Synthesis, spectroscopic properties and protein labeling of water soluble 3,5-disubstituted boron dipyrromethenes

Abstract

Sulfur-containing 3,5-disubstituted boron dipyrromethene (Bodipy®) fluorescent probes with improved water solubility were synthesized. A dicarboxylic acid derivative that can be excited by the 543 nm HeNe laser line is very soluble in aqueous solution and retains high fluorescence quantum yield of the unionizable parent molecule. Conversion of the dicarboxylic acid to the succimidyl or sulfosuccinimidyl diester produces molecules capable of labeling proteins with a bright and stable fluorescence signal.Boron dipyrromethene fluorophores (Bodipy ® or BDP) are widely used as probes in biological systems. 1 These molecules normally have good photostability and high quantum yields, 2, 3 but they tend to have low aqueous solubility. 4 The absorption and emission maxima can be tuned to chosen regions of the visible to the near-IR region of the electromagnetic spectrum by varying the substituents on the dipyrromethene chromophore. 5-9 Lowering the energy of the absorption maximum often involves addition on unsaturated or aromatic systems, 10, 11 which decreases their aqueous solubility, thereby limiting their utility as biological probes.Recently efforts have been made to increase the aqueous solubility of BDPs. Burgess' group has shown that addition of a sulfonate group to the 2-and 6-positions increases aqueous solubility without sacrificing quantum yield. 4 They have also made water soluble BDPs for covalent modification of biomolecules and cassettes for energy transfer by appending sulfonic acids to the BDP core and adding carboxylic acid-containing tethers. 12, 13 Niu et al. have taken a different approach. They attached hydrophilic molecules containing multiple ionizable groups to various positions on the parent molecule. 14,15 In some cases aqueous concentrations of 100 -750 μM could be obtained.The objective of this work was to make BDP derivatives that fluoresce at long wavelength, are soluble in aqueous solution and can be used for protein labeling. The molecules are based on the 3,5-disubstituted BDP's of Rohand et al., 9 which are easy to synthesize and whose absorption and emission maxima can be tuned by altering the nature of the functional group. 16,17 The sulfur-substituted compounds possessed the best properties for this type of label: absorption maximum near the HeNe 543 nm line and good quantum yield in both polar and apolar environments. 13,18 Reported here is the synthesis and characterization of water soluble BDPs suitable for biological applications. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Syntheses of the 3,5-substituted BDPs are presented ...

Structural modification strategies for the rational design of red/NIR region BODIPYs

“…This represents a bottleneck that impedes further progress in biomedical analysis. To date, although a few water-soluble BODIPY derivatives have been prepared by introducing oligo-(ethyleneglycol) chains, [351][352][353][354][355] nucleotides, 356 sulfonated peptides, [357][358][359] carboxylates, [360][361][362][363][364][365][366][367] sulfonates, [363][364][365][366][367][368][369][370] phosphonate 371 or betaine moieties, 372 there has been only limited progress where the preparation of p-extended dyes emitting in the 650-850 nm window is concerned. In most cases, solubility is achieved by linking a polar group such as a negatively charged sulfonate to the dye.…”

Structure Based Modulation of Electron Dynamics in meso-(4-Pyridyl)-BODIPYs: A Computational and Synthetic Approach

“…The first report of a small water-soluble BODIPY was by Wories et al in 1985, which used sulfonate groups to solubilize the fluorophore, but by 2007 only a handful of water-soluble BODIPYs had been reported . Since then, the main strategy used for water solubilization of BODIPY derivatives consists of the introduction of water-solubilizing groups, particularly at the boron center, including polyethylene glycols, ,− hydroxyls and ethers, − amines, sulfonamides, carboxylates, ,,,− sulfonates, ,− phosphonates, − quaternary ammonium salts, ,,,,, carbohydrates, − and peptides. , Most of these groups increase the size of the dye, decrease its stability, , or utilize negative charges which tend to decrease the cell membrane permeability. However, cationic dyes such as rhodamine and (poly)­cationic porphyrins are able to electrostatically interact with the negative charges present on cell membranes, increasing their permeability.…”

Synthesis and Mechanism Study of 3-Morpholin Boron- dipyrrolemethene Derivatives

“…对 8-苯系 BODIPY 类化合物(图 1)的 BODIPY 母体 进行不同的修饰, 可以使此类化合物具有不同的光学性 能. 目前, 主要采用的方法是在 BODIPY 母体的 α-C [8,9] 或 β-C [10,11] 上 引 入 卤 素 后 再 引 入 修 饰 基 团 来 修 饰 BODIPY 类化合物, 而关于亲核试剂直接取代 BODIPY 母体 3-H 的研究查阅到三篇文献. 由 Wim Dehaen 团队 在强碱的反应环境下, 采用具有易离去基团的亲核试 剂, 运用亲核氢取代反应(VNS)机理, 亲核试剂直接取 代 3-H 生成 BODIPY 衍生物 [12] .…”