Electrospinning of cyclodextrins: hydroxypropyl-alpha-cyclodextrin nanofibers

This study summarizes the polymer-free electrospinning of nanofibers from hydroxypropyl-alpha-cyclodextrin (HP-α-CyD). The viscosity and conductivity of HP-α-CyD solutions were studied, and HP-α-CyD concentrations from 160% up to 240% (w/w) were examined in order to find the optimal conditions for the electrospinning of uniform and bead-free HP-α-CyD nanofibers. We further extend our study by considering some industrially relevant scenarios for the preparation of HP-α-CyD solutions for the electrospinning process. For instance, distilled water, tap water and salty water (i.e., 1% NaCl, w/w) were used for the preparation of HP-α-CyD solutions, which significantly change the solution conductivity, and its effect on the electrospinning of HP-α-CyD was examined. It was observed that the higher solution conductivity was the dominating factor for obtaining bead-free and thinner HP-α-CyD nanofibers from less concentrated HP-α-CyD solutions. Yet, electrospinning of HP-α-CyD from salty water having higher solution conductivity yielded less uniform HP-α-CyD nanofibrous web. Moreover, the HP-α-CyD solutions were stored for certain time period (1 h, 1 day, 2 days, 4 days and 8 days) prior to electrospinning in order to study effect of storage time of the HP-α-CyD solutions. There was no significant viscosity change for HP-α-CyD solutions over time (up to 8 days), and therefore, the electrospinning of HP-α-CyD solutions resulted similar fiber morphology regardless of storage period. In all cases, the electrospinning of HP-α-CyD nanofibers yielded self-standing nanofibrous webs in the form of flexible nonwoven structure.