**Author details**

Oral administration of γCDs has insignificant irritation followed by rapid and complete degradation to glucose by intestinal enzymes. They are therefore deemed the least toxic [12, 128]. α and βCDs are also known for their renal toxicity [127]. βCD is not used in parenteral formulations and the use of αCD is seriously limited due to toxicological consideration [123]. Parent CDs (α and β) and lipophilic CD derivatives such as m-βCD are also not suitable for parenteral formulation due to their rapid absorption by the gastrointestinal track; however, they are suit-

The newly discovered CD derivatives with better safety profiles have sparked a renewed interest in the use of CDs, especially for those that will find way into human and animal bodies. For example, HP-βCDs and sulfobutylether-βCDs are used in parental formulations in very high concentrations [123, 129]. The concentration, type of administration and time of exposure play a critical role in determining the level of toxicity and safety of CDs and their derivatives. It is therefore generally thought that CDs and their derivatives can be safely used in membrane technology and other applications without toxicological problems in case they leach out and be ingested by humans or

animals, especially in areas such as wound dressing, water treatment and air purification.

One of the major challenges in the production of CD nanofibers is the inability to electrospin CDs directly, i.e., without the need to blend them with other copolymers or modifying their structure. The poor solubility of CDs in water and organic solvents makes it impossible to electrospin CDs directly. Hence, the most feasible way is to blend the CDs with other flexible polymers. Indeed, many studies have reported the fabrication of CD-based nanofibers using copolymers. In membrane technology, the main challenge is their high water solubility, which results in the loss of structure and functionality of membranes once the CDs are dis-

The application of these materials varies significantly. Workers are currently exploring the commercial viability of CD-based fibers especially in areas of water treatment. Their use in various applications is possible due to their ability to form inclusion complexes with various compounds. The chemistry responsible for this complexation is now well understood. The performance of CD-based materials can thus be ascertained or monitored using simple phase-solubility diagram. Further, the high surface area-to-volume ratio of nanofibers and modification possibilities of CD molecules have motivated the use of CD nanofibers in areas such as tissue engineering and water treatment. The nanofiber morphology is preferred over other morphologies of the CD polymers, which tend to possess lower surface areas. The electrospinning technique can now produce large quantities of nanofiber membranes and makes it viable to use the materi-

In general, CDs are less toxic and environment-friendly materials due to their biodegradable nature. CDs and their derivatives have unique properties such as high porosities,

als in large-scale quantities. However, the cost is yet to be ascertained.

able for oral formulations [123, 127].

158 Cyclodextrin - A Versatile Ingredient

**8. Challenges and perspectives**

solved and washed away.

**9. Conclusion**

Mandla B. Chabalala<sup>1</sup> , Bonisiwe C. Seshabela<sup>1</sup> , Stijn W.H. Van Hulle<sup>2</sup> , Bhekie B. Mamba<sup>1</sup> , Sabelo D. Mhlanga<sup>1</sup> and Edward N. Nxumalo<sup>1</sup> \*

\*Address all correspondence to: nxumaen@unisa.ac.za

1 Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering and Technology, University of South Africa, Johannesburg, South Africa

2 Department of Green Chemistry and Technology, Ghent University Campus Kortrijk, Belgium
