Preparation and Characterization of n-HA/Chitosan Scaffold Prepared by a New Method of Emulsion-Foaming/Freeze-Drying Process

2007 ◽  
Vol 544-545 ◽  
pp. 789-792 ◽  
Author(s):  
Li Zhang ◽  
Yu Bao Li ◽  
Pu Jiang Shi ◽  
Yi Zuo ◽  
Lan Wu
Keyword(s):  
Compressive Strength ◽  
Freeze Drying ◽  
Cell Attachment ◽  
Composite Scaffold ◽  
Testing Machine ◽  
Calculated Data ◽  
Tween 80 ◽  
New Method ◽  
High Porosity ◽  
Drying Process

A novel nano-hydroxyapatite/chitosan (n-HA/CS) composite scaffold with high porosity was developed by a new method of emulsion-foaming/freeze-drying process and was characterized by means of infrared spectroscopy (IR), scanning electronic microscopy (SEM) and universal material testing machine. In addition, the porosity and density of the scaffold were also calculated. IR result shows that the characteristic absorption peaks belonging to both CS and HA are present in their composite, and the slight band-shifts and peak-decrease suggest that some interactions have taken place between the two phases of CS and n-HA in the composite. SEM photo displays that, with the dosage increase of Tween-80, the prepared scaffold shows highly porous and interconnected structure, in which macropores and micropores coexist. The calculated data demonstrate that the porosity of the scaffold is proportional to the content of the emulsifier, while the compressive strength is inversely. When 15wt% emulsifier used, the porosity of the scaffold can be up to 90% and the density is 0.453g/cm3, while the corresponding compressive strength is about 2.4MPa. The newly developed n-HA/CS composite scaffolds may serve as a good 3-D substrate for cell attachment and migration in bone tissue engineering.

Preparation and Characterization of the Porous Hydroxyapatite/Silk Fibroin Composite Scaffolds with Interconnected Ducts

2008 ◽  
Vol 368-372 ◽  
pp. 1190-1193 ◽  
Author(s):  
Jing Wang ◽  
Mu Qin Li ◽  
Xiang Cai Meng ◽  
Guang Wu Wen
Keyword(s):  
Compressive Strength ◽  
Silk Fibroin ◽  
Freeze Drying ◽  
Composite Scaffold ◽  
Drying Process ◽  
X Ray Diffraction ◽  
Composite Scaffolds ◽  
Porous Hydroxyapatite ◽  
X Ray

Porous hydroxyapatite (HA) bioceramic matrix with interconnected ducts was obtained using a porogen burnout technique at 1200°C. The HA/silk fibroin (SF) composite scaffolds were developed with the SF sponges formed inside the pores and ducts of the bioceramics by first introducing HA/SF slurries into the pores and ducts followed by a freeze-drying process. Phase components and morphology of materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Porosity was measured by Archimedean method. Compressive strength was also measured. The simulated body fluids (SBF) experiments were conducted to evaluate bioactivity. The results show that hydroxyapatite is the main phase compositions after sintering at 1200°C. The porosity of composite scaffolds reaches 70%~80%. The sizes of pores and ducts of HA matrix range from 150μm to 400μm and the pore sizes of SF sponges formed inside the macroporous structure of bioceramics are approximately 100μm,a structure favorable for bone tissue in-growth. The compressive strength of the composite scaffolds is greatly improved in comparison with that of HA matrix. In the SBF tests, a layer of randomly oriented apatite crystals form on the scaffold surface after sample immersion in SBF. The cell culture experiments show that the osteoblast cells are attached and proliferated on the surface of the composite scaffold, which suggest good bioactivity and cellular compatibility of the composite material.

Preparation and properties of biodegradable polymer/nano-hydroxyapatite bioceramic scaffold for spongy bone regeneration

2019 ◽  
Vol 39 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Mohammed Mizanur Rahman ◽  
Md. Shahruzzaman ◽  
Md. Sazedul Islam ◽  
M. Nuruzzaman Khan ◽  
Papia Haque
Keyword(s):  
Compressive Strength ◽  
Biodegradable Polymer ◽  
Composite Scaffold ◽  
Sol Gel ◽  
Nanocrystalline Structure ◽  
Poly Lactic Acid ◽  
Cytotoxicity Test ◽  
High Porosity ◽  
Spongy Bone ◽  
Excellent Thermal Stability

Abstract Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of conventional ceramic bone substitutes, such as brittleness and difficulty in shaping. To better mimic the mineral components and microstructure of natural bone, a novel nano-hydroxyapatite (nHAp)–chitosan composite scaffold including gelatin and polymer (poly(lactic acid)) with high porosity was developed using a sol-gel method and subsequently lyophilized for efficient bone tissue engineering. The nanocrystalline structure of hydroxyapatite was observed using X-ray diffraction analysis and the composite showed crystallinity due to the presence of nHAp. The pore diameter of the composite containing 5% nHAp was found to be 125 μm, while the composites with 10%, 15%, and 20% nHAp revealed a smaller pore size in the range of 15–28 μm. The highest compressive strength of 5.5 MPa was observed for the 10% nHAp-containing scaffold, whereas thermogravimetric analysis showed 90%–94% degradation at a temperature of 600°C, which demonstrated its excellent thermal stability. Antibacterial and cytotoxicity test results revealed that the composite is resistant toward microbial attack and has low sensitivity in cytotoxicity. The compressive strength data suggests that the composite does not have enough strength as that of human compact bone; however, the highly porous structure as observed in scanning electron microscopy makes it possible for use as an excellent substrate in the spongy bone of humans.

scholarly journals The effect of excipients on the stability and aerosol performance of salmon calcitonin dry powder inhalers prepared via the spray freeze drying process

2016 ◽  
Vol 66 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Narges Poursina ◽  
Alireza Vatanara ◽  
Mohammad Reza Rouini ◽  
Kambiz Gilani ◽  
Abdolhossein Rouholamini Najafabadi
Keyword(s):  
Salmon Calcitonin ◽  
Freeze Drying ◽  
Tween 80 ◽  
Drying Process ◽  
Dry Powders ◽  
Aerosol Performance ◽  
Inhalation Delivery ◽  
Spray Freeze Drying ◽  
The Stability ◽  
Structurally Stable

Abstract Spray freeze drying was developed to produce dry powders suitable for applications such as inhalation delivery. In the current study, the spray freeze drying technique was employed to produce inhalable salmon calcitonin microparticles. Effects of the carrier type, concentration of hydroxyl propyl-β-cyclodextrin and the presence of Tween 80 on the chemical and structural stability, as well as on the aerosol performance of the particles were investigated. The results indicated that hydroxyl propyl-β-cyclodextrin had the most important effect on the chemical stability of the powder and strongly increased its stability by increasing its concentration in the formulation. Chemically stable formulations (over 90 % recovery) were selected for further examinations. Fluorescence spectroscopy and circular dichroism suggested that the formulations were structurally stable. Aerosol performance showed that the Tween-free powders produced higher fine particle fraction values than the formulations containing Tween (53.7 vs. 41.92 % for trehalose content and 52.85 vs. 43.06 % for maltose content).

Fabrication of water-soluble loose-fill foam from tamarind (Tamarindus indica L.) seed polysaccharide by mechanical frothing and freeze-drying process

2020 ◽  
pp. 0021955X2094856
Author(s):  
Ladawan Songtipya ◽  
Ponusa Songtipya ◽  
Thummanoon Prodpran ◽  
Ekwipoo Kalkornsurapranee ◽  
Jobish Johns
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Freeze Drying ◽  
Moisture Absorption ◽  
Cell Structure ◽  
Water Soluble ◽  
Drying Process ◽  
Uniform Size ◽  
Cell Window ◽  
Loose Fill

The water-soluble loose-fill foam obtained from tamarind seed polysaccharide (TSP) was successfully prepared by a combination of mechanical frothing and freeze-drying process. The effects of TSP concentration, plasticizer content, and surfactant content on the cellular morphology, physical properties, mechanical properties, and moisture absorption were investigated. The cellular structure of TSP foam exhibited an open cell structure with a non-uniform size of the cell window, and the density varied in a range of ∼0.006–0.106 g/cm3. Foam preparation with high TSP concentration, low plasticizer as well as glycerol content enhanced the mechanical properties of the obtained foam, including tensile strength, compressive strength, and hardness. The high compressive strength of TSP foams up to ∼1.03 MPa can be produced which demonstrates that TSP foam is capable to use as a loose-fill product.

scholarly journals Surface Treatment of Glass Vials for Lyophilization: Implications for Vacuum-Induced Surface Freezing

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1766
Author(s):  
Francesco Regis ◽  
Andrea Arsiccio ◽  
Erwan Bourlès ◽  
Bernadette Scutellà ◽  
Roberto Pisano
Keyword(s):  
Freeze Drying ◽  
Blow Up ◽  
Tween 80 ◽  
Drying Process ◽  
Hydrophobic Coatings ◽  
Promising Strategy ◽  
Successful Induction ◽  
Hydrophilic Coatings ◽  
Surface Freezing ◽  
Cycle Efficiency

Freeze-drying is commonly used to increase the shelf-life of pharmaceuticals and biopharmaceuticals. Freezing represents a crucial phase in the freeze-drying process, as it determines both cycle efficiency and product quality. For this reason, different strategies have been developed to allow for a better control of freezing, among them, the so-called vacuum-induced surface freezing (VISF), which makes it possible to trigger nucleation at the same time in all the vials being processed. We studied the effect of different vial types, characterized by the presence of hydrophilic (sulfate treatment) or hydrophobic (siliconization and TopLyo Si–O–C–H layer) inner coatings, on the application of VISF. We observed that hydrophobic coatings promoted boiling and blow-up phenomena, resulting in unacceptable aesthetic defects in the final product. In contrast, hydrophilic coatings increased the risk of fogging (i.e., the undesired creeping of the product upward along the inner vial surface). We also found that the addition of a surfactant (Tween 80) to the formulation suppressed boiling in hydrophobic-coated vials, but it enhanced the formation of bubbles. This undesired bubbling events induced by the surfactant could, however, be eliminated by a degassing step prior to the application of VISF. Overall, the combination of degasification and surfactant addition seems to be a promising strategy for the successful induction of nucleation by VISF in hydrophobic vials.

Strong and Bioactive Tri-Calcium Phosphate Scaffolds with Tube-Like Macropores

2014 ◽  
Vol 19 ◽  
pp. 65-75 ◽  
Author(s):  
Wei Zheng ◽  
Gang Liu ◽  
Cheng Yan ◽  
Yin Xiao ◽  
Xi Geng Miao
Keyword(s):  
Tissue Engineering ◽  
Compressive Strength ◽  
Calcium Phosphate ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Cell Attachment ◽  
High Porosity ◽  
Calcium Phosphate Ceramic ◽  
Si Doped ◽  
Butadiene Styrene

Calcium phosphate ceramic scaffolds have been widely investigated for bone tissue engineering due to their excellent biocompatibility and biodegradation. Unfortunately, they have low mechanical properties, which inversely restrict their wide applications in load-bearing bone tissue engineering. In this study, porous Si-doped tri-calcium phosphate (TCP) ceramics with a high porosity (~65%) and with interconnected macrotubes (~0.8mm in diameter) and micropores (5-100 μm) were prepared by firing hydroxyapatite (HA)/ bioactive glass-impregnated acrylontrile butadiene styrene (ABS) templates at 1400 °C. Results indicated that the cylindrical scaffolds had a higher compressive strength than the cubic scaffolds and the smallest cylindrical scaffold had a highest compressive strength (14.68+0.2MPa). Additional studies of cell attachment and MTT cytotoxicity assay proved the bioactivity and biocompatibility of the Si-doped TCP scaffolds.

A NEW METHOD OF PREPARATION OF AEROGEL-LIKE MATERIALS USING A FREEZE-DRYING PROCESS

1989 ◽  
Vol 24 (C4) ◽  
pp. C4-29-C4-32 ◽  
Author(s):  
D. KLVANA ◽  
J. CHAOUKI ◽  
M. REPELLIN-LACROIX ◽  
G. M. PAJONK
Keyword(s):  
Freeze Drying ◽  
New Method ◽  
Drying Process

Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 16-17
Author(s):  
Alan S. Rudolph ◽  
Ronald R. Price
Keyword(s):  
Real Time ◽  
Self Assembly ◽  
Freeze Drying ◽  
Video Capture ◽  
Drying Process ◽  
Artificial Membranes ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Spherical Structures ◽  
Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

Controlling porosity and density of nanocellulose aerogels for superhydrophobic light materials

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 145-153 ◽  
Author(s):  
Chengua Yu ◽  
Feng Wang ◽  
Shiyu Fu ◽  
Lucian Lucia
Keyword(s):  
Contact Angle ◽  
Freeze Drying ◽  
Engine Oil ◽  
High Porosity ◽  
Water Mixture ◽  
Waste Engine Oil ◽  
Hydrophobically Modified ◽  
Static Contact ◽  
Oil Water ◽  
Hydrophobic Material

A very low-density oil-absorbing hydrophobic material was fabricated from cellulose nanofiber aerogels–coated silane substances. Nanocellulose aerogels (NCA) superabsorbents were prepared by freeze drying cellulose nanofibril dispersions at 0.2%, 0.5%, 0.8%, 1.0%, and 1.5% w/w. The NCA were hydrophobically modified with methyltrimethoxysilane. The surface morphology and wettability were characterized by scanning electron microscopy and static contact angle. The aerogels displayed an ultralow density (2.0–16.7 mg·cm-3), high porosity (99.9%–98.9%), and superhydrophobicity as evidenced by the contact angle of ~150° that enabled the aerogels to effectively absorb oil from an oil/water mixture. The absorption capacities of hydrophobic nanocellulose aerogels for waste engine oil and olive oil could be up to 140 g·g-1 and 179.1 g·g-1, respectively.

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