Simple model for hydrolytic degradation of poly(lactic acid)/poly(ethylene oxide)/carbon nanotubes nanobiosensor in neutral phosphate-buffered saline solution

In this study, the hydrolytic degradation of poly(lactic acid) (PLA)/poly(ethylene oxide) (PEO) blend and PLA/PEO/carbon nanotubes (CNTs) nanobiosensors in neutral phosphate-buffered saline (PBS) solution was investigated by experimental and theoretical approaches. A simple model was developed to estimate the degradation fraction by applying the average degradation rate (K) and time exponent. The predictions of the developed model were compared to the experimental results. Moreover, CNT concentration, CNT size, sample thickness, diffusion coefficient, and concentration of the PEO phase influenced the K value. The impacts of the parameters on the degradation rate were studied to confirm the developed equation. All samples were rapidly degraded during the first week, while the degradation slowly progressed in the following weeks. The experimental and theoretical results demonstrate that CNTs quicken the degradation of samples. The degradation fraction of a nanobiosensor depends directly on the values of K and the time exponent. Furthermore, a high concentration of PEO, small thickness of the sample, high concentration of thin CNTs, and high diffusion coefficient desirably improve the degradation rate.