Displaying publications 1 - 20 of 242 in total

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  1. Development and physical characterization of polymer-fish oil bigel (hydrogel/oleogel) system as a transdermal drug delivery vehicle
    Rehman K, Mohd Amin MC, Zulfakar MH
    J Oleo Sci, 2014;63(10):961-70.
    PMID: 25252741
    Polymer-Fish oil bigel (hydrogel/oleogel colloidal mixture) was developed by using fish oil and natural (sodium alginate) and synthetic (hydroxypropyl methylcellulose) polymer for pharmaceutical purposes. The bigels were closely monitored and thermal, rheological and mechanical properties were compared with the conventional hydrogels for their potential use as an effective transdermal drug delivery vehicle. Stability of the fish oil fatty acids (especially eicosapentanoic acid, EPA and docosahexanoic acid, DHA) was determined by gas chromatography and the drug content (imiquimod) was assessed with liquid chromatography. Furthermore, in vitro permeation study was conducted to determine the capability of the fish oil-bigels as transdermal drug delivery vehicle. The bigels showed pseudoplastic rheological features, with excellent mechanical properties (adhesiveness, peak stress and hardness), which indicated their excellent spreadability for application on the skin. Bigels prepared with mixture of sodium alginate and fish oil (SB1 and SB2), and the bigels prepared with the mixture of hydroxypropyl methylcellulose and fish oil (HB1-HB3) showed high cumulative permeation and drug flux compared to hydrogels. Addition of fish oil proved to be beneficial in increasing the drug permeation and the results were statistically significant (p < 0.05, one-way Anova, SPSS 20.0). Thus, it can be concluded that bigel formulations could be used as an effective topical and transdermal drug delivery vehicle for pharmaceutical purposes.
    Matched MeSH terms: Polymers/chemistry
  2. Potential of using multiscale corn husk fiber as reinforcing filler in cornstarch-based biocomposites
    Ibrahim MIJ, Sapuan SM, Zainudin ES, Zuhri MYM
    Int J Biol Macromol, 2019 Oct 15;139:596-604.
    PMID: 31381916 DOI: 10.1016/j.ijbiomac.2019.08.015
    In this study, biodegradable composite films were prepared by using thermoplastic cornstarch matrix and corn husk fiber as a reinforcing filler. The composite films were manufactured via a casting technique using different concentrations of husk fiber (0-8%), and fructose as a plasticizer at a fixed amount of 25% for starch weight. The Physical, thermal, morphological, and tensile characteristics of composite films were investigated. The findings indicated that the incorporation of husk fiber, in general, enhanced the performance of the composite films. There was a noticeable reduction in the density and moisture content of the films, and soil burial assessment showed less resistance to biodegradation. The morphological images presented a consistent structure and excellent compatibility between matrix and reinforcement, which reflected on the improved tensile strength and young modulus as well as the crystallinity index. The thermal stability of composite films has also been enhanced, as evidenced by the increased onset decomposition temperature of the reinforced films compared to neat film. Fourier transform infrared analysis revealed increasing in intermolecular hydrogen bonding following fiber loading. The composite materials prepared using corn husk residues as reinforcement responded to community demand for agricultural and polymeric waste disposal and added more value to waste management.
    Matched MeSH terms: Polymers/chemistry*
  3. Fulltext A novel aqueous two phase system composed of a thermo-separating polymer and an organic solvent for purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel
    Amid M, Manap Y, Zohdi NK
    Molecules, 2014 May 22;19(5):6635-50.
    PMID: 24858097 DOI: 10.3390/molecules19056635
    The purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel for the first time was investigated using a novel aqueous two-phase system (ATPS) consisting of a thermo-separating copolymer and an organic solvent. The effectiveness of different parameters such as molecular weight of the thermo-separating ethylene oxide-propylene oxide (EOPO) copolymer and type and concentration of organic solvent on the partitioning behavior of amylase was investigated. In addition, the effects of phase components, volume ratio (VR), pH and crude load of purification factor and yield of amylase were evaluated to achieve the optimum partition conditions of the enzyme. In the novel ATPS method, the enzyme was satisfactorily partitioned into the polymer-rich top phase in the system composed of 30% (w/w) EOPO 2500 and 15% (w/w) 2-propanol, at a volume ratio of 1.94 and with a crude load scale of 25% (w/w) at pH 5.0. Recovery and recycling of components was also measured in each successive step of the ATPS process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 96.6% and copolymer was also recovered and recycled at a rate above 97%, making the method was more economical than the traditional ATPS method.
    Matched MeSH terms: Polymers/chemistry
  4. Partial replacement effect of montmorillonite with cellulose nanowhiskers on polylactic acid nanocomposites
    Arjmandi R, Hassan A, Mohamad Haafiz MK, Zakaria Z
    Int J Biol Macromol, 2015 Nov;81:91-9.
    PMID: 26234577 DOI: 10.1016/j.ijbiomac.2015.07.062
    In this study, hybrid montmorillonite/cellulose nanowhiskers (MMT/CNW) reinforced polylactic acid (PLA) nanocomposites were produced through solution casting. The CNW filler was first isolated from microcrystalline cellulose by chemical swelling technique. The partial replacement of MMT with CNW in order to produce PLA/MMT/CNW hybrid nanocomposites was performed at 5 parts per hundred parts of polymer (phr) fillers content, based on highest tensile strength values as reported in our previous study. MMT were partially replaced with various amounts of CNW (1, 2, 3, 4 and 5phr). The tensile, thermal, morphological and biodegradability properties of PLA hybrid nanocomposites were investigated. The highest tensile strength of hybrid nanocomposites was obtained with the combination of 4phr MMT and 1phr CNW. Interestingly, the ductility of hybrid nanocomposites increased significantly by 79% at this formulation. The Young's modulus increased linearly with increasing CNW content. Thermogravimetric analysis illustrated that the partial replacement of MMT with CNW filler enhanced the thermal stability of the PLA. This is due to the relatively good dispersion of fillers in the hybrid nanocomposites samples as revealed by transmission electron microscopy. Interestingly, partial replacements of MMT with CNW improved the biodegradability of hybrid nanocomposites compared to PLA/MMT and neat PLA.
    Matched MeSH terms: Polymers/chemistry*
  5. Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay
    Adzmi F, Meon S, Musa MH, Yusuf NA
    J Microencapsul, 2012;29(3):205-10.
    PMID: 22309479 DOI: 10.3109/02652048.2012.659286
    Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p 
    Matched MeSH terms: Polymers/chemistry
  6. Removal of bisphenol A by adsorption mechanism using PES-SiO2 composite membranes
    Muhamad MS, Salim MR, Lau WJ, Hadibarata T, Yusop Z
    Environ Technol, 2016 Aug;37(15):1959-69.
    PMID: 26729509 DOI: 10.1080/09593330.2015.1137359
    Polyethersulphone (PES) membranes blended with silicon dioxide (SiO2) nanoparticles were prepared via a dry-jet wet spinning technique for the removal of bisphenol A (BPA) by adsorption mechanism. The morphology of SiO2 nanoparticles was analysed using a transmission electron microscopy and particle size distribution was also analysed. The prepared membranes were characterized by several techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy and water contact angle. The adsorption mechanism of membrane towards BPA was evaluated by batch experiments and kinetic model. The influence of natural organic matter (NOM) in feed water on membrane BPA removal was also studied by filtration experiments. Results showed that BPA adsorption capacity as high as 53 µg/g could be achieved by the PES membrane incorporated with 2 wt% SiO2 in which the adsorption mechanism was in accordance with the pseudo-second-order kinetic model. The intraparticles diffusion model suggested that the rate limiting factor of membrane adsorption mechanism is governed by the diffusion of BPA into the membrane pores. The presence of 10 ppm NOM has reported to negatively reduce BPA removal by 24%, as it tended to compete with BPA for membrane adsorption. This work has demonstrated that PES-SiO2 membrane has the potential to eliminate trace amount of BPA from water source containing NOM.
    Matched MeSH terms: Polymers/chemistry*
  7. Nylon 6,6 modified screen printed carbon electrodes as electrochemical sensors for rapid chlorothalonil determination in water samples using differential pulse cathodic stripping voltammetry
    Thanalechumi P, Mohd Yusoff AR, Yusop Z
    J Environ Sci Health B, 2019;54(4):294-302.
    PMID: 30729855 DOI: 10.1080/03601234.2018.1561057
    A newly developed electrochemical sensor for chlorothalonil based on nylon 6,6 film deposited onto screen printed electrode (SPE) with electrochemical modulation of pH at the electrode/solution interface was studied for the first time. Differential pulse cathodic stripping voltammetry (DPCSV) was used to carry out the electrochemical and analytical studies. Experimental parameters such as accumulation potential, initial potential, accumulation time and pH of Britton-Robinson buffer have been optimized. Chlorothalonil gave optimum analytical signal in a medium of 0.04 M Britton-Robinson buffer at pH 6.0. A well-defined reduction peak was observed, at Ep= -0.851 and -0.938 V vs. Ag/AgCl (3.0 M KCl) for both bare SPE and modified SPE, respectively. The peak currents of modified SPE were significantly increased as compared to bare SPE. At the modified SPE, a linear relationship between the peak current and chlorothalonil concentration was obtained in the range from 0.1 to 2.8 × 10-6 M with a detection limit of 1.53 × 10-8 M (S/N= 3). The practical applicability of the newly developed method has been demonstrated on analyses of real water samples. The newly developed sensor shows good reproducibility with RSD of 3.92%. The nylon 6,6 modified SPE showed itself as promising sensor with good selectivity for chlorothalonil determination.
    Matched MeSH terms: Polymers/chemistry
  8. Fabrication, characterization and application of laccase-nylon 6,6/Fe(3+) composite nanofibrous membrane for 3,3'-dimethoxybenzidine detoxification
    Jasni MJ, Sathishkumar P, Sornambikai S, Yusoff AR, Ameen F, Buang NA, et al.
    Bioprocess Biosyst Eng, 2017 Feb;40(2):191-200.
    PMID: 27757535 DOI: 10.1007/s00449-016-1686-6
    In this study, laccase was immobilized on nylon 6,6/Fe(3+) composite (NFC) nanofibrous membrane and used for the detoxification of 3,3'-dimethoxybenzidine (DMOB). The average size and tensile strength of the NFC membrane were found to be 60-80 nm (diameter) and 2.70 MPa, respectively. The FTIR results confirm that the amine (N-H) group of laccase was attached with Fe(3+) particles and the carbonyl (C=O) group of NFC membrane via hydrogen bonding. The half-life of the laccase-NFC membrane storage stability was increased from 6 to 11 weeks and the reusability was significantly extended up to 43 cycles against ABTS oxidation. Enhanced electro-oxidation of DMOB by laccase was observed at 0.33 V and the catalytic current was found to be 30 µA. The DMOB-treated mouse fibroblast 3T3-L1 preadipocytes showed maximum (97 %) cell inhibition at 75 µM L(-1) within 24 h. The cytotoxicity of DMOB was significantly decreased to 78 % after laccase treatment. This study suggests that laccase-NFC membrane might be a good candidate for emerging pollutant detoxification.
    Matched MeSH terms: Polymers/chemistry*
  9. Response surface methodology analysis of the photocatalytic removal of Methylene Blue using bismuth vanadate prepared via polyol route
    Abdullah AH, Moey HJ, Yusof NA
    J Environ Sci (China), 2012;24(9):1694-701.
    PMID: 23520879
    Visible-light driven photocatalyst bismuth vanadate (BiVO4) photocatalyst was synthesized by the polyol route using ethylene glycol. The precipitate was washed, dried and calcined at 450 degrees C for 3 hr. The sample was characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FE-SEM), zeta potential, surface area (BET method) and band gap energy via diffuse reflectance spectroscopy (DRS). The synthesized BiVO4 has a monoclinic phase with a surface area of 4.3 m2/g and a band gap energy of 2.46 eV. A majority of the particles were in the range of 90-130 nm as obtained from the particle size distribution histrogram. The efficiency of the sample as a visible-light driven photocatalyst was examined by photodegrading Methylene Blue (MB). The effects of some operational photodegradation parameters such as mass loading, initial dye concentration and pH were also examined. Experimental design methodology was applied by response surface modeling and optimization of the removal of MB. The multivariate experimental design was employed to develop a quadratic model as a functional relationship between the percentage removal of MB and three experimental factors (BiVO4 loading, MB initial concentration and pH). The percentage removal of MB approached 67.21% under optimized conditions. In addition, a satisfactory goodness-of-fit was achieved between the,predictive and the experimental results.
    Matched MeSH terms: Polymers/chemistry*
  10. Doxorubicin-loaded micelles of amphiphilic diblock copolymer with pendant dendron improve antitumor efficacy: In vitro and in vivo studies
    Voon SH, Kue CS, Imae T, Saw WS, Lee HB, Kiew LV, et al.
    Int J Pharm, 2017 Dec 20;534(1-2):136-143.
    PMID: 29031979 DOI: 10.1016/j.ijpharm.2017.10.023
    Previously reported amphiphilic diblock copolymer with pendant dendron moieties (P71D3) has been further evaluated in tumor-bearing mice as a potential drug carrier. This P71D3-based micelle of an average diameter of 100nm was found to be biocompatible, non-toxic and physically stable in colloidal system up to 15days. It enhanced the in vitro potency of doxorubicin (DOX) in 4T1 breast tumor cells by increasing its uptake, by 3-fold, compared to free DOX. In 4T1 tumor-bearing mice, the tumor growth rate of P71D3/DOX (2mg/kg DOX equivalent) treated group was significantly delayed and their tumor volume was significantly reduced by 1.5-fold compared to those treated with free DOX. The biodistribution studies indicated that P71D3/DOX enhanced accumulation of DOX in tumor by 5- and 2-fold higher than free DOX treated mice at 15min and 1h post-administration, respectively. These results suggest that P71D3 micelle is a promising nanocarrier for chemotherapeutic agents.
    Matched MeSH terms: Polymers/chemistry*
  11. Fulltext Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites
    Eng CC, Ibrahim NA, Zainuddin N, Ariffin H, Yunus WM
    ScientificWorldJournal, 2014;2014:213180.
    PMID: 25254230 DOI: 10.1155/2014/213180
    Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.
    Matched MeSH terms: Polymers/chemistry*
  12. Fulltext Degradability enhancement of poly(lactic acid) by stearate-Zn(3)Al LDH nanolayers
    Eili M, Shameli K, Ibrahim NA, Yunus WM
    Int J Mol Sci, 2012;13(7):7938-51.
    PMID: 22942682 DOI: 10.3390/ijms13077938
    Recent environmental problems and societal concerns associated with the disposal of petroleum based plastics throughout the world have triggered renewed efforts to develop new biodegradable products compatible with our environment. This article describes the preparation, characterization and biodegradation study of poly(lactic acid)/layered double hydroxide (PLA/LDH) nanocomposites from PLA and stearate-Zn(3)Al LDH. A solution casting method was used to prepare PLA/stearate-Zn(3)Al LDH nanocomposites. The anionic clay Zn(3)Al LDH was firstly prepared by co-precipitation method from a nitrate salt solution at pH 7.0 and then modified by stearate anions through an ion exchange reaction. This modification increased the basal spacing of the synthetic clay from 8.83 Å to 40.10 Å. The morphology and properties of the prepared PLA/stearate-Zn(3)Al LDH nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), thermogravimetric analysis (TGA), tensile tests as well as biodegradation studies. From the XRD analysis and TEM observation, the stearate-Zn(3)Al LDH lost its ordered stacking-structure and was greatly exfoliated in the PLA matrix. Tensile test results of PLA/stearate-Zn(3)Al LDH nanocomposites showed that the presence of around 1.0-3.0 wt % of the stearate-Zn(3)Al LDH in the PLA drastically improved its elongation at break. The biodegradation studies demonstrated a significant biodegradation rate improvement of PLA in the presence of stearate-Zn(3)Al LDH nanolayers. This effect can be caused by the catalytic role of the stearate groups in the biodegradation mechanism leading to much faster disintegration of nanocomposites than pure PLA.
    Matched MeSH terms: Polymers/chemistry*
  13. Fulltext Application of supercritical antisolvent method in drug encapsulation: a review
    Kalani M, Yunus R
    Int J Nanomedicine, 2011;6:1429-42.
    PMID: 21796245 DOI: 10.2147/IJN.S19021
    The review focuses on the application of supercritical fluids as antisolvents in the pharmaceutical field and demonstrates the supercritical antisolvent method in the use of drug encapsulation. The main factors for choosing the solvent and biodegradable polymer to produce fine particles to ensure effective drug delivery are emphasized and the effect of polymer structure on drug encapsulation is illustrated. The review also demonstrates the drug release mechanism and polymeric controlled release system, and discusses the effects of the various conditions in the process, such as pressure, temperature, concentration, chemical compositions (organic solvents, drug, and biodegradable polymer), nozzle geometry, CO(2) flow rate, and the liquid phase flow rate on particle size and its distribution.
    Matched MeSH terms: Polymers/chemistry
  14. Accuracy of a new elastomeric impression material for complete-arch dental implant impressions
    Baig MR, Buzayan MM, Yunus N
    J Investig Clin Dent, 2018 May;9(2):e12320.
    PMID: 29349910 DOI: 10.1111/jicd.12320
    AIM: The aim of the present study was to assess the accuracy of multi-unit dental implant casts obtained from two elastomeric impression materials, vinyl polyether silicone (VPES) and polyether (PE), and to test the effect of splinting of impression copings on the accuracy of implant casts.

    METHODS: Forty direct impressions of a mandibular reference model fitted with six dental implants and multibase abutments were made using VPES and PE, and implant casts were poured (N = 20). The VPES and PE groups were split into four subgroups of five each, based on splinting type: (a) no splinting; (b) bite registration polyether; (c) bite registration addition silicone; and (d) autopolymerizing acrylic resin. The accuracy of implant-abutment replica positions was calculated on the experimental casts, in terms of interimplant distances in the x, y, and z-axes, using a coordinate measuring machine; values were compared with those measured on the reference model. Data were analyzed using non-parametrical Kruskal-Wallis and Mann-Whitney tests at α = .05.

    RESULTS: The differences between the two impression materials, VPES and PE, regardless of splinting type, were not statistically significant (P>.05). Non-splinting and splinting groups were also not significantly different for both PE and VPES (P>.05).

    CONCLUSIONS: The accuracy of VPES impression material seemed comparable with PE for multi-implant abutment-level impressions. Splinting had no effect on the accuracy of implant impressions.

    Matched MeSH terms: Polymers/chemistry*
  15. Fulltext Optimization of NaOH Molarity, LUSI Mud/Alkaline Activator, and Na2SiO3/NaOH Ratio to Produce Lightweight Aggregate-Based Geopolymer
    Razak RA, Abdullah MM, Hussin K, Ismail KN, Hardjito D, Yahya Z
    Int J Mol Sci, 2015;16(5):11629-47.
    PMID: 26006238 DOI: 10.3390/ijms160511629
    This paper presents the mechanical function and characterization of an artificial lightweight geopolymer aggregate (ALGA) using LUSI (Sidoarjo mud) and alkaline activator as source materials. LUSI stands for LU-Lumpur and SI-Sidoarjo, meaning mud from Sidoarjo which erupted near the Banjarpanji-1 exploration well in Sidoarjo, East Java, Indonesia on 27 May 2006. The effect of NaOH molarity, LUSI mud/Alkaline activator (LM/AA) ratio, and Na2SiO3/NaOH ratio to the ALGA are investigated at a sintering temperature of 950 °C. The results show that the optimum NaOH molarity found in this study is 12 M due to the highest strength (lowest AIV value) of 15.79% with lower water absorption and specific gravity. The optimum LUSI mud/Alkaline activator (LM/AA) ratio of 1.7 and the Na2SiO3/NaOH ratio of 0.4 gives the highest strength with AIV value of 15.42% with specific gravity of 1.10 g/cm3 and water absorption of 4.7%. The major synthesized crystalline phases were identified as sodalite, quartz and albite. Scanning Electron Microscope (SEM) image showed more complete geopolymer matrix which contributes to highest strength of ALGA produced.
    Matched MeSH terms: Polymers/chemistry*
  16. Molecularly imprinted silica gel incorporated with agarose polymer matrix as mixed matrix membrane for separation and preconcentration of sulfonamide antibiotics in water samples
    Rozaini MNH, Semail NF, Saad B, Kamaruzaman S, Abdullah WN, Rahim NA, et al.
    Talanta, 2019 Jul 01;199:522-531.
    PMID: 30952293 DOI: 10.1016/j.talanta.2019.02.096
    Molecularly imprinted silica gel (MISG) was incorporated through dispersion in agarose polymer matrix to form a mixed matrix membrane (MMM) and was applied for the determination of three sulfonamide antibiotic compounds (i.e. sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ)) from environmental water samples. Several important microextraction conditions, such as type of desorption solvent, extraction time, amount of sorbent, sample volume, pH, and effect of desorption time, were comprehensively optimized. A preconcentration factors of ≥ 20 was achieved by the extraction of 12.5 mL of water samples using the developed method. This microextraction-HPLC method demonstrated good linearity (1-500 μg L-1) with a coefficient of determination (R2) of 0.9959-0.9999, low limits of detection (0.06-0.17 μg L-1) and limits of quantification (0.20-0.56 μg L-1), good analyte recoveries (80-96%), and acceptable relative standard deviations (< 10%) under the optimized conditions. The method is systematically compared to those reported in the literature.
    Matched MeSH terms: Polymers/chemistry*
  17. Challenges and strategies in the preparation of large-volume polymer-based monolithic chromatography adsorbents
    Ongkudon CM, Kansil T, Wong C
    J Sep Sci, 2014 Mar;37(5):455-64.
    PMID: 24376196 DOI: 10.1002/jssc.201300995
    To date, the number of published reports on the large-volume preparation of polymer-based monolithic chromatography adsorbents is still lacking and is of great importance. Many critical factors need to be considered when manufacturing a large-volume polymer-based monolith for chromatographic applications. Structural integrity, validity, and repeatability are thought to be the key factors determining the usability of a large-volume monolith in a separation process. In this review, we focus on problems and solutions pertaining to heat dissipation, pore size distribution, "wall channel" effect, and mechanical strength in monolith preparation. A template-based method comprising sacrificial and nonsacrificial techniques is possibly the method of choice due to its precise control over the porous structure. However, additional expensive steps are usually required for the template removal. Other strategies in monolith preparation are also discussed.
    Matched MeSH terms: Polymers/chemistry*
  18. Fulltext A comparative study on the mechanical, thermal and morphological characterization of poly(lactic acid)/epoxidized Palm Oil blend
    Giita Silverajah VS, Ibrahim NA, Yunus WM, Hassan HA, Woei CB
    Int J Mol Sci, 2012;13(5):5878-98.
    PMID: 22754338 DOI: 10.3390/ijms13055878
    In this work, poly(lactic acid) (PLA) a fully biodegradable thermoplastic polymer matrix was melt blended with three different epoxidized palm oil (EPO). The aim of this research was to enhance the flexibility, mechanical and thermal properties of PLA. The blends were prepared at various EPO contents of 1, 2, 3, 4 and 5 wt% and characterized. The SEM analysis evidenced successful modification on the neat PLA brittle morphology. Tensile tests indicate that the addition of 1 wt% EPO is sufficient to improve the strength and flexibility compared to neat PLA. Additionally, the flexural and impact properties were also enhanced. Further, DSC analysis showed that the addition of EPO results in a decrease in T(g), which implies an increase in the PLA chain mobility. In the presence of 1 wt% EPO, TGA results revealed significant increase in the thermal stability by 27%. Among the three EPOs used, EPO(3) showed the best mechanical and thermal properties compared to the other EPO's, with an optimum loading of 1 wt%. Conclusively, EPO showed a promising outcome to overcome the brittleness and improve the overall properties of neat PLA, thus can be considered as a potential plasticizer.
    Matched MeSH terms: Polymers/chemistry*
  19. Fulltext Recent Advances in Electrochemical and Optical Sensing of Dopamine
    Kamal Eddin FB, Wing Fen Y
    Sensors (Basel), 2020 Feb 14;20(4).
    PMID: 32075167 DOI: 10.3390/s20041039
    Nowadays, several neurological disorders and neurocrine tumours are associated with dopamine (DA) concentrations in various biological fluids. Highly accurate and ultrasensitive detection of DA levels in different biological samples in real-time can change and improve the quality of a patient's life in addition to reducing the treatment cost. Therefore, the design and development of diagnostic tool for in vivo and in vitro monitoring of DA is of considerable clinical and pharmacological importance. In recent decades, a large number of techniques have been established for DA detection, including chromatography coupled to mass spectrometry, spectroscopic approaches, and electrochemical (EC) methods. These methods are effective, but most of them still have some drawbacks such as consuming time, effort, and money. Added to that, sometimes they need complex procedures to obtain good sensitivity and suffer from low selectivity due to interference from other biological species such as uric acid (UA) and ascorbic acid (AA). Advanced materials can offer remarkable opportunities to overcome drawbacks in conventional DA sensors. This review aims to explain challenges related to DA detection using different techniques, and to summarize and highlight recent advancements in materials used and approaches applied for several sensor surface modification for the monitoring of DA. Also, it focuses on the analytical features of the EC and optical-based sensing techniques available.
    Matched MeSH terms: Polymers/chemistry
  20. Fulltext Floating ZnO QDs-Modified TiO2/LLDPE Hybrid Polymer Film for the Effective Photodegradation of Tetracycline under Fluorescent Light Irradiation: Synthesis and Characterisation
    Iqbal A, Saidu U, Adam F, Sreekantan S, Yahaya N, Ahmad MN, et al.
    Molecules, 2021 Apr 25;26(9).
    PMID: 33923041 DOI: 10.3390/molecules26092509
    In this work, mesoporous TiO2-modified ZnO quantum dots (QDs) were immobilised on a linear low-density polyethylene (LLDPE) polymer using a solution casting method for the photodegradation of tetracycline (TC) antibiotics under fluorescent light irradiation. Various spectroscopic and microscopic techniques were used to investigate the physicochemical properties of the floating hybrid polymer film catalyst (8%-ZT@LLDPE). The highest removal (89.5%) of TC (40 mg/L) was achieved within 90 min at pH 9 due to enhanced water uptake by the LDDPE film and the surface roughness of the hybrid film. The formation of heterojunctions increased the separation of photogenerated electron-hole pairs. The QDs size-dependent quantum confinement effect leads to the displacement of the conduction band potential of ZnO QDs to more negative energy values than TiO2. The displacement generates more reactive species with higher oxidation ability. The highly stable film photocatalyst can be separated easily and can be repeatedly used up to 8 cycles without significant loss in the photocatalytic ability. The scavenging test indicates that the main species responsible for the photodegradation was O2●-. The proposed photodegradation mechanism of TC was demonstrated in further detail based on the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS).
    Matched MeSH terms: Polymers/chemistry*
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