Synthesis of struvite-enriched slow-release fertilizer using magnesium-modified biochar: Desorption and leaching mechanisms.

To improve the retention and slow-release abilities of nitrogen (N) and phosphorus (P), an 82 %-purity struvite fertilizer (MAP-BC) was synthesized using magnesium-modified biochar and a solution with a 2:1 concentration ratio of NH4+ to PO43- at a pH of 8. Batch microscopic characterizations and soil column leaching experiments were conducted to study the retention and slow-release mechanisms and desorption kinetics of MAP-BC. The slow-release mechanism revealed that the dissolution rate of high-purity struvite was the dominant factor of NP slow release. The re-adsorption of NH4+ and PO43- by biochar and unconsumed MgO prolonged slow release. Mg2+ ionized by MgO could react with PO43- released from struvite to form Mg3(PO4)2. The internal biochar exhibited electrostatic attraction and pore restriction towards NH4+, while magnesium modification and nutrient loading formed a physical antioxidant barrier that ensured long-term release. The water diffusion experiment showed a higher cumulative release rate for PO43- compared to NH4+, whereas in soil column leaching, the trend was reversed, suggesting that soil's competitive adsorption facilitated the desorption of NH4+ from MAP-BC. During soil leaching, cumulative release rates of NH4+ and PO43- from chemical fertilizers were 3.55-3.62 times faster than those from MAP-BC. The dynamic test data for NH4+ and PO43- in MAP-BC fitted the Ritger-Peppas model best, predicting release periods of 163 days and 166 days, respectively. The leaching performances showed that MAP-BC reduced leaching solution volume by 5.58 % and significantly increased soil large aggregates content larger than 0.25 mm by 24.25 %. The soil nutrients retention and pH regulation by MAP-BC reduced leaching concentrations of NP. Furthermore, MAP-BC significantly enhanced plant growth, and it is more suitable as a NP source for long-term crops. Therefore, MAP-BC is expected to function as a long-term and slow-release fertilizer with the potential to minimize NP nutrient loss and replace part of quick-acting fertilizer.

[Biological characteristics and osteogenic differentiation of magnesium-doped nanoporous titanium coating].

PURPOSE: Bioactive magnesium ions were successfully incorporated into the nanoporous titanium base coating by micro-arc oxidation(MAO), and its physical properties and osteogenic effects were explored. METHODS: Non-magnesium-containing and magnesium-containing titanium porous titanium coatings(MAO, MAO-mg) were prepared by changing the composition of MAO electrolyte and controlling the doping of magnesium in porous titanium coatings. The samples were characterized by scanning electron microscope (SEM), roughness, contact angle and energy dispersive X-ray spectrometer (EDS). Mg2+ release ability of magnesium-doped nanoporous titanium coatings was determined by inductively coupled plasma/optical emission spectrometer(ICP-OES). The structure of the cytoskeleton was determined by live/dead double staining, CCK-8 detection of material proliferation-toxicity, and staining of ß-actin using FITC-phalloidin. The effects of the coating on osteogenic differentiation in vitro were determined by alizarin red (ARS), alkaline phosphatase (ALP) staining and real-time polymerase chain reaction (qRT-PCR). SPSS 25.0 software package was used for statistical analysis. RESULTS: The MAO electrolyte with magnesium ions did not change the surface characteristics of the porous titanium coating. Each group prepared by MAO had similar microporous structure(P＞0.05). There was no significant difference in surface roughness and contact angle between MAO treatment group (MAO, MAO-mg)(P＞0.05), but significantly higher than that of Ti group (P＜0.05). With the passage of cell culture time, MAO-mg group promoted cell proliferation (P＜0.05). MAO-mg group was significantly higher than other groups in ALP and ARS staining. The expression of Runx2 mRNA (P＜0.05), ALP(P＜0.05) and osteocalcin OCN(P＜0.05) in MAO-mg group was significantly higher than that in Ti and MAO groups. CONCLUSIONS: MAO successfully prepared magnesium-containing nanoporous titanium coating, and showed a significant role in promoting osteogenic differentiation.

New Insights into the Dependence of CPEB3 Ribozyme Cleavage on Mn2+ and Mg2.

CPEB3 ribozyme is a self-cleaving RNA that occurs naturally in mammals and requires divalent metal ions for efficient activity. Ribozymes exhibit preferences for specific metal ions, but the exact differences in the catalytic mechanisms of various metal ions on the CPEB3 ribozyme remain unclear. Our findings reveal that Mn2+ functions as a more effective cofactor for CPEB3 ribozyme catalysis compared to Mg2+, as confirmed by its stronger binding affinity to CPEB3 by EPR. Cleavage assays of CPEB3 mutants and molecular docking analyses further showed that excessive Mn2+ ions can bind to a second binding site near the catalytic site, hindering CPEB3 catalytic efficiency and contributing to the Mn2+ bell-shaped curve. These results implicate a pivotal role for the local nucleobase-Mn2+ interactions in facilitating RNA folding and modulating the directed attack of nucleophilic reagents. Our study provides new insights and experimental evidence for exploring the divalent cation dependent cleavage mechanism of the CPEB3 ribozyme.

Enhancing Bone Implants: Magnesium-Doped Hydroxyapatite for Stronger, Bioactive, and Biocompatible Applications.

Hydroxyapatite (HAp) with the chemical formula Ca10(PO4)6(OH)2 is an inorganic material that exhibits morphology and composition similar to those of human bone tissues, making it highly desirable for bone regeneration applications. As one of the most biocompatible materials currently in use, HAp has undergone numerous attempts to enhance its mechanical strength. This research focuses on investigating the influence of magnesium (Mg) incorporation on the structural and mechanical properties of synthesized magnesium-doped hydroxyapatite (MgHAp) samples. Apart from its biocompatibility, Mg possesses a density and elasticity comparable to those of human bone. Therefore, incorporating Mg into HAp can be pivotal for improving bone formation. Previous studies have not extensively explored the structural changes induced by Mg substitution in HAp, which motivated us to revisit this issue. Hydrothermal synthesis technique was used to synthesize MgHAp samples with varying molar concentrations (x = 0, 0.5, 1.0, and 1.5). Theoretical simulation of HAp and MgHAp for obtaining 3D structures has been done, and theoretical X-ray diffraction (XRD) data have been compared with the experimental XRD data. Rietveld analysis revealed the alteration and deviation of lattice parameters with an increase in the Mg content, which ultimately affect the structure as well the mechanical properties of prepared samples. The findings revealed an increase in compressive stress and fracture toughness as the Mg concentration in the composition increased. Furthermore, using a finite-element analysis technique and modeling of the mechanical testing data, the von Mises stress distribution and Young's modulus values were calculated, demonstrating the similarity of the prepared samples to human cortical bone. Biocompatibility assessments using NIH-3T3 fibroblast cells confirmed the biocompatible and bioactive nature of the synthesized samples. MgHAp exhibits great potential for biomedical applications in the dental, orthopedic, and tissue engineering research fields.

In vitro demetalation of central magnesium in various chlorophyll derivatives using Mg-dechelatase homolog from the chloroflexi Anaerolineae.

In the metabolic pathway of chlorophylls (Chls), an enzyme called STAY-GREEN or SGR catalyzes the removal of the central magnesium ion of Chls and their derivatives to their corresponding free bases, including pheophytins. The substrate specificity of SGR has been investigated through in vitro reactions using Chl-related molecules. However, information about the biochemical properties and reaction mechanisms of SGR and its substrate specificity remains elusive. In this study, we synthesized various Chl derivatives and investigated their in vitro dechelations using an SGR enzyme. Chl-a derivatives with the C3-vinyl group on the A-ring, which is commonly found as a substituent in natural substrates, and their analogs with ethyl, hydroxymethyl, formyl, and styryl groups at the C3-position were prepared as substrates. In vitro dechelatase reactions of these substrates were performed using an SGR enzyme derived from an Anaerolineae bacterium, allowing us to investigate their specificity. Reactivity was reduced for substrates with an electron-withdrawing formyl or sterically demanding styryl group at the C3-position. Furthermore, the Chl derivative with the C8-styryl group on the B-ring was less reactive for SGR dechelation than the C3-styryl substrate. These results indicate that the SGR enzyme recognizes substituents on the B-ring of substrates more than those on the A-ring.

A Cu(â ¡)-eluting coating through silk fibroin film on ZE21B alloy designed for in situ endotheliazation biofunction.

In the cardiovascular field, coating containing copper used to catalyze NO (nitric oxide) production on non-degradable metal surfaces have shown unparalleled expected performance, but there are few studies on biodegradable metal surfaces. Magnesium-based biodegradable metals have been applied in cardiovascular field in large-scale because of their excellent properties. In this study, the coating of copper loaded in silk fibroin is fabricated on biodegradable ZE21B alloy. Importantly, the different content of copper is set to investigate the effects of on the degradation performance and cell behavior of magnesium alloy. Through electrochemical and immersion experiments, it is found that high content of copper will accelerate the corrosion of magnesium alloy. The reason is the spontaneous micro-batteries between copper and magnesium with the different standard electrode potentials, that is, the galvanic corrosion accelerates the corrosion of magnesium alloy. Moreover, the coating formed through silk fibroin by the right amount copper not only have a protective effect on the ZE21B alloy substrate, but also promotes the adhesion and proliferation of endothelial cells in blood vessel micro-environment. The production of NO catalyzed by copper ions makes this trend more significant, and inhibits the excessive proliferation of smooth muscle cells. These findings can provide guidance for the amount of copper in the coating on the surface of biodegradable magnesium alloy used for cardiovascular stent purpose.

Geometric deep learning for the prediction of magnesium-binding sites in RNA structures.

Magnesium ions (Mg2+) are essential for the folding, functional expression, and structural stability of RNA molecules. However, predicting Mg2+-binding sites in RNA molecules based solely on RNA structures is still challenging. The molecular surface, characterized by a continuous shape with geometric and chemical properties, is important for RNA modelling and carries essential information for understanding the interactions between RNAs and Mg2+ ions. Here, we propose an approach named RNA-magnesium ion surface interaction fingerprinting (RMSIF), a geometric deep learning-based conceptual framework to predict magnesium ion binding sites in RNA structures. To evaluate the performance of RMSIF, we systematically enumerated decoy Mg2+ ions across a full-space grid within the range of 2 to 10 Å from the RNA molecule and made predictions accordingly. Visualization techniques were used to validate the prediction results and calculate success rates. Comparative assessments against state-of-the-art methods like MetalionRNA, MgNet, and Metal3DRNA revealed that RMSIF achieved superior success rates and accuracy in predicting Mg2+-binding sites. Additionally, in terms of the spatial distribution of Mg2+ ions within the RNA structures, a majority were situated in the deep grooves, while a minority occupied the shallow grooves. Collectively, the conceptual framework developed in this study holds promise for advancing insights into drug design, RNA co-transcriptional folding, and structure prediction.

Magnesium calcites for CO2 capture and thermochemical energy storage using the calcium-looping process.

In this study, a precipitation-based synthesis method has been employed to prepare magnesium calcites with the general formula Ca1-xMgxCO3, with the objective of use them in the calcium looping (CaL) process for CO2 capture (CaL-CCS) and thermochemical energy storage (CaL-CSP). The structure and microstructure of the samples have been characterized. It has been found by X-ray diffraction that the samples with a Ca:Mg molar ratio of 0.5:0.5 and 0.55:0.45 are phase pure, while the samples with molar ratios of 0.7:0.3 and 0.8:0.2 are composed by two phases with different stoichiometry. In addition, the sample prepared with calcium alone shows the aragonite phase. The microstructure of the magnesium-containing samples is composed of nanocrystals, which are aggregated in spherical particles whereas the aragonite sample presents a typical rod-like morphology. The multicycle tests carried out under CaL-CCS conditions show that an increase on the MgO content in the calcined samples results in a reduced value of effective conversion when compared to aragonite. On the other hand, under CaL-CSP conditions, the samples with the higher MgO content exhibit nearly stable effective conversion values around 0.5 after 20 cycles, which improve the results obtained for aragonite and those reported for natural dolomite tested under the same conditions.

Ce-doped MgO films on AZ31 alloy substrate for biomedical applications: preparation, characterization and testing.

Magnesium ions, MgO nanoparticles and thin films, magnesium alloys and cerium compounds are materials intensively studied due to their corrosion protection, antibacterial and pharmacological properties. In this work, we have designed, prepared and investigated, novel thin films of MgO doped with cerium, deposited on Mg alloy (AZ31) for temporary implants, in order to enhance their life time. More precisely, we report on microstructure and corrosion behavior of MgO pure and doped with 0.1 at % Ce films, fabricated by sol-gel route coupled with spin-coating technique, on AZ31 alloy substrate. A modified sol-gel method that start from magnesium acetylacetonate, cerium nitrate and 2-methoxyethanol (as a stabilizer for the sol) was been used successfully for cerium doped MgO sol precursor preparation. The structure and morphology of the surface of the coatings, before and after immersion for 7-30 d in Hank's solution at 37 °C, were characterized by x-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscope, x-ray photoelectron spectroscopy and Fourier infrared transmittance spectrum (FT-IR). A comparison between the corrosion protection of undoped MgO and MgO doped with 0.1 at % Ce coatings on the AZ31 alloy substrate is performed by electrochemical tests and immersion tests using open circuit potential and electrochemical impedance spectroscopy in Hank's solution, at 37 °C. The electrochemical results showed that the protection of the AZ31 alloy substrate against corrosion was better with the doped with 0.1 at % Ce MgO film deposited than with pure MgO coting. The investigations of the films after immersion in Hank's solution, at 37 °C, for 7, 21 and 30 d indicated that the grown layer on the film is bone like apatite that suggests a good bioactivity of 0.1 at % Ce-doped MgO coating. Our work demonstrates that the performance corrosion protection of the biodegradable magnesium alloys used for orthopedic applications, in simulated physiological environments (Hank and Ringer) can be enhanced through coating with Ce3+doped MgO sol-gel thin film.

In vitroanalysis of insoluble salt formation mechanism associated with Mg corrosion-variations depending on the diffusion environment in model tissue.

Magnesium (Mg) alloys have attracted attention as biodegradable metals, but the details of their corrosion behavior under biological environment have not been elucidated. Previous studies have suggested that diffusion through blood flow may influence Mg corrosion. Therefore, to understand the degradation behaviors of Mg, we analyzed insoluble salt precipitation associated with Mg corrosion in model tissue with different diffusion rates. A pure Mg specimen was immersed into a model tissue prepared with cell culture medium supplemented by a thickener at a different concentration (0.2%-0.5%) to form the gel. Micro-focus x-ray computed tomography of the gel was performed to observe gas cavity formation around the specimen. The insoluble salt layer formed on the specimen surface were analyzed by scanning electron microscopy with energy-dispersive x-ray spectroscopy, and Raman spectroscopy. As results, gas cavity formation was observed for all specimens. At day 7, the gas cavity volume was the highest at 0.5% thickener gel followed by 0.3% thickener gel. The insoluble salts were classified into three types based on their morphology; plate-like, granular-like, and crater-like salts. The crater-like salts were observed to cover 16.8 ± 3.9% of the specimen surface immersed in the 0.5% thickener gel, at the specimen area contacted to the gas cavity. The crater-like salts were composed by Mg hydroxide and carbonate from the deepest to the top layer. In plate-like or granular-like salts, Mg carbonate was formed in the deepest layer, but phosphates and carbonates, mainly containing calcium not Mg, were formed on the surface layer. In conclusion, the increase in the thickener concentration increased the gas cavity volume contacting to the specimen surface, resulting in the increase in precipitation of Mg hydroxide and carbonate, composing crater-like salts. Mg hydroxide and carbonate precipitation suggests the local increase in OH-concentration, which may be attributed to the decrease in diffusion rate.

Synthesis and investigation of novel boron- and magnesium-doped YAG:Ce and LuAG:Ce phosphor ceramics.

YAG:Ce and LuAG:Ce ceramics are widely used as scintillator materials that convert high-energy radiation into visible light. For the practical application of such compounds, short decay times are a necessity. One way of shortening the existing decay times even more is to change the local environment of emitting ions by means of doping the matrix with additional elements, for example, boron or magnesium. Furthermore, boron ions also can help absorb gamma rays more efficiently, therefore improving overall applicability. Due to the aforementioned reasons, YAG and LuAG ceramics doped with cerium, boron, and magnesium were synthesized. Initial amorphous powders have been obtained by means of sol-gel synthesis and pressed into pellets under isostatic pressure and finally calcinated to form crystalline ceramics. The effects of boron and magnesium doping on the morphological, structural, and luminescence properties were investigated. The key results showed that doping with boron has indeed shortened the decay times of the garnet pellets. Overall, boron doping of ceramics is a relatively new research area; however, it is rather promising as it helps both to improve the luminescence properties and to increase particle growth rate.

Tuning biodegradability, bone-bonding capacity, and wear resistance of zinc-30% magnesium intermetallic alloy for use in load-bearing bone applications.

This work aimed to improve the rapid biodegradation, poor wear resistance properties, and lack of bioactivity of metallic biomaterials to be used in orthopedic applications. In this context, zinc-magnesium (Zn-Mg) alloy with successive contents of calcium silicate (CaSiO3) and silicon nitride (Si3N4) was prepared using powder metallurgy technique. After sintering, their phase composition and microstructure were investigated using the X-ray diffraction technique and scanning electron microscopy (SEM), respectively. Furthermore, their degradation behavior and ability to form hydroxyapatite (HA) layer on the sample surface after immersion in simulated body fluid (SBF) were monitored using weight loss measurements, inductively coupled plasma-atomic emission spectroscopy, and SEM. Moreover, their tribo-mechanical properties were measured. The results obtained showed that the successive contents of CaSiO3 were responsible for improving the bioactivity behavior as indicated by a good formation of the HA layer on the samples' surface. Additionally, ceramic materials were responsible for a continuous decrease in the released ions in the SBF solution as indicated by the ICP results. The tribology properties were significantly improved even after exposure to different loads. Based on the above results, the prepared nanocomposites are promising for use in orthopedic applications.

Raspberry-like PLA/PGS biodegradable microparticles with urethane linkages: Unlocking tailored release of magnesium ions and oxygen for bone tissue engineering.

Designing biodegradable microparticles with finely controlled release properties for tissue engineering systems remains a significant scientific challenge. This study introduces a novel approach by fabricating urethane-linked PLA/PGS microparticles loaded with magnesium peroxide. The microparticles offer potential applications in bone tissue engineering due to their ability to provide a controlled release of oxygen and magnesium ions while maintaining physiological pH. The PGS pre-polymer was synthesized via polycondensation and characterized using FTIR, 1H NMR, and GPC. Microparticle morphology transformed from smooth to raspberry-like upon incorporation of PGS, as observed by SEM. Microparticle size was tuned by varying PGS and PLA concentrations. FTIR analysis confirmed the successful formation of urethane links within the microparticles. MgO2-loaded PLA/PGS microparticles exhibited sustained release of dissolved oxygen and magnesium ions for 21 days while maintaining physiological pH better than PLA microparticles. Cell viability assays confirmed microparticle cytocompatibility, and ALP and Alizarin red assays demonstrated their ability to induce osteogenic differentiation. These findings highlight the potential of pH-controlled MgO2-loaded microparticles as an effective system for bone tissue engineering. In conclusion, this study presents a novel approach to designing biodegradable microparticles with adjustable release properties for bone tissue engineering. The urethane-based MgO2-loaded microparticles provide controlled release of oxygen and magnesium ions and regulate the environment's pH, making them a promising system for bone tissue engineering applications.

The reversible activation of norovirus by metal ions.

Murine norovirus (MNV) undergoes extremely large conformational changes in response to the environment. The T = 3 icosahedral capsid is composed of 180 copies of ~58-kDa VP1 comprised of N-terminus (N), shell (S), and C-terminal protruding (P) domains. At neutral pH, the P domains are loosely tethered to the shell and float ~15 Å above the surface. At low pH or in the presence of bile salts, the P domain drops onto the shell and this movement is accompanied by conformational changes within the P domain that enhance receptor interactions while blocking antibody binding. While previous crystallographic studies identified metal binding sites in the isolated P domain, the ~2.7-Å cryo-electron microscopy structures of MNV in the presence of Mg2+ or Ca2+ presented here show that metal ions can recapitulate the contraction observed at low pH or in the presence of bile. Further, we show that these conformational changes are reversed by dialysis against EDTA. As observed in the P domain crystal structures, metal ions bind to and contract the G'H' loop. This movement is correlated with the lifting of the C'D' loop and rotation of the P domain dimers about each other, exposing the bile salt binding pocket. Isothermal titration calorimetry experiments presented here demonstrate that the activation signals (bile salts, low pH, and metal ions) act in a synergistic manner that, individually, all result in the same activated structure. We present a model whereby these reversible conformational changes represent a uniquely dynamic and tissue-specific structural adaptation to the in vivo environment.IMPORTANCEThe highly mobile protruding domains on the calicivirus capsids are recognized by cell receptor(s) and antibodies. At neutral pH, they float ~15 Å above the shell but at low pH or in the presence of bile salts, they contract onto the surface. Concomitantly, changes within the P domain block antibody binding while enhancing receptor binding. While we previously demonstrated that metals also block antibody binding, it was unknown whether they might also cause similar conformational changes in the virion. Here, we present the near atomic cryo-electron microscopy structures of infectious murine norovirus (MNV) in the presence of calcium or magnesium ions. The metal ions reversibly induce the same P domain contraction as low pH and bile salts and act in a synergistic manner with the other stimuli. We propose that, unlike most other viruses, MNV facilely changes conformations as a unique means to escape immune surveillance as it moves through various tissues.

Optimization of enzymatic saccharification of industrial wastes using a thermostable and halotolerant endoglucanase through Box-Behnken experimental design.

This study describes the production, characterization and application of an endoglucanase from Penicillium roqueforti using lignocellulosic agro-industrial wastes as the substrate during solid-state fermentation. The endoglucanase was generated after culturing with different agro-industrial wastes for 96 h without any pretreatment. The highest activity was obtained at 50 °C and pH 4.0. Additionally, the enzyme showed stability in the temperature and pH ranges of 40-80 °C and 4.0-5.0, respectively. The addition of Ca2+, Zn2+, Mg2+, and Cu2+ increased enzymatic activity. Halotolerance as a characteristic of the enzyme was confirmed when its activity increased by 35% on addition of 2 M NaCl. The endoglucanase saccharified sugarcane bagasse, coconut shell, wheat bran, cocoa fruit shell, and cocoa seed husk. The Box-Behnken design was employed to optimize fermentable sugar production by evaluating the following parameters: time, substrate, and enzyme concentration. Under ideal conditions, 253.19 mg/g of fermentable sugars were obtained following the saccharification of wheat bran, which is 41.5 times higher than that obtained without optimizing. This study presents a thermostable, halotolerant endoglucanase that is resistant to metal ions and organic solvents with the potential to be applied in producing fermentable sugars for manufacturing biofuels from agro-industrial wastes.

Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L-lactic-co-glycolic acid-based substrate for cardiovascular device application.

Biodegradable drug-eluting stents (DESs) are gaining importance owing to their attractive features, such as complete drug release to the target site. Magnesium (Mg) alloys are promising materials for future biodegradable DESs. However, there are few explorations using biodegradable Mg for cardiovascular stent application. In this present study, sirolimus-loaded poly D, L-lactic-co-glycolic acid (PLGA)-coated/ sirolimus-fixed/AZ91 Mg alloy-based substrate was developed via a layer-by-layer approach for cardiovascular stent application. The AZ91 Mg alloy was prepared through the squeeze casting technique. The casted AZ91 Mg alloy (Mg) was alkali-treated to provide macroporous networks to hold the sirolimus and PLGA layers. The systematic characterization was investigated via electrochemical, optical, physicochemical, and in-vitro biological characteristics. The presence of the Mg17 Al12 phase in the Mg sample was found in the x-ray diffraction system (XRD) spectrum which influences the corrosion behavior of the developed substrate. The alkali treatment increases the substrate's hydrophilicity which was confirmed through static contact angle measurement. The anti-corrosion characteristic of casted-AZ91 Mg alloy (Mg) was slightly less than the sirolimus-loaded PLGA-coated alkali-treated AZ91 Mg alloy (Mg/Na/S/P) substrate. However, dissolution rates for both substrates were found to be controlled at cell culture conditions. Radiographic densities of AZ91 Mg alloy substrates (Mg, Mg/Na, and Mg/Na/S/P) were measured to be 0.795 ± 0.015, 0.742 ± 0.01, and 0.712 ± 0.017, respectively. The star-shaped structure of 12% sirolimus/PLGA ensures the bioavailability of the drugs. Sirolimus release kinetic was fitted up to 80% with the "Higuchi model" for Mg samples, whereas Mg/Na/S/P showed 45% fitting with a zero-order mechanism. The Mg/Na/S/P substrate showed a 70% antithrombotic effect compared to control. Further, alkali treatment enhances the antibacterial characteristic of AZ91 Mg alloy. Also, the alkali-treated sirolimus-loaded substrates (Mg/Na/S and Mg/Na/S/P) inhibit the valvular interstitial cell's growth significantly in in-vitro. Hence, the results imply that sirolimus-loaded PLGA-coated AZ91 Mg alloy-based substrate can be a potential candidate for cardiovascular stent application.

A strategy for enhancing bioactivity and osseointegration with antibacterial effect by incorporating magnesium in polylactic acid based biodegradable orthopedic implant.

Biodegradable orthopedic implants are essential for restoring the physiological structure and function of bone tissue while ensuring complete degradation after recovery. Polylactic acid (PLA), a biodegradable polymer, is considered a promising material due to its considerable mechanical properties and biocompatibility. However, further improvements are necessary to enhance the mechanical strength and bioactivity of PLA for reliable load-bearing orthopedic applications. In this study, a multifunctional PLA-based composite was fabricated by incorporating tricalcium phosphate (TCP) microspheres and magnesium (Mg) particles homogenously at a volume fraction of 40 %. This approach aims to enhance mechanical strength, accelerate pore generation, and improve biological and antibacterial performance. Mg content was incorporated into the composite at varying values of 1, 3, and 5 vol% (referred to as PLA/TCP-1 Mg, PLA/TCP-3 Mg, and PLA/TCP-5 Mg, respectively). The compressive strength and stiffness were significantly enhanced in all composites, reaching 87.7, 85.9, and 84.1 MPa, and 2.7, 3.0, and 3.1 GPa, respectively. The degradation test indicated faster elimination of the reinforcers as the Mg content increased, resulting in accelerated pore generation to induce enhanced osseointegration. Because PLA/TCP-3 Mg and PLA/TCP-5 Mg exhibited cracks in the PLA matrix due to rapid corrosion of Mg forming corrosion byproducts, to optimize the Mg particle content, PLA/TCP-1 Mg was selected for further evaluation. As determined by in vitro biological and antibacterial testing, PLA/TCP-1 Mg showed enhanced bioactivity with pre-osteoblast cells and exhibited antibacterial properties by suppressing bacterial colonization. Overall, the multifunctional PLA/TCP-Mg composite showed improved mechanobiological performance, making it a promising material for biodegradable orthopedic implants.

Enhanced simultaneous removal of phosphate and ammonium from swine wastewater using magnetic magnesium-loaded Chinese herbal medicine residues: Performance, mechanism, and resource utilization.

Magnetic magnesium (Mg)-loaded Chinese herbal medicine residues (MM-TCMRs) were fabricated to simultaneously remove and recover phosphate and ammonium from wastewater. The MM-TCMRs exhibited larger specific surfaces and rougher structures with massive spherical particles than those of original residues. They could be separated by adjusting the magnetic field. The phosphate and ammonium adsorption by MM-TCMRs were matched with the pseudo-second-order model, while the Langmuir model yielded the maximum adsorption capacities of 635.35 and 615.57 mg g-1, respectively. Struvite precipitation on the MM-TCMRs surface was the primary removal mechanism with electrostatic attraction, ligand exchange, intra-particle diffusion, and ion exchange also involved. The recyclability of MM-TCMRs confirmed their good structural stability. More importantly, the nutrient-loaded MM-TCMRs enhanced alfalfa growth and improved soil fertility in planting experiments. Collectively, the MM-TCMRs are promising candidates for nutrient removal and recovery from wastewater.

Incorporating pH/NIR responsive nanocontainers into a smart self-healing coating for a magnesium alloy with controlled drug release, bacteria killing and osteogenesis properties.

Magnesium (Mg)-based orthopedic implant materials can potentially be protected from deterioration using a protective polymer coating. However, this coating is susceptible to excessive corrosion and accidental scratches. Moreover, the inadequate bone integration and infections associated with bone implants present additional challenges that hinder their effective use. In this work, a spin-spray layer-by-layer (SSLbL) assembly technique was employed to develop a smart self-healing coating for Mg alloy WE43. This coating was based on paeonol-encapsulated nanocontainers (PMP) that were modified with a stimuli-responsive polydopamine (PDA). The leached paeonol could form a compact chelating layer when complexed with Mg2+ ions. Dynamic reversible hydrogen bonds were formed between assembly units, which ensured that the hybrid coating possessed rapid and cyclic self-healing properties. Under 808 nm near-infrared (NIR) laser irradiation, the self-healing coating exhibited antibacterial properties due to the synergistic effects of hyperthermia, reactive oxygen species (ROS), and paeonol. In addition, the incorporation of nanoparticles into the hybrid coating led to improvements in the cytocompatibility and osteogenic properties of the implant material. The smart coating enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization, and the expression of osteogenic genes. This study presents a promising opportunity to explore the application of a smart self-healing coating for a Mg alloy. STATEMENT OF SIGNIFICANCE: Herein, we report a self-healing coating comprised of polyethyleneimine and nanocontainer-crosslinked hyaluronic acid to achieve drug-controlled release, antimicrobial activity, and osteogenesis performance. The formation of hydrogen bonds between HA and PEI facilitated the self-assembly process, thereby improving the coating's corrosion resistance and adhesion strength. The hybrid coating exhibited a rapid and cyclic self-healing activity due to paeonol and dynamic reversible bonds. The release of paeonol was controlled by pH and NIR stimuli owing to polydopamine modification. In vitro testing revealed that the hybrid coating achieved effective bacteria eradication through synergistic effects of hyperthermia, reactive oxygen species, and paeonol. Moreover, the smart coating was found to enhance alkaline phosphatase activity, extracellular matrix mineralization, and the expression of osteogenic genes.

Direct Determination of Ca, K, and Mg in Soy Leaf Samples Using Laser-Induced Breakdown Spectroscopy.

This study was dedicated to developing analytical methods for determining macronutrients (Ca, K, and Mg) in soy leaf samples with and without petioles. The study's primary purpose was to present Laser-induced breakdown spectroscopy (LIBS) as a viable alternative for directly analyzing leaf samples using chemometric tools to interpret the data obtained. The instrumental condition chosen for LIBS was 70 mJ of laser pulse energy, 1.0 µs of delay time, and 100 µm of spot size, which was applied to 896 samples: 305 of soy without petioles and 591 of soy with petioles. The reference values of the analytes for the proposition of calibration models were obtained using inductively coupled plasma optical emission spectroscopy (ICP-OES) technique. Twelve normalization modes and two calibration strategies were tested to minimize signal variations and sample matrix microheterogeneity. The following were studied: multivariate calibration using partial least squares and univariate calibration using the area and height of several selected emission lines. The notable normalization mode for most models was the Euclidean norm. No analyte showed promising results for univariate calibrations. Micronutrients, P and S, were also tested, and no multivariate models presented satisfactory results. The models obtained for Ca, K, and Mg showed good results. The standard error of calibration ranged from 2.3 g/kg for Ca in soy leaves without petioles with two latent variables to 5.0 g/kg for K in soy leaves with petioles with two latent variables.