Effect of pH and Freezing Condition on Cryogel Encapsulation of Curcumin

2015 ◽  
Vol 1103 ◽  
pp. 9-14
Author(s):  
Nataporn Sowasod ◽  
Kyuya Nakagawa ◽  
Tawatchai Charinpanitkul ◽  
Wiwut Tanthapanichakoon
Keyword(s):  
Controlled Release ◽  
Pore Size ◽  
Cooling Rate ◽  
Colloidal Suspension ◽  
Alkaline Media ◽  
Freeze Dried ◽  
Microstructural Morphology ◽  
Freezing Condition ◽  
Rate Type

The aim of this study was to develop a pH-sensitive ternary system of chitosan, κ-carrageenan, and carboxymethylcellulose sodium salt (CMC) that can serve as a controlled release system. Encapsulation of curcumin in chitosan was achieved by transforming the present colloidal suspension into hydrogels via cryotropic gel formation. The frozen hydrogel specimens (cryogels) were freeze-dried for preservation and investigation. It was reported that, when the ratio of κ-carrageenan to NaCMC was kept constant, the cooling rate was found to determine the type of release between burst type and controlled first-order-rate type [1]. The microstructural morphology of freeze-dried specimens was observed with a Scanning Electron Microscope (SEM) to be affected by the cooling rate. The faster cooling rate produced specimens with slightly larger pore size and, as a result, higher amount of curcumin released at 2 days. Swelling tests of the hydrogels in buffer solutions of different pH values showed that acidic media had a pronounced effect on swelling compared to the neutral and alkaline media. The faster cooling rate produced specimens that had higher structural strength against swelling despite the fact that the specimens had larger pore size and faster controlled release rate.

Pectin-Chitosan Multilayer Coated Microbeads of Diclofenac Sodium Prepared by Layer-by-Layer Technique

2014 ◽  
Vol 1060 ◽  
pp. 45-49
Author(s):  
Kamonrak Cheewatanakornkool ◽  
Pornsak Sriamornsak
Keyword(s):  
Controlled Release ◽  
Drug Release ◽  
Diclofenac Sodium ◽  
Gastric Fluid ◽  
Layer By Layer ◽  
Release Behavior ◽  
Freeze Dried ◽  
Layer Technique ◽  
Calcium Pectinate ◽  
Layer By Layer Technique

The main objective of this study was to fabricate biopolymer-based microbeads, providing enteric properties and controlled release of diclofenac sodium, using layer-by-layer technique. The calcium pectinate microbeads have been designed and coated with chitosan and pectin multilayers. Drug release was performed in simulate gastric fluid (pH 1.2) for 2 hours, followed by pH 6.8 buffer for 8 hours. The effects of chitosan concentration, number of layer and drying technique on drug release were investigated. The results showed that the calcium pectinate microbeads could be simply prepared by ionotropic gelation and then coated with chitosan and pectin solutions using layer-by-layer procedure. The diameter of the microbeads ranged from 800 to 1000 μm for air-dried samples and from 1 to 2 mm for freeze-dried samples. The freeze-dried microbeads had a rough surface and many pores inside, as observed by SEM. The microbeads coated with 4% chitosan/4% pectin revealed a slower drug release than those coated with 1% chitosan/4% pectin and demonstrated a controlled release pattern. Moreover, different drying techniques and numbers of layer also influenced drug release behavior of the prepared microbeads.

scholarly journals Experimental investigation on pore size distribution and drying kinetics during lyophilization of sugar solutions

2018 ◽  
Author(s):  
Petra Foerst ◽  
M. Lechner ◽  
N. Vorhauer ◽  
H. Schuchmann ◽  
E. Tsotsas
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Freeze Drying ◽  
Three Dimensional ◽  
Drying Kinetics ◽  
Process Efficiency ◽  
Freeze Dried ◽  
Pore Size Distributions

The pore structure is a decisive factor for the process efficiency and product quality of freeze dried products. In this work the two-dimensional ice crystal structure was investigated for maltodextrin solutions with different concentrations by a freeze drying microscope. The resulting drying kinetics was investigated for different pore structures. Additionally the three-dimensional pore structure of the freeze dried samples was measured by µ-computed tomography and the pore size distribution was quantified by image analysis techniques. The two- and three-dimensional pore size distributions were compared and linked to the drying kinetics.Keywords: pore size distribution; freeze drying; maltodextrin solution; freeze drying microscope   

scholarly journals The effect of substrate pore size on the differentiation of L929 fibroblast cells: Morphological observations and expression of type 1 collagen mRNA

2004 ◽  
Vol 25 (2) ◽  
pp. 61-68 ◽  
Author(s):  
Tatsuo SHIIGAI ◽  
Masaki SHIMONO ◽  
Masao YOSHINARI ◽  
Kenichi MATSUZAKA ◽  
Takashi INOUE
Keyword(s):  
Pore Size ◽  
Fibroblast Cells ◽  
Collagen Mrna ◽  
L929 Fibroblast

scholarly journals Biologically active collagen-based scaffolds: advances in processing and characterization

2010 ◽  
Vol 368 (1917) ◽  
pp. 2123-2139 ◽  
Author(s):  
I. V. Yannas ◽  
D. S. Tzeranis ◽  
B. A. Harley ◽  
P. T. C. So
Keyword(s):  
Biological Activity ◽  
Pore Size ◽  
Type I Collagen ◽  
Biologically Active ◽  
Wound Contraction ◽  
Type I ◽  
Structural Determinants ◽  
Ligand Density ◽  
Freeze Dried ◽  
Recent Developments

A small number of type I collagen–glycosaminoglycan scaffolds (collagen–GAG scaffolds; CGSs) have unusual biological activity consisting primarily in inducing partial regeneration of organs in the adult mammal. Two of these are currently in use in a variety of clinical settings. CGSs appear to induce regeneration by blocking the adult healing response, following trauma, consisting of wound contraction and scar formation. Several structural determinants of biological activity have been identified, including ligands for binding of fibroblasts to the collagen surface, the mean pore size (which affects ligand density) and the degradation rate (which affects the duration of the wound contraction-blocking activity by the scaffold). Processing variables that affect these determinants include the kinetics of swelling of collagen fibres in acetic acid, freezing of the collagen–GAG suspension and cross-linking of the freeze-dried scaffold. Recent developments in the processing of CGSs include fabrication of scaffolds that are paucidisperse in pore size, scaffolds with gradients in physicochemical properties (and therefore biological activity) and scaffolds that incorporate a mineral component. Advances in the characterization of the pore structure of CGSs have been made using confocal and nonlinear optical microscopy (NLOM). The mechanical behaviour of CGSs, as well as the resistance to degradative enzymes, have been studied. Following seeding with cells (typically fibroblasts), contractile forces in the range 26–450 nN per cell are generated by the cells, leading to buckling of scaffold struts. Ongoing studies of cell-seeded CGSs with NLOM have shown an advantage over the use of confocal microscopy due to the ability of the former method to image the CGS surfaces without staining (which alters its surface ligands), reduced cell photodamage, reduced fluorophore photobleaching and the ability to image deeper inside the scaffold.

Influence of Environmental Humidity on Wear Behavior of Aluminum Alloy Impregnated Graphite Composite Under Insufficient Lubrication

2007 ◽  
Author(s):  
Hozumi Goto ◽  
Yusaku Shibuya
Keyword(s):  
Wear Behavior ◽  
High Rate ◽  
Lubricating Oil ◽  
Dry Sliding ◽  
Graphite Composite ◽  
Wear Mode ◽  
Type 3 ◽  
Rate Type

Wear characteristics of an Al-Si alloy impregnated graphite composite containing 56 vol% graphite and its matrices in contact with bearing steel were investigated under insufficient lubrication. Pin-on-disk type wear tests in air were conducted at various levels of relative humidity (RH) under dry sliding and drip feed lubrication (0.005 to 0.02 cm3) before each test by using base oil for engines. Changes in friction and wear were continuously monitored during the tests. Four types of wear mode for the composite were obtained: steady wear with a low rate (Type 1), high wear after a lubricating oil shortage (Type 2), no wear after pin lifting (Type 3) and steady wear with a high rate (Type 4). Type 1 appears over the whole range of RH (5 to 80%). Type 2 is found at low RH levels of 5 and 10%. Type 3 occurs at a frequency of 30 percents between 10 and 35% RH. Type 4 is seen over the whole RH range under dry sliding. The appearance of each wear mode at a specified RH depends on wear behavior of the matrices associated with RH under drip feed lubrication.

scholarly journals Radiation-crosslinked scaffolds from gelatin/CM-chitin and gelatin/CM-chitosan hydrogels for adipose-derived stem cell culture

2021 ◽  
Vol 10 (3) ◽  
pp. 13-21
Author(s):  
Dang Van Phu ◽  
Nguyen Quoc Hien ◽  
Le Anh Quoc ◽  
Nguyen Ngoc Duy ◽  
Phan Phuoc Thang ◽  
...  
Keyword(s):  
Pore Size ◽  
Soft Tissues ◽  
Gamma Ray ◽  
Radiation Technology ◽  
Freeze Dried ◽  
Swelling Capacity ◽  
Radiation Crosslinking ◽  
Soft Tissue Engineering ◽  
Chitosan Hydrogels ◽  
Adipose Derived Stem Cell

Radiation technology has been providing a useful tool to modify polymers involving the radiation crosslinking of hydrogels. In the present work, two kinds of hydrogels composed gelatin and carboxymethyl chitosan (gelatin/CM-chitosan), and carboxymethyl chitin (gelatin/CM-chitin) were prepared by the radiation crosslinking. The resulting hydrogels were freeze-dried, sterilized under gamma-ray at a sterilization dose of 25 kGy, and characterized to be utilized as the scaffolds for culturing adipose-derived stem cells (hADSCs). The physicochemical properties, biodegradability, and cytotoxicity of these scaffolds were also investigated. The results indicated that both CM-chitosan and CM-chitin much improved the swelling capacity, porosity, and pore size of the gelatin-derived scaffolds. The swelling degree of gelatin/CM-chitosan and gelatin/CM-chitin scaffolds was about 7-9 g/g after 6 hrs immerging in PBS, and their porosity was about 70-73% with pore size ranging from 100 to 300 mm. The results also revealed that the compressive modulus of gelatin/CM-chitosan and gelatin/CM-chitin was 45.6 and 66.4 kPa, respectively, which were suitable for soft tissue engineering. Both scaffolds were enzymatically biodegradable by collagenase and non-cytotoxic for hADSCs with an RGR of ~97%. Thus, the resultant scaffolds can be suitably utilized for culturing hADSC in practice to regenerate soft tissues.

scholarly journals Study of Bifidobacterium Lactic 300b Survival during Encapsulation, Coating and Freeze Drying Process and the Release in Alkaline Media

2012 ◽  
Vol 69 (2) ◽  
Author(s):  
Oana Lelia POP ◽  
Thorsten BRANDAU ◽  
Dan Cristian VODNAR ◽  
Carmen SOCACIU
Keyword(s):  
Freeze Drying ◽  
Dip Coating ◽  
Alkaline Media ◽  
Drying Process ◽  
Bifidobacterium Lactis ◽  
Coating Application ◽  
Encapsulated Cells ◽  
Beneficial Effects ◽  
Freeze Dried ◽  
Coating Method

The survival of probiotics is of paramount importance because to have their beneficial effects on the host’s health, they must stay alive up to the site of their action. It is known that the resistance of probiotic cells in acidic media, as in the stomach, is very low, that’s why the encapsulation of Bifidobacterium lactis 300B in alginate matrices is needed. This study present the mechanism of cell survival during encapsulation, coating and freeze drying process and release in simulated intestinal media. Microspheres with mean diameter 1100 µm and 66.87% encapsulation rate were obtained and described. In order to increase the protection of Bifidobacterium lactis 300B in the alginate/pullulan based microspheres, three types of dip coating were proposed. Namely, the alginate microspheres were coated in alginate, chitosan or gelatin, using the dip coating method by crosslinking. The survival of the cells was tested after encapsulation, coating application and compared with free and encapsulated cells, using the plate counting method. Also, the survivability in freeze dried microspheres was tested. Although the coated microspheres showed higher survivability compared with free and encapsulated cells, the release in alkaline pH was no possible for the gelatin coated alginate/pullulan based microspheres. 

Preparation of Microencapsulated Symbiotic Complex of Probiotics based on Lactobacillus helveticus using Alginate and Chitosan

2020 ◽  
Vol 36 (2) ◽  
pp. 56-63
Author(s):  
D.K. Toropov ◽  
T.S. Egorova
Keyword(s):  
Biological Activity ◽  
Gastrointestinal Tract ◽  
Controlled Release ◽  
Bacterial Colonization ◽  
Lactobacillus Helveticus ◽  
Aggressive Environment ◽  
Aggressive Action ◽  
Freeze Dried ◽  
Complex Equipment ◽  
Extrusion Method

Various technologies for producing different forms of probiotic preparations including Vitaflor have been compared. This preparation was created based on two symbiotic Lactobacillus helveticus strains, D-75 and D-76, with proven effects of syntrophy and synergism. It is produced in the form of freeze-dried lactobacilli biomass. It was shown that the biological activity of Vitaflor in an aggressive environment of the gastrointestinal tract (GET) was reduced to a level that excluded both bacterial colonization and therapeutic effect. Alginate-chitosan microcapsules containing the Vitaflor symbiotic complex protected the microorganisms from the aggressive action of the GET medium and provided their time-controlled release. The emulsion encapsulation turned out to be most effective: the protection of live lactobacilli was 5 orders of magnitude higher than that in the Vitaflor preparation and 3 orders of magnitude higher than with the extrusion method of obtaining microcapsules. The emulsion encapsulation developed for Vitaflor can be applied to other microorganisms; the technique is rather simple, easily scalable and does not require complex equipment. probiotics, Lactobacillus helveticus, microencapsulation technology, natural polysaccharides, alginate, chitosan

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