Cardiovascular 3D bioprinting:A review on cardiac tissue development

Cardiovascular diseases such as myocardial infarction account for millions of worldwide deaths annually. Cardiovascular tissues constitute a highly organized and complex three-dimensional (3D) structure that makes them hard to fabricate in a biomimetic manner by conventional scaffold fabrication methods. 3D bioprinting has been introduced as a novel cell-based method in the last two decades due to its ability to recapitulate cell density, multicellular architecture, physiochemical environment, and vascularization of biological constructs with accurate designs. This review article aims to provide a comprehensive outlook to obtain cardiovascular functional tissues from the engineering of bioinks comprising cells, hydrogels, and biofactors to bioprinting techniques and relevant biophysical stimulations responsible for maturation and tissue-level functions. Also, cardiac tissue 3D bioprinting investigations and further discussion over its challenges and perspectives are highlighted in this review article

Novel Layered Double Hydroxides-Hydroxyapatite/gelatin Bone Tissue Engineering Scaffolds: Fabrication, Characterization, and in Vivo Study

Developing Porous Biodegradable Scaffolds through Simple Methods is One of the Main Approaches of Bone Tissue Engineering (BTE). in This Work, a Novel BTE Composite Containing Layered Double Hydroxides (LDH), Hydroxyapatite (HA) and Gelatin (GEL) Was Fabricated using Co-Precipitation and Solvent-Casting Methods. Physiochemical Characterizations Showed that the Chemical Composition and Microstructure of the Scaffolds Were Similar to the Natural Spongy Bone. Interconnected Macropores Ranging over 100 to 600 Μm Were Observed for Both Scaffolds While the Porosity of 90 ± 0.12% and 92.11 ± 0.15%, as Well As, Young\u27s Modulus of 19.8 ± 0.41 and 12.5 ± 0.35 GPa Were Reported for LDH/GEL and LDH-HA/GEL Scaffolds, Respectively. the Scaffolds Were Degraded in Deionized Water after a Month. the SEM Images Revealed that between Two Scaffolds, the LDH-HA/GEL with Needle-Like Secondary HA Crystals Showed Better Bioactivity. According to the Alkaline Phosphatase Activity and Alizarin Red Staining Results, LDH-HA/GEL Scaffolds Demonstrated Better Bone-Specific Activities Comparing to LDH/Gel Scaffold as Well as Control Sample (P \u3c 0.05). the Rabbit Adipose Stem Cells (ASCs) Were Extracted and Cultured, Then Seeded on the LDH-HA/GEL Scaffolds after Confluence. Three Groups of Six Adult Rabbits Were Prepared: The Scaffold + ASCs Group, the Empty Scaffold Group and the Control Group. the Critical Defects Were Made on the Left Radius and the Scaffolds with or Without ASCs Were Implanted There While the Control Group Was Left Without Any Treatment. All Animals Were Sacrificed after 12 Weeks. Histomorphometric Results Showed that the Regeneration of Defects Was Accelerated by Scaffold Implantation But ASC-Seeding Significantly Improved the Quality of New Bone Formation (P \u3c 0.05). the Results Confirmed the Good Performance of LDH-HA/GEL Scaffold to Induce Bone Regeneration

Effect of Amino-Functionalization on Insulin Delivery and Cell Viability for Two Types of Silica Mesoporous Structures

Inorganic Mesoporous Structures Are a Class of Novel Biomaterials that Have Shown Practical Applications in Delivery of a Variety of Therapeutic Agents. in the Present Study, Two Mesoporous Structures Were Prepared, and the Effect of Surface Modification on their Insulin Delivery and in Vitro Cytotoxicity Was Evaluated. Morphological and Structural Characterizations of Silica Particles Were Accomplished by Different Analytical Techniques, Including Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) Surface Area Analyses. the Drug Loading Capacity and in Vitro Drug Release Behavior of Silica Structures Were Investigated under Simulated Gastrointestinal Conditions and Phosphate-Buffered Saline Solution using FTIR and UV–Vis Spectroscopy. in Vitro Cytotoxicity Evaluation Was Carried Out Via MTT Assay. Results Showed that the Morphology of MCM-41 Was Round, While SBA-15 Was Wheat Like, Both Possessed Almost Homogeneous Size Distribution. Also, Modification with Amine Did Not Influence the Morphology and Structure of the Particles. Both MCM-41 and SBA-15 Particles Were Found to Have Narrow Pore-Size Distributions of 2.8 and 6.8 Nm, Respectively. SBA-15 Particles Demonstrated a High Insulin Loading Capacity of About 15.1 %, While MCM-41 and Modified MCM-41 (MMCM-41) Were Observed to Load Virtually No Insulin at All. the Surface Modification by Amino Groups Resulted in Higher Insulin Loading and the Slower Rate of Release for Modified SBA-15 (MSBA-15) Compared to the Non-Modified SBA-15 (SBA-15). According to the Cytotoxicity Evaluation Results, All of the Samples Showed Cytotoxicity Grade 0–1, in a Concentration-Dependent Manner. Moreover, Insulin-Loaded MSBA-15 Particles Exhibited Higher Cell Viability Compared to the Others. It Was Concluded that Amine Modification of SBA-15 Could Result in Higher Loading and Extended Release of Insulin and More Cell Viability

Biological Evaluation of a Novel Tissue Engineering Scaffold of Layered Double Hydroxides (LDHs)

Bone Tissue Engineering (BTE) Composed of Three Main Parts: Scaffold, Cells and Signaling Factors. Several Materials and Composites Are Suggested as a Scaffold for BTE. Biocompatibility is One of the Most Important Property of a BTE Scaffold. in This Work Synthesis of a Novel Nanocomposite Including Layered Double Hydroxides (LDH) and Gelatin is Carried Out and its Biological Properties Were Studied. the Co-Precipitation (PH=11) Method Was Used to Prepare the LDH Powder, using Calcium Nitrate, Magesium Nitrate and Aluminum Nitrate Salts as Starting Materials. the Resulted Precipitates Were Dried. X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) Analyses Were Used to Characterize the Synthesized Powders. the Results Demonstrated the Presence of Nanocrystals of Ca-LDH and Mg-LDH as Hexagonal and Layered Morphology. the Obtained Powders Were Composed to Gelatin Via Solvent Casting Method Then Freez Dried. the Scaffold Was Prepared Via Membrane Lamination Method from the Resulted Layers that Linked Together with Gelatin as Binder. in Order to Investigate the Scaffold Cytotoxicity MTT Assay Was Done with a Osteosarcoma Cell Line. No Toxic Response Was Observed in Specimens. as a Major Result, It Was Demonstrated that the Specimen Showed a Significant Cellular Response. Then Osteosarcoma Cells Were Cultured for 7-Day and 14-Day Extract of Powders. the Composites Osteoconductivity Was Investigate with Cells Alkaline Phosphatase Extraction. the Results Demonstrated that the Ca-LDH/gelatin Composite Scaffold Has a Good Potential for Bone Tissue Engineering Applications and Mg-LDH Specimen Has a Better Osteconductivity. © (2012) Trans Tech Publications

Synthesis and Characterization of Hydroxyapatite Nanocrystalsvia Chemical Precipitation Technique: Synthesis and characterization of hydroxyapatite

In this study, hydroxyapatite (HA) nanocrystals have been synthesized via chemical precipitation technique. Diammonium hydrogen phosphate and calcium nitrate 4-hydrate were used as starting materials and sodium hydroxide solution was used as the agent for pH adjustment. The powder sample was evaluated by techniques such as scanning electron microscope, transmission electron microscope, Fourier transform infra-red spectroscopy, differential thermal analysis, thermal gravimetric analysis, X-ray diffraction, atomic absorption spectroscopy and EDTA titrationan alyses. According to the above-experimental results, it was found that hydroxyapatite nanocrystals can successfully be produced through wet precipitation method. The bulk Ca/Pmolar ratio of synthesized hydroxyapatite was determined as 1.71 that was higher than stoichiometric ratio (1.667) which is expected for a pure HAphase. Finally, transmission electron microscopic technique demonstrated that the crystallites of prepared powder were nanosized with a needle-like morphology

Mechanical behavior of calcium sulfate scaffold prototypes built by solid free-form fabrication

Purpose: This paper aims to investigate the mechanical behavior of three-dimensional (3D) calcium sulfate porous structures created by a powder-based 3D printer. The effects of the binder-jetting and powder-spreading orientations on the microstructure of the specimens are studied. A micromechanical finite element model is also examined to predict the properties of the porous structures under the load. Design/methodology/approach: The authors printed cylindrical porous and solid samples based on a predefined designed model to study the mechanical behavior of the prototypes. They investigated the effect of three main build bed orientations (x, y and z) on the mechanical behavior of solid and porous specimens fabricated in each direction then evaluated the micromechanical finite-element model for each direction. The strut fractures were analyzed by scanning electron microscopy, micro-computed tomography and the von Mises stress distribution. Findings: Results showed that the orientation of powder spreading and binder jetting substantially influenced the mechanical behavior of the 3D-printed prototypes. The samples that were fabricated parallel to the applied load had higher compressive strength compared with those printed perpendicular to the load. The results of the finite element analysis agreed with the results of the experimental mechanical testing. Research limitations/implications: The mechanical behavior was studied for the material and the 3D-printing machine used in this research. If one were to use another material formulation or machine, the printing parameters would have to be set accordingly. Practical implications: This work aimed to re-tune the control factors of an existing rapid prototyping process for the given machine. The authors achieved these goals without major changes in the already developed hardware and software architecture. Originality/value: The results can be used as guidelines to set the printing parameters and a model to predict the mechanical properties of 3D-printed objects for the development of patient- and site-specific scaffolds

Nano-graphene oxide and vitamin D delivery

One of the Most Interesting and Recent Insights into Biomimetic Scaffold Nano-Biomaterial is Smart Scaffolding with Targeted Drug Delivery Ability. in Recent Decades, the Use of Graphene-Based Materials, Such as Nano-Graphene Oxide (NGO), as a Drug Carrier with Amphiphilic Properties, Has Attracted Considerable Attention of Scientists and Researchers in This Field. in Addition, One of the Important Global Problems is Increased Vitamin D Deficiency, Particularly in Pregnant and Postmenopausal Women. Therefore, in This Work, by Considering Hydrophobic Properties of Vitamin D, We Attempted to Examine its Loading and Release Both in the Presence of Surfactant and Surfactant-Free NGO-Aqueous Solution. at First, NGO Powder Was Synthesized by the Modified Hummer\u27s Method. after the Preparation of Vitamin D and Tween 80 (TW) Solution, They Were Added to NGO Aqueous Solution. Simultaneously, the Next Vitamin D and NGO Aqueous Solution Was Prepared in a Surfactant-Free Mode. in Order to Evaluate the Loading Content, Both Solutions Were Centrifuged, and their Supernatant Was Analyzed by UV-Visible Spectroscopy. Additionally, FTIR Spectroscopy Was Employed to Determine the TW 80 Effects on Vitamin D and NGO. the Results Have Shown that Vitamin D Loading in Surfactant-Free Solution Was Approximately 0% While in the Presence of TW 80 It Was 75.37% ± 4.12. Therefore, the Combination of Vitamin D, TW 80, and NGO Can Be a Suitable Candidate for Carrying Hydrophobic Drugs in Smart Scaffolding, Especially in Bone Tissue Engineering