Recently, nanocarriers that transport bioactive substances to a target site in the body have attracted considerable attention and undergone rapid progression in terms of the state of the art. However, few nanocarriers can enter the brain via a systemic route through the blood-brain barrier (BBB) to efficiently reach neurons. Here we prepare a self-assembled supramolecular nanocarrier with a surface featuring properly configured glucose. The BBB crossing and brain accumulation of this nanocarrier are boosted by the rapid glycaemic increase after fasting and by the putative phenomenon of the highly expressed glucose transporter-1 (GLUT1) in brain capillary endothelial cells migrating from the luminal to the abluminal plasma membrane. The precisely controlled glucose density on the surface of the nanocarrier enables the regulation of its distribution within the brain, and thus is successfully optimized to increase the number of nanocarriers accumulating in neurons.

Hydration of ion pairs is an essential process in various physicochemical phenomena occurring in solutions. Isolated clusters of an ion pair solvated with finite number of waters have been considered as a model system for the critical evaluation of microscopic interactions involved in the process, and theoretical studies have contributed exclusively to the subject up to now. Here we report the first experimental characterization of structure and internal dynamics of hydrated ion pairs, NaCl-(H2O)n (n = 1-3). The measurements of their rotational spectra have proven that the clusters have cyclic forms, in which Na+ and Cl- ions are strongly interacted with the O and H atoms of the solvent molecules, respectively. The Na-Cl distance shows a pronounced increase with the successive addition of water molecules. The separation for n = 3 approaches the value predicted for the contact ion-pair state in aqueous solution by recent molecular dynamics simulations.

Pure rotational spectra of the sodium chloride-water complexes, NaCl-(H(2)O)(n) (n = 1, 2, and 3), in the vibronic ground state have been observed by a Fourier- transform microwave spectrometer coupled with a laser ablation source. The (37)Cl-isotopic species and a few deuterated species have also been observed. From the analyses of the spectra, the rotational constants, the centrifugal distortion constants, and the nuclear quadrupole coupling constants of the Na and Cl nuclei were determined precisely for all the species. The molecular structures of NaCl-(H(2)O)(n) were determined using the rotational constants and the molecular symmetry. The charge distributions around Na and Cl nuclei in NaCl are dramatically changed by the complex formation with H(2)O. Prominent dependences of the bond lengths r(Na-Cl) on the number of H(2)O were also observed. By a comparison with results of theoretical studies, it is shown that the structure of NaCl-(H(2)O)(3) is approaching to that of the contact ion-pair, which is considered to be an intermediate species in the incipient solvation process.

The first spectroscopic identification of a van der Waals complex containing salt, Ar-NaCl, has been reported. A cm-region rotational spectrum of the complex has been observed for the 35 Cl and