Immunoassay on Free-Standing Electrospun Membranes

For the purpose of immunoassay, electrospun membranes can be thought as the threadlike self-assembling of nano/microbeads. Nonwoven membranes of electrospun poly(epsilon-caprolactone) (PCL) fibers display excellent tenacity, flexibility and suitable surface energy. These PCL membranes exhibit easy handling in air, fast spreading, and wetting in aqueous solution, and rapid adsorption of protein molecules by hydrophobic interaction. After a fold-and-press process, the membrane porosity was reduced from similar to 75 % to less than 10 %, whereas the thickness increased From 5.3 to 280 mu m. The resulting fluorescence signal from adsorbed protein increased > 120x. With anti-HSA and HSA-FITC as an immunoassay model, a linear detection range from 500 ng/mL down to 1 ng/mL is obtained, with a detection of limit (LOD) OF similar to 0.08 ng/mL. By comparison, conventional nitrocellulose and a 24.3 mu m PCL fiber electrospun membrane displayed a much higher LOD of similar to 100 ng/mL. Immunoassay on free-standing electrospun membrane successfully combines the low-cost and simplicity of conventional membrane immunoassay, with the fast reaction speed and high sensitivity characteristic of magnetic nano/microbeads bioassays.