**2.11. The latest MMT pattern used in drug delivery systems**

Lin et al. showed the 5-FU interference on the MMT inner layers [61]. 5-FU-MMT was determined and the successful interference of the drug in MMT was confirmed by opening the inner layer and changing the XRD pattern to the lower 2θ angle, and the results are presented in **Figure 9**. Finally, it can be concluded that the total amount of 5-FU absorbed in MMT is approximately 87.5 mg/g MMT.

Park et al. reported the placement of donepezil molecules on clay (Laponite, LA, saponite, SA and MMT) and provided descriptive information, which confirmed the well-located donepezil molecules in the inner layers of clay (**Figure 10**) [91]. The absorption amount and the donepezil molecular structure depend on the cationic exchange ability of clay, which has designed drug release patterns. The rate of release can be increased easily by using a large cationic polymer. The Eudragit® E-100 hybrid, coated with such a polymer, shows the release of drug at higher speeds over a short period. Therefore, nanoclay materials are proposed as an advanced carrier for drug delivery with a controllable release feature.

**Figure 8.** Mechanism of drug release from nanocomposites [106].

material in solution. In biological fluids, "anti-ions" can move the drug into the substrate and transfer it to the body, so the converter can be removed or decomposed at the end (**Figure 7**) [106]. Smectites, especially MMT and saponite, have been further studied due to their ionic exchange capacity compared to other silicates (talc, kaolin, and fibrous mineral clay). A specific mechanism depends on factors such as functional groups and chemical physical properties

**Figure 7.** Mechanism of release of MMT and absorption in the body [106].

**Figure 6.** The number of studies on the use of clay nanoparticles as carrier for drug delivery [106].

176 Current Topics in the Utilization of Clay in Industrial and Medical Applications

pancreatic cancer cells, gastric cancer, prostate cancer, breast cancer, esophageal cancer, and thyroid cancer diagnosis. However, lung cancer and leukemia require structural harder compounds for drug delivery. DOX-Kaolin and its internal contents exhibit more drug release rates in acidic environment than in the neutral environment. The use of two-dimensional clay nanoparticles for a drug delivery system can pave the way for high-performance nanotherapies with superior antitumor efficacy and significant reduction of side effects. As shown

Broadly, clay minerals are structured of two principal units: tetrahedral (T) and octahedral (O) sheets [114, 115]. Each tetrahedron consists of a central cation (mostly Si4+) coordinated

corners (basal oxygens Ob) forming an infinite 2D hexagonal mesh (**Figure 12**). The fourth

three octahedral sites are occupied, leaving a vacant site and the generation of a dioctahedral or a gibbsite-like sheet. Clays can be classified into 1:1 and 2:1 types according to the layering

and/or OH−

or OH<sup>−</sup>

a trioctahedral or a brucite-like sheet is produced, if it is trivalent (Al3+

**Figure 11.** Schematic design and kaolin and kaolin compounds for the treatment of tumors [113].

 (apical oxygen Oa) remains unshared, lying perpendicular to the tetrahedral sheet, and is the main site of interaction with the octahedral sheet. Each octahedron consists of a metal

anions and linked to adjacent tetrahedra through three shared oxygens on the

anions. Adjacent octahedra are linked to each

),

179

), then two out of every

), forming an octahedral sheet. If Mn is divalent (Mg2+

Development of Clay Nanoparticles Toward Bio and Medical Applications

http://dx.doi.org/10.5772/intechopen.77341

in **Figure 11**, it is used for the treatment of tumors [113].

**2.13. An overview of clay chemistry**

) coordinated to six O2<sup>−</sup>

other by sharing edges (two O2<sup>−</sup>

to four O<sup>2</sup><sup>−</sup>

cation (*M<sup>n</sup>*<sup>+</sup>

O<sup>2</sup><sup>−</sup>

**Figure 9.** XRD patterns of MMT and 5-FU-MMT [106].

**Figure 10.** The schematics of donepezil interference in clay nanomaterials: (a) the dual-layer composition and (b) the single-layer composition [106].

## **2.12. 2D clay nanoparticles for drug delivery in cancer treatment**

Two-dimensional kaolinite clay nanoparticles are used in the drug delivery system. The increasing of spacing of the kaolinite nanoparticles from 0.72 to 4.16 nm is due to the interference of guest species with different chain lengths of organic materials that can increase the drug delivery efficiency and reduce the toxicity of doxorubicin (DOX). The kaolinite (Kaolin) and kaolin compounds show a high level of biocompatibility and low toxicity against pancreatic cancer cells, gastric cancer, prostate cancer, breast cancer, esophageal cancer, and thyroid cancer diagnosis. However, lung cancer and leukemia require structural harder compounds for drug delivery. DOX-Kaolin and its internal contents exhibit more drug release rates in acidic environment than in the neutral environment. The use of two-dimensional clay nanoparticles for a drug delivery system can pave the way for high-performance nanotherapies with superior antitumor efficacy and significant reduction of side effects. As shown in **Figure 11**, it is used for the treatment of tumors [113].
