This invention discloses using SPR technology to simultaneously and qualitatively detect the presence of infectious agent related antibodies and/or antigens in a serum sample, which can be used to screen for infectious agents in blood. It also discloses an efficient formula to make a mixed SAM that can greatly enhance the immobilization ability of the metal surface in SPR based techniques, which is good for the immobilization of relevant antigens and antibodies used for the screening of infectious agents in blood.