Recognition of Rhodobacter sphaeroides by microcontact-imprinted poly(ethylene-co-vinyl alcohol).

The immobilization of cells or microorganisms is important for bioseparations, in bioreactors producing cellular metabolites, and as receptors for biosensing. Cell-imprinted polymers (CIPs) have been shown to have cavities with complementary shapes and also high affinities for the template cells or microorganisms. However, the effects of binding to CIPs on gene expression are only beginning to be studied. In this work, the purple bacteria Rhodobacter sphaeroides was employed as a model for the imprinting of microorganisms. R. sphaeroides was first adsorbed on a glass slide as the stamp and then microcontact-imprinted onto poly(ethylene-co-vinyl alcohol), EVAL. The surfaces of the R. sphaeroides-imprinted (RsIPs) and non-imprinted (NIPs) EVAL thin films were examined by Raman spectrometry and scanning electron microscopy. The expression of the nitrogenase (nitrogen fixation, nifH) gene of R. sphaeroides adsorbed on both the RsIPs and NIPs EVAL thin films was also measured by the quantitative reverse transcription polymerase chain reaction (qRT-PCR); cells grown on imprinted polymer showed dramatic differences in gene expression compared to controls.