crop was investigated through maize (Zea mays L.) cultivation. Results showed that the application of SP that was produced by 25% SSA replacement did not affect the growth, P uptake, and PTE content in aboveground maize compared to the application of SP produced without SSA replacement. However, significant inputs of SP with SSA replacement may decrease the solid-soil solution partitioning of Cu, Ni and Pb in the long-term. Separation of municipal/industrial sludge and PTE removal technology are necessary to be implemented prior to the use of SSA as a secondary raw material in P-fertilizer production.
Nanozymes have emerged as a new generation of antibiotics with exciting broad‐spectrum antimicrobial properties and negligible biotoxicities. However, their antibacterial efficacies are ...unsatisfactory due to their inability to trap bacteria and their low catalytic activity. Herein, we report nanozymes with rough surfaces and defect‐rich active edges. The rough surface increases bacterial adhesion and the defect‐rich edges exhibit higher intrinsic peroxidase‐like activity compared to pristine nanozymes due to their lower adsorption energies of H2O2 and desorption energy of OH*, as well as the larger exothermic process for the whole reaction. This was demonstrated using drug‐resistant Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus in vitro and in vivo. This strategy can be used to engineer nanozymes with enhanced antibacterial function and will pave a new way for the development of alternative antibiotics.
Defect‐rich, adhesive nanozymes: A rough surface endows nanozymes with the ability to trap bacteria and defect‐rich edges enhance their peroxidase‐like activity, increasing antibacterial activity in comparison to pristine nanozymes.
Sepsis, characterized by immoderate production of multiple reactive oxygen and nitrogen species (RONS), causes high morbidity and mortality. Despite progress made with nanozymes, efficient ...antioxidant therapy to eliminate these RONS remains challenging, owing largely to the specificity and low activity of exploited nanozymes. Herein, an enzyme‐mimicking single‐atom catalyst, Co/PMCS, features atomically dispersed coordinatively unsaturated active Co‐porphyrin centers, which can rapidly obliterate multiple RONS to alleviate sepsis. Co/PMCS can eliminate O2.− and H2O2 by mimicking superoxide dismutase, catalase, and glutathione peroxidase, while removing .OH via the oxidative‐reduction cycle, with markedly higher activity than nanozymes. It can also scavenge .NO through formation of a nitrosyl–metal complex. Eventually, it can reduce proinflammatory cytokine levels, protect organs from damage, and confer a distinct survival advantage to the infected sepsis mice.
Better than nanozymes: By mimicking triple antioxidant enzymes, conducting an oxidative‐reduction cycle, and formation of a nitrosyl–metal complex, an enzyme‐mimicking single‐atom catalyst (SAzyme) can quickly obliterate multiple reactive oxygen and nitrogen species (RONS) and reduce proinflammatory cytokine levels to alleviate sepsis.
The insufficient intracellular H2O2 level in tumor cells is closely associated with the limited efficacy of chemodynamic therapy (CDT). Despite tremendous efforts, engineering CDT agents with a ...straightforward and secure H2O2 supplying ability remains a great challenge. Inspired by the balance of H2O2 generation and elimination in cancer cells, herein, a nanozyme-based H2O2 homeostasis disruptor is fabricated to elevate the intracellular H2O2 level through facilitating H2O2 production and restraining H2O2 elimination for enhanced CDT. In the formulation, the disruptor with superoxide dismutase-mimicking activity can convert O2 •– to H2O2, promoting the production of H2O2. Simultaneously, the suppression of catalase activity and depletion of glutathione by the disruptor weaken the transformation of H2O2 to H2O. Thus, the well-defined system could perturb the H2O2 balance and give rise to the accumulation of H2O2 in cancer cells. The raised H2O2 level would ultimately amplify the Fenton-like reaction-based CDT efficiency. Our work not only paves a way to engineer alternative CDT agents with a H2O2 supplying ability for intensive CDT but also provides new insights into the construction of bioinspired materials.
As one of the most typical bioorthogonal reactions, the Cu(I)-catalyzed azide–alkyne 1,3-cycloaddition (CuAAC) reaction has received worldwide attention in intracellular transformation of prodrugs ...due to its high efficiency and selectivity. However, the exogenous Cu catalysts may disturb Cu homeostasis and cause side effects to normal tissues. What is more, the intratumoral Cu(I) is insufficient to efficiently catalyze the intracellular CuAAC reaction due to oncogene-induced labile Cu(I) deficiency. Herein, in order to boost the endogenous Cu(I) level for intracellular drug synthesis through the bioorthogonal reaction, a self-adaptive bioorthogonal catalysis system was constructed by encapsulating prodrugs and sodium ascorbate within adenosine triphosphate aptamer-functionalized metal–organic framework nanoparticles. The system presents specificity to tumor cells and does not require exogenous Cu catalysts, thereby leading to high anti-tumor efficacy and minimal side effects both in vitro and in vivo. This work will open up a new opportunity for developing biosafe and high-performance bioorthogonal catalysis systems.
PDF
