## 2 Description of Dextran Polysaccharide
### Clinical Derivatives from Dextran  
Dextran has been considered a multifunctional biopolymer starting material for designing varied molecular configurations that are suitable for wide-ranging applications. Its molecular weight range with substantial availability of active hydroxyl groups in the polymer chain are favorable characteristics for dextran's modifications. Since dextran is a neutral material, it has been illustrated as a promising macromolecular vehicle and carrier for drug chemicals [12]. Hence, numerous glycol-conjugates have been prepared as derivatives of dextran in suitable reactions selected for the required product, such as a relevant process of oxidation, esterification, or etherification [13].  
[PERSON] et al. reported the effect of the reaction of esterification on structural, physico-chemical, and flocculation characteristics of dextran, which could be useful in different applications. Researchers suggested that esters of dextran can be prepared by adding an alkaline amino acid, lysine, onto the dextran polymer chain [14]. Dextran-ester demonstrated remarkable flocculation characteristics at low pH, caused by its extended polymer chain with amino groups, which can interact with substances having points with negative charges. In a different study conducted by [PERSON] et al., a long-chain fatty ester of dextran was prepared through in situ activation of carboxylic acid using iminium chloride [15]. Meltable dextran esters with significant melting behavior and biocompatibility are good functional coating materials. The dextran esters have the ability to form durable layers of films on several materials, for instance, glass and nitrided titanium implants, to facilitate the prevention of persistent inflammatory stimulus. This ester as a dextran derivative extends applications of a useful polysaccharide in the biomedical sciences. Dextran has also been applied in the spray-drying method of preparing powders that are used for the encapsulation of drugs and additives used in the pharmaceutical and food industries [11].  
Dextran is a bacterial polysaccharide that has exceptional biodegradability, biocompatibility, and non-toxicity characteristics. Dextran molecules meet critical requirements of nanomaterials for their applications in pharmaceutics. Therefore, distinct derivatives of dextran have been developed through its modification because of the presence of a substantial number of reactive hydroxyl groups in its chain [12; 13]. Unique delivery systems based on dextran, for example, micelles, magnetic nanoparticles, mini emulsions, hydrogels, and spray-dried powders, have been the subject of research and development. Their physicochemical properties, release mechanisms, and therapeutic effects performed in in vivo animal experiments have been studied in detail to establish their extensive applications in medicine and formulations of pharmaceutical compounds. [PERSON] et al. have testified that the use of amphipathic prodrug micelles of dextran-doxorubicin is suitable for the treatment of solid tumors [16]. Table 1 presents some of the useful dextran derivatives.  
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