Long-range surface plasmon resonance immunosensor based on water-stable electrospun poly(acrylic acid) fibers

Water-stable poly(acrylic acid) (PAA) fibers were fabricated on flat gold thin films via an electrospinning technique. The obtained fibers were then used to construct long-range surface plasmon resonance (LR-SPR) biosensors. Because LR-SPR spectroscopy has a greater evanescent field intensity and penetration depth than conventional surface plasmon resonance (SPR) spectroscopy, the increased surface area of the PAA fibers within the surface plasmon evanescent field was efficiently utilized for biosensor applications. The water-stable electrospun PAA fibers were obtained by adding β-cyclodextrin as a crosslinker, followed by thermal treatment at 150 °C for 40 min. In addition, the layer-by-layer deposition of poly(diallyldimethylammonium chloride) and PAA ultrathin films on the electrospun PAA fibers functionalized their surfaces and further increased their water-stability by increasing the number of active carboxylic acid groups. Fiber surfaces were then successfully activated for the construction of immunosensors for the detection of human immunoglobulin G. Therefore, the present study demonstrates the potential of electrospun fibers for LR-SPR biosensor applications.