Search

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]

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]

The industrial production of chitosan, initiated over 50 years ago, has transformed its application across diverse industries, agriculture, and medicine. To enhance its properties, numerous chitosan derivatives have been synthesized. The quaternization of chitosan has proven beneficial, as it not only enhances its properties but also imparts water solubility, expanding its potential for a wider range of applications. Specifically, the utilization of quaternized chitosan-based nanofibers has leveraged the synergistic benefits of quaternized chitosan (including hydrophilicity, bioadhesiveness, antimicrobial, antioxidant, hemostatic, and antiviral activities, as well as ionic conductivity) in combination with the distinctive characteristics of nanofibers (such as a high aspect ratio and 3D architecture). This combination has permitted numerous possibilities, spanning from wound dressings, air and water filters, drug delivery scaffolds, antimicrobial textiles, to energy storage systems and alkaline fuel cells. In this comprehensive review, we examine the preparation methods, properties, and applications of various composite fibers containing quaternized chitosan. The advantages and disadvantages of each method and composition are meticulously summarized, while relevant diagrams and figures illustrate the key findings. [Display omitted] [ABSTRACT FROM AUTHOR]

The industrial production of chitosan, initiated over 50 years ago, has transformed its application across diverse industries, agriculture, and medicine. To enhance its properties, numerous chitosan derivatives have been synthesized. The quaternization of chitosan has proven beneficial, as it not only enhances its properties but also imparts water solubility, expanding its potential for a wider range of applications. Specifically, the utilization of quaternized chitosan-based nanofibers has leveraged the synergistic benefits of quaternized chitosan (including hydrophilicity, bioadhesiveness, antimicrobial, antioxidant, hemostatic, and antiviral activities, as well as ionic conductivity) in combination with the distinctive characteristics of nanofibers (such as a high aspect ratio and 3D architecture). This combination has permitted numerous possibilities, spanning from wound dressings, air and water filters, drug delivery scaffolds, antimicrobial textiles, to energy storage systems and alkaline fuel cells. In this comprehensive review, we examine the preparation methods, properties, and applications of various composite fibers containing quaternized chitosan. The advantages and disadvantages of each method and composition are meticulously summarized, while relevant diagrams and figures illustrate the key findings. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, fluorescent β- cyclodextrin (β-CD) based probes containing naphthalimide group were synthesized to realize the specific recognition of Hg2+/Hg+ in aqueous system. Firstly, three small fluorescent molecules (N1, N2 and N3) with -NH 2 groups were synthesized from 4-bromo-1, 8-naphthalene anhydride. Secondly, CH CCH 2 - group was introduced into β-CD by Williamson ether formation reaction. Finally, the target probes (β-CD-PI, β-CD-PY and β-CD-TP) were obtained by Amino-Yne click reaction. These probes can efficiently recognize Hg2+/Hg+. β-CD-PI emits bright yellow fluorescence after binding with Hg2+/Hg+, which is a turn-on fluorescent probe. When the Hg2+/Hg+ concentration exceeds 26 μM, the fluorescence intensity amplifies sharply (20 folds). The hydrophobic parts of the probes aggregated together to form a micelle-like structure due to complexation with Hg2+/Hg+, resulting in special micelle-sensitizing properties. Meanwhile, the HOMO-LUMO energy levels of the probes were calculated by cyclic voltammetry (CV). The probe is expected to be used for the detection of Hg2+/Hg+ in aqueous solutions without any organic solvents. [Display omitted] • Turn on fluorescent probes were prepared by a simple method. • Micellar sensitization effect leads to the amplifying fluorescence. • Specific identification of Hg2+/Hg+ ions. • Water solubility of the sensors was endowed by link of β-CD to the molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescence cellulose-based probes are synthesized. • The probes were sensitive and selective to explosives TNP and DNH. • Testing paper for TNP/DNH were obtained. 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenylhydrazine (DNH) are harmful to the environment and human beings. Trace detection of TNP and DNH is worth of developing facile methods. In this work, cellulose powder and filter paper based fluorescence sensor are synthesized. Firstly, NH 2 CH 2 CH 2 – was introduced into cellulose through etherification reaction, and at the same time, a small molecule BODIPY with –CHO was synthesized. Then BODIPY was incorporated into cellulose by Schiff base reaction to obtain fluorescent macromolecular probes. These fluorescent cellulose sensors can efficiently identify TNP and DNH, with the lowest detection limits of 2.8 × 10−7 M and 1.6 × 10−7 M, respectively. Fluorescent filter paper is obtained via the same route. They also exhibit TNP and DNH identification ability. The method developed in filter paper not only expands the application range of cellulose, but also can efficiently identify the pollutants TNP and DNH, which is of great significance in theory and practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent water-soluble polymer sensors were obtained by RAFT method. • Selective and sensitive recognition of Fe3+ and Fe2+. • Fluorophores could be incorporated as RAFT reagent and/or functional monomer. Fe3+ and Fe2+ are common metal ions in natural water environments and creatures. The development of water-soluble fluorescent sensors for detecting Fe2+/Fe3+ ions was of great significance. In this work, two kinds of boron fluoride dipyrrole (BODIPY) fluorescent small-molecules were synthesized firstly. One of the small molecules contains a thioester bond that can be used as a chain transfer agent to participate in the polymerization process, and the other contains an unsaturated C = C double bond at the meso position. Through the reversible addition-fragmentation chain transfer polymerization (RAFT) polymerization method, methacrylic acid (MAA) and methacrylamide (MAM) were used as the main monomers, and small molecular fluorescent monomers were introduced to the end of the main chain. In this way, fluorescent macromolecules were obtained. The polymers were water soluble owing to the presence of long enough hydrophilic carboxyl and amide chains. These fluorescent probes exhibit high sensitivity to Fe2+/Fe3+, good selectivity, and anti-interference of other ions. The detection limit for Fe2+ was as low as 2.3 × 10−7 M, and the detection limit for Fe3+ can reach up to 4.5 × 10−7 M. The results show that these probes can be used as good sensors to identify Fe2+ and Fe3+. Moreover, the fluorophores could be incorporated into polymer chains as the RAFT reagents and/or functional monomers. [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]

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]

[Display omitted] Over time, functionalized polysulfones have been obtained through various synthetic routes, aiming at the preparation of high-performance materials with targeted functions for specific applications. The successful use of polysulfones and chemically functionalized polysulfones in the fabrication of membranes with applicability in clinical dialyzers, separation of water/organic solvent mixtures, wastewater treatment, gas separation, fuel cells or as a support for composite membranes encourages the study of chemical modification methods of these polymers that lead to the improvement of the properties and the broadening of the applications field. This review summarizes the research progress on the development, investigation, and application of functionalized polysulfones and analyzes why some of their properties, especially surface and morphological ones, should be considered for their extensive use in industrial and environmental scope, membranes for electro-electrodialysis, separation of enantiomer mixtures, ultrafiltration and direct osmosis processes, removal of metals, anion or proton exchange membranes for fuel cells, but also in the biomedical field as hemodialysis membranes, immune response modulators, materials with antimicrobial activity. In addition, the present review highlights the challenges and recent advances achieved through various synthetic approaches that overcome the existing problems and improve the performance of these polymers in medical and industrial fields. [ABSTRACT FROM AUTHOR]

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]

In the period 2020-2022 as a result of epidemiological measures specific to the COVID-19 pandemic (protective mask, online teaching activity, social distancing) we witnessed a considerable decrease in the number of cases of respiratory viroids in children. With the lifting of prophylactic measures that coincided with the start of physical teaching activities and the onset of the cold season, we have been confronted in pediatric wards with an increase in the incidence of virological infections in the pediatric population. In this article we aim to analyze the particularities of respiratory virological diseases in children in the season 2022 - 2023 both from the etiological and epidemiological point of view and the characteristic clinical forms of the disease. We conducted a retrospective clinical study of cases admitted to the Clinical Departments of Infectious DiseasesPediatrics of the National Institute of Infectious Diseases “Prof. Dr. Matei Bals” in the period October 2022 - March 2023. During this period, we recorded 3.012 cases of respiratory virology in children, which represents the majority of pediatric pathology admitted (72,9 %). The peak incidence of respiratory virology occurred in December (688 cases). From the etiological point of view, most cases were SARS-CoV-2 infections, followed by influenza (predominantly type A), then a smaller number of infections with respiratory syncytial virus (RSV), rhinovirus, adenovirus, metapneumovirus. The most common clinical form of the disease was moderate (66.9%), with severe forms accounting for 10.5%. All pediatric cases of respiratory virology admitted to our wards have evolved favorably, with no deaths. [ABSTRACT FROM AUTHOR]

[Display omitted] • PEGylated phenothiazine imines were synthetized via microwave assisted synthesis. • The novel imines proved high quantum efficiency in solution and solid state. • They showed reversible switch of their fluorescence under external stimuli. • PEG was beneficial for improving the solubility and quantum efficiency. Herein we report the synthesis, characterization, photophysical behavior and dynamic character of new PEGylated imine derivatives. Two PEGylated phenothiazine aldehydes were synthetised and reacted with two amines bearing sulfonamide moiety via microwave assisted synthesis to yield four imine derivatives. The imines and the aldehydes precursors were structurally characterized by NMR and FTIR spectroscopy and their self-assembly behaviour was investigated by polarized light microscopy (POM) and dynamic light scattering (DLS). Photophysical properties were investigated by UV–vis and photoluminescence spectroscopy and the quantum efficiency was determined using an integrating sphere. Dynamic character of the imine derivatives was explored by NMR and UV–vis spectroscopy in correlation with visual assessment of luminescence change. The new synthetized PEGylated imines showed solubility and stability in common organic solvents, high quantum efficiency in solution and solid state, self-assembling behaviour in ethanol, and dynamic character giving access to the reversible switch of their emission colour from green to yellow through shifting the imination equilibrium under the influence of external stimuli. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 infection is usually a self-limiting viral infection in healthy children. Still, it’s effects on the neonatal population remain largely unknown. There has been evidence of adverse events on neonates, mostly consisting in case reports of patients with severe forms of COVID-19 and also recent cohort studied of the pediatric population including the neonatal subgroup. The clinical presentation appears different in the neonatal patients in contrast with older children, and may manifest also as a life-threatening respiratory infection with systemic complications. In this paper we present a clinical case of a premature boy with a corrected age of 40 weeks at admission to the Pediatric Infectious Diseases Clinical Department IX of the National Institute of Infectious Diseases “Prof. Dr. Matei Bals” with the diagnosis of SARS-CoV-2 infection. The positive diagnosis was established on suggestive clinical picture (fever, dry couch, rhinorrhea, loose stools and inappetence) and confirmed by SARS-CoV-2 rapid antigen test. Laboratory investigations at admission showed only moderate to severe anemia, mild inflammatory syndrome and a mild neonatal hyperbilirubinemia, with normal leukocyte count, normal glycaemia, ionograme and blood gases. Chest x-ray showed moderate interstitial pneumonia. In the second day of admission, after 24h of favorable evolution, with no fever and present appetite, he suddenly presented during defecation a presumptive vasovagal syndrome, with general hypotonia and a short period of desaturation. Laboratory investigations made during the episode showed normal glycaemia, normal ionograme, normal blood gases, moderate-severe anemia and important metabolic acidosis. A new chest x-ray showed evolution of the interstitial pneumonia. We did a blood transfusion and continued antiviral treatment, antibiotic treatment and perfusions. He maintained normal pulmonary and cardiac function for another 6 hours, after which he presented a tonic-clonic seizure and after administration of intrarectal benzodiazepines he presented cardio-pulmonary arrest. He was resuscitated, intubated and sedated and transfer to a children ICU. 2 weeks later after admission in the ICU he was discharged with favorable outcome. The case presented shows that although SARS-CoV-2 infection is often a mild condition in children, COVID-19 in neonates can have an unpredicted course. Rapid evolution to sever forms can be a possible disease outcome. Preterm birth with associated complications like bronchodysplasia or anemia, can predispose to sever evolution of the disease, and this child must be kept safe. There is also a neurotropic potential of the SARS-CoV-2 virus that has to be followed. [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]

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]

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]

This paper focuses on the preparation of chitosan-based nanofibers embedding copper oxide nanoparticles to create multifunctional materials that meet the demands of contemporary applications. To this end, a mixture of chitosan, quaternized chitosan and poly (ethylene glycol) was used as polymeric matrix, considering their own contribution to the final material's properties and their ability to stabilize the copper oxide nanoparticles. An exhaustive investigation of the nanofibers was done in order to assess their composition and morphology (FTIR, 1H NMR, WXRD, TGA, SEM, TEM, POM, UV–vis) and to study their mechanical, antimicrobial and antioxidant properties, air and water permeability and ability for air filtration. It was shown that the copper oxide nanoparticles were anchored into the polymeric matrix via strong hydrogen bonding and electrostatic interactions, which induced the improvement of the mechanical properties and antioxidant activity. The copper oxide nanoparticles favored the thinning of the fibers during electrospinning process and improved the antibacterial activity and dust filtration capacity. Besides, the fibers displayed air permeability and vapor water transmission rate similar to synthetic nanofibers, while being biodegradable. All these performances recommend the new materials for developing antibacterial eco-materials with good breathability to be used as hygienic textiles, masks, or air filters. [Display omitted] Chitosan nanofibers encapsulating copper oxide nanoparticles by needleless electrospinning High antioxidant and antimicrobial activity Tunable air permeability, vapor water transmission rate and dedusting ability High mechanical properties and soil biodegradability [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 paper reports new chitosan-based nanofibers, designed to address the healing of burn wounds. To this aim, mesoporous chitosan fiber mats were prepared by electrospinning using poly(ethylene oxide) as sacrificial additive, followed by loading with norfloxacin and coating with an antifungal agent via dynamic imine bonds. Dynamic vapor sorption experiment proved intra-fiber mesopores around 2.7 nm, and UV–vis, FTIR, and NMR spectroscopy confirmed the norfloxacin embedding and the imination reaction. SEM, AFM and POM techniques displayed semicrystalline nanofibers with average diameter around 170 nm entangled into a non-woven mat. Their mesoporous nature favored a rapid adsorption of fluids up to 17 g/g, and a biodegradation rate fitting the wound healing rate, i.e. up to 30 % mass loss in media of pH characteristic to wound exudate and total degradation in that characteristic to normal dermis. The composite fibers released the NFX and 2FPBA in a controlled manner, and showed antimicrobial activity against gram positive, gram negative and fungal strains. They had no cytotoxic effect on normal human dermal fibroblasts, and showed biocompatibility on experimental rats. The investigation of wound healing ability on second/third-degree burn model in rats revealed wound closure and total restoration of the fully functional dermis and epidermis. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper aimed to prepare quaternary chitosan-based nanofibers as bioabsorbable wound dressings. To this aim, fully biodegradable chitosan/ N,N,N -trimethyl chitosan (TMC) nanofibers were designed and prepared via electrospinning, using poly(ethylene glycol) as sacrificial additive. The new biomaterials were structurally and morphologically characterized by FTIR and NMR spectroscopy, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy, and their properties required for wound dressings application were investigated and discussed in detail. Thus, the nanofiber behavior was investigated by swelling, dynamic vapor sorption, and in vitro biodegradation in media mimicking the wound exudate. The mechanical properties were analysed from the stress-strain curves, the bioadhesivity from the texture analysis and the mucoadhesivity from the Zeta potential and transmittance measurements. The antimicrobial activity was assessed against S. aureus and E. coli strains, and the biocompatibility was tested in vitro on normal human dermal fibroblasts, and in vivo on rats. The application of the fiber mats with the best balance of properties as dressings on deep burn wound models in rats showed wound closure and active healing, with fully restoration of epithelia. It was concluded that the combination of chitosan with TMC into nanofibers provides new potential bioabsorbable wound dressing, opening new perspectives in regenerative medicine. [Display omitted] • Chitosan/TMC nanofibers were prepared by electrospinning using PEO as sacrificial additive. • They had strong antimicrobial activity, while being in vitro and in vivo biocompatible. • In wet media, they presented high swelling, fluid exchange and biodegradability. • They had good muco- and bio-adhesiveness and mechanical properties similar to skin. • Applied on burn wounds in rats, they favored rapid healing and fully tissue restoration. [ABSTRACT FROM AUTHOR]

Microbial infections are a serious healthcare related problem, causing several complications and even death. That is why, the development of new drug delivery systems with prolonged effect represents an interesting research topic. This study presents the synthesis and characterization of new hydrogels based on chitosan and three halogenated monoaldehydes. Further, the hydrogels were used as excipients for the development of drug delivery systems (DDS) by the incorporation of fluconazole, an antifungal drug. The systems were structurally characterized by Fourier Transformed Infrared Spectroscopy and Nuclear Magnetic Resonance, both methods revealing the formation of the imine linkages between chitosan and the aldehydes. The samples presented a high degree of ordering at supramolecular level, as demonstrated by WXRD and POM and a good water-uptake, reaching a maximum of 1.6 g/g. The obtained systems were biodegradable, loosing between 38 and 49 % from their initial mass in the presence of lysozyme in 21 days. The ability to release the antifungal drug in a sustained manner for seven days, along with the high values of the inhibition zone diameter, reaching a maximum of 64 mm against Candida parapsilosis for the chlorine containing sample, recommend these systems as promising materials for bioapplications. [ABSTRACT FROM AUTHOR]

Chitosan based nanofibers are emerging biomaterials with a plethora of applications, especially in medicine and healthcare. Herein, binary quaternized chitosan/chitosan fibers are reported for the first time. Their preparation strategy consisted in the electrospinning of ternary chitosan/quaternized chitosan/poly(ethylene oxide) solutions followed by the selective removal of poly(ethylene oxide). Their morphology and performances were systematically investigated and discussed in detail. It was found that the fibers had reversible water vapor adsorption/desorption and showed swelling degrees similar to commercial wound dressings. They presented good mechanical properties and the content of quaternized chitosan modulated their bioadhesion, mucoadhesion and biodegradation rate and conferred them strong antimicrobial activity. Tests on normal human fibroblasts confirmed their safely use in contact with tissues and the biocompatibility investigation on rats showed no harmful effect when subcutaneous implanted. All these proved the binary quaternized chitosan/chitosan fibers as bioactive materials suitable for tissue regeneration, wound healing and drug delivery systems. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study reports the synthesis and characterization of 12 drug delivery systems (DDS) for the co-delivery of antifungal and antiviral agents. The systems were obtained by an in situ hydrogelation method of 6 chitosan oligomers with values of the polymerization degree between 14 and 51, with 2-formylphenylboronic acid, in the presence of tenofovir. The structural characterization by NMR and FTIR spectroscopy demonstrated the formation of imine linkages, while WXRD revealed the 3D layered architecture of the systems. SEM and POM images demonstrated the uniform distribution of tenofovir into the matrix, while the Zeta potential measurements revealed the strong interactions which develop between system components. The obtained DDSs presented biodegradability, hemocompatibility and in vivo biocompatibility, which along with their ability to release both the drug and the antifungal aldehyde make them promising materials for the treatment of HIV infection and its associated co-infections' symptoms. [Display omitted] [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is a lethal brain cancer with a very difficult therapeutic approach and ultimately frustrating results. Currently, therapeutic success is mainly limited by the high degree of genetic and phenotypic heterogeneity, the blood brain barrier (BBB), as well as increased drug resistance. Temozolomide (TMZ), a monofunctional alkylating agent, is the first line chemotherapeutic drug for GBM treatment. Yet, the therapeutic efficacy of TMZ suffers from its inability to cross the BBB and very short half-life (~2 h), which requires high doses of this drug for a proper therapeutic effect. Encapsulation in a (nano)carrier is a promising strategy to effectively improve the therapeutic effect of TMZ against GBM. Although research on liposomes as carriers for therapeutic agents is still at an early stage, their integration in GBM treatment has a great potential to advance understanding and treating this disease. In this review, we provide a critical discussion on the preparation methods and physico-chemical properties of liposomes, with a particular emphasis on TMZ-liposomal formulations targeting GBM developed within the last decade. Furthermore, an overview on liposome-based formulations applied to translational oncology and clinical trials formulations in GBM treatment is provided. We emphasize that despite many years of intense research, more careful investigations are still needed to solve the main issues related to the manufacture of reproducible liposomal TMZ formulations for guaranteed translation to the market. [ABSTRACT FROM AUTHOR]

The paper reports hydrogels prepared from chitooligosaccharides with different polymerization degrees (14 to 51), by crosslinking with 2-formylphenylboronicacid in three molar ratios of their functionalities. The structural, morphological and supramolecular characterization confirmed a hydrogelation mechanism based on self-assembling of newly formed imine units and porous morphology. Rheological measurements confirmed the formation of thixotropic hydrogels, and swelling tests indicated mass equilibrium swelling values up to 25 in water and 9 in phosphate buffer saline. The monitoring of enzymatic degradability demonstrated the enhancing of biodegradation rate as long as the polymerization degrees of the oligomers decreased, the mass loss increasing from 16% to 43%. In vivo and ex-vivo biocompatibility investigation on experimental mice showed no cytotoxic effect, and in vitro antimicrobial tests revealed remarkable antimicrobial properties on nine strains, with a maximum inhibition diameter of 49 mm on Aspergilius brasiliensis and very good results on Cladosporium cladosporioides , Penicillium crysogenum and different Candida species. [Display omitted] [ABSTRACT FROM AUTHOR]

Microporous chitosan nanofibers functionalized with different amounts of an antimicrobial agent via imine linkage were prepared by a three-step procedure including the electrospinning of a chitosan/PEO blend, PEO removal and acid condensation reaction in a heterogeneous system with 2-formylphenylboronic acid. The fibers' characterization was undertaken keeping in mind their application to wound healing. Thus, by FTIR and 1H-NMR spectroscopy, it was confirmed the successful imination of the fibers and the conversion degree of the amine groups of chitosan into imine units. The fiber morphology in terms of fiber diameter, crystallinity, inter- and intra-fiber porosity and strength of intermolecular forces was investigated using scanning electron microscopy, polarized light microscopy, water vapor sorption and thermogravimetric analysis. The swelling ability was estimated in water and phosphate buffer by calculating the mass equilibrium swelling. The fiber biodegradation was explored in five media of different pH, corresponding to different stages of wound healing and the antimicrobial activity against the opportunistic pathogens inflicting wound infection was investigated according to standard tests. The biocompatibility and bioadhesivity were studied on normal human dermal fibroblast cells by direct contact procedure. The dynamic character of the imine linkage of the functionalized fibers was monitored by UV-vis spectroscopy. The results showed that the functionalization of the chitosan microporous nanofibers with antimicrobial agents via imine linkage is a great route towards bio-absorbable wound dressings with "on demand" antimicrobial properties and biodegradation rate matching the healing stages. [ABSTRACT FROM AUTHOR]

The paper reports the preparation and characterization of a series of functionalized chitosan nanofibers designed for tissue engineering. Their functionalization was done by imination with two aldehydes with complementary bioactivity, one possessing antimicrobial activity and the other one having potential to enhance it by improving the cell permeability. The degree of imination of the fibers and the dynamic character of the imine units were investigated by FTIR, 1H NMR and UV–vis spectroscopy, while their morphology was assessed by scanning electron microscopy and polarized light microscopy. The swelling ability and biodegradation were determined in conditions mimicking the physiological environment, i.e. saline buffer and lysozyme medium at 37 °C. Preliminary biocompatibility and antimicrobial properties were evaluated by MTS assay on normal human dermal fibroblasts, and by disk diffusion method against relevant bacterial and fungal reference strains. The fibers showed fast swelling, biodegradation in the presence of lysozyme, biocompatibility and antimicrobial activity. It was concluded that the imination of chitosan nanofibers with two different aldehydes is a promising route towards biomaterials with improved properties for tissue engineering. [Display omitted] • Double functionalized chitosan nanofibers were prepared by imination with two aldehydes. • They showed aldehyde release due to the dynamic character of the imine bonds. • The double imination was a useful tool to control the swelling and biodegradation rate. • The new biomaterials are biocompatible and have antimicrobial properties. [ABSTRACT FROM AUTHOR]