Trypsin-loaded mesoporous silica as a sensing material for amplified detection of ATP4 − ions

Abstract

In this study, we describe a new method for the detection of an analyte with amplification using enzyme-loaded, polyaminated mesoporous silica. Enzymes with different molecular sizes (trypsin, alkaline phosphatase and glucose oxidase) were tested for loading in the pores of the mesoporous materials. Among the enzymes examined, only trypsin was loaded in the pores (diameter 2.8–5 nm) of the mesoporous silica. The enzymatic activity of trypsin loaded in the pores (2.8 nm) of polyaminated MCM-41(C14) was controlled by an analyte (ATP4 − ) that binds to the polyamine sites. The formation of p-nitroaniline from a substrate, N-α-benzoyl-DL-arginine-4-nitroanilide hydrochloride, in the presence of loaded trypsin was decreased by ATP4 − in the concentration range from 1.0 to 50 μM in a 2-[4-(2-hydroxyethyl)-1-piperazyl] ethanesulphonic acid buffer solution (pH 7.4). The response was selective to ATP4 − over ADP3 − , GMP2 − and phosphate. The potential use of trypsin-loaded mesoporous silica for the design of a sensing system with amplification ability is discussed in terms of working principle, the effect of pore sizes, sensitivity, selectivity and a signal transduction factor.