Special Bacterial Dyes

Ruthenium red (Ammoniated ruthenium oxychloride) is a polycationic dye widely used for electron microscopy (EM) of cells, tissues and vegetative bacteria. Ruthenium red strongly reacts with phospholipids and fatty acids and binds to acidic mucopolysaccharides. Ruthenium red is a L-type calcium current (I_Ca) blocker.

Auramine O is a yellow fluorescent dye. Auramine O is used to detect amyloid fibrils. Auramine O promotes lung malignancy. Auramine O is also used to determine algal cell viability and stain acid-fast bacteria.

Propidium monoazide is a cell-impermeant photoreactive DNA-binding dye that preferentially binds to dsDNA. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the PCR. PMA-PCR enhanced both the specificity and the sensitivity of PCR. Propidium monoazide is a click chemistry reagent, it contains an Azide group and can undergo copper-catalyzed azide-alkyne cycloaddition reaction (CuAAc) with molecules containing Alkyne groups. It can also undergo strain-promoted alkyne-azide cycloaddition (SPAAC) reactions with molecules containing DBCO or BCN groups.

CDy11 is a fluorescent probe and amyloid-binding dye (λ_ex=590 nm; λ_em=612 nm), with a K_a of 29 μM for Pseudomonas aeruginosa Fap. CDy11 specifically recognizes amyloid fibrils in bacterial biofilms and exhibits significantly enhanced fluorescence upon binding to the target. CDy11 shows no staining effect on amyloid-deficient mutant strains, planktonic cells or protein monomers. CDy11 supports in vivo imaging of Pseudomonas aeruginosa biofilms in mouse implant and corneal infection models. CDy11 is widely used in studies of Staphylococcus aureus biofilm infections, dental caries, and Pseudomonas aeruginosa-associated implant and corneal infections.

CDr15 is a deep-red fluorescent probe (Ex=733 nm) that can selectively intercalate into and label bacterial extracellular DNA (eDNA). CDr15 exhibits extremely high specificity for biofilm imaging and cannot effectively bind to mammalian nuclear DNA. CDr15 enables real-time visualization of the microcolony structure and developmental process of three-dimensional *Pseudomonas aeruginosa* biofilms, and accurately localizes biofilm-forming regions of microorganisms in a mouse corneal infection model. With low background interference signals, CDr15 serves as an ideal diagnostic tool for research fields including bacterial biofilms and corneal infections.

CDy14 is a fluorescent probe targeting the extracellular polysaccharide Psl. CDy14 enables the detection of biofilms. CDy14 can be used for research on chronic bacterial infections.

TBD–anchor is a water-soluble, positively charged AIE photosensitizer. TBD–anchor can specifically bind to bacterial membranes and efficiently produce ¹O₂. TBD–anchor has bactericidal activity against various bacteria and good biocompatibility. TBD–anchor can be used for research on bacterial infections.

BIN-3 is a novel near-infrared fluorescent probe. BIN-3 has excellent biocompatibility, no cytotoxicity, and no hemolysis. BIN-3 can be used for highly sensitive and selective imaging of drug-resistant bacterial infections expressing β-lactam enzymes in live mice.

ARHB is a highly selective and sensitive NAT2 fluorescent probe suitable for real-time detection of NAT2 activity in various bacteria. ARHB can successfully penetrate the bacterial cells, and the fluorescence intensity is positively correlated with the expression level of NAT2. ARHB is used for high-throughput screening of natural inhibitors for tuberculosis.