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Ruebner, A.; Kirsch, Dieter; Andrees, Sonja; Decker, W.; Roeder, Beate; Spengler, Bernhard; Kaufmann, R.; Moser, Joerg G.

doi:10.1023/a:1007942308945

Cited by 18 publications

(4 citation statements)

References 23 publications

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“…The double reciprocal plot of change in fluorescent intensity and BNS concentration gives straight lines (for an example of such a plot, see Figure ). The straight lines found for each run show that the dimer and BNS were forming 1:1 complexes …”

Section: Resultsmentioning

confidence: 95%

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Cyclodextrin Dimers as Cleavable Carriers of Photodynamic Sensitizers

et al. 2001

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Several phthalocyanines carrying hydrophobic components have been synthesized and shown to bind to a group of cyclodextrin dimers with a carbon-carbon double bond in the linker. The complexes are soluble in water. On irradiation in the presence of oxygen, the singlet oxygen produced cleaves the olefinic linkers in the complexes, resulting in precipitation of the sensitizers. This process concentrates the sensitizers in the light beam, a process that has useful potential in photodynamic therapy.

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Section: Resultsmentioning

confidence: 95%

“…The straight lines found for each run show that the dimer and BNS were forming 1:1 complexes 1 Determination of binding constant for dimer 21 with BNS and phthalocyanine 13 . …”

Section: Resultsmentioning

confidence: 99%

Cyclodextrin Dimers as Cleavable Carriers of Photodynamic Sensitizers

et al. 2001

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“…Table 1 contains a remarkable set of data for this native CD and introduces a new and orthogonal host–guest anchor motif (γ-CD⋅B 12 X 12 2− ). Until now, even association constants on the order of 10 3 L mol −1 have been fairly difficult to achieve for γ-CD,[ 2b ,[ c , 12 ] because its large cavity lacks the high-energy water content which assists the binding to smaller cavities. [ 1c The values observed for the halogenated dianions and γ-CD even rival and exceed the values found for β-CD, the putative highest-affinity host among native CD homologues.…”

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confidence: 99%

Water Structure Recovery in Chaotropic Anion Recognition: High‐Affinity Binding of Dodecaborate Clusters to γ‐Cyclodextrin

et al. 2015

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Dodecaborate anions of the type B12X122− and B12X11Y2− (X=H, Cl, Br, I and Y=OH, SH, NH3+, NR3+) form strong (Ka up to 106 L mol−1, for B12Br122−) inclusion complexes with γ-cyclodextrin (γ-CD). The micromolar affinities reached are the highest known for this native CD. The complexation exhibits highly negative enthalpies (up to −25 kcal mol−1) and entropies (TΔS up to −18.4 kcal mol−1, both for B12I122−), which position these guests at the bottom end of the well-known enthalpy-entropy correlation for CDs. The high driving force can be traced back to a chaotropic effect, according to which chaotropic anions have an intrinsic affinity to hydrophobic cavities in aqueous solution. In line with this argument, salting-in effects revealed dodecaborates as superchaotropic dianions.

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“…Another problem has to do with the desirability of localizing the photosensitizer at the tumor site to prevent unwanted side reactions elsewhere. An approach to the latter problem has been to target the photosensitizer by using cancerspecific antibodies (3), but this use of a foreign protein may not be ideal.…”

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confidence: 99%

A cyclodextrin dimer with a photocleavable linker as a possible carrier for the photosensitizer in photodynamic tumor therapy

Ruebner

Yang

Leung

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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A cyclodextrin dimer has been synthesized with two ␤-cyclodextrins linked by a flexible chain containing a carbon-carbon double bond. This dimer binds and solubilizes a phthalocyanine-based photosensitizer that generates singlet oxygen on irradiation. When the complex is irradiated, the singlet oxygen cleaves the carbon-carbon link, and the cyclodextrins are released, liberating the photosensitizer into the light path. Ideas about how this phenomenon could be used to make photodynamic tumor therapy into a more selective process are described. In photodynamic therapy, a dye such as a porphyrin or a phthalocyanine is used in conjunction with irradiation, e.g., by visible light. The excited-state dye converts triplet oxygen to the singlet, which is lethal to cells. Light directed into the area of a tumor can lead to the destruction of cancer cells (1, 2). One problem in this field is of course the accessibility of tumors to irradiation. Another problem has to do with the desirability of localizing the photosensitizer at the tumor site to prevent unwanted side reactions elsewhere. An approach to the latter problem has been to target the photosensitizer by using cancerspecific antibodies (3), but this use of a foreign protein may not be ideal.A different approach has been proposed by Moser et al. (4). If a quite hydrophobic photosensitizer is bound to a cyclodextrin (CD) dimer, the complex will become much more hydrophilic, and the strongly bound sensitizer may not be easily taken up by tissues, including those that are not the target tumor cells. However, if the linker in the CD dimer can be cleaved by singlet oxygen, the photosensitizer should be released from the dimer and then enter nearby cells.If this cleavage occurs in the tumor region that is being irradiated, there should be two results. First of all, cleavage of the CD dimer will deliver the photosensitizer to the affected cells, as proposed by Moser et al. (4). Perhaps more interestingly, the destruction of the dimer-sensitizer complex by light will cause more of it to diffuse into the irradiated region, concentrating the sensitizer where it is needed. In other words, the sensitizer will be concentrated into the directed light beam.We have tested this concept by using an electron-rich carboncarbon double bond as the group that is cleavable by singlet oxygen. The oxygen adds to the double bond to form a dioxetane, which fragments to form two carbonyl groups (5). Sulfur substituents at each end of the double bond increase its reactivity. Materials and MethodsCD dimer 1 was synthesized by conversion of cystamine to its N-t-butoxycarbonyl derivative, then reduction of the disulfide link with sodium in ammonia and reaction of the thiolate with cis-1,2-dichloroethylene to form 2 (Scheme 1). All compounds were characterized by NMR and MS, and this olefin 2 had the characteristic infrared signal at 627 cm Ϫ1 for a cis double bond. Acid deprotection of 2 and then acylation with iodoacetic acid anhydride afforded a bis-iodide that was converted to a bisthioacetate. ...

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Cited by 18 publications

References 23 publications

Cyclodextrin Dimers as Cleavable Carriers of Photodynamic Sensitizers

Cyclodextrin Dimers as Cleavable Carriers of Photodynamic Sensitizers

Water Structure Recovery in Chaotropic Anion Recognition: High‐Affinity Binding of Dodecaborate Clusters to γ‐Cyclodextrin

A cyclodextrin dimer with a photocleavable linker as a possible carrier for the photosensitizer in photodynamic tumor therapy

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