PMC:4996384 / 1144-4777 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/4996384","sourcedb":"PMC","sourceid":"4996384","source_url":"https://www.ncbi.nlm.nih.gov/pmc/4996384","text":"1. Introduction\nSmall molecules detection is of paramount importance in many areas ranging from pharmacology to environmental diagnostic [1,2,3]. The main difficulty in such diagnostic relates to the small size and low concentrations of the encountered targets [4]. Direct detection is generally impossible as the effect of the binding of the targets to the probes is usually close to noise signal. Indirect strategies are to be found in order to detect and quantify small molecules. The folding of the probes upon binding of the target is one common strategy. To this end, aptamers, short oligonucleotides selected specifically with high affinity towards a predefined target, present such behavior [5,6]. The sensitivity and selectivity of the aptamer towards the target is principally due to a particular three-dimensional folding (hairpins, three‑way junctions or G-quadruplex for example) enabling the target binding [7,8]. In fact, their three dimensional structure is necessary for and may be induced by the binding of the target. Whereas their folding upon binding of the target is relevant for proteins like thrombin, for small molecules, the aptamer is generally pre-folded before the target binds [9]. However, in recent years, a limited class of aptamers have been shown to keep most of their affinity despite the splitting of the sequence in two parts [10,11,12,13,14,15]. This is particularly the case of the adenosine aptamer whose hairpin sequence may be cut in the loop as this region is not directly involved in the adenosine binding [16,17]. Due to the two strands binding the targets, sandwich assays are possible, thus leading to the indirect detection of the targets. Solution phase detection using split-aptamers for the detection of adenosine gave detection limit of few micromolars.\nIn this study, we would like to extend this approach to a microarray format with Surface Plasmon Resonance imaging (SPRi) detection although SPRi has been known so far to be limited in term of resolution for the direct detection of small molecules (Molecular weight below 1 kDa) [18,19,20]. While good performances have been obtained for the detection of proteins [18,21,22], indirect strategies or improved sensibility should be considered for small molecules [23]. As an example, it can be done by taking benefit of using gold nanostructures for the sensitive detection of targets by plasmonic effects like SERS [24,25,26]. To this end, introducing gold nanoparticles in the detection process is a common strategy used to amplify SPRi signal due to their dual effect on plasmon (the standard mass effect and a coupling of the localized surface plasmon of the particles with the SPRi signal) [27]. However, this strategy requires a sandwich assay where two probes are respectively grafted on the biosensor surface and on the nanoparticles [28]. Split-aptamers are thus ideal probe candidates. In this paper, we combine both strategies: SPRi amplification signal thanks to gold nanoparticles along with sequence engineering of split-aptamer for sandwich assay format of detection. We developed dedicated functionalization chemistries of both gold surfaces, the SPRi prisms and the nanoparticles, in order to limit the non-specific adsorption. We analyzed the limit of detection for two particular adenosine split‑aptamer sequences. Three orders of magnitude difference in the LODs were observed depending on the existence or not of reference signal in absence of adenosine. For the split-aptamer sequence presenting a signal OFF- signal ON behavior, state-of-the-art performances have been obtained with a LOD as low as 50 nM.","divisions":[{"label":"Title","span":{"begin":0,"end":15}}],"tracks":[{"project":"2_test","denotations":[{"id":"27600212-16968051-69481612","span":{"begin":138,"end":139},"obj":"16968051"},{"id":"27600212-15649055-69481613","span":{"begin":140,"end":141},"obj":"15649055"},{"id":"27600212-16878905-69481614","span":{"begin":142,"end":143},"obj":"16878905"},{"id":"27600212-24817356-69481615","span":{"begin":262,"end":263},"obj":"24817356"},{"id":"27600212-1697402-69481616","span":{"begin":700,"end":701},"obj":"1697402"},{"id":"27600212-2200121-69481617","span":{"begin":702,"end":703},"obj":"2200121"},{"id":"27600212-9383468-69481618","span":{"begin":922,"end":923},"obj":"9383468"},{"id":"27600212-9368648-69481619","span":{"begin":924,"end":925},"obj":"9368648"},{"id":"27600212-23150810-69481620","span":{"begin":1208,"end":1209},"obj":"23150810"},{"id":"27600212-16131053-69481621","span":{"begin":1365,"end":1367},"obj":"16131053"},{"id":"27600212-19309141-69481622","span":{"begin":1368,"end":1370},"obj":"19309141"},{"id":"27600212-22715870-69481623","span":{"begin":1371,"end":1373},"obj":"22715870"},{"id":"27600212-21761903-69481624","span":{"begin":1374,"end":1376},"obj":"21761903"},{"id":"27600212-18651718-69481625","span":{"begin":1377,"end":1379},"obj":"18651718"},{"id":"27600212-24033257-69481626","span":{"begin":1380,"end":1382},"obj":"24033257"},{"id":"27600212-19562201-69481627","span":{"begin":1555,"end":1557},"obj":"19562201"},{"id":"27600212-17263339-69481628","span":{"begin":2087,"end":2089},"obj":"17263339"},{"id":"27600212-19770865-69481629","span":{"begin":2093,"end":2095},"obj":"19770865"},{"id":"27600212-17263339-69481630","span":{"begin":2172,"end":2174},"obj":"17263339"},{"id":"27600212-22863116-69481631","span":{"begin":2175,"end":2177},"obj":"22863116"},{"id":"27600212-24069412-69481632","span":{"begin":2178,"end":2180},"obj":"24069412"},{"id":"27600212-18229953-69481633","span":{"begin":2269,"end":2271},"obj":"18229953"},{"id":"27600212-10976070-69481634","span":{"begin":2422,"end":2424},"obj":"10976070"},{"id":"27600212-24549396-69481635","span":{"begin":2701,"end":2703},"obj":"24549396"},{"id":"27600212-17485203-69481636","span":{"begin":2848,"end":2850},"obj":"17485203"}],"attributes":[{"subj":"27600212-16968051-69481612","pred":"source","obj":"2_test"},{"subj":"27600212-15649055-69481613","pred":"source","obj":"2_test"},{"subj":"27600212-16878905-69481614","pred":"source","obj":"2_test"},{"subj":"27600212-24817356-69481615","pred":"source","obj":"2_test"},{"subj":"27600212-1697402-69481616","pred":"source","obj":"2_test"},{"subj":"27600212-2200121-69481617","pred":"source","obj":"2_test"},{"subj":"27600212-9383468-69481618","pred":"source","obj":"2_test"},{"subj":"27600212-9368648-69481619","pred":"source","obj":"2_test"},{"subj":"27600212-23150810-69481620","pred":"source","obj":"2_test"},{"subj":"27600212-16131053-69481621","pred":"source","obj":"2_test"},{"subj":"27600212-19309141-69481622","pred":"source","obj":"2_test"},{"subj":"27600212-22715870-69481623","pred":"source","obj":"2_test"},{"subj":"27600212-21761903-69481624","pred":"source","obj":"2_test"},{"subj":"27600212-18651718-69481625","pred":"source","obj":"2_test"},{"subj":"27600212-24033257-69481626","pred":"source","obj":"2_test"},{"subj":"27600212-19562201-69481627","pred":"source","obj":"2_test"},{"subj":"27600212-17263339-69481628","pred":"source","obj":"2_test"},{"subj":"27600212-19770865-69481629","pred":"source","obj":"2_test"},{"subj":"27600212-17263339-69481630","pred":"source","obj":"2_test"},{"subj":"27600212-22863116-69481631","pred":"source","obj":"2_test"},{"subj":"27600212-24069412-69481632","pred":"source","obj":"2_test"},{"subj":"27600212-18229953-69481633","pred":"source","obj":"2_test"},{"subj":"27600212-10976070-69481634","pred":"source","obj":"2_test"},{"subj":"27600212-24549396-69481635","pred":"source","obj":"2_test"},{"subj":"27600212-17485203-69481636","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"2_test","color":"#ec93d5","default":true}]}]}}