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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 paper focuses on the preparation of phenothiazine based nanoparticles, both in liquid and solid states, by reprecipitation in water and solvent induced phase separation respectively. Polymethylmethacrylate was used as an inert matrix and polyfluorene as a luminescent matrix. The morphological features of the nanoparticles were investigated by dynamic light scattering, and SEM, AFM and POM microscopy, which revealed their supramolecular ordering as nanocrystals. Their photophysical behaviour was monitored by UV–vis and photoluminescence spectroscopy. The nanocrystals emitted green light, with higher efficiency compared to the bulk crystals, reaching an absolute quantum yield of 35% in water, 45% in polymethylmethacrylate, and 39% in polyfluorene. [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]

A series of chiral hydrogels was prepared from a homogeneous mixture of chitosan and betulinic aldehyde in different molar ratios, under the effect of ultrasound. The hydrogelation mechanism has been investigated by FTIR and CD spectroscopy, wide angle X-ray diffraction and polarized light microscopy. The morphology of hydrogels was examined by SEM. The swelling ability has been tested in three media of different pH. It was concluded that hydrogelation occurred by different pathways, closely related to the peculiarities of the chitosan-betulin systems. Circular dichroism measurements revealed chiroptical properties of the hydrogels, correlated to their content and crosslinking pathway. [ABSTRACT FROM AUTHOR]

A series of hydrogels based on chitosan polyamine and nitrosalicylaldehyde were prepared via dynamic covalent chemistry (DCC), by imination and transimination reactions towards ordered clusters which play the role of crosslinking nodes of the chitosan network. The hydrogelation mechanism has been proved through NMR and FTIR spectroscopy, X-ray diffraction and polarized light microscopy. The successful preparation of the hydrogels and their mechanical properties were further investigated using rheological measurements. By electron scanning microscopy, the hydrogels exhibited a channels microstructure morphology which critically influenced their fast swelling by capillarity. The hydrogels cytotoxicity was explored in vitro on HeLa cancer cells and their biocompatibility was monitored in vivo by subcutaneous implantation on rats. The novel hydrogels proved good in vitro cytotoxicity on the HeLa cells and also in vivo biocompatibility in rats. Thus, these novel biomaterials promise to be suitable for local cancer therapy. [ABSTRACT FROM AUTHOR]

A series of poly(azomethine-phenothiazine)s was synthesized by using the reaction of 10-methyl-phenothiazine-3,7-dicarbaldehyde with diamines containing fluorene chromophore or polyethylene glycol (PEG) flexible spacer. The polymers were structurally characterized by 1 H NMR and FTIR spectral techniques, elemental analysis and wide angle X-ray diffraction. Their thermal properties were monitored by using variable temperature polarized light microscopy whilst their photophysical behaviour was demonstrated by using UV–vis absorption and photoluminescence spectroscopy. All of these polymers were found to emit green light with high quantum yield, in both solution and solid state. The emission efficiency in solid state was further improved by mixing the fluorene containing polymers with the PEG containing one, when continuous films with quantum efficiency of up to 16% were obtained. [ABSTRACT FROM AUTHOR]

The paper focusses on the synthesis of novel hydrogels by joining natural biodegradable compounds with the aim to achieve biocompatible materials for bio related applications. The hydrogels were prepared from chitosan and citral by constitutional dynamic chemistry, incorporating both molecular and supramolecular dynamic features. The hydrophobic flexible citral has been reversible immobilized onto the hydrophilic chitosan backbone via imine bonds to form amphiphilic glycodynamers, which further self-ordered through supramolecular interactions into a 3D-network of biodynameric hydrogel. The synthetic pathway has been demonstrated by NMR and FTIR spectroscopy, X-ray diffraction and polarized light microscopy. Studies of the hydrogel morphology revealed a 3D porous microstructure, whose pores size correlated with the crosslinking degree. Rheological investigations evidenced high elasticity, thermo-responsiveness and thixotropic behavior. As a proof of the concept, the hydrogels proved in vivo biocompatibility on laboratory mice. The paper successfully implements the constitutional dynamic chemistry in generation of chitosan high performance hydrogels. [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]

A series of seven low molecular weight compounds containing triazole, pyridine-N-oxide, and one substituted aromatic ring linked together by heteroatoms containing spacers was synthesized by click chemistry reaction. The compounds were structurally characterized by FTIR, NMR, as well as single-crystal X-ray diffraction. Their morphologic, thermotropic, and photophysical properties were determined by dynamic light scattering, scanning electron microscopy, atomic force microscopy, polarized light microscopy, UV-vis, and photoluminescence spectroscopy. The triazole derivatives proved to have porous 3D supramolecular architectures determined by an extensive nonclassical hydrogen bonding network. They spontaneously crystallized into long nanofibers and exhibited typical molecular glass behavior, aggregation induced emission as well as crystallization induced emission enhancement. [ABSTRACT FROM AUTHOR]

Chitosan based hydrogels are a class of cross-linked materials intensely studied for their biomedical, industrial and environmental application, but their biomedical use is limited because of the toxicity of different organic crosslinkers. To overcome this disadvantage, a new strategy to produce supramolecular chitosan hydrogels using low molecular weight compounds able to form covalent linkages and H-bonds to give a dual crosslinking is proposed. For this purpose we used 2-formylphenylboronic acid, which brings the advantage of imine stabilization via iminoboronate formation and potential antifungal activity due to the presence of boric acid residue. FTIR and NMR spectroscopy indicated that the gelling process took place by chemo-physical crosslinking forming a dual iminoboronate-chitosan network. Further, X-ray diffraction demonstrated a three-dimensional nanostructuring of the iminoboronate network with consequences on the micrometer-scale morphology and on the improvement of mechanical properties, as demonstrated by SEM and rheological investigation. The hydrogels proved strong antifungal activity against Candida planktonic yeasts and biofilms, promising to be a friendly treatment of the recurrent vulvovaginitis infections. [ABSTRACT FROM AUTHOR]

A smectogen liquid crystal based on benzoate units has been synthesized and structurally characterized by FTIR and 1 H NMR spectroscopy. Besides, its structure and supramolecular arrangement in the crystalline state was demonstrated by single crystal X-ray diffraction measurements. The thermotropic behaviour, monitored by differential scanning calorimetry and polarized light microscopy, consists in the formation of an enantiotropic smectic mesophase with a direct first order transition from the isotropic to smectic mesophase, and with its thermal stability range superposed on human body temperature. The smectogen liquid crystal has moderate wettability – suitable for biocompatible materials and presents good antipathogenic activity against gram positive and gram negative bacteria and fungus. All these properties recommend the understudied liquid crystal to be used in biochemical and biological applications. [ABSTRACT FROM AUTHOR]

Fifteen azomethine compounds based on different rigid cores and soft aliphatic tails have been designed and synthesized to generate variable supramolecular architectures with distinct thermotropic, photophysical and electrochemical properties. Ten out of the fifteen imines were grown as single crystals and their molecular structures and supramolecular architectures were determined by single-crystal X-ray diffraction. Thermotropic behavior was monitored by polarized-light microscopy and differential scanning calorimetry. Photophysical properties were studied by UV-vis and photoluminescence spectroscopy and electrochemical properties by cyclic voltammetry. It was demonstrated that all supramolecular architectures were mostly generated via weak π–π or van der Waals interactions between the rigid cores, which prompts the synthesis of molecular glasses, further giving rise to large crystals displaying an aggregation-induced emission (AIE) effect. We conclude that there is a close relationship between the molecular structures of the imines and their ability to promote favorable properties for optoelectronic applications. [ABSTRACT FROM AUTHOR]

The paper reports the preparation of twelve imino-chitosan biopolymer films by acid condensation of the amino groups of chitosan with various aldehydes, in aqueous medium, followed by slow water removal. FTIR spectroscopy has shown drastic conformation changes of chitosan macromolecular chains – from a stiff coil to a straight one, while wide angle X-ray diffraction evidenced a layered morphology of the biopolymer films. Contact angle and surface free energy determination indicated a higher biocompatibility of the new biopolymers as compared to the chitosan parent, while the microbiological screening demonstrated their self-defense properties against common and virulent pathogen agents. It was concluded that the reversibility of imine forming promotes the self-assembling of imino-chitosan biopolymer films into a lamellar morphology and, on the other hand, the slow release of the antimicrobial aldehyde in the microbiological culture. The obtained results demonstrate that chitosan polyamine is a challenging workbench to functional biodynamic materials. [ABSTRACT FROM AUTHOR]

New hybrid guest/host composite films obtained by dispersing a light-emitting azomethine dimer into three different matrix polymers have been studied. Poly(methyl methacrylate) (PMMA), UDEL polysulfone (PSU) and chitosan were chosen as host matrix. Differential scanning calorimetry, polarized light microscopy, scanning electron microscopy and atomic force microscopy measurements revealed the composite morphology and their thermal properties. UV–vis and fluorescence spectroscopy indicated the influence of polymer matrix on the azomethine dye optical properties. The composite films exhibited strong photoluminescence emission when excited with maximum absorption wavelength. It was concluded that polysulfone is a good candidate in guest/host composite obtaining. [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]

An investigation of the constitutional adaptive gelation process of chitosan/cinnamaldehyde ( C/ Cy) dynagels is reported. These gels generate timely variant macroscopic organization across extended scales. In the first stage, imine-bond formation takes place 'in-water' and generates low-ordered hydrogels. The progressive formation of imine bonds further induces 'out-of-water' increased reactivity within interdigitated hydrophobic self-assembled layers of Cy, with a protecting environmental effect against hydrolysis and that leads to the stabilization of the imine bonds. The hydrophobic swelling due to Cy layers at the interfaces reaches a critical step when lamellar self-organized hybrids are generated (24 hours). This induces an important restructuration of the hydrogels on the micrometric scale, thus resulting in the formation of highly ordered microporous xerogel morphologies of high potential interest for chemical separations, drug delivery, and sensors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Very similar low molecular Schiff bases show different solution and solid state optical, electrochemical and thermic properties. [•] The presence of a CH3 group on the aromatic increase the energy gap which hinder the electronic transitions. [•] The introduction of a methyl unit as a bulky group induce large intermolecular distances in the crystal packing. [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]

Abstract: The obtaining of bio-polymer dispersed liquid crystal (bio-PDLC) systems based on a chitosan polymer matrix is reported here for the first time. The new PDLC composites have been obtained by encapsulation of 4-cyano-4′-pentylbiphenyl (5CB) as low molecular weight liquid crystal into chitosan, and they have been characterized by polarized optical microscopy, differential scanning calorimetry, electron and transmission scanning microscopy, Raman and fluorescence spectroscopy. Submicrometric liquid crystalline droplets with uniform size distribution and density have been obtained for low liquid crystal content into the PDLCs. The droplets have a radial configuration being anchored into chitosan matrix by an interface ordering coupling phenomenon. [Copyright &y& Elsevier]

New thermotropic liquid crystalline dimers containing chromophoric units into calamitic mesogens have been synthesized and studied. Cyan, pyrrole, indole and diphenyl moieties were chosen as chromophoric units. The thermotropic behavior of the dimers was monitored by polarized light microscopy, differential scanning calorimetry, and variable temperature X-ray diffraction measurements. The photophysical properties were studied by UV-vis and photoluminescence spectroscopy. All the dimers have mesomorphic behavior and emit violet, indigo, or blue light, in solution and film. [ABSTRACT FROM PUBLISHER]

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]

The thermotropic and optical characterisations of a novel polymer dispersed liquid crystal (PDLC) system based on polysulfone UDEL P-1700 as polymer matrix and a low molecular weight liquid crystal compound containing a mesogenic azomethine core and a cyano-substituent were investigated. The PDLC samples were prepared by solvent-induced phase separation (SIPS) and thermally induced phase separation (TIPS) methods using various compositions in the two components. Information on the morphology and phase structure was obtained by polarising optical microscopy, differential scanning calorimetry and X-ray diffraction measurements. PDLC systems with well-defined droplets were obtained for the composite with medium content of liquid crystal compound. The optical characterisation of these materials was performed by analysing their UV-visible absorption and photoluminescence emission as a function of the liquid crystal aggregation degree. [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this paper was to synthesize luminescent thermotropic liquid crystalline polyazomethines containing chromophoric mesogen, which design has been addressed to optoelectronic materials. The investigation of the thermotropic behavior by three complementary methods of analyses, i.e. polarized optical microscopy, differential scanning calorimetry and wide angle X-ray diffraction, indicated a nematic mesophase for the polymers containing oxadiazole units, either alternating or random ones. A mesomorphic state maintaining the degree of order of the semicrystalline state while being viscous fluid was evidenced too. The photoluminescence spectra recorded for both polymer solutions and films exhibited a blue light emission. These results point to the possibility of obtaining monodomain or multidomain ordered thin films without grain boundaries showing good mechanical and luminescent properties. [Copyright &y& Elsevier]

The paper deals with the study of the thermotropic liquid crystalline properties of a new azomethinic symmetric dimer and some of its structural heterogeneous mixtures with one of its reagents. Their thermotropic behaviour was monitored by polarised light microscopy, differential scanning microscopy and variable temperature X-ray diffraction measurements. The influence of the structural heterogeneity on the mesomorphic behaviour was established and some similarities with the mesomorphic behaviour of the polydisperse polymers were underlined. [ABSTRACT FROM AUTHOR]

A series of copolymers containing oxadiazole and fluorene cromophores was synthesized by polycondensation of a diacid chloride incorporating one diphenylsilane linkage and a mixture of aromatic diamines containing oxadiazole and fluorene moieties. The solubility, thermal behavior, and photoluminescence ability of the thin polymer films were studied and compared with related heterocyclic polymers. These polymers are semicrystalline and form plastic mesophases in the first heating run, which brings about new ordered melted state processing opportunities. They exhibited blue photoluminescence in nanometric films, thus being promising candidates for manufacturing electroluminescent devices. [ABSTRACT FROM AUTHOR]

Thermotropic liquid crystalline polyazomethines containing 1,3,4-oxadiazole chromophors have been synthesized. These polymers are semiflexible liquid crystalline compounds containing luminescent mesogens. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide angle X-ray diffraction (WAXD) have been used to evaluate their thermal and mesomorphic properties. The target polyazomethines present liquid crystalline behavior with classical calamitic textures, large mesophase range, and high thermal stability. The investigation of the optical properties of the synthesized polymers, in solution and solid state, confirmed a blue fluorescence. [ABSTRACT FROM AUTHOR]

Azomethine liquid crystals (LCs), constituted by symmetric and asymmetric bithiophene or fluorene units as chromophores, were designed and synthesised. Their thermotropic behaviour was investigated using optical microscopy, differential scanning calorimetry, and wide angle X-ray diffraction. A lowering of transition temperatures was obtained by the introduction of the lateral methyl group as compared with unsubstituted compounds. The observed LC phases possess the classical textures of calamitic LCs. The optical properties of the target compounds were evaluated, both in solution and in solid state. A blue fluorescence was observed for fluorene containing compounds and a green fluorescence was observed for analogous bithiophene containing compounds. The introduction of a methyl lateral group onto the aromatic rings led to a remarkable increase in the solution emission properties. [ABSTRACT FROM AUTHOR]

Abstract: A new poly(azomethine-ether) was synthesized by the reaction of bisphenol A with a thermotropic azomethine monomer, namely 4,4′-oxy-bis(4-chlorobenzylideneimino phenylene). In order to understand the influence of the molecular weight on the thermal properties, four fractions were isolated from the initial polymer. They were investigated by elemental analysis and spectroscopic methods (IR, UV, 1H NMR) and their thermal behaviour was studied by differential scanning calorimetry, optical microscopy, thermogravimetrical analysis. An increase of the thermal transition temperatures and mesophase order with increasing molecular weight was noticed. [Copyright &y& Elsevier]

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]

A series of new azomethine dimers was synthesized by the condensation reaction of flexible bis-benzaldehydes with four aromatic amines containing phenyl, naphthyl, anthracene and pyrene groups. Their right structure was confirmed by FTIR and 1H-NMR spectroscopy and their thermal properties were investigated by thermogravimetric analysis, differential scanning calorimetry and polarized light optical microscopy. A view on their photophysical behavior was gained by UV-vis and photoluminescence spectroscopy. The dimers containing pyrene and anthracene presented liquid crystalline behavior, while the other dimers were crystalline compounds. Two dimers containing pyrene moieties formed mesomorphic glasses and had intense luminescence, promising properties for applications in building optoelectronic devices. [ABSTRACT FROM AUTHOR]

The aim of the study was to create a mathematical model useful for monitoring the release of bioactive aldehydes covalently bonded to the chitosan by reversible imine linkage, considered as a polymer–drug system. For this purpose, two hydrogels were prepared by the acid condensation reaction of chitosan with the antifungal 2-formyl-phenyl-boronic acid and their particularities; influencing the release of the antifungal aldehyde by shifting the imination equilibrium to the reagents was considered, i.e., the supramolecular nature of the hydrogels was highlighted by polarized light microscopy, while scanning electron microscopy showed their microporous morphology. Furthermore, the in vitro fungicidal activity was investigated on two fungal strains and the in vitro release curves of the antifungal aldehyde triggered by the pH stimulus were drawn. The theoretical model was developed starting from the hypothesis that the imine-chitosan system, both structurally and functionally, can be assimilated, from a mathematical point of view, with a multifractal object, and its dynamics were analyzed in the framework of the Scale Relativity Theory. Thus, through Riccati-type gauges, two synchronous dynamics, one in the scale space, associated with the fungicidal activity, and the other in the usual space, associated with the antifungal aldehyde release, become operational. Their synchronicity, reducible to the isomorphism of two SL(2R)-type groups, implies, by means of its joint invariant functions, bioactive aldehyde compound release dynamics in the form of "kink–antikink pairs" dynamics of a multifractal type. Finally, the theoretical model was validated through the experimental data. [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]

A series of five eco-friendly PDLC composite films based on cholesteryl acetate liquid crystal and chitosan were obtained and characterized. The resulted composites were evaluated in terms of structure and morphology by FTIR and RAMAN spectroscopy and scanning electron microscopy, while their thermotropic behavior was evaluated by polarized optical microscopy and differential scanning calorimetry. Moreover, the contact angle and surface free energy components were measured and calculated. All the data revealed that chitosan, through the presence of hydroxyl, amine, and amide groups in its structure, has the ability to constrain the cholesteryl acetate liquid crystal to grow as radial droplets, perturbing its supramolecular chiral ordering. The size of the droplets and their density depended on the mass ratio between the polymer and the liquid crystal almost in all cases, the micrometric droplets having diameter from 5 to 8 μm, sizes which are the most recommended for optoelectronic applications. By changing the mass ratio between the components, PDLC composites with different hydrophobicity were obtained, consequence of both, their chemical composition and their geometrical microstructure of their surface. Unlabelled Image • PDLC films based on a cholesteryl acetate and chitosan were prepared. • FTIR & RAMAN spectroscopy revealed strong interactions between PDLC components. • Chitosan matrix perturbed the supramolecular chiral ordering of the liquid crystal. • The droplets had sizes lower than 10 μm and low dimensional polydispersity. [ABSTRACT FROM AUTHOR]

A series of binary phenothiazine based co-crystals were designed with the aim to reach materials with improved quantum efficiency in solid state. To this end, a host dibromine functionalized phenothiazine was mixed with a guest formyl based phenothiazine in various molar ratios, from 1:1 up to 1:9, to form single crystals and thin films as well. Single crystal X-ray diffraction, polarized light microscopy, 1H NMR and FTIR spectroscopies indicated the successful formation of supramolecular synthons via halogen bonds. Polarized light microscopy and atomic force microscopy indicated the formation of submicrometric crystals into the co-crystal films. The photophysical behaviour was investigated by UV–vis and photoluminescence spectroscopies, and showed a remarkable improvement of the quantum yield, reaching values of 27% for single co-crystals and of 42% for thin films of nano-co-crystals. Image 1 • Co-crystals were prepared from isostructural phenothiazine derivatives. • Halogen bonds were evidenced as driving forces of co-crystalization. • The quantum efficiency increased from 2% to 27% for single co-crystals and of 42% for thin films of nano co-crystals. [ABSTRACT FROM AUTHOR]

• Fluorescence functionalization of chitosans is achieved, and they are sensitive and selective to TNP and 4-NP. • The macromolecular sensors remain the sensitivity of small molecular sensors, enve improve sensitivity. • Some of the fluorescent chitosan remain the gel performance as the original chitosan. Nitroaromatic compounds, especially 2, 4, 6-trinitrophenol, have strong biological toxicity and explosive risks, so the detection of 2, 4, 6-trinitrophenol exhibit importantly practical and scientific significance. In this work, three fluorescence functionalized chitosan CNS 3 , CNS 4 and CNS 5 were prepared using chitosan as matrix. When 2, 4, 6-trinitrophenol (TNP) and/or p-nitrophenol (4-NP) was present in spot, these fluorescent chitosan sensors produced notable fluorescence quenching. It renders the chitosan sensing ability to detect TNP and 4-NP selectively and sensitively. The sensing mechanism is investigated as well. When introduced electron-rich moieties to the fluorescent chitosan, the sensitive detecting ability could be obtained. Excellent recognition ability could reach as low as 0.28 μM. The fluorescence fictionalization cause slight influence to the gel performance of chitosan. [ABSTRACT FROM AUTHOR]

• Chitosan fibers were prepared by electrospinning. • They were functionalized by imination reaction with furfural. • The as prepared furfuryl-imine-chitosan fibers showed nanoporous morphology. • They revealed high adsorption capacity for CO 2. The goal of the paper was to design a new pathway towards eco-materials suitable for CO 2 capture, by functionalization of nanoporous chitosan fibers with monoaldehydes via imination. To this end, nanoporous chitosan fibers were prepared by electrospinning and further reacted with furfural. Their morphology was investigated by SEM and AFM microscopies and revealed the formation of a network of nanoporous submicrometric fibers. The successful imination was proved by FTIR, XPS, and NMR spectroscopies. As a proof of concept, the CO 2 adsorption isotherms displayed enhanced CO 2 adsorption of the furfuryl-imine-chitosan fibers compared to pristine ones, indicating the imination of porous chitosan fibers as a feasible method to new eco-materials for CO 2 adsorption. [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]

[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]

Abstract Polymer dispersed liquid crystal (PDLC) composites were prepared by the encapsulation of cholesteryl acetate (L-ChAc) in polyvinyl alcohol boric acid (PVAB) by microemulsion technique. The supramolecular and morphological peculiarities of the resulted composites were analyzed by polarized optical microscopy, fluorescence microscopy and scanning electron microscopy respectively. The thermal behavior of the systems was evaluated by differential scanning calorimetry and the surface characteristics in terms of wettability and surface free energy were calculated based on contact angle measurements. Circular dichroism was further used to evidence the chiroptical properties of the studied PDLCs and to have an insight on the potential interactions between the components. The ability of the composites to act as sensors for different blood analytes was preliminary tested by POM. The results indicated that PVAB facilitated a uniform distribution of the cholesteric liquid crystal as micrometric droplets with narrow polydispersity and planar anchoring. The obtained PDLCs proved moderate wettability and they showed a selective responsiveness for L or D sugars, amino acids and DNA. All these results indicated the new polymer dispersed liquid crystal systems as promising materials for biosensors building. Graphical abstract Unlabelled Image Highlights • PDLC films based on a cholesteric liquid crystal and a PVAB matrix were prepared. • The liquid crystal was anchored into the matrix as microdroplets (diameter of 5 μm). • The PDLC films showed a helical supramolecular architecture. • They revealed responsiveness to various biologic analytes. [ABSTRACT FROM AUTHOR]

A series of drug delivery systems were prepared by chitosan hydrogelation with citral in the presence of an antineoplastic drug: 5-fluorouracil. The dynamic covalent chemistry of the imine linkage allowed the obtaining of supramolecular tridimensional architectures in which the drug has been homogenously dispersed. Fourier-transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WXRD) and polarized light microscopy (POM) measurements were used in order to follow the hydrogelation and drug encapsulation processes. The ability of the prepared systems to release the drug has been investigated by UV-Vis spectroscopy using a calibration curve and by fitting the results with different mathematic models. To mimic the behavior of the hydrogel matrix in bio-environmental conditions in view of applications, their enzymatic degradability was monitored in the presence of lysozyme. The in vivo side effects of the systems, in terms of their influence on the blood elements, biochemical and immune parameters were monitored on white Swiss mice by intraperitoneal administration of the injectable obtained hydrogels. All the characteristics of the obtained systems, such as micro-porous morphology, uniform drug encapsulation, enzymatic degradability, lack of side effects, other than the one of the drug itself, along with their ability to release the drug in a sustained manner proved that these material meet the requirements for the development of drug delivery systems, making them suitable for being applied in intraperitoneal chemotherapy. [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]

A series of drug delivery systems were prepared by chitosan hydrogelation with citral in the presence of an antineoplastic drug: 5-fluorouracil. The dynamic covalent chemistry of the imine linkage allowed the obtaining of supramolecular tridimensional architectures in which the drug has been homogenously dispersed. Fourier-transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WXRD) and polarized light microscopy (POM) measurements were used in order to follow the hydrogelation and drug encapsulation processes. The ability of the prepared systems to release the drug has been investigated by UV-Vis spectroscopy using a calibration curve and by fitting the results with different mathematic models. To mimic the behavior of the hydrogel matrix in bio-environmental conditions in view of applications, their enzymatic degradability was monitored in the presence of lysozyme. The in vivo side effects of the systems, in terms of their influence on the blood elements, biochemical and immune parameters were monitored on white Swiss mice by intraperitoneal administration of the injectable obtained hydrogels. All the characteristics of the obtained systems, such as micro-porous morphology, uniform drug encapsulation, enzymatic degradability, lack of side effects, other than the one of the drug itself, along with their ability to release the drug in a sustained manner proved that these material meet the requirements for the development of drug delivery systems, making them suitable for being applied in intraperitoneal chemotherapy. [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]