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Polymeric Biomaterials in Tissue Engineering
Published in Chander Prakash, Sunpreet Singh, J. Paulo Davim, Functional and Smart Materials, 2020
Akhilesh Kumar Maurya, Nidhi Mishra
Alginate is a naturally occurring anionic polymer of saccharide distributed widely in the class of Phaeophyceae, including Laminaria hyperborea, L. digitata, L. japonica, Ascophyllum nodosum, and Macrocystis pyrifera [42]. α-d-mannuronic acid and β-l-guluronic acid forms the structure of alginate that is derived from seaweed (Phaeophyceae) [43]. Ionic cross-linking in the presence of number of divalent cations, e.g., Ca2+, Mg2+, forms hydrogel of alginate [44]. Alginate has also been covalently cross-linked and oxidized in an attempt to optimize the physical properties of alginate hydrogel. ECMs of living tissues are structurally very similar, and this similarity allows it to be used in medical application such as wound healing, delivery of small chemical drugs and proteins and cell transplantation. Physiological moist in the microenvironment is maintained by the hydrogel of alginate at site wound and acts as a barrier for microorganisms infection at the site of wound and promotes wound healing [44,45]. (See Figure 2.5)
Recent advances in microbeads-based drug delivery system for achieving controlled drug release
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Zafar Khan, Mohammed A.S. Abourehab, Neha Parveen, Kanchan Kohli, Prashant Kesharwani
These are isolated from brown sea wood using a dilute alkaline solution which solubilizes the alginic acid present in alginates [44]. Alginic acid is made up of linear polymer of D-mannuronic acid and L-guluronic acid that are arranged as blocks in the polymeric chain. Alginic acid when reacts with sodium hydroxide gets converted into sodium alginate[45]. Naturally occurring alginate polymers possess several favorable properties like its accessibility, pH sensitive hydrogels forming capability and the lack of toxicity [46]. Sodium and calcium salts of alginic acid are considered as non-hazardous and biocompatible. Over 200 different grades are available commercially. A variety of impurities including heavy metals, proteins and endotoxins were present in alginates as they are naturally obtained [47]. For parenteral use these impurities should be removed. Ultrapure grades of alginates have low pyrogenicity and combination with other drugs as implants may be used [48].
Urban wastewater treatment by microalgae, bacteria and microalgae–bacteria system (Laboratory-scale study)
Published in Urban Water Journal, 2022
Masoud Noshadi, Rouhollah Nouripour
Alginate is a polysaccharide that extracted from brown algae and there are two compounds α-L-guluranicacid and β-D- mannuronicacid in their structures, which they are placed in the form of multi-polymer linear blocks. These blocks are different based on the size and presence of M, Mannuronic acid, or G, Guluronic acid. The ratio of M to G in alginates affects its viscosity. The greater values of this ratio indicate that the gel is softer and vice versa. This ratio and the overall structure of the alginate, however, depends on species of algae that alginate extracted from it. The sodium ions (Na+) exists in the structure of both compounds. In general, the monovalent cations simply replaced by two or more capacity cations. The tendency of cations for replacement is as follow:
Study on release of cardamom extract as an antibacterial agent from electrospun scaffold based on sodium alginate
Published in The Journal of The Textile Institute, 2021
Shima Najafi, Adeleh Gholipour-Kanani, Niloofar Eslahi, S. Hajir Bahrami
FTIR spectra of PVA, SA and SA:PVA nanofibers are indicated in Figure 4(A). As for sodium alginate, mannuronic acid and uronic acid functional groups can be seen at 884 cm−1 and 939 cm−1, respectively. The spectrum also shows O–H, CH2 stretching and C═O bonds at 3428 cm−1, 2928 cm−1, and 1625 cm1, respectively (Safi et al., 2007). PVA fibers show absorption bands at 3430 cm−1, 2941 cm−1, 1737 cm−1, 1098 cm−1, and 850 cm−1 (Guo et al., 2011), characteristics of the ν(OH), ν(CH2), ν(C═O), ν(C–O), and ν(C–C) resonances, respectively (Safi et al., 2007). In the blend electrospun SA:PVA nanofibers, the peaks of hydroxyl groups (O–H) of SA and PVA have shifted respectively from 3428 cm−1 and 3430 cm−1 to 3353 cm−1 due to formation of hydrogen bonds between hydroxyl groups of two polymeric components in the blend. The carboxyl peak of SA at 1625 cm−1 has also shifted to 1609 cm−1 in the blend which could be attributed to formation of hydrogen bonds between carboxyl groups of SA and hydrophilic groups of PVA. Safi et al. (2007) represented that hydrogen bonding could be formed between the oxygen atoms of ether groups of PEO (or the hydroxyl groups of PVA) and the hydroxyl groups of SA and even between the PVA chains that remained close together in the blended solution.