Cyclodextrin Nanosponges in Drug Delivery and Nanotherapeutics

The drug delivery technology landscape has become highly competitive and rapidly evolving as more and more developments in delivery systems are being integrated to optimize the efficacy and cost effectiveness of therapy. Currently, extensive research in the field of nanotechnology and nanomedicines is ongoing with a major focus towards manipulating materials at nanoscale; which can subsequently lead to advancements in diagnosis, imaging as well as treatment of a broad spectrum of diseases. In wake of recent findings, cyclodextrin based nanosponges comprising of hyper-crosslinked cyclodextrin polymers, are trendsetting in modern times with nanostructured three-dimensional network. Nanosponges based systems can address the issues related to solubility, absorption, penetration, bioavailability, in vivo stability, and can achieve sustained and targeted delivery with maximum therapeutic efficacy for a number of pharmaceutical entities. Molecules having molar mass between 100 and 400 Da, and with less than five condensed rings can be easily entrapped into nanocavities. For synthesizing nanosponges, melt method, solvent method, quasi-emulsion solvent diffusion, ultrasound and microwave assisted method can be adopted. Nanosponges synthesized via microwave method exhibits narrow size distribution, and higher crystallinity and drug loading (~2 fold) than the counterparts synthesized via conventional methods. Among diverse types, carbamate nanosponges have notable ability of binding to the organic molecules with loading capacity of 20–40 mg per cm3, and ~84% of dissolved organic carbon can be taken away from waste water; hence mostly used for water purification. However, polarity and flexible dimensions are the distinct features of carbonate nanosponges, and via synthetic reaction under different conditions, carbonate nanosponges can be obtained in amorphous or semi-crystalline form. Ester nanosponges have ability to host apolar organic molecules together with the cations, owing to presence of free polar carboxylic group. Lately, stimuli-responsive, intelligent or smart polymeric nanosponges have also been proposed for controlled delivery of low molecular weight and macromolecular drugs. In all, cyclodextrin nanosponges based drug delivery systems have achieved two to tenfolds improved stability, four to 25-folds enhanced solubility and three to fivefolds increased drug targeting efficiency; when compared to direct injection. The extension of nanosponges based drug delivery systems is an exhilarating and demanding research pasture, predominantly to overcome problems allied to existing formulations and for the further progressions in the field of pharmaceutical sciences and technology. Herein, nanosponges has been extensively reviewed as novel nanocarrier and adjunct with an all-inclusive focus on the suitability, versatility and characteristics of cyclodextrin based nanosponges for the promising applications in the fields of drug delivery and nanotherapeutics. Additionally in this chapter, development of nanosponges with a major focus on cyclodextrin based nanosponges has been well covered, and special importance has been given on discussing the preparation methods, characterization techniques and prominent applications of these novel drug delivery carriers for therapeutic purposes.