Grafting of biotin on top of a polycrystalline boron-doped diamond layer was achieved by surface oxidation followed by an esterification reaction and revealed by fluorescently labelled streptavidin.

Base excision repair (BER) is the major mechanism for the correction of damaged nucleobases resulting from the alkylation and oxidation of DNA. The first step in the BER pathway consists of excision of the abnormal base by several specific DNA N-glycosylases. A decrease in BER activity was found to be related to an increased risk of carcinogenesis and aging. To investigate BER activities we set up a new device for DNA repair analysis based on surface plasmon resonance imaging (SPRi). Oligonucleotides bearing an abnormal nucleoside, namely 8-oxo-7,8-dihydro-2′-deoxyguanosine and (5′S)-5′,8-cyclopurine-2′-deoxynucleoside, were grafted by a pyrrole electro-copolymerization process on a glass prism coated with a gold layer. The latter label-free DNA sensor chip permits the detection ofN-glycosylase/AP-lyase activity as well as the binding of repair proteins to DNA damage without cleavage activity. Thus, the Fapy DNA N-glycosylase (Fpg) protein is shown as expected to bind and then cleave its natural substrate, namely 8-oxo-7,8-dihydro-guanine, together with the resulting abasic site. Using the current SPR imaging-based DNA array we observed an original binding activity of Fpg towards the (5′S)-5′,8-cyclodAdenosine residue. These results altogether show that SPR imaging may be used to simultaneously and specifically detect recognition and excision of several damaged DNA nucleobases, and constitutes an interesting technique to screen inhibitors of DNA repair proteins.

Headspace analysis of highly humid samples remains a challenge for artificial olfaction. Based on surface plasmon resonance imaging and bio-based sensors, the NeOse Pro olfactive analyzer yields multivariate data and enhances the statistical discrimination capacity of odor patterns. However, the presence of a high background signal, such as water vapor from aqueous samples, may deteriorate its discriminant ability. Recently, miniaturized pre-concentrators packed with hydrophobic adsorbent have been developed to improve the detection limit of gas analysis methods and to enhance their selectivity by reducing the water’s background signal. This work presents, for the first time, the coupling of a miniaturized silicon micro pre-concentration unit (µPC) to a bio-based opto-electronic nose (NeOse Pro). The results showed that the coupling of a silicon µPC with the NeOse Pro led to an improvement in the detection limit of n-nonane by at least a factor of 125. Additionally, principal component analysis (PCA) of eight different flavored waters showed an enhanced discrimination ability of the coupled set-up in highly humid conditions.