Abstract:
Controlled release delivery systems improve treatment efficacy by delivering drugs in a controlled manner to maintain concentrations at therapeutic levels. Polypyrrole (PPy), an intrinsically conducting polymer (ICP), is one of the most studied ICPs largely due to its high stability, ease of preparation and biocompatibility. Triggered drug delivery from PPy takes advantages of changes in permeability to ions and volume which are dependent on redox state. A PPy drug delivery system, prepared from a poly (methyl methacrylate) (PMMA) template, has been developed to provide control release of excitatory neurotransmitter L-glutamic acid. L-glutamic acid was loaded into porous PPy structures and the influence of electrical stimulation on release was investigated. A validated high performance liquid chromatography (HPLC) method using an autosampler to carry out derivatization was developed to quantify L-glutamic acid. PPy scaffolds were fabricated in a square stainless steel wells to minimize unstimulated drug release. Drug loading protocol to enhance loading levels, and the influence of different dopants on drug release were investigated. Scanning electron microscopy (SEM) was used to study the morphology of the porous PPy structures. Cyclic voltammograms demonstrated the porous PPy was a conductive material with repeatable oxidation and reduction processes evident. Fourier transform infrared (FTIR) peaks showed the presence of anionic dopants dodecyl benzene sulfonate (DBS) and p-toluene (pTS) within the polymer. The porous PPy structures were capable of controlling the release of Lglutamic acid out of the structure, despite no clear effect of electrical stimulation. In this research, a validated HPLC method was developed for the quantification of Lglutamic acid. Porous PPy structures were successfully fabricated and loaded with higher levels of bioactive than previously reported. These structures could in the future be used to deliver bioactive molecules in a triggered fashion.