Displaying publications 61 - 80 of 225 in total

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  1. Co-incorporation of graphene oxide/silver nanoparticle into poly-L-lactic acid fibrous: A route toward the development of cytocompatible and antibacterial coating layer on magnesium implants
    Bakhsheshi-Rad HR, Ismail AF, Aziz M, Akbari M, Hadisi Z, Khoshnava SM, et al.
    Mater Sci Eng C Mater Biol Appl, 2020 Jun;111:110812.
    PMID: 32279830 DOI: 10.1016/j.msec.2020.110812
    Magnesium (Mg) alloys present great potential for the development of orthopedic implants, whereas, their high degradation rate and poor antibacterial performance have restricted orthopedic applications. In this work, PLLA/GO-AgNP (poly-L-lactic acid/graphene oxide- silver nanoparticle) with different concentration of GO-AgNPs were deposited on Mg alloy via electrospinning method for enhancement of corrosion resistance and antibacterial performance. The result revealed that incorporation of GO into PLLA fibrous considerably slowed down the degradation rate of Mg alloy substrate and reduced the H2 release rate from the substrate. Also, co-incorporation of GO and AgNPs into PLLA fibrous resulted in substantial escalate in compressive strength after immersion in simulated body fluid (SBF). Antibacterial activity test exhibited that Mg alloy and neat PLLA fibrous presented minimal inhibition area toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In contrast, using PLLA/GO-AgNPs fibrous improved antibacterial performance against both bacteria. Cytocompatibility results indicated that PLLA/GO-AgNPs fibrous with a low amount of GO-AgNPs enhanced cell proliferation and growth while high co-incorporation of GO-AgNPs showed a negative effect on cell proliferation. Taken together, PLLA/1GO-AgNPs fibrous coating shows suitable corrosion resistance, cytocompatibility, and antibacterial function for use in orthopedic applications.
    Matched MeSH terms: Polyesters/pharmacology*
  2. Fulltext Oxygen-Releasing Antibacterial Nanofibrous Scaffolds for Tissue Engineering Applications
    Abudula T, Gauthaman K, Hammad AH, Joshi Navare K, Alshahrie AA, Bencherif SA, et al.
    Polymers (Basel), 2020 May 29;12(6).
    PMID: 32485817 DOI: 10.3390/polym12061233
    Lack of suitable auto/allografts has been delaying surgical interventions for the treatment of numerous disorders and has also caused a serious threat to public health. Tissue engineering could be one of the best alternatives to solve this issue. However, deficiency of oxygen supply in the wounded and implanted engineered tissues, caused by circulatory problems and insufficient angiogenesis, has been a rate-limiting step in translation of tissue-engineered grafts. To address this issue, we designed oxygen-releasing electrospun composite scaffolds, based on a previously developed hybrid polymeric matrix composed of poly(glycerol sebacate) (PGS) and poly(ε-caprolactone) (PCL). By performing ball-milling, we were able to embed a large percent of calcium peroxide (CP) nanoparticles into the PGS/PCL nanofibers able to generate oxygen. The composite scaffold exhibited a smooth fiber structure, while providing sustainable oxygen release for several days to a week, and significantly improved cell metabolic activity due to alleviation of hypoxic environment around primary bone-marrow-derived mesenchymal stem cells (BM-MSCs). Moreover, the composite scaffolds also showed good antibacterial performance. In conjunction to other improved features, such as degradation behavior, the developed scaffolds are promising biomaterials for various tissue-engineering and wound-healing applications.
    Matched MeSH terms: Polyesters
  3. Fulltext Asymmetric Open-Closed Dimer Mechanism of Polyhydroxyalkanoate Synthase PhaC
    Chek MF, Kim SY, Mori T, Tan HT, Sudesh K, Hakoshima T
    iScience, 2020 May 22;23(5):101084.
    PMID: 32388399 DOI: 10.1016/j.isci.2020.101084
    Biodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its β-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291.
    Matched MeSH terms: Polyesters
  4. Osteoblasts migration, attachment and human bone marrow-mesenchymal stem cells osteogenic differentiation towards surface engineered and growth factors conjugated poly(lactic acid) microspheres
    Mohd Sabee MMS, Kamalaldin NA, Yahaya BH, Abdul Hamid ZA
    J Mater Sci Mater Med, 2020 May 04;31(5):45.
    PMID: 32367409 DOI: 10.1007/s10856-020-06380-y
    Recently, surface engineered biomaterials through surface modification are extensively investigated due to its potential to enhance cellular homing and migration which contributes to a successful drug delivery process. This study is focused on osteoblasts response towards surface engineered using a simple sodium hydroxide (NaOH) hydrolysis and growth factors conjugated poly(lactic acid) (PLA) microspheres. In this study, evaluation of the relationship of NaOH concentration with the molecular weight changes and surface morphology of PLA microspheres specifically wall thickness and porosity prior to in vitro studies was investigated. NaOH hydrolysis of 0.1 M, 0.3 M and 0.5 M were done to introduce hydrophilicity on the PLA prior to conjugation with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). Morphology changes showed that higher concentration of NaOH could accelerate the hydrolysis process as the highest wall thickness was observed at 0.5 M NaOH with ~3.52 µm. All surface modified and growth factors conjugated PLA microspheres wells enhanced the migration of the cells during wound healing process as wound closure was 100% after 3 days of treatment. Increase in hydrophilicity of the surface engineered and growth factors conjugated PLA microspheres provides favorable surface for cellular attachment of osteoblast, which was reflected by positive DAPI staining of the cells' nucleus. Surface modified and growth factors conjugated PLA microspheres were also able to enhance the capability of the PLA in facilitating the differentiation process of mesenchymal stem cells (MSCs) into osteogenic lineage since only positive stain was observed on surface engineered and growth factors conjugated PLA microspheres. These results indicated that the surface engineered and growth factors conjugated PLA microspheres were non-toxic for biological environments and the improved hydrophilicity made them a potential candidate as a drug delivery vehicle as the cells can adhere, attach and proliferate inside it.
    Matched MeSH terms: Polyesters/chemistry*
  5. Fulltext Liquid-Crystal and Fire-Retardant Properties of New Hexasubstituted Cyclotriphosphazene Compounds with Two Schiff Base Linking Units
    Jamain Z, Khairuddean M, Guan-Seng T
    Molecules, 2020 May 01;25(9).
    PMID: 32370000 DOI: 10.3390/molecules25092122
    A series of new hexasubstituted cyclotriphosphazene compounds (4a-j) consisting of two Schiff base linking units and different terminal substituents was successfully synthesized and characterized. The structures of these compounds were confirmed using Fourier Transform Infra-Red (FTIR), Nuclear Magnetic Resonance (NMR), and CHN elemental analysis. Polarized optical microscopy (POM) was used to determine their liquid-crystal behavior, which was then further confirmed using differential scanning calorimetry (DSC). Compounds 4a-i with heptyl, nonyl, decyl, dodecyl, tetradecyl, hydroxy, 4-carboxyphenyl, chloro, and nitro terminal ends, respectively, showed the liquid-crystal properties, whereas compound 4j with the amino group was found to be non-mesogenic. The attachment of an electron-donating group in 4j eventually give a non-mesogenic product. The study of the fire-retardant properties of these compounds was done using the limiting oxygen index (LOI). In this study, polyester resin (PE) was used as a matrix for moulding, and the LOI value of pure PE was 22.53%. The LOI value increased to 24.71% when PE was incorporated with 1 wt.% of hexachlorocyclotriphosphazene (HCCP), thus indicating that HCCP has a good fire-retardant properties. The result showed that all the compounds have good agreement in their LOI values. Compound 4i with a nitro terminal group gave the highest LOI value of 28.37%.
    Matched MeSH terms: Polyesters
  6. Fulltext Neutron-activated biodegradable samarium-153 acetylacetonate-poly-L-lactic acid microspheres for intraarterial radioembolization of hepatic tumors
    Wong YH, Tan HY, Kasbollah A, Abdullah BJJ, Acharya RU, Yeong CH
    World J Exp Med, 2020 Mar 30;10(2):10-25.
    PMID: 32266125 DOI: 10.5493/wjem.v10.i2.10
    BACKGROUND: Liver cancer is the 6th most common cancer in the world and the 4th most common death from cancer worldwide. Hepatic radioembolization is a minimally invasive treatment involving intraarterial administration of radioembolic microspheres.

    AIM: To develop a neutron-activated, biodegradable and theranostics samarium-153 acetylacetonate (153SmAcAc)-poly-L-lactic acid (PLLA) microsphere for intraarterial radioembolization of hepatic tumors.

    METHODS: Microspheres with different concentrations of 152SmAcAc (i.e., 100%, 150%, 175% and 200% w/w) were prepared by solvent evaporation method. The microspheres were then activated using a nuclear reactor in a neutron flux of 2 × 1012 n/cm2/s1, converting 152Sm to Samarium-153 (153Sm) via152Sm (n, γ) 153Sm reaction. The SmAcAc-PLLA microspheres before and after neutron activation were characterized using scanning electron microscope, energy dispersive X-ray spectroscopy, particle size analysis, Fourier transform infrared spectroscopy, thermo-gravimetric analysis and gamma spectroscopy. The in-vitro radiolabeling efficiency was also tested in both 0.9% sodium chloride solution and human blood plasma over a duration of 550 h.

    RESULTS: The SmAcAc-PLLA microspheres with different SmAcAc contents remained spherical before and after neutron activation. The mean diameter of the microspheres was about 35 µm. Specific activity achieved for 153SmAcAc-PLLA microspheres with 100%, 150%, 175% and 200% (w/w) SmAcAc after 3 h neutron activation were 1.7 ± 0.05, 2.5 ± 0.05, 2.7 ± 0.07, and 2.8 ± 0.09 GBq/g, respectively. The activity of per microspheres were determined as 48.36 ± 1.33, 74.10 ± 1.65, 97.87 ± 2.48, and 109.83 ± 3.71 Bq for 153SmAcAc-PLLA microspheres with 100%, 150%, 175% and 200% (w/w) SmAcAc. The energy dispersive X-ray and gamma spectrometry showed that no elemental and radioactive impurities present in the microspheres after neutron activation. Retention efficiency of 153Sm in the SmAcAc-PLLA microspheres was excellent (approximately 99%) in both 0.9% sodium chloride solution and human blood plasma over a duration of 550 h.

    CONCLUSION: The 153SmAcAc-PLLA microsphere is potentially useful for hepatic radioembolization due to their biodegradability, favorable physicochemical characteristics and excellent radiolabeling efficiency. The synthesis of the formulation does not involve ionizing radiation and hence reducing the complication and cost of production.

    Matched MeSH terms: Polyesters
  7. Fulltext The Role of Two-Step Blending in the Properties of Starch/Chitin/Polylactic Acid Biodegradable Composites for Biomedical Applications
    Olaiya NG, Nuryawan A, Oke PK, Khalil HPSA, Rizal S, Mogaji PB, et al.
    Polymers (Basel), 2020 Mar 05;12(3).
    PMID: 32151004 DOI: 10.3390/polym12030592
    The current research trend for excellent miscibility in polymer mixing is the use of plasticizers. The use of most plasticizers usually has some negative effects on the mechanical properties of the resulting composite and can sometimes make it toxic, which makes such polymers unsuitable for biomedical applications. This research focuses on the improvement of the miscibility of polymer composites using two-step mixing with a rheomixer and a mix extruder. Polylactic acid (PLA), chitin, and starch were produced after two-step mixing, using a compression molding method with decreasing composition variation (between 8% to 2%) of chitin and increasing starch content. A dynamic mechanical analysis (DMA) was used to study the mechanical behavior of the composite at various temperatures. The tensile strength, yield, elastic modulus, impact, morphology, and compatibility properties were also studied. The DMA results showed a glass transition temperature range of 50 °C to 100 °C for all samples, with a distinct peak value for the loss modulus and factor. The single distinct peak value meant the polymer blend was compatible. The storage and loss modulus increased with an increase in blending, while the loss factor decreased, indicating excellent compatibility and miscibility of the composite components. The mechanical properties of the samples improved compared to neat PLA. Small voids and immiscibility were noticed in the scanning electron microscopy images, and this was corroborated by X-ray diffraction graphs that showed an improvement in the crystalline nature of PLA with starch. Bioabsorption and toxicity tests showed compatibility with the rat system, which is similar to the human system.
    Matched MeSH terms: Polyesters
  8. Electrospun poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/silk fibroin film is a promising scaffold for bone tissue engineering
    Ang SL, Shaharuddin B, Chuah JA, Sudesh K
    Int J Biol Macromol, 2020 Feb 15;145:173-188.
    PMID: 31866541 DOI: 10.1016/j.ijbiomac.2019.12.149
    Polyhydroxyalkanoates (PHAs) are biodegradable polyesters produced by microorganisms, under unbalanced growth conditions, as a carbon storage compound. PHAs are composed of various monomers such as 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HHx). Silk fibroin (SF) derived from Bombyx mori cocoons, is a widely studied protein polymer commonly used for biomaterial applications. In this study, non-woven electrospun films comprising a copolymer of 3HB and 3HHx [P(3HB-co-3HHx)], SF and their blends were prepared by electrospinning technique. The growth and osteogenic differentiation of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) were studied using different types of fabricated electrospun films. The differentiation study revealed that electrospun P(3HB-co-3HHx)/SF film supports the differentiation of hUC-MSCs into the osteogenic lineage, confirmed by histological analysis using Alizarin Red staining, energy dispersive X-ray (EDX) and quantitative real-time PCR analysis (qPCR). Electrospun P(3HB-co-3HHx)/SF film up-regulated the expression of osteogenic marker genes, alkaline phosphatase (ALP) and osteocalcin (OCN), by 1.6-fold and 2.8-fold respectively, after 21 days of osteogenic induction. In conclusion, proliferation and osteogenic differentiation of hUC-MSCs were enhanced through the blending of P(3HB-co-3HHx) and SF. The results from this study suggest that electrospun P(3HB-co-3HHx)/SF film is a promising biomaterial for bone tissue engineering.
    Matched MeSH terms: Polyesters
  9. Fulltext Data on the effect of electrospinning parameters on the morphology of the nanofibrous poly(3-hydroxybutyrate-co-4-hydroxybutyrate) scaffolds
    Chai CJ, Amirul AA, Vigneswari S
    Data Brief, 2020 Feb;28:104777.
    PMID: 31871967 DOI: 10.1016/j.dib.2019.104777
    Electrospinning is a promising approach to fabricate desirable electropsun nanofibrous scaffold that could be applied in the medical fields. In this study, bacterial copolymer poly(3-hydroxybutyrate-co-68 mol% 4-hydroxybutyrate) [P(3HB-co-68mol% 4HB)] copolymer produced was fabricated into electrospun nanofibers using various combination of electrospinning parameters including the polymer solution, applied voltage and injection speed. The morphology of the fabricated scaffolds were observed using scanning electron microscope (SEM). The SEM images were analysed for the fibre diameter distribution of the scaffolds using Image Analyser. The results revealed that the 8 wt% of polymer solution, 25 kV/cm of the applied voltage and 1.5 mL/h of the injection speed was the most suitable combination. This electrospinning parameters combination fabricated nanofibrous P(3HB-co-4HB) scaffold with smooth, beadles and uniform nanofibers with small fibre diameter distribution.
    Matched MeSH terms: Polyesters
  10. A study on the effects of increment and decrement repeated fed-batch feeding of glucose on the production of poly(3-hydroxybutyrate) [P(3HB)] by a newly engineered Cupriavidus necator NSDG-GG mutant in batch fill-and-draw fermentation
    Biglari N, Orita I, Fukui T, Sudesh K
    J Biotechnol, 2020 Jan 10;307:77-86.
    PMID: 31669355 DOI: 10.1016/j.jbiotec.2019.10.013
    This study investigates the effect of strategies on poly(3-hydroxybutyrate) [P(3HB)] production in bioreactor. In the production of P(3HB), urea and glucose feeding streams were developed to characterize the fed-batch culture conditions for new Cupriavidus necator NSDG-GG mutant. Feeding urea in repeated fed-batch stage (RFB-I) at 6, and 12 h in cultivation led to insignificant kinetic effect on the cell dry mass (CDM) and P(3HB) accumulation. Feeding glucose in repeated fed-batch stage (RFB-II) demonstrated that the incremental feeding approach of glucose after urea in fill-and-draw (F/D) mode at 24, 30, 36, 42, and 48 h in fermentation increased CDM and P(3HB) concentration. In the 1st cycle in RFB-II, the cumulative CDM reached the value of 26.22 g/L and then it increased with the successive repeated fed-batches to attain biomass of 145 g/L at the end of 5th cycle of RFB-II. The final cumulative P(3HB) concentration at the end of 5th cycle of RFB-II reached 111 g/L with the overall yield of 0.50 g P(3HB) g gluc- 1; the CDM productivity from the RFB-II cycles was in the range of 0.84-1.3 g/(L·h). The RFB-II of glucose in an increment mode produced nearly 2.2 times more increase in CDM and P(3HB) productivities compared to the decrement RFB-II mode. Repeated cultivation had also the advantage of avoiding extra time required for innoculum preparation, and sterilization of bioreactor during batch, thereby it increased the overall industrial importance of the process.
    Matched MeSH terms: Polyesters
  11. Fulltext Enhanced flexibility of polylactic acid/epoxidized palm oil/pineapple fiber composites
    Nur Lisa Farhana Mohamad, Fathilah Binti Ali, Azlin Suhaida Azmi, Barre, Mohamed Soleiman, Hazleen Anuar
    Biological and Natural Resources Engineering Journal, 2020;3(1):1-7.
    MyJurnal
    The concern about our dependency on non-renewable resources and overwhelming environmental issues such as pollution caused by non-degradable packaging materials has prompted researchers to come up with alternatives to solve this problem. Thermoplastic polylactic acid (PLA) has been gaining interest due to its versatility and easy processability, thus this study was carried out to find out the properties of PLA reinforced with pineapple fibers. However, surface of the natural fibers need to be treated for better properties enhancement in the polymer matrices. Considering this, fibers were treated with 10% (w/v) concentration of potassium hydroxide (KOH) and then continued for mixing with PLA at a fixed ratio of plasticizer by using internal mixer, and then the composites were prepared into sheet via hot press. Characterization for the mechanical and morphological was conducted by using tensile testing and scanning electron microscopy, respectively. After the analysis, it is found that the surface treated pineapple fiber composite showed better elongation at break compared to untreated fiber composite. The enhance properties of PLA nanocomposites has potential to be used in various packaging materials.
    Matched MeSH terms: Polyesters
  12. Fulltext Forensic analysis of accelerant on different fabrics using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and chemometrics techniques
    Farah Izza Jais, Sharifah Mastura, Naji Arafat Mahat, Dzulkiflee Ismail, Muhammad Naeim Mohamad Asri
    Malaysian Journal of Medicine and Health Sciences, 2020;16(2):112-117.
    MyJurnal
    Introduction: Accelerants and fabrics are commonly used to spread fire attributable to their highly flammable prop- erties. Hence, having the ability to discriminate the different types of accelerants on various types of fabrics after fire and/or arson using the non-destructive Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spec- troscopy coupled with chemometric techniques appears forensically relevant. Methods: Six types of fabrics viz. cotton, wool, silk, rayon, satin, and polyester, were burnt completely with RON95 and RON97 gasoline as well as diesel. Subsequently, the samples were analyzed by ATR-FTIR spectroscopy followed by Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) for discriminating the different types of accelerants on such burned fabrics. Results: RON95 showed the fastest rate of burning on all fabric types. Results also revealed that while wool had the slowest burning rate for all the three different accelerants, polyester, cotton, and satin demon- strated the highest rate of burning in RON95, RON97, and diesel, respectively. FTIR spectra revealed the presence of alkane, alcohol, alkene, alkyne, aromatic, and amine compounds for all fabrics. The two dimensional PCA (PC1 versus PC2) demonstrated 71% of variance and it was improved by cross-validation through the three dimensional LDA technique with correct classification of 77.8%. Conclusion: ATR-FTIR spectroscopy coupled with chemometric techniques had enabled identification of the functional groups, as well as statistically supported discrimination of the different accelerants, a matter of relevance in forensic fire and arson investigations.
    Matched MeSH terms: Polyesters
  13. Fulltext Encapsulation of ginseng inside poly(lactic-co-glycolic acid)/ polyaniline microcaspsules
    Alex Zhen Kai Lo, Siti Khadijah Lukman, Syafiqah Saidin
    Malaysian Journal of Medicine and Health Sciences, 2020;16(108):1-5.
    MyJurnal
    Introduction: : Ginseng is a type of traditional medicine that has been used for thousand years to treat various dis- eases and has been proven effective in treating cardiovascular diseases. Incorporation of polyaniline (PANI) which is a type of conductive polymer together with ginseng into poly(lactic-co-glycolic acid) (PLGA) microcapsules is neces- sary for the treatment of cardiovascular diseases as the polymer will control drug release and the electroconductivity of PANI is beneficial on myocardium cells. Methods: Therefore, this project involved the encapsulation of ginseng inside PLGA/PANI microcapsules. The encapsulation of ginseng inside the microcapsules was verified through the identification of chemical composition of ginseng, PLGA and PANI using attenuated total reflectance-Fourier trans- form infrared spectroscopy (ATR-FTIR). Results: The results of scanning electron microscope (SEM) showed the formation of microspheres where the microcapsule size was decreased from 3.14±1.87 μm to 1.98±1.30 μm as the concentration of PANI increased. The distribution of microcapsules size was more homogeneous in the high con- centration of PANI as been determined through the histogram analysis. In addition, the fluorescence analysis demon- strated the efficiency of ginseng encapsulation inside PLGA/PANI microcapsules through the appearance of stained ginseng inside the microcapsules. Conclusion: As a conclusion, the ginseng was successfully encapsulated within PLGA/PANI microcapsules that will be beneficial in drug delivery application, specifically in the cardiovascular area.
    Matched MeSH terms: Polyesters
  14. Fulltext Characteristics of photo-luminescent (PL) powder applied with polyester resin as glow-in-the-dark emergency signage
    Siti Khadijah Che Osm, Munikanan, Vikneswaran, Hapsa Husen, Zuliziana Suif, Maidiana Othman, Nordila Ahmad, et al.
    ZULFAQAR International Journal of Defence Science, Engineering & Technology, 2020;3(1):32-38.
    MyJurnal
    During a disaster, the rescuer must reach the disaster area within the fastest time with the help of navigation tools. However, there might be some obstacles during the night time that make the evacuation of the victims difficult especially due to the bad weather. Hence, an attempt to produce glow-in-the-dark emergency signage to ease the evacuation process and to enhance visibility during night time is necessary. In this present study, particular emphasis is given to investigate the characteristic of photo-luminescent (PL)powder applied with polyester resin as glow-in-the-dark emergency signage. Five samples of signage were fabricated with different percentage of PL powder, i.e. 20%, 40%. 60%, 80% and 100% and mixed with 150g polyester resin. Three types of luminance test were performed to check the workability of the samples. The tests are physical appearance, one-hours illuminance test and afterglow duration tests. The result showed that the maximum lux meter reading was recorded in Sample 5 with 6 lux luminosity and provided the longest glow duration of the sample before completely off after 12-hours. Results proved that the highest percentage of the PL powder content, the longer the afterglow duration will be achieved. It also noted that the polyester resin could be a good binder of PL powder for producing the glow-in-the-dark emergency signage.
    Matched MeSH terms: Polyesters
  15. Fulltext Nanocellulose Reinforced Thermoplastic Starch (TPS), Polylactic Acid (PLA), and Polybutylene Succinate (PBS) for Food Packaging Applications
    Nazrin A, Sapuan SM, Zuhri MYM, Ilyas RA, Syafiq R, Sherwani SFK
    Front Chem, 2020;8:213.
    PMID: 32351928 DOI: 10.3389/fchem.2020.00213
    Synthetic plastics are severely detrimental to the environment because non-biodegradable plastics do not degrade for hundreds of years. Nowadays, these plastics are very commonly used for food packaging. To overcome this problem, food packaging materials should be substituted with "green" or environmentally friendly materials, normally in the form of natural fiber reinforced biopolymer composites. Thermoplastic starch (TPS), polylactic acid (PLA) and polybutylene succinate (PBS) were chosen for the substitution, because of their availability, biodegradability, and good food contact properties. Plasticizer (glycerol) was used to modify the starch, such as TPS under a heating condition, which improved its processability. TPS films are sensitive to moisture and their mechanical properties are generally not suitable for food packaging if used alone, while PLA and PBS have a low oxygen barrier but good mechanical properties and processability. In general, TPS, PLA, and PBS need to be modified for food packaging requirements. Natural fibers are often incorporated as reinforcements into TPS, PLA, and PBS to overcome their weaknesses. Natural fibers are normally used in the form of fibers, fillers, celluloses, and nanocelluloses, but the focus of this paper is on nanocellulose. Nanocellulose reinforced polymer composites demonstrate an improvement in mechanical, barrier, and thermal properties. The addition of compatibilizer as a coupling agent promotes a fine dispersion of nanocelluloses in polymer. Additionally, nanocellulose and TPS are also mixed with PLA and PBS because they are costly, despite having commendable properties. Starch and natural fibers are utilized as fillers because they are abundant, cheap and biodegradable.
    Matched MeSH terms: Polyesters
  16. Fulltext Production, purification and evaluation of biodegradation potential of PHB depolymerase of Stenotrophomonas sp. RZS7
    Sayyed RZ, Wani SJ, Alarfaj AA, Syed A, El-Enshasy HA
    PLoS One, 2020;15(1):e0220095.
    PMID: 31910206 DOI: 10.1371/journal.pone.0220095
    There are numerous reports on poly-β-hydroxybutyrate (PHB) depolymerases produced by various microorganisms isolated from various habitats, however, reports on PHB depolymerase production by an isolate from plastic rich sites scares. Although PHB has attracted commercial significance, the inefficient production and recovery methods, inefficient purification of PHB depolymerase and lack of ample knowledge on PHB degradation by PHB depolymerase have hampered its large scale commercialization. Therefore, to ensure the biodegradability of biopolymers, it becomes imperative to study the purification of the biodegrading enzyme system. We report the production, purification, and characterization of extracellular PHB depolymerase from Stenotrophomonas sp. RZS7 isolated from a dumping yard rich in plastic waste. The isolate produced extracellular PHB depolymerase in the mineral salt medium (MSM) at 30°C during 4 days of incubation under shaking. The enzyme was purified by three methods namely ammonium salt precipitation, column chromatography, and solvent purification. Among these purification methods, the enzyme was best purified by column chromatography on the Octyl-Sepharose CL-4B column giving optimum yield (0.7993 Umg-1mL-1). The molecular weight of purified PHB depolymerase was 40 kDa. Studies on the assessment of biodegradation of PHB in liquid culture medium and under natural soil conditions confirmed PHB biodegradation potential of Stenotrophomonas sp. RZS7. The results obtained in Fourier-Transform Infrared (FTIR) analysis, High-Performance Liquid Chromatography (HPLC) study and Gas Chromatography Mass-Spectrometry (GC-MS) analysis confirmed the biodegradation of PHB in liquid medium by Stenotrophomonas sp. RZS7. Changes in surface morphology of PHB film in soil burial as observed in Field Emission Scanning Electron Microscopy (FESEM) analysis confirmed the biodegradation of PHB under natural soil environment. The isolate was capable of degrading PHB and it resulted in 87.74% biodegradation. A higher rate of degradation under the natural soil condition is the result of the activity of soil microbes that complemented the biodegradation of PHB by Stenotrophomonas sp. RZS7.
    Matched MeSH terms: Polyesters/chemistry*
  17. Fulltext Kenaf Composites for Automotive Components: Enhancement in Machinability and Moldability
    Mohd Radzuan NA, Ismail NF, Fadzly Md Radzi MK, Razak ZB, Tharizi IB, Sulong AB, et al.
    Polymers (Basel), 2019 Oct 17;11(10).
    PMID: 31627431 DOI: 10.3390/polym11101707
    To date, the mechanical performance of kenaf composites is still unsatisfied in term of its mechanical performance. Therefore, research focuses on kenaf composites fabrication through the selection of polymer resin, including epoxy, polypropylene, and polylactic acid. The incorporated kenaf fibre at 10 wt % to 40 wt % loadings was conducted using injection and a compression moulding process. The compressed materials indicated high tensile strength at 240 MPa compared to inject materials (60 MPa). Significant improvement on impact strength (9 kJ/m2) was due to the unpulled-out fibre that dispersed homogenously and hence minimize the microcrack acquire. Meanwhile, high flexural strength (180 MPa) obtained by kenaf/epoxy composites due to the fibre orientate perpendicular to the loading directions, which improve its mechanical properties. The findings indicate that the kenaf fibre reinforced thermoset materials exhibit better mechanical properties as a function to the battery tray applications.
    Matched MeSH terms: Polyesters
  18. Fulltext Properties and Characterization of a PLA-Chitin-Starch Biodegradable Polymer Composite
    Olaiya NG, Surya I, Oke PK, Rizal S, Sadiku ER, Ray SS, et al.
    Polymers (Basel), 2019 Oct 11;11(10).
    PMID: 31614623 DOI: 10.3390/polym11101656
    This paper presents a comparison on the effects of blending chitin and/or starch with poly(lactic acid) (PLA). Three sets of composites (PLA-chitin, PLA-starch and PLA-chitin-starch) with 92%, 94%, 96% and 98% PLA by weight were prepared. The percentage weight (wt.%) amount of the chitin and starch incorporated ranges from 2% to 8%. The mechanical, dynamic mechanical, thermal and microstructural properties were analyzed. The results from the tensile strength, yield strength, Young's modulus, and impact showed that the PLA-chitin-starch blend has the best mechanical properties compared to PLA-chitin and PLA-starch blends. The dynamic mechanical analysis result shows a better damping property for PLA-chitin than PLA-chitin-starch and PLA-starch. On the other hand, the thermal property analysis from thermogravimetry analysis (TGA) shows no significant improvement in a specific order, but the glass transition temperature of the composite increased compared to that of neat PLA. However, the degradation process was found to start with PLA-chitin for all composites, which suggests an improvement in PLA degradation. Significantly, the morphological analysis revealed a uniform mix with an obvious blend network in the three composites. Interestingly, the network was more significant in the PLA-chitin-starch blend, which may be responsible for its significantly enhanced mechanical properties compared with PLA-chitin and PLA-starch samples.
    Matched MeSH terms: Polyesters
  19. Fulltext Experimental Investigation on Micro Milling of Polyester/Halloysite Nano-Clay Nanocomposites
    Fu G, Huo D, Shyha I, Pancholi K, Saharudin MS
    Nanomaterials (Basel), 2019 Jun 26;9(7).
    PMID: 31247963 DOI: 10.3390/nano9070917
    Efficient machining of the polyester nanocomposite components requires a better understanding of machinability characteristics of such material, which has become an urgent requirement for modern industrial production. In this research, the micro-milling of polyester/halloysite nano-clay (0.1, 0.3, 0.7, 1.0 wt%) nanocomposites were carried out and the outcomes in terms of tool wear, cutting force, the size effect, surface morphology, and surface roughness were compared with those for plain polyester. In order to accomplish the machining of the material in ductile mode, the required feed per tooth was found to be below 0.3 µm. The degree of surface breakage was also found to decrease in ductile mode. A maximum flank wear VB of 0.012 mm after removing 196 mm3 of workpiece material was measured.
    Matched MeSH terms: Polyesters
  20. Novel chitosan derivative based composite scaffolds with enhanced angiogenesis; potential candidates for healing chronic non-healing wounds
    Rizwan M, Yahya R, Hassan A, Yar M, Abd Halim AA, Rageh Al-Maleki A, et al.
    J Mater Sci Mater Med, 2019 Jun 11;30(6):72.
    PMID: 31187295 DOI: 10.1007/s10856-019-6273-3
    The success of wound healing depends upon the proper growth of vascular system in time in the damaged tissues. Poor blood supply to wounded tissues or tissue engineered grafts leads to the failure of wound healing or rejection of grafts. In present paper, we report the synthesis of novel organosoluble and pro-angiogenic chitosan derivative (CSD) by the reaction of chitosan with 1,3-dimethylbarbituric acid and triethylorthoformate (TEOF). The synthesized material was characterized by FTIR and 13C-NMR to confirm the incorporated functional groups and new covalent connectivities. Biodegradability of the synthesized chitosan derivative was tested in the presence of lysozyme and was found to be comparable with CS. The cytotoxicity and apoptosis effect of new derivative was determined against gastric adenocarcinoma (AGS) cells and was found to be non-toxic. The CSD was found to be soluble in majority of organic solvents. It was blended with polycaprolactone (PCL) to form composite scaffolds. From an ex ovo CAM assay, it was noted that CSD stimulated the angiogenesis.
    Matched MeSH terms: Polyesters/chemistry
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