Facial amphiphiles in molecular recognition: From unusual aggregates to solvophobically driven foldamers

Zhao, Yan

doi:10.1016/j.cocis.2007.05.001

Cited by 46 publications

(25 citation statements)

References 57 publications

(39 reference statements)

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“…The molecular structure of bile acid is considerably different from conventional surfactants and the mechanism of their formation is quite complex, often involving complicated "secondary assemblies". [15] As mentioned above, the spectroscopy studies (UV/Vis, CD, and fluorescence) demonstrate that OPE-derived steroidal compounds undergo extensive conformational changes in solvent/nonsolvent (THF/ water) mixtures. It is believed that the cooperation of aromatic stacking, hydrogen bonding, and van der Waals interactions contributes significantly to the observed unique mesoscopic structures, whereas the orientation of the chromophore plays a crucial role in the optical and chiroptical properties.…”

Section: Mechanism Of Self-assemblymentioning

confidence: 89%

Unique Twisted Ribbons Generated by Self‐Assembly of Oligo(p‐phenylene ethylene) Bearing Dimeric Bile Acid Pendant Groups

Wang

et al. 2009

Chemistry A European J

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Let's twist again! Remarkable broad and twisted ribbons were generated from the self-assembly of oligo(p- phenylene ethylene) (OPE) bearing dimeric deoxycholic acid pendant groups (see graphic). Varying the bile acid led to nanostructures with drastically different morphologies. The distinctive aggregate shapes of these steroid-OPE conjugates are attributed to the subtle differences in their molecular structures.A series of novel oligo(p-phenylene ethynylene) (OPE) derivatives bearing dimeric cholic acid (OPE1), deoxycholic acid (OPE2) and lithocholic acid (OPE3) was synthesized. The self-assembly behavior of these derivatives were systematically studied and compared in a THF/water solvent mixture. The addition of water to THF can induce the helical stacking of oligo(p-phenylene ethylene) bearing dimeric deoxycholic acid end groups, which leads to highly interesting twisted assemblies. Variation of the bile acid group led to nanostructures with drastically different morphologies. The application of spectroscopy in combination with X-ray diffraction techniques provided a reasonable view of the final self-assembled structures. The observed distinctive aggregate shapes and the preference in the type of molecular packing of these steroid-OPE conjugates are attributed to the subtle differences in their molecular features.

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Section: Mechanism Of Self-assemblymentioning

confidence: 89%

Unique Twisted Ribbons Generated by Self‐Assembly of Oligo(p‐phenylene ethylene) Bearing Dimeric Bile Acid Pendant Groups

Wang

et al. 2009

Chemistry A European J

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“…16−20 This Feature Article summarizes our recent efforts in polymerizing/cross-linking surfactant micelles and converting them into multifunctional nanoparticles. Our surface-cross-linked micelles (SCMs) can be tuned in multiple ways including surface functionality, internal content, and water or oil solubility.…”

Section: Introductionmentioning

confidence: 99%

Surface-Cross-Linked Micelles as Multifunctionalized Organic Nanoparticles for Controlled Release, Light Harvesting, and Catalysis

Zhao

2016

Langmuir

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Surfactant micelles are dynamic entities with a rapid exchange of monomers. By “clicking” tripropargylammonium-containing surfactants with diazide cross-linkers, we obtained surface-cross-linked micelles (SCMs) that could be multifunctionalized for different applications. They triggered membrane fusion through tunable electrostatic interactions with lipid bilayers. Antenna chromophores could be installed on them to create artificial light-harvesting complexes with efficient energy migration among tens to hundreds of chromophores. When cleavable cross-linkers were used, the SCMs could break apart in response to redox or pH signals, ejecting entrapped contents quickly as a result of built-in electrostatic stress. They served as caged surfactants whose surface activity was turned on by environmental stimuli. They crossed cell membranes readily. Encapsulated fluorophores showed enhanced photophysical properties including improved quantum yields and greatly expanded Stokes shifts. Catalytic groups could be installed on the surface or in the interior, covalently attached or physically entrapped. As enzyme mimics, the SCMs enabled rational engineering of the microenvironment around the catalysts to afford activity and selectivity not possible with conventional catalysts.

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“…Cholic acid is a unique facial amphiphilic molecule displaying two methyl groups and three hydroxyl groups on two opposite faces of a rigid polycyclic steroidal scaffold with one carboxyl group at one end for covalent ligation. These features make cholic acid an excellent building block for constructing functionalized molecular architectures with well-defined geometrical properties as well as molecular container for host-guest chemistry [19, 20]. Ebes linkers were introduced as an inert hydrophilic spacer molecule [18] within the oligo-lysine backbone to provide flexibility and to reduce the steric hindrance caused by the bulky cholic acids.…”

Section: Introductionmentioning

confidence: 99%

A novel size-tunable nanocarrier system for targeted anticancer drug delivery

Xiao

Luo

et al. 2010

Journal of Controlled Release

116

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We have developed a nanocarrier drug-delivery system based on micelles formed by a new class of well-defined linear PEGylated two-arm oligomer of cholic acids in aqueous solution. By varying the length of the linear PEG chains and the configuration of cholic acid oligomer, one can easily finetune the physicochemical properties of the amphiphilic polymers and the resulting micelles. These include particle size, critical micelle concentration, and drug loading capacity. High level of hydrophobic anticancer drugs such as PTX, etoposide and SN-38 can be readily loaded into such nanocarriers. The loading capacity of the nanocarrier for PTX (PTX) is extremely high (12.0 mg/ mL), which is equivalent to 37.5% (w/w) of the total mass of the micelle. PTX-loaded nanocarriers are much more stable than Abraxane® (PTX/human serum albumin nanoaggregate) when stored in bovine serum albumin solution or dog plasma. PTX release profile from the micelles is burst-free and sustained over a period of seven days. The anti-tumor activity of PTX-loaded nanocarriers against ovarian cancer cell line in vitro, with continuous drug exposure, is similar to Taxol® (formulation of PTX dissolved in Cremophor EL and ethanol) or Abraxane®. Targeted drug delivery to tumor site with these novel micelles was demonstrated by near infrared fluorescence (NIRF) imaging in nude mice bearing ovarian cancer xenograft. Furthermore, PTX-loaded nanocarriers demonstrated superior anti-tumor efficacy compared to Taxol® at equivalent PTX dose in ovarian cancer xenograft model.

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Facial amphiphiles in molecular recognition: From unusual aggregates to solvophobically driven foldamers

Cited by 46 publications

References 57 publications

Unique Twisted Ribbons Generated by Self‐Assembly of Oligo(p‐phenylene ethylene) Bearing Dimeric Bile Acid Pendant Groups

Unique Twisted Ribbons Generated by Self‐Assembly of Oligo(p‐phenylene ethylene) Bearing Dimeric Bile Acid Pendant Groups

Surface-Cross-Linked Micelles as Multifunctionalized Organic Nanoparticles for Controlled Release, Light Harvesting, and Catalysis

A novel size-tunable nanocarrier system for targeted anticancer drug delivery

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