A device comprising a modified porous membrane is provided. The modified porous membrane comprises a polymer coating grafted to a porous membrane. The device is used for analyte detection from a biological sample using an immunoassay. The device comprises a sample application zone at one end of the device for applying a biological sample comprising a target analyte; and a detection zone present at another end of the device, downstream of the sample application zone for detecting the target analyte, wherein the detection zone comprises one or more first biomolecules immobilized on a modified porous membrane having a structure of Formula (I).