scholarly journals Development and Optimization of the Novel Fabrication Method of Highly Macroporous Chitosan/Agarose/Nanohydroxyapatite Bone Scaffold for Potential Regenerative Medicine Applications

Biomolecules ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 434 ◽  
Author(s):  
Paulina Kazimierczak ◽  
Krzysztof Palka ◽  
Agata Przekora
Keyword(s):  
Regenerative Medicine ◽  
Compression Test ◽  
Freeze Drying ◽  
High Porosity ◽  
The Novel ◽  
Bone Scaffold ◽  
Simultaneous Application ◽  
Foaming Agent ◽  
Novel Scaffold ◽  
Gas Foaming

Bone scaffolds mimicking the three-dimensional bone structure are of essential importance for bone regeneration. The aim of this study was to develop and optimize the production method of highly macroporous bone scaffold composed of polysaccharide matrix (chitosan–agarose) reinforced with nanohydroxyapatite. The highly macroporous structure was obtained by the simultaneous application of a gas-foaming agent and freeze-drying technique. Fabricated variants of biomaterials (produced using different gas-foaming agent and solvent concentrations) were subjected to porosity evaluation and compression test in order to select the scaffold with the best properties. Then, bioactivity, cytotoxicity, and cell growth on the surface of the selected biomaterial were assessed. The obtained results showed that the simultaneous application of gas-foaming and freeze-drying methods allows for the production of biomaterials characterized by high total and open porosity. It was proved that the best porosity is obtained when solvent (CH3COOH) and foaming agent (NaHCO3) are applied at ratio 1:1. Nevertheless, the high porosity of novel biomaterial decreases its mechanical strength as determined by compression test. Importantly, novel scaffold is non-toxic to osteoblasts and favors cell attachment and growth on its surface. All mentioned properties make the novel biomaterial a promising candidate to be used in regenerative medicine in non-load bearing implantation sites.

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.

scholarly journals Novel Selective IDO1 Inhibitors with Isoxazolo[5,4-d]pyrimidin-4(5H)-one Scaffold

2021 ◽  
Vol 14 (3) ◽  
pp. 265
Author(s):  
Ana Dolšak ◽  
Tomaž Bratkovič ◽  
Larisa Mlinarič ◽  
Eva Ogorevc ◽  
Urban Švajger ◽  
...  
Keyword(s):  
Systematic Investigation ◽  
The Novel ◽  
Indoleamine 2,3 Dioxygenase ◽  
Tryptophan Dioxygenase ◽  
Promising Target ◽  
Synthetic Procedure ◽  
Ic50 Values ◽  
Novel Scaffold ◽  
Further Development ◽  
Micromolar Range

Indoleamine 2,3-dioxygenase 1 (IDO1) is a promising target in immunomodulation of several pathological conditions, especially cancers. Here we present the synthesis of a series of IDO1 inhibitors with the novel isoxazolo[5,4-d]pyrimidin-4(5H)-one scaffold. A focused library was prepared using a 6- or 7-step synthetic procedure to allow a systematic investigation of the structure-activity relationships of the described scaffold. Chemistry-driven modifications lead us to the discovery of our best-in-class inhibitors possessing p-trifluoromethyl (23), p-cyclohexyl (32), or p-methoxycarbonyl (20, 39) substituted aniline moieties with IC50 values in the low micromolar range. In addition to hIDO1, compounds were tested for their inhibition of indoleamine 2,3-dioxygenase 2 and tryptophan dioxygenase, and found to be selective for hIDO1. Our results thus demonstrate a successful study on IDO1-selective isoxazolo[5,4-d]pyrimidin-4(5H)-one inhibitors, defining promising chemical probes with a novel scaffold for further development of potent small-molecule immunomodulators.

scholarly journals Microparticles, Microspheres, and Microcapsules for Advanced Drug Delivery

2019 ◽  
Vol 87 (3) ◽  
pp. 20 ◽  
Author(s):  
Miléna Lengyel ◽  
Nikolett Kállai-Szabó ◽  
Vince Antal ◽  
András József Laki ◽  
István Antal
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Freeze Drying ◽  
Delivery Systems ◽  
The Novel ◽  
Practical Applications ◽  
Inhaled Insulin ◽  
Formulation Factors ◽  
Novel Drug ◽  
Significant Production

Microparticles, microspheres, and microcapsules are widely used constituents of multiparticulate drug delivery systems, offering both therapeutic and technological advantages. Microparticles are generally in the 1–1000 µm size range, serve as multiunit drug delivery systems with well-defined physiological and pharmacokinetic benefits in order to improve the effectiveness, tolerability, and patient compliance. This paper reviews their evolution, significance, and formulation factors (excipients and procedures), as well as their most important practical applications (inhaled insulin, liposomal preparations). The article presents the most important structures of microparticles (microspheres, microcapsules, coated pellets, etc.), interpreted with microscopic images too. The most significant production processes (spray drying, extrusion, coacervation, freeze-drying, microfluidics), the drug release mechanisms, and the commonly used excipients, the characterization, and the novel drug delivery systems (microbubbles, microsponges), as well as the preparations used in therapy are discussed in detail.

scholarly journals Effect of Hot-Water Blanching Pretreatment on Drying Characteristics and Product Qualities for the Novel Integrated Freeze-Drying of Apple Slices

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hai-ou Wang ◽  
Qing-quan Fu ◽  
Shou-jiang Chen ◽  
Zhi-chao Hu ◽  
Huan-xiong Xie
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
Hot Water ◽  
The Novel ◽  
Rehydration Ratio ◽  
Drying Time ◽  
Drying Characteristics ◽  
Promising Alternative ◽  
Freeze Dried ◽  
Apple Slices

The effect of hot-water blanching (HWB) on drying characteristics and product qualities of dried apple slices with the novel integrated freeze-drying (NIFD) process was investigated by comparing with 3 different FD methods. Compared with the NIFD process without HWB pretreatment (VF-FD), the NIFD process with HWB pretreatment (HWB-VF-FD) resulted in a significantly higher mass loss and more sufficient freezing in vacuum-frozen samples, significantly higher rehydration ratio (RR), higher shrinkage ratio (SR), smaller Vitamin C (VC) content and lower hardness and better apparent shape in freeze-dried samples, and fewer change to the color of the dried or rehydrated samples (p<0.05). Compared with the conventional FD process with HWB pretreatment (HWB-PF-FD), HWB-VF-FD cost significantly less processing time and FD time and obtained significantly higher RR (p<0.05), almost the equivalent SR, VC content, and hardness, and similar appearance in dried samples. The microstructure of apple cell tissues was analyzed by transmission electron microscopy and scanning electron microscopy to interpret the above differences in drying characteristics and product qualities. The results suggested that the NIFD process of apple slices with HWB pretreatment was a promising alternative method to decrease drying time, achieve similar product quality, and simplify the process steps of the conventional FD technology.

scholarly journals Covid-19 Pandemic and its Politico-Economic Implications: A Study of Pakistan

2020 ◽  
Vol 4 (2) ◽  
pp. 42-51
Author(s):  
Misbah Shaheen ◽  
Uzma Siraj ◽  
Muhammad Nawaz Bhatti
Keyword(s):  
Health System ◽  
Mixed Method ◽  
Research Question ◽  
Political Stability ◽  
Mixed Method Research ◽  
The Novel ◽  
Simultaneous Application ◽  
Economic Implications ◽  
Substantial Decline ◽  
Comprehensive Framework

Pakistan is one among the countries terribly affected by the novel contagious disease named “COVID-19”. The severe economic shortfall caused by the pandemic is likely to worsen the already frangible situation of political stability. A country of over 220 million people with a fragile democracy, brittle health system, and the sinking economy is vulnerable to the drastic politico-economic implications of COVID-19. Hence, the present study aims to analyze the politico-economic implications of this on-going pandemic for Pakistan. Mixed-method research design has been employed to investigate the research question, as the only quantitative or qualitative analysis was not much appropriate to develop a better understanding of the problem investigated in the study. The simultaneous application of both the numerical and opinion-based data provided a comprehensive framework to reach logical findings. The study concludes that the inadequate health facilities and less coordinated response, along with a substantial decline in GDP, will make the post-pandemic scenario more challenging and cumbersome. The study suggests an integrated and coordinated approach to cope with this deadly phenomenon presently and to minimize the unfavourable implications in the future.

Use of Natural Biopolymers to Create Nanocomposite Materials

2020 ◽  
Vol 299 ◽  
pp. 299-304
Author(s):  
A.O. Makarova ◽  
L.R. Bogdanova ◽  
O.S. Zueva
Keyword(s):  
Carbon Nanotubes ◽  
Composite Materials ◽  
Sodium Alginate ◽  
Freeze Drying ◽  
Nanocomposite Materials ◽  
High Porosity ◽  
Composite Hydrogels ◽  
Xerogel Films

Method of carbon nanotubes disaggregation with the help of protein material, gelatin, has been proposed which facilitate to disperse evenly nanotubes in hydrogels based on gelatin and polysaccharides (sodium alginate or κ-carrageenan). In the obtained composite hydrogels carbon nanotubes are located in the biopolymer matrix, i.e. being in biocompatible form without losing their unique properties. The removal of water from the pores of the hydrogel by means of freeze drying allowed to obtain materials having high porosity and with included carbon nanotubes. The produced hydrogels can be used to create eco-friendly composite materials for biomedical and technical purposes. Depending on the tasks the developed systems can also be used in the forms of xerogel (films), cryogel, aerogel, and even in the form of powder, containing carbon nanotubes.

Freeze-drying preparation of porous diatomite ceramics with high porosity and low thermal conductivity

2020 ◽  
Vol 119 (4) ◽  
pp. 195-203
Author(s):  
Lei Han ◽  
Faliang Li ◽  
Haijun Zhang ◽  
Yuantao Pei ◽  
Longhao Dong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Freeze Drying ◽  
High Porosity ◽  
Low Thermal Conductivity

Biomineralization of Electrospun Nano-HA/PHB GTR Membrane

2007 ◽  
Vol 330-332 ◽  
pp. 695-698 ◽  
Author(s):  
Dong Hua Guan ◽  
Chun Peng Huang ◽  
Ji Liu ◽  
Kun Tian ◽  
Lin Niu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Electrospinning Process ◽  
Nanometer Scale ◽  
High Porosity ◽  
The Novel ◽  
Mineral Crystal ◽  
Novel Technology ◽  
Air Jet

Poly 3-hydroxybutyrate (PHB) as a kind of polysaccharides has been proved promising for tissue engineering because of its biocompatibility and biodegradability. But its poor mechanical properties and hydrophilicity limit its application. In order to explore a new useful porch to improve the performance of PHB-based GTR membrane, membrane composed of nano-HA / PHB composite was manufactured through the air/jet electrospinning process which can potentially generate nanometer scale diameter fibers and enlarge surface area of materials while maintaining high porosity. Successively, the biomineralization behavior of the membrane in supersaturated calcification solution (SCS) was studied. The Results of this investigation show that the successfully manufactured porous nano-HA/PHB membrane has high activity in SCS and its ability of inducing the formation of mineral crystal in vitro than that of the unfilled PHB membrane. It can be concluded that the addition of nano-HA and the novel technology could improve the performance of the PHB-based GTR membrane.

scholarly journals Anisotropic Cellulose Nanofibers/Polyvinyl Alcohol/Graphene Aerogels Fabricated by Directional Freeze-drying as Effective Oil Adsorbents

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 712 ◽  
Author(s):  
Lijie Zhou ◽  
Shengcheng Zhai ◽  
Yiming Chen ◽  
Zhaoyang Xu
Keyword(s):  
Polyvinyl Alcohol ◽  
Freeze Drying ◽  
High Efficiency ◽  
Cellulose Nanofibers ◽  
High Strength ◽  
Dip Coating ◽  
High Porosity ◽  
Water Contact ◽  
Water Separation ◽  
Composite Aerogel

Under the current situation of frequent oil spills, the development of green and recyclable high-efficiency oil-absorbing aerogel materials has attracted wide attention from researchers. In this study, we report a high-strength, three-dimensional hydrophobic cellulose nanofiber (CNF)/polyvinyl alcohol (PVA)/graphene oxide (GO) composite aerogel with an anisotropic porous structure, which was fabricated by directional freeze-drying technology using anisotropically grown ice crystals as a template, followed by hydrophobic treatment with a simple dip coating process. The prepared composite aerogel presented anisotropic multi-level pore microstructures, low density (17.95 mg/cm3) and high porosity (98.8%), good hydrophobicity (water contact angle of 142°) and great adsorption capacity (oil absorption reaching 96 times its own weight). More importantly, the oriented aerogel had high strength, whose compressive stress at 80% strain reached 0.22 MPa and could bear more than 22,123 times its own weight without deformation. Therefore, the CNF/PVA/GO composite aerogel prepared by a simple and easy-to-operate directional freeze-drying method is a promising absorbent for oil-water separation.

Novel authigenic gas foaming hydrogels for preventing coal spontaneous combustion

e-Polymers ◽  
2015 ◽  
Vol 15 (5) ◽  
pp. 361-368 ◽  
Author(s):  
Xiangming Hu ◽  
Weimin Cheng ◽  
Zhenlu Shao
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Acetic Acid ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Substantial Effect ◽  
Foaming Agent ◽  
Synchronous Thermal Analysis ◽  
Gas Foaming ◽  
Scanning Electron

AbstractAuthigenic gas foaming hydrogels were synthesized using chitosan (CS), acrylic acid, and attapulgite (APT) as hydrophilic monomers; potassium persulfate as initiator; N,N′-methylenebisacrylamide as cross-linker; and sodium carbonate (Na2CO3)/acetic acid as foaming agent. Effects of different monomers, amount of foaming agent, and temperature on swelling ratio (SR) of the hydrogels were examined. Morphology, structure, and thermal stability of authigenic gas foaming hydrogels were studied using field emission scanning electron microscope, Fourier-transform infrared spectroscopy, and synchronous thermal analysis. Scanning electron microscope images reveal apparent pores on hydrogels, produced by foaming agent Na2CO3/acetic acid. Therefore, more foaming agent would bring more pores on hydrogels. Synchronous thermal analysis results suggest that higher amount of CS would result in higher thermostability of hydrogels. However, APT has no substantial effect on thermal stability. SR decreases with increasing amount of CS. Hydrogels prepared at 70°C reaction temperature exhibit maximum swelling. Furthermore, SR decreases with higher covalence of saltion.

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