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For chemical modification, p-aminobenzoic acid was incorporated into chitosan Schiff base (ACsSB) and chitosan (ACs). Two ACs-based CuO nanoparticles composites; ACs/CuONPs-1 % and ACs/CuONPs-5 %, were also synthesized. Their structures were emphasized utilizing several analytical techniques; elemental analysis, FTIR, 1 H NMR, XRD, SEM, EDX and TEM. Compared with standard cyclooxygenase (COX) inhibitor, Celecoxib, the prepared biomaterials showed in vitro selective inhibitory effectiveness against COX-2 enzyme that could be sorted, according to their MIC values that produce 50 % inhibition of COX-2 enzyme activity, as follows: Celecoxib (0.28 μg/mL) > ACs/CuONPs-5 % (4.1 μg/mL) > ACs/CuONPs-1 % (14.8 μg/mL) > ACs (38.5 μg/mL) > ACsSB (58.9 μg/mL) > chitosan (>125 μg/mL). Further, ACs/CuONPs-5 % has more in vitro inhibition efficiency towards Helicobacter pylori (H. pylori) than the other prepared biomaterials. Interestingly, the MIC value of 100 % growth inhibition of H. pylori for ACs/CuONP-5 % is equal to that of drug Clarithromycin (1.95 μg/mL). Thus, ACs/CuONPs-5 % has a promising potential as anti-H. pylori and selective anti-inflammatory agent. ACs/CuONPs-5 % is safe on the human gastric normal cells (GES-1). Therefore, amalgamation of both p-aminobenzoic acid and CuONPs into chitosan extremely promoted its anti-inflammatory and anti-H. pylori activity. This is a promising approach to achieve methods successful to compete the conventional antibiotics., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Two novel chemically cross-linked chitosan hydrogels were successfully prepared via insertion of oxalyl dihydrazide moieties between chitosan Schiff's base chains (OCsSB) and between chitosan chains (OCs). For more modification, two different concentrations of ZnO nanoparticles (ZnONPs) were loaded into OCs to obtain OCs/ZnONPs-1 % and OCs/ZnONPs-3 % composites. The prepared samples were recognized using elemental analyses, FTIR, XRD, SEM, EDS and TEM. Their inhibitory action against microbes and biofilms were classified as: OCs/ZnONPs-3 % > OCs/ZnONPs-1 % > OCs > OCsSB > chitosan. OCs has inhibition activity similar to Vancomycin of minimum inhibitory concentration (MIC) value of 3.9 μg/mL against P. aeruginosa. OCs exhibited minimum biofilm inhibitory concentration (MBIC) values (from 31.25 to 62.5 μg/mL) less than that of OCsSB (from 62.5 to 250 μg/mL) which lower than that of chitosan (from 500 to 1000 μg/mL) against S. epidermidis, P. aeruginosa and C. albicans. OCs/ZnNPs-3 % showed MIC value (that caused 100 % inhibition of Clostridioides difficile, C. difficile) of 0.48 μg/mL much lower than Vancomycin (1.95 μg/mL). Both OCs and OCs/ZnONPs-3 % composite were safe on normal human cells. Thus, inclusion of oxalyl dihydrazide and ZnONPs into chitosan greatly reinforced its antimicrobial activity. This is a good strategy to accomplish adequate systems for competing traditional antibiotics., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Two novel chitosan derivatives were prepared by incorporating salicylhydrazide into chitosan Schiff base (SCsSB) and chitosan (SCs). Two nanocomposites, SCs/TiO 2 -1% and SCs/TiO 2 -3%, were also prepared. Their structures were confirmed using elemental analyses, FTIR, XRD, SEM, EDX and TEM. Their antimicrobial and anti-biofilm activities were arranged as: SCs/TiO 2 -3% > SCs/TiO 2 -1% > SCs > SCsSB > chitosan. SCs showed minimum inhibitory concentration (MIC) value of 1.95 μg/mL against A. niger which was comparable with that of Amphotericin B. SCs/TiO 2 -3% showed higher inhibition against S. epidermidis, S. aureus, S. pyogenes, P. aeruginosa and E. coli than Vancomycin. While, it showed comparable inhibition activity to that of Vancomycin against B. subtilis and P. mirabilis. SCs/TiO 2 -3% showed MIC values equal 0.48 and 0.98 μg/mL corresponded to 0.98 and 1.95 μg/mL of Amphotericin B against C. albicans, A. fumigatus and A. niger, respectively. SCs/TiO 2 -3% showed much lower minimum biofilm inhibitory concentration (MBIC) values, ranged between 1.95 and 7.81 μg/mL, than those of SCs, ranged from 62.5 to 125 μg/mL. SCs/TiO 2 -3% was safe on normal human cells. The modifiers and TiO 2 nanoparticles incorporated into chitosan in one structure developed its performance. It is approach for attaining appropriate structures which are good competitors for antimicrobial agents., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Chitosan (Cs) was cross-linked with four various quantities of 4,4'-(5,5'‑carbonylbis(1,3-dioxoisoindoline-5,2-diyl))dibenzoyl isothiocyanate. Elemental analysis, FTIR and 1 H NMR spectroscopy assured that the amino groups of chitosan reacted with the isothiocyanate groups of the cross-linker producing four new hydrogels namely as BBTU-Cs-1, BBTU-Cs-2, BBTU-Cs-3, and BBTU-Cs-4 according to the increment of their cross-linking content, respectively. SEM showed their porous structures and XRD indicated their amorphous nature. Their swell ability increased with decreasing the medium pH value and with increasing cross-linking density. In comparison with the popular COX inhibitor Celecoxib, these hydrogels showed an inhibition activity towards COX enzymes with selective inhibition towards COX-2. Their inhibition activity could be arranged as follows: Celecoxib > BBTU-Cs-4 > BBTU-Cs-3 > BBTU-Cs-2 > BBTU-Cs-1. BBTU-CS-4 hydrogel exhibited a potent inhibition against COX-2 (IC 50 0.42 μg/ml) compared with that observed for the standard Celecoxib (IC 50 0.26 μg/ml). BBTU-Cs-4 is more potent against H. pylori compared to the other hydrogels. BBTU-Cs-4 at a concentration of 7.81 μg/ml is able to kill 100% of the H. pylori and exhibits a preferential ability to inhibit 89.35% of COX-2 than COX-1 (0%). These findings make BBTU-Cs-4 a promising anti-H. pylori and selective anti-inflammatory agent., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Novel antimicrobial copolymers resulted from free radical copolymerization of gelatinized corn starch in aqueous solution with different amounts of 4-acrylamidobenzoic acid monomer using ammonium persulfate (APS)/sodium bisulfite (NaHSO 3 ) as a redox initiator. The grafting copolymerization was evidenced by FTIR, 1 HNMR, scanning electron microscopy (SEM) and X-ray diffraction. The thermal stability was improved after the grafting reaction as detected from IPDT values calculated from the thermogravimetric analysis. The effect of changing grafting parameters (initiator concentration, monomer concentration, reaction time and temperature) on graft copolymerization were studied by measuring the grafting percentage (%G), grafting efficiency (%GE) and homopolymer percentage (%H). The optimum grafting conditions were determined as follows: Initiator concentration [I] = 3 × 10 -2  mol/L, monomer concentration [M] = 0.25 mol/L, reaction temperature = 65 °C and reaction time = 2 h. The prepared copolymers exhibited swelling ability in both water and 0.9% saline solution. The antimicrobial study revealed a high degree of inhibition against different strains of Gram-positive bacteria, Gram-negative bacteria and fungi when compared with neat starch., (Copyright © 2019. Published by Elsevier B.V.)

Four chemically modified chitosan derivatives 1-4 were designed and synthesized via a series of four reactions; first by reaction with benzaldehyde to protect its amino groups (Derivative 1), second by reaction with epichlorohydrine (Derivative 2), third by reaction with aminobenzhydrazide (Derivative 3), and forth by removing of benzaldehyde to restore the free amino groups on the chitosan (Derivative 4). Two multi-walled carbon nanotube (MWCNT) biocomposites based on Derivative 4 were also prepared. The structure of the prepared derivatives and MWCNT composites was elucidated using elemental analyses, FTIR, XRD, SEM and TEM. The modified chitosan derivatives and MWCNT composites showed better antimicrobial activities than that of chitosan against Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Aspergillus niger, Cryptococcus neoformans and Candida tropicalis as judged by their higher inhibition zone diameters using the agar well diffusion technique. These derivatives and MWCNT composites are more potent against Gram-positive bacteria than against Gram-negative bacteria. The MWCNT composites displayed comparable or even better antimicrobial activities than the reference bactericides or fungicides. Thus, structural modification of chitosan through combination with functionalized moieties and MWCNTs in one system was taken as a way to achieve promising templates for antimicrobial agents and to be appropriate candidates for medical applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study demonstrated that antibacterial cellulosic textiles can be fabricated in eco-friendly manner by grafting of monochlorotriazinyl β-cyclodextin (MCT-βCD) onto knitted and woven cotton fabrics followed by post-loading of any of the green active ingredients namely Rosemary oil, Lavender oil, Clove oil, Cinnamon oil, Aloe vera gel, Vanillin, Ag-ions, Natural Yellow 7 and Natural Red 25 dyes into the hydrophobic cavities of grafted β-CD moieties. Some of the grafted, post-loaded fabric samples were characterized by FTIR, SEM, and EDS analysis. The enhancement in the imparted antibacterial functionality as well as durability to wash are governed by type of cellulosic substrate, kind, chemistry, antibacterial activity as well as extent of inclusion and subsequent release of the hosted bioactive agent. The obtained results revealed that the antibacterial efficacy follows the deceasing orders: i) knitted fabric > woven fabric and ii) Ag-ions > Lavender oil > Natural Yellow 7 > Aloe vera > Cinnamon oil > Natural Red 25 > Vanillin > Clove oil > Rosemary oil-loaded fabric sample, keeping other parameters constant., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this work, chitosan (CS) was cross-linked with different amounts of pyromellitimide benzoyl thiourea moieties. The structure of the cross-linked CS was confirmed by elemental analyses, FTIR and (1)H- NMR spectroscopy. The cross-linking process proceeds via reacting of the amino groups of CS with the isothiocyanate groups of the N,N'-bis [4-(isothiocyanate carbonyl)phenyl] pyromellitimide cross-linker. The amount of the cross-linker was varied with respect to CS to produce four new pyromellitimide benzoyl thiourea cross-linked CS (PIBTU-CS) hydrogels designated as PIBTU-CS-1, PIBTU-CS-2, PIBTU-CS-3, and PIBTU-CS-4 of increasing cross-linking degree percent of 11, 22, 44 and 88%, respectively. The scanning electron microscopy observation indicates the extremely porous structure of the hydrogels. XRD results showed that the crystallinity of CS was decreased upon cross-linking. The four hydrogels exhibit a higher antibacterial activity on Bacillus subtilis and Streptococcus pneumoniae as Gram positive bacteria and against Escherichia coli as Gram negative bacteria and higher antifungal activity on Aspergillus fumigatus, Syncephalastrum racemosum and Geotricum candidum than that of the parent CS as shown from their higher inhibition zone diameters and their lower MIC values. The swell ability of the hydrogel as well as their antimicrobial activity increased with increasing cross-linking density., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Acetyl, chloroacetyl and benzoyl thiourea derivatives of carboxymethyl chitosan (ATUCMCS, CATUCMCS, and BZTUCMCS) with comparable grafting degree were synthesized and their structures were characterized by FTIR spectroscopy and elemental analyses. The antimicrobial behaviors of CMCS and its derivatives against three types of bacteria [Bacillis subtilis (B. subtilis), Staphylococous aureus (S. aureus) and Escherichia coli (E. coli)] and three crop-threatening pathogenic fungi [Aspergillus fumigate (A. fumigate), Geotrichum candidum (G. candidum) and Candida albicans (C. albicans)] were investigated. The results indicated that the antibacterial and the antifungal activities of the acyl thiourea derivatives are much higher than that of the parent CMCS. The acyl thiourea derivatives were more potent in case of Gram-positive bacteria than Gram-negative bacteria. This is illustrated for example by the values of minimum inhibitory concentration (MIC) of the ATUCMCS, CATUCMCS and BZTUCMCS against B. subtilis were 3.9, 15.6 and 62.5, respectively, while the MIC values of these derivatives against E. coli were 62.5, 125 and 500. Moreover, the antifungal activity of the CATUCMCS is higher than that of the acetyl and benzoyl thiourea derivatives. This may be due to the presence of chlorine atom., (Copyright © 2012 Elsevier B.V. All rights reserved.)