PCL fibers

Release of tetracycUne hydrochloride from PCL fibers was evaluated as a means of controlled administration to periodontal pockets (69). Only small amounts of the drug were released rapidly in vitro or in vivo, and poly(ethylene-co-vinyl acetate) gave superior results. Because Fickian diffusion of an ionic hydrochloride salt in a UpophiUc polymer is unlikely, and because PCL and EVA have essentially identical Fickian permeabilities, we attribute this result to leaching of the charged salt by a mechanism similar to release of proteins from EVA (73). Poly-e-caprolactone pellets have been found unsuitable for the release of methylene blue, another ionic species (74,75). In this case, blending PCL with polyvinyl alcohol (75% hydrolyzed) increased the release rate. 

Starch/PCL fiber bonded microscaffolds with electrospun nanofibers... 

The electrospinning of poly(s-caprolactone) (PCL) solutions have been reported by Reneker et al. [74]. They varied the PCL solution concentrations between 14 and 18 wt%. The instability in the electrospinning of PCL results in the contact and merging of segments in different loops of the electrospinning jet to form garlandlike fibrous structures [74]. Yoshimoto et al. [75] have studied the potential of electrospun PCL fiber mats for use in bone tissue engineering. They found that the... 

Figure 1.10 Scanning electron micrographs of electrospun poly( -caprolactone] [PCL] fibers formed from solutions of varying PCL concentrations in methylene chloride and N,N-dimethylformamide [DMF] [50/50 w/w) solvent. (A) 20 wt% PCL, [B] 40 wt.% PCL, and [C] chart of PCL concentration [wt.%] and fiber diameter [as mean standard deviation). Reprinted from Ref. 38, 2013 by MDPI.

Scaffolds made with collagen/PCL blend were compared with PCL scaffolds with [160] their surface modified by plasma treatment (p-PCL). p-PCL scaffolds were greater substrates for Schwann cells. The cells expressed bipolar elongations, retaining their normal morphology on the p-PCL fibers. p-PCL is a cost-effective material compared to PCL/collagen scaffolds, especially for peripheral nerve regeneration... 

Systematic Development of Electrospun PLA/PCL Fiber Hybrid Mats Preparation, Material Characterization, and Application in Drug Delivery... 

Electrospinning was carried out using an 8 wt%/v PLA solution mixed with each of three PCL solutions, namely, 9wt%/v HMW PCL solution, 15wt%/v HMW PCL solution, and 15 wt%/v LMW PCL solution. PLA and PCL solutions were mixed at different blend ratios of 1/0, 3/1, 1/1, 1/3, and 0/1 with three solvents, consisting of a DCM /DMF mixture at a blend ratio of 3/1, a chloroform/methanol mixture at 2/1 and a chloroform/acetone mixture at 2/1, along with the calculated PLA/PCL fiber compositions. Table 8.2. The mixing process continued at room temperature in a benchtop orbital shaking incubator for about 3 h. 

Formulation number Polymer composition In solution (wt%/v) PLA/PCL blend ratio in solution (v/v) Cosolvent type and composition in solution (v/v) PLA/PCL fiber composition... 

I 8 Systematic Development ofBectrospun PLA/PCL Fiber Hybrid Mats... 

Figure 8.6 SEM micrographs of dectrospun PLA/15% LMW PCL fibers with different blend ratios (a) 1/0, (b) 3/1, and (c) 1/1, using chloroform/methanol and (d) 1/0, (e) 3/1, and (f) 1/1, using chloroform/acetone [60]. The scale bars in SEM micrographs represent 10 pm.

The other point worth noting is that drug release occurred initially from the amorphous regions [75], in good accordance with Table 8.3 in which PLA/9% HMW PCL fiber mats show lower degree of crystallinity than PLA/15% HMW PCL counterparts. Such low crystallinity level can facilitate the improvement of fiber degradability and further influence the long-term TCH release. 

Haroosh, H.J., Chaudhary, D., and Dong, Y. (2012) Electrospun PLA/PCL fibers with tubular nanoclay morphological and structural analysis. J. Appl. Polym. Sci., 124, 3930-3939. 

Haroosh H.J., Chaudhary D., and Dong Y. (2011) Effect of solution parameters on electrospun PLA/PCL fibers. Proceedings of CHEMECA 2011 Conference, Sydney, Austraha, September 18-21, 2011. 

Figure 5. Contact angles as a function of average fiber diameter for PPFEMA coated electrospun PCL fiber mats. (Reproduced with permission from [31]. Copyright American Chemical Society, 2005.)...

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