Synthesis and DNA binding profile of monomeric, dimeric, and trimeric derivatives of crystal violet.

Monomeric, dimeric, and trimeric derivatives of the triphenylmethane dye crystal violet (1a-1f) have been synthesized for the purpose of evaluating their affinity and sequence selectivity for duplex DNA. Competitive ethidum displacement assays indicate that 1a-1f have apparent association constants for CT DNA in the range of 1.80-16.2 × 107 M-1 and binding site sizes of 10-14 bp. Viscosity experiments performed on ligand 1f confirmed that these dyes associate with duplex DNA by a non-intercalative mode of binding. Circular dichroism and competition binding studies of the tightest binding ligand 1e with known major and minor groove binding molecules suggest that these dye derivatives likely occupy the major groove of DNA. Data from the binding of 1e to polynucleotides indicate close to an order of magnitude preference for associating with AT rich homopolymers over GC rich homopolymers, suggesting a shape-selective match of the sterically bulky ligand with DNA containing a wider major groove.

A magnetic Gram stain for bacterial detection.

Magnetizing: Bacteria are often classified into gram-positive and gram-negative strains by staining with crystal violet (CV). The described bioorthogonal modification of CV with trans-cyclooctene (TCO) can be used to render gram-positive bacteria magnetic with tetrazine-functionalized magnetic nanoparticles (MNP-Tz). This method allows class-specific automated magnetic detection and magnetic separation.