Microencapsulation of retinoic acid by atomization into biopolymeric matrices: Binary and ternary blends of alginic acid sodium, xanthan gum and modified chitosan

2021 ◽  
pp. 107310
Author(s):  
Antónia Gonçalves ◽  
Berta N. Estevinho ◽  
Fernando Rocha
Keyword(s):  
Retinoic Acid ◽  
Xanthan Gum ◽  
Alginic Acid ◽  
Ternary Blends ◽  
Modified Chitosan

Some chemical and analytical aspects of polysaccharide modifications. I. Nitroxide spin-labelling studies of alginic acid, cellulose, and xanthan gum

1981 ◽  
Vol 59 (21) ◽  
pp. 3105-3119 ◽  
Author(s):  
Mansur Yalpani ◽  
Laurance D. Hall
Keyword(s):  
Xanthan Gum ◽  
Alginic Acid ◽  
Periodate Oxidation ◽  
Cyclic Carbonate ◽  
Spin Labels ◽  
Hydroxyl Groups ◽  
Direct Reaction ◽  
Spectroscopic Techniques ◽  
Sodium Cyanoborohydride ◽  
Polysaccharide Derivatives

Nitroxide spin labels have been employed as model reagents for evaluating several aspects of the synthesis of covalently modified polysaccharide derivatives using alginic acid 1, xanthan gum 19, and cellulose 23 as exemplars. Modifications were accomplished both nonspecifically, by the alkylation of hydroxyl groups, and specifically, either by direct transformation of the carboxylate function of 1 and 19 or after introduction of appropriate prominent functions, such as aldehydes or amines. Thus, the acetamido ether 3 was obtained from 1 and chloroacetamide 2. The carboxylate functions of 1 and 19 were condensed with amines to yield the corresponding amides 8, 10, 20, 21, and 22 either by direct reaction, by carbodiimide-mediated coupling, or by transesterification. The amine derivatives 12,13, 25, and 18 were obtained either from dialdehyde derivatives via periodate oxidation or from s-triazine intermediates, using sodium cyanoborohydride. Similarly, the keto spin label 15 reacted with hydrazide intermediates 14 and 29 in the presence of sodium cyanoborohydride to afford the hydrazide derivatives 16 and 30. The cellulose urethane derivative 27 was obtained via the cyclic carbonate precursor. The products were characterized by esr and other spectroscopic techniques.

scholarly journals Fabrication and Characterization of Xanthan Gum-cl-Poly(Acrylamide-co-Alginic Acid) Hydrogel for Adsorption of Cadmium Ions from Aqueous Medium

Gels ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 23
Author(s):  
Gaurav Sharma ◽  
Amit Kumar ◽  
Ayman A. Ghfar ◽  
Alberto García-Peñas ◽  
Mu. Naushad ◽  
...  
Keyword(s):  
Contact Time ◽  
Xanthan Gum ◽  
Alginic Acid ◽  
Freundlich Isotherm ◽  
Aqueous System ◽  
Significant Loss ◽  
Batch Adsorption ◽  
Facile Fabrication ◽  
Poly Acrylamide

The present research demonstrates the facile fabrication of xanthan gum-cl-poly(acrylamide-co-alginic acid) (XG-cl-poly(AAm-co-AA)) hydrogel by employing microwave-assisted copolymerization. Simultaneous copolymerization of acrylamide (AAm) and alginic acid (AA) onto xanthan gum (XG) was carried out. Different samples were fabricated by changing the concentrations of AAm and AA. A sample with maximum swelling percentage was chosen for adsorption experiments. The structural and functional characteristics of synthesized hydrogel were elucidated using diverse characterization tools. Adsorption performance of XG-cl-poly(AAm-co-AA) hydrogel was investigated for the removal of noxious cadmium (Cd(II)) ions using batch adsorption from the aqueous system, various reaction parameters optimized include pH, contact time, temperature, and concentration of Cd(II) ions and temperature. The maximum adsorption was achieved at optimal pH 7, contact time 180 min, temperature 35 °C and cadmium ion centration of 10 mg·L−1. The XG-cl-poly(AAm-co-AA) hydrogel unveiled a very high adsorption potential, and its adsorption capacities considered based on the Langmuir isotherm for Cd(II) ions was 125 mg·g−1 at 35 °C. The Cd(II) ions adsorption data fitted nicely to the Freundlich isotherm and pseudo-first-order model. The reusability investigation demonstrated that hydrogel retained its adsorption capacity even after several uses without significant loss.

Morphological behavior of compatibilized ternary blends prepared by mechanical mixing

1993 ◽  
Vol 51 ◽  
pp. 1200-1201
Author(s):  
S.D. Smith ◽  
R.J. Spontak ◽  
D.H. Melik ◽  
S.M. Buehler ◽  
K.M. Kerr ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Diblock Copolymers ◽  
Ternary Blends ◽  
Mechanical Mixing ◽  
Design Considerations ◽  
Covalently Bonded ◽  
Homopolymer Blends ◽  
Emulsifying Agent ◽  
Surface Active ◽  
Low Entropy

When blended together, homopolymers A and B will normally macrophase-separate into relatively large (≫1 μm) A-rich and B-rich phases, between which exists poor interfacial adhesion, due to a low entropy of mixing. The size scale of phase separation in such a blend can be reduced, and the extent of interfacial A-B contact and entanglement enhanced, via addition of an emulsifying agent such as an AB diblock copolymer. Diblock copolymers consist of a long sequence of A monomers covalently bonded to a long sequence of B monomers. These materials are surface-active and decrease interfacial tension between immiscible phases much in the same way as do small-molecule surfactants. Previous studies have clearly demonstrated the utility of block copolymers in compatibilizing homopolymer blends and enhancing blend properties such as fracture toughness. It is now recognized that optimization of emulsified ternary blends relies upon design considerations such as sufficient block penetration into a macrophase (to avoid block slip) and prevention of a copolymer multilayer at the A-B interface (to avoid intralayer failure).

Effects of Retinoic Acid and 1,25-Dihydroxyvitamin D3 on IFN-gamma Secretion by Mononuclear Leukocytes from Nulliparous and Postparturient Dairy Cattle

2000 ◽  
Vol 70 (3) ◽  
pp. 92-101 ◽  
Author(s):  
Burim Ametaj ◽  
Brian Nonnecke ◽  
Ronald Horst ◽  
Donald Beitz
Keyword(s):  
Retinoic Acid ◽  
Dairy Cattle ◽  
Dairy Cows ◽  
Dairy Cow ◽  
Pokeweed Mitogen ◽  
Mononuclear Leukocytes ◽  
Combined Effects ◽  
Ifn Gamma ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D

Individual and combined effects of several isomers of retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on interferon-gamma (IFN-gamma) secretion by blood mononuclear leukocytes (MNL) from nulliparous and postparturient Holstein cattle were evaluated in vitro. In the first experiment, effects on incubation period (24 to 72 hours) and time of supplementation (0 to 32 hours) with all-trans, 9-cis, 13-cis-, and 9,13-dicis-RAs (0 to 100 nM) on IFN-gamma secretion by pokeweed mitogen (PWM)-stimulated (0 and 10 mug/ml) MNL from nulliparous cattle were evaluated. In the second experiment, MNL from postparturient cows (bled at 0, 2, 4, and 16 days postpartum) were stimulated with PWM (0 and 10 mug/ml) in the presence of RA isomers (9-cis- or 9,13-dicis-RA; 0 to 100 nM), 1,25-(OH)2D3 (0 to 100 nM), or with combinations of these metabolites. The results show that individual isomers of RA had no effect on IFN-gamma secretion by PWM-stimulated MNL from nulliparous or postparturient cows. Furthermore 1,25-dihydroxyvitamin D3 inhibited IFN-gamma secretion by MNL from nulliparous and postparturient dairy cows; however, the degree of inhibition was greater when 9-cis- and 9,13-dicis-RA were also present in the cultures. Finally mononuclear leukocytes from postparturient dairy cows produced substantially less IFN-gamma than did MNL from nulliparous cattle. It is concluded that retinoic acids individually did not affect the capacity of leukocytes from dairy cattle to secrete IFN-gamma. This result is in marked contrast to studies in monogastric species indicating that RAs inhibit IFN-gamma secretion by peripheral blood T cells. Inhibition of IFN-gamma secretion by 1,25-(OH)2D3 was potentiated by 9-cis- and 9,13-di-cis-retinoics acids, suggesting that an excess of dietary vitamins A and D may compromise further the naturally immunosuppressed postparturient dairy cow. Additional research is necessary to determine if the combined effects of these metabolites on IFN-gamma secretion represent an increased susceptibility of the dairy cow to infectious diseases during the periparturient period. Lower secretion of IFN-gamma by MNL from postpartutient dairy cows, relative to nulliparous cattle, suggests that recently-calved cows are naturally immunosuppressed.

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