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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]

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]

The present paper focuses on the synthesis and characterization of new hydrogels and drug delivery systems, designed for local therapy. The hydrogels were obtained by reacting PEG-ylated chitosan derivatives with citral in different molar ratios of their functionalities. The drug delivery systems were obtained by the in situ hydrogelation of PEG-ylated chitosan derivatives with citral, in the presence of a hydrophilic anti-inflammatory drug, diclofenac sodium salt. The hydrogels and the drug delivery systems were characterized from the structural, supramolecular and morphological points of view by FTIR spectroscopy, wide angle X-ray diffraction, polarized optical microscopy and scanning electron microscopy. The in vitro release kinetics of the drug has been monitored in physiological conditions, while the in vivo release was evaluated by the somatic pain model on rats. The in vitro enzymatic degradability of the hydrogels was evaluated in the presence of lysozyme, leading to a significant mass loss of 47% in 21 days. All the findings, recommend the investigated materials as promising candidates for local drug delivery applications. Unlabelled Image [ABSTRACT FROM AUTHOR]

The objective of this paper was to investigate the new formulations based on salicyl-imine-chitosan hydrogels as potential controlled drug release systems. They were prepared by in situ hydrogelation of chitosan with salicylaldehyde in the presence of diclofenac sodium salt ( DCF ) as model drug. FTIR, X-ray Spectroscopy, POM and SEM techniques were used to confirm the structural, supramolecular and morphological particularities of the formulations. Swelling test, in vitro enzymatic biodegradation and release profile were investigated in similar conditions mimicking the in vivo environment, and the release mechanism was assessed by fitting into five mathematical models. It was established that the formulations have the capacity to release DCF in a sustained manner for 10 days rate, the drug release rate being correlated to the crosslinking density and hydrogelation speed. The biodegradation occurred in three main stages, reaching a mass loss of 48% after 21 days. In order to be used in the biomedical field, the in vivo biocompatibility of the formulations was investigated on experimental rats. After 7 days of subcutaneous implantation, no influence on the hematologic profile, liver, kidney or immune defence capacity were observed, suggesting these formulations as valuable materials for biomedical devices. • New formulations based on chitosan, salicylaldehyde and DCF were prepared by in situ hydrogelation • They presented porous morphology and fast swelling in physiological pH • The in vivo release study showed a prolonged DCF release, reaching 70% within 10 days • The formulations were enzymatic biodegraded attaining a mass loss of 48 % after 21 days • They display in vivo biocompatibility on rats [ABSTRACT FROM AUTHOR]

The purpose of the study was to develop new antimicrobial hydrogels from natural resources that may promote wound healing and prevent bacterial skin infection. The new hydrogels were synthesized by crosslinking chitosan with a vanillin isomer, 5-methoxysalicylaldehyde, by a friendly and easy method. To characterize these hydrogels, their structural and morphological properties were explored by FTIR, 1H NMR, SEM, POM, and TGA. In view of the targeted application, swelling behavior, biodegradability, antimicrobial activity and biocompatibility were investigated in vitro. Structural and morphological studies confirmed the formation of new hydrogels via the imination reaction concomitant with the supramolecular organization. The hydrogels were highly porous with the average pore diameter around 80 μm, and a swelling rate controlled by the crosslinking density and medium pH. The hydrogels showed a progressive weight loss in the presence of lysozyme up to 35%, during 21 days of testing. They proved non-cytotoxic effect on Normal Human Dermal Fibroblasts using MTS test and powerful antifungal activity against Candida Albicans , as determined by disk diffusion assay. All these properties indicate the new hydrogels as a promising option for the treatment of various skin lesions. [Display omitted] • New hydrogels based on chitosan and a vanillin isomer were synthetized via imine linkage. • The hydrogels were highly porous, thermally stable and biodegradable. • The reversible imine linkage prompted a self-healing behavior. • The hydrogels had no cytotoxic effect on normal human dermal fibroblasts. • They exhibited antifungal activity. [ABSTRACT FROM AUTHOR]

Vitamin B6 is an essential micronutrient in the mammalian diet, with role of coenzyme and synergistic effect with some antibiotics and antitumor drugs. Based on these, we hypothesized that its use for the preparation of hydrogels can yield multifunctional biomaterials suitable for in vivo applications. To this aim, chitosan was reacted with the active form of vitamin B6, pyridoxal 5-phosphate, via acid condensation, when clear hydrogels were obtained. Their investigation by structural characterization methods proved that the hydrogelation was a consequence of both covalent imine formation and physical interactions. The novel hydrogels had microporous morphology and showed shrinking effect in phosphate buffer, indicating good shape preservation and slow dissolution in in vivo environment. Their enzymatic biodegradation could be controlled by the imination degree, varying from 40 to 61% in 21 days. They demonstrated very good in vitro cytocompatibility on normal human dermal fibroblasts cells and no harmful effect on experimental mice, confirming their safely use for in vivo application. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper presents the synthesis and characterization of poly(trimethylene carbonate) grafted chitosan as a new water soluble biopolymer suitable for in vivo applications. The synthesis was performed via ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) (TMC) monomer, initiated by the functional groups of chitosan in the presence of toluene as solvent/swelling agent. By varying the molar ratio between the glucosamine units of chitosan and TMC, a series of chitosan derivatives with different content of poly(trimethylene carbonate) chains was synthetized. The structural characterization of the polymers was realized by FTIR and 1H NMR spectroscopy and their solubility was assessed in water and in organic solvents as well. The biocompatibility was investigated by MTS assay on Normal Human Dermal Fibroblasts, and the biodegradability was evaluated in lysozyme buffer solution. Further, the surface properties of the polymer films were analyzed by polarized optical microscopy, atomic force microscopy and water-to-air contact angle measurements. It was established that, by 5% substitution of chitosan with poly(trimethylene carbonate) chains having an average polymerization degree of 7, a water soluble polymer can be attained. Compared to the pristine chitosan, it has improved biocompatibility in solution and moderate wettability and higher biodegradability rate in solid state, pointing its suitability for in vivo applications. [ABSTRACT FROM AUTHOR]

The aim of the paper was to investigate the ability of an eco-friendly luminescent xerogel prepared by chitosan crosslinking with a phenothiazine luminogen to detect and remove heavy metals. Its ability to give a divergent morphological and optical response towards fifteen environmental relevant metals was investigated by naked eye and UV lamp, fluorescence spectroscopy and scanning electron microscopy. A distinct response was noted for mercury, consisting in the transformation of the xerogel into a rubber-like material accompanied by the red shifting of the color of emitted light from yellow-green to greenish-yellow domain. The particularities of the metals anchoring into the xerogel were analyzed by FTIR spectroscopy and X-ray diffraction. The morphological changes and the metal uptake were analyzed by SEM-EDAX, swelling and gravimetric methods. It was concluded that mercury has a superior affinity towards this heteroatoms rich system, leading to a secondary crosslinking. This directed a great absorption capacity of 1673 mg/g and a specific morphological response for mercury ion concentrations up to 0.001 ppm. • A luminescent organic xerogel was investigated for heavy metal detection and removal. • The xerogel showed a distinct morphological behavior towards mercury ions. • This was sensible and selective over a large series of environment relevant metals. • This was attributed to a secondary morphology due to a supplementary crosslinking. [ABSTRACT FROM AUTHOR]