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Abstract Because organic molecules and materials are generally insensitive or weakly sensitive to magnetic fields, a certain means to enhance their magnetic responsiveness needs to be exploited. Here we show a strategy to amplify the magnetic responsiveness of self-assembled peptide nanostructures by synergistically combining the concepts of perfect α-helix and rod-coil supramolecular building blocks. Firstly, we develop a monomeric, nonpolar, and perfect α-helix (MNP-helix). Then, we employ the MNP-helix as the rod block of rod-coil amphiphiles (rod-coils) because rod-coils are well-suited for fabricating responsive assemblies. We show that the self-assembly processes of the designed rod-coils and disassembly of rod-coil/DNA complexes can be controlled in a magnetically responsive manner using the relatively weak magnetic field provided by the ordinary neodymium magnet [0.07 ~ 0.25 Tesla (T)]. These results demonstrate that magnetically responsive organic assemblies usable under practical conditions can be realized by using rod-coil supramolecular building blocks containing constructively organized diamagnetic moieties.

Vesicles such as liposomes, polymersomes, and exosomes have been widely used as drug delivery carriers; however, peptide vesicles (peptidesomes) despite their potential utility are far less well developed. Peptidesomes are distinctive because peptides play dual roles as a self-assembly building block and a bioactive functional unit. In order for peptidesomes to become successful nanodrugs, the issues related to differences in nanostructural properties between in vitro and in vivo conditions should be addressed. Here, we delineate a multivariate approach to feedback control the structures of peptide building blocks, nanoparticle size, drug loading process, nanoparticle aggregation, cytotoxicity, cell targeting capability, endosome disruption function, protease resistance, and in vivo performance, which eventually enabled the successful development of a highly efficacious peptidesome for in vivo cancer therapy. This study lays the groundwork for the successful in vivo translation of peptide nanodrugs.

One-photon mass-analyzed threshold ionization (MATI) spectrum of CH2BrI was obtained using coherent vacuum-ultraviolet radiation generated by four-wave difference-frequency mixing in Kr. Unlike CH2ClI investigated previously, a very extensive bending (Br–C–I) progression was observed. Vibrational frequencies of CH2BrI+ were measured from the spectra and the vibrational assignments were made by utilizing frequencies calculated by the density-functional-theory (DFT) method using relativistic effective core potentials with and without the spin-orbit terms. A noticeable spin-orbit effect on the vibrational frequencies was observed from the DFT calculations, even though its influence was not so dramatic as in CH2ClI+. A simple explanation based on the bonding characteristics of the molecular orbitals involved in the ionization is presented to account for the above differences between the MATI spectra of CH2BrI and CH2ClI. The 0-0 band of the CH2BrI spectrum could be identified through the use of combined data from calculations and experiments. The adiabatic ionization energy determined from the position of this band was 9.5944±0.0006 eV, which was significantly smaller than the vertical ionization energy reported previously. [ABSTRACT FROM AUTHOR]

Detailed analysis of the one-photon mass-analyzed threshold ionization (MATI) spectrum of CH2ClI is presented. This includes the determination of the ionization energy of CH2ClI, complete vibrational assignments, and quantum-chemical calculations at the spin-orbit density-functional-theory (SODFT) level with various basis sets. Relativistic effective core potentials with effective spin-orbit operators can be used in SODFT calculations to treat the spin-orbit term on an equal footing with other relativistic effects and electron correlations. The comparison of calculated and experimental vibrational frequencies indicate that the spin-orbit effects are essential for the reasonable description of the CH2ClI+ cation. Geometrical parameters and thus the molecular shape of the cation are greatly influenced by the spin-orbit effects even for the ground state. Calculated geometrical parameters deviate substantially for different basis sets or effective core potentials. In an effort to derive the exact geometrical parameters for this cation, SODFT geometries were further improved utilizing Franck–Condon fit of the MATI spectral pattern. This empirical fitting produced the well-converged set of geometrical parameters that are quite insensitive to the choice of SODFT calculations. The C-I bond length and the Cl-C-I bond angle show large deviations among different SODFT calculations, but the empirical spectral fitting yields 2.191±0.003 Å for the C-I bond length and 107.09±0.09° for the Cl-C-I angle. Those fitted geometrical parameters along with the experimental vibrational frequencies could serve as a useful reference in calibrating relativistic quantum-chemical methods for radicals. [ABSTRACT FROM AUTHOR]