title: Superstructure based on β-CD self-assembly induced by a small guest molecule.
abstract: The size, shape and surface chemistry of nanoparticles play an important role in cellular interaction. Thus, the main objective of the present study was the determination of the β-cyclodextrin (β-CD) self-assembly thermodynamic parameters and its structure, aiming to use these assemblies as a possible controlled drug release system. Light scattering measurements led us to obtain the β-CD's critical aggregation concentration (cac) values, and consequently the thermodynamic parameters of the β-CD spontaneous self-assembly in aqueous solution: Δ(agg)G(o) = -16.31 kJ mol(-1), Δ(agg)H(o) = -26.48 kJ mol(-1) and TΔ(agg)S(o) = -10.53 kJ mol(-1) at 298.15 K. Size distribution of the self-assembled nanoparticles below and above cac was 1.5 nm and 60-120 nm, respectively. The number of β-CD molecules per cluster and the second virial coefficient were identified through Debye's plot and molecular dynamic simulations proposed the three-fold assembly for this system below cac. Ampicillin (AMP) was used as a drug model in order to investigate the key role of the guest molecule in the self-assembly process and the β-CD:AMP supramolecular system was studied in solution, aiming to determine the structure of the supramolecular aggregate. Results obtained in solution indicated that the β-CD's cac was not affected by adding AMP. Moreover, different complex stoichiometries were identified by nuclear magnetic resonance and isothermal titration calorimetry experiments.
authors.affiliation: Laboratório de Encapsulamento Molecular e Biomateriais (LEMB), Departamento de Química, Instituto de Ciências Exatas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, 31270-901, MG, Brazil.
authors.forename: Frederico B
authors.initials: FB
authors.lastname: De Sousa
authors.forename: Ana C
authors.initials: AC
authors.lastname: Lima
authors.forename: Angelo M L
authors.initials: AM
authors.lastname: Denadai
authors.forename: Cleber P A
authors.initials: CP
authors.lastname: Anconi
authors.forename: Wagner B
authors.initials: WB
authors.lastname: De Almeida
authors.forename: Willian T G
authors.initials: WT
authors.lastname: Novato
authors.forename: Hélio F
authors.initials: HF
authors.lastname: Dos Santos
authors.forename: Chester L
authors.initials: CL
authors.lastname: Drum
authors.forename: Robert
authors.initials: R
authors.lastname: Langer
authors.forename: Rubén D
authors.initials: RD
authors.lastname: Sinisterra
mesh_terms: D000667:Ampicillin / Q000737:chemistry*; D002151:Calorimetry; D004337:Drug Carriers / Q000737:chemistry; D008027:Light; D056004:Molecular Dynamics Simulation; D053758:Nanoparticles / Q000737:chemistry; D012542:Scattering, Radiation; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D047392:beta-Cyclodextrins; D014867:Water; D000667:Ampicillin; C031215:betadex