Drug-loaded polymer nanofibers

Figure 7.1 Illustration of the three morphological models of drug-loaded polymer nanofibers.

K. Saha, B.S. Butola, M. Joshi, Drug-loaded polyurethane/clay nanocomposite nanofibers for topical drug-delivery application, J. Appl. Polym. Sci. 131 (2014). 

The kinetics of release of the drug is controlled by the semicrystaUine nature of the polymer as well as by the morphology of the polymer/drug composite. Three basic morphological models for dmg-loaded polymers (or polymer particles), first proposed by Kissel et al. (1993) apply to drug-loaded nanofibers as well (Verreck et al. 2003a) ... 

Another detailed and recent description of the diffusion processes for molecules released from polymer nanofibers is based on the desorption-limited theory of admixture release.In this case, the release is mainly driven by desorption, or dissolution, from nanopores on the surface of the polymer nanostructures. To describe this mechanism, one firstly defines a so-called nanoporosity factor, Np, as the ratio of the initial amount of drug admixture on the nanofiber surface, nisur/O), and the total initial amount of drug loaded in the nanofibers, mp(0) [i.e. the drug molecules on the surface plus those in the... 

At present a few studies of nanofibers and nanombes are focused on CNS drug delivery. One study evaluated electrospun nanofibers of a degradable polymer, PLGA, loaded with antiinflammatory agent, dexamethasone, for neural prosthetic applications (Abidian and Martin, 2005). A conducting polymer, poly(3,4-ethylenedioxythiophene), was deposited to the nano-fiber surface and the coated nanofibers were then mounted on the microfabricated neural microelectrodes, which were implanted into brain. The drug was released by electrical stimulation that induced a local dilation of the coat and increased permeability. 

Fig. 1 Nanofiber modification strategies. In step 1, many polymer and solution properties will affect the size, stability, and reactivity of nanofihers in the final mat, including multipolymer blending strategies, incorporation of soluble factors/drugs/spheres, and/or loading concentrations. In step 2, during spinning, the ambient conditions and voltage applied must be tailored for each polymer source and can be dictated by the nature of the collector or the number of jets employed simultaneously. In step 5, the as-spun mat can be modified by various crosslinking techniques to stabilize the polymers or, in the case of soluble or carrier polymers, these can be leached out by subsequent liquid washes...

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