H-aggregation of cationic palladium-porphyrin as a function of anionic surfactant studied using phosphorescence, absorption and RLS spectra

Supramolecular Self-Assembly of Porphyrin and Metallosurfactant as a Drug Nanocontainer Design

The combined method of treating malignant neoplasms using photodynamic therapy and chemotherapy is undoubtedly a promising and highly effective treatment method. The development and establishment of photodynamic cancer therapy is closely related to the creation of sensitizers based on porphyrins. The present study is devoted to the investigation of the spectroscopic, aggregation, and solubilization properties of the supramolecular system based on 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) and lanthanum-containing surfactant (LaSurf) in an aqueous medium. The latter is a complex of lanthanum nitrate and two cationic amphiphilic molecules of 4-aza-1-hexadecylazoniabicyclo[2.2.2]octane bromide. The mixed TSPP–LaSurf complexes can spontaneously assemble into various nanostructures capable of binding the anticancer drug cisplatin. Morphological behavior, stability, and ability to drug binding of nanostructures can be tailored by varying the molar ratio and the concentration of components. The guest binding is shown to be additional factor controlling structural rearrangements and properties of the supramolecular TSPP–LaSurf complexes.

Synthesis and characterization of novel porphyrin-cinnamic acid conjugates

A series of novel porphyrin-cinnamic acid (porphyrin/CA) conjugates (4a-4c) have been synthesized by condensation of 5-(4-Hydroxyphenyl)-10,15,20-triphenyl- porphyrin (1) with different substituted cinnamic acids (CAs) through an alkyl linker due to the biological activities of CAs and the application of porphyrins in photodynamic therapy (PDT) of cancer. Their related zinc (II) complexes (5a-5c) were also prepared. These novel compounds have been fully characterized by ¹H NMR, Infrared (IR), Mass spectra (Ms) and Elemental analysis. The photophysical properties of these target molecules were studied by absorption and Fluorescence spectroscopy. In solution, the effect of pH, ionic strength in acid media and concentration on the aggregation behaviors of 4a has also been investigated by UV-Vis spectra. The broadened and red shifted Soret band indicated the formation of J-aggregates when the pH value was up to 2.0 in THF-aqueous solution. Furthermore, the higher ionic strength of 0.3 M NaCl in acid media resulted in the generation of J-aggregates in THF-aqueous solution. And the significant blue shift of Soret band also demonstrated the formation of H-aggregates of 4a at 1.1 × 10^-4 M in THF.

Room temperature phosphorescence of five PAHs in a synergistic mesoporous silica nanoparticle-deoxycholate substrate

A synergistic mesoporous silica nanoparticle-sodium deoxycholate (mPS-NaDC) substrate was developed for room temperature phosphorimetry. The synergistic substrate exhibited rapid and strong RTP-inducing ability against temperature variation. NaDC might adsorb on the inner surface of mPS pore by possible hydrogen bonding and protected the triplet state of polycyclic aromatic hydrocarbons (PAHs) with different molecular sizes. Two mPSs named LPMS1 and LPMS2 with pore size of 3.05 and 3.83nm were synthesized and optimized in inducing RTP, and the latter, LPMS2, was selected as an ideal substrate because of its stronger protection ability to the triplet and good stability. Dibromopropane and cyclohexane were also used as assistant phosphorescence-inducers. All results demonstrated the feasibility and application potential of synergistic mPS-NaDC substrate in phosphorimetry. The interaction detail of NaDC and inner surface of selected mPS still needs to be explored in future.

A room temperature phosphorescence encoding [2]rotaxane molecular shuttle

A novel bistable molecular shuttle, composed of a Pt(ii) porphyrin-containing dibenzo[24]crown-8 macrocycle threaded onto two different recognition sites (secondary dialkylammonium (NH2+) and 4,4'-bipyridinium (Bpym2+) units), and the anthracene (Anth) moiety as one terminal stopper, was synthesized by click chemistry. Its acid-base switchable shuttling could be addressed by both the room temperature phosphorescence (RTP) emission signals of the Pt(ii) porphyrin moiety and the fluorescence emission of the Anth unit, as well as their lifetime changes. When the macrocycle was switched to be located on the NH2+ site close to Anth, the Pt(ii) porphyrin moiety exhibited strong RTP emission, excited in the Anth band at 370 nm. This was due to the distance-dependent efficient singlet energy transfer between the Anth unit and the porphyrin moiety, followed by intersystem crossing from a singlet to a triplet state in Pt(ii) porphyrin, while its RTP emission dramatically decreased when located on the Bpym2+ site far from the Anth unit. When excited in the porphyrin band at 402 nm, the RTP emission lifetimes changed obviously. This is the first rotaxane-type molecular shuttle whose shuttling has been encoded by RTP signals.

Cationic Porphyrin-Anionic Surfactant Mixtures for the Promotion of Self-Organized 1:4 Ion Pairs in Water with Strong Aggregation Properties

We performed a systematic study on the spectroscopic and aggregation properties of stoichiometric mixtures (1:4) of the tetracationic meso-tetrakis(4-N-methylpyridinium)porphyrin (H2 TMPyP) and three sodium alkylsulfate surfactants (tetradecyl, hexadecyl, and octadecylsulfate) in an aqueous solution. The objective was to build a supramolecular aggregate, which would favor the internalization of tetracationic porphyrins in cells without chemical modification of the structure of the porphyrin. We show that stoichiometric H2 TMPyP/alkylsulfate (1:4) mixtures lead to the formation of large hollow spherical aggregates (60-160 nm). The TEM images show that the membrane of these aggregates are composed of smaller aggregates, which are probably rod-like micelles. These rod-like micelles have a hydrophobic core composed of the alkyl chains of the alkylsulfate surfactant, whereas the charged surface corresponds to the tetracationic porphyrins.

Using gold nanoparticles as probe for detection of salmeterol xinafoate by resonance Rayleigh light scattering

The paper explores the method of determination of salmeterol xinafoate at nanogram level with gold nanoparticles (AuNPs) probe, to measure the intensity of resonance Rayleigh light scattering (RLS) by a common spectrofluorometer. The RLS intensity of salmeterol xinafoate was greatly enhanced by AuNPs, with the maximum scattering peak at 357 nm. The salmeterol xinafoate was determined basing on the binding of salmeterol xinafoate to AuNPs by electrostatic adsorption. Under the optimum conditions, the enhanced RLS intensity was directly proportional to the concentration of salmeterol xinafoate in the range of 0.054-6.038 μg mL(-1) with a good linear relationship (r=0.9928). The limit of detection (LOD) was 9.48 ng mL(-1). The interference tests were performed carefully. With the proposed method, the synthetic samples were analyzed satisfactorily, the recovery and RSD were 102.5-103.0% and 0.67-1.0% respectively.

Investigation on the effect of water on the spectroscopic behaviors of TPPS in acidic imidazolium-based ionic liquids

The effect of water on the spectroscopic behaviors of meso-tetrakis-(4-sulfonatophenyl) porphyrin (TPPS) in acidic 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) is investigated by spectroscopic methods. In acidic ionic liquids without water, the Soret bands of the protonated form (H4TPPS2-) and J-aggregates of TPPS are centered at 449 and 469 nm, respectively, and the Q-band is centered at 679 nm. When increasing the content of water, the Soret band of H4TPPS2- is blue-shifted to 430 nm. However, the Soret and Q-bands of J-aggregates are red-shifted to 487 and 701 nm, respectively. The NMR and pyrene-scale polarity experiments reveal that the change of the bulk environment is responsible for the red-shift of J-aggregates and the blue-shift of H4TPPS2-. According to the analysis of the fluorescence spectra, the content of H4TPPS2- increases gradually with the addition of water, while the content of H2TPPS4- takes the opposite trend. Simultaneously, the content of J-aggregates decreases substantially when the addition of water is 0 ~ ca. 12 μL (or 13 μL) but it decreases slowly with further addition of water. Remarkably, the fluorescence intensity of J-aggregates is relatively strong. In addition, the fluorescence of J-aggregates can be detected when λex is set at both λex for TPPS monomers and λex for J-aggregates. While the fluorescence of TPPS monomers can be detected only when λex is set at λex for monomers. Moreover, with the addition of water, the fluorescence lifetimes of H2TPPS4- and H4TPPS2- increase from 3.202 and 0.830 ns to 9.623 and 2.964 ns, respectively.

An investigation on the interaction of DNA with hesperetin/apigenin in the presence of CTAB by resonance Rayleigh light scattering technique and its analytical application

Two new systems for measuring DNA at nanogram levels by a resonance Rayleigh light scattering (RLS) technique with a common spectrofluorometer were proposed. In the presence of cetyltrimethylammonium bromide (CTAB), the interaction of DNA with hesperetin and apigenin (two effective components of Chinese herbal medicine) could enhance RLS signals with the maximum peak at 363 and 433 nm respectively. The enhanced intensity of RLS was directly proportional to the concentration of DNA in the range of 0.022-4.4 μg mL(-1) for DNA-CTAB-hesperetin system and 0.013-4.4 μg mL(-1) for DNA-CTAB-apigenin system. The detection limit was 2.34 ng mL(-1) and 2.97 ng mL(-1) respectively. Synthetic samples were measured satisfactorily. The recovery of DNA-CTAB-hesperetin system was 97.3-101.9% and that of DNA-CTAB-apigenin system was 101.2-109.5%.

Calculation and prediction of rate and equilibrium constants for aggregation of porphyrin by molecular dynamics, Docking and QSPR methods

The aggregation of 85 porphyrin derivatives and a report on a kinetic and thermodynamic study of such aggregation behavior on varying the derivatives of porphyrin was carried out using molecular dynamics simulation and Docking. Distance diagrams of simulated compounds were obtained and decrease of curves is a clear evidence of the aggregation. Aggregation rates were studied by origin software. In order to calculate interaction energies of derivatives, compounds were docked and the equilibrium constant of porphyrin-porphyrin interaction were obtained. Quantitative Structure-Property Relationship (QSPR) studies were performed for the sets of 85 Porphyrin derivatives. Multiple Linear Regression method (MLR) and Principal Component Analysis (PCA) were used and resulted in useful models with good prediction ability. This models were able to predict the kinetic and equilibrium constant for all sets of our compounds. The correlation coefficients for prediction of rate and logarithm of equilibrium constants were 0.67 and 0.97 by MLR method respectively and 0.90 for prediction of equilibrium constant by PCA analyses. In order to have a better prediction, compounds were divided into two groups, oxygenated and non-oxygenated group and correlation coefficient for prediction of rate constants of them were obtained 0.89 and 0.94 by MLR model respectively. Results of structure-property relationship showed that, larger, more hydrophobe and more planner derivatives have higher aggregation rate.

Dimeric spectra analysis in Microsoft Excel: a comparative study

The purpose of this work is to introduce the reader to an Add-in implementation, Decom. This implementation provides the whole processing requirements for analysis of dimeric spectra. General linear and nonlinear decomposition algorithms were integrated as an Excel Add-in for easy installation and usage. In this work, the results of several samples investigations were compared to those obtained by Datan.