**9. Antioxidant-Polysaccharides Graft Polymers**

Polysaccharide graft polymers play an integral role in biomedical (targeted drug delivery systems) and commercial engineering applications given their unique properties and wide range of sources (microbial and natural). In contrast to other precursors, polysaccharides are cheap and widely available [105]. Moreover, the materials have comparable properties as antioxidant terpene polymers in terms of biodegradation ability, water solubility, and non-toxicity. Grafted polysaccharides have attracted significant research attention based on a broad scope of application, chemical stability, efficiency, biocompatibility, tailored properties, and biodegradation ability. Recent advances in drug delivery research have demonstrated that the rate of in vivo drug delivery could be predicted by the extent of crosslinking and grafting [105]. The enhanced functionality is linked to chemical bonding between the grafted polymer chains and polymeric substrate. The free radicals are introduced onto the backbone structure through irradiation and chemical initiation.

Despite the promising material prospects, the polysaccharide graft polymers have not conclusively addressed challenges associated with traditional drug delivery systems, such as sustaining the desired drug dosage in tissues for an extended period (length of treatment). However, there are promising prospects that the uncontrolled drug release kinetics would be resolved through better absorption rates [105]. The progress made in targeted drug delivery by Pal and Das [105] is in line with Lemarchand et al. [106] research on polyester-polysaccharide nanoparticles for drug delivery systems. In particular, the nanoparticles graft polymers from poly (D, L-lactide) or poly(ε–caprolactone) (PCL) demonstrated ideal pharmacokinetic behavior linked to the synthesis route—emulsion solvent evaporation. The material exhibited superior stability with or without emulsions, and strong amphiphilic properties, which eliminated the need for surfactants.

The emulsion solvent evaporation technique's ability to influence the targeted drug delivery is comparable to RAFT (reversible addition-fragmentation chain transfer polymerization), reversible deactivation radical polymerization, and atom transfer radical polymerization; these two procedures were employed by Garcia-Valdez in the modification of polysaccharides to attain ideal control over the molecular weight distribution, and carefully control the macromolecular shapes, and sizes [107]. From an engineering perspective, the experimental outcomes reported following the adoption of different synthetic routes introduce unique challenges because the outcomes were based on laboratory-scale models; there are concerns that the procedures could lead to different outcomes in large experiments. The highlighted concerns could be resolved through advances in synthesis technologies, including lab-on-a-chip.
