Multimeric Presentation of RGD Peptidomimetics Enhances Integrin Binding and Tumor Cell Uptake

The use of multimeric ligands is considered as a promising strategy to improve tumor targeting for diagnosis and therapy. Herein, tetrameric RGD (Arg-Gly-Asp) peptidomimetics were designed to target α_vβ₃ integrin-expressing tumor cells. These compounds were prepared by an oxime chemoselective assembly of cyclo(DKP-RGD) ligands and a cyclodecapeptide scaffold, which allows a tetrameric presentation. The resulting tetrameric RGD peptidomimetics were shown to improve α_vβ₃ integrin binding compared with the monomeric form. Interestingly, these compounds were also able to enhance tumor cell endocytosis in the same way as tetrameric RGD peptides. Altogether, the results show the potential of the tetrameric cyclo(DKP-RGD) ligands for in vivo imaging and drug delivery.     

Single crystal structure,vibrational study,and thermal behavior of a new rare earth diphosphate HYbP2O7·4H2O

A new ytterbium diphosphate: HYbP₂O₇·4H₂O was prepared via soft chemistry route from evaporation of aqueous solution. It was investigated by single crystal X-ray diffraction, vibrational spectroscopy, and thermal analysis.

The framework of the title compound consists in an assemblage of HP₂O₇ groups and [YbO₅(H₂O)₂] polyhedra, giving rise to corrugated layers stacked along the b axis at y = 1/4 and y = 3/4. Between these layers are located two uncoordinated water molecules. The cohesion of this arrangement is well ensured by a three-dimensional network of water-layer and inter-layer hydrogen bonds of different strengths. Non-coincidences are observed between the majority of the IR and Raman bands and confirm a centrosymetric structure for this compound. Thermal analysis reveals the elimination of 4.5 water molecules per formula unit in three stages between 310 K and 1100 K, which correspond to the departure of the four crystallization water molecules and the OH group. A comparative study among hydrated lanthanide monohydrogendiphosphates known in the literature is presented.     

Nitrite sensor based on multilayer film of Dawson-type tungstophosphate α-K7[H4PW18O62]·18H2O immobilized on glassy carbon

A nitrite sensor based on immobilized Dawson-type tungstophosphate α-K₇[H₄PW₁₈O₆₂]·18H₂O (PW₁₈) in multilayers of charged polyelectrolyte poly(allylamine hydrochloride) (PAH) on a glassy carbon electrode is described. A nitrite sensor manufactured with 10 layers has a sensitivity of ∼4 nA/μM nitrite, fast response time (<6 s), low detection limit (∼0.1 μM), high selectivity towards endogenous interferences such as nitrate and molecular oxygen, a linear range from 0.1 μM to at least 20 mM nitrite and was stable for at least 2 months. In addition, such nitrite sensors can operate in a pH range from 1 to 9, and the sensitivity can be increased by increasing the number of layers at the expense of increasing the response time.     

Two new 3-C-carboxylated flavones from the rhizomes of Caragana conferta

Confertins A (1) and B (2), new 3-C-carboxylated flavones, have been isolated from the ethyl acetate soluble fraction of the rhizomes of Caragana conferta. Their structures have been assigned on the basis of spectroscopic studies.     

Clay‐Na as a sorbent for the extraction of anti‐inflammatory compounds in water samples

In this work, clay‐Na particles are used as the adsorbent for the solid‐phase extraction of acidic compounds. The novel sorbent under study is based on high‐specific surface area, cation‐exchange capacity designed specifically to offer ion‐exchange properties with the goal being to selectively extract a group of acidic compounds. The effects of the extraction parameters including extraction elution solvent, sample volume and pH. In optimum conditions, the repeatability for one fiber (n = 3), expressed as % relative standard deviation, was between 0.3 and 4.3% for the acid compounds. The detection limits for the studied acidic compounds were between 0.1–0.6 μg/L. The developed method offers the advantages of being simple to use and having a low cost of equipment.     

Synthesis of 1,6-didecylnaphtho[1,2-b:5,6-b']difuran-based copolymers by direct heteroarylation polymerization

The use of direct C H arylation cross-coupling polymerization was evaluated for the synthesis of donor–acceptor conjugated co-polymers using the novel donor 1,6-didecylnaphtho[1,2-b:5,6-b']difuran and either thieno[3,4-c]pyrrole-4,6-dione (TPD) or 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) as the acceptor. Thiophene and furan moieties were used to flank the DPP group and the impact of these heterocycles on the polymers' properties was evaluated. The alkyl chains on the diketopyrrolopyrrole monomers were varied to engineer the solubility and morphology of the materials. All of the polymers have similar optoelectronic properties with narrow optical band gaps around 1.3 eV, which is ideal for solar energy harvesting. Unfortunately, these polymers also had high-lying highest occupied molecular orbital levels of −4.8 to −5.1, and as a result bulk-heterojunction photovoltaic cells fabricated using the soluble fullerene derivative PC₇₁BM as the electron-acceptor and these polymers as donor materials exhibited poor performance due to limited V_oc values. An examination of the films from these blends indicates that film-thickness and morphology were also a major hindrance to performance and a potential point of improvement for future materials.     

Photocatalytic Degradation of Oxytetracycline in Aqueous Solutions with TiO2 in Suspension and Prediction by Artificial Neural Networks

In this study, the photocatalytic degradation of oxytetracycline (OTC) in aqueous solutions has been studied under different conditions such as initial pollutant concentrations, amount of catalyst, and pH of the solution. Experimental results showed that photocatalysis was clearly the predominant process in the pollutant degradation, since OTC adsorption on the catalyst and photolysis are negligible. The optimal TiO₂ concentration for OTC degradation was found to be 1.0 g/L. The apparent rate constant decreased, and the initial degradation rate increased with increasing initial OTC concentration with the other parameters kept unchanged. Subsequently, data obtained from photocatalytic degradation were used for training the artificial neural networks (ANN). The Levenberg–Marquardt algorithm, log sigmoid function in the hidden layer, and the linear activation function in the output layer were used. The optimized ANN structure was four neurons at the input layer, eighteen neurons at the hidden layer, and one neuron at the output layer. The application of 18 hidden neurons allowed to obtain the best values for R² and the mean squared error, 0.99751 and 7.504e–04, respectively, showing the relevance of the training, and hence the network can be used for final prediction of photocatalytic degradation of OTC with suspended TiO₂.