**3.3 Polymeric NP**

*Chitin and Chitosan - Physicochemical Properties and Industrial Applications*

*Examples of organic nanoparticle platforms for drug delivery.*

*Examples of inorganic NP platforms for drug delivery.*

use in imaging on nuclear magnetic resonance and high-resolution superconducting quantum interference devices, and their intrinsic properties have been utilised for therapy [66]. Inorganic NP can easily be conjugated to ligands for tumour targeting and/or with chemotherapeutics for tumour therapy. Additionally, their surface composition can be feasibly manipulated to create NP that can escape the reticuloendothelial system [67]. Even though inorganic NP present good stability characteristics, they have not been the focus of attention in oral NP research, possibly due to concerns on the degradation and elimination end products, which can be potentially

Generally, inorganic NPs differ conceptually from organic NPs in terms of fabrication principles. Inorganic NPs can be formed by the precipitation of inorganic salts, which are linked within a matrix, whilst, most organic NPs are formed by several organic molecules through self-organization or chemical binding [61]. Notwithstanding, both types of NP are very promising in the formulation of oral

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toxic [68].

**Figure 3.**

**Figure 2.**

According to Alexis F. et al., polymeric NP represent the most effective nanocarrier system for prolonged drug delivery [70]. 'Polymeric NPs' include any type of polymer formed as NP. Nanospheres are solid spherical NP with molecules attached or adsorbed to their surface, whilst nanocapsules are vesicular systems with substances confined within a cavity consisting of a liquid core (either water or oil) surrounded by a solid shell [71]. Characteristic properties of polymers such as molecular weight, hydrophobicity and crystallinity can be explored to manifest controlled drug release kinetics and entrapment of therapeutic agents [72]. Polymers also provide significant flexibility in the design of oral NP and many exhibit biodegradability [73]. In this regard, synthetic and natural variants have been studied. For example poly-lactic-co-glycolic-acid (PLGA) and poly-lactic-acid (PLA) are synthetic whilst natural polymers include gelatine, dextran, and chitosan [74]. The use of natural polymers is preferred over the synthetic ones as the former usually exhibit less toxicity, widely available and have lower production costs [75]. Chitosan is arguable one of the most studied polymer in NP formulation in view of its distinctive properties. In orally administered NP, chitosan offers added desirability including muco-adhesiveness, augmenting the dissolution rate of poorly water-soluble drugs; useful in drug targeting in the GIT [76].
