In order to improve the steric hindrances and less ordered structures in the long-chain SAMs, the SAM of 4,4-Dithiodibutyric acid (4,4- DTBA) was investigated to be a thin monolayer for the protein chip. This work presents the feasibility study of 4,4- DTBA as a monolayer of the protein chip based on gold surface. Characterizations of surface topography using atomic force microscopy (AFM), contact angle and fluorescence using protein A-FITC were performed to investigate the binding efficiency for the SAMs of 4,4- DTBA and 11- mercaptoundecanoic acid (11- MUA). The results show that the binding efficiency of 4,4- DTBA is higher than that of 11- MUA. The SAM of 4,4-DTBA can be used as a monolayer for the protein chip and may have a comparable binding efficiency.