Exploring the Drug-Loading and Release Ability of FucoPol Hydrogel Membranes.

The polysaccharide FucoPol has recently been shown to yield hydrogel membranes (HMs) characterized by good mechanical properties, biocompatibility, and anti-inflammatory activity that render them promising biomaterials for use in the biomedical field. Subsequently to such findings, envisaging their development into novel delivery systems for topical applications, in this study, FucoPol HMs prepared by crosslinking the biopolymer with iron cations were loaded with caffeine or diclofenac sodium as model drugs. Two loading methods, namely diffusion and mixing, were applied to evaluate the FucoPol's HM drug-loading capacity and entrapment efficiency. The diffusion method led to a higher caffeine loading (101.9 ± 19.1 mg/g) in the HM1_DCAF membranes, while the mixing method resulted in a higher diclofenac sodium loading (82.3 ± 5.1 mg/g) in the HM1_DDS membranes. The HM1_DCAF membranes were characterized by increased mechanical and rheological parameters, such as their hardness (130.0 ± 5.3 kPa) and storage modulus (1014.9 ± 109.7 Pa), compared to the HM1_DDS membranes that exhibited lower values (7.3 ± 1.2 kPa and 19.8 ± 3.8 Pa, respectively), probably due to leaching occurring during the drug-loading process. The release profiles revealed a fast release of both APIs from the membranes loaded by diffusion, while a prolonged and sustained release was obtained from the membranes loaded by mixing. Moreover, for all API-loaded membranes, the release mechanism followed Fickian diffusion, with the release rate being essentially governed by the diffusion process. These findings, together with their previously shown biological properties, support the suitability of the developed FucoPol HMs to be used as platforms for the topical delivery of drugs.

Adipose Tissue Dysfunction: Impact on Metabolic Changes?

Adipose tissue is a metabolically dynamic organ that is the primary site of storage for excess energy, but it serves as an endocrine organ capable of synthesizing a number of biologically active compounds that regulate metabolic homeostasis. However, when the capacity of expansion of this tissue exceeds, dysfunction occurs, favoring ectopic accumulation of fat in the visceral, which has been implicated in several disease states, most notably obesity. This review highlights the mechanisms involved in the structure of adipose tissue, tissue expandability, adipocyte dysfunction, as well as the impact of these events on the manifestation of important metabolic disorders associated with adipose tissue dysfunction. A literature search using Pubmed, Web of Science, Scopus, and Cochrane databases were used to identify relevant studies, using clinical trials, experimental studies in animals and humans, case-control studies, case series, letters to the editor, and review articles published in English, without restrictions on year of publication. The excessive ectopic lipid accumulation leads to local inflammation and insulin resistance. Indeed, overnutrition triggers uncontrolled inflammatory responses white adipose tissue, leading to chronic low-grade inflammation, therefore fostering the progression of important metabolic disorders. Thus, it is essential to advance the understanding of the molecular mechanisms involved in adipose tissue dysfunction in order to mitigate the negative metabolic consequences of obesity.

Repurposed Drugs in Gastric Cancer.

Gastric cancer (GC) is one of the major causes of death worldwide, ranking as the fifth most incident cancer in 2020 and the fourth leading cause of cancer mortality. The majority of GC patients are in an advanced stage at the time of diagnosis, presenting a poor prognosis and outcome. Current GC treatment approaches involve endoscopic detection, gastrectomy and chemotherapy or chemoradiotherapy in an adjuvant or neoadjuvant setting. Drug development approaches demand extreme effort to identify molecular mechanisms of action of new drug candidates. Drug repurposing is based on the research of new therapeutic indications of drugs approved for other pathologies. In this review, we explore GC and the different drugs repurposed for this disease.

Deacetylation and Desuccinylation of the Fucose-Rich Polysaccharide Fucopol: Impact on Biopolymer Physical and Chemical Properties.

FucoPol is an acylated polysaccharide with demonstrated valuable functional properties that include a shear thinning fluid behaviour, a film-forming capacity, and an emulsion forming and stabilizing capacity. In this study, the different conditions (concentration, temperature, and time) for alkaline treatment were investigated to deacylate FucoPol. Complete deacetylation and desuccinylation was achieved with 0.02 M NaOH, at 60 °C for 15 min, with no significant impact on the biopolymer's sugar composition, pyruvate content, and molecular mass distribution. FucoPol depyruvylation by acid hydrolysis was attempted, but it resulted in a very low polymer recovery. The effect of the ionic strength, pH, and temperature on the deacetylated/desuccinylated polysaccharide, d-FucoPol, was evaluated, as well as its emulsion and film-forming capacity. d-FucoPol aqueous solutions maintained the shear thinning behaviour characteristic of FucoPol, but the apparent viscosity decreased significantly. Moreover, contrary to FucoPol, whose solutions were not affected by the media's ionic strength, the d-FucoPol solutions had a significantly higher apparent viscosity for a higher ionic strength. On the other hand, the d-FucoPol solutions were not affected by the pH in the range of 3.6-11.5, while FucoPol had a decreased viscosity for acidic pH values and for a pH above 10.5. Although d-FucoPol displayed an emulsification activity for olive oil similar to that of FucoPol (98 ± 0%) for an oil-to-water ratio of 2:3, the emulsions were less viscous. The d-FucoPol films were flexible, with a higher Young's modulus (798 ± 152 MPa), a stress at the break (22.5 ± 2.5 MPa), and an elongation at the break (9.3 ± 0.7%) than FucoPol (458 ± 32 MPa, 15.5 ± 0.3 MPa and 8.1 ± 1.0%, respectively). Given these findings, d-FucoPol arises as a promising novel biopolymer, with distinctive properties that may render it useful for utilization as a suspending or emulsifier agent, and as a barrier in coatings and packaging films.

Intervention Programs Targeting Burnout in Health Professionals: A Systematic Review.

Background: Burnout is an occupational syndrome, with a higher prevalence in professionals whose close involvement with other people is significant. There is a great diversity of professionals at risk of burnout, and therefore the implementation of intervention programs is relevant, as helping people to maintain their mental and emotional health enables them to become more meaningfully involved in their communities and become more effective and active global citizens. We aimed to review systematically the characteristics of interventions targeting burnout in health professionals. Methods: The search was conducted in three databases: Scopus, Web of Science, and PubMed, following the PRISMA model, and 16 eligible articles were identified between 2012 and 2023. Results: Mindfulness showed great efficacy in preventing burnout, by reducing stress levels and promoting empathy. In addition, relaxation and breathing techniques, yoga, and music therapy showed to improve burnout and occupational stress levels. Balint groups have also helped slow the progression of burnout. Implications about the need for future research to foster the promotion of well-being and mental health of health professionals are mentioned. Conclusion: Mindfulness, relaxation and breathing techniques, yoga, music therapy and balint groups proved to be effective in preventing burnout.

Iron(III) cross-linked hydrogels based on Alteromonas macleodii Mo 169 exopolysaccharide.

Recently, polysaccharide-based hydrogels crosslinked with the trivalent iron cation have attracted interest due to their remarkable properties that include high mechanical stability, stimuli-responsiveness, and enhanced absorptivity. In this study, a Fe3+ crosslinked hydrogel was prepared using the biocompatible extracellular polysaccharide (EPS) secreted by the marine bacterium Alteromonas macleodii Mo169. Hydrogels with mechanical strengths (G') ranging from 0.3 kPa to 44.5 kPa were obtained as a result of the combination of different Fe3+ (0.05-9.95 g L-1) and EPS (0.3-1.7 %) concentrations. All the hydrogels had a water content above 98 %. Three different hydrogels, named HA, HB, and HC, were chosen for further characterization. With strength values (G') of 3.2, 28.9, and 44.5 kPa, respectively, these hydrogels might meet the strength requirements for several specific applications. Their mechanical resistance increased as higher Fe3+ and polymer concentrations were used in their preparation (the compressive hardness increased from 8.7 to 192.1 kPa for hydrogel HA and HC, respectively). In addition, a tighter mesh was noticed for HC, which was correlated to its lower swelling ratio value compared to HA and HB. Overall, this preliminary study highlighted the potential of these hydrogels for tissue engineering, drug delivery, or wound healing applications.

Effect of whitening dentifrices on dental enamel: an analysis of color, microhardness, and surface roughness in vitro.

OBJECTIVES: This study aimed to evaluate the influence of different whitening toothpastes on color change and alteration in enamel surface roughness and microhardness compared to a conventional toothpaste. METHOD AND MATERIALS: Fifty bovine incisors were selected, cleaned, and stored before being divided into five groups: a conventional toothpaste group and three whitening toothpaste groups containing different abrasive agents: silica, hydrogen peroxide, and activated charcoal. Specimens underwent simulated brushing, staining with black tea solution, and subsequent analyses of color, surface roughness, and microhardness. Statistical analysis was performed using three-way ANOVA and Tukey post-hoc tests (P .05). RESULTS: The results showed that the color analysis revealed similar whitening potential among all toothpastes. They showed significant differences in surface roughness (P .001) and microhardness (P .001) after simulated brushing. While all toothpastes caused a decrease in microhardness, the charcoal-based toothpaste showed a significant increase in surface roughness compared to the initial condition. CONCLUSION: All toothpastes demonstrated whitening capability. Surface roughness changed after brushing with activated charcoal-based whitening toothpaste, but final roughness was similar across all groups. Whitening toothpastes led to a decrease in enamel microhardness, with similar final performance across all toothpastes analyzed.

Chitin-Glucan Complex Hydrogels: Physical-Chemical Characterization, Stability, In Vitro Drug Permeation, and Biological Assessment in Primary Cells.

Chitin-glucan complex (CGC) hydrogels were fabricated by coagulation of the biopolymer from an aqueous alkaline solution, and their morphology, swelling behavior, mechanical, rheological, and biological properties were studied. In addition, their in vitro drug loading/release ability and permeation through mimic-skin artificial membranes (Strat-M) were assessed. The CGC hydrogels prepared from 4 and 6 wt% CGC suspensions (Na51*4 and Na51*6 hydrogels, respectively) had polymer contents of 2.40 ± 0.15 and 3.09 ± 0.22 wt%, respectively, and displayed a highly porous microstructure, characterized by compressive moduli of 39.36 and 47.30 kPa and storage moduli of 523.20 and 7012.25 Pa, respectively. Both hydrogels had a spontaneous and almost immediate swelling in aqueous media, and a high-water retention capacity (>80%), after 30 min incubation at 37 °C. Nevertheless, the Na51*4 hydrogels had higher fatigue resistance and slightly higher-water retention capacity. These hydrogels were loaded with caffeine, ibuprofen, diclofenac, or salicylic acid, reaching entrapment efficiency values ranging between 13.11 ± 0.49% for caffeine, and 15.15 ± 1.54% for salicylic acid. Similar release profiles in PBS were observed for all tested APIs, comprising an initial fast release followed by a steady slower release. In vitro permeation experiments through Strat-M membranes using Franz diffusion cells showed considerably higher permeation fluxes for caffeine (33.09 µg/cm2/h) and salicylic acid (19.53 µg/cm2/h), compared to ibuprofen sodium and diclofenac sodium (4.26 and 0.44 µg/cm2/h, respectively). Analysis in normal human dermal fibroblasts revealed that CGC hydrogels have no major effects on the viability, migration ability, and morphology of the cells. Given their demonstrated features, CGC hydrogels are very promising structures, displaying tunable physical properties, which support their future development into novel transdermal drug delivery platforms.

Novel Hydrogel Membranes Based on the Bacterial Polysaccharide FucoPol: Design, Characterization and Biological Properties.

FucoPol, a fucose-rich polyanionic polysaccharide, was used for the first time for the preparation of hydrogel membranes (HMs) using Fe3+ as a crosslinking agent. This study evaluated the impact of Fe3+ and FucoPol concentrations on the HMs' strength. The results show that, above 1.5 g/L, Fe3+ concentration had a limited influence on the HMs' strength, and varying the FucoPol concentration had a more significant effect. Three different FucoPol concentrations (1.0, 1.75 and 2.5 wt.%) were combined with Fe3+ (1.5 g/L), resulting in HMs with a water content above 97 wt.% and an Fe3+ content up to 0.16 wt.%. HMs with lower FucoPol content exhibited a denser porous microstructure as the polymer concentration increased. Moreover, the low polymer content HM presented the highest swelling ratio (22.3 ± 1.8 g/g) and a lower hardness value (32.4 ± 5.8 kPa). However, improved mechanical properties (221.9 ± 10.2 kPa) along with a decrease in the swelling ratio (11.9 ± 1.6 g/g) were obtained for HMs with a higher polymer content. Furthermore, all HMs were non-cytotoxic and revealed anti-inflammatory activity. The incorporation of FucoPol as a structuring agent and bioactive ingredient in the development of HMs opens up new possibilities for its use in tissue engineering, drug delivery and wound care management.

Repurposing Benztropine, Natamycin, and Nitazoxanide Using Drug Combination and Characterization of Gastric Cancer Cell Lines.

Gastric cancer (GC) ranked as the fifth most incident cancer in 2020 and the third leading cause of cancer mortality. Surgical prevention and radio/chemotherapy are the main approaches used in GC treatment, and there is an urgent need to explore and discover innovative and effective drugs to better treat this disease. A new strategy arises with the use of repurposed drugs. Drug repurposing coupled with drug combination schemes has been gaining interest in the scientific community. The main objective of this project was to evaluate the therapeutic effects of alternative drugs in GC. For that, three GC cell lines (AGS, MKN28, and MKN45) were used and characterized. Cell viability assays were performed with the reference drug 5-fluororacil (5-FU) and three repurposed drugs: natamycin, nitazoxanide, and benztropine. Nitazoxanide displayed the best results, being active in all GC cells. Further, 5-FU and nitazoxanide in combination were tested in MKN28 GC cells, and the results obtained showed that nitazoxanide alone was the most promising drug for GC therapy. This work demonstrated that the repurposing of drugs as single agents has the ability to decrease GC cell viability in a concentration-dependent manner.

Chitin-Glucan Complex Hydrogels: Optimization of Gel Formation and Demonstration of Drug Loading and Release Ability.

Chitin-glucan complex (CGC) hydrogels were fabricated through a freeze-thaw procedure for biopolymer dissolution in NaOH 5 mol/L, followed by a dialysis step to promote gelation. Compared to a previously reported methodology that included four freeze-thaw cycles, reducing the number of cycles to one had no significant impact on the hydrogels' formation, as well as reducing the total freezing time from 48 to 18 h. The optimized CGC hydrogels exhibited a high and nearly spontaneous swelling ratio (2528 ± 68%) and a water retention capacity of 55 ± 3%, after 2 h incubation in water, at 37 °C. Upon loading with caffeine as a model drug, an enhancement of the mechanical and rheological properties of the hydrogels was achieved. In particular, the compressive modulus was improved from 23.0 ± 0.89 to 120.0 ± 61.64 kPa and the storage modulus increased from 149.9 ± 9.8 to 315.0 ± 76.7 kPa. Although the release profile of caffeine was similar in PBS and NaCl 0.9% solutions, the release rate was influenced by the solutions' pH and ionic strength, being faster in the NaCl solution. These results highlight the potential of CGC based hydrogels as promising structures to be used as drug delivery devices in biomedical applications.

Canine Gastric Cancer: Current Treatment Approaches.

Human gastric cancer (GC) ranks as the fifth most prevalent cancer worldwide, and is the third leading cause of cancer-related death. The incidence of GC is lower in dogs than in humans, accounting for less than 1% of all canine malignancies. In recent years, efforts have been made to understand the pathogenesis of GC and in find an appropriate therapy to maximize curative results, such as adjuvant chemotherapy treatments in addition to surgery. Although surgery is the first-line treatment, it is associated with several complications. In terms of chemotherapeutic intervention, canine gastric cancer has not received much attention, probably due to its late diagnosis, fast progression, low median survival time, and very high mortality rate, along with the lack of publications with concrete scientific results. In this review, we explore canine GC and the pharmacological approach used in the treatment of this often-fatal disease.

Nutritional status of selenium in overweight and obesity: A systematic review and meta-analysis.

BACKGROUND & AIMS: Selenium is an antioxidant and anti-inflammatory nutrient and regulates important physiological processes, such as carbohydrate and lipid metabolism, immune system actions, and adipocyte differentiation. Given these important functions, several studies have assessed the nutritional status of selenium to elucidate whether its homeostasis is impaired by excess adiposity, which in turn could contribute to the adipose tissue dysfunction and metabolic disorders. However, the results of these studies are quite controversial. Therefore, this systematic review and meta-analysis aimed to assess differences in the nutritional status of selenium in overweight/obese individuals. METHODS: We searched the PubMed, Scopus, Web of Science, Embase, Cochrane Library, and Virtual Health Library databases. Studies comparing overweight or obese individuals with eutrophic individuals and assessing at least one marker of selenium were included. Comprehensive Meta-Analysis software was used to perform meta-analysis. The effect size was calculated using the raw mean difference or the standardized mean difference, with 95% confidence interval and a p-value of <0.05. Heterogeneity was determined using the I2 index. Subgroup analyses were performed according to sex, body mass index (BMI), and selenium content in the soil. The protocol of this review was registered in the Prospective Register of Systematic Reviews (registration number: CRD42020185405). RESULTS: This systematic review included 73 articles, of which 65 articles were eligible for meta-analysis. There were no significant differences between the overweight/obesity and eutrophy groups in terms of dietary intake and plasma/serum levels of selenium and selenoprotein P levels. The activity of plasma/serum glutathione peroxidase was decreased in the overweight/obese children and adolescents; however, the difference was no statistically significant when the enzyme activity was analyzed in erythrocytes and whole blood. In the adult age group, overweight/obese individuals had decreased activity of both glutathione peroxidase isoforms compared to those individuals with eutrophy. In particular, the activity of erythrocyte glutathione peroxidase was significantly decreased in obese individuals and those living in regions with low-to-moderate selenium content in the soil. Regarding selenium excretion markers, overweight/obese individuals had lower levels of selenium in the urine and nails and a trend of higher levels of selenium in the hair than eutrophic individuals. CONCLUSIONS: In conditions of excess adiposity, the main alteration in the nutritional status of selenium is a decrease in glutathione peroxidase activity, particularly in adults with obesity. In addition, reduced levels of selenium in urine and nails can be found in overweight or obese individuals.

Characterization of Suspected Crimes against Companion Animals in Portugal.

Animal crimes are a widespread phenomenon with serious implications for animal welfare, individual well-being and for society in general. These crimes are universal and represent a major problem in human/animal interaction. In Portugal, current law 69/2014 criminalizes the mistreatment and abandonment of companion animals. This study characterizes forensic cases received at the Laboratory of Pathology of the National Institute of Agrarian and Veterinary Investigation (Vairão) since the enforcement of the aforementioned legislation. A retrospective study was carried out based on the consult of 160 data files of forensic necropsies from 127 dogs and 33 cats. Necropsies confirmed prior crime suspicion in 38 cases (24%), from which 33 were dogs and five were cats. Among confirmed cases, most of assaulted animals were medium-size (57%), crossbreed (55%) male (58%) dogs (87%), which were the victims of blunt force trauma (31%), firearms (27%), poisoning (27%) and asphyxiation (15%). In cats, most of the assaulted animals were juvenile (60%) females (60%) of unknown breed (40%), which suffered blunt force trauma (100%) as the only cause of death. The present study shows that violence against animals is a reality, and complaints about these crimes are gradually increasing due to the population's raising awareness about animal rights. Greater communication and coordination between clinicians, veterinary pathologists, and law enforcement officers are essential to validate and legally support these cases and subject them to trial.

A comprehensive review of the antibacterial activity of dimethylaminohexadecyl methacrylate (DMAHDM) and its influence on mechanical properties of resin-based dental materials.

The repetitive restorative cycle should be avoided, aiming at the smallest number of restorations' replacements to ensure greater tooth longevity. Antibacterial materials associated with the control of caries etiological factors can help improve restoration's durability. This review aimed to analyze the results of in vitro studies that added Dimethylaminohexadecyl methacrylate (DMAHDM), an antibacterial monomer, to restorative materials. The PubMed, SCOPUS, Web of Science, and Biblioteca Virtual em Saúde databases were screened for studies published between 2015 and 2020. After full-text reading, 24 articles were included in the final sample. DMAHDM has demonstrated antibacterial efficacy against several bacteria related to dental caries and periodontal diseases, causing a transition in the biofilm balance without inducing resistance. When DMAHDM was included in acrylic resin, the material cytotoxicity increased, and changes in mechanical properties were observed. In contrast, resin composites had their mechanical properties maintained in most studies; however, toxicity was not examined. The association between DMAHDM and 2-methacryloyloxyethyl phosphorylcholine or silver nanoparticles improved the antibacterial effect. Besides, the association with nanoparticles of amorphous calcium phosphate or nanoparticles of calcium fluoride can provide remineralization capacity. There is a lack of information on the cytotoxicity and bacteria resistance induction, and further studies are needed to address this.

Production of medium-chain-length polyhydroxyalkanoates by Pseudomonas chlororaphis subsp. aurantiaca: Cultivation on fruit pulp waste and polymer characterization.

Pseudomonas chlororaphis subsp. aurantiaca DSM 19603 was cultivated on apple pulp, a glucose- and fructose-rich waste generated during juice production, to produce medium-chain length polyhydroxyalkanoates. A cell dry mass of 8.74 ± 0.20 g/L, with a polymer content of 49.25 ± 4.08% were attained. The produced biopolymer was composed of 42.7 ± 0.1 mol% 3-hydroxydecanoate, 17.9 ± 1.0 mol% 3-hydroxyoctanoate, 14.5 ± 1.1 mol% 3-hydroxybutyrate, 11.1 ± 0.6 mol% 3-hydroxytetradecanoate, 10.1 ± 0.5 mol% 3-hydroxydodecanoate and 3.7 ± 0.2 mol% 3-hydroxyhexanoate. It presented low glass transition and melting temperatures (-40.9 ± 0.7 °C and 42.0 ± 0.1 °C, respectively), and a degradation temperature of 300.0 ± 0.1 °C, coupled to a low crystallinity index (12.7 ± 2.7%), a molecular weight (Mw) of 1.34 × 105 ± 0.18 × 105 Da and a polydispersity index of 2.70 ± 0.03. The biopolymer's films were dense and had a smooth surface, as demonstrated by Scanning Electron Microscopy. They presented a tension at break of 5.21 ± 1.09 MPa, together with an elongation of 400.5 ± 55.8% and an associated Young modulus of 4.86 ± 1.49 MPa, under tensile tests. These attractive filming properties of this biopolymer could potentially be valorised in several areas such as the fine chemicals industry, biomedicine, pharmaceuticals, or food packaging.

Novel hydrogels based on yeast chitin-glucan complex: Characterization and safety assessment.

Chitin-glucan complex (CGC) was used for the first time for the preparation of hydrogels. Alkali solvent systems, NaOH and KOH solutions, either at 1 or 5 mol/L, were used for CGC dissolution using a freeze-thaw procedure (freezing at -20 °C and thawing at room temperature; four cycles). The CGC solutions thus obtained were subjected to dialysis that induced the spontaneous gelation of the biopolymer, yielding translucid hydrogels with a yellowish coloration. Although all CGC hydrogels exhibited porous microstructures, high water content (above 97%) and good mechanical properties, their morphology, viscoelastic properties and texture were influenced by the type of solvent system used for CGC dissolution, as well as by their ionic strength. The K-based hydrogels presented a less compact network with larger pores and exhibited lower elastic properties. The Na-based hydrogels, on the other hand, exhibited a denser structure with smaller pores and a stiffer gel structure. These results show that it is possible to prepare CGC hydrogels with differing characteristics that can be suitable for different applications. Furthermore, all hydrogels were non-cytotoxic towards L929 fibroblasts and HaCaT keratinocytes. This study demonstrates CGC can be used to prepare biocompatible hydrogels with properties render them promising biomaterials.

Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer.

Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63-68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9-50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials.

Microneedle Arrays of Polyhydroxyalkanoate by Laser-Based Micromolding Technique.

Although many delivery systems have been proposed to improve drug permeation through the skin, all of them suffer from several limitations. This drives a continuous search for innovative systems that can provide safe and effective transdermal drug delivery solutions. In line with this, microneedle (MN) arrays, a hybrid combination of hypodermic injections and transdermal patches, have been proposed. MNs consist of microscale needles that can pierce the skin by a simple, minimally invasive, and painless route, enabling the transport of drugs and macromolecules into the human body. This study reports, for the first time, the use of a biobased, biodegradable, and biocompatible polymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), for the fabrication of a biopolymer-based MN patch. Molds of poly(dimethylsiloxane) were prepared by direct laser writing technology, a low-cost and mask-less technology, and used to produce biodegradable P(3HB-co-3HV) MNs by a thermosetting process. The best results were obtained with a laser power of 30 W at 0.15 m/s with a spiral model as the pattern. The obtained MNs had a length of 0.69 mm and a diameter of 0.33 mm, ideal for painless penetration of the skin. Additionally, the produced MNs had good mechanical properties and the ability to be successfully impregnated with the fluorescent dye Rhodamine 6G. These features render P(3HB-co-3HV) a promising material for the development of MNs with improved functionality.

Chitin-glucan complex - Based biopolymeric structures using biocompatible ionic liquids.

This work explores the novelty of dissolving chitin-glucan complex (CGC), from two fungal strains, Komagataella pastoris (CGCP) and Aspergillus niger (CGCKZ) (KiOnutrime-CG™), using biocompatible ionic liquids (ILs). Three cholinium-based ILs were tested, choline acetate, choline propionate and choline hexanoate. Although all tested ILs resulted in the dissolution of the co-polymer at a concentration of 5 % (w/w), distinct polymeric structures, films or gels, were obtained from CGCP and CGCKZ, respectively. CGCP films were dense, flexible and elastic, with high swelling capacity (> 200 %). The IL anion alkyl chain length influenced the polymeric structures' properties, namely, the CGCP films elongation at break and swelling degree. CGCKZ resulted in weak gels. For both polymeric structures, exposure to the ILs under the dissolution conditions caused significant changes in the co-polymers' chemical structure, namely, reduction of their glucan moiety and reduction of the degree of acetylation, thus yielding chitosan-glucan complexes (ChGC) enriched in glucosamine (53.4 ± 0.3-60.8 ± 0.3 %).