A Fe(III) intercalated clay nanoplatform for combined chemo/chemodynamic therapy.

A Fe(III) intercalated montmorillonite nanoplatform (Fe-MMT) was engineered for doxorubicin (DOX) loading. The constructed Fe-MMT/DOX nanoplatform could not only improve the production of H2O2 to enhance chemodynamic therapy but interfere with DNA damage repair to amplify the efficacy of DOX, proving an ideal combination of chemotherapy and chemodynamic therapy.

In Vitro Binding and Release Mechanisms of Doxorubicin from Nanoclays.

Nanoclays have been developed as drug delivery systems, but their mechanisms of DOX delivery are unclear. Herein, unmodified nanoclays (halloysite, kaolinite, montmorillonite) were comprehensively studied on their in vitro binding and release mechanisms of DOX from both experimental and theoretical aspects. These nanoclays with high loading capacity (>50%) and encapsulation efficiency capacity (>90%) of DOX are attributed to the exposed hydroxyl groups and the Lewis base sites on the surfaces. Density functional theory calculations also confirmed that DOX is preferentially adsorbed on the Al-OH surfaces while adsorption on Si-O surfaces is limited. Besides this, the pH-responsive profiles of DOX release from nanoclays are related to the protonation of negatively charged nanoclays in weakly acidic solutions that makes it easier to dissociate with positively charged DOX. The in-depth mechanistic method in this work is widely applicable and demonstrates that nanoclays can be used as efficient nanocarriers for more biomedical applications.

The Optimization of the Transition Zone of the Planar Heterogeneous Interface for High-Performance Seawater Desalination.

Reverse osmosis has become the most prevalent approach to seawater desalination. It is still limited by the permeability-selectivity trade-off of the membranes and the energy consumption in the operation process. Recently, an efficient ionic sieving with high performance was realized by utilizing the bi-unipolar transport behaviour and strong ion depletion of heterogeneous structures in 2D materials. A perfect salt rejection rate of 97.0% and a near-maximum water flux of 1529 L m-2 h-1 bar-1 were obtained. However, the energy consumption of the heterogeneous desalination setup is a very important factor, and it remains largely unexplored. Here, the geometric-dimension-dependent ion transport in planar heterogeneous structures is reported. The two competitive ion migration behaviours during the desalination process, ion-depletion-dominated and electric-field-dominated ion transport, are identified for the first time. More importantly, these two ion-transport behaviours can be regulated. The excellent performance of combined high rejection rate, high water flux and low energy consumption can be obtained under the synergy of voltage, pressure and geometric dimension. With the appropriate optimization, the energy consumption can be reduced by 2 orders of magnitude, which is 50% of the industrial energy consumption. These findings provide beneficial insight for the application and optimized design of low-energy-consumption and portable water desalination devices.

Polypeptide-based drug delivery systems for programmed release.

Recent years have seen increasing interests in the use of ring-opening polymerization of α-amino acid N-carboxyanhydrides (NCAs) to prepare synthetic polypeptides, a class of biocompatible and versatile materials, for various biomedical applications. Because of their rich side-chain functionalities, diverse hydrophilicity/hydrophobicity profiles, and the capability of forming stable secondary structures, polypeptides can assemble into a variety of well-organized nano-structures that have unique advantages in drug delivery and controlled release. Herein, we review the design and use of polypeptide-based drug delivery system derived from NCA chemistry, and discuss the future perspectives of this exciting and important biomaterial area that may potentially change the landscape of next-generation therapeutics and diagnosis. Given the high significance of precise control over release for polypeptide-based systems, we specifically focus on the versatile designs of drug delivery systems capable of programmed release, through the changes in the chemical and physical properties controlled by the built-in molecular structures of polypeptides.

Machine Learning-Based Modeling of Spatio-Temporally Varying Responses of Rainfed Corn Yield to Climate, Soil, and Management in the U.S. Corn Belt.

Better understanding the variabilities in crop yield and production is critical to assessing the vulnerability and resilience of food production systems. Both environmental (climatic and edaphic) conditions and management factors affect the variabilities of crop yield. In this study, we conducted a comprehensive data-driven analysis in the U.S. Corn Belt to understand and model how rainfed corn yield is affected by climate variability and extremes, soil properties (soil available water capacity, soil organic matter), and management practices (planting date and fertilizer applications). Exploratory data analyses revealed that corn yield responds non-linearly to temperature, while the negative vapor pressure deficit (VPD) effect on corn yield is monotonic and more prominent. Higher mean yield and inter-annual yield variability are found associated with high soil available water capacity, while lower inter-annual yield variability is associated with high soil organic matter (SOM). We also identified region-dependent relationships between planting date and yield and a strong correlation between planting date and the April weather condition (temperature and rainfall). Next, we built machine learning models using the random forest and LASSO algorithms, respectively, to predict corn yield with all climatic, soil properties, and management factors. The random forest model achieved a high prediction accuracy for annual yield at county level as early as in July (R 2 = 0.781) and outperformed LASSO. The gained insights from this study lead to improved understanding of how corn yield responds to climate variability and projected change in the U.S. Corn Belt and globally.

Improving the Physical-Mechanical Property of Dental Composites by Grafting Methacrylate-Polyhedral Oligomeric Silsesquioxane onto a Filler Surface.

Endowing dental composites with excellent interfacial bonding through filler surface modification is pivotal to improve the physical-mechanical property and prolong the life of composite fillings. In this study, methacrylate-polyhedral oligomeric silsesquioxane (MA-POSS) acts as a "molecular bridge" between the commonly used SiO2 particles and the methacrylate-based resin matrix via a thiol-ene click reaction to construct MA-POSS/SiO2 (p-SiO2) hybrid particles. Synthesized p-SiO2 exhibited the roughest surface morphology and had more polymerizable groups, in comparison with SiO2 and silanized SiO2. Furthermore, the p-SiO2 particles were used as a reinforcement to fabricate bisphenol A glycerolate dimethacrylate/tri(ethyleneglycol) dimethacrylate-based dental composites, where the SiO2- and silanized SiO2-filled composites served as the control groups, and the filler loading was fixed at 65 wt %. Results of the mechanical properties indicated that the hybrid p-SiO2 particles significantly improved the flexural strength, flexural modulus, compressive strength, and work of fracture of dental composites, giving improvements of 251.2, 17.89, 122.3, and 1094%, respectively, over the SiO2-filled composites due to the strong interfacial interaction between the resin matrix and p-SiO2. Additionally, this optimal p-SiO2-loaded composite also presented better polymerization shrinkage, acceptable degree of conversion, curing depth, and cell viability. Grafting of MA-POSS onto a filler surface is a promising filler surface modification to improve the resin matrix/filler interfacial interaction, leading to the enhanced overall performance of composites.

Accelerated polymerization of N-carboxyanhydrides catalyzed by crown ether.

The recent advances in accelerated polymerization of N-carboxyanhydrides (NCAs) enriched the toolbox to prepare well-defined polypeptide materials. Herein we report the use of crown ether (CE) to catalyze the polymerization of NCA initiated by conventional primary amine initiators in solvents with low polarity and low hydrogen-bonding ability. The cyclic structure of the CE played a crucial role in the catalysis, with 18-crown-6 enabling the fastest polymerization kinetics. The fast polymerization kinetics outpaced common side reactions, enabling the preparation of well-defined polypeptides using an α-helical macroinitiator. Experimental results as well as the simulation methods suggested that CE changed the binding geometry between NCA and propagating amino chain-end, which promoted the molecular interactions and lowered the activation energy for ring-opening reactions of NCAs. This work not only provides an efficient strategy to prepare well-defined polypeptides with functionalized C-termini, but also guides the design of catalysts for NCA polymerization.

[Research on rhizospheric and endophytic actinomycetes in medicinal tree peony(Paeonia suffruticosa) from five producing regions].

In this study, Paeonia suffruticosa roots and rhizospheric soil in five geographic regions which were harvested in October were utilized as experimental materials, then the diversity of endophytic and rhizospheric actinomycetes were investigated by High-throughput sequencing technique. The 1 754 operational taxonomic units (OTUs) were obtained from 129 954 high quality sequences, 1 311 OTUs were detected in rhizospheric actinomycetes and belonged to four classes, four orders, twenty-seven families and ninety-seven genera, thirty-three genera such as Ilumatobacter were found in the five regions rhizospheric soil while three genera such as Longispora were only detected in the Dao-di regions, the dominant genera were Mycobacterium, Nocardioides, Streptomyces. 443 OTUs were obtained in roots and distributed in three classes, three orders, twenty-four families and fifty genera, thirteen genera such as Cryptosporangium were found in the five regions roots while Planosporangium, Luteococcus were only detected in the Dao-di regions, the dominant genera were Nocardioides. Alpha diversity analysis showed that the Shannon and Chao1 index in rhizospheric actinomycetes in Bozhou, Tongling and Nanling region were higher than Heze and Luoyang. Based on principal co-ordinates analysis (PCoA) analysis, the rhizospheric actinomycetes formations were similar in Tongling and Nanling region, at the same in Tongling and Luoyang endophytic actinomycetes. According to heatmap analysis, Bozhou, Tongling and Nanling region rhizospheric actinomycetes showed a close similarity in actinomycetes community structures on phylogenetic analysis, while Tongling, Luoyang and Nanling endophytic actinomycetes showed the same. Our results not only suggested that the rich and diverse actinomycetes resources in P. suffruticosa roots and rhizospheric soil but also revealed rhizospheric actinomycetes in the Dao-di regions had high similarity.