Up-Conversion Luminescence of Gold Nanospheres When Excited at Nonsurface Plasmon Resonance Wavelength by a Continuous Wave Laser

We show that, when gold nanospheres are excited at the red side of the surface plasmon resonance (SPR) wavelength at 592 nm by a continuous wave (CW) laser, they give substantial up-converted luminescence in the SPR wavelength range. The luminescence intensity scales as a second-order function of the excitation power, with a quantum yield ∼1/50 of down-conversion luminescence when illuminated at a power of 30 MW/cm². The luminescence spectrum is completely different than the SPR profile, indicating a new emission mechanism possibly involving interband transitions coupled with phonons or localized vibration of neighboring gold atoms. Such luminescence is also observed to be substantial for short gold nanorods with an aspect ratio of ∼2 but weak for bulk gold. This study provides new insight to the understanding of gold nanoparticle luminescence and opens a new detection scheme for gold nanoparticle-based biological imaging

Design of a Universal Reversible Bidirectional Current Switch Based on the Fullerene–Phthalocyanine Supramolecular System

A novel bidirectional current ON–OFF switch controlled by electron injection and deprivation was proposed on the basis of the density functional theory (DFT) calculation over a fullerene–phthalocyanine supramolecular system PcCoC₆₀ for the first time. The electron density for PcCoC₆₀ was revealed to move from fullerene to phthlocyanine only in the oxidized form and from phthlocyanine to fullerene only in the reduced form, reaching the control of electron movement direction by changing the oxidation state of this supramolecular system

Design of a Universal Reversible Bidirectional Current Switch Based on the Fullerene–Phthalocyanine Supramolecular System

A novel bidirectional current ON–OFF switch controlled by electron injection and deprivation was proposed on the basis of the density functional theory (DFT) calculation over a fullerene–phthalocyanine supramolecular system PcCoC₆₀ for the first time. The electron density for PcCoC₆₀ was revealed to move from fullerene to phthlocyanine only in the oxidized form and from phthlocyanine to fullerene only in the reduced form, reaching the control of electron movement direction by changing the oxidation state of this supramolecular system

Biological Photothermal Nanodots Based on Self-Assembly of Peptide–Porphyrin Conjugates for Antitumor Therapy

Photothermal agents can harvest light energy and convert it into heat, offering a targeted and remote-controlled way to destroy carcinomatous cells and tissues. Inspired by the biological organization of polypeptides and porphyrins in living systems, here we have developed a supramolecular strategy to fabricate photothermal nanodots through peptide-modulated self-assembly of photoactive porphyrins. The self-assembling nature of porphyrins induces the formation of J-aggregates as substructures of the nanodots, and thus enables the fabrication of nanodots with totally inhibited fluorescence emission and singlet oxygen production, leading to a high light-to-heat conversion efficiency of the nanodots. The peptide moieties not only provide aqueous stability for the nanodots through hydrophilic interactions, but also provide a spatial barrier between porphyrin groups to inhibit the further growth of nanodots through the strong π-stacking interactions. Thermographic imaging reveals that the conversion of light to heat based on the nanodots is efficient in vitro and in vivo, enabling the nanodots to be applied for photothermal acoustic imaging and antitumor therapy. Antitumor therapy results show that these nanodots are highly biocompatible photothermal agents for tumor ablation, demonstrating the feasibility of using bioinspired nanostructures of self-assembling biomaterials for biomedical photoactive applications

Density Functional Theory Study on Subtriazaporphyrin Derivatives: Dipolar/Octupolar Contribution to the Second-Order Nonlinear Optical Activity

Density functional theory calculations have been carried out on the subtriazaporphyrin skeletons, an excellent prototype for investigating the dipolar/octupolar contribution to the second-order nonlinear optical (second-order NLO) activity, revealing the size effect and clarifying the nature of the limit when expanding the conjugated system is employed to improve the hyper-Rayleigh scattering response coefficient (β_HRS). The octupolar and dipolar contributions are theoretically separated, rendering it possible to control the dipolar/octupolar second-order NLO contribution ratio by changing the number and orientation of the peripheral fused benzene moieties. In addition, both the dispersion and solvent effect were also revealed to lead to the enhancement of β_HRS