Single pathogen Au-nanoprobe detection assays using a MTBC probe; b
Plasmodium sp. probe. The colorimetric assay consists of visual comparison of test solutions after salt induced Au-nanoprobe aggregation. Au-nanoprobes aggregation was measured by ratio of aggregation (ratio of SPR intensity at 525 and 600 nm) for the assay mixtures—2.5 nM Au-nanoprobe, 10 mM phosphate buffer (pH 8) + 0.1 M NaCl, purified dsDNA targets (PCR products) at a final concentration of 60 ng/µL. All spectrophotometric data was collected 30 min after salt addition and error bars represent the standard deviation of three independent assays. The horizontal line represents the threshold of 1 considered for discrimination between positive (rAbs ≥ 1) and negative (rAbs < 1) result. A representative colorimetric results is showed upon each result bar-red positive result; blue/purple negative result.