The DP5 Probability, Quantification and Visualisation of Structural Uncertainty in Single Molecules

Whenever a new molecule is made, a chemist will justify the proposed structure by analysing the NMR spectra. The widely-used DP4 algorithm will choose the best match from a series of possibilities, but draws no conclusions from a single candidate structure. Here we present the DP5 probability, a step-change in the quantification of molecular uncertainty: given one structure and one 13C NMR spectra, DP5 gives the probability of the structure being correct. We show the DP5 probability can rapidly differentiate between structure proposals indistinguishable by NMR to an expert chemist. We also show in a number of challenging examples the DP5 probability may prevent incorrect structures being published and later reassigned. DP5 will prove extremely valuable in fields such as discovery-driven automated chemical synthesis and drug development. Alongside the DP4-AI package, DP5 can help guide synthetic chemists when resolving the most subtle structural uncertainty. The DP5 system is available at https://github.com/Goodman-lab/DP5.

Dynamic single-molecule sensing via nanoparticle micromanipulation for rapid and ultrasensitive biomarker detection

The ability to measure many single molecules simultaneously in larger and complex samples is critical to the translation of single-molecule sensors for practical applications in biomarker detection. The challenges lie in the limits imposed by mass transportation and thermodynamics, resulting in long assay time and/or insufficient sensitivity. Here, we report an approach called Sensing Single Molecule under MicroManipulation (SSM3) to circumvent the above limits. In SSM3, the transportation rate of analyte molecules and the kinetics of molecular interaction are fine-tuned by the nanoparticle micromanipulation. The heterogeneous lifetime of molecular complexes is quantified to discriminate specific binding from nonspecific background noise. By the highly-specific digital counting of single molecules, we demonstrate 15-minute assays for direct detection of microRNAs and amyloid-β proteins via electrical or magnetic micromanipulation, with the limit of detection at the subfemtomolar level. The presented approach could inspire more practical applications of single molecule sensors.