**10. Conclusion**

*Materials at the Nanoscale*

product delivery [48].

the cluster [81].

interactions with the living cells. Therefore, this situation requires many in- depth studies about the interaction nature between ND particles and the living cells. For example, some types of ND have a strong tendency to aggregate in specific medium which hindering and limiting their applications [48]. In fact, this aggregation tendency is related upon some synthesis techniques leads to produce ND particles with high dangling bonds on their surface such as detonation technique [48]. Hence the free electrons of the surfaces tend to form many functional groups and then these functional groups tend to form covalent bonds with the primary particle forming core- aggregates [48]. On the other side, the existing of sp2C around ND

Several methodologies have been carried for disintegration process, the most attractive one is the beads assisted sonication method which involving the double actions of shear force (induced by using zirconia beads) and cavitation effect (induced by ultrasound waves). The results shows colloid stability for one year after sonication for one hour [80]. While surface functionalization process has been recommended as an active way to reduce the aggregation size of ND. In fact there are several surface functionalization techniques, one of them involving generating specific surface radicals which then will act as a substrate used for synthesis of ND

From a biocompatibility point of view, several studies have been demonstrated

that ND toxicity can be varied and it is affected by surface chemistry of ND, cell- line type and the composition of treatment medium. In this field, the mitochondrial activity and the inflammatory activity of the cell have been used as toxicity indicator. So depending on these keys and the results of many clinical experiments, it was found that there is no manifestation of toxicity with ND dose (100 μg/ml concentration) after 24 hour of incubation period [81]. In addition, ND with high loading capacity, payload with high concentrations is allowed via using less delivery agents in association with the ability of releasing the cargo from the carrier in controlled manner, these two important features of ND developing the bio- applications of them either for small molecules delivery or for bio- technology

In 2007, the suitability of ND particles as a delivery agent of doxorubicin hydrochloride (DOX) was studied by H. Huang et al. [81]. The study was based on the rationale that the surface carboxylic and hydroxylic groups of ND can interacts with the amine groups of DOX via ionic- forces when dispersing them in aqueous medium. The surface loading of DOX on ND particles was increased from 0.5 to 10 wt% via addition of 1% solution of sodium chloride to their aqueous dispersion, and the removal of salt favored the release of DOX. ND particles loaded with DOX were recommended to assemble in the form of loose- clusters, such that a certain amount of DOX adsorbed on the ND particle's surface resides within the cavity of

This methodology of drug- entrapment in loose aggregates of ND particles could provide a feature by minimizing the systemic adverse effects of the naked- DOX. Thus, ND-based delivery systems could overcome the problem to the use of high concentrations of chemotherapeutic drugs in cancer treatments. In addition, the lower levels of cytotoxicity of the ND-DOX composites in mouse macrophages and human colorectal cancer cells compared with bare DOX in a 48-hour period could be beneficial in sustained drug release [81]. The potential of using ND particles as a targeted protein-delivery- vehicle was investigated in a pH-dependent system. By means of the physical- adsorption, ND particles achieved a considerable high surface loadings of bovine insulin about80% in pH-neutral water with a weight ratio of 1:4 of insulin:ND. Also, the aggregation properties of the insulin improved after interacting with ND particles. This propose that ND particles have the ability to

leads to bond these particles together into core aggregate [48].

with carboxylic acid and dicarboxylic acid functionalization [48].

**102**

In summary, fullerene and nanodiamonds have been studied for drug delivery applications. Fullerenes and nanodiamonds are attractive allotropes in the carbon nanomaterials family. They can be synthesized with attractive properties in higher purity, higher surface homogeneity, and different surface functionalization and in controlled sizes that make them essential in nanomedicine fields. Utilization of fullerenes and nanodiamonds in drug delivery systems show higher advantages with enhanced targeted delivery and controlled drug release ability than other traditional strategies. But on the other side, further in-depth research about toxicity concerns are necessary in order to achieve the full advantages of utilization these nanomaterials in human body.

## **Author details**

Basma H. Al-Tamimi\* and Saad B.H. Farid Department of Materials Engineering, University of Technology, Baghdad, Iraq

\*Address all correspondence to: 130074@uotechnology.edu.iq

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