Displaying publications 41 - 54 of 54 in total

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  1. Preparation of magnetic, macro-reticulated cross-linked chitosan for tetracycline removal from aquatic systems
    Oladoja NA, Adelagun RO, Ahmad AL, Unuabonah EI, Bello HA
    Colloids Surf B Biointerfaces, 2014 May 1;117:51-9.
    PMID: 24632030 DOI: 10.1016/j.colsurfb.2014.02.006
    A novel adsorbent, magnetic, macro-reticulated cross-linked chitosan (MRC) was synthesised for the removal of tetracycline (TC) from water using a source of biogenic waste (gastropod shells) as a pore-forming agent. The insertion of crosslinks into the chitosan frame was confirmed by FTIR analysis, while the stability of the MRC was demonstrated via a stability test performed in an acidic solution. The enhanced porosity of the MRC was confirmed by the evaluation of its porosity, a swelling test and the determination of its specific surface area. The time-concentration profile of the sorption of TC onto the MRC demonstrated that equilibrium was attained relatively quickly (120 min), and the data obtained fitted a pseudo second order (r(2)>0.99) kinetic equation better than a pseudo first order or reversible first order kinetic equation. The optimisation of process variables indicated that the sorption of TC onto the MRC was favoured at a low solution pH and that the presence of organics (simulated by the addition of humic acid) negatively impacted the magnitude of TC removal. The area of coverage of TC on the MRC (2.51 m(2)/g) was low compared to the specific surface area of the MRC (47.95 m(2)/g). The value of the calculated energy of adsorption of TC onto the MRC was 100 kJ/mol, which is far above the range of 1-16 kJ/mol stipulated for physical adsorption.
    Matched MeSH terms: Cross-Linking Reagents/chemistry*
  2. Fulltext QuadraPure-supported palladium nanocatalysts for microwave-promoted Suzuki cross-coupling reaction under aerobic condition
    Liew KH, Loh PL, Juan JC, Yarmo MA, Yusop RM
    ScientificWorldJournal, 2014;2014:796196.
    PMID: 25054185 DOI: 10.1155/2014/796196
    Cross-linked resin-captured palladium (XL-QPPd) was readily prepared by simple physical adsorption onto the high loading QuadraPure macroporous resin and a subsequent reduction process. To enhance the mechanical stability, entrapped palladium nanocatalysts were cross-linked with succinyl chloride. Both transmission electron microscopy images and X-ray diffraction analysis revealed that the palladium nanoparticles were well dispersed with diameters ranging in 4-10 nm. The catalyst performed good catalytic activity in microwave-promoted Suzuki cross-coupling reactions in water under aerobic condition with mild condition by using various aryl halides and phenylboronic acid. In addition, the catalyst showed an excellent recyclability without significant loss of catalytic activity.
    Matched MeSH terms: Cross-Linking Reagents/chemistry
  3. Fulltext Removal of parabens from aqueous solution using β-cyclodextrin cross-linked polymer
    Chin YP, Mohamad S, Abas MR
    Int J Mol Sci, 2010 Sep 20;11(9):3459-71.
    PMID: 20957106 DOI: 10.3390/ijms11092459
    The removal of four parabens, methyl-, ethyl-, propyl-, and benzyl-paraben, by β-cyclodextrin (β-CD) polymer from aqueous solution was studied. Different β-CD polymers were prepared by using two cross-linkers, i.e., hexamethylene diisocyanate (HMDI) and toluene-2,6-diisocyanate (TDI), with various molar ratios of cross-linker. β-CD-HMDI polymer with molar ratio of 1:7 and β-CD-TDI polymer with ratio 1:4 gave the highest adsorption of parabens among the β-CD-HMDI and β-CD-TDI series, and were subsequently used for further studies. The adsorption capacity of β-CD-HMDI is 0.0305, 0.0376, 0.1854 and 0.3026 mmol/g for methyl-, ethyl-, propyl-, and benzyl-paraben, respectively. β-CD-TDI have higher adsorption capacities compared with β-CD-HMDI, the adsorption capacity are 0.1019, 0.1286, 0.2551, and 0.3699 mmol/g methyl-, ethyl-, propyl-, and benzyl-paraben respectively. The parameters studied were adsorption capacity, water retention, and reusability. Role of both cross-linker in adsorption, hydrophobicity of polymers, and adsorption capacity of different parabens were compared and discussed. All experiments were conducted in batch adsorption technique. These polymers were applied to real samples and showed positive results.
    Matched MeSH terms: Cross-Linking Reagents/chemistry*
  4. Renal denervation restores the baroreflex control of renal sympathetic nerve activity and heart rate in Wistar-Kyoto rats with cisplatin-induced renal failure
    Khan SA, Sattar MA, Rathore HA, Abdulla MH, Ud Din Ahmad F, Ahmad A, et al.
    Acta Physiol (Oxf), 2014 Mar;210(3):690-700.
    PMID: 24438102 DOI: 10.1111/apha.12237
    There is evidence that in chronic renal failure, the sympathetic nervous system is activated. This study investigated the role of the renal innervation in suppressing high- and low-pressure baroreflex control of renal sympathetic nerve activity and heart rate in cisplatin-induced renal failure.
    Matched MeSH terms: Cross-Linking Reagents/toxicity
  5. Robust cross-linked cyclodextrin glucanotransferase from Bacillus lehensis G1 aggregates using an improved cross-linker and a new co-aggregant for the production of cyclodextrins
    Jailani N, Jaafar NR, Rahman RA, Illias RM
    Enzyme Microb Technol, 2023 Sep;169:110283.
    PMID: 37433237 DOI: 10.1016/j.enzmictec.2023.110283
    One of the potentials of carrier-free cross-linked enzyme aggregates (CLEA) immobilization is the ability to be separated and reuse. Yet, it might be impeded by the poor mechanical stability resulting low recyclability. CLEA of CGTase from Bacillus lehensis G1 (CGTase G1-CLEA) using chitosan (CS) as a cross-linker demonstrated high activity recovery however, displayed poor reusability. Therefore, the relationship between mechanical strength and reusability is studied by enhancing the CS mechanical properties and applying a new co-aggregation approach. Herein, CS was chemically cross-linked with glutaraldehyde (GA) and GA was introduced as a co-aggregant (coGA). CGTase G1-CLEA developed using an improved synthesized chitosan-glutaraldehyde (CSGA) cross-linker and a new coGA technique showed to increase its mechanical stability which retained 63.4% and 52.2%, respectively compared to using CS that remained 33.1% of their initial activity after stirred at 500 rpm. The addition of GA impacted the morphology and interaction consequently stabilizing the CLEAs durability in production of cyclodextrins. As a result, the reusability of CGTase G1-CLEA with CSGA and coGA increased by 56.6% and 42.8%, respectively compared to previous CLEA after 5 cycles for 2 h of reaction. This verifies that the mechanical strength of immobilized enzyme influences the improvement of its operational stability.
    Matched MeSH terms: Cross-Linking Reagents/chemistry
  6. Salmon skin gelatin-corn zein composite films produced via crosslinking with glutaraldehyde: Optimization using response surface methodology and characterization
    Fan HY, Duquette D, Dumont MJ, Simpson BK
    Int J Biol Macromol, 2018 Dec;120(Pt A):263-273.
    PMID: 30130612 DOI: 10.1016/j.ijbiomac.2018.08.084
    Composite films comprised of salmon (Salmo salar) skin gelatin and zein were prepared via crosslinking with glutaraldehyde. Response surface methodology (RSM) was used to optimize film composition to maximize tensile strength (TS) and elongation at break (EAB), and to minimize water solubility (WS) of the films. The significant (P 
    Matched MeSH terms: Cross-Linking Reagents/chemistry*
  7. Swelling behaviour and controlled drug release from cross-linked κ-carrageenan/NaCMC hydrogel by diffusion mechanism
    Hezaveh H, Muhamad II, Noshadi I, Shu Fen L, Ngadi N
    J Microencapsul, 2012;29(4):368-79.
    PMID: 22309480 DOI: 10.3109/02652048.2011.651501
    We studied a model system of controlled drug release using beta-carotene and κ-carrageenan/NaCMC hydrogel as a drug and a device, respectively. Different concentrations of genipin were added to crosslink the beta-carotene loaded beads by using the dripping method. Results have shown that the cross-linked beads possess lower swelling ability in all pH conditions (pH 1.2 and 7.4), and swelling ratio decreases with increasing genipin concentration. Microstructure study shows that cross-linking has enhanced the stability and structure of the beads network. Determination of diffusion coefficient for the release of encapsulated beta-carotene indicates less diffusivity when beads are cross-linked. Swelling models using adaptive neuro fuzzy show that using genipin as a cross-linker in the kC/NaCMC hydrogels affects the transport mechanism. The model shows very good agreement with the experimental data that indicates that applying ANFIS modelling is an accurate, rapid and simple way to model in such a case for controlled release applications.
    Matched MeSH terms: Cross-Linking Reagents
  8. Synthesis and functionalization of chitosan built hydrogel with induced hydrophilicity for extended release of sparingly soluble drugs
    Ullah F, Javed F, Othman MBH, Khan A, Gul R, Ahmad Z, et al.
    J Biomater Sci Polym Ed, 2018 03;29(4):376-396.
    PMID: 29285989 DOI: 10.1080/09205063.2017.1421347
    Addressing the functional biomaterials as next-generation therapeutics, chitosan and alginic acid were copolymerized in the form of chemically crosslinked interpenetrating networks (IPNs). The native hydrogel was functionalized via carbodiimide (EDC), catalyzed coupling of soft ligand (1,2-Ethylenediamine) and hard ligand (4-aminophenol) to replace -OH groups in alginic acid units for extended hydrogel- interfaces with the aqueous and sparingly soluble drug solutions. The chemical structure, Lower solution critical temperature (LCST ≈ 37.88 °C), particle size (Zh,app ≈ 150-200 nm), grain size (160-360 nm), surface roughness (85-250 nm), conductivity (37-74 mv) and zeta potential (16-32 mv) of native and functionalized hydrogel were investigated by using FT-IR, solid state-13C-NMR, TGA, DSC, FESEM, AFM and dynamic light scattering (DLS) measurements. The effective swelling, drug loading (47-78%) and drug release (53-86%) profiles were adjusted based on selective functionalization of hydrophobic IPNs due to electrostatic complexation and extended interactions of hydrophilic ligands with the aqueous and drug solutions. Drug release from the hydrogel matrices with diffusion coefficient n ≈ 0.7 was established by Non- Fickian diffusion mechanism. In vitro degradation trials of the hydrogel with a 20% loss of wet mass in simulated gastric fluid (SGF) and 38% loss of wet mass in simulated intestinal fluid (SIF), were investigated for 400 h through bulk erosion. Consequently, a slower rate of drug loading and release was observed for native hydrogel, due to stronger H-bonding, interlocking and entanglement within the IPNs, which was finely tuned and extended by the induced hydrophilic and functional ligands. In the light of induced hydrophilicity, such functional hydrogel could be highly attractive for extended release of sparingly soluble drugs.
    Matched MeSH terms: Cross-Linking Reagents/chemistry
  9. Fulltext The Effect of Cross-linking Efficiency of Drug-Loaded Novel Freeze Gelated Chitosan Templates for Periodontal Tissue Regeneration
    Qasim SSB, Nogueria LP, Fawzy AS, Daood U
    AAPS PharmSciTech, 2020 Jun 16;21(5):173.
    PMID: 32548717 DOI: 10.1208/s12249-020-01708-x
    Innovative strategies for periodontal regeneration have been the focus of research clusters across the globe for decades. In order to overcome the drawbacks of currently available options, investigators have suggested a novel concept of functionally graded membrane (FGM) templates with different structural and morphological gradients. Chitosan (CH) has been used in the past for similar purpose. However, the composite formulation of composite and tetracycline when cross-linked with glutaraldehyde have received little attention. Therefore, the purpose of the study was to investigate the drug loading and release characteristics of novel freeze gelated chitosan templates at different percentages of glutaraldehyde. These were cross-linked with 0.1 and 1% glutaraldehyde and loaded with doxycycline hyclate. The electron micrographs depicted porous morphology of neat templates. After cross-linking, these templates showed compressed ultrastructures. Computerized tomography analysis showed that the templates had 88 to 92% porosity with average pore diameter decreased from 78 to 44.9 μm with increasing concentration. Fourier transform infrared spectroscopy showed alterations in the glycosidic segment of chitosan fingerprint region which after drug loading showed a dominant doxycycline spectral composite profile. Interestingly, swelling profile was not affected by cross-linking either at 0.1 and 1% glutaraldehyde and template showed a swelling ratio of 80%, which gained equilibrium after 15 min. The drug release pattern also showed a 40 μg/mL of release after 24 h. These doxycycline-loaded templates show their tendency to be used in a functionally graded membrane facing the defect site.
    Matched MeSH terms: Cross-Linking Reagents/pharmacokinetics; Cross-Linking Reagents/chemistry*
  10. The effect of nanoparticles on gastrointestinal release from modified κ-carrageenan nanocomposite hydrogels
    Hezaveh H, Muhamad II
    Carbohydr Polym, 2012 Jun 5;89(1):138-45.
    PMID: 24750615 DOI: 10.1016/j.carbpol.2012.02.062
    In this article, silver and magnetite nanofillers were synthesized in modified κ-carrageenan hydrogels using the in situ method. The effect of metallic nanoparticles in gastro-intestinal tract (GIT) release of a model drug (methylene blue) has been investigated. The effect of nanoparticles loading and genipin cross-linking on GIT release of nanocomposite is also studied to finally provide the most suitable drug carrier system. In vitro release studies revealed that using metallic nanocomposites hydrogels in GIT studies can improve the drug release in intestine and minimize it in the stomach. It was found that cross-linking and nanofiller loading can significantly improve the targeted release. Therefore, applying metallic nanoparticles seems to be a promising strategy to develop GIT controlled drug delivery.
    Matched MeSH terms: Cross-Linking Reagents/chemistry
  11. Tumor regression and modulation of gene expression via tumor-targeted tocotrienol niosomes
    Tan DM, Fu JY, Wong FS, Er HM, Chen YS, Nesaretnam K
    Nanomedicine (Lond), 2017 Oct;12(20):2487-2502.
    PMID: 28972460 DOI: 10.2217/nnm-2017-0182
    AIM: To develop 6-O-palmitoyl-ascorbic acid-based niosomes targeted to transferrin receptor for intravenous administration of tocotrienols (T3) in breast cancer.

    MATERIALS & METHODS: Niosomes were prepared using film hydration and ultrasonication methods. Transferrin was coupled to the surface of niosomes via chemical linker. Nanovesicles were characterized for size, zeta potential, morphology, stability and biological efficacy.

    RESULTS: When evaluated in MDA-MB-231 cells, entrapment of T3 in niosomes caused 1.5-fold reduction in IC50 value compared with nonformulated T3. In vivo, the average tumor volume of mice treated with tumor-targeted niosomes was 12-fold lower than that of untreated group, accompanied by marked downregulation of three genes involved in metastasis.

    CONCLUSION: Findings suggested that tumor-targeted niosomes served as promising delivery system for T3 in cancer therapy.

    Matched MeSH terms: Cross-Linking Reagents
  12. Tunable Schiff's base-cross-linked chitosan composite for the removal of reactive red 120 dye: Adsorption and mechanism study
    Jawad AH, Mubarak NSA, Abdulhameed AS
    Int J Biol Macromol, 2020 Jan 01;142:732-741.
    PMID: 31760013 DOI: 10.1016/j.ijbiomac.2019.10.014
    In this study, tunable Schiff's base-cross-linked chitosan-glutaraldehyde (CS-GLA) was modified and applied to remove reactive red 120 (RR120) dye from an aqueous solution. Different ratios of TiO2 nanoparticles, such as 25% TiO2 nanoparticles (CS-GLA/TNC-25) and 50% TiO2 nanoparticles (CS-GLA/TNC-50), were loaded into the CS-GLA's molecular structure. The adsorptive properties of CS-GLA, CS-GLA/TNC-25, and CS-GLA/TNC-50 for the RR120 dye in the aqueous solution were evaluated. CS-GLA/TNC-25 exhibited the best adsorptive property possibly because of the perfect balancing between the surface area and available amine (NH2) groups in the composite formulation. The impact of adsorption key parameters, such as adsorbent dosage (0.01-1.2 g), RR120 dye concentration (30-400 mg/L), solution pH (3-12), and contact time (0-400 min) were explored by batch adsorption mode. The adsorption was well described by the Freundlich model and pseudo-second order kinetic model. The adsorption capacity of CS-GLA/TNC-25 for RR120 dye was 103.1 mg/g at 303K. The adsorption mechanism of RR120 on the CS-GLA/TNC-25 surface can be assigned to various interactions, such as electrostatic attraction, n-π stacking, and H-bonding. Results indicate the potential application of CS-GLA/TNC-25 as environment-friendly biosorbent for removing acid and/or textile dyes, such as RR120, from aqueous environments.
    Matched MeSH terms: Cross-Linking Reagents/chemistry*
  13. Using response surface methodology to optimize process parameters and cross-linking agents for production of combined-cross-linked bovine serum albumin gels
    Gan CY, Alkarkhi AF, Easa AM
    J Biosci Bioeng, 2009 Apr;107(4):366-72.
    PMID: 19332294 DOI: 10.1016/j.jbiosc.2008.12.007
    D-optimal design was employed to optimize the mixture of cross-linking agents formulation: microbial transglutaminase (MTGase) and ribose, and the processing parameters (i.e. incubation and heating time) in the mixture in order to obtain combined-cross-linked bovine serum albumin gels that have high gel strength, pH close to neutral and yet medium in browning. Analysis of variance (ANOVA) showed that the contribution of quadratic term to the model over the linear was significant for pH and L* value, whereas linear model was significant for gel strength. Optimization study using response surface methodology (RSM) was performed to the mixture components and process variables and the optimum conditions obtained were: MTGase of 1.34-1.43 g/100 mL, ribose of 1.07-1.16 g/100 mL, incubation time of 5 h at 40 degrees C and heating time of 3 h at 90 degrees C.
    Matched MeSH terms: Cross-Linking Reagents/chemistry*
  14. Water activity effect on lipase immobilized onto different compositions of poly(HEMA-MMA)
    Esa NM, Yunus WM, Ahmad MB, Basri M, Razak CN, Salleh AB
    Ann N Y Acad Sci, 1998 Dec 13;864:489-92.
    PMID: 9928130
    Matched MeSH terms: Cross-Linking Reagents
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