Interface potential sensing from adsorption of human serum albumin (HSA) on carbon nanotube (CNT) monitored by zero current potentiometry for HSA determination

• The interface potential from the adsorption of human serum albumin (HSA) on multiwall carbon nanotube (MWNT) at the MWNT/solution interface was extracted as sensing parameter for the first time.
• The zero current potential (the interface potential) was mentioned with zero current potentiometry.
• The fundamental relationship between the zero current potential (the interface potential) and the HSA concentration was established.
• For the determination of HSA, the zero current potential is proportional to the HSA concentration with the high slope.

In this work, the adsorption of human serum albumin (HSA) on the bare multiwall carbon nanotube (MWNT) was investigated by a new electrochemical method, termed as zero current potentiometry. For this, a MWNT strip was prepared by directly adhering MWNTs on the transparent adhesive tape surface. Moreover, when HSA adsorbed onto MWNT at the MWNT/solution interface, an interface potential Ψ yielded. The interface potential Ψ as the zero current potential Ezcp simply related to it was monitored by zero current potentiometry. The relationship between the zero current potential Ezcp, the HSA concentration and others was established in simple stoichiometric relation. Based on this, both the adsorption of HSA on MWNT and the HSA determination can be studied. For the HSA determination, the theoretic conclusion consisted with experimental results. The zero current potential Ezcp was proportional to the HSA concentration in the range of 2.8×10−8–3.4×10−7 M with the limit of detection 2×10−8 M. The linear regression equation was Ezcp/V (vs, SCE)=(0.159±0.01)+(0.358±0.02)×106CHSA (µM). This determination was fast, high sensitive and good selective