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3D printing of chitosan hydrogels has attracted wide interest because of their excellent biocompatibility, antibacterial activities, biodegradability, zero toxicity and low cost. However, chitosan inks are often involved in toxic and organic solvents. Moreover, the recently reported 3D-printed chitosan scaffolds lack enough strength, thus limiting their use in tissue engineering. Here, we reported a chitosan ink obtained by dissolving chitosan into an alkali aqueous solution. This chitosan ink is a stable solution at low temperature (5 °C), but once heated, the chitosan chains self-assemble to lead to gelation. Based on this principle, a corresponding direct ink writing (DIW) method was developed to print high-strength chitosan hydrogels. Specifically, the chitosan ink was extruded into heated deionized water to complete the in situ gelation. The temperature of the nozzle and hot water was well controlled to keep the printing process stable. The rheological behavior of the chitosan ink was investigated and the printing parameters were systematically studied to print chitosan hydrogel scaffolds with high quality and high strength. Based on these, high-strength (2.31 MPa for compressive strength) and complex chitosan hydrogel structures can be directly printed. The cell culture and the wound healing results further show that the printed chitosan scaffolds with this method have great potential in tissue engineering.

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In this work, Mn-doped ZnS quantum dots capped by L-cysteine (Mn@ZnS/L-cyst) and polyethylene glycol (Mn@ZnS/PEG) and also Mn-doped ZnS on zeolite NaY (Mn@ZnS/Y) were synthesized. These compounds were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible and fluorescence spectroscopy. Then, the photodegradation ability of these three photocatalysts was investigated for degradation of 4',5'-dibromofluorescein dye under ultraviolet irradiation. In the next stage, the different effective parameters on degradation performance, such as pH, catalyst dosage, and initial dye concentration, were studied. Results demonstrated that the optimum initial concentration was 40 mg L-1 for all three catalysts. The optimum catalyst dosage for both Mn-doped ZnS quantum dots capped by L-cysteine and Mn-doped ZnS on zeolite NaY was 0.017 g L-1 and for Mn-doped ZnS quantum dots capped by polyethylene glycol was 0.033 g L-1. The degradation efficiency of 97% for all three photocatalysts was achieved; therefore, by considering the higher production yield of quantum dots onto zeolite and also the more convenient recovery of the Mn-doped ZnS on zeolite NaY from the solution, it seems synthesis of quantum dots onto the zeolites is a reasonable strategy.

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Hydrogel structures equipped with internal microchannels offer more in vivo-relevant models for construction of tissues and organs in vitro. However, currently used microfabrication methods of constructing microfluidic devices are not suitable for the handling of hydrogel. This study presents a novel method of fabricating hydrogel-based microfluidic chips by combining the casting and bonding processes. A twice cross-linking strategy is designed to obtain a bonding interface that has the same strength with the hydrogel bulk, which can be applied to arbitrary combinations of hydrogels. It is convenient to achieve the construction of hydrogel structures with channels in branched, spiral, serpentine, and multilayer forms. The experimental results show that the combination of gelatin and gelatin methacrylate (GelMA) owns the best biocompatibility and can promote cell functionalization. Based on these, a vessel-on-a-chip system with vascular function in both physiological and pathological situations is established, providing a promising model for further investigations such as vascularization, vascular inflammation, tissue engineering, and drug development. Taken together, a facile and cytocompatible approach is developed for engineering a user-defined hydrogel-based chip that can be potentially useful in developing vascularized tissue or organ models.

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Hydrogel microspheroids are widely used in tissue engineering, such as injection therapy and 3D cell culture, and among which, heterogeneous microspheroids are drawing much attention as a promising tool to carry multiple cell types in separated phases. However, it is still a big challenge to fabricate heterogeneous microspheroids that can reconstruct built-up tissues' microarchitecture with excellent resolution and spatial organization in limited sizes. Here, a novel airflow-assisted 3D bioprinting method is reported, which can print versatile spiral microarchitectures inside the microspheroids, permitting one-step bioprinting of fascinating hydrogel structures, such as the spherical helix, rose, and saddle. A microfluidic nozzle is developed to improve the capability of intricate cell encapsulation with heterotypic contact. Complex structures, such as a rose, Tai chi pattern, and single cell line can be easily printed in spheroids. The theoretical model during printing is established and process parameters are systematically investigated. As a demonstration, a human multicellular organoid of spirally vascularized ossification is reconstructed with this method, which shows that it is a powerful tool to build mini tissues on microspheroids.

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Iron overload may contribute to brain damage that involves delayed brain atrophy, edema, and neuronal cell death as well as unfavorable outcome following ischemic stroke and intracerebral hemorrhage (ICH). This prospective study was performed to determine the association of serum ferritin level, an iron storage protein, with perihematoma edema (PHE) growth as well as in-hospital mortality and long-term clinical outcome of patients with ICH. Data was collected from patients with ICH from February 2011 to April 2012. Demographic and clinical data were recorded and serum ferritin was measured on admission. Brain CT scan was performed on admission and 72 hours later. Volume of hematoma and PHE was calculated using ABC/2 formula. Functional outcome was assessed using modified Rankin Scale. A total of 63 patients were included in this study, of those 11 (17.5%) patients died during the first 72 hours of admission. There was a significant correlation between PHE growth during first 72 hours of hospitalization and serum ferritin (P<0.001) as well as history of diabetes mellitus (P<0.001). PHE growth during the first 72-hours of hospitalization and baseline hematoma volume were both predictors of in-hospital mortality and poor outcome (P=0.026 and P=0.035, respectively). These results indicate the role of iron overload in the development of PHE following ICH. However, it seems that serum ferritin level is not directly associated with in-hospital mortality and long-term functional outcome.

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OBJECTIVES: Preclinical studies show that iron plays a key role in mediating neuronal injury. This study was performed in order to identify the relationship between the serum level of ferritin and severity of the brain injury which occur after an Intracerebral hemorrhage (ICH). MATERIALS AND METHODS: This was a cross sectional descriptive - analytic study, which was conducted on those patients who had suffered from an ICH and had attended Poursina Hospital. The Serum levels of ferritin were measured at admittance. A Cranial CT scan was performed at admission and also 72 hr afterward. Hematoma and edema surrounding the hematoma volumes were also measured at entrance and 72 hr afterward. Data analysis was carried out by a descriptive - analytic statistics approach and calculated later on by the Spss-20 software. RESULTS: In this investigation, 63 patients were studied, from which 34 (54%) were male and 29 (46%) female. The average age of the patients was 69.7± 11.9 (Min 43 and Max 94 years old). A significant relationship was observed between the level of ferritin and the edema volume surrounding the hematoma at first and next 72 hr after the patients were admitted. CONCLUSION: These results delineated the effective role of iron on the edema volume elevation. More studies are essentially urged to ascertain the clinical evaluation of the curing effect of iron chelators in those patients who suffer from ICH.

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BACKGROUND: Although the precise etiology of multiple sclerosis (MS) is unknown, it seems that both genetic and environmental factors are important. Recent studies suggest that low serum vitamin D levels are important environmental factor in MS. The aim of this study was to compare the serum levels of vitamin D between MS patients and healthy subjects, and to determine its association with disability in MS patients. METHODS: In this cross-sectional study, a total of 52 patients with MS were randomly recruited and matched for age and sex with 52 healthy subjects. Demographic characteristics and serum vitamin D levels for both groups, as well as duration of disease Expanded Disability Status Scale (EDSS) for MS patients were evaluated. Statistical analysis was performed by independent samples t-test and multiple linear regression analysis. RESULTS: The mean serum vitamin D levels were 26.5 ± 16.3 ng/ml in MS patients vs. 37.1 ±19.7 in healthy subjects (P = 0.003). A linear regression analysis showed no significant association between vitamin D levels and EDSS score of patients with MS (P = 0.345), after adjusting for the covariates. CONCLUSION: Our findings did not suggest a protective association for serum vitamin D levels against disability in MS patients.