Recent advancements in drug delivery technologies utilizing a variety of carriers have resulted in a path-breaking revolution in the approach towards diagnosis and therapy alike in the current times. Need for materials with high thermal, chemical and mechanical properties have led to the development of mesoporous silica nanoparticles (MSNs). These ordered porous materials have garnered immense attention as drug carriers owing to their distinctive features over the others. They can be synthesized using a relatively simple process, thus making it cost effective. Moreover, by controlling the parameters during the synthesis; the morphology, pore size and volume and particle size can be transformed accordingly. Over the last few years, a rapid increase in research on MSNs as drug carriers for the treatment of various diseases has been observed indicating its potential benefits in drug delivery. Their widespread application for the loading of small molecules as well as macromolecules such as proteins, siRNA and so forth, has made it a versatile carrier. In the recent times, researchers have sorted to several modifications in the framework of MSNs to explore its potential in drug resistant chemotherapy, antimicrobial therapy. In this review, we have discussed the synthesis of these multitalented nanoparticles and the factors influencing the size and morphology of this wonder carrier. The second part of this review emphasizes on the applications and the advances made in the MSNs to broaden the spectrum of its use especially in the field of biomedicine. We have also touched upon the lacunae in the thorough understanding of its interaction with a biological system which poses a major hurdle in the passage of this carrier to the clinical level. In the final part of this review, we have discussed some of the major patents filed in the field of MSNs for therapeutic purpose.

https://www.mdpi.com/1999-4923/10/3/118/pdf/1

Mesoporous Silica Nanoparticles: A Comprehensive Review on Synthesis and Recent Advances

Microbes play a critical role in soil global biogeochemical circulation and microbe-microbe interactions have also evoked enormous interests in recent years. Utilization of green manures can stimulate microbial activity and affect microbial composition and diversity. However, few studies focus on the microbial interactions or detect the key functional members in communities. With the advances of metagenomic technologies, network analysis has been used as a powerful tool to detect robust interactions between microbial members. Here, random matrix theory-based network analysis was used to investigate the microbial networks in response to four different green manure fertilization regimes (Vicia villosa, common vetch, milk vetch, and radish) over two growth cycles from October 2012 to September 2014. The results showed that the topological properties of microbial networks were dramatically altered by green manure fertilization. Microbial network under milk vetch amendment showed substantially more intense complexity and interactions than other fertilization systems, indicating that milk vetch provided a favorable condition for microbial interactions and niche sharing. The shift of microbial interactions could be attributed to the changes in some major soil traits and the interactions might be correlated to plant growth and production. With the stimuli of green manures, positive interactions predominated the network eventually and the network complexity was in consistency with maize productivity, which suggested that the complex soil microbial networks might benefit to plants rather than simple ones, because complex networks would hold strong the ability to cope with environment changes or suppress soil-borne pathogen infection on plants. In addition, network analyses discerned some putative keystone taxa and seven of them had directly positive interactions with maize yield, which suggested their important roles in maintaining environmental functions and in improving plant growth.

Integrated network analysis reveals the importance of microbial interactions for maize growth

Elevated soil loss and runoff rates can reduce soil fertility; therefore, soil erosion control strategies must be implemented at the hillslope and watershed scale when plantations are established and the soil is bare. In this research, we propose the use of the Vicia sativa Roth. to reduce the soil losses during the first year to control the peak of soil erosion after the plantation in tilled vineyards. To test its efficiency, rainfall simulation experiments were carried out with field surveys in The Casa Pago Gran, in the Eastern Iberian Peninsula. Our results demonstrate that soil properties (organic matter and soil bulk density) and soil erosion (soil loss, runoff and sediment concentration) were significantly different between the control plot (tilled) and with cover crops along with August 2016, 2017 and 2018 measurement periods, but not during January 2016, coinciding with the initial survey before the vetch sown. Runoff initiation was delayed in 3.7 times after 3 years (from 190 till 709 s). The runoff discharge was reduced by the Vicia sativa from 32.87 till 13.68%, the sediment concentration went down from 18.54 till 3.81 gr l−1 and the soil erosion from 3.36 to 0.29 Mg ha−1 year−1. An increase in soil bulk density was registered but did not affect the runoff generation either the soil losses, that was reduced by the plant cover. We conclude that it is necessary to include soil erosion control measures such as the use of Vicia sativa to reduce soil erosion processes during the first stages of the vineyard plantations due to the soil quality improvements and the reduction in soil and water losses.

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Vicia sativa Roth. Can Reduce Soil and Water Losses in Recently Planted Vineyards (Vitis vinifera L.)

The present study describes the preparation and characterization of montmorillonite-urea nanocomposites (Mt-Ur) using aqueous suspension technique at various stirring times and different ratio of montmorillonite to urea (Mt/Ur) via an impure and domestic montmorillonite (Mt), without the application of any chemical reagents and high-energy-demand process (environmentally friendly). The intercalation of urea into Mt interlayer was clearly demonstrated by a significant expansion of d001 spacing (interlayer space of Mt) from 1.23 to 1.71 nm which has not yet been reported by aqueous suspension technique. Analyses performed by Fourier transform-infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) also confirmed the effectiveness of this simple process to intercalate the urea into clay lamella. The release pattern demonstrated that the nanocomposite had a slow-release behaviour for urea dissolution. The results also suggested that the Mt type applied in the curren...

Synthesis of highly intercalated urea-clay nanocomposite via domestic montmorillonite as eco-friendly slow-release fertilizer

Novel synthesis of layered double hydroxides (LDHs) from zinc hydroxide

A general stoichiometric cation exchange mechanism does not fully explain the unique exchange behaviors of Na-4-mica, the most highly charged swelling 2:1 phyllosilicate. Herein, we present for the first time a novel model of hydronium-promoted equilibrium for the cation exchange reaction of highly charged swelling 2:1 phyllosilicates with alkali metal cations. The exchange reaction of Na-4-mica with alkali metal cations revealed that adsorbed cations undergo further exchange with hydronium ions to result in the unprecedented back-release and position rearrangement of adsorbed cations. During the exchange reaction, hydronium ions play a key role as not competitive but stabilizing cation. Stabilization is accomplished through replacing half of the adsorbed cations and consequently relocating their position. Therefore, this hydronium-promoted equilibrium mechanism would provide a novel intellectual framework not only for understanding cation exchange reactions of various highly charged phyllosilicates but a...

Hydronium-Promoted Equilibrium Mechanism for the Alkali Metal Cation Exchange Reaction in Na-4-Mica

Purpose
A large amount of nitrogen (N) fertilizers has been broadcasted over soil surface for reliable crop production. Unfortunately, the broadcasted N vulnerable to volatilization and leaching can lead to serious environmental problems. As a new approach to mitigate N loss of broadcasted fertilizers, massive intercalation of urea into montmorillonite (MMT) was recently proposed to innovatively enhance the urea use efficiency. This study focuses on demonstrating the behaviors of the urea intercalated into MMT in soils.

Suppression of NH3 and N2O emissions by massive urea intercalation in montmorillonite

Massive Intercalation of Urea in Montmorillonite

Novel behaviors such as adsorbate-dependent pore opening and functionality-controlled uptake have been accomplished by the bifunctionalized ordered mesoporous silica developed here. SBA-11 was topographically functionalized with two different functional groups by step-wise functionalization. Bulky and flexible tert-butylphenethyl (BP) groups were topographically grafted around the pore entrance and on the external surface, while small dimethyl (DM) groups were attached on the inner pore surface. The resulting bifunctionalized SBA-11 exhibited the selective malathion scavenger, which was not observed by the corresponding mono-functionalized SBA-11s. The uptake behaviors of the functionalized SBA-11s for malathion and toluene strongly suggest that the bulky and flexible BP groups are locally grafted around the pore entrance to act as a functional pore window. The interaction among the adsorbate, BP and DM groups induces a specific rearrangement of functional pore window which leads to the discriminative uptake. Therefore, the functionalized OMMs equipped with the pore window, the nanosized functional vessels, could be developed into the adsorbate-discriminating adsorbents for highly selective removal/recovery of specific organic molecules.

Adsorbate-dependent uptake behavior of topographically bi-functionalized ordered mesoporous silica materials

Isomorphic substitution, position replacement of one cation by another of similar size, leads to incorporation of a variety of cations into solid crystals without any significant changes to the primary crystal structures. To date, isomorphic substitution has been known to take place almost exclusively via co-crystallization of the cations during formation of the crystals. We report here the discovery of isomorphic substitution of trivalent metal cations for Ca2+ ions in portlandite crystals at room temperature as evidenced by the transient appearance of metastable phase, the formation of Ca-based layered double hydroxides at high pH, the distinct shift of suspension pH after phase transition, and the in situ topochemical reaction. This post-crystallization isomorphic substitution provides an innovative pathway for the synthesis of materials through chemical manipulation of crystals as well as a new insight into interpretation on their weathering and transformation processes.

Kwang Seop Kim

Papers

Hydronium-Promoted Equilibrium Mechanism for the Alkali Metal Cation Exchange Reaction in Na-4-Mica

Suppression of NH3 and N2O emissions by massive urea intercalation in montmorillonite

Massive Intercalation of Urea in Montmorillonite

Adsorbate-dependent uptake behavior of topographically bi-functionalized ordered mesoporous silica materials

Post-isomorphic substitution of trivalent metal cations for Ca2+ in portlandite crystals