Characterization of the fungal genus Sphaerellopsis associated with rust fungi: species diversity, host-specificity, biogeography, and in-vitro mycoparasitic events of S. macroconidialis on the southern corn rust, Puccinia polysora.

Sphaerellopsis species are putative hyperparasites of rust fungi and may be promising biological control agents (BCA) of rust diseases. However, few detailed studies limit potential BCA development in Sphaerellopsis. Here, we explored the biogeography, host-specificity, and species diversity of Sphaerellopsis and examined the early infection stage of one species, S. macroconidialis, to infer its trophic status. We randomly screened 5,621 rust specimens spanning 99 genera at the Arthur Fungarium for the presence of Sphaerellopsis. We identified 199 rust specimens infected with Sphaerellopsis species on which we conducted morphological and multi-locus phylogenetic analyses. Five Sphaerellopsis species were recovered, infecting a total of 122 rust species in 18 genera from 34 countries. Sphaerellopsis melampsorinearum sp. nov. is described as a new species based on molecular phylogenetic data and morphological features of the sexual and asexual morphs. Sphaerellopsis paraphysata was the most commonly encountered species, found on 77 rust specimens, followed by Sphaerellopsis macroconidialis on 56 and S. melampsorinearum on 55 examined specimens. The type species, Sphaerellopsis filum, was found on 12 rust specimens and Sphaerellopsis hakeae on a single specimen. We also recovered and documented for the first time, the sexual morph of S. macroconidialis, from a specimen collected in Brazil. Our data indicate that Sphaerellopsis species are not host specific and furthermore that most species are cosmopolitan in distribution. However, S. paraphysata is more abundant in the tropics, and S. hakeae may be restricted to Australia. Finally, we confirm the mycoparasitic strategy of S. macroconidialis through in-vitro interaction tests with the urediniospores of Puccinia polysora. Shortly after germination, hyphae of S. macroconidialis began growing along the germ tubes of P. polysora and coiling around them. After 12 days of co-cultivation, turgor loss was evident in the germ tubes of P. polysora, and appressorium-like structures had formed on urediniospores. The interaction studies indicate that Sphaerellopsis species may be more effective as a BCA during the initial stages of rust establishment.

Development of Bioactive Hybrid Poly(lactic acid)/Poly(methyl methacrylate) (PLA/PMMA) Electrospun Fibers Functionalized with Bioglass Nanoparticles for Bone Tissue Engineering Applications.

Hybrid scaffolds that are based on PLA and PLA/PMMA with 75/25, 50/50, and 25/75 weight ratios and functionalized with 10 wt.% of bioglass nanoparticles (n-BG) were developed using an electrospinning technique with a chloroform/dimethylformamide mixture in a 9:1 ratio for bone tissue engineering applications. Neat PLA and PLA/PMMA hybrid scaffolds were developed successfully through a (CF/DMF) solvent system, obtaining a random fiber deposition that generated a porous structure with pore interconnectivity. However, with the solvent system used, it was not possible to generate fibers in the case of the neat PMMA sample. With the increase in the amount of PMMA in PLA/PMMA ratios, the fiber diameter of hybrid scaffolds decreases, and the defects (beads) in the fiber structure increase; these beads are associated with a nanoparticle agglomeration, that could be related to a low interaction between n-BG and the polymer matrix. The Young's modulus of PLA/PMMA/n-BG decreases by 34 and 80%, indicating more flexible behavior compared to neat PLA. The PLA/PMMA/n-BG scaffolds showed a bioactive property related to the presence of hydroxyapatite crystals in the fiber surface after 28 days of immersion in a Simulated Body Fluids solution (SBF). In addition, the hydrolytic degradation process of PLA/PMMA/n-BG, analyzed after 35 days of immersion in a phosphate-buffered saline solution (PBS), was less than that of the pure PLA. The in vitro analysis using an HBOF-1.19 cell line indicated that the PLA/PMMA/n-BG scaffold showed good cell viability and was able to promote cell proliferation after 7 days. On the other hand, the in vivo biocompatibility evaluated via a subdermal model in BALC male mice corroborated the good behavior of the scaffolds in avoiding the generation of a cytotoxic effect and being able to enhance the healing process, suggesting that the materials are suitable for potential applications in tissue engineering.

Electrospun scaffolds based on a PCL/starch blend reinforced with CaO nanoparticles for bone tissue engineering.

Electrospun nanocomposite scaffolds with improved bioactive and biological properties were fabricated from a blend of polycaprolactone (PCL) and starch, and then combined with 5 wt% of calcium oxide (CaO) nanoparticles sourced from eggshells. SEM analyses showed scaffolds with fibrillar morphology and a three-dimensional structure. The hydrophilicity of scaffolds was improved with starch and CaO nanoparticles, which was evidenced by enhanced water absorption (3500 %) for 7 days. In addition, PCL/Starch/CaO scaffolds exhibited major degradation, with a mass loss of approximately 60 % compared to PCL/Starch and PCL/CaO. The PCL/Starch/CaO scaffolds decreased in crystallinity as intermolecular interactions between the nanoparticles retarded the mobility of the polymeric chains, leading to a significant increase in Young's modulus (ca. 60 %) and a decrease in tensile strength and elongation at break, compared to neat PCL. SEM-EDS, FT-IR, and XRD analyses indicated that PCL/Starch/CaO scaffolds presented a higher biomineralization capacity due to the ability to form hydroxyapatite (HA) in their surface after 28 days. The PCL/Starch/CaO scaffolds showed attractive biological performance, allowing cell adhesion and viability of M3T3-E1 preosteoblastic cells. In vivo analysis using a subdermal dorsal model in Wistar rats showed superior biocompatibility and improved resorption process compared to a pure PCL matrix. This biological analysis suggested that the PCL/Starch/CaO electrospun mats are suitable scaffolds for guiding the regeneration of bone tissue.

The low-FODMAP diet.

In this article we present a protocol for the use of the low-FODMAP diet in paediatric patients and review of the current evidence on its efficacy. These short-chain carbohydrates, which can be fermented by the intestinal microbiota, are found in a wide variety of foods, mainly of plant origin. The low-FODMAP diet is a therapeutic tool used for the management of gastrointestinal disorders such as irritable bowel syndrome. The sources we used were PubMed, Web of Science, Google Scholar and institutional websites. Following consumption of FODMAP-rich foods, a series of end products are generated that are not absorbed, giving rise to symptoms. Before starting a low-FODMAP diet, it is important to carry out a diagnostic evaluation including any applicable tests. Treatment is structured in 3 phases: elimination, reintroduction and personalization phase. In the first phase, FODMAP-rich foods are eliminated for 2-3 weeks. In the second phase, lasting 8 weeks, FODMAP-rich foods are gradually reintroduced. The last phase consists in customizing the diet according to individual tolerance. This article details which foods contain FODMAPs and possible substitutes. In addition, specific food diary/intake tracking and educational materials are provided in a series of appendices to facilitate adherence to the diet. Although most studies have been conducted in adults, there is also some evidence on the beneficial effects in the paediatric age group, with a reduction of symptoms, especially in patients with functional gastrointestinal disorders. Nevertheless, more research is required on the subject.

Removal of Mo(VI), Pb(II), and Cu(II) from wastewater using electrospun cellulose acetate/chitosan biopolymer fibers.

Environmentally friendly polymers such as cellulose acetate (CA) and chitosan (CS) were used to obtain electrospun fibers for Cu2+, Pb2+, and Mo6+ capture. The solvents dichloromethane (DCM) and dimethylformamide (DMF) allowed the development of a surface area of 148 m2 g-1 for CA fibers and 113 m2 g-1 for cellulose acetate/chitosan (CA/CS) fibers. The fibers were characterized by IR-DRIFT, SEM, TEM, CO2 sorption isotherms at 273 K, Hg porosimetry, TGA, stress-strain tests, and XPS. The CA/CS fibers had a higher adsorption capacity than CA fibers without affecting their physicochemical properties. The capture capacity reached 102 mg g-1 for Cu2+, 49.3 mg g-1 for Pb2+, and 13.1 mg g-1 for Mo6+. Furthermore, optimal pH, adsorption times qt, and C0 were studied for the evaluation of kinetic models and adsorption isotherms. Finally, a proposal for adsorbate-adsorbent interactions is presented as a possible capture mechanism where, in the case of Mo6+, a computational study is presented. The results demonstrate the potential to evaluate the fibers in tailings wastewater from copper mining.

Biological activity of lyophilized chitosan scaffolds with inclusion of chitosan and zinc oxide nanoparticles.

The constant demand for biocompatible and non-invasive materials for regenerative medicine in accidents and various diseases has driven the development of innovative biomaterials that promote biomedical applications. In this context, using sol-gel and ionotropic gelation methods, zinc oxide nanoparticles (NPs-ZnO) and chitosan nanoparticles (NPs-CS) were synthesized with sizes of 20.0 nm and 11.98 nm, respectively. These nanoparticles were incorporated into chitosan scaffolds through the freeze-drying method, generating a porous morphology with small (<100 µm), medium (100-200 µm), and large (200-450 µm) pore sizes. Moreover, the four formulations showed preliminary bioactivity after hydrolytic degradation, facilitating the formation of a hydroxyapatite (HA) layer on the scaffold surface, as evidenced by the presence of Ca (4%) and P (5.1%) during hydrolytic degradation. The scaffolds exhibited average antibacterial activity of F1 = 92.93%, F2 = 99.90%, F3 = 74.10%, and F4 = 88.72% against four bacterial strains: K. pneumoniae, E. cloacae, S. enterica, and S. aureus. In vivo, evaluation confirmed the biocompatibility of the functionalized scaffolds, where F2 showed accelerated resorption attributed to the NPs-ZnO. At the same time, F3 exhibited controlled degradation with NPs-CS acting as initiation points for degradation. On the other hand, F4 combined NPs-CS and NPs-ZnO, resulting in progressive degradation, reduced inflammation, and an organized extracellular matrix. All the results presented expand the boundaries in tissue engineering and regenerative medicine by highlighting the crucial role of nanoparticles in optimizing scaffold properties.

Uromyces savulescui on statice (Limonium sinuatum) in the Americas and reevaluation of its reported geographic range.

Limonium sinuatum (Plumbaginaceae) is the most commonly cultivated recognizable cut flower crop in the genus Limonium. It is known by several common names including statice and sea lavender, due to its lilac-colored flowers and the fact that it naturally inhabits mainly coastal areas (Mellesse et al, 2013). Limonium sinuatum is native to the Mediterranean, although as a popular garden plant, has been naturalized in other parts of the world including coastal areas of California (USDA NRCS 2020). Cultivated L. sinuatum is used in fresh and dry flower arrangements in the Americas, comprising approximately 20% of the floriculture cultivated area in Ecuador (Vega and Morales 2011; Abascal Cañas 2017). In December 2014, L. sinuatum plants in the public park "Baños del Inca" in Cajamarca, Peru (S 7 9'46"; W 78 27'53"), were found infected with a rust disease. The plants were scattered in the park but infection incidence was 100% as individual plants were all found to be infected (Fig 1). Based on the percentage of symptomatic areas, including the yellow halos around pustules, calculated with ImageJ (Collins, 2007) from field photographs, the disease severity was estimated to be 58.9% in average, ranging from 19.8% up to 90.0%. Uredinia were present on both sides of the leaves as well as on stems and were roundish, oblong, pulverulent, and cinnamon brown in color; urediniospores 25.5 to 35.0 × 22.5 to 31.0 µm, were globoid to ellipsoid; urediniospore walls were cinnamon-brown, 2.5 to 3.0 µm thick, densely verrucose, with 2 to 3 equatorial germ pores. Few telia were present on leaves; these were scattered roundish or oblong, and greyish in color; teliospores 26.5 to 41.0 × 16.0 to 25.0 µm, were ellipsoid to obovoid, mostly attenuated at the apex; teliospore walls were colorless, 2-3 µm thick at sides, and up to 10 µm thick at apex. Teliospores readily germinated in sori producing basidia and basidiospores (Fig. 2). The rust features and dimensions of rust spores are consistent with available descriptions of Uromyces savulescui Rayss (Guyot 1951; Vakalounakis and Malathrakis 1987). To confirm identity, a 576 bp region of the 28S subunit of the ribosomal DNA repeat was sequenced following previously published protocols and primers (Aime 2006, Aime et al. 2018). The resulting sequence (GenBank Accession No. OR291160) shared 99.83% (573/574 bp) identity with a sequence deposited as Uromyces limonii (DC.) Lev. (accession KY764194, BPI910295, Demers et al. unpublished) from L. sinuatum in Ethiopia. However, U. limonii produces orange uredinia, thin-walled yellow-orange urediniospores, teliospores with mostly light chestnut brown wall and infects different hosts (Savile and Conners 1951). It is likely that KY764194 represents a misannotated record of U. savulescui. While Koch's postulates can be a useful tool for establishing causality in certain infectious diseases, their use may be limited when it comes to rust diseases based on old herbarium specimens. In our case, due to the age of the specimen, which is almost nine years old, various other methods were employed to identify the pathogen. These methods included microscopic examination for morphological criteria of the urediniospores and teliospores, as well as molecular techniques like 28S rDNA sequencing. Rust disease on L. sinuatum has been previously reported in Ecuador but the causal agent was identified as a Puccinia sp. and reported that the rust was able to destroy entire plots in humid conditions (Vega and Morales 2011). Whether this report also represent U. savulescui is not certain, but given that the urediniospores of Puccinia species are generally 2-celled, it is unlikely. García-Hernández et al. (2008) reported U. limonii on Limonium spp. from Chile, and Coca (2020) also reported U. limonii on Limonium sp., from Bolivia. However, judging from the photomicrographs (Coca 2020), the rust in the latter report is definitely U. savulescui and not U. limonii. Uromyces savulescui has been previously reported from the Mediterranean region and the Canary Islands (Vakalounakis and Malathrakis 1987). To our knowledge there is no report of this rust in the Americas, excepting the probable misidentifications already listed herein. The specimen has been deposited in the Arthur Fungarium at Purdue University as PURN15037.

Biocompatibility Assessment of Polycaprolactone/Polylactic Acid/Zinc Oxide Nanoparticle Composites under In Vivo Conditions for Biomedical Applications.

The increasing demand for non-invasive biocompatible materials in biomedical applications, driven by accidents and diseases like cancer, has led to the development of sustainable biomaterials. Here, we report the synthesis of four block formulations using polycaprolactone (PCL), polylactic acid (PLA), and zinc oxide nanoparticles (ZnO-NPs) for subdermal tissue regeneration. Characterization by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) confirmed the composition of the composites. Additionally, the interaction of ZnO-NPs mainly occurred with the C=O groups of PCL occurring at 1724 cm-1, which disappears for F4, as evidenced in the FT-IR analysis. Likewise, this interaction evidenced the decrease in the crystallinity of the composites as they act as crosslinking points between the polymer backbones, inducing gaps between them and weakening the strength of the intermolecular bonds. Thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses confirmed that the ZnO-NPs bind to the carbonyl groups of the polymer, acting as weak points in the polymer backbone from where the different fragmentations occur. Scanning electron microscopy (SEM) showed that the increase in ZnO-NPs facilitated a more compact surface due to the excellent dispersion and homogeneous accumulation between the polymeric chains, facilitating this morphology. The in vivo studies using the nanocomposites demonstrated the degradation/resorption of the blocks in a ZnO-NP-dependant mode. After degradation, collagen fibers (Type I), blood vessels, and inflammatory cells continue the resorption of the implanted material. The results reported here demonstrate the relevance and potential impact of the ZnO-NP-based scaffolds in soft tissue regeneration.

Preparation and characterization of novel poly (lactic acid)/calcium oxide nanocomposites by electrospinning as a potential bone tissue scaffold.

Calcium oxide nanoparticles (n-CaO) ca. 22 nm were obtained from eggshell waste. The n-CaO was incorporated into the PLA matrix in 10 and 20 wt% of filler content by electrospinning process to get PLA/n-CaO fibers with homogenous morphology and diameter as a potential use in scaffold for bone tissue regeneration. The incorporation of n-CaO into PLA modifies the mechanical properties, having a reinforcement effect on the matrix. The Young modulus for PLA/n-CaO nanocomposites increased between 122 and 138 % concerning neat PLA fibers, showing a more rigid behavior. The PLA/n-CaO nanocomposite fibers showed in vitro bioactivity, capable of inducing the precipitation of hydroxyapatite (HA) layer in the fiber surface after seven days in SBF solution. The biocidal and biological properties of PLA/n-Cao with 20 wt% showed a 30 % reduction in bacterial viability against S. aureus and 11 % against E. coli after 6 h of bacterial exposure. Furthermore, the fibers did not show a cytotoxic effect on the bone marrow ST-2 cell line, allowing cell adhesion and proliferation in the RPMI medium. The PLA/n-CaO with 20 wt% of nanoparticles showed a higher capacity to promote osteogenic differentiation, significantly increasing the alkaline phosphatase (ALP) expression after seven days compared to PLA and cell control. The in vivo analysis corroborated the biocompatibility of the prepared scaffolds; the presence of n-CaO in PLA reduced the formation of fibrous encapsulation of the material, improving the healing process. These results validated using n-CaO to enhance the functionality of polymer matrices as a PLA, bringing bioactive, biocide, and biocompatible properties, opening a new and interesting route to develop new biomaterials as a scaffold for bone tissue engineering.

Predicting the Mitochondrial Toxicity of Small Molecules: Insights from Mechanistic Assays and Cell Painting Data.

Mitochondrial toxicity is a significant concern in the drug discovery process, as compounds that disrupt the function of these organelles can lead to serious side effects, including liver injury and cardiotoxicity. Different in vitro assays exist to detect mitochondrial toxicity at varying mechanistic levels: disruption of the respiratory chain, disruption of the membrane potential, or general mitochondrial dysfunction. In parallel, whole cell imaging assays like Cell Painting provide a phenotypic overview of the cellular system upon treatment and enable the assessment of mitochondrial health from cell profiling features. In this study, we aim to establish machine learning models for the prediction of mitochondrial toxicity, making the best use of the available data. For this purpose, we first derived highly curated datasets of mitochondrial toxicity, including subsets for different mechanisms of action. Due to the limited amount of labeled data often associated with toxicological endpoints, we investigated the potential of using morphological features from a large Cell Painting screen to label additional compounds and enrich our dataset. Our results suggest that models incorporating morphological profiles perform better in predicting mitochondrial toxicity than those trained on chemical structures alone (up to +0.08 and +0.09 mean MCC in random and cluster cross-validation, respectively). Toxicity labels derived from Cell Painting images improved the predictions on an external test set up to +0.08 MCC. However, we also found that further research is needed to improve the reliability of Cell Painting image labeling. Overall, our study provides insights into the importance of considering different mechanisms of action when predicting a complex endpoint like mitochondrial disruption as well as into the challenges and opportunities of using Cell Painting data for toxicity prediction.

Green composites based on thermoplastic starch reinforced with micro- and nano-cellulose by melt blending - A review.

Starch is a biodegradable biopolymer, a sustainable material that can replace conventional petrochemical-based plastics. However, starch has some limitations, as it must be processed by heating and treated mechanically with a plasticizer to become thermoplastic starch (TPS). Different variables such as mixing speeds, amount, and kind of plasticizers play a vital role in preparing TPS by melting. Despite this, the properties of the TPS are not comparable with those of traditional plastics. To overcome this limitation, microcellulose or nanocellulose is added to TPS by melt mixing, including the extrusion and internal mixing process, which enables large-scale production. This review aims to compile several studies that evaluate the effect of plasticizers, as well as the relevance of incorporating different cellulosic fillers of different dimensions on the properties of TPS obtained by melt mixing. Potential applications of these materials in food packaging, biomedical applications, and other opportunities are also described.

Effect of Electrospun PLGA/Collagen Scaffolds on Cell Adhesion, Viability, and Collagen Release: Potential Applications in Tissue Engineering.

The development of scaffolding obtained by electrospinning is widely used in tissue engineering due to porous and fibrous structures that can mimic the extracellular matrix. In this study, poly (lactic-co-glycolic acid) (PLGA)/collagen fibers were fabricated by electrospinning method and then evaluated in the cell adhesion and viability of human cervical carcinoma HeLa and NIH-3T3 fibroblast for potential application in tissue regeneration. Additionally, collagen release was assessed in NIH-3T3 fibroblasts. The fibrillar morphology of PLGA/collagen fibers was verified by scanning electron microscopy. The fiber diameter decreased in the fibers (PLGA/collagen) up to 0.6 µm. FT-IR spectroscopy and thermal analysis confirmed that both the electrospinning process and the blend with PLGA give structural stability to collagen. Incorporating collagen in the PLGA matrix promotes an increase in the material's rigidity, showing an increase in the elastic modulus (38%) and tensile strength (70%) compared to pure PLGA. PLGA and PLGA/collagen fibers were found to provide a suitable environment for the adhesion and growth of HeLa and NIH-3T3 cell lines as well as stimulate collagen release. We conclude that these scaffolds could be very effective as biocompatible materials for extracellular matrix regeneration, suggesting their potential applications in tissue bioengineering.

Fabrication and assessment of bifunctional electrospun poly(l-lactic acid) scaffolds with bioglass and zinc oxide nanoparticles for bone tissue engineering.

Electrospun scaffolds based on poly(l-lactic acid) (PLLA) with bioglass (n-BG) and zinc oxide (n-ZnO), and mixture of both, were developed to design bifunctional biomaterials with enhanced bioactive and biocidal properties. The presence of n-BG increased the fiber diameter of the pure PLA from 1.5 ± 0.3 µm to 3.0 ± 0.8 µm for 20 wt%. ZnO and the mixed nanoparticles did not significantly affect the morphology. The mechanical properties decreased with the presence of nanoparticles. Scaffolds based on PLA/n-BG promoted hydroxyapatite (HA) formation in simulated body fluid (SBF) that was inhibited with the presence of ZnO. Notably, mixed particles produced bioactivity although at longer times. The incorporation of n-ZnO produced a biocidal capacity against S. aureus in the polymeric scaffold, reaching a viability reduction of 60 % after 6 h of exposure. When both types of nanoparticles were combined, the bacterial viability reduction was 30 %. Pure PLA scaffolds and the composites with n-BG showed good ST-2 bone marrow-derived cell line viability, scaffolds with n-BG (pure or mixture) presented lower viability. Results validated the use of both n-BG and n-ZnO fillers for the development of novel bifunctional PLA-based scaffolds with both bioactive and biocidal properties for bone tissue engineering applications.

Effect of Gelatin Coating and GO Incorporation on the Properties and Degradability of Electrospun PCL Scaffolds for Bone Tissue Regeneration.

Polymer-based nanocomposites such as polycaprolactone/graphene oxide (PCL/GO) have emerged as alternatives for bone tissue engineering (BTE) applications. The objective of this research was to investigate the impact of a gelatin (Gt) coating on the degradability and different properties of PCL nanofibrous scaffolds fabricated by an electrospinning technique with 1 and 2 wt% GO. Uniform PCL/GO fibers were obtained with a beadless structure and rough surface. PCL/GO scaffolds exhibited an increase in their crystallization temperature (Tc), attributed to GO, which acted as a nucleation agent. Young's modulus increased by 32 and 63% for the incorporation of 1 and 2 wt% GO, respectively, in comparison with neat PCL. A homogeneous Gt coating was further applied to these fibers, with incorporations as high as 24.7 wt%. The introduction of the Gt coating improved the hydrophilicity and degradability of the scaffolds. Bioactivity analysis revealed that the hydroxyapatite crystals were deposited on the Gt-coated scaffolds, which made them different from their uncoated counterparts. Our results showed the synergic effect of Gt and GO in enhancing the multifunctionality of the PCL, in particular the degradability rate, bioactivity, and cell adhesion and proliferation of hGMSC cells, making it an interesting biomaterial for BTE.

Chitosan-Polyvinyl Alcohol Nanocomposites for Regenerative Therapy.

Tissue accidents provide numerous pathways for pathogens to invade and flourish, causing additional harm to the host tissue while impeding its natural healing and regeneration. Essential oils (EOs) exhibit rapid and effective antimicrobial properties without promoting bacterial resistance. Clove oils (CEO) demonstrate robust antimicrobial activity against different pathogens. Chitosan (CS) is a natural, partially deacetylated polyamine widely recognized for its vast antimicrobial capacity. In this study, we present the synthesis of four membrane formulations utilizing CS, polyvinyl alcohol (PVA), and glycerol (Gly) incorporated with CEO and nanobioglass (n-BGs) for applications in subdermal tissue regeneration. Our analysis of the membranes' thermal stability and chemical composition provided strong evidence for successfully blending polymers with the entrapment of the essential oil. The incorporation of the CEO in the composite was evidenced by the increase in the intensity of the band of C-O-C in the FTIR; furthermore, the increase in diffraction peaks, as well as the broadening, provide evidence that the introduction of CEO perturbed the crystal structure. The morphological examination conducted using scanning electron microscopy (SEM) revealed that the incorporation of CEO resulted in smooth surfaces, in contrast to the porous morphologies observed with the n-BGs. A histological examination of the implanted membranes demonstrated their biocompatibility and biodegradability, particularly after a 60-day implantation period. The degradation process of more extensive membranes involved connective tissue composed of type III collagen fibers, blood vessels, and inflammatory cells, which supported the reabsorption of the composite membranes, evidencing the material's biocompatibility.

Comparison of Two Bovine Commercial Xenografts in the Regeneration of Critical Cranial Defects.

Autologous bone is the gold standard in regeneration processes. However, there is an endless search for alternative materials in bone regeneration. Xenografts can act as bone substitutes given the difficulty of obtaining bone tissue from patients and before the limitations in the availability of homologous tissue donors. Bone neoformation was studied in critical-size defects created in the parietal bone of 40 adult male Wistar rats, implanted with xenografts composed of particulate bovine hydroxyapatite (HA) and with blocks of bovine hydroxyapatite (HA) and Collagen, which introduces crystallinity to the materials. The Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated the carbonate and phosphate groups of the hydroxyapatite and the amide groups of the collagen structure, while the thermal transitions for HA and HA/collagen composites established mainly dehydration endothermal processes, which increased (from 79 °C to 83 °C) for F2 due to the collagen presence. The xenograft's X-ray powder diffraction (XRD) analysis also revealed the bovine HA crystalline structure, with a prominent peak centered at 32°. We observed macroporosity and mesoporosity in the xenografts from the morphology studies with heterogeneous distribution. The two xenografts induced neoformation in defects of critical size. Histological, histochemical, and scanning electron microscopy (SEM) analyses were performed 30, 60, and 90 days after implantation. The empty defects showed signs of neoformation lower than 30% in the three periods, while the defects implanted with the material showed partial regeneration. InterOss Collagen material temporarily induced osteon formation during the healing process. The results presented here are promising for bone regeneration, demonstrating a beneficial impact in the biomedical field.

Histological Evaluation of Cassava Starch/Chicken Gelatin Membranes.

The use of biopolymers for tissue engineering has recently gained attention due to the need for safer and highly compatible materials. Starch is one of the most used biopolymers for membrane preparation. However, incorporating other polymers into starch membranes introduces improvements, such as better thermal and mechanical resistance and increased water affinity, as we reported in our previous work. There are few reports in the literature on the biocompatibility of starch/chicken gelatin composites. We assessed the in vivo biocompatibility of the five composites (T1-T5) cassava starch/gelatin membranes with subdermal implantations in biomodels at 30, 60, and 90 days. The FT-IR spectroscopy analysis demonstrated the main functional groups for starch and chicken gelatin. At the same time, the thermal study exhibited an increase in thermal resistance for T3 and T4, with a remaining mass (~15 wt.%) at 800 °C. The microstructure analysis for the T2-T4 demonstrated evident roughness changes with porosity presence due to starch and gelatin mixture. The decrease in the starch content in the composites also decreased the gelatinization heats for T3 and T4 (195.67, 196.40 J/g, respectively). Finally, the implantation results demonstrated that the formulations exhibited differences in the degradation and resorption capacities according to the starch content, which is easily degraded by amylases. However, the histological results showed that the samples demonstrated almost complete reabsorption without a severe immune response, indicating a high in vivo biocompatibility. These results show that the cassava starch/chicken gelatin composites are promising membrane materials for tissue engineering applications.

Biocompatibility Assessment of Polylactic Acid (PLA) and Nanobioglass (n-BG) Nanocomposites for Biomedical Applications.

Scaffolds based on biopolymers and nanomaterials with appropriate mechanical properties and high biocompatibility are desirable in tissue engineering. Therefore, polylactic acid (PLA) nanocomposites were prepared with ceramic nanobioglass (PLA/n-BGs) at 5 and 10 wt.%. Bioglass nanoparticles (n-BGs) were prepared using a sol-gel methodology with a size of ca. 24.87 ± 6.26 nm. In addition, they showed the ability to inhibit bacteria such as Escherichia coli (ATCC 11775), Vibrio parahaemolyticus (ATCC 17802), Staphylococcus aureus subsp. aureus (ATCC 55804), and Bacillus cereus (ATCC 13061) at concentrations of 20 w/v%. The analysis of the nanocomposite microstructures exhibited a heterogeneous sponge-like morphology. The mechanical properties showed that the addition of 5 wt.% n-BG increased the elastic modulus of PLA by ca. 91.3% (from 1.49 ± 0.44 to 2.85 ± 0.99 MPa) and influenced the resorption capacity, as shown by histological analyses in biomodels. The incorporation of n-BGs decreased the PLA crystallinity (from 7.1% to 4.98%) and increased the glass transition temperature (Tg) from 53 °C to 63 °C. In addition, the n-BGs increased the thermal stability due to the nanoparticle's intercalation between the polymeric chains and the reduction in their movement. The histological implantation of the nanocomposites and the cell viability with HeLa cells higher than 80% demonstrated their biocompatibility character with a greater resorption capacity than PLA. These results show the potential of PLA/n-BGs nanocomposites for biomedical applications, especially for long healing processes such as bone tissue repair and avoiding microbial contamination.

Electrospun fibers of poly (lactic acid) containing bioactive glass and magnesium oxide nanoparticles for bone tissue regeneration.

Electrospun fibers of poly (lactic acid) (PLA) containing 10 and 20 wt% of bioactive glass (n-BG) and magnesium oxide (n-MgO) nanoparticles of ca. 27 and 23 nm respectively, were prepared toward to application in bone tissue engineering. The addition of both nanoparticles into the PLA will produce a synergic effect increasing its bioactivity and antimicrobial behavior. Neat PLA scaffold and the composites with MgO showed an average fiber diameter of 1.7 ± 0.6 µm, PLA/n-BG and PLA/n-BG/n-MgO fibers presented a significant diameter increase reaching values of ca. 3.1 ± 0.8 µm. Young's modulus of the electrospun scaffolds was affected by the direct presence of the particle and scaffold morphologies. All the composites having n-BG presented bioactivity through the precipitation of hydroxyapatite structures on the surface. Although n-MgO did not add bioactivity to the PLA fibers, they were able to render antimicrobial characteristics reducing the S. aureus viability around 30%, although an effect on E. coli strain was not observed. PLA/n-BG nanocomposites did not display any significant antimicrobial behavior. The different composites increased the alkaline phosphatase (ALP) expression as compared with pure PLA barely affecting the cell viability, meaning a good osteoblastic phenotype expression capacity, with PLA/n-BG presenting the highest osteoblastic expression.