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The present study describes a comprehensive investigation of the spectroscopic characteristics, stability and in vitro antioxidant and cytotoxic properties of the Flavin MonoNucleotide (FMN) and Flavin Adenine Dinucleotide (FAD) in Dextran70 (Dx70) and Dx70/phospatidylcholine (PC) biomimetic systems by means of the UV–Vis absorption, fluorescence spectroscopy, chemiluminescence and Neutral Red assay. The affinity of FMN, FAD and the precursor riboflavin (RF) to an unsaturated phospholipid bilayer model as well as the location of the probes within the lipid bilayer were assessed from united-atom molecular dynamics simulations carried out on an unsaturated phospholipid bilayer model system, and the theoretical and experimental characterization of the two probes within biomembranes was complemented with the light microscopy survey of the cell morphology of L929 fibroblast cells cultivated in the presence of various dosage of FAD/FMN. In lipid bilayers, FMN/FAD resulted in a noticeable improvement of the antioxidant activity (the scavenging of reactive oxygen species up to 40%) and a significant effect on cellular viability in the L929 fibroblast cells. The results are important in the oxidative stress process concerning the redox reactions of flavins in humans as well as in further studies on different systems belonging to the category of flavoenzymes/flavoproteins, required for cellular respiration.

Angiogenesis is a physiological process involving the growth of new blood vessels, which provides oxygen and required nutrients for the development of various pathological conditions. In a tumor microenvironment, this process upregulates the growth and proliferation of tumor cells, thus any stage of angiogenesis can be a potential target for cancer therapies. In the present study, chitosan and his derivatives have been used to design novel polymer-based nanoparticles. The therapeutic potential of these newly designed nanoparticles has been evaluated. The antioxidant and MTT assays were performed to know the antioxidant properties and their biocompatibility. The in vivo antiangiogenic properties of the nanoparticles were evaluated by using a chick Chorioallantoic Membrane (CAM) model. The obtained results demonstrate that chitosan derivatives-based nanostructures strongly enhance the therapeutic effect compared to chitosan alone, which also correlates with antitumor activity, demonstrated by the in vitro MTT assay on human epithelial cervical Hep-2 tumor cells. This study opens up new direction for the use of the chitosan derivatives-based nanoparticles for designing of antiangiogenic nanostructured materials, for future cancer therapy.

The present work explores new hybrid bioactive, enzymatically degradable hydrogel nanocomposites. They are composed by stimuli-sensitive semi-interpenetrating collagen/poly(N-isopropyl acrylamide) polymeric matrix, Dellite® 67G and Cloisite® 93A nanoclays, and hydroxyapatite particles. Morphology of the hybrid hydrogel nanocomposites was examined by near infrared chemical imaging, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. It has been found that the porous hydrogel nanocomposites showed a mix between intercalated and exfoliated structure, with interconnected pores and the inorganic material was evenly distributed in the polymeric matrix because of specific interactions between components. The collagen resistance against enzymatic degradation and the thermal stability were improved due to the protein encapsulation in the synthetic polymer matrix. The hydrogel nanocomposites showed suitable swelling characteristics for tissue engineering. In vitro cytocompatibility and cell viability revealed that the hybrid nanocomposites were non-cytotoxic for rat osteoblasts. These hybrid nanocomposites were designed as potential synthetic bone tissue engineering.

The synthesis and physicochemical characterization of riboflavin (RF) loaded Myrj52–silver nanoparticles (SNPs) were performed and their cytotoxic properties were evaluated. Transmission electron microscopy analysis showed the formation of colloidal spherical SNPs with an average size of ∼12 nm. The structure, stability, dynamics and conformation of human serum albumin (HSA) binding RF on SNPs have been studied. The influence of RF on the secondary structure of HSA in the presence of SNPs showed a predominant α-helix structure (61.7%). No changes induced by RF binding to HSA were observed. The cytotoxicity of RF and RF–HSA loaded Myrj52–SNPs was evaluated in vitro using the Neutral Red assay and cell morphology observations in a culture of L929 fibroblast cells. The results have relevance with regard to the RF loaded Myrj52–SNP formulation for pharmaceuticals.

The work aims to simulate in vitro, the antioxidant activity of riboflavin (RF) (Vitamin B2) in Polyethylene Glycols (PEGs) (Tween20 and Myrj52)/Bovine Serum Albumin (BSA) systems, using the chemiluminescent system luminol-hydrogen peroxide, in alkaline solution, Tris–HCl buffer, pH 8.5. The tested concentrations were 2–20 μM for RF and 0.06 to 0.6% for PEGs. It was found that 0.12% PEGs enhance the antioxidant activity of RF to higher and lower values, according to their molecular structure, Tween20 > Myrj52. RF has a pro-oxidant effect in the presence of BSA, while in the PEG/BSA systems, its antioxidant activity increases up to ~20%; a cross-linking of PEG to RF in the presence of BSA is considered. Additionally, studies by fluorescence spectroscopy on RF embedded in Tween20/BSA system-enhanced Tyrosine fluorescence contribution. In vitro cytotoxicity evaluation of RF in PEG/BSA systems was performed by Neutral Red assay and by monitoring lactate dehydrogenase release. PEG/BSA system offers great promise for enhancement of the RF antioxidant activity and biocompatibility, maintaining the integrity of the BSA, facts which are useful in the oxidative stress and drug delivery processes.

Chitosan is a non-toxic, biocompatible, biodegradable natural cationic polymer known for its low imunogenicity, antimicrobial, antioxidant effects and wound-healing activity. To improve its therapeutic potential, new chitosan-sulfonamide derivatives have been designed to develop new wound dressing biomaterials. The structural, morphological and physico-chemical properties of synthesized chitosan derivatives were analyzed by FT-IR, (1)H NMR spectroscopy, scanning electron microscopy, swelling ability and porosity. Antimicrobial, in vivo testing and biodegradation behavior have been also performed. The chitosan derivative membranes showed improved swelling and biodegradation rate, which are important characteristics required for the wound healing process. The antimicrobial assay evidenced that chitosan-based sulfadiazine, sulfadimethoxine and sulfamethoxazole derivatives were the most active. The MTT assay showed that some of chitosan derivatives are nontoxic. Furthermore, the in vivo study on burn wound model induced in Wistar rats demonstrated an improved healing effect and enhanced epithelialization of chitosan-sulfonamide derivatives compared to neat chitosan. The obtained results strongly recommend the use of some of the newly developed chitosan derivatives as antimicrobial wound dressing biomaterials.

Tuberculostatic drugs are the most common drug groups with global hepatotoxicity. Awareness of potentially severe hepatotoxic reactions is vital, as hepatic impairment can be a devastating and often fatal condition. The treatment problems that may arise, within this class of medicines, are mainly of two types: adverse reactions (collateral, toxic or hypersensitive reactions) and the initial or acquired resistance of Mycobacterium tuberculosis to one or more antituberculosis drugs. Prevention of adverse reactions, increase treatment adherence and success rates, providing better control of tuberculosis (TB). In this regard, obtaining new drugs with low toxicity and high tuberculostatic potential is essential. Thus, in this work, we have designed or synthesized new derivatives of isoniazid (INH), such as new Isonicotinoylhydrazone (INH-a, INH-b and INH-c). These derivatives demonstrated good biocompatibility, antimicrobial property similar to that of parent isoniazid and last but not least, a significantly improved Pharmacotoxicological profile compared to that of isoniazid.

In this paper, we present the fabrication and characterization of new chitosan-based membranes while using a new biotechnology for immobilizing alkaline phosphatase (ALP). This technology involved metal ions incorporation to develop new biopolymeric supports. The chemical structure and morphological characteristics of proposed membranes were evaluated by infrared spectroscopy (FT-IR) and the scanning electron microscopy technique (SEM). The inductively coupled plasma mass spectrometry (ICP-MS) evidenced the metal ion release in time. Moreover, the effect of Mg2+ on the enzymatic activity and the antibacterial investigations while using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, hemolysis, and biocompatibility behavior were studied. Immobilizing ALP into the chitosan membranes composition followed by the incorporation of Mg2+ led to polymeric supports with enhanced cellular viability when comparing to chitosan-based membranes without Mg2+. The results obtained evidenced promising performance in biomedical applications for the new biopolymeric supports that are based on chitosan, ALP, and metal ions.