**3.2 Oral inorganic NP**

Inorganic NP represent a wide spectrum of systems synthesized from metals, metal oxides, and metal sulphides [65]. Gold, silica and superparamagnetic oxide NP are among the long list of inorganic NP (**Figure 3**). They have been studied for

#### **Figure 2.**

*Examples of organic nanoparticle platforms for drug delivery.*

**Figure 3.**

*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 toxic [68].

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

**35**

*Gastrointestinal Delivery of APIs from Chitosan Nanoparticles*

capabilities compared with their colloidal counterparts [14, 69].

water-soluble drugs; useful in drug targeting in the GIT [76].

acetic acid and formic acid, due to protonated amine groups (NH3+

D-glucosamine and N-acetylated units (**Figure 4**).

delivery system and forms part of the evolutional success in several clinical applications. Polymeric NP arguably presents more desirable attributes as orally delivered NP because of their higher stability, enhanced drug payload and controlled drug release

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

Chitosan is a hydrophilic, cationic polysaccharide soluble in dilute acids such as

The amine group has pKa of 6.2–6.5 [78]. At slightly acidic pH values, the amine

electrostatic interactions with negatively charged species within mucin in the GIT [75]. Positively charged moieties of chitosan also interact with the tight junctions of the intestinal epithelial cells and thus modulate drug permeation and absorption through the interstitial space between epithelial cells [79]. Moreover, the existence of both hydroxyl and amino groups offers various possibilities for chemical modification. Chemical modifications give rise to different functional derivatives of chitosan like carboxylation, thiolation, alkylation, acylation etc. that further imparts desirable physiochemical and biopharmaceutical properties, such as solubility, adsorption and pH sensitivity in oral drug delivery [80]. For example, N-trimethyl chitosan chloride is developed to amplify the intestinal solubility of chitosan; thiolated chitosan is produced to augment the mucoadhesiveness of chitosan;

) become protonated, hence possessing the ability to effectively form

N-acetylated derivative of chitin, a natural polysaccharide found in the shells of marine crustaceans. Chitin is chemically inert and thus has fewer applications that chitosan [77]. The acetamido group of chitin, (C2H4NO) can be turned into amino group to yield chitosan by the alkaline deacetylation of chitin. Chitosan is approved as safe by the United States Food and Drug Administration (US-FDA) for dietary use and wound dressing applications, but its toxicity increases with electrical charge and degree of deacetylation [17]. Chemically, it comprises of β- [1–4] -linked

) [75]. It is an

*DOI: http://dx.doi.org/10.5772/intechopen.95363*

**3.3 Polymeric NP**

**4. Chitosan polymer**

groups (NH3+

delivery system and forms part of the evolutional success in several clinical applications. Polymeric NP arguably presents more desirable attributes as orally delivered NP because of their higher stability, enhanced drug payload and controlled drug release capabilities compared with their colloidal counterparts [14, 69].
