Glutathione Nanosphere: Self-Assembly of Conformation-Regulated Trigonal-Glutathiones in Water

A novel trigonal conjugate of glutathiones with a 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene core was synthesized and its self-assembling behavior was investigated in water. Three glutathione units were regulated to orient on the same side of the benzene ring, through steric repulsions between ethyl groups attached on the benzene core. Concentration dependence of H-1 NMR chemical shifts in D2O revealed formation of molecular assemblies with two affinity constants (K-a = 4.75 x 10(2) and 6.76 x 10(4) M-1), which reflect stepwise assembly directed by electrostatic interactions, hydrophobic interactions, and hydrogen bonding. In scanning electron microscopy, hard spherical assemblies with the size of 310 +/- 50 nm were observed at high concentration (10mM), whereas slightly disordered spherical assemblies were obtained at lower concentrations. The spherical assemblies self-assembled from the conformation-regulated trigonal glutathiones showed regular morphology and enhanced rigidity compared to those formed from conformationally non-regulated trigonal glutathiones.