Candidate genes involved in biosynthesis and degradation of the main extracellular matrix polysaccharides of brown algae and their probable evolutionary history.

BACKGROUND: Brown algae belong to the Stramenopiles phylum and are phylogenetically distant from plants and other multicellular organisms. This independent evolutionary history has shaped brown algae with numerous metabolic characteristics specific to this group, including the synthesis of peculiar polysaccharides contained in their extracellular matrix (ECM). Alginates and fucose-containing sulphated polysaccharides (FCSPs), the latter including fucans, are the main components of ECMs. However, the metabolic pathways of these polysaccharides remain poorly described due to a lack of genomic data. RESULTS: An extensive genomic dataset has been recently released for brown algae and their close sister species, for which we previously performed an expert annotation of key genes involved in ECM-carbohydrate metabolisms. Here we provide a deeper analysis of this set of genes using comparative genomics, phylogenetics analyses, and protein modelling. Two key gene families involved in both the synthesis and degradation of alginate were suggested to have been acquired by the common ancestor of brown algae and their closest sister species Schizocladia ischiensis. Our analysis indicates that this assumption can be extended to additional metabolic steps, and thus to the whole alginate metabolic pathway. The pathway for the biosynthesis of fucans still remains biochemically unresolved and we also investigate putative fucosyltransferase genes that may harbour a fucan synthase activity in brown algae. CONCLUSIONS: Our analysis is the first extensive survey of carbohydrate-related enzymes in brown algae, and provides a valuable resource for future research into the glycome and ECM of brown algae. The expansion of specific families related to alginate metabolism may have represented an important prerequisite for the evolution of developmental complexity in brown algae. Our analysis questions the possible occurrence of FCSPs outside brown algae, notably within their closest sister taxon and in other Stramenopiles such as diatoms. Filling this knowledge gap in the future will help determine the origin and evolutionary history of fucan synthesis in eukaryotes.

Little alginates synthesized in EPS: Evidences from high-throughput community and metagenes.

As a significant structure in activated sludge, extracellular polymeric substances (EPS) hold considerable value regarding resource recovery and applications. The present study aimed to elucidate the relationship between the microbial community and the composition and properties of EPS. A biological nutrient removal (BNR) reactor was set up in the laboratory and controlled under different solid retention times (SRT), altering microbial species within the system. Then EPS was extracted from activated and analyzed by chemical and spectroscopic methods. High-throughput sequencing and metagenomic approaches were employed to investigate bacterial community and metabolic pathways. The results showed that lower SRT with a higher abundance of the family-level Proteobacteria (27.7%-53.5%) favored EPS synthesis, while another dominant group Bacteroidetes (20.0%-32.6%) may not significantly affect EPS synthesis. Furthermore, the abundance of alginates-producing bacteria including Pseudomonas spp. and Azotobacter vinelandii was only 2.53%-6.76% and 1.98%-6.34%, respectively. The alginate synthesis pathway genes Alg8 and Alg44 were also present at very low levels (0.05‱-0.11‱, 0.01‱-0.02‱, respectively). Another important gene related to alginates operons, AlgK, was absent across all the SRT-operated reactors. These findings suggest an impossible and incomplete alginate synthesis pathway within sludge. In light of these results, it can be concluded that EPS does not necessarily contain alginate components.

Surface Modification of Dentin Powder With Alginate and Evaluation of Its Effects on the Viability and Proliferation of Dental Pulp Stem Cells (In Vitro), Its Biocompatibility (In Vivo).

INTRODUCTION: This study aimed to synthesize dentin powder surface modified with alginate, a potential substance for dental pulp regeneration, and evaluate its effects on the viability and proliferation of human dental pulp stem cells in vitro and its biocompatibility in vivo. METHODS: In the in vitro phase, dentin powder was synthesized in 3 size groups (150-250 µm, 250-500 µm, and 500-1000 µm) after demineralization and atelopeptidization which is used to remove dentin collagen telopeptides and eliminate host immune response. Surface modification with alginate was performed and followed by field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and cell viability and proliferation testing for 14 days with human dental pulp stem cells studied. In the in vivo phase, dentin powders were implanted in rat calvarial defects for 8 weeks, and histologic analysis was conducted. All nonparametric data were analyzed with the Kruskal-Wallis test, and all the quantitative data were analyzed by 1-way analysis of variance using SPSS, and P < .05 was considered statistically significant. RESULTS: Demineralization and atelopeptidization were successful in all groups. Cell viability was optimal and equal (P > .05) in all groups. The 500- to 1000-µm group exhibited significantly higher cell proliferation (P < .05). Histologic assessment shows acceptable biocompatibility in all groups; the angiogenesis score was significantly greater in both 250-500 and 500-1000, and minimal inflammatory response was noted in the 500- to 1000-µm group, and the amount of newly formed bone in this group was higher than other groups. CONCLUSIONS: Surface modification of demineralized and atelopeptidized dentin powder with alginate enhanced surface physical properties and cell proliferation while showing great biocompatibility within tissue and reducing the host immune response. These findings hold promise for dentin-pulp complex regeneration.

Correction: Left Ventricular Geometry and Angiogenesis Improvement in Rat Chronic Ischemic Cardiomyopathy following Injection of Encapsulated Mesenchymal Stem Cells.

In this article published in Cell J, Vol 24, No 12, 2022, on pages 741-747, the authors found that there was some mistakes in the Table 1 and we have corrected them in the following table. The authors would like to apologize for any inconvenience.

A Systematic Review on the Efficacy and Safety of Alginate-based Liquid Formulations in Reducing Gastroesophageal Reflux in Neonates and Infants.

Background: Neonates and infants experience gastroesophageal reflux as manifested through vomiting, reflux, and coughing. The complaint from many caregivers begins around the 2nd or 3rd month of life and subside around the 6th month of infancy. The standard of care has not been established and treatment options are limited owing to the pharmacological interventions that are deemed safe and effective. Alginate-based formulations, a widely used product in adults such as Gaviscon™, have been explored as another option to treat gastroesophageal reflux. Objectives: To determine the safety and efficacy of alginate-based formulations in reducing symptoms of gastroesophageal reflux in neonates and infants. Methods: An electronic search was conducted for randomized control trials in MEDLINE via PubMed, Herdin Plus, Cochrane Central Register of Controlled Trials, SCOPUS, and Clinical Trials Registry. The search terms were "gastroesophageal reflux," "acid reflux," "neonates," "newborn," "infants," "baby," "babies,", and "alginate." Two review authors independently assessed the available full text articles and a third author intervened to settle the discussion. Results: Two studies were identified and included in this study. Due to the difference in the period of measurement of the trials, a meta-analysis was not pursued. However, a systematic review was still conducted. The two studies suggest a significant improvement of symptoms with alginate-based liquid formulations as intervention. No significant adverse events have been noted making this treatment option generally safe for use in infants. Conclusion: There is insufficient evidence to conclude that alginate-based formulations ultimately help decrease gastroesophageal reflux in neonates and infants, but initial trials show promising results. There is also insufficient data to conclude the safety profile of this treatment option given the small sample.

Encapsulation in Alginates Hydrogels and Controlled Release: An Overview.

This review aims to gather the current state of the art on the encapsulation methods using alginate as the main polymeric material in order to produce hydrogels ranging from the microscopic to macroscopic sizes. The use of alginates as an encapsulation material is of growing interest, as it is fully bio-based, bio-compatible and bio-degradable. The field of application of alginate encapsulation is also extremely broad, and there is no doubt it will become even broader in the near future considering the societal demand for sustainable materials in technological applications. In this review, alginate's main properties and gelification mechanisms, as well as some factors influencing this mechanism, such as the nature of the reticulation cations, are first investigated. Then, the capacity of alginate gels to release matter in a controlled way, from small molecules to micrometric compounds, is reported and discussed. The existing techniques used to produce alginates beads, from the laboratory scale to the industrial one, are further described, with a consideration of the pros and cons with each techniques. Finally, two examples of applications of alginate materials are highlighted as representative case studies.

Comparison of dental dimensions in models developed with digital procedures and plaster models / Comparación de dimensiones dentales en modelos desarrollados con procedimientos digitales y modelos en yeso

Aim: This study aimed to collect evidence on the validity and reliability of measurements obtained from digital impression techniques. Materials and Methods: This comparative study was conducted on 31 patients. Intraoral scanner was applied to all patients. For each patient, an alginate impression of the upper maxilla was taken and later the 3D digital model was extracted by dental cone-beam computed tomography (CBCT). For preparation of plaster models, alginate impressions were taken and immediately poured with dental stone. In the next stage, a comparison was performed among the intraoral scanner, CBCT, and plaster models in terms of tooth size, dental width, and intra-arch dimensions. Results: Measuring tooth size and intra-arch dimensions in digital images obtained from intraoral scanner and CBCT were in most cases lower than the results obtained in the plaster models but the differences between digital techniques and plaster models are not clinically noticeable. Conclusions: Digital systems including intraoral scanner and CBCT are acceptable for clinical use in terms of accuracy.

Objetivo: Este estudio tuvo como objetivo recopilar evidencia sobre la validez y confiabilidad de las mediciones obtenidas a partir de técnicas de impresión digital. Materiales y Métodos: Este estudio comparativo se realizó en 31 pacientes. A todos los pacientes se les aplicó escáner intraoral. Para cada paciente, se tomó una impresión de alginato del maxilar superior y posteriormente se extrajo el modelo digital 3D mediante Tomografía computarizada de haz cónico (CBCT) dental. Para la preparación de los modelos de yeso se tomaron impresiones de alginato y se vertieron inmediatamente con yeso dental. En la siguiente etapa, se realizó una comparación entre el escáner intraoral, CBCT y los modelos de yeso en términos de tamaño de diente, ancho dental y dimensiones intraarcada. Discusión: Se encontró que la apariencia microscópica de las células fusiformes era comparable en ambos grupos. Los resultados de la citometría de flujo demostraron expresiones comparables en ambos grupos, siendo las muestras positivas para CD90, CD73, CD105, HLA ABC y negativas para CD34, CD45 y HLA DR. Hubo variaciones en la expresión de los marcadores cuando se evaluaron los potenciales de diferenciación. Conclusión: Los sistemas digitales como el escáner intraoral y el CBCT son aceptables para uso clínico en términos de precisión.

Development of a Binderless Particleboard from Brown Seaweed Sargassum spp.

Since 2010, huge quantities of Sargassum spp. algae have been proliferating in the Atlantic Ocean and stranding on Caribbean beaches, causing major economic, environmental, and health problems. In this study, an innovative high-density binderless particleboard was developed using uniaxial thermo-compression coupled with a cooling system. The raw material consisted of ground Sargassum seaweeds pre-treated by twin-screw extrusion with water to remove sea salt. The raw material and the particleboards were produced by using various analytical techniques such as Dynamic Vapor Sorption (DVS), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), or Thermogravimetric Analysis (TGA). The experimental conditions for thermo-compression (temperature, pressure, time) were evaluated. The best thermo-compression conditions tested were 200 °C, 40 MPa pressure for 7.5 min. This resulted in a particleboard with high density (up to 1.63 ± 0.02 g/cm3) and high flexural strength/modulus (up to 32.3 ± 1.8 MPa/6.8 ± 0.2 GPa, respectively), but a low water contact angle of 38.9° ± 3.5°. Thermal analyses revealed the effect of alginates on the mechanical properties of particleboards. This work opens the door to a new way of adding value to Sargassum seaweed, using the whole algae with minimal pre-treatment.

Fucus vesiculosus-Rich Extracts as Potential Functional Food Ingredients: A Holistic Extraction Approach.

Brown macroalgae are rich sources of nutrients and health-promoting compounds. Nevertheless, their consumption is still limited by their strong organoleptic characteristics, thus requiring the development of extraction strategies to profit from their nutritional value. To fulfil this, two sequential extraction approaches were developed, differing in the solvent used in the first extraction step, water in approach 1 or food-grade ethanol in approach 2, to obtain economic and affordable extracts rich in specific compounds from Fucus vesiculosus. The use of water in the first step of extraction allowed us to recover water-soluble phlorotannins, laminarans and mannuronic-rich alginates, making the subsequent 70% ethanol extract richest in fucoxanthin (0.07% algae DW), and the hot water fractions purest in fucoidans and alginates with a lower mannuronic-to-guluronic (M/G) ratio (2.91). Conversely, when beginning extraction procedures with 96% ethanol, the recovered yields of phlorotannins increased (0.43 g PGE/100 g algae DW), but there was a concomitant seven-fold decrease in the recovery of fucoxanthin in the subsequent 70% ethanol extract. This approach also led to less pure hot water fractions containing fucoidans, laminarans and alginates with a higher M/G ratio (5.50). Overall, this work unveiled the potential of the first extraction steps in sustainable and holistic cascade strategies to modulate the composition of food-grade extracts, creating prospects of their application as tailored functional ingredients in food products.

A comparison study: The use of digital and conventional impression techniques in dental hygiene education.

PURPOSE/OBJECTIVES: The study aimed to assess the applicability of digital intraoral scanning in dental hygiene education and compare the quality, efficiency, and ease of use to conventional impression techniques. METHODS: Twenty-eight first-year dental hygiene students (DH1) at UTHealth Houston School of Dentistry (UTSD) participated in this 2022 study. Each student participated in two 4-h lab sessions. Students took traditional alginate impressions and digital intraoral scans using Planmeca Romexis on standardized teeth during the first and second sessions. Both techniques were assessed by faculty for quality and efficiency using a standardized rubric. Participants completed a post-survey providing insight into their perceptions of both techniques and ease of use. RESULTS: The study had 100% participation in the lab sessions and survey responses (N = 28). The results showed digital scanning produced a statistically higher quality product than conventional alginate impressions (p = 0.023). The study found no statistical difference in the efficiency between the two methods. The majority of students (82%) agreed that digital intraoral scanning was easy to use (p = 0.001), and 89% agreed they would use digital intraoral scanning in clinical courses to help with patient care (p = 0.03). CONCLUSION: In this study, dental hygiene students with limited clinical experience learned new technology and used it to produce quality impressions compared to the conventional technique, indicating the value of introducing digital dentistry early in dental hygiene education.

Photochromic biomaterials: Synthesis and fluorescence properties of spiroxanthenes-grafted alginate derivatives.

Herein, we reported a general and green synthetic strategy for photochromic functional alginate derivatives grafting with isoindolinone spiroxanthenes. Under mild condition, diverse 2-aminoalkyl isoindolinone spiroxanthene derivatives have been prepared from organic photochromic isobenzofuranone spiroxanthenes (including rhodamine B, rhodamine 6G and fluorescein), and grafted on alginate chains through amidation reaction using diamine as a linkage with water as a green solvent at room temperature. The photochromic properties of the fluorophores-modified polymers and the effect of pH value have been explored. Under acid conditions, the spiroisoindolinone rings of alginate derivatives are opened resulting in showing absorption bands and fluorescence with orange to green emission, while the alginate derivatives turned to colourless under basic conditions which is reversibly. In addition to biodegradability and biocompatibility, the polymers exhibit good film-forming properties simultaneously. The films and fibers produced from the alginate derivatives also project good fluorescence properties.

In-process epimerisation of alginates from Saccharina latissima, Alaria esculenta and Laminaria hyperborea.

Alginates are valued in many industries, due to their versatile properties. These polysaccharides originate from brown algae (Phaeophyceae) and some bacteria of the Azotobacter and Pseudomonas genera, consisting of 1 â†’ 4 linked ß-d-mannuronic acid (M), and its C5-epimer α-l-guluronic acid (G). Several applications rely on a high G-content, which confers good gelling properties. Because of its high natural G-content (FG = 0.60-0.75), the alginate from Laminaria hyperborea (LH) has sustained a thriving industry in Norway. Alginates from other sources can be upgraded with mannuronan C-5 epimerases that convert M to G, and this has been demonstrated in many studies, but not applied in the seaweed industry. The present study demonstrates epimerisation directly in the process of alginate extraction from cultivated Saccharina latissima (SL) and Alaria esculenta (AE), and the lamina of LH. Unlike conventional epimerisation, which comprises multiple steps, this in-process protocol can decrease the time and costs necessary for alginate upgrading. In-process epimerisation with AlgE1 enzyme enhanced G-content and hydrogel strength in all examined species, with the greatest effect on SL (FG from 0.44 to 0.76, hydrogel Young's modulus from 22 to 34 kPa). As proof of concept, an upscaled in-process epimerisation of alginate from fresh SL was successfully demonstrated.

A new hydroxyapatite-alginate-gelatin biocomposite favor bone regeneration in a critical-sized calvarial defect model

Abstract This study aimed to evaluate the osteogenic potential of hydroxyapatite (HA), Alginate (Alg), and Gelatine (Gel) composite in a critical-size defect model in rats. Twenty-four male rats were divided into three groups: a negative control with no treatment (Control group), a positive control treated with deproteinized bovine bone mineral (DBBM group), and the experimental group treated with the new HA-Alg-Gel composite (HA-Alg-Gel group). A critical size defect (8.5mm) was made in the rat's calvaria, and the bone formation was evaluated by in vivo microcomputed tomography analysis (µCT) after 1, 15, 45, and 90 days. After 90 days, the animals were euthanized and histological and histomorphometric analyses were performed. A higher proportion of mineralized tissue/biomaterial was observed in the DBBM group when compared to the HA-Alg-Gel and Control groups in the µCT analysis during all analysis periods. However, no differences were observed in the mineralized tissue/biomaterial proportion observed on day 1 (immediate postoperative) in comparison to later periods of analysis in all groups. In the histomorphometric analysis, the HA-Alg-Gel and Control groups showed higher bone formation than the DBBM group. Moreover, in histological analysis, five samples of the HA-Alg-Gal group exhibited formed bone spicules adjacent to the graft granules against only two of eight samples in the DBBM group. Both graft materials ensured the maintenance of defect bone thickness, while a tissue thickness reduction was observed in the control group. In conclusion, this study demonstrated the osteoconductive potential of HA-Alg-Gel bone graft by supporting new bone formation around its particles.

Resumo Este estudo teve como objetivo avaliar o potencial osteogênico de um compósito de hidroxiapatita (HA), alginato (Alg) e gelatina (Gel) em um modelo de defeito de tamanho crítico em ratos. Vinte e quatro ratos machos foram divididos em três grupos: um controle negativo sem tratamento (grupo controle), um controle positivo tratado com osso bovino desproteinizado (grupo DBBM) e o grupo experimental tratado com o novo compósito HA-Alg-Gel (grupo HA-Alg-Gel). Um defeito de tamanho crítico (8,5mm) foi feito na calvária dos ratos, e a formação óssea foi avaliada por análise de microtomografia computadorizada in vivo (µCT) após 1, 15, 45 e 90 dias. Após 90 dias, os animais foram eutanasiados e análises histológicas e histomorfométricas foram realizadas. Uma maior proporção de tecido mineralizado/biomaterial foi observada no grupo DBBM quando comparado aos grupos HA-Alg-Gel e controle na análise de µCT durante todos os períodos de análise. Entretanto, não foram observadas diferenças na proporção tecido mineralizado/biomaterial no dia 1 (pós-operatório imediato) em relação aos períodos posteriores de análise em todos os grupos. Na análise histomorfométrica, os grupos HA-Alg-Gel e controle apresentaram maior formação óssea do que o grupo DBBM. Além disso, na análise histológica, cinco amostras do grupo HA-Alg-Gal exibiram espículas ósseas formadas adjacentes aos grânulos do enxerto contra apenas duas das oito amostras do grupo DBBM. Ambos os materiais de enxerto garantiram a manutenção da espessura óssea do defeito, enquanto uma redução da espessura do tecido foi observada no grupo controle. Em conclusão, este estudo demonstrou o potencial osteocondutor do enxerto ósseo de HA-Alg-Gel, promovendo a formação de osso novo ao redor das suas partículas.

Bacterial nanocellulose/calcium alginate hydrogel for the treatment of burns

Purpose: Bacterial cellulose (BC) has shown high capacity for the treatment of wounds and burns, providing a moisty environment. Calcium alginate can be associated with BC to create gels that aid in wound debridement and contribute to appropriate wound healing. This study is aimed at characterizing and evaluating the use of bacterial cellulose/alginate gel in skin burns in rats. Methods: Cellulose and cellulose/alginate gels were compared regarding the capacity of liquid absorption, moisture, viscosity, and potential cytotoxicity. The 2nd degree burns were produced using an aluminum metal plate (2.0cm) at 120ºC for 20s on the back of rats. The animals were divided into non-treated, CMC(Carboxymethylcellulose), Cellulose(CMC with bacterial cellulose), and Cellulose/alginate(CMC with bacterial cellulose and alginate). The animals received topical treatment 3 times/week. Biochemical (MPO, NAG and oxidative stress), histomorphometry and immunohistochemical assays (IL-1ß IL-10 and VEGF) were conducted on the 14th, 21st, 28th, and 35th days. Results: Cellulose/Alginate gel showed higher absorption capacity and viscosity compared to Cellulose gel, with no cytotoxic effects. Cellulose/alginate presented lower MPO values, a higher percentage of IL-10, with greater and balanced oxidative stress profile. Conclusions: The use of cellulose/alginate gel reduced neutrophils and macrophage activation and showed greater anti-inflammatory response, which can contribute to healing chronic wounds and burns.

Is it Always Laryngopharyngeal Reflux? How Voice Disorders Can Manifest as LPR

Introduction: Laryngopharyngeal reflux (LPR) manifests with a constellation of common throat symptoms and inconclusive signs on laryngoscopic exam. It is a diagnosis, often made clinically, that can lead to prescriptions of proton pump inhibitors that are unnecessary and potentially harmful. Glottic insufficiency (GI) and the accompanying hyperfunctional laryngeal behaviors can also present with similar, common throat complaints that may or may not include a qualitative change to the voice. Methods: This is a reflection article. It is written to summarize, explain, and support with evidence the opinion of the author on the topic of how symptoms of voice disorders can easily be mistaken for symptoms of LPR. The offered reflection is based on his experience, research and the available literature. Reflection: This article intends to explore the similarities between GI and LPR, how to ultimately differentiate them and how to approach treatment with a broader differential diagnosis. Conclusion: LPR and GI can present with identical, vague throat, and voice symptoms. Empiric medication trials, behavioral interventions and objective laryngovideostroboscopy, impedance-based reflux, and esophageal motility testing may all be needed, sometimes in a trial and error fashion, to correctly diagnose and treat a patient's symptoms.

Introducción: El reflujo laríngeo-faríngeo (LPR, por sus siglas en inglés) se manifiesta con una serie de síntomas comunes en la garganta y signos no concluyentes en el examen larinoscópico. Es un diagnóstico que a menudo se realiza clínicamente y que puede llevar a la prescripción de inhibidores de la bomba de protones que son innecesarios y potencialmente perjudiciales. La insuficiencia glótica (IG) y los comportamientos laríngeos hiperfuncionales que la acompañan también pueden presentar síntomas de garganta comunes similares, que pueden o no incluir un cambio cualitativo en la voz. Métodos: Este es un artículo de reflexión. Está escrito para resumir, explicar y respaldar con evidencia la opinión del autor sobre cómo los síntomas de los trastornos de la voz pueden confundirse fácilmente con los síntomas del LPR. La reflexión ofrecida se basa en su experiencia, investigación y la literatura disponible. Reflexión: Este artículo tiene la intención de explorar las similitudes entre la IG y el LPR, cómo diferenciarlos finalmente y cómo abordar el tratamiento con un diagnóstico diferencial más amplio. Conclusión: El LPR y la IG pueden presentar síntomas idénticos y vagos en la garganta y la voz. Puede ser necesario realizar ensayos de medicación empírica, intervenciones conductuales y pruebas objetivas de laringovideostroboscopia, reflujo basado en impedancia y motilidad esofágica, a veces de manera experimental, para diagnosticar y tratar correctamente los síntomas de un paciente.

The Use of FTIR Spectroscopy as a Tool for the Seasonal Variation Analysis and for the Quality Control of Polysaccharides from Seaweeds.

Macroalgae are a potentially novel source of nutrition and biologically active molecules. Proliferative species such as Eucheuma denticulatum, Solieria chordalis (red algae) and Sargassum muticum (brown alga) constitute a huge biomass that can be exploited. In this study, we focus on the extraction of polysaccharides from these three macroalgae species and the characterization of cell wall polysaccharides such as carrageenans, fucoidans and alginates by Fourier Transform Infrared spectroscopy with Attenuated Reflectance Module (FTIR-ATR). The comparison of purified extracts with commercial solutions of fucoidans, alginates or carrageenans shows a strong similarity between the spectra. It demonstrates that the methods of extraction that have been used are also suitable purifying technics. Moreover, it validates infrared spectroscopy as a quick, simple and non-destructive method for the accurate analysis of polysaccharides. The FTIR technique applied to samples collected at different periods of the year allowed us to highlight differences in the composition of fucoidans, alginates and carrageenans. Different classes corresponding to the season can be distinguished by statistical multidimensionnal analysis (Principal Component Analysis) showing that the structure of algal polysaccharides, related to bioactivity, depends on the period of harvest. FTIR results showed that S. chordalis and E. denticulatum possess a dominant type of carrageenan called iota-carrageenan. This type of carrageenan is in the majority when the alga is at maturity in its development cycle. During its growth phase, iota-carrageenan precursors can be detected by FTIR spectra, enabling a better control of the extraction and an application of these compounds in various economic sectors. When the alga E. denticulatum is in its juvenile stage, we found traces of kappa-carrageenan and nu-carrageenan polysaccharides in some extracts.

Alginate-metal cation interactions: Macromolecular approach.

Alginates are a broad family of linear (unbranched) polysaccharides derived from brown seaweeds and some bacteria. Despite having only two monomers, i.e. ß-d-mannuronate (M) and its C5 epimer α-l-guluronate (G), their blockwise arrangement in oligomannuronate (..MMM..), oligoguluronate (..GGG..), and polyalternating (..MGMG..) blocks endows it with a rather complex interaction pattern with specific counterions and salts. Classic polyelectrolyte theories well apply to alginate as polyanion in the interaction with monovalent and non-gelling divalent cations. The use of divalent gelling ions, such as Ca2+, Ba2+ or Sr2+, provides thermostable homogeneous or heterogeneous hydrogels where the block composition affects both macroscopic and microscopic properties. The mechanism of alginate gelation is still explained in terms of the original egg-box model, although over the years some novel insights have been proposed. In this review we summarize several decades of research related to structure-functionships in alginates in the presence of non-gelling and gelling cations and present some novel applications in the field of self-assembling nanoparticles and use of radionuclides.

Polysaccharides from the Sargassum and Brown Algae Genus: Extraction, Purification, and Their Potential Therapeutic Applications.

Brown macroalgae represent one of the most proliferative groups of living organisms in aquatic environments. Due to their abundance, they often cause problems in aquatic and terrestrial ecosystems, resulting in health problems in humans and the death of various aquatic species. To resolve this, the application of Sargassum has been sought in different research areas, such as food, pharmaceuticals, and cosmetics, since Sargassum is an easy target for study and simple to obtain. In addition, its high content of biocompounds, such as polysaccharides, phenols, and amino acids, among others, has attracted attention. One of the valuable components of brown macroalgae is their polysaccharides, which present interesting bioactivities, such as antiviral, antimicrobial, and antitumoral, among others. There is a wide variety of methods of extraction currently used to obtain these polysaccharides, such as supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), subcritical water extraction (SCWE), ultrasound-assisted extraction (UAE), enzyme-assisted extraction (EAE), and microwave-assisted extraction (MAE). Therefore, this work covers the most current information on the methods of extraction, as well as the purification used to obtain a polysaccharide from Sargassum that is able to be utilized as alginates, fucoidans, and laminarins. In addition, a compilation of bioactivities involving brown algae polysaccharides in in vivo and in vitro studies is also presented, along with challenges in the research and marketing of Sargassum-based products that are commercially available.

Recent update on alginate based promising transdermal drug delivery systems.

Alongside oral delivery of therapeutics, transdermal delivery systems have gained increased patient acceptability over past few decades. With increasing popularity, novel techniques were employed for transdermal drug targeting which involves microneedle patches, transdermal films and hydrogel based formulations. Hydrogel forming ability along with other rheological behaviour makes natural polysaccharides an attractive option for transdermal use. Being a marine originated anionic polysaccharide, alginates are widely used in pharmaceutical, cosmetics and food industries. Alginate possesses excellent biodegradability, biocompatibility and mucoadhesive properties. Owing to many favourable properties required for transdermal drug delivery systems (TDDS), the application of alginates are increasing in recent times. This review summarizes the source and properties of alginate along with several transdermal delivery techniques including the application of alginate for respective transdermal systems.

Spatially resolved polymer mobilization revisited - Three-dimensional, UltraShort Echo Time (3D UTE) magnetic resonance imaging of sodium alginate matrix tablets.

HYPOTHESIS: Three-dimensional 1H UltraShort Echo Time magnetic resonance imaging (1H 3D UTE MRI) of the matrix tablet made of hydrophilic polymer hydrated in heavy water (D2O) will allow investigation of the hydration-induced spatiotemporal evolution of the material originally included in the matrix tablet during manufacturing (i.e., polymer chains and bound water). EXPERIMENTS: The oblong-shaped sodium alginate matrix tablets were used to verify the hypothesis. The matrix was measured before and during hydration in D2O for up to 2 h using the 1H 3D UTE MRI. Five echo times (first at 20 µs) were used, resulting in five three-dimensional images (one image for each echo time). In chosen cross-sections, two parametric images, i.e., amplitude and T2* relaxation time maps, were calculated using "pixel-by-pixel" mono-exponential fitting. FINDINGS: The regions of the alginate matrix with T2* shorter than 600 µs were analyzed before (air-dry matrix) and during hydration (parametric, spatiotemporal analysis). During the study, only hydrogen nuclei (protons) pre-existing in the air-dry sample (polymer and bound water) were monitored because the hydration medium (D2O) was not visible. As a result, it was found that morphological changes in regions having T2* shorter than 300 µs were the effect of fast initial water ingress into the core of the matrix and subsequent polymer mobilization (early hydration providing additional 5% w/w hydration medium content relating to air-dry matrix). In particular, evolving layers in T2* maps were detected, and a fracture network was formed shortly after the matrix immersion in D2O. The current study presented a coherent picture of polymer mobilization accompanied by local polymer density decrease. We concluded, that the T2* mapping using 3D UTE MRI can effectively be applied as a polymer mobilization marker.