DiBAC4(3)

DiBAC4(3) is a negatively charged membrane potential-sensitive bis-oxonol dye with excitation maxima at approximately 490nm and its fluorescence emission is collected using a 520nm filter^[1]. DiBAC4(3) is a versatie tool in membrane potential monitoring, viability assays and antibiotic susceptibility testing.

In vitro, DiBAC4(3) was used to measure membrane potentials in HEK293 cells expressing recombinant large conductance Ca²⁺-activated K⁺ (BK) channels (HEKBKα and HEKBKβ ). Cells were incubated in KRH (Krebs-RingerHEPES) buffer containing with 100nM DiBAC4(3) for 20min at room temperature. The oscillatory membrane hyperpolarization induced in HEKBKαβ by was detected only as a slow hyperpolarization with DiBAC4(3)^[2]. B. subtilis cells incubated with membrane-targeting antimicrobials were stained with 10μM DiBAC4(3) for 17h and observed under phase contrast and fluorescence microscopy to evaluate the effects of antimicrobial compounds on membrane integrity and function^[3]. DiBAC4(3) (1μM) was used to assess cell viability and membrane potential in starved cultures of E. coli and Salmonella in seawater. Cells may maintain some membrane potential, they do not necessarily exhibit active respiration, especially in starved conditions^[4].

References:
[1] Epps D E, Wolfe M L, Groppi V. Characterization of the steady-state and dynamic fluorescence properties of the potential-sensitive dye bis-(1,3-dibutylbarbituric acid)trimethine oxonol (Dibac4(3)) in model systems and cells. Chem Phys Lipids. 1994 Feb;69(2):137-50.
[2] Yamada A, Gaja N, Ohya S,et al. Usefulness and limitation of DiBAC4(3), a voltage-sensitive fluorescent dye, for the measurement of membrane potentials regulated by recombinant large conductance Ca₂₊-activated K+ channels in HEK293 cells. Jpn J Pharmacol. 2001 Jul;86(3):342-50.
[3] Winkel J D T, Gray D A, Seistrup K H. Analysis of Antimicrobial-Triggered Membrane Depolarization Using Voltage Sensitive Dyes. Front Cell Dev Biol. 2016 Apr 13:4:29.
[4] Amorós R L, Castel S, Riu J C, Rego J V. Assessment of E. coli and Salmonella viability and starvation by confocal laser microscopy and flow cytometry using rhodamine 123, DiBAC4(3), propidium iodide, and CTC. Cytometry. 1997 Dec 1;29(4):298-305.

DiBAC4(3)是一种带负电荷的膜电位敏感型双氧杂蒽染料，其激发最大值约为490纳米，荧光发射通过520纳米的滤光片收集^[1]。DiBAC4(3)是一种多功能的工具，可用于膜电位监测、细胞活性检测以及抗生素敏感性测试。

在体外实验中，DiBAC4(3)被用于测量表达重组大电导钙激活钾通道（BK通道）的HEK293细胞的膜电位（包括HEKBKα和HEKBKβ）。在室温下将细胞在含有100nM DiBAC4(3)的KRH（Krebs-Ringer-HEPES）缓冲液中孵育20min进行染色，在HEKBKαβ中诱导产生的振荡性膜超极化被DiBAC4(3)检测为缓慢的超极化^[2]。将枯草芽孢杆菌细胞与不同膜靶向抗菌药物一起孵育后，用10μM DiBAC4(3)染色17h，并在相差显微镜和荧光显微镜下观察，以评估抗菌化合物对膜完整性和功能的影响^[3]。用1μM DiBAC4(3)来评估大肠杆菌和沙门氏菌在海水饥饿培养中的细胞活性和膜电位。细胞可能维持一定的膜电位，但它们不一定表现出活跃的呼吸作用^[4]。