Electrospun polyethersolfone nanofibrous membrane as novel platform for protein immobilization in microfluidic systems.

In the present study, the feasibility of electrospun polyethersolfone (PES) nanofibrous membrane as the solid substrate for microfluidic based immunoassays to enhance the density of immobilized antibody on the surface of membrane was assessed. Conversely, the efficacy of antibody immobilization was compared by two different strategies as 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-Hydroxysuccinimide (NHS) coupling chemistry and hydrophobic interaction. Compared to conventional immunoassays carried out in plates or gels, microfluidic based immunoassays grant a lot of advantages such as a consumption of little samples and reagents, shorter analysis time, and higher efficiency. Therefore, microfluidic immunoassays can be efficiently used as a point-of-care device in medical diagnosis. Surprisingly, we found the increase of specific surface areas of the microfluidic channels improve density of immobilized proteins and leads to higher signal strength. Anti-staphylococcus enterotoxin B (anti-SEB) was used as an analyte model to demonstrate the utility of our proposed platform. Fluorescent microscopy, Fourier transform infrared spectroscopic (FTIR), gas adsorption, contact angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Uv-Vis spectrophotometer and atomic force microscopy (AFM) techniques were used to assess the efficacy of antibody immobilization on the surface. To understand dominant mechanism of protein immobilization, zeta potential measurement was also carried out and it was found electrostatic attraction play significant role in antibody immobilization running into micro- channels containing through EDC/NHS. Moreover, incorporation of nanofibrous membrane causes significant improvement in the signal detection of microfluidic based immunoassay.