SYTO9 

SYTO9 is a green fluorescent nucleic acid dye (Ex = 485 nm, Em = 498 nm (DNA)/501 nm (RNA)). SYTO9 can penetrate the intact cell membrane of viable bacteria. When the cell membrane is damaged (cell death), its rate of entry into cells increases, and it competes with propidium iodide (PI) (HY-D0815), another membrane-impermeable dye, for nucleic acid binding sites. SYTO9 is widely used in fluorescence microscopy, flow cytometry, and fluorometric assays in microbiology for bacterial counting, viability assessment, and cell imaging^[1][2][3].

SYTO9 (0.5-1 μM; 5-30 min) staining of Bacillus cereus, Escherichia coli, Salmonella enterica subspecies enterica ser. Typhimurium, and Staphylococcus aureus bacterial suspensions produces species-specific fluorescence intensity that interacts with cell concentration, with no significant effects from 1 mM EDTA or staining duration (5-30 min) or SYTO 9 concentration (0.5 vs. 1 μM) across the tested ranges^[1].
SYTO9 (0.5-1 μM; 5-30 min) in peptone water (cell-free) shows a small but significant increase in fluorescence intensity with concentration (0.5 vs. 1 μM) and no significant effects from 1 mM EDTA or incubation duration (5-30 min)^[1].
SYTO9 (3.34 mM stock in DMSO; 15 min dark incubation post-staining; assessed at 0, 40, 80, 160, 240 min ethanol exposure time points) - PI dual staining identifies live, compromised, and dead populations in Escherichia coli K-12 strain M72 (plucTet) but produces less distinct population separation compared to GFP-PI, with SYTO9 green fluorescence showing up to a 3.9-fold increase under ethanol treatment^[2].
SYTO9 (0.5 μM)-based HRM analysis accurately detects β⁰-thalassemia mutations (codons 17, 41/42, 71/72) and Hb-E in genomic DNA from cultured amniocytes or cord blood cells, with results completely consistent with HPLC analysis of fetal blood^[3].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

460.57

C₂₅H₂₀N₂O₃S₂

854647-88-4

Solid

Brown to red

503

483

O=S([O-])(C1=CC=C2S/C(N(C)C2=C1)=C\C3=CC=[N+](CC4=CC=CC=C4)C5=C3C=CC=C5)=O

Room temperature in continental US; may vary elsewhere.

4°C, protect from light

*In solvent : -80°C, 6 months; -20°C, 1 month (protect from light)

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month (protect from light). When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

• [1]. McGoverin C, et al. Species Dependence of SYTO 9 Staining of Bacteria. Front Microbiol. 2020;11:545419. Published 2020 Sep 3.  [Content Brief]

  [2]. Lehtinen J, et al. Green fluorescent protein-propidium iodide (GFP-PI) based assay for flow cytometric measurement of bacterial viability. Cytometry A. 2004;60(2):165-172.  [Content Brief]

  [3]. Pornprasert S, Sukunthamala K. SYTO9 and SYBR GREEN1 with a high-resolution melting analysis for prenatal diagnosis of β⁰-thalassemia/hemoglobin-E. Eur J Haematol. 2010 Nov;85(5):424-9.
   [Content Brief]