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Betulin is a naturally originating terpenoid, which attracted the attention of researchers due to its bioactive properties, including antitumor activity. This paper reports new betulin-imine derivatives, their synthesis, structural characterization and investigation of their antioxidant and anticancer activities. To this aim, a betulin aldehyde has been firstly prepared via an oxidation reaction using a Tempo reagent, which was further reacted with a series of aliphatic amines via an acid condensation reaction. The proposed chemical structures were confirmed using 1H-NMR and FTIR spectroscopy and single crystal X-ray diffraction, and characterized by solubility tests, ultraviolet-visible (UV-Vis) and photoluminescence spectroscopy, thermogravimetric analysis and polarized light microscopy. All the compounds were easily soluble in common organic solvents, and showed good thermal stability. They showed strong birefringence under polarized light indicating their crystalline nature, which was attributed to single crystal diffraction and they belong to the Sohnke P212121 space groups. The investigation of optical properties using photoluminescence spectroscopy revealed that all the imines emitted blue light in solution and in the solid state. The DPPH radical scavenging test showed that the antioxidant activity of betulin was significantly improved by imination with the increase of the aliphatic chain length. The antitumor activity investigated in vitro using the MTS assay on human breast cancer cell line MCF-7 (adenocarcinoma) and on non-tumorigenic epithelial cell line MCF-10A showed that the betulin-imine derivatives have improved antitumor activity and selectivity compared to neat betulin, suggesting that a medium length of the alkyl chain is favorable for the antiproliferative activity. [ABSTRACT FROM AUTHOR]

The paper aims to investigate the antitumor activity of a series of phenothiazine derivatives in order to establish a structure–antitumor activity relationship. To this end, PEGylated and TEGylated phenothiazine have been functionalized with formyl units and further with sulfonamide units via dynamic imine bonds. Their antitumor activity was monitored in vitro against seven human tumors cell lines and a mouse one compared to a human normal cell line by MTS assay. In order to find the potential influence of different building blocks on antitumor activity, the antioxidant activity, the ability to inhibit farnesyltransferase and the capacity to bind amino acids relevant for tumor cell growth were investigated as well. It was established that different building blocks conferred different functionalities, inducing specific antitumor activity against the tumor cells. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the ability of a solid-state material, prepared by crosslinking chitosan with a phenothiazine-based aldehyde, to remove copper (II) ions from aqueous solutions, in a fast and selective manner. The metal uptake experiments, including the retention, sensibility, and selectivity against eight different metal ions, were realized via batch adsorption studies. The capacity of the material to retain copper (II) ions was investigated by spectrophotometric measurements, using poly(ethyleneimine) complexation agent, which allowed detection in a concentration range of 5–500 µM. The forces driving the copper sorption were monitored using various methods, such as FTIR spectroscopy, X-ray diffraction, SEM-EDAX technique, and optical polarized microscopy, and the adsorption kinetics were assessed by fitting the in vitro sorption data on different mathematical models. The phenothiazine-imine-chitosan material proved high ability to recover copper from aqueous media, reaching a maximum retention capacity of 4.394 g Cu (II)/g adsorbent when using a 0.5 M copper solution, which is an outstanding value compared to other chitosan-based materials reported in the literature to this date. It was concluded that the high ability of the studied xerogel to retain Cu (II) ions was the result of both physio- and chemo-sorption processes. This particular behavior was favored on one hand by the porous nature of the material and on the other hand by the presence of amine, hydroxyl, imine, and amide groups with the role of copper ligands. [ABSTRACT FROM AUTHOR]

Chitosan is a biopolymer originating from renewable resources, with great properties which make it an attractive candidate for plenty of applications of contemporary interest. By manufacturing chitosan into nanofibers using the electrospinning method, its potential is amplified due to the enhancement of the active surface and the low preparation cost. Many attempts were made with the aim of preparing chitosan-based nanofibers with controlled morphology targeting their use for tissue engineering, wound healing, food packaging, drug delivery, air and water purification filters. This was a challenging task, which resulted in a high amount of data, sometimes with apparent contradictory results. In this light, the goal of the paper is to present the main routes reported in the literature for chitosan electrospinning, stressing the advantages and disadvantages of each of them. Special emphasis is placed on the influence of various electrospinning parameters on the morphological characteristics of the fibers and their suitability for distinct applications. [ABSTRACT FROM AUTHOR]

A mixture of polymeric complexes based on the reaction between Re(CO)5Cl and the porous polymeric network coming from the coupling of melamine and benzene-1,3,5-tricarboxaldehyde was obtained and characterized by FTIR, NMR, SEM, XPS, ICP, XRD, and cyclic voltammetry (CV). The formed rhenium-based porous hybrid material reveals a noticeable capability of CO2 absorption. The gas absorption amount measured at 295 K was close to 44 cm3/g at 1 atm. An interesting catalytic activity for CO2 reduction reaction (CO2RR) is observed, resulting in a turn over-number (TON) close to 6.3 under 80 min of test at −1.8 V vs. Ag/AgCl in a TBAPF6 0.1 M ACN solution. A possible use as filler in membranes or columns can be envisaged. [ABSTRACT FROM AUTHOR]

Nitro compounds are widely used in modern industries. Among them, 2, 4-dinitrophenylhydrazine (DNH) is extremely harmful. It is of great significance to develop methods for the detection of DNH. In this work, chitosan was used as the substrate material, and fluoroborondipyrrole (BODIPY) was used as the fluorophore. Chitosan was endowed with the fluorescence sensing ability by the introduction of BODIPY units. First, BODIPY derivatives (NO-3 and BO-1) with an alkynyl group (C≡C) were synthesized. Second, small molecules NO-4 and BO-2 with an aldehyde group (–CHO) were obtained. Finally, the –NH2 groups on chitosan underwent a click reaction (–NH2/C≡C) and a Schiff base formation reaction occurred (–NH2/–CHO) to form three polymer probes C1, C2 and C3. C＝C formed in the click reaction can interact with DNH and can be used as recognizing sites for DNH. These chitosan probes have good thermal stability and could selectively recognize DNH, showing notable fluorescence quenching effects, which are visible to the naked eye. DNH is a typical electron-deficient compound, and the polymer fluorescent probe contains electron-rich groups, which makes it easier for the two species to combine and cause fluorescence changes. C1 is flexibly cross-linked, C3 is rigidly cross-linked, and C2 has a non-crosslinked structure, and they show different rheological properties. This work expands the application of chitosan. [ABSTRACT FROM AUTHOR]

This paper reports new solid materials based on TEGylated phenothiazine and chitosan, with a high capacity to recover mercury ions from aqueous solutions. They were prepared by hydrogelation of chitosan with a formyl derivative of TEGylated phenothiazine, followed by lyophilization. Their structural and supramolecular characterization was carried out by 1H-NMR and FTIR spectroscopy, as well as X-ray diffraction and polarized light microscopy. Their morphology was investigated by scanning electron microscopy and their photophysical behaviour was examined by UV/Vis and emission spectroscopy. Swelling evaluation in different aqueous media indicated the key role played by the supramolecular organization for their hydrolytic stability. Mercury recovery experiments and the analysis of the resulting materials by X-ray diffraction and FTIR spectroscopy showed a high ability of the studied materials to bind mercury ions by coordination with the sulfur atom of phenothiazine, imine linkage, and amine units of chitosan. [ABSTRACT FROM AUTHOR]

Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. It became popular immediately after its discovery in 1952, due to its therapeutic effect against pathogens resistant to other drugs. Despite this major advantage, ERY exhibits several drawbacks, raising serious clinical challenges. Among them, the very low solubility in water and instability under acidic conditions cause a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. Despite the interest in ERY-(nano)formulations, a review on them is lacking. Therefore, this work was aimed at reviewing all efforts made to encapsulate ERY in formulations of various chemical compositions, sizes and morphologies. In addition, their preparation/synthesis, physico-chemical properties and performances were carefully analysed. Limitations of these studies, particularly the quantification of ERY, are discussed as well. [ABSTRACT FROM AUTHOR]

The paper aims at the preparation of chitosan self-healing hydrogels, designed as carriers for local drug delivery by parenteral administration. To this aim, 30 hydrogels were prepared using chitosan and pyridoxal 5-phosphate (P5P), the active form of vitamin B6 as precursors, by varying the ratio of glucosamine units and aldehyde on the one hand and the water content on the other hand. The driving forces of hydrogelation were investigated by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, and polarized light microscopy (POM) measurements. NMR technique was also used to investigate the stability of hydrogels over time, and their morphological particularities were assessed by scanning electron microscopy (SEM). Degradability of the hydrogels was studied in media of four different pH, and preliminary self-healing ability was visually established by injection through a syringe needle. In-depth rheological investigation was conducted in order to monitor the storage and loss moduli, linear viscoelastic regime, and structural recovery capacity. It was concluded that chitosan crosslinking with pyridoxal 5-phosphate is a suitable route to reach self-healing hydrogels with a good balance of mechanical properties/structural recovery, good stability over time, and degradability controlled by pH. [ABSTRACT FROM AUTHOR]

The detection of heavy metals, such as Hg2+ and Fe3+, is of great significance. In this work, fluorescent small-molecule BODIPY (BY-3) bearing C C group was synthesized firstly. And then, the chitosan-based polymer sensor CY-1 was synthesized through the spontaneous NH 2 /C≡C click reaction. The synthesized CY-1 can effectively bind and recognize Hg2+/Hg+ by the –C=N groups formed in the click reaction. Moreover, the macromolecular sensors CS-1 and CS-2 were synthesized by incorporating another recognition sites to CY-1. These synthesized macromolecular sensors can not only recognize Hg2+/Hg+, but also effectively recognize Fe3+/Fe2+. All of them exhibited significant quenching effect, visible to the naked eye under UV irradiation. The detection limit of CY-1 for Hg2+ was 1.51 × 10−6 mol/L, and the detection limit of CS-2 for Fe3+ was 2.30 × 10−6 mol/L. The BODIPY-chitosan sensors synthesized in this work have the functions of removing heavy metal ions besides the identifying ability. The maximum adsorption capacity of 1 g chitosan to Hg2+ was 108 mg as the best one. This article provides a new method to prepare macromolecular sensors for the detection and removal of heavy metal ions. As a useful natural polymer, chitosan's application scope was enlarged. Small-molecule fluorescent monomer BODIPY(BY-3) with C C group was first synthesized. And then, the chitosan-based polymeric sensor CY-1 was synthesized through the NH 2 /C C click reaction. The synthesized macromolecular sensor could not only recognize Hg2+/Hg+, but also effectively recognize Fe3+/Fe2+. [Display omitted] • Solubility of chitosan derived polymer in H 2 O-HAc remains despite the attachment of a large organic group. • By Click reaction, BODIPY fluophores were linked to chitosan with C N, it can recognize Hg2+ and Hg+ well. • By introducing the recognition site S, it can recognize not only Hg2+/Hg+, but also Fe3+/Fe2+. • The functionalized can adsorb and remove heavy metal ions with high efficiency. [ABSTRACT FROM AUTHOR]

Multi-component polymers (MCPs) incorporate multiple components into the main chain or pendant group and have special functions. In this work, the small-molecule fluorescent boron-dipyrromethene (BODIPY), with ester groups and/or alkoxyl long chains, was synthesized first. Then, this small-molecule BODIPY and the components containing C＝C bonds (HD and PD) were reacted via the Heck coupling reaction to obtain macromolecular probes that perform different functions. With the help of ester groups and alkoxyl "tail", polymers MCP1 and MCP2 were soluble in a variety of water-miscible organic solvents. Moreover, MCP3 and MCP4 were completely soluble in water. These macromolecular probes showed sensitive and selective recognition toward Hg2+/Hg+ because of the introduced components (HD and PD) containing C＝C bonds. After binding to Hg2+/Hg+, MCP1 and MCP2 demonstrated fluorescence quenching and color changes, which allowed the dual-channel specific detection of Hg2+/Hg+. Compared with the probes containing HD, the probes containing PD showed higher sensitivity, and the good recognition ability caused the detection limit to be as low as 0.32 μM, which may be due to the "molecular wire" mechanism. The small-molecule components with different functional groups were polymerized into fluorescent polymer materials. This methodology endows the polymer probe with good solubility and high sensitivity, and the as-prepared polymers could sense metal ions in aqueous environments. [ABSTRACT FROM AUTHOR]

Chitosan has been widely used due to its biodegradable, cost-effective and environmentally friendly properties. Modification of chitosan attracts much attention as promising methods to detect and remove organic and inorganic pollutants. In this work, chitosan-based macromolecular probes were designed and synthesized. The probes can detect Fe3+ in the presence of other metal ions. The detection mechanism is investigated as well. The probe's fluorescence quenching upon the addition of Fe3+ ion could be ascribed to the complexation between the electron-deficient ion Fe3+ and "C=N" (electron-rich group) of fluorescent chitosan probes. What's more, the obtained fluorescent macromolecular probes can be used for the removal of Fe3+ in solution. The probes could adsorb the Fe3+ in solution and the removal efficiency can reach as high as 62.0% while the removal efficiency of original chitosan is only 16.0%. The probes have good selective detection for Fe3+ and the detection limit reaches 1.2 μM. [Display omitted] • BIDIPY was introduced to chitosan to obtain fluorescent macromolecular probes. • The as-prepared fluorescent macromolecular probes exhibit good sensing ability to Fe3+. • Due to the abundant S, N, and O atoms in the fluorophores, the fluorescent chitosan exhibits good removal of Fe3+. [ABSTRACT FROM AUTHOR]

Detection of heavy metals with high sensitivity and selectivity is of vital importance. In this study, we report the synthesis of small molecular chemosensors and the fabrication of corresponding macromolecular fluorescent chemosensors. Boron dipyrrole methane (BODIPY)-derived chemosensors, BE and BB, were designed and synthesized first. Then, they were incorporated into polymeric derivatives to prepare macromolecular fluorescent chemosensors. The small molecular sensors were highly sensitive and selective to Hg2+. Other ions and albumin did not exhibit clear interference to the sensing of Hg2+ ions. Once the macromolecular chemosensors were formed, the recognition ability was preserved; moreover, the sensitivity was even enhanced by the “molecular wire” mechanism. The minimum detection limits of four macromolecular chemosensors, PBEP, PBEB, PBBP and PBBB, for Hg2+ reached 2.05 μM, 0.23 μM, 4.23 μM, and 0.15 μM, respectively. Under natural light, the addition of Hg2+ led to significant color changes; also, they can be used as Hg2+-sensitive “naked eye” indicators in the natural environment. [ABSTRACT FROM AUTHOR]