Advances in nanoparticle and organic formulations for prolonged controlled release of auxins.

Plant hormones have been well known since Charles Darwin as signaling molecules directing plant metabolism. Their action and transport pathways are at the top of scientific interest and were reviewed in many research articles. Modern agriculture applies phytohormones as supplements to achieve desired physiological plant response. Auxins are a class of plant hormones extensively used for crop management. Auxins stimulate the formation of lateral roots and shoots, seed germination, while extensively high concentrations of these chemicals act as herbicides. Natural auxins are unstable; light or enzyme action leads to their degradation. Moreover, the concentration dependant action of phytohormones denier one-shot injection of these chemicals and require constant slow additive of supplement. It obstructs the direct introduction of auxins. On the other hand, delivery systems can protect phytohormones from degradation and provide a slow release of loaded drugs. Moreover, this release can be managed by external stimuli like pH, enzymes, or temperature. The present review is focused on three auxins: indole-3-acetic, indole-3-butyric, and 1-naphthaleneacetic acids. We collected some examples of inorganic (oxides, Ag, layered double hydroxides) and organic (chitosan, organic formulations) delivery systems. The action of carriers can enhance auxin effects via protection and targeted delivery of loaded molecules. Moreover, nanoparticles can act as nano fertilizers, intensifying the phytohormone effect, providing slow controlled release. So delivery systems for auxins are extremely attractive for modern agriculture opening sustainable management of plant metabolism and morphogenesis.

In Situ FTIR Spectroscopy for Scanning Accessible Active Sites in Defect-Engineered UiO-66.

Three UiO-66 samples were prepared by solvothermal synthesis using the defect engineering approach with benzoic acid as a modulator. They were characterized by different techniques and their acidic properties were assessed by FTIR spectroscopy of adsorbed CO and CD3CN. All samples evacuated at room temperature contained bridging µ3-OH groups that interacted with both probe molecules. Evacuation at 250 °C leads to the dehydroxylation and disappearance of the µ3-OH groups. Modulator-free synthesis resulted in a material with open Zr sites. They were detected by low-temperature CO adsorption on a sample evacuated at 200 °C and by CD3CN even on a sample evacuated at RT. However, these sites were lacking in the two samples obtained with a modulator. IR and Raman spectra revealed that in these cases, the Zr4+ defect sites were saturated by benzoates, which prevented their interaction with probe molecules. Finally, the dehydroxylation of all samples produced another kind of bare Zr sites that did not interact with CO but formed complexes with acetonitrile, probably due to structural rearrangement. The results showed that FTIR spectroscopy is a powerful tool for investigating the presence and availability of acid sites in UiO-66, which is crucial for its application in adsorption and catalysis.

Nanoparticles-Based Delivery Systems for Salicylic Acid as Plant Growth Stimulator and Stress Alleviation.

The population growth tendency leads to an increase in demand for food products, and in particular, products obtained from the processing of plants. However, there are issues of biotic and abiotic stresses that can significantly reduce crop yields and escalate the food crisis. Therefore, in recent years, the development of new methods of plant protection became an important task. One of the most promising ways to protect plants is to treat them with various phytohormones. Salicylic acid (SA) is one of the regulators of systemic acquired resistance (SAR) signaling pathways. These mechanisms are able to protect plants from biotic and abiotic stresses by increasing the expression of genes that encode antioxidant enzymes. However, salicylic acid in high doses can act as an antagonist and have the negative rebound effect of inhibition of plant growth and development. To maintain optimal SA concentrations in the long term, it is necessary to develop systems for the delivery and slow release of SA in plants. The purpose of this review is to summarize and study methods of delivery and controlled release of SA in a plant. Various carriers-based nanoparticles (NPs) synthesized from both organic and inorganic compounds, their chemical structure, impacts on plants, advantages, and disadvantages are comprehensively discussed. The mechanisms of controlled release of SA and the effects of the use of the considered composites on the growth and development of plants are also described. The present review will be helpful to design or fabricate NPs and NPs-based delivery systems for salicylic acid-controlled release and better understating of the mechanism of SA-NPs interaction to alleviate stress on plants.

Fabrication of biochar derived from different types of feedstocks as an efficient adsorbent for soil heavy metal removal.

For effective soil remediation, it is vital to apply environmentally friendly and cost-effective technologies following the notion of green sustainable development. In the context of recycling waste and preserving nutrients in the soil, biochar production and utilization have become widespread. There is an urgent need to develop high-efficiency biochar-based sorbents for pollution removal from soil. This research examined the efficacy of soil remediation using biochar made from three distinct sources: wood, and agricultural residues (sunflower and rice husks). The generated biochars were characterized by SEM/SCEM, XRF, XRD, FTIR, BET Specific Surface Area, and elemental compositions. The presence of hydroxyl and phenolic functional groups and esters in wood, sunflower and rice husk biochar were noted. The total volume of pores was in the following descending order: rice husk > wood > sunflower husk. However, wood biochar had more thermally stable, heterogeneous, irregular-shaped pores than other samples. Adsorption of soil-heavy metals into biochars differed depending on the type of adsorbent, according to data derived from distribution coefficients, sorption degree, Freundlich, and Langmuir adsorption models. The input of biochars to Calcaric Fluvic Arenosol increased its adsorption ability under contamination by Cu(II), Zn(II), and Pb(II) in the following order: wood > rice husk > sunflower husk. The addition of sunflower husk, wood, and rice husk biochar to the soil led to an increase in the removal efficiency of metals in all cases (more than 77%). The increase in the percentage adsorption of Cu and Pb was 9-19%, of Zn was 11-21%. The present results indicated that all biochars functioned well as an absorbent for removing heavy metals from soils. The tailor-made surface chemistry properties and the high sorption efficiency of the biochar from sunflower and rice husks could potentially be used for soil remediation.

Application of Artificial Intelligence at All Stages of Bone Tissue Engineering.

The development of artificial intelligence (AI) has revolutionized medical care in recent years and plays a vital role in a number of areas, such as diagnostics and forecasting. In this review, we discuss the most promising areas of AI application to the field of bone tissue engineering and prosthetics, which can drastically benefit from AI-assisted optimization and patient personalization of implants and scaffolds in ways ranging from visualization and real-time monitoring to the implantation cases prediction, thereby leveraging the compromise between specific architecture decisions, material choice, and synthesis procedure. With the emphasized crucial role of accuracy and robustness of developed AI algorithms, especially in bone tissue engineering, it was shown that rigorous validation and testing, demanding large datasets and extensive clinical trials, are essential, and we discuss how through developing multidisciplinary cooperation among biology, chemistry with materials science, and AI, these challenges can be addressed.

Doxorubicin-Loaded Core-Shell UiO-66@SiO2 Metal-Organic Frameworks for Targeted Cellular Uptake and Cancer Treatment.

Beneficial features of biocompatible high-capacity UiO-66 nanoparticles, mesoporous SiO2, and folate-conjugated pluronic F127 were combined to prepare the core-shell UiO-66@SiO2/F127-FA drug delivery carrier for targeted cellular uptake in cancer treatment. UiO-66 and UiO-66-NH2 nanoparticles with a narrow size and shape distribution were used to form a series of core-shell MOF@SiO2 structures. The duration of silanization was varied to change the thickness of the SiO2 shell, revealing a nonlinear dependence that was attributed to silicon penetration into the porous MOF structure. Doxorubicin encapsulation showed a similar final loading of 5.6 wt % for both uncoated and silica-coated particles, demonstrating the potential of the nanocomposite's application in small molecule delivery. Silica coating improved the colloidal stability of the composites in a number of model physiological media, enabled grafting of target molecules to the surface, and prevented an uncontrolled release of their cargo, with the drawback of decreased overall porosity. Further modification of the particles with the conjugate of pluronic and folic acid was performed to improve the biocompatibility, prolong the blood circulation time, and target the encapsulated drug to the folate-expressing cancer cells. The final DOX-loaded UiO-66@SiO2/F127-FA nanoparticles were subjected to properties characterization and in vitro evaluation, including studies of internalization into cells and antitumor activity. Two cell lines were used: MCF-7 breast cancer cells, which have overexpressed folate receptors on the cell membranes, and RAW 264.7 macrophages without folate overexpression. These findings will provide a potential delivery system for DOX and increase the practical value of MOFs.

Rational Functionalization of UiO-66 with Pd Nanoparticles: Synthesis and In Situ Fourier-Transform Infrared Monitoring.

Functionalization of metal-organic frameworks (MOFs) with noble metal nanoparticles (NPs) is a challenging task. Conventional impregnation by metals often leads to agglomerates on the surface of MOF crystals. Functional groups on linkers interact with metal precursors and promote the homogeneous distribution of NPs in the pores of MOFs, but their uncontrolled localization can block channels and thus hinder mass transport. To overcome this problem, we created nucleation centers only in the defective pores of the UiO-66 MOF via the postsynthesis exchange. First, we have introduced defects into UiO-66 using benzoic acid as a modulator. Second, the modulator was exchanged for amino-benzoic acid. As a result, amino groups have decorated mainly the defective pores and attracted the Pd precursor after impregnation. The interaction of the metal precursor with amino groups and the growth of NPs were monitored by in situ infrared spectroscopy. Three processes were distinguished: the gaseous HCl release, NH2 reactivation, and growth of extended Pd surfaces. Uniform Pd NPs were located in the pores because of the homogeneous distribution of the precursor and pore diffusion-limited nucleation rate. Our work demonstrates an alternative approach of controlled Pd incorporation into UiO-66 that is of great importance for the rational design of heterogeneous catalysts.

The Rare-Earth Elements Doping of BaGdF5 Nanophosphors for X-ray Photodynamic Therapy.

It is known that the initiation of photodynamic therapy (PDT) in deep-seated tumors requires the use of X-rays to activate the reactive oxygen species generation in deep tissues. The aim of this paper is to synthesize X-ray nanophosphors and analyze their structural and luminescence characteristics to push the PDT process deep into the body. The article deals with BaGdF5:Eu3+, BaGdF5:Sm3+, and BaGdF5:Tb3+ nanophosphors synthesized using microwave synthesis. It is found that the nanoparticles are biocompatible and have sizes 5-17 nm. However, according to the analysis of X-ray excited optical luminescence, BaGdF5:Sm3+ nanophosphors will not be effective for treating deep-seated tumors. Thus, BaGdF5:Eu3+ and BaGdF5:Tb3+ nanoparticles meet the requirements for the subsequent production of nanocomposites based on them that can be used in X-ray photodynamic therapy.

BaGdF5 Nanophosphors Doped with Different Concentrations of Eu3+ for Application in X-ray Photodynamic Therapy.

X-ray photodynamic therapy (XPDT) has been recently considered as an efficient alternative to conventional radiotherapy of malignant tissues. Nanocomposites for XPDT typically consist of two components-a nanophosphor which re-emits X-rays into visible light that in turn is absorbed by the second component, a photosensitizer, for further generation of reactive oxygen species. In this study, BaGdF5 nanophosphors doped with different Eu:Gd ratios in the range from 0.01 to 0.50 were synthesized by the microwave route. According to transmission electron microscopy (TEM), the average size of nanophosphors was ~12 nm. Furthermore, different coatings with amorphous SiO2 and citrates were systematically studied. Micro-CT imaging demonstrated superior X-ray attenuation and sufficient contrast in the liver and the spleen after intravenous injection of citric acid-coated nanoparticles. In case of the SiO2 surface, post-treatment core-shell morphology was verified via TEM and the possibility of tunable shell size was reported. Nitrogen adsorption/desorption analysis revealed mesoporous SiO2 formation characterized by the slit-shaped type of pores that should be accessible for methylene blue photosensitizer molecules. It was shown that SiO2 coating subsequently facilitates methylene blue conjugation and results in the formation of the BaGdF5: 10% Eu3+@SiO2@MB nanocomposite as a promising candidate for application in XPDT.

Photoswitchable Zirconium MOF for Light-Driven Hydrogen Storage.

Here, we report a new photosensitive metal-organic framework (MOF) that was constructed via the modification of UiO-66-NH2 with diarylethene molecules (DAE, 4-(5-Methoxy-1,2-dimethyl-1H-indol-3-yl)-3-(2,5-dimethylthiophen-3-yl)-4-furan-2,5-dione). The material that was obtained was a highly crystalline porous compound. The photoresponse of the modified MOF was observed via UV-Vis and IR spectroscopy. Most of the DAE molecules inside of the UiO-66-pores had an open conformation after synthesis. However, the equilibrium was able to be shifted further toward an open conformation using visible light irradiation with a wavelength of 520 nm. Conversely, UV-light with a wavelength of 450 nm initiated the transformation of the photoresponsive moieties inside of the pores to a closed modification. We have shown that this transformation could be used to stimulate hydrogen adsorption-desorption processes. Specifically, visible light irradiation increased the H2 capacity of modified MOF, while UV-light decreased it. A similar hybrid material with DAE moieties in the UiO-66 scaffold was applied for hydrogen storage for the first time. Additionally, the obtained results are promising for smart H2 storage that is able to be managed via light stimuli.

Microbial-based magnetic nanoparticles production: a mini-review.

The ever-increasing biomedical application of magnetic nanoparticles (MNPs) implies increasing demand in their scalable and high-throughput production, with finely tuned and well-controlled characteristics. One of the options to meet the demand is microbial production by nanoparticles-synthesizing bacteria. This approach has several benefits over the standard chemical synthesis methods, including improved homogeneity of synthesis, cost-effectiveness, safety and eco-friendliness. There are, however, specific challenges emanating from the nature of the approach that are to be accounted and resolved in each manufacturing instance. Most of the challenges can be resolved by proper selection of the producing organism and optimizing cell culture and nanoparticles extraction conditions. Other issues require development of proper continuous production equipment, medium usage optimization and precursor ions recycling. This mini-review focuses on the related topics in microbial synthesis of MNPs: producing organisms, culturing methods, nanoparticles characteristics tuning, nanoparticles yield and synthesis timeframe considerations, nanoparticles isolation as well as on the respective challenges and possible solutions.

Self-Driving Laboratories for Development of New Functional Materials and Optimizing Known Reactions.

Innovations often play an essential role in the acceleration of the new functional materials discovery. The success and applicability of the synthesis results with new chemical compounds and materials largely depend on the previous experience of the researcher himself and the modernity of the equipment used in the laboratory. Artificial intelligence (AI) technologies are the next step in developing the solution for practical problems in science, including the development of new materials. Those technologies go broadly beyond the borders of a computer science branch and give new insights and practical possibilities within the far areas of expertise and chemistry applications. One of the attractive challenges is an automated new functional material synthesis driven by AI. However, while having many years of hands-on experience, chemistry specialists have a vague picture of AI. To strengthen and underline AI's role in materials discovery, a short introduction is given to the essential technologies, and the machine learning process is explained. After this review, this review summarizes the recent studies of new strategies that help automate and accelerate the development of new functional materials. Moreover, automatized laboratories' self-driving cycle could benefit from using AI algorithms to optimize new functional nanomaterials' synthetic routes. Despite the fact that such technologies will shape material science in the nearest future, we note the intelligent use of algorithms and automation is required for novel discoveries.

Loading of the Model Amino Acid Leucine in UiO-66 and UiO-66-NH2: Optimization of Metal-Organic Framework Carriers and Evaluation of Host-Guest Interactions.

Two metal-organic frameworks (MOFs), UiO-66 and UiO-66-NH2, were considered as containers for bioactive chemicals. We provide a synthesis technique, which allowed the production of these materials suitable for biomedical applications. Both MOFs were characterized as single-phase porous materials composed of nanoparticles (30-65 nm) with a ζ-potential of more than 40 mV in water suspension. D,L-Leucine was applied as a model molecule, which allowed us to trace the mechanism of the loading process. We showed that after synthesis, amino groups of UiO-66-NH2 are coordinated with solvent residuals. It results in a similar route of leucine loading in UiO-66 and UiO-66-NH2 samples. Using joint data of thermogravimetric analysis and calorimetry, infrared spectroscopy, and nitrogen adsorption, we revealed that methyl groups of leucine molecules are responsible for bonding of an MOF matrix. We proposed the formation of bonds between CH3 groups and benzene rings of linkers via CH-π interaction. We also assessed the toxicity of the synthesized MOFs toward HeLa cells at 50 µg/mL after 24 h incubation and revealed no negative effects on the viability of the cells, prompting further biomedical research in the areas of small-molecule delivery and cell signaling and metabolism modulation.

Laboratory Operando XAS Study of Sodium Iron Titanite Cathode in the Li-Ion Half-Cell.

Electrochemical characterization of the novel sodium iron titanate Na0.9Fe0.45Ti1.55O4 was performed upon cycling in the Li-ion half-cell. The material exhibited stable cycling in the voltage range 2-4.5 V, and the number of alkali ions extracted per formula unit was approximately half of the Na stoichiometry value. Using laboratory X-ray absorption spectrometry, we measured operando Fe K-edge X-ray absorption spectra in the first 10 charge-discharge cycles and quantified the portion of charge associated with the transition metal redox reaction. Although 3d metals are commonly accepted redox-active centers in the intercalation process, we found that in all cycles the amount of oxidized and reduced Fe ions was almost 20% less than the total number of transferred electrons. Using density functional theory (DFT) simulations, we show that part of the reversible capacity is related to the redox reaction on oxygen ions.

ᶫ-Leucine Loading and Release in MIL-100 Nanoparticles.

Synthesis of the MIL-100 metal-organic framework particles was carried out by hydrothermal (HT) and microwave (MW)-assisted methods. Transmission electron microscopy showed formation of microparticles in the course of hydrothermal synthesis and nanoparticles for microwave-assisted synthesis. Powder X-ray diffraction confirmed formation of larger crystallites for hydrothermal synthesis. Particle aggregation in aqueous solution was observed by dynamic light scattering. However, the stability of both samples could be improved in acetic acid solution. Nitrogen sorption isotherms showed high porosity of the particles. ᶫ-leucine molecule was used as a model molecule for loading in the porous micro- and nanoparticles. Loading was estimated by FTIR spectroscopy and thermogravimetric analysis. UV-VIS spectroscopy quantified ᶫ-leucine release from the particles in aqueous solution. Cytotoxicity studies using the HeLa cell model showed that the original particles were somewhat toxic, but ᶫ-leucine loading ameliorated the toxic effects, likely due to signaling properties of the amino acid.

Pd nanoparticle growth monitored by DRIFT spectroscopy of adsorbed CO.

Synchrotron-based X-ray absorption spectroscopy and scattering are known in situ probes of metal nanoparticles (NPs). A limited number of laboratory techniques allow post-synthesis diagnostics of the active metal surface area. This work demonstrates the high potential of infrared spectroscopy as an in situ laboratory probe for the growth of metal NPs on a substrate. We introduce a small fraction of CO molecules into the reaction mixture as a probe to monitor the reduction kinetics of the Pd2+ precursor on ceria in hydrogen.

Immobilization of UiO-67 with photochromic spiropyrans: a quantum chemical study.

Post-synthetic modification of MOFs allows tuning the properties according to desired applications. The incorporation of photoactive molecules introduces sensitivity to radiation properties to the matrix of MOFs. We report on the theoretical analysis of possible ways of construction photoactive MOFs from UiO-67 and spiropyran molecules containing different carbonyl substituents. Large-scale computer modeling with the use of density functional theory method allowed us to select the most energy-efficient schemes of design. It was revealed that the most preferred way of immobilization of UiO-67 is the interaction with the carboxylic group in the indoline fragment of spiropyran. These results are promising for the application of MOFs modified in this way as photoactive sensors. Graphical abstract.

Synthesis of ZnO Nanoparticles Doped with Cobalt Using Bimetallic ZIFs as Sacrificial Agents.

: We report here a simple two-stage synthesis of zinc-cobalt oxide nanoparticles. We used Zn/Co-zeolite imidazolate framework (ZIF)-8 materials as precursors for annealing and optional impregnation with a silicon source for the formation of a protective layer on the surface of oxide nanoparticles. Using bimetallic ZIFs allowed us to trace the phase transition of the obtained oxide nanoparticles from wurtzite ZnO to spinel Co3O4 structures. Using (X-Ray diffraction) XRD and (X-ray Absorption Near Edge Structure) XANES techniques, we confirmed the incorporation of cobalt ions into the ZnO structure up to 5 mol.% of Co. Simple annealing of Zn/Co-ZIF-8 materials in the air led to the formation of oxide nanoparticles of about 20-30 nm, while additional treatment of ZIFs with silicon source resulted in nanoparticles of about 5-10 nm covered with protective silica layer. We revealed the incorporation of oxygen vacancies in the obtained ZnO nanoparticles using FTIR analysis. All obtained samples were comprehensively characterized, including analysis with a synchrotron radiation source.