Overview
Propidium Iodide (PI) is a vital fluorescent dye primarily used in biological research for nucleic acid staining. As a member of the phenanthridinium family, it binds to DNA by intercalating between base pairs, making it particularly valuable for distinguishing between live and dead cells in viability assays. First synthesized in the 1970s, PI gained prominence due to its membrane-impermeant properties, which allow selective staining of cells with compromised membranes (a hallmark of dead or dying cells). This characteristic, combined with its strong red fluorescence when bound to DNA, has made it indispensable in flow cytometry and microscopy applications.
Physical and Chemical Properties
PI appears as a dark red crystalline powder with good solubility in aqueous solutions (typically used at 1-50 μg/mL concentrations). Its fluorescence properties are highly concentration-dependent, exhibiting excitation/emission maxima at 535/617 nm when bound to DNA. Chemically, PI is stable when stored properly but degrades upon prolonged exposure to light. The dye shows preferential binding to double-stranded DNA (with approximately 20-fold greater affinity than for RNA), with each PI molecule occupying about 4-5 base pairs. Its fluorescence quantum yield increases nearly 20-fold upon nucleic acid binding, providing excellent signal-to-noise ratios in biological assays.
Main Applications
In cell biology, PI serves as a standard marker for dead cells in viability assays, often combined with membrane-permeable dyes like FDA or calcein-AM. Its inability to cross intact plasma membranes makes it ideal for distinguishing between live (PI-negative) and dead (PI-positive) cell populations. Flow cytometry applications utilize PI for DNA content analysis (cell cycle studies) and apoptosis detection. In microscopy, PI counterstaining helps visualize nuclear morphology in fixed tissues. Recent developments include its use in comet assays for DNA damage assessment and in combination with Annexin V for early apoptosis detection.
Safety and Storage
As a potential mutagen, PI requires careful handling with appropriate personal protective equipment (gloves, lab coat, eye protection). Work should be conducted in a fume hood when handling powder form, and all waste should be disposed as hazardous biological material. For storage, PI solutions are light-sensitive and should be kept in amber vials at 2-8°C. Dry powder remains stable for years when stored desiccated and protected from light. Ready-to-use solutions typically maintain stability for several months when refrigerated, though users should check for precipitation or color changes before use.
B2B Procurement Guide
When sourcing PI dye, buyers should specify required purity (typically ≥95% for research applications) and request certificates of analysis. Bulk purchases (gram quantities) often offer better pricing but require verification of solubility and fluorescence performance. Consider supplier reliability, especially for time-sensitive experiments, as supply chain disruptions can occur. Many manufacturers offer pre-made staining solutions (with RNase) for convenience. For regulatory compliance, ensure the supplier provides complete documentation including MSDS, analytical reports, and where applicable, GMP certification for clinical-grade material.
Related Manufacturers
- 主营：生化试剂、蛋白与免疫、ELISA、生化试剂盒、染色试剂、微生物培养、感受态、细胞检测、抗体、抑制剂、助溶剂、分析对照品、标准品、蛋白预制胶、免疫组化、缓冲液、培养基、分离液、磁珠
- 主营：催化剂、peg试剂、cy5四氮、活性脂、苯二胺、2406-34-0、乙氧基、试剂cas、环辛烯、生物素、cb-cyclam、实验室、dbco-acid、半乳糖、溴苯基、交联剂、环己炔、荧光素、3694-51-7、ac4galnal、2001-96-9、葡萄糖、环辛炔、直发cas、糖化学
- 主营：荧光探针、转染试剂、试剂盒、荧光染料、核酸荧光染料、胎牛血清、抽提试剂、萤光素钠盐、萤光素钾盐、抗荧光淬灭剂
- 主营：捕收剂、液体聚硫橡胶、扩链剂、染料中间体、催化剂、交联剂、稳定剂、辅助剂、中间体、碳酸镍、抗氧化剂、乙酰丙酮锰、羟基保护剂、表面活性剂、四甲基氯化铵、分子筛模板剂、溶剂型防锈漆、四乙基氯化铵、正癸基硫酸钠、药物合成原料、氧化石蜡皂、水杨羟肟酸、阻聚剂706、克利夫酸
- 主营：加帽酶、激活剂、甘氨酸、即用型细胞核荧光染料、igg抗体、稳定液、玻璃板、试剂盒、脂蛋白、超纯水、激动剂、胆固醇、盐酸盐、因质粒、扩容剂、组化笔、驴抗人、预制胶、驴抗兔、生物驴、草甘膦、重组酶、生物素、曲拉通、去除剂、封闭液
- 主营：环氧环己烷、异丙叉丙酮、四甲基氢氧化铵、双乙烯酮、均苯四甲酸二酐、三聚甲醛、氯甲基三氯硅烷、双季戊四醇、五水合四甲基氢氧化铵、月桂酸钠、二苯甲酮、聚硫橡胶、邻氯溴苯、水杨羟肟酸、甲基纤维素、甲基丙烯酸十八酯、氨基磺酸、硫氢化钠、甲基磺酸、吐温、司盘、芥酸pko、pko-e
- 主营：荧光染料、花青素染料