Spectral properties of tetraanionic porphyrin in formamide colloids of layered double hydroxides

Abstract

Formamide colloidal suspensions of layered double hydroxides (LDHs) with anionic dye, meso-tetrakis(4-sulfonatophenyl)porphine (TPPS) were prepared. Optical properties of these suspensions were investigated by means of absorption and fluorescence spectroscopies in the visible region. For more detailed characterization, second derivative curves of the spectra were calculated. The adsorption of the dye on LDH nanosheets led to partial molecular aggregation, reflected in significant changes of the dye optical properties. The Soret band in the absorption spectra was split into two peaks and decreased in intensity. Changes were observed also for the Q-bands. The molecular aggregation significantly quenched the emission of the dye. The low intensity emission from dye H-aggregates was identified at slightly longer wavelengths. The molecular aggregation increased with the dye/LDH ratio. At low dye loadings, the optical properties were very similar to the dye solution. The yields of the dye molecular aggregation increased with LDH surface charge.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

Layered Hydroxide–Porphyrin Hybrid Materials: Synthesis, Structure, and Properties

“…The Soret band of PdTPPS in the Mg 2 Al‐LDH‐DS/PdTPPS films is also slightly broadened, and the Q(1,0) band is redshifted by 3 nm relative to the absorption spectrum of monomeric PdTPPS in aqueous solution. In comparison, the aggregates of TPPS in solution,25,26 in the mesopores of MCM‐41,27 or on the surface of LDH nanosheets28 are characterized by profound shifts and broadening of the absorption bands; these features were not observed with the films. The results for the films are similar to those reported for Mg 2 Al‐LDH‐PdTPPC,29 Zn R Al‐LDH‐ZnTPPS and Mg R Al‐LDH‐TPPS ( R = 2 or 4),13,29,30 and Zn R Al‐LDH‐PdTPPC ( R = 2 or 4)31 hybrids (Figure 5).…”

A targeted agent with intercalation structure for cancer near-infrared imaging and photothermal therapy

“…[39][40][41] It has been reported that the dispersity and stability of organic molecules can be highly improved aer their intercalation into LDH interlamellar gallery. [42][43][44] Moreover, LDHs have also been investigated as drug nanocarriers due to their low toxicity, enhanced cellular uptake and good biodegradation. [45][46][47] This motivates us to co-intercalate photothermal molecule (indocyanine green, ICG) and targeting agent (folic acid, FA) into the interlayer of LDH, so as to obtain a new targeted photothermal agent used in PTT, which would exhibit the following advantages: (i) the host-guest interactions would improve the stability of ICG, extend half-life period and thus increase the efficiency of photo-thermal transformation; (ii) the organic-inorganic composite structure promotes the hydrophilicity and biocompatibility of ICG, leading to an enhancement in drug permeability/retention.…”