## 3 Functions of Dextran and Its Derivatives
### Dextran a Vehicle and Carrier for Drug Delivery  
Dextran and its modified derivatives have attracted immense interest from researchers in the design of delivery procedures for pharmaceuticals of clinical relevance. Several delivery systems based on dextran have evolved with desired configurations for intended capabilities. The fabrication strategies included self-assembled micelles and nanoparticles, nanoemulsions, magnetic nanoparticles, microparticles, and hydrogels for diverse applications [25]. In contrast to chemically synthesized molecules, natural materials, such as polysaccharides, have many advantages, including biodegradability, biocompatibility, and non-toxicity. These materials can be used for the protected encapsulation of different bioactive entities [26], which is crucial for the safer delivery of functional pharmaceutical components [27]. In recent years, the development of effective and safer delivery practices constructed from dextran has been explored with considerable benefits [28]. Delivery systems based on dextran EPS with purposely designed compositions, such as nanoparticles, nano-complexes, nano emulsions, nano-crystals and micelles, have been produced [27; 29; 30]. Dextran, as a biopolymer, offers certain benefits if it is used to build nanomaterials as a clinical vehicle for the delivery of important pharmaceuticals due to its exceptional solubility and non-immunogenicity. Dextran has characteristics of its solubility in a choice of solvents from H\({}_{2}\)O, dimethyl sulfoxide, ethylene glycol, or glycerol. This property is attached to the presence of \(\alpha\)-1, 6 glycosidic bond, which supports the expansion in the mobility of the polymer chain. Some drugs have poor aqueous solubility; hence, their dissolution in the gastrointestinal fluids is a slow process that affects the bioavailability of drug molecules [9; 31]. Dextran with high aqueous solubility is used in the fabrication of nanocarriers of drug molecules. It can facilitate the transportation of drugs and their effective bioavailability by permeation through the gastrointestinal membrane. The use of dextran in pharmaceutical delivery is preferred as it is a physiologically harmless biopolymer of saccharides and can, therefore, be metabolized by digestive enzymes. However, if synthetic polymers are used as vehicles, they might accrue in the system, causing side effects with their toxic degradation products [31]. The study was conducted to test subcutaneous implantation and tissue response evaluation; the results proposed in vivo biocompatibility of delivery systems based on dextran-polymer, as the dextran did not create a harmful or immunological effect on the body [32; 33]. Unlike other polysaccharides such as starch, dextran cannot be hydrolyzed by common amylase enzymes, for instance, amylase in saliva. This stability makes dextran a safer nanomaterial for its use in oral delivery systems. Its satisfactory colloidal stability towards the enzymatic degradation supports the reliability of the delivery vehicle through a prolonged retention duration in the system for increased bioavailability of the drug molecules. The dextran chain can only be depolymerized by the enzyme dextranase if available in the gastrointestinal tract and other organs [9]. Consequently, dextran-based drug delivery arrangements can be used to safeguard pharmaceutical compounds during their passage by increasing their absorption by the epithelium. The neutral charge of dextran facilitates the efficiency of drug delivery. [PERSON] et al. investigated nanoparticles with the capability of mucus-penetrating for drug and gene delivery to mucosal tissues. The intestinal mucus layer generated by the goblet cells is negatively charged and is capable of trapping nanocarriers with a hydrophobic nature in their surface properties [34]. However, if the vehicle was negatively charged, it would be difficult for it to traverse the mucus layer caused by the negative-negative repulsion.