Synthesis of novel chitosan-Schiff bases nanoparticles for high efficiency Helicobacter pylori inhibition.

Two chitosan Schiff bases were synthesized by condensation of chitosan with 2-(4-formylphenoxy)-N-phenylacetamide and N-(4-bromophenyl)-2-(4-formylphenoxy) acetamide denoted as Cs-SBA and Cs-SBBr, respectively. The molecular structures of the resulting chitosan derivatives were characterized using FTIR and 1HNMR and their thermal properties were investigated by TGA. These derivatives were treated with sodium tripolyphosphate (TPP) to produce Cs Schiff base nanoparticles. The nanoparticles physicochemical properties were determined by FTIR, XRD, TEM, and zeta potential analysis. The antimicrobial action against Helicobacter pylori (H. pylori) was evaluated and the results indicated that the anti-H. pylori activity had minimal inhibitory concentration MIC values of 15.62 ± 0.05 and 3.9 ± 0.03 µg/mL for Cs-SBA and Cs-SBBr nanoparticles (Cs-SBA NPs and Cs-SBBr NPs), respectively. The better biologically active nanoparticles, Cs-SBBr NPs, were tested for their cyclooxygenases (COX-1 and COX-2) inhibitory potential. Cs-SBBr NPs demonstrated COX enzyme inhibition activity against COX-2 (IC50 4.5 ± 0.165 µg/mL) higher than the conventional Indomethacin (IC50 0.08 ± 0.003 µg/mL), and Celecoxib (IC50 0.79 ± 0.029 µg/mL). Additionally, the cytotoxicity test of Cs-SBBr NPs showed cytotoxic effect on Vero cells (CCL-81) with IC50 = 17.95 ± 0.12 µg/mL which is regarded as a safe compound. Therefore, Cs-SBBr NPs may become an alternative to cure H. pylori and prevent gastric cancer.

Synthesis and biological evaluation against H. pylori of chitosan menthone Schiff base hybrid with different types of inorganic nanoparticles.

The production of novel natural medicines for the treatment of Helicobacter pylori (H. pylori) has lately attracted a lot of interest. Some bacterial infections have traditionally been alleviated by terpenes. The present work intended to examine the impact of several chitosan menthone Schiff base nanocomposites on the treatment of H. pylori infection as well as on its anti-inflammatory capacity. Chitosan (Cs) was condensed with menthone with different molar ratios of Cs:menthone (1:0.5, 1:1, and 1:2) to produce chitosan Schiff bases namely; Cs-SB1, Cs-SB2, and Cs-SB3, respectively. Cs-SB3 Schiff base nanocomposites were prepared individually by adding 2%Ag, 2%Se, (1%Ag + 1%Se), and 2%Fe2O3 nanoparticles to produce compounds denoted as Cs-SB-Ag, Cs-SB-Se, Cs-SB-Ag/ Se, and Cs-SB-Fe, respectively. The anti-H. pylori activity of Cs-SB-Se was detected at a minimal inhibitory concentration MIC of 1.9 µg/mL making it the most biologically active compound in our study. Cs-SB-Se nanocomposite was tested for its cyclooxygenases (COX-1 and COX-2) inhibitory potential which demonstrated inhibitory efficacy towards COX enzymes with inhibition value against COX-1 (IC50 = 49.86 ± 1.784 µg/mL) and COX-2 (IC50 = 12.64 ± 0.463 µg/mL) which were less than the well-known Celecoxib (22.65 ± 0.081 and 0.789 ± 0.029 µg/mL) and Indomethacin (0.035 ± 0.001 and 0.08 ± 0.003 µg/mL) inhibitors. The selectivity index SI = 3.94 for tested nanocomposites indicated higher selectivity for COX-1. The cytotoxicity of the Cs-SB-Se nanocomposite was evaluated in Vero cells (CCL-81) and it showed that at a concentration of 62.5 µg/mL, cell viability was 85.43 %.

Synthesis and characterization of poly(3-hydroxybutyrate)/chitosan-graft poly (acrylic acid) conjugate hyaluronate for targeted delivery of methotrexate drug to colon cancer cells.

Anti-cancer medications that are delivered specifically to the tumor site possess greater efficacy with less negative effects on the body. So, the current research relies on a novel method for intercalating the anticancer medication methotrexate in poly(3-hydroxybutyrate)/chitosan-graft poly (acrylic acid) conjugated with sodium hyaluronate. The graft copolymers were synthesized through persulfate-initiated grafting of acrylic acid onto a binary mixture of various amounts of chitosan and poly(3-hydroxybutyrate) (2/1, 1/1 and 1/2, w/w) using microwave irradiation. The graft copolymer was conjugated with sodium hyaluronate for targeted delivery of methotrexate drug specifically to colon cancer cell lines (Caco-2). The graft copolymers were characterized by many physical techniques. The maximum drug loading efficiency was observed in case of the graft copolymer/hyaluronate rich in chitosan content 69.7 ± 2.7 % (4.65 mg/g) with a sustained release about 98.6 ± 1.12 %, at pH 7.4. The findings of severe cytotoxicity having a value of the IC50 of 11.7 µg/ml, a substantial proportion of apoptotic cells (67.88 %), and an elevated level of DNA breakage inside the treated Caco-2 cells verified the effective release of methotrexate from the loaded copolymer matrix. Besides, the high stability and biological activity of the released drug was exhibited through occurrence of greater increment of reactive oxygen species and effect on the extent of expression of genes connected to apoptosis and anti-oxidant enzymes within the treated cells. Ultimately, this system can be recommended as potent carrier for methotrexate administration to targeted cancerous cells in the colon.

Synthesis and characterization of hydrogel-based magnetite nanocomposite adsorbents for the potential removal of Acid Orange 10 dye and Cr(VI) ions from aqueous solution.

Magnetic responsive hydrogels (CMX-cl-P4VP/M-NPs) were successfully synthesized through in situ co-precipitation procedure and investigated using various techniques. The surface morphology analysis revealed that the M-NPs were uniformly distributed within the hydrogel matrix and had average sizes ranging from 4.98 to 15.02 nm. The graft copolymer containing nanoparticles exhibited a sensitive magnetic response, and their recovery could be facilitated by applying a magnetic field. The purpose of this research is to study the ability of the prepared magnetic hydrogel to remove AO-10 dye and hexavalent chromium ions (Cr(VI)) from the aqueous solution under various factors, namely contact time, pH, amount of adsorbent, coexisting ions and AO-10 and Cr(VI) concentrations. The outcomes of the batch adsorption demonstrated that the adsorbent hydrogel incorporated with a low percentage (10 %) of M-NPs had a strong affinity for the removal of AO-10 dye and Cr(VI) ions at an optimum pH = 3, and the removal percentage reached 99.3 and 97.4 % for 500 mg L-1 and 300 mg L-1 of AO-10 dye and Cr(VI) ions within 90, 50 min, respectively. The data were well-fitted by pseudo-first-order kinetics. The maximum adsorption capacities of AO-10 dye and Cr(VI) ions onto adsorbent were 2448 and 574.7 mg g-1 at 298 K, calculated from the Langmuir model.

Study of Ag Nanoparticles in a Polyacrylamide Hydrogel Dosimeters by Optical Technique.

The dosimetric characteristics of hydrogel dosimeters based on polyacrylamide (PAC) as a capping agent incorporating silver nitrate as a radiation-sensitive material are investigated using UV-Vis spectrophotometry within the dose range 0-100 Gy. Glycerol was used in the hydrogel matrix to promote the dosimetric response and increase the radiation sensitivity. Upon exposing the PAC hydrogel to γ-ray, it exhibits a Surface Plasmon Resonance (SPR) band at 453 nm, and its intensity increases linearly with absorbed doses up to 100 Gy. The results are compared with the silver nitrate gel dosimeter. Glycerol of 15% in the hydrogel matrix enhances the radiation sensitivity by about 30%. PAC hydrogel dosimeter can be considered a near water equivalent material in the 400 keV-20 MeV photon energy range. At doses less than 15 Gy, the PAC hydrogel dosimeter retains higher radiation sensitivity than the gel dosimeter. The total uncertainty (2σ) of the dose estimated using this hydrogel is about 4%. These results may support the validity of using this hydrogel as a dosimeter to verify radiotherapy techniques and dose monitoring during blood irradiation.

Chitosan Schiff bases-based polyelectrolyte complexes with graphene quantum dots and their prospective biomedical applications.

Chitosan (Cs) bis-aldehyde Schiff base derivatives were synthesized by condensation of Cs with three bis-aldehydes namely; butane-1,4-diyl bis(4-formylbenzoate), N,N'-(butane-1,4-diyl)bis(2-(4-formylphenoxy)acetamide) and 4,4'-(butane-1,4-diylbis(oxy))dibenzaldehyde. The prepared Cs derivatives were blended with carboxymethyl chitosan(CMC) and graphene quantum dots (GQDs) to produce semi-IPNs polyelectrolyte complexes (PECs). and characterized with respect to their molecular structure and physio-chemical properties. The antibacterial activity against H. pylori (and in vitro Inosine 5'-monophosphate dehydrogenase IMPDH inhibitory assay) was evaluated. Additionally, a preliminary in vitro assessment for wound healing was performed against PECs in which wound closure percentages, and rates were investigated indicating an accelerated wound healing compared with untreated cells. The PEC based on Schiff base PEC containing amide linkage showed the highest wound healing ability. A minimal inhibitory concentration (MIC) was obtained for the PEC sample containing Cs Schiff base derived from 4,4'-(butane-1, 4-diylbis(oxy))dibenzaldehyde at a dose of 0.98 µg/ml inhibiting H. pylori growth by 100%. Additionally, the selected above-mentioned compound was selected to test its inhibitory activity against the HpIMPDH enzyme in addition to its selectivity towards the hIMPDH2 enzyme and was found to have promising activity against the HpIMPDH enzyme with IC50 value of 0.65 µM, and to be safer and less active against the hIMPDH2 enzyme with IC50 > 10 µM, reflecting its selectivity.

Synthesis, characterization and antimicrobial activity of a novel chitosan Schiff bases based on heterocyclic moieties.

Three heteroaryl pyrazole derivatives; namely 1-phenyl-3-(thiophene-2-yl)-1H-pyrazole-4-carbaldehyde, 1-phenyl-3-(furan-2-yl)-1H-pyrazole-4-carbaldehyde and 1-phenyl-3-(pyridine-3-yl)-1H-pyrazole-4-carbaldehyde were synthesized and reacted with chitosan to form Schiff bases of chitosan. All newly synthesized compounds have been characterized by solubility tests, elemental analysis, spectral (FTIR, 1H NMR) analyses, thermogravimetric analysis and X-ray diffraction (XRD). The Schiff bases were screened for their biological activity against gram-negative bacteria (Escherichia coli and Klebsiella pneumonia), gram-positive bacteria (Staphylococcus aureus and Streptococcus mutans) and fungi (Asperagillus fumigatus and Candida albican). The results indicated that the antimicrobial activity was dependent on the type of the Schiff base moiety. Cytotoxicity of the prepared chitosan derivatives was evaluated by MTT assay and the results indicated the absence of cytotoxic activity.

Comparative evaluation for controlling release of niacin from protein- and cellulose-chitosan based hydrogels.

This work deals with assessing the efficient performance of sodium caseinate (SC) as protein-based drug delivery system of niacin (NA) than carboxymethyl cellulose (CMC). In this respect the hydrogels from complexation of chitosan with sodium caseinate (SC/Ch) or sodium carboxymethyl cellulose (CMC/Ch) were prepared. The Synthesized NA free and loaded hydrogels were characterized by many techniques for examining the interaction, morphology, swelling, encapsulation efficiency (EE) and loading (L) % of niacin, as well as cytotoxicity study. The finding data showed the promising behavior of SC/Ch hydrogel than CMC/Ch hydrogel, toward the amount of loaded NA (95.6%) and in vitro slow sustained release up to 24 h. Whereas, the entrapment efficiency of the CMC/Ch to nicotinic acid was reached 85.6%, and it possessed highly initial burst release followed by a slower release up to 24 h. At pH 7.4 (simulated intestinal fluid) both hydrogels provided higher level of releasing profile to NA than pH 2.1 (gastric fluid). The NA release from hydrogels followed Fickian and non-Fickian diffusion mechanism according to pH 7.4 and 2.1, respectively. It is interesting to note that, the data obtained are higher than those obtained from literature reported hydrogel, e.g., poly (2-hydroxyethyl methacrylate). Neutral red uptake and lactate dehydrogenase assays confirmed both hydrogels have good biocompatibility and could be used as nontoxic drug delivery system. So, we recommended SC/Ch hydrogel as an effective controlled niacin drug delivery system with reducing systemic side effects and improved intestinal targeting efficiency.

Nanocurcumin: preparation, characterization and cytotoxic effects towards human laryngeal cancer cells.

The aim of the present study was to prepare curcumin nanoparticles (nanocurcumin) by a sol-oil method to improve curcumin absorption and bioavailability, and to investigate the therapeutic effects of the prepared nanoparticles on the inhibition mechanisms towards human Hep-2 cancer cells. The nanoparticles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray diffraction, and zeta potential analysis. The prepared curcumin nanoparticles possessed a narrow particle size distribution with an average diameter of 28 nm. The inhibition effects on the growth of human Hep-2 cells were investigated using neutral red uptake and lactate dehydrogenase assays. The results indicated that the nanocurcumin has a selective effect in inhibiting Hep-2 cell growth in a dose- and time-dependent mode with the most effective IC50 value (17 ± 0.31 µg ml-1) obtained after 48 h of incubation without any cytotoxic effects on normal cells. This IC50 value of nanocurcumin revealed a significant increase of early and late apoptotic cells with an intense comet nucleus of Hep-2 cells as a marker of DNA damage. Flow cytometry analysis of the progression of apoptosis in nanocurcumin Hep-2 treated cells showed that arresting in the cell cycle in the G2/M phase with increasing apoptotic cells in the sub-G1 phase. At the same time, real-time PCR analysis indicated that the treatment of Hep-2 cells with nanocurcumin resulted in upregulation of P53, Bax, and Caspase-3, whereas there was downregulation of Bcl-XL. These findings gave insights into understanding that the inhibition mechanisms of nanocurcumin on the proliferation of Hep-2 cancer cells was through the G2/M cell cycle arrest and the induction of apoptosis was dependent on Caspase-3 and p53 activation. However, in vivo studies with an animal model are essential to validate these results.

New wide-stability four-ring azo/ester/Schiff base liquid crystals: synthesis, mesomorphic, photophysical, and DFT approaches.

New four-groups-based azo/ester/Schiff base liquid crystals, ((4-substitutedphenylimino)methyl)phenyl 4-[2-(4-alkoxyhenyl)diazenyl]benzoate, In a-d, were synthesized and analyzed for their mesomorphic stability and optical activity. In these compounds, a terminal alkoxy group of variable chain length from n = 6 to n = 16 carbons is attached to the end of a phenylazo benzoate moiety and the other end of the molecules is connected to a different polar compact substituent X (CH3O, CH3, H, and Cl). FT-IR, 1H NMR, mass spectroscopy and elemental analysis were carried out for molecular structure confirmation of the prepared compounds. The mesomorphic properties were confirmed using a combination of differential scanning calorimetry (DSC) and polarized light microscopy (PLM). The photophysical property was studied by UV-vis spectroscopy. All the prepared homologous series exhibited high thermal stability with a wide-temperature mesomorphic range. The thermal and geometrical parameters of the investigated compounds were estimated by density functional theory (DFT). The results revealed that all the compounds were not completely planar with a relatively high twisting moiety at the CH[double bond, length as m-dash]N part and their twist angles were affected by the electronic nature of the attached X group. Moreover, the calculated quantum chemical parameters as determined by the DFT approach of the investigated compounds were related to the experimentally determined values of the mesophase thermal stability (T c) and mesophase temperature ranges (ΔT SmA and ΔT N) as well as the type of the mesophase.

Encapsulation of ciprofloxacin within modified xanthan gum- chitosan based hydrogel for drug delivery.

The aim of the present work was to investigate the preparation of polyelectrolyte hydrogel as potential drug carrier for antibacterial Ciprofloxacin drug (CFX), intended for controlled release formulation. Hydrogel of N-trimehtyl chitosan (TMC)/sodium carboxymethyl xanthan gum (CMXG) was prepared and ciprofloxacin was employed as a model drug to investigate the loading and release performance of the prepared hydrogel. FTIR, DSC, TGA and SEM analysis were used to characterize the TMC/CMXG hydrogel and its CFX loaded hydrogel. The results showed that the ciprofloxacin was successfully incorporated and released from the prepared hydrogel without the loss of structural integrity or the change in its functionality. The encapsulation efficiency of CFX within the prepared hydrogel was found to be increased with increasing the concentration of drug reaching about 93.8 ±â€¯2.1% with concentration of CFX 250 µg/ml. It was shown also that the drug is entrapped within the gel without significant interaction as confirmed from FTIR spectra and DSC analysis. In vitro release study in phosphate buffer saline (PBS), indicated the steady rise in cumulative drug release with the highest release amount, reaching about 96.1 ±â€¯1.8% up to 150 min, whereby the gel with high drug loading efficiency (3.52 ±â€¯0.07%) displayed faster and higher release rate than that of gel containing a smaller amount of drug (0.44 ±â€¯0.01%). The release kinetics of loaded drug followed zero-order kinetics. CFX drug loaded hydrogel showed high activity against the gram positive and gram negative bacterial strains due to the successful released of CFX from the CFX loaded hydrogel into the tested bacterial strains with the highest diameter of inhibition zone against Escherichia coli (67.0 ±â€¯1.0) as compared to reference antibiotic, Gentamicin (28 ±â€¯0.5). Cytotoxicity of the prepared hydrogel was examined in vitro using lung human normal cell lines and showed the highest cell viability (97 ±â€¯0.5%) at concentration up to 50 µg/ml. Consequently, TMC/CMXG hydrogel can be proposed as new controlled release drug delivery system.

Synthesis, characterization and antimicrobial activity of biguanidinylated chitosan-g-poly[(R)-3-hydroxybutyrate].

Chitosan biguanidine hydrochloride (ChG) and low molecular weight poly[(R)-3-hydroxybutyrate] (PHB) were successfully prepared to overcome the solubility problem of chitosan and PHB and also to enhance antimicrobial activity of chitosan. The graft copolymers based on ChG and PHB (ChG-grafted PHB) were then prepared via condensation reaction of the carboxylic groups of PHB with the amino groups of ChG. These graft copolymers swell in water. The prepared graft copolymers were characterized by FTIR, 1H NMR, X-ray diffraction (XRD) and thermal analyses (TGA and DSC). TGA and DSC results revealed that the thermal stability and crystallinity of the graft copolymers were found to increase as the content of PHB increased. The antimicrobial activity of both ChG and ChG-grafted PHB, against Streptococcus pneumoniae, Bacillus subtilis, Escherichia coli (as examples of bacteria) and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum (as examples of fungi), were tested. Among them, ChG and ChG-grafted PHB with the highest grafting percent investigated showed to possess relatively higher antimicrobial activity with low MIC values in the range of 0.49-3.90µgmL-1.

Synthesis, characterization, and biological activity of cross-linked chitosan biguanidine loaded with silver nanoparticles.

Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, 1H NMR and 13C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine. The obtained nanoparticles were uniform and spherical with average size of 9.6 ± 0.5 nm. The prepared CChG/AgNPs composites were characterized for their morphology, thermal properties, cytotoxicity and antimicrobial activity. The SEM images showed that the AgNPs are well imbedded in the CChG matrix. The thermal stability of CChG was improved with incorporation of AgNPs. The CChG and CChG/AgNPs showed less cytotoxicity to breast cancer cells (MCF-7). Compared with chitosan and CChG, the ChG and CChG/AgNPs showed better antimicrobial activity against Streptococcus pneumoniae and Bacillus subtilis as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum as fungi.

Isolation and characterization of chitosan from different local insects in Egypt.

Chitin was extracted from four different local sources: the shrimp (Penaeus monodon), the desert locust (Schistocerca gregaria), the honey bee (Apis mellifera) and the beetles (Calosoma rugosa). Chitosan was then obtained by deacetylation of chitin and physicochemically characterized using the Fourier transform infrared (FTIR) and X-ray diffraction. The moisture content, water binding capacity, fats binding capacity, ash content were determined and chitosans morphology was visualized using the scanning electron microscope (SEM). The difference between the obtained chitosans from three insect sources and α-chitosan from shrimp in terms of crystallinity, fibrous structure was discussed.

Synthesis, characterization and biological activity of Schiff bases based on chitosan and arylpyrazole moiety.

The Schiff bases of chitosan were synthesized by the reaction of chitosan with 3-(4-substituted-phenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde. The structure of the prepared chitosan derivatives was characterized by FT-IR spectroscopy, elemental analysis, and X-ray diffraction studies and thermogravimetric analysis (TG). The results show that the specific properties of Schiff bases of chitosan can be altered by modifying the molecular structures with proper substituent groups.TG results reveal that the thermal stability of the prepared chitosan Schiff bases was lower than chitosan. The activation energy of decomposition was calculated using Coats-Redfern model. The antimicrobial activity of chitosan and Schiff bases of chitosan were investigated against Streptococcus pneumonia, Bacillis subtilis, Escherichia coli (as examples of bacteria) and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum (as examples of fungi). The results indicated that the antimicrobial activity of the Schiff bases was stronger than that of chitosan and was dependent on the substituent group. The activity of un-substituted arylpyrazole chitosan derivative toward the investigated bacteria and fungi species was better than the other derivatives.