Hydrogels have been used as matrices for the topical delivery of nitric oxide (NO) for achieving vasodilation, wound healing and analgesic actions. More recently, supramolecular hydrogels comprised ...of poly(acrylic acid) (PAA) and micellar Pluronic F127 (F127), prepared by thermal reaction, emerged as a suitable matrix for the incorporation of hydrophilic NO donors, such as
S
-nitrosoglutathione (GSNO). Herein, we describe an innovative method for the three-dimensional (3D) printing of cellulose nanocrystal (CNC)-containing and semi-interpenetrating PAA/F127 hydrogels by PAA photopolymerization
via
digital light processing (DLP), in the absence of organic solvents. Scanning electron microscopy showed that, differently from typical porous PAA-based hydrogels, the 3D printed PAA/F127/CNC hydrogels have dense morphology. By using transmission electron microscopy we confirmed for the first time the presence of F127 micelles in the printable resin, and their preservation after the photopolymerization process. The F127 micelles conferred compressive recoverability to the 3D printed PAA/F127/CNC hydrogels, widening their potential applications as soft biomaterials. PAA/F127/CNC hydrogels charged with GSNO are shown to release NO spontaneously upon hydration at initial rates that depend on the GSNO charge and are higher in the presence of CNC. As local NO release may exert cell proliferation action, 3D printed PAA/F127/CNC/GSNO hydrogels may serve as a versatile soft biomaterial for local NO delivery in regenerative medicine and other biomedical applications.
3D printed semi-IPN hydrogels of poly(acrylic acid), micellar Pluronic F127 and cellulose nanocrystals containing S-nitrosoglutathione are flexible and capable of releasing nitric oxide.
Many of the drugs used to fight cancer cells induce various damage causing hepatotoxic effects which are characterized by tissue changes. The aim of the study is to know the possible effects of ...salazinic acid on livers of mice exposed to Sacoma-180. The tumor was grown in the animals in ascitic form and inoculated subcutaneously in the axillary region of the mouse developing the solid tumor. Treatment with salazinic acid (25 and 50 mg/kg) and 5-Fluorouracil (20 mg/kg) started 24-hours after inoculation and was performed for 7 days. To verify these effects, the qualitative method of histological criteria investigated in liver tissue was used. It was observed that all treated groups showed an increase of pyknotic nuclei in relation to the negative control. There was an increase in steatosis in all groups compared to the negative control but there was a decrease in the groups treated with salazinic acid in the 5-Fluorouracil. There was no necrosis in the salazinic acid treated groups. However, this effect was seen in 20% of the positive control group. Therefore, it can be concluded that salazinic acid did not show hepatoprotective action on mice but demonstrated a decrease in steatosis and absence of tissue necrosis.
Abstract Studies evaluating the structure and diversity of bacterial communities in arid environments including the rhizosphere of local and adapted plant species are important. Therefore, we used a ...sequencing of the 16S ribosomal RNA gene for describing the structure and diversity of soil bacterial community in three zones: Agreste, Transition and Sertão. The bacterial community was clustered in 9,838 OTUs in Agreste, 8,388 OTUs in the transition, and 14,849 OTUs for Sertão. Among the most abundant phyla, Proteobacteria and Acidobacteria were abundant in Agreste and Sertão, respectively, while Actinobacteria were abundant in Transition and Sertão. Specific taxa of Proteobacteria, in Agreste, and Actinobacteria, in Sertão, exhibited differences according to biotic and abiotic conditions. Thus, the structure and diversity of bacterial community were different in these areas and were influenced by environmental and soil conditions.
Cellulose nanocrystal (CNC) incorporation in polymeric matrices is an environmentally friendly approach to mechanical reinforcement. In general, significant mechanical reinforcement can only be ...achieved by means of good CNC dispersion at random orientation. These primary characteristics are even more relevant for the preparation of nanocomposites based on hydrophobic matrices, such as poly(ε-caprolactone) (PCL). A straightforward approach to improve CNC dispersion in hydrophobic matrices is their surface modification. However, this extra step is usually complex and often impairs particle–particle interactions, which are also key to mechanical reinforcement. In this work, poly(ε-caprolactone)/neat cellulose nanocrystal nanocomposites were prepared by a specific procedure that combined solvent exchange and solvent casting methodologies, avoiding the use of any additives or chemical modification. These nanocomposites were investigated in terms of the CNC percolation network formation and its effect on the overall mechanical properties. The results showed that significant mechanical reinforcement was obtained, reaching a 155% Young’s modulus increase at 25 wt% CNC content. TEM showed a percolated network in the PCL/CNC25 nanocomposite. In terms of morphology and nanostructure, increasing CNC concentration also promoted a reduction in PCL spherulite size and lamellar thickness. These results pointed out to CNC preferential localization in the interfibrillar region. In conclusion, the solvent exchange methodology presented herein led to mechanically reinforced PCL/CNC nanocomposites with small crystalline domains intertwined with a percolated CNC network.
Cellulose nanocrystals (CNC)‐based foams are promising tissue engineering materials that may facilitate implant‐tissue integration and allow localized and controlled drug delivery. Herein, hybrid ...CNC‐based foams, which are ultralightweight (30–100 mg cm−3), highly porous (>95%), ominiphilic and superabsorbent (1500–3000 wt% of water and/or toluene uptake) are obtained by the in situ condensation of poly(ethylene glycol) ditriethoxysilyl (TES‐PEG‐TES) into a 3D network, where silsesquioxane nanoparticles (SS‐NP) are the crosslinking nodes, and CNC are entrapped forming ionic interactions, in a supramolecular structure. In a new approach, using 3‐mercaptopropyltrimethoxysilane, sulfhydryl groups are inserted on the SS‐NP periphery and S‐nitrosated to enable the functionalization of SS‐NP with S‐nitrosothiol groups, which can nitric oxide (NO), in a process triggered by the hydration of the foams and modulated by their supramolecular structure. CNC‐SS‐PEG foams exhibit elevated thermal and structural stability, compressive strength compatible with various soft human tissues, and NO release rates (1–18 pmol mg−1 min−1) within the range of the beneficial NO actions. Thus, the CNC‐SS‐PEG foams herein described represent a new platform of supramolecular hybrid materials for localized delivery of NO, with potential uses in tissue engineering and other biomedical applications.
Supramolecular cellulose nanocrystal‐based foams are produced by the in situ condensation of poly(ethylene glycol)ditriethoxysilyl, generating a 3D hybrid network. Sulfhydryl groups at the periphery of silsesquioxane nanoparticles are S‐nitrosated to release nitric oxide spontaneously upon hydration with rates controlled by the supramolecular structure. Foams show potential application as platforms for localized nitric oxide delivery.
Despite success in achieving viral suppression during pregnancy in people living with HIV (PLWH), postpartum adherence remains a challenge. We aimed to describe rates of adherence at a Prevention of ...Mother-to-Child HIV Transmission (PMTCT) Center before and during the COVID-19 pandemic. This study was conducted from a cohort of PLWH who received prenatal care and were virally suppressed near delivery. We tracked combined antiretroviral therapy (cART) pickups for 12 months and HIV viral load (VL) from 2 to 12 months after delivery. We defined flexible adherence as a monthly pickup of cART and strict adherence as also having VL < 200 copies/mL and at least one maternal HIV VL between two and twelve months postpartum. Pre-pandemic was defined as delivery from March 2017-February 2019 and pandemic as March 2020-February 2022. During the study, 1119 PLWH were followed, and 965 (86%) were suppressed near delivery. There were 511 pre-pandemic and 290 pandemic participants. Adherence rates were 66/511 (13%) and 38/290 (13%), respectively. During the pandemic, more participants conceived using cART and were undetectable at the start of prenatal care; nevertheless, postpartum adherence was no better than pre-pandemic underscoring the need to improve strategies for adherence specific to this subset of PLWH in the postpartum period.
Objective
This study investigated the association between periodontitis severity (exposure) and metabolic syndrome (MetS - outcome), using two criteria for diagnosis of the outcome, since this ...relationship remains unexplored.
Materials and methods
A case-control study was conducted with 870 individuals: 408 with first MetS diagnosis (cases) and 462 without MetS (controls). Participants’ general information was obtained using a questionnaire and laboratory data was collected from medical records. Periodontitis severity criteria followed the Center for Disease Control and Prevention: none, mild, moderate, and severe. Odds ratios (OR) and 95% confidence intervals (95% CI) were determined by logistic regression analysis.
Results
Findings showed a positive association between moderate and severe periodontitis and MetS: OR
adjusted
= 1.64 (95% CI: 1.01 to 2.68) and OR
adjusted
= 1.94 (95% CI: 1.19 to 3.16), respectively, after adjustment for age, sex, schooling level, smoking habit, and cardiovascular disease. The adjusted measurements showed that among individuals with moderate or severe periodontitis, the probability of having MetS was around two times greater than among those without periodontitis, and that the chance was greater among participants with severe periodontitis than those with moderate periodontitis.
Conclusion
An association between the severity of periodontal status and MetS was found, suggesting a possible relationship between the two diseases.
Clinical relevance
MetS influences the etiology of cardiovascular diseases, one of the leading causes of mortality worldwide. The findings suggest that the greater the severity of periodontitis, the greater is the association magnitude with MetS. The health professional needs to recognize that the importance of periodontal disease may play in MetS.
Organic–inorganic (O–I) hybrid nanocomposites have already been widely investigated in the optoelectronic industry and are emerging in the biomedical field. In both cases, a thorough knowledge of the ...O–I hybrid morphology is key for reaching tailored properties of the devices; however, up to now little is known on this matter. Herein, we used advanced X-ray scattering and microscopy techniques to investigate in detail the morphology and nanostructure of a biocompatible, ternary, and semicrystalline O–I hybrid nanocomposite made up of poly(
ε
-caprolactone) (PCL) and poly(ethylene glycol) (PEG), cross-linked by in situ-generated silsesquioxane structures (SS). Results showed that phase separation occurred at all length scales. At the microscale, irreversible PCL/PEG phase separation generated a globular morphology, where PEG-rich spherical domains were uniformly distributed within a PCL-rich matrix. At the nanoscale, partial organic/inorganic phase segregation resulted in the formation of polysilsesquioxane nanoparticles in both matrix and domains. Finally, an unusual crystalline behaviour was observed for the ternary O–I hybrid nanocomposite, PCL-PEG/SS, where PCL crystallization was anticipated and PEG crystallization was delayed in comparison with the binary PCL/SS and PEG/SS O–I hybrids as well as to a blend of the uncross-linked PCL and PEG precursors. These results provide new insights on how the competing processes of phase separation, crystallization, and inorganic cross-linking affect the overall morphology and nanostructure of O–I hybrid nanocomposites and, therefore, might be useful for establishing relevant structure–property relationships.
Graphical abstract
Nanoparticle morphology, size and dispersion are key parameters for the application of cellulose nanomaterials in various areas, such as polymer nanocomposites, catalysts, gel and so on. Transmission ...electron microscopy (TEM) is the most suitable technique for the morphological characterization of these particles. However, nanocellulose low contrast in TEM images is the major drawback for their adequate morphological characterization and size determination. Even though it is widespread knowledge that negative staining using uranyl acetate is the best approach for intensifying cellulose contrast, up to now few have succeeded in achieving high quality images and reliable size measurements of these nanomaterials. This protocol presents an optimization of the standard uranyl acetate protocol commonly used for biological specimens in order to suit cellulose nanomaterials. Drying method and grid conditions were proven to be the most significant variables for effective TEM specimen preparation. These guidelines could also be successfully applied to enhance the cellulose nanomaterial contrast in polymer matrices.
The cytotoxic activity of the pimarane diterpene annonalide (1) and nine of its semisynthetic derivatives (2–10) was investigated against the human tumor cell lines HL-60 (leukemia), PC-3 (prostate ...adenocarcinoma), HepG2 (hepatocellular carcinoma), SF-295 (glioblastoma) and HCT-116 (colon cancer), and normal mouse fibroblast (L929) cells. The preparation of 2–10 involved derivatization of the side chain of 1 at C-13. Except for 2, all derivatives are being reported for the first time. Most of the tested compounds presented IC50s below 4.0 μM, being considered potential antitumor agents. The structures of all new compounds were elucidated by spectroscopic analyses including 2D NMR and HRMS. Additionally, the interaction of annonalide (1) with ctDNA was evaluated using spectroscopic techniques, and the formation of a supramolecular complex with the macromolecule was confirmed. Competition assays with fluorescent probes (Hoechst and ethidium bromide) and theoretical studies confirmed that 1 interacts preferentially via DNA intercalation with stoichiometric ratio of 1:1 (1:ctDNA). The ΔG value was calculated as −28.24 kJ mol−1, and indicated that the interaction process occurs spontaneously. Docking studies revealed that van der Walls is the most important interaction in 1-DNA and EB-DNA complexes, and that both ligands (1 and EB) interact with the same DNA residues (DA6, DA17 and DT19).
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•Nine derivatives of the pimarane diterpene annonalide were prepared by semisynthesis.•The cytotoxic activity of annonalide and its semisynthetic derivatives was investigated against five tumor cell lines.•Interaction studies suggested that annonalide interacts with ctDNA by intercalation.•The cytotoxic activity of annonalide may be associated with its interaction with DNA.
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