**7. Toxicology and safety of CDs and their derivatives**

Even though CDs have several advantages for applications in areas such as water treatment, tissue engineering and drug delivery, their toxicity, biological fates and safety issues need to be evaluated since they eventually find their way into animal and human bodies. The three most common natural CDs and their hydrophilic derivatives are known to only permeate lipophilic biological membranes, which include the gastrointestinal mucosa, skin and cornea of the eye with certain difficulty. CDs have been reported to be nontoxic to a certain level due to low absorption from the gastrointestinal track [12, 123, 124]. αCDs were found to bind with some lipids resulting in eye irritation in rats when they were orally administered, whereby 60% of the dose was excreted as CO<sup>2</sup> , 26–33% as metabolite incorporation and 7–14% as metabolites in urine and feces [12, 125]. Oral administration in rats showed that βCDs have less irritation compared to αCDs; however, small amounts were absorbed in the upper intestinal track [12, 126]. Even though they are nontoxic when administered orally, βCDs cannot be administered parenterally due to their low solubility in aqueous solutions and their nephrotoxicity [127]. 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 suitable for oral formulations [123, 127].

small diameters and high surface area-to-volume ratio rendering them practically usable in a wide range of applications including water treatment. Indeed, electrospinning these glycosidic sugars into nanofibrous mats improves their surface area-to-volume ratio further and enhances their adsorption and inclusion complexing properties. Undesirable species of specific sizes can be encapsulated *via* inclusion complexation and filtered by CD-based nanofibers and membranes. Electrospun CD nanofiber mats and membranes find further applications in various areas such as drug delivery, filtration, catalysis, water treatment, reinforcement, electronics, pharmaceuticals and optical devices. Considering that they are natural, nontoxic, cost-effective and readily available, their properties can be explored for further applications. Scaling-up and subsequent commercialization of these superior nanofibers and

Cyclodextrin-Based Nanofibers and Membranes: Fabrication, Properties and Applications

http://dx.doi.org/10.5772/intechopen.74737

159

We gratefully acknowledge the University of South Africa (UNISA) and Ghent University.

\*

1 Nanotechnology and Water Sustainability Research Unit, College of Science, Engineering

[1] Petrovic M. Fate and distribution of pharmaceuticals in wastewater and sewage sludge of the conventional activated sludge (CAS) and advanced membrane bioreactor (MBR)

[2] Kasprzyk-hordern B, Dinsdale RM, Guwy AJ. The removal of pharmaceuticals, personal care products, endocrine disruptors and illicit drugs during wastewater treatment and

[4] Gopal R, Kaur S, Ma Z, Chan C, Ramakrishna S, Matsuura T. Electrospun nanofibrous

filtration membrane. Journal of Membrane Science. 2006;**281**(1-2):581-586

its impact on the quality of receiving waters. Water Research. 2009;**43**(2):363-380 [3] Lin S, Juang R. Adsorption of phenol and its derivatives from water using synthetic resins and low-cost natural adsorbents: A review. Journal of Environmental Management.

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

, Stijn W.H. Van Hulle<sup>2</sup>

, Bhekie B. Mamba<sup>1</sup>

,

membranes can be explored once their cost has been determined.

, Bonisiwe C. Seshabela<sup>1</sup>

and Edward N. Nxumalo<sup>1</sup>

and Technology, University of South Africa, Johannesburg, South Africa

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

treatment. Water Research. 2009;**43**(3):831-841

**Acknowledgements**

**Author details**

Mandla B. Chabalala<sup>1</sup>

Sabelo D. Mhlanga<sup>1</sup>

Belgium

**References**

2009;**90**(3):1336-1349

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.
