Ordered supramolecular nanstructures of rod–coil molecular isomers were created by tuning the sequence of rod segments and altering the type of coil chain in bulk and in aqueous solution.

Abstract:The use of low-dimensional inorganic or organic nanomaterials has advantages for DNA and protein recognition due to their sensitivity, accuracy, and physical size matching. In this research, poly(3-methylthiophene) (P3MT) nanowires (NWs) are electrochemically prepared with dopant followed by functionalization with probe DNA (pDNA) sequence through electrostatic interaction. Various lengths of pDNA sequences (10-, 20-and 30-mer) are conjugated to the P3MT NWs respectively followed with hybridization with their complementary target DNA (tDNA) sequences. The nanoscale photoluminescence (PL) properties of the P3MT NWs are studied throughout the whole process at solid state. In addition, the correlation between the PL enhancement and the double helix DNA with various lengths is demonstrated.

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A highly sensitive flow injection analysis (FIA)-based thermal enzyme-linked immunoassay, TELISA, was developed for the rapid detection of atrazine (ATZ) in tap water. ATZ and β-lactamase-labeled ATZ were employed in a competitive immunoassay using a monoclonal antibody (mAb). After the off-column liquid-phase competition, the mAb was captured on the Protein G Sepharose™ 4 Fast Flow (PGSFF) column support material. Injected β-lactamase substrate ampicillin was degraded by the column-bound ATZ-β-lactamase, generating a detectable heat signal. Several assay parameters were optimized, including substrate concentration, flow rates and regeneration conditions, as well as the mAb and ATZ-β dilution ratios and concentrations. The assay linear range was 0.73-4.83 ng mL(-1) with a detection limit of 0.66 ng mL(-1). An entire heat signal requires 10 min for generation, and the cycle time is less than 40 min. The results were reproducible and stable. ATZ-spiked tap water samples exhibited a recovery rate of 103%-116%, which correlated with the UHPLC-MS/MS measurements. We attributed this significant increase in sensitivity over our previously published work to the following factors: (i) the capture of already-formed immune complexes on the column via immobilized Protein G, which eliminated chemical immobilization of the antibody; (ii) off-column preincubation allows the formation of immune complexes under nearly ideal conditions; and (iii) multiple buffers can be used to, in one case, enhance immune-complex formation and in the other to maximize enzymatic activity. Furthermore, the scheme creates a universal assay platform in which sensing is performed in the off-column incubation and detection after capture in the enzyme thermistor (ET) detector, which opens up the possibility of detecting any antigen for which antibodies were available.