Enhanced aqueous solubility of long wavelength voltage-sensitive dyes by covalent attachment of polyethylene glycol
作者:Michael J. Patrick、Lauren A. Ernst、Alan S. Waggoner、Dung Thai、Dean Tai、Guy Salama
DOI:10.1039/b711438a
日期:——
Long wavelength voltage-sensitive dyes (VSDs) called Pittsburgh (PGH) dyes were recently synthesized by coupling various heterocyclic groups to a styryl-thiophene intermediate forming extended, partially rigid chromophores. Unlike most styryl VSDs, dyes with a sulfonic acid anchor directly attached to the chromophore showed no solvatochromic absorption shifts. The limited water solubility of many long wavelength VSDs requires the use of surfactants to transport the dye through physiological saline solutions and effectively label biological membranes. Here, we tested the chemical substitution of the sulfonic acid moiety with polyethyleneglycol (PEG) chains, ranging from MW 750 to 5000, to overcome the poor solubility of VSDs while retaining their properties as VSDs. The chemical synthesis of PGH dyes and their PEG derivatives are described. The PEG derivatives were soluble in aqueous solutions (>1 mM) and still reported membrane potential changes. In frog and mouse hearts, the voltage sensitivity (ΔF/F per action potential) and spectral properties of PEG dyes were the same as the sulfonated analogues. Thus, the solubility of VSDs can be considerably improved with small polyethyleneglycol chains and can provide an effective approach to improve staining of excitable tissues and optical recordings of membrane potential.
长波长电压敏感染料(VSDs),称为匹兹堡(PGH)染料,最近通过将各种杂环基团与苯乙烯硫苯中间体耦合形成扩展的、部分刚性的发色团而合成。与大多数苯乙烯类VSDs不同,具有直接连接到发色团的磺酸酸锚的染料没有显示出溶剂化变色吸收位移。许多长波长VSDs的有限水溶性需要使用表面活性剂以通过生理盐水溶液运输染料并有效地标记生物膜。在此,我们测试了将磺酸基团与聚乙二醇(PEG)链进行化学替代,分子量从750到5000不等,以克服VSDs的差溶解性,同时保留它们的VSD特性。描述了PGH染料及其PEG衍生物的化学合成。PEG衍生物在水溶液中可溶(>1 mM)并且仍然能够报告膜电位变化。在青蛙和小鼠心脏中,PEG染料的电压敏感性(每个动作电位的ΔF/F)及其光谱特性与磺化类似物相同。因此,可以通过小的聚乙二醇链显著改善VSDs的溶解性,并提供一种有效的方法来改善易兴奋组织的染色和膜电位的光学记录。