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Spherical structures built from uni- and multilamellar lipid bilayers (LUV and MLV) are nowadays considered not just as nanocarriers of various kinds of therapeutics, but also as the vehicles that, when coupled with gold (Au) nanoparticles (NPs), can also serve as a tool for imaging and discriminating healthy and diseased tissues. Since the presence of Au NPs or their aggregates may affect the properties of the drug delivery vehicle, we investigated how the shape and position of Au NP aggregates adsorbed on the surface of MLV affect the arrangement and conformation of lipid molecules. By preparing MLVs constituted from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in the presence of uncoated Au NP aggregates found i) both within liposome core and on the surface of the outer lipid bilayer, or ii) adsorbed on the outer lipid bilayer surface only, we demonstrated the maintenance of lipid bilayer integrity by microscopic techniques (cryo-TEM, and AFM). The employment of SERS and FTIR-ATR techniques enabled us not only to elucidate the lipid interaction pattern and their orientation in regards to Au NP aggregates but also unequivocally confirmed the impact of Au NP aggregates on the persistence/breaking of van der Waals interactions between hydrocarbon chains of DPPC. [ABSTRACT FROM AUTHOR]

Copper(II) complexes with cysteine and histidine, amino acids that coordinate copper(II) in human body, were investigated. Cu-His and Cu-Cys complexes were detected in pH range from 5.0 to 9.0 using voltammetric techniques. [CuHis2] complex reduces by two-electron reversible process at ≈−0.40 V, while [CuCys] complex by one-electron quasireversible process at −0.6 V, revealing strong adsorption at the electrode surface. When both amino acids are present in the solution, new peak appeared at −0.5 V, which corresponded to the [CuHisCys] complex reduction. Formation and characterization of mixed ligand complex was also supported by UV-Vis spectra recorded at fixed histidine and various cysteine concentrations. Formation of [CuHisCys] complex in the solution was detected and stability constant calculated to amount to log KCuHisCys=16.9±0.3. This study was the first attempt to characterize formation of Cu(II) mixed ligand complexation process with biochemically important amino acids in electron transport and oxygenation reactions in human body. [ABSTRACT FROM AUTHOR]