Embodiments of the present disclosure are directed to methods, systems and devices, for analyzing the molecules. For example, in some embodiments, a system is provided which includes a first volume of conducting fluid, a second volume of conducting fluid, an orifice in communication with the first and second volumes of fluid, and means for applying an electric potential difference between the first and second volumes of fluid. In some such embodiments, a conjugate product is provided which comprises charged polymers each having attached thereto at least one first molecule for analysis, where the product carries a predetermined charge greater than the charge on the first molecule, and upon dissolving the product in the first volume of fluid, the product is directed into the orifice.

The invention describes methods and reagents useful for sequencing polypeptide molecules. The method comprises affixing a polypeptide to a substrate and contacting the polypeptide with a plurality of probes. Each probe selectively binds to an N-terminal amino acid or an N-terminal amino acid derivative. Probes bound to the polypeptide molecule are then identified before cleaving the N-terminal amino acid or N-terminal amino acid derivative of the polypeptide. Also provided are methods for the sequencing a plurality of polypeptide molecules in a sample and probes specific for N-terminal amino acids or N-terminal amino acid derivatives.

Provided herein, inter alia, are single chain antibody binding domains (VHHs) for use in conjunction with the Assay with a Large Immuno-sorbent Surface Area (ALISSA). Engineered and affinity matured VHHs are used as affinity reagents in the ALISSA resulting in an exceptionally sensitive and precise method for the detection of toxins at miniscule concentrations. Thus, provided herein are methods as well as reagents that can be used to detect the presence of botulinum neurotoxins in quantities well below 1 pg/mL which corresponds to a lethal concentration under presumed equal distribution throughout the human body.

Cells are described that are useful in rapid, sensitive, and accurate cell-based assays for enzyme activity, particularly for enzyme activities associated with botulinum toxins. Such cell expresses a construct that includes an anchor region, a cleavage site, and a reporting region having two or more identical reporter peptides. Enzymatic activity at the cleavage site releases the reporter region into the cytosol of the cell, where multiple degradation events occur. The observed change in the signal is proportional to the enzymatic activity.

Compositions and methods are provided that improve detection of botulinum neurotoxins in cell-based assays. In one aspect an isoquinolynyl compound can be used to enhance the sensitivity of both Frster resonance energy transfer (FRET) and non-FRET cell-based assays. Osmolarity of the cell culture media can be adjusted to optimize the effect of the compound. In that subject matter an environment cell can include an enzyme that facilitates degradation of the reporter significantly faster after the cleavage than before the cleavage, and presence of the Botulinum toxin correlates with reduction of the signal from a baseline signal. Where the environment is a cell, the cell can advantageously express both the construct that includes the reporter, and an enzyme that facilitates the degradation.

The present specification discloses a retargeted endopeptidase pharmaceutical wherein the activity has been determined by the methods disclosed.

Methods and compositions for detecting BoNT/A enzymatic activity in tissues or a tissue sample are described herein. The invention encompasses antibodies that bind preferentially to BoNT/A cleaved SNAP25 and is able to preferentially detect BoNT/A cleaved SNAP25, as compared to intact (non-cleaved) SNAP25, in a tissue sample.

There is provided a biosensor for detecting pathogens in a sample. The detection is based on colorimetry. The biosensor comprises one or more particle supports and a magnetic material attached to a planar support. The biosensor embodies magnetic particles that are functionalized using a chemical substrate specific to the pathogens to be detected. The sensor may allow for a simultaneous detection of a plurality of pathogens in the sample. Also, the sensor may be disposable. Moreover, the sensor may be integrated in a portable detection device.

The present invention relates to peptide substrates selectively recognized by botulinum toxin type A, BoNT/E, and their uses, in particular for carrying out methods for detecting, identifying and/or diagnosing botulinum toxin type E.

The present invention concerns rhodamine based fluorescent probes which have use in detecting coagulase-producing bacterial strains. In particular, wherein the bacterial strain is MRSA or MSSA.