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Hydrodynamic properties of cyclodextrin molecules in dilute solutions.

Pavlov GM, Korneeva EV, Smolina NA, Schubert US - Eur. Biophys. J. (2009)

Bottom Line: Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents.For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown.Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. g.m.pavlov@tue.nl

ABSTRACT
Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents. For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown. Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.

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Velocity sedimentation of CDs: experimental data and evaluations obtained with the Sedfit program. a α-CD with c = 4.2 × 10−3 g/cm3 in DMF, b the same solute with c = 4.8 × 10−3 g/cm3 in DMSO. Panels at the top show the superposition of some interference profiles on the whole range of sedimentation time (12 h), those at the middle the corresponding residual plots. The panels at the bottom represent the distribution of sedimentation coefficients, c(s), obtained with a regularization procedure with a confidence level of 0.70
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Fig1: Velocity sedimentation of CDs: experimental data and evaluations obtained with the Sedfit program. a α-CD with c = 4.2 × 10−3 g/cm3 in DMF, b the same solute with c = 4.8 × 10−3 g/cm3 in DMSO. Panels at the top show the superposition of some interference profiles on the whole range of sedimentation time (12 h), those at the middle the corresponding residual plots. The panels at the bottom represent the distribution of sedimentation coefficients, c(s), obtained with a regularization procedure with a confidence level of 0.70

Mentions: The velocity sedimentation and isothermal translational diffusion studies were made separately in three different solvents: water, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The solubility of the CDs studied in these solvents increases in the following order: H2O < DMF < DMSO. The velocity sedimentation experiments were run overnight (12–14 h), at a solute concentration c ≅ 4 mg/mL. Figure 1 represents the sedimentation interference profiles of α-cyclodextrin in DMF and in DMSO as well as the calculated distribution of the sedimentation coefficients, c(s), as obtained by the use of the Sedfit program. Figure 2 shows the comparison of the normalized differential distributions for γ-CD, obtained in the different solvents. The density increment (Δρ/Δc), which is also required for the quantitative interpretation of the sedimentation data, allows the determination of the partial specific volume The value remained the same for different CDs in the same solvent and was found to be 0.667, 0.632, and 0.649 cm3/g in H2O, DMF, and DMSO, respectively. The refractive index increment (Δn/Δc) also remained virtually the same for different CDs in the same solvent: 0.148, 0.104, and 0.07 cm3/g in H2O, DMF, and DMSO, respectively. The translational diffusion was studied at an average solute concentration c of ≅1–2 mg/mL (Fig. 3).Fig. 1


Hydrodynamic properties of cyclodextrin molecules in dilute solutions.

Pavlov GM, Korneeva EV, Smolina NA, Schubert US - Eur. Biophys. J. (2009)

Velocity sedimentation of CDs: experimental data and evaluations obtained with the Sedfit program. a α-CD with c = 4.2 × 10−3 g/cm3 in DMF, b the same solute with c = 4.8 × 10−3 g/cm3 in DMSO. Panels at the top show the superposition of some interference profiles on the whole range of sedimentation time (12 h), those at the middle the corresponding residual plots. The panels at the bottom represent the distribution of sedimentation coefficients, c(s), obtained with a regularization procedure with a confidence level of 0.70
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2812710&req=5

Fig1: Velocity sedimentation of CDs: experimental data and evaluations obtained with the Sedfit program. a α-CD with c = 4.2 × 10−3 g/cm3 in DMF, b the same solute with c = 4.8 × 10−3 g/cm3 in DMSO. Panels at the top show the superposition of some interference profiles on the whole range of sedimentation time (12 h), those at the middle the corresponding residual plots. The panels at the bottom represent the distribution of sedimentation coefficients, c(s), obtained with a regularization procedure with a confidence level of 0.70
Mentions: The velocity sedimentation and isothermal translational diffusion studies were made separately in three different solvents: water, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The solubility of the CDs studied in these solvents increases in the following order: H2O < DMF < DMSO. The velocity sedimentation experiments were run overnight (12–14 h), at a solute concentration c ≅ 4 mg/mL. Figure 1 represents the sedimentation interference profiles of α-cyclodextrin in DMF and in DMSO as well as the calculated distribution of the sedimentation coefficients, c(s), as obtained by the use of the Sedfit program. Figure 2 shows the comparison of the normalized differential distributions for γ-CD, obtained in the different solvents. The density increment (Δρ/Δc), which is also required for the quantitative interpretation of the sedimentation data, allows the determination of the partial specific volume The value remained the same for different CDs in the same solvent and was found to be 0.667, 0.632, and 0.649 cm3/g in H2O, DMF, and DMSO, respectively. The refractive index increment (Δn/Δc) also remained virtually the same for different CDs in the same solvent: 0.148, 0.104, and 0.07 cm3/g in H2O, DMF, and DMSO, respectively. The translational diffusion was studied at an average solute concentration c of ≅1–2 mg/mL (Fig. 3).Fig. 1

Bottom Line: Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents.For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown.Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands. g.m.pavlov@tue.nl

ABSTRACT
Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents. For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown. Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.

Show MeSH
Related in: MedlinePlus