Mechanochemical recycling of cellulose multilayer carton packages to produce micro and nanocellulose from the perspective of techno-economic and environmental analysis.

Despite being composed of recyclable materials, the main technological challenge of multilayer carton packs involves the efficient decompatibilization of the cellulosic, polymeric, and metallic phases. Here, a simple two-step mechanochemical process is described that uses only aqueous media and mechanical force to promote phase separation in order to fully recycle multi-layer carton packaging. The first step produces value-added micro- and nanocellulose, while in the second step, aluminum is extracted, forming precipitated aluminum and aluminum oxyhydroxides. Solid polyethylene (PE) remains with a degree of purity defined by the process efficiency. The results show that cellulose is efficiently extracted and converted into micro- and nanocellulose after 15 min of milling. In the second stage, approximately 90% of the aluminum is extracted from the PE after 15 min of milling. Due to the separation and drying medium conditions, the finely divided particles of extracted aluminum also have oxyhydroxides in their composition. It is believed that a passivation layer forms on the metallic aluminum particle. The techno-economic analysis revealed a positive net present value (NPV) of $17.5 million, with a minimum selling price of 1.62 USD/kg of cellulose. The environmental analysis concluded that most of the environmental impact of the process is associated with the entry of carton packages into the system, incorporating a small environmental load related to the industrial process. The results indicate a promising option toward a circular economy and carbon neutrality.

Infrared spectroscopy as a predictive tool for the severity of COVID-19 using patient's saliva: A strategy to avoid hyperinflammation.

Discriminate the severity level of COVID-19 disease is still a challenge. Here we investigate the capability of micro-infrared absorption spectroscopy (micro-FTIR) to probe COVID-19 severity level and predict hyperinflammation, correlating the assigned vibrational data to relevant biomolecules related to the immune system. Saliva of 184 patients was analysed by ELISA assay (Hepcidin) and micro-FTIR. Vibrational bands related to IgM and IgA can discriminate healthy from Severe individuals (sensitivity ≥ 0.749, specificity ≥ 0.945) and are less effective in discriminating Mild or Moderate individuals from the Severe group (sensitivity ≥ 0.628, specificity ≥ 0.867). Analysis of the second derivative of spectra probed increased levels of IL-6 in the saliva a key additional information for the degree of severity prediction. Because the model discriminates all the groups regarding the Severe group, it predicts an intense state of inflammation based on FTIR analysis. It is a powerful tool for predicting hyperinflammation conditions related to SARS-CoV-2 infection and may be an ally in implementing drugs or therapeutic approaches to manage COVID-19 in the Severe stage in healthcare facilities.

Confined Water Dynamics in the Scaffolds of Polylactic Acid.

Resorbable polylactic acid (PLA) ultrathin fibers have been applied as scaffolds for tissue engineering applications due to their micro- and nanoporous structure that favor cell adhesion, besides inducing cell proliferation and upregulating gene expression related to tissue regeneration. Incorporation of multiwalled carbon nanotubes into PLA fibers has been reported to increase the mechanical properties of the scaffold, making them even more suitable for tissue engineering applications. Ideally, scaffolds should be degraded simultaneously with tissue growth. Hydration and swelling are factors related to scaffold degradation. Hydration would negatively impact the mechanical properties since PLA shows hydrolytic degradation. Water absorption critically affects the catalysis and allowance of the hydrolysis reactions. Moreover, either mass transport and chemical reactions are influenced by confined water, which is an unexplored subject for PLA micro- and nanoporous fibers. Here, we probe and investigate confined water onto highly porous PLA microfibers containing few amounts of incorporated carbon nanotubes by Fourier transform infrared (FTIR) spectroscopy. A hydrostatic pressure was applied to the fibers to enhance the intermolecular interactions between water molecules and C=O groups from polyester bonds, which were evaluated over the wavenumber between 1600 and 2000 cm-1. The analysis of temperature dependence of FTIR spectra indicated the presence of confined water which is characterized by a non-Arrhenius to Arrhenius crossover at T0 = 190 K for 1716 and 1817 cm-1 carbonyl bands of PLA. These bands are sensitive to a hydrogen bond network of confined water. The relevance of our finding relies on the challenge detecting confined water in hydrophobic cavities as in the PLA one. To the best of our knowledge, we present the first report referring the presence of confined water in a hydrophobic scaffold as PLA for tissue engineering. Our findings can provide new opportunities to understand the role of confined water in tissue engineering applications. For instance, we argue that PLA degradation may be affected the most by confined water. PLA degradation involves hydrolytic and enzymatic degradation reactions, which can both be sensitive to changes in water properties.

Revealing the Structure Formation on Polyglycerol Citrate Polymers-An Environmentally Friendly Polyester as a Seed-Coating Material.

A detailed structural investigation of a promising bio-based polymer, polyglycerol citrate polyester, obtained by the bulk polycondensation of glycerol (Gly) against citric acid (Cit) under mild reaction was performed. The reaction in conditions with and without catalyst use (sulfuric acid, H2SO4) was investigated, showing evidence that it is possible to modify the polymer solubility according to the ratio and catalyst utilization. 13C and 1H NMR indicated that synthesis catalyzed with Cit excess leads to higher esterification degrees of citrate groups. In contrast, the Gly moieties are more prominent in catalyzed polymers regardless of the excess monomers. Overall, a successful conversion of Gly and Cit into polyesters was attained even without catalysis, enabling a simple route for the large-scale production of this green material to be used as a coating material. This polymer has been shown to be well-suited for coating seeds and might be a promising material for similar agricultural applications. Tests on soybean seed coating with a PGCit solution of 75% indicated that the seed quality and germination rate were not affected by the PGCit coating, concluding that this polymer is suitable for this application.

A colloidal hydrogel-based drug delivery system overcomes the limitation of combining bisphosphonates with bioactive glasses: in vitro evidence of a potential selective bone cancer treatment allied with bone regeneration.

Bisphosphonates are a class of drugs that induce bone cancer cell death and favor bone regeneration, making them suitable for bone cancer treatment. However, when combined with bioactive glasses to enhance bone regeneration, a chemical bond between biphosphonates and the glass surface inactivates their mechanism of action. A new colloidal hydrogel-based drug delivery system could overcome that limitation once bisphosphonates, such as zoledronic acid (ZA), are incorporated into hydrogel micelles, avoiding their interaction with the glass surface. In this work, we proposed formulations based on a poloxamer 407 thermo-responsive hydrogel matrix containing holmium-doped bioactive glass nanoparticles and different concentrations (0.05 and 5 mg/mL) of ZA. We characterized the influence of the glass and the ZA on the hydrogel properties. In addition, a drug concentration screening was performed, and biological characterizations evaluated the best result. The biological characterization consisted of evaluating cytotoxicity and in vitro bone regeneration ability through cell migration and quantification of genes related to osteogeneses through RT-PCR. The results suggest that the addition of glasses and ZA to the poloxamer did not significantly influence the sol-gel transition of the hydrogels (around 13 °C) regardless of the ZA content. However, the ZA at high concentration (PL-ZA100) decreased the enthalpy of gel formation from 68 to 43 kJ.mol-1 when compared with the pure hydrogel formulation (PL), suggesting a water structurer role of ZA, which is withdrawn when glass particles are added to the system (PL-BG5Ho-ZA100). Solid-state 31P nuclear resonance spectroscopy results showed that part of the ZA is chemically bonded to the glass surface, which explains the withdrawal in the water structurer role of ZA when the glasses were incorporated into the hydrogel. Besides, based on the drug release results, we proposed a model where part of the ZA is "free," encapsulated in the hydrogel matrix, while another part of the ZA is bonded to the glass surface. Finally, considering the in vitro results and our proposed model, the ratio between "free" and "bonded" ZA in our drug delivery systems showed in vitro evidence of a cancer treatment that selectively kills osteosarcoma cells while still favoring an osteogenic microenvironment. By overcoming the limitation of combining bisphosphonates with bioactive glasses, hydrogel-based drug delivery systems can be a solution for the development of new formulations proposed for bone cancer treatment in conjunction with bone regeneration.

Bioactive Glasses as Carriers of Cancer-Targeted Drugs: Challenges and Opportunities in Bone Cancer Treatment.

The treatment of bone cancer involves tumor resection followed by bone reconstruction of the defect caused by the tumor using biomaterials. Additionally, post-surgery protocols cover chemotherapy, radiotherapy, or drug administration, which are employed as adjuvant treatments to prevent tumor recurrence. In this work, we reviewed new strategies for bone cancer treatment based on bioactive glasses as carriers of cancer-targeted and other drugs that are intended for bone regeneration in conjunction with adjuvant treatments. Drugs used in combination with bioactive glasses can be classified into cancer-target, osteoclast-target, and new therapies (such as gene delivery and bioinorganic). Microparticulated, nanoparticulated, or mesoporous bioactive glasses have been used as drug-delivery systems. Additionally, surface modification through functionalization or the production of composites based on polymers and hydrogels has been employed to improve drug-release kinetics. Overall, although different drugs and drug delivery systems have been developed, there is still room for new studies involving kinase inhibitors or antibody-conjugated drugs, as these drugs have been poorly explored in combination with bioactive glasses.

A 58S bioactive glass for dentin hypersensitivity and erosive tooth wear: An in vitro study.

OBJECTIVES: To assess the effect of an experimental 58S bioactive glass on dentin permeability (dP) and erosive tooth wear (dentin surface loss - dSL). METHODS: 58S bioactive glass was synthetized using a sol-gel methodology, following by lyophilization and calcination, then mixed with phosphoric acid to obtain a paste (BGP). Forty-eight dentin disks (1 mm-thick) were used for dP, and 48 dentin slabs (3 mm × 3 mm) for dSL, which were assessed at three time intervals: post-EDTA (5 min in 17% EDTA solution); post-treatment (C: distilled water; BGP: experimental bioactive glass paste; NP: Nupro prophylaxis paste; CXT: Clinpro XT varnish); and post-erosive/abrasive cycling. Data were statistically analyzed (α=0.05). RESULTS: For dP and dSL, Groups did not differ significantly post-EDTA (p>0.05). Post-treatment, all groups showed lower dP than C (p<0.05), without differing significantly among them. For the dSL analysis, Groups C, BGP and NP did not differ significantly, showing lower values than CXT (p<0.05). Post-cycling, C continued to show the highest dP (p<0.05). Specimens from Group CXT had the lowest dP and did not differ from NP (p=0.86) which did not differ from BGP (p=0.193). For C and BGP, dP value was higher post-cycling than post-treatment (p<0.05). For NP and CXT, these experimental times did not differ (p>0.05). Post-cycling, dSL for C, BGP and NP did not differ significantly; values were higher than those for CXT (p<0.05). CONCLUSIONS: BGP reduced dP after application, with a reduced effect after cycling. Nonetheless, it was not able to protect dentin against erosive tooth wear. CLINICAL SIGNIFICANCE: Minimizing dentin hypersensitivity is a challenge in the field of dentistry. The development of alternative products with potential to obliterate dentinal tubules and provide resistance to chemical/mechanical stimuli is, thus, highly desirable. We have proposed a material able to reduce dentin permeability, which has emerged as a promising alternative for this purpose.

Superparamagnetic and highly bioactive SPIONS/bioactive glass nanocomposite and its potential application in magnetic hyperthermia.

Magnetic bioactive glass-ceramics are biomaterials applied for magnetic hyperthermia in bone cancer treatment, thereby treating the bone tumor besides regenerating the damaged bone. However, combining high bioactivity and high saturation magnetization remains a challenge since the thermal treatment step employed to grow magnetic phases is also related to loss of bioactivity. Here, we propose a new nanocomposite made of superparamagnetic iron oxide nanoparticles (SPIONs) dispersed in a sol-gel-derived bioactive glass matrix, which does not need any thermal treatment for crystallization of magnetic phases. The scanning and transmission electron microscopies, X-ray diffraction, and dynamic light scattering results confirm that the SPIONs are actually embedded in a nanosized glass matrix, thus forming a nanocomposite. Magnetic and calorimetric characterizations evidence their proper behavior for hyperthermia applications, besides evidencing inter-magnetic nanoparticle interactions within the nanocomposite. Bioactivity and in vitro characterizations show that such nanocomposites exhibit apatite-forming properties similar to the highly bioactive parent glass, besides being osteoinductive. This methodology is a new alternative to produce magnetic bioactive materials to which the magnetic properties only rely on the quality of the SPIONs used in the synthesis. Thereby, these nanocomposites can be recognized as a new class of bioactive materials for applications in bone cancer treatment by hyperthermia.

Asbestos cement waste treatment through mechanochemical process with KH2PO4 for its utilization in soil pH correction and nutrient delivery.

The manufacture of asbestos materials has been banished worldwide due to their toxicity, but discarding the existing wastes remains a challenge. We investigated an alternative mechanochemical method to treat asbestos-cement materials by loading them with potassium and phosphorus from KH2PO4 during the milling process to obtain a product used as liming and soil conditioner. The results showed total asbestos fibrous elimination after 7 to 8 h of milling. The materials showed a slow-release fertilizer profile. The liming property is maintained when the asbestos-cement weight proportion used is equal to or higher than KH2PO4. A comparative soil experiment with limestone also indicates that lower doses of the K- and P-enriched detoxified asbestos cement were required to reach similar liming effects. Maize cultivation (greenhouse) was used to evaluate its performance showing higher biomass production for the sample loaded with potassium and phosphorous.

Bonding Reactions of Dental Self-Adhesive Cements with Synthetic Hydroxyapatite as a Function of the Polymerization Protocol.

OBJECTIVES: This study evaluated the influence of the cement composition and different polymerization protocols on the bonding chemical interaction of self-adhesive cements with synthetic hydroxyapatite. MATERIALS AND METHODS: Two commercial self-adhesive resin cements (RelyX U200 and Maxcem Elite) were selected, manipulated, mixed with hydroxyapatite dry powder (HAp), dispensed into molds, and distributed into three groups according to polymerization protocols: immediate photoactivation (IP); delayed photoactivation, 10 min self-curing and light-curing (DP); and chemical activation (CA, no light exposure). The detailed chemical information, at atomic scale, on the surface and deeper into the bulk of self-adhesive cement/hydroxyapatite mixtures was evaluated with X-ray photoelectron spectroscopy (XPS). RESULTS: Chemical elements were detected in both cements, such as Na, O, Ca, C, P, and Si. Other elements were detected in minor concentrations. RelyX U200 exhibited the most intense formation of calcium salts products when the cement/HAp mixtures were photoactivated (immediate or delayed). RelyX U200/HAp mixture under delayed photoactivation (DP) also exhibited higher binding energy between calcium moieties of the HAp and methacrylates in the cement. A higher energy difference in the interaction of HAp with the cement comparing the bulk and surface areas was observed when RelyX U200 underwent the delayed photoactivation protocol. Maxcem Elite exhibited an increased chemical reactivity when either chemically activated or immediately photoactivated and a higher binding energy of the carboxyl groups bonded to the calcium of HAp when chemically activated. CONCLUSIONS: The interaction of cements with hydroxyapatite is chemical in nature and leads to the formation of calcium salts, which may favor better integrity and longevity of adhesive restorations. The polymerization protocol affects the chemical interaction in mixtures of self-adhesive cements and hydroxyapatite, influencing the formation of these salts and the establishment of intermolecular interactions between the HAp and the cements.

Bioactive glass/poloxamer 407 hydrogel composite as a drug delivery system: The interplay between glass dissolution and drug release kinetics.

Since patients suffer pain in the post-surgery of bone repair interventions, bioactive glass/hydrogel drug delivery systems containing local anesthetics, such as ropivacaine, could improve patient life quality by combining bone regeneration with anesthetics. However, poloxamer-based hydrogel properties are sensitive to ions, temperature, and water contents and could be structurally influenced by the ionic dissolution products from bioactive glasses of different compositions. Therefore, this study evaluated the interplay between bioactive glass dissolution kinetics and poloxamer 407 properties, establishing a correlation between changes in the hydrogel and drug release kinetics. Three glass compositions were produced, yielding Ca-rich, Na-rich, and an intermediate glass composition. The influence of Ca/Na ratios on the glass structure and dissolution was investigated. Further, the glasses and ropivacaine were incorporated in the poloxamer hydrogel, and the self-assembly ability of poloxamer, the degradation rate, and the drug release kinetics of the composites were evaluated. The results suggested that glass connectivity affected the early-stage of glass dissolution, while sodium mobility influenced the long-term. The dissolution products from the glasses interact with the supramolecular structure of the poloxamer, causing structural changes responsible for hydrogel degradation. Consequently, by changing the Ca/Na ratio in the glasses, it is possible to modulate glass dissolution that, in turn, influences the ropivacaine release. Thus, we propose that the Ca/Na ratio in quaternary bioactive glasses can be used to modulate drug-delivery properties from systems based on bioactive glasses and poloxamer 407.

Holmium-Containing Bioactive Glasses Dispersed in Poloxamer 407 Hydrogel as a Theragenerative Composite for Bone Cancer Treatment.

Holmium-containing bioactive glasses can be applied in bone cancer treatment because the holmium content can be neutron activated, having suitable properties for brachytherapy applications, while the bioactive glass matrix can regenerate the bone alterations induced by the tumor. To facilitate the application of these glasses in clinical practice, we proposed a composite based on Poloxamer 407 thermoresponsive hydrogel, with suitable properties for applications as injectable systems. Therefore, in this work, we evaluated the influence of holmium-containing glass particles on the properties of Poloxamer 407 hydrogel (20 w/w.%), including self-assembly ability and biological properties. 58S bioactive glasses (58SiO2-33CaO-9P2O5) containing different Ho2O3 amounts (1.25, 2.5, 3.75, and 5 wt.%) were incorporated into the hydrogel. The formulations were characterized by scanning electron microscopy, differential scanning calorimetry, rheological tests, and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] MTT cell viability against pre-osteoblastic and osteosarcoma cells. The results evidenced that neither the glass particles dispersed in the hydrogel nor the holmium content in the glasses significantly influenced the hydrogel self-assembly ability (Tmic ~13.8 °C and Tgel ~20 °C). Although, the glass particles considerably diminished the hydrogel viscosity in one order of magnitude at body temperature (37 °C). The cytotoxicity results evidenced that the formulations selectively favored pre-osteoblastic cell proliferation and osteosarcoma cell death. In conclusion, the formulation containing glass with the highest fraction of holmium content (5 wt.%) had the best biological results outcomes aiming its application as theragenerative materials for bone cancer treatment.

Strategies for Cancer Treatment Based on Photonic Nanomedicine.

Traditional cancer treatments, such as surgery, radiotherapy, and chemotherapy, are still the most effective clinical practice options. However, these treatments may display moderate to severe side effects caused by their low temporal or spatial resolution. In this sense, photonic nanomedicine therapies have been arising as an alternative to traditional cancer treatments since they display more control of temporal and spatial resolution, thereby yielding fewer side effects. In this work, we reviewed the challenge of current cancer treatments, using the PubMed and Web of Science database, focusing on the advances of three prominent therapies approached by photonic nanomedicine: (i) photothermal therapy; (ii) photodynamic therapy; (iii) photoresponsive drug delivery systems. These photonic nanomedicines act on the cancer cells through different mechanisms, such as hyperthermic effect and delivery of chemotherapeutics and species that cause oxidative stress. Furthermore, we covered the recent advances in materials science applied in photonic nanomedicine, highlighting the main classes of materials used in each therapy, their applications in the context of cancer treatment, as well as their advantages, limitations, and future perspectives. Finally, although some photonic nanomedicines are undergoing clinical trials, their effectiveness in cancer treatment have already been highlighted by pre-clinical studies.

Biomedical Radioactive Glasses for Brachytherapy.

The fight against cancer is an old challenge for mankind. Apart from surgery and chemotherapy, which are the most common treatments, use of radiation represents a promising, less invasive strategy that can be performed both from the outside or inside the body. The latter approach, also known as brachytherapy, relies on the use of implantable beta-emitting seeds or microspheres for killing cancer cells. A set of radioactive glasses have been developed for this purpose but their clinical use is still mainly limited to liver cancer. This review paper provides a picture of the biomedical glasses developed and experimented for brachytherapy so far, focusing the discussion on the production methods and current limitations of the available options to their diffusion in clinical practice. Highly-durable neutron-activatable glasses in the yttria-alumina-silica oxide system are typically preferred in order to avoid the potentially-dangerous release of radioisotopes, while the compositional design of degradable glass systems suitable for use in radiotherapy still remains a challenge and would deserve further investigation in the near future.

New sol-gel-derived magnetic bioactive glass-ceramics containing superparamagnetic hematite nanocrystals for hyperthermia application.

Although the three main phases of iron oxide - hematite, maghemite, and magnetite - exhibit superparamagnetic properties at the nanoscale, only maghemite and magnetite phases have been explored in magnetic bioactive glass-ceramics aimed at applications in cancer treatment by hyperthermia. In this work, it is reported for the first time the superparamagnetic properties of hematite nanocrystals grown in a 58S bioactive glass matrix derived from sol-gel synthesis. The glass-ceramics are based on the (100-x)(58SiO2-33CaO-9P2O5)-xFe2O3 system (x = 10, 20 and 30 wt%). A thermal treatment leads to the growth of hematite (α-Fe2O3) nanocrystals, conferring superparamagnetic properties to the glass-ceramics, which is enough to produce heat under an external alternating magnetic field. Besides, the crystallization does not inhibit materials bioactivity, evidenced by the formation of calcium phosphate onto the glass-ceramic surface upon soaking in simulated body fluid. Moreover, their cytotoxicity is similar to other magnetic bioactive glass-ceramics reported in the literature. Finally, these results suggest that hematite nanocrystals' superparamagnetic properties may be explored in multifunctional glass-ceramics applied in bone cancer treatment by hyperthermia allied to bone regeneration.

Sol-gel-derived 58S bioactive glass containing holmium aiming brachytherapy applications: A dissolution, bioactivity, and cytotoxicity study.

Bioactive glasses containing rare earth elements have been proposed as promising candidates for applications in brachytherapy of bone cancer. However, their safety relies on a proper dissolution to avoid radioactive materials in the human body, and desirable bioactive properties to regenerate the bone defect caused by the tumor. In this work, we proposed a new series of sol-gel-derived bioactive glasses containing holmium oxide, based on the system (100-x)(58SiO2-33CaO-9P2O5)-xHo2O3 (x = 1.25, 2.5 and 5 wt%). The glasses were characterized regarding their dissolution behavior, bioactivity, and cytotoxicity with pre-osteoblastic cells. Also, in the dissolution experiments, the Arrhenius and Eyring equations were used to obtain some thermodynamic properties of glass dissolution. The results evidenced that the addition of holmium ions in the glass structure decreased the energy barrier of hydrolysis reactions, which favors glass dissolution in an early-stage. However, in the long-term, the strength of Si-O-Ho bonds may be the cause of more stable dissolution. Besides, glasses containing holmium were as bioactive as the 58S bioactive glasses, a highly bioactive composition. Cytotoxicity results showed that all glasses were not cytotoxic, and the composition containing 5 wt.% of Ho2O3 enhanced cell viability. Finally, these results suggest that these glasses are suitable materials for brachytherapy applications due to their proper dissolution behavior, high bioactivity, and high cell viability.

Bioactive glass and high-intensity lasers as a promising treatment for dentin hypersensitivity: An in vitro study.

This in vitro study aimed to analyze the physical and chemical characteristics of the hypersensitive human dentin-like surface after application of a bioactive glass (BG) paste (BG/Ac) irradiated or not with high-power lasers. Dentin specimens were treated with 17% Ethylenediamine tetraacetic acid (EDTA) solution to mimic a hypersensitive dentin and then submitted to neodymium: yttrium-aluminum-garnet (Nd:YAG) laser or CO2 laser irradiation prior and after application of BG/Ac. Characterizations were performed by using X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results suggested that application of BG/Ac by itself caused some obstructions of dentinal tubules. Nd:YAG laser irradiation reduced the opening of the dentinal tubules with no changes in the collagen structure. CO2 laser irradiation caused dentin melting and resolidification along with cracks and chemical changes in collagen fibers. However, when BG/Ac paste was irradiated with lasers, a sequence of surface reactions between glass and dentin interface led to the formation of an amorphous hydroxyapatite layer, similar to that of an inorganic component of the normal dentin. Moreover, BG/Ac was able to prevent the formation of cracks and degradation of collagen fibers caused by CO2 irradiation. Overall, this study supports that application of BG/Ac paste irradiated by high-power laser could represent an effective and long-lasting therapeutic approach for dentin hypersensitivity.

Potential Sustainable Slow-Release Fertilizers Obtained by Mechanochemical Activation of MgAl and MgFe Layered Double Hydroxides and K2HPO4.

This study describes the behavior of potential slow-release fertilizers (SRF), prepared by the mechanochemical activation of calcined Mg2Al-CO3 or Mg2Fe-CO3 layered double hydroxides (LDH) mixed with dipotassium hydrogen phosphate (K2HPO4). The effects of LDH thermal treatment on P/K release behavior were investigated. Characterizations of the inorganic composites before and after release experiments combined X-Ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The best release profile (<75% in 28 days and at least 75% release) was obtained for MgAl/K2HPO4 (9 h milling, 2:1 molar ratio, MR). Compared to readily used K2HPO4, milling orthophosphate into LDH matrices decreases its solubility and slows down its release, with 60% and 5.4% release after 168 h for MgAl/K2HPO4 and MgFe/K2HPO4 composites, respectively. Mechanochemical addition of carboxymethylcellulose to the LDH/K2HPO4 composites leads to a noticeable improvement of P release properties.

Mechanochemical conversion of chrysotile/K2HPO4 mixtures into potential sustainable and environmentally friendly slow-release fertilizers.

Chrysotile fibers pose a threat to public health due to their association relation to respiratory malignant lung disease such as cancer. For this reason, they must be stored and discarded appropriately, including after treatment, which raises costs. In the present study, insoluble chrysotile fibers were milled in solid state with highly soluble K2HPO4, destroying both structures, making the chrysotile nontoxic and generating a new material with potential use as sustainable slow-release fertilizer (SSRF) containing mainly K and P. Based on the mills, milling conditions and chrysotile/K2HPO4 molar ratios used, Mg originating from chrysotile fibers reacted with K and P from dibasic potassium phosphate and were transformed into MgKPO4·H2O, MgKPO4·6H2O and probably a mixture of amorphous SiO2/MgO. In this study, a zirconia planetary mill and high-energy ball mill were used, both of them produced SSRF. In conclusion, it was possible to synthesize high-value and extremely useful materials for agriculture using a harmful waste. The release rate can be tailored by controlling chrysotile/K2HPO4 molar ratios, grinding speed and time, which makes the process even more promising for farming applications.

Bioactive glass plus laser phototherapy as promise candidates for dentine hypersensitivity treatment.

Treatments for dentine hypersensitivity (DH) may produce positive effects, though do not have lasting results. We investigated the reparative potential of stem cells derived from deciduous teeth (SHEDs) in response to components delivered from substances used in the treatment of the DH, associated or not to laser phototherapy (LPT), to stimulate dentine formation. SHEDs were submitted to substances delivered from a laboratorial P-rich bioactive glass [57SiO2 -26CaO-17P2 O5 (wt %)] or a commercially available desensitizer (Gluma® Desensitizer), associated (or not) to LPT (InGAlP diode laser, 660 nm, 0.028 cm2 , 20 mW, 5 J/cm2 , 7 s, contact mode). Biomaterial characterization was performed by X-ray diffraction, scanning electron microscopy and the particle size was evaluated by dynamic light scattering. SHEDs proliferation and differentiation were analyzed by MTT and Alizarin Red staining, respectively. The conditioned media used in these tests were evaluated regarding their pH and the ionic concentration changes due to ions leached from the bioactive glass (BG). BG majority presented a non-crystalline solid structure and mixed particle sizes characterized by the agglomeration of nanoparticles. Cultures treated with BG alone or in association to LPT showed improved cell growth in relation to Gluma® (p < 0.05). Gluma® was cytotoxic in all tested conditions, regardless irradiated or not. BG associated to LPT induced intense mineral matrix formation. In conclusion, BG releases ionic dissolution products able to promote SHEDs differentiation. BG associated to LPT improves SHEDs proliferation and differentiation in vitro, and may be a promise therapeutic approach for the DH treatment. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 107-116, 2017.