Solvent Effects on the Protonation Constants of Some α-Amino Acid Esters in 1,4-Dioxane–Water Mixtures

Doğan, Alev; Aslan, Nazife; Canel, Esin; Kılıç, Esma

doi:10.1007/s10953-010-9612-z

Cited by 12 publications

(6 citation statements)

References 28 publications

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“…Tw20-ders show similar pKa values but it is well known that the basicity of a compound is a result of various factors such as (i) the solvent effect (solvation power, the tendency of forming hydrogen bonds, selective solvation, dielectric constant and the composition of the solution in the first solvation layer) and (ii) structural effects, electronic effects, and steric effects (Dogan et al 2010).…”

Section: Vesicle Interaction With Cellular Mimetic Membranesmentioning

confidence: 99%

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

Marianecci

Rinaldi

Marzio

et al. 2012

Biomed Microdevices

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Surfactant nanocarriers have received considerable attention in the last several years as interesting alternative to classic liposomes. Different pH-sensitive vesicular colloidal carriers based on Tween 20 derivatives, obtained after functionalization of the head groups of the surfactant with natural, or simply modified, amino acids, were proposed as drug nanocarriers. Dynamic light scattering, Small Angle X-ray Scattering, Trasmission Electron Microscopy and fluorescence studies were used for the physico-chemical characterization of vesicles and mean size, size distribution, zeta potential, vesicle morphology and bilayer properties were evaluated. The pH-sensitivity and the stability of formulations, in absence and in presence of foetal bovine serum, were also evaluated. Moreover, the contact between surfactant vesicles and liposomes designed to model the cellular membrane was investigated by fluorescence studies to preliminary explore the potential interaction between vesicle and cell membranes. Experimental findings showed that physico-chemical and technological features of pH-sensitive vesicles were influenced by the composition of the carriers. Furthermore, proposed carriers are able to interact with mimetic cell membrane and it is reasonable to attribute the observed differences in interaction to the architectural/structural properties of Tween 20 derivatives. The findings reported in this investigation showed that a deep and extensive physico-chemical characterization of the carrier is a fundamental step, according to the evidence that the knowledge of nanocarrier properties is necessary to translate its potentiality to in vitro/in vivo applications.

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Section: Vesicle Interaction With Cellular Mimetic Membranesmentioning

confidence: 99%

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

Marianecci

Rinaldi

Marzio

et al. 2012

Biomed Microdevices

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“…For example, the reported pK a ( + NH) of methyl 2-aminoacetate is ∼7.7. 29,30 The pK a values of the pHP amines 1a−c are about 10, typical of those observed for aliphatic amines and ammonia. The hydroxyl group on the 4-hydroxyphenacyl moiety has a negligible impact on the pK a of the ammonium group ( + NH).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions

Bownik¹,

Šebej²,

Literák³

et al. 2015

J. Org. Chem.

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Irradiation of N-protected p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups as their conjugate acids. For example, the overall quantum yields of simple secondary amines release are 0.5 at acidic pH from 3.9 to 6.6 dropping to 0.1 at neutral pH 7.0 and 0.01 at pH 8.4. Speciation studies provide an acid-base profile that helps define the scope and limitations of the reaction. When the pKa of the ammonium group is lower than that of the phenolic hydroxyl group, as is the case for the α-amino-protected amino acids, the more acidic ammonium ion deprotonates as the media pH is changed from acidic toward neutral or basic, thus diminishing the leaving group ability of the amino group. This, in turn, lowers the propensity for the photo-Favorskii rearrangement reaction to occur and opens the reaction pathway to alternative competing photoreduction process.

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“…E: ethanol, W: water, Cys = L-cysteine, Tyr = L-tyrosine, Trp = L-tryptophane, Lys = L-lysine, and His = L-histidine. a Data taken from reference [50]; log⁡ K 1 : corresponds to 11 species (i.e., L − + H + ⇌ LH); log⁡ K 2 corresponds to 12 species (i.e., LH + H + ⇌LH 2 + ). The % is expressed as (volume/Volume).…”

Section: Figurementioning

confidence: 99%

Protonation Equilibria of Biologically Active Ligands in Mixed Aqueous Organic Solvents

El‐Sherif

Shoukry

El-Karim

et al. 2014

Bioinorganic Chemistry and Applications

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Solvent Effects on the Protonation Constants of Some α-Amino Acid Esters in 1,4-Dioxane–Water Mixtures

Cited by 12 publications

References 28 publications

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

Interaction of pH-sensitive non-phospholipid liposomes with cellular mimetic membranes

4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions

Protonation Equilibria of Biologically Active Ligands in Mixed Aqueous Organic Solvents

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