Biodegradable trimethyl chitosan nanofiber mats by electrospinning as bioabsorbable dressings for wound closure and healing.

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.

Drug delivery based on a supramolecular chemistry approach by using chitosan hydrogels.

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.

Mesoporous chitosan nanofibers loaded with norfloxacin and coated with phenylboronic acid perform as bioabsorbable active dressings to accelerate the healing of burn wounds.

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.

Antitumor Activity of PEGylated and TEGylated Phenothiazine Derivatives: Structure-Activity Relationship.

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.

Quaternized chitosan/chitosan nanofibrous mats: An approach toward bioactive materials for tissue engineering and regenerative medicine.

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.

Preparation of an Antioxidant Assembly Based on a Copolymacrolactone Structure and Erythritol following an Eco-Friendly Strategy.

The study presents the achievement of a new assembly with antioxidant behaviour based on a copolymacrolactone structure that encapsulates erythritol (Eryt). Poly(ethylene brassylate-co-squaric acid) (PEBSA) was synthesised in environmentally friendly conditions, respectively, through a process in suspension in water by opening the cycle of ethylene brassylate macrolactone, followed by condensation with squaric acid. The compound synthesised in suspension was characterised by comparison with the polymer obtained by polymerisation in solution. The investigations revealed that, with the exception of the molecular masses, the compounds generated by the two synthetic procedures present similar properties, including good thermal stability, with a Tpeak of 456 °C, and the capacity for network formation. In addition, the investigation by dynamic light scattering techniques evidenced a mean diameter for PEBSA particles of around 596 nm and a zeta potential of -25 mV, which attests to their stability. The bio-based copolymacrolactone was used as a matrix for erythritol encapsulation. The new PEBSA-Eryt compound presented an increased sorption/desorption process, compared with the PEBSA matrix, and a crystalline morphology confirmed by X-ray diffraction analysis. The bioactive compound was also characterised in terms of its biocompatibility and antioxidant behaviour.

Pegylation of phenothiazine - A synthetic route towards potent anticancer drugs.

Introduction: Cancer is a big challenge of the 21 century, whose defeat requires efficient antitumor drugs. Objectives: The paper aims to investigate the synergistic effect of two structural building blocks, phenothiazine and poly(ethylene glycol), towards efficient antitumor drugs. Methods: Two PEGylated phenothiazine derivatives were synthetized by attaching poly(ethylene glycol) of 550 Da to the nitrogen atom of phenothiazine by ether or ester linkage. Their antitumor activity has been investigated on five human tumour lines and a mouse tumor line as well, by determination of IC50. The in vivo toxicity was determined by measuring the LD50 in BALB/c mice by the sequential method and the in vivo antitumor potential was measured by the tumours growth test. The antitumor mechanism was investigated by complexation studies of zinc and magnesium ions characteristic to the farnesyltransferase enzyme, by studies of self-aggregation in the cells proximity and by investigation of the antitumor properties of the acid species resulted by enzymatic cleavage of the PEGylated derivatives. Results: The two compounds showed antitumor activity, with IC50 against mouse colon carcinoma cell line comparable with that of the traditional antitumor drugs 5-Fluorouracil and doxorubicin. The phenothiazine PEGylation resulted in a significant toxicity diminishing, the LD50 in BALB/c mice increasing from 952.38 up to 1450 mg/kg, in phenothiazine equivalents. Both compounds inflicted a 92% inhibition of the tumour growth for doses much smaller than LD50. The investigation of the possible tumour inhibition mechanism suggested the nanoaggregate formation and the cleavage of ester bonds as key factors for the inhibition of cancer cell proliferation and biocompatibility improvement. Conclusion: Phenothiazine and PEG building blocks have a synergetic effect working for both tumour growth inhibition and biocompatibility improvement. All these findings recommend the PEGylated phenothiazine derivatives as a valuable workbench for a next generation of antitumor drugs.

Chitosan crosslinking with a vanillin isomer toward self-healing hydrogels with antifungal activity.

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.

Imination of Microporous Chitosan Fibers-A Route to Biomaterials with "On Demand" Antimicrobial Activity and Biodegradation for Wound Dressings.

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.

Amphiphilic chitosan-g-poly(trimethylene carbonate) - A new approach for biomaterials design.

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.

New Insights on Hemp Oil Enriched in Cannabidiol: Decarboxylation, Antioxidant Properties and In Vitro Anticancer Effect.

This study aimed to obtain and characterize extracted hemp oil enriched in cannabidiol (CBD) by decarboxylation of cannabidiolic acid (CBDA) and to give new insights into its antioxidant and anticancer effects. Optimization of CBDA decarboxylation in hemp oil was performed, and CBD and CBDA contents and purities were determined by flash chromatography, 1H- and 13C-NMR. The antioxidant properties of CBD-enriched oil were investigated by Fe2+ chelating activity, Fe3+ reducing antioxidant power assay, O2●- scavenging activity, HO● scavenging ability and lipid peroxidation inhibitory assay, and its cytotoxicity, apoptosis- and oxidative stress-inducing effects on NHDF, MeWo, HeLa, HepG2 and HOS cells were determined. The CBD concentration in hemp oil was increased by CBDA soft decarboxylation optimized at 90 °C, for 1 h and the resulting oil was capable of reducing iron, scavenging free radicals and inhibiting lipid peroxidation in cell-free oxidative conditions. CBD-enriched oil promoted NHDF proliferation at up to 15 µg CBD/mL, while inducing apoptosis and ROS production and modulating antioxidant enzymes' gene expression in cancer cells, being selective for osteosarcoma cells, and induced apoptosis by p53- and ROS-independent mechanisms. CBD-enriched hemp oil demonstrated antioxidant properties in oxidative conditions and promoted normal fibroblasts' proliferation, while inducing apoptosis and ROS production in cancer cells.

Water soluble PEGylated phenothiazines as valuable building blocks for bio-materials.

The paper reports a series of three new PEGylated phenothiazine derivatives which keep the potential of valuable building blocks for preparing eco-materials addressed to a large realm of fields, from bio-medicine to opto-electronics. They were synthetized by connecting the hydrophilic poly(ethylene glycol) to the hydrophobic phenothiazine via an ether, ester, or amide linking group. The successful synthesis of the targeted polymers and their purity were demonstrated by NMR and FTIR spectroscopy methods. Their capacity to self-assembly in water was studied by DLS and UV-vis techniques and the particularities of the formed aggregates were investigated by fluorescence spectroscopy, SEM, AFM, POM and UV light microscopy. The biocompatibility was assessed on normal human dermal fibroblasts and human cervical cancer cells. The synthetized compounds showed the formation of luminescent aggregates and proved excellent biocompatibility on normal cells. In addition, a concentration dependent cytotoxicity against HeLa cancer cells was noticed for the PEGylated phenothiazine containing an ester unit.