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

Abstract

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. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1108-1120, 2018.

Different types of electrospun nanofibers and their effect on microfluidic‐based immunoassay

“…In this mechanism, EDC/NHS adsorbed on the different substrate through different physical bonding, namely, hydrogen bonding, electrostatic attraction, hydrophobic interactions, and pi‐pi attraction. After EDC/NHS adsorption on the surface, protein molecule could be immobilized covalently through functional group of EDC/NHS or electrostatically …”

“…After EDC/NHS adsorption on the surface, protein molecule could be immobilized covalently through functional group of EDC/NHS or electrostatically. 37 In order to support our hypothecation, we also examined the influence polymer type on the performance of immunoassay for the detection of SEB. For this purpose, in addition to PES, three other types of polymers, which contained functional groups of carboxyl and hydroxyl in their structure, namely, PLLA, PLGA, and PCL, were also chosen for immunoassay performance.…”

“…In this regard, several protein immobilization strategies have been developed to improve the sensitivity of designed immunoassays including covalent and affinity immobilization. In the previous studies, we have demonstrated the feasibility of using electrospun polyethersolfone (PES) e.NFM as the solid substrate for microfluidic‐based immunoassays in order to enhance the density of immobilized antibody on the surface of membrane by two different strategies of 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC)/ N ‐hydroxysuccinimide (NHS) coupling chemistry and hydrophobic interaction. Results showed that simultaneous use of e.NFM and EDC/NHS provides synergic effect on protein immobilization onto the microchannels.…”

Different PES nanofibrous membrane parameters effect on the efficacy of immunoassay performance

“…As all we know, the most important type of recognition elements is antibodies, and for this purpose, we chose antibody to immobilize on the e.NFM through two different approaches of simple physical adsorption and the more complex one, namely, covalent immobilization through EDC/NHS‐coupling chemistry to compare efficacy. It is well known that coupling with EDC/NHS mainly occurred by the condensation reaction of an amino group from one element with the carboxyl group of a second element …”

Electrospinning and microfluidics

“…In alternative, non-water-soluble electrospun nanofibers have been variously functionalized and used as a substrate for microfluidic HIV immunoassays [78], Escherichia coli detection [88], and on-chip sample concentrators [87]. To this aim, standard immobilization procedures have been purposely modified to functionalize nanofiber mats after being bonded into microfluidic channels [88,91]. In these applications, the non-water-soluble nanofibers could withstand the fluid flow within the channels, dramatically increasing the functional surface area available within the devices.…”