Displaying publications 161 - 180 of 455 in total

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  1. Biosynthesis of P(3HB-co-3HHx) with improved molecular weights from a mixture of palm olein and fructose by Cupriavidus necator Re2058/pCB113
    Murugan P, Gan CY, Sudesh K
    Int J Biol Macromol, 2017 Sep;102:1112-1119.
    PMID: 28476592 DOI: 10.1016/j.ijbiomac.2017.05.006
    A combination of palm olein (POl) and fructose was used as carbon source for the biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] by recombinant Cupriavidus necator Re2058/pCB113. Cultures grown using 5g/L PO alone as carbon source produced cell dry weight (CDW) of 5.13g/L, 67% PHA/CDW and accumulated a copolymer containing 27mol% 3HHx in shake flask cultures. When cultures were grown in 5g/L fructose alone as the carbon source they produced CDW of 2.32g/L, 11% PHA/CDW and accumulated only poly(3-hydroxybutyrate) [P(3HB)] homopolymer. When the cells were cultured in 5g/L POl in combination with 7g/L fructose, CDW of 7.41g/L and 80% PHA/CDW was obtained with 17mol% 3HHx monomer fraction. Biosynthesis was carried out using a 13L fermenter to study the accumulation of 3HHx monomer fraction in the bacterial cells at different time point. The molecular weights of P(3HB-co-3HHx) with 4-15mol% 3HHx monomer were in the range between 5.47-6.85×105Da, which were at least two fold higher than previously reported values. Interestingly, the increase in Mwof the copolymer along with the increase in 3HHx molar fraction was observed. The viscoelastic property of the copolymer further confirmed the increase in Mw.
  2. Modification of oil palm fronds lignin by incorporation of m-cresol for improving structural and antioxidant properties
    Sa'don NA, Rahim AA, Ibrahim MNM, Brosse N, Hussin MH
    Int J Biol Macromol, 2017 Nov;104(Pt A):251-260.
    PMID: 28602987 DOI: 10.1016/j.ijbiomac.2017.06.038
    Lignin extracted from oil palm fronds (OPF) underwent chemical modification by incorporating m-cresol into the lignin matrix. This study reports on the physicochemical properties and antioxidant activity of unmodified autohydrolyzed ethanol organosolv lignin (AH EOL) and the modified autohydrolyzed ethanol organosolv lignin (AHC EOL). The lignin samples were analyzed by FTIR, 1H and 13C NMR spectroscopy, 2D NMR: HSQC spectroscopy, CHN analysis, molecular weight distribution analysis; GPC and thermal analysis; DSC and TGA. The lignin modification has reduced the hydrophobicity of its complex structure by providing better quality lignin with smaller fragments and higher solubility rate in water (DAHCEOL: 42%>DAHEOL: 25%). It was revealed that the modification of lignin has improved their structural and antioxidant properties, thus venture their possible applications.
  3. Effects of single and co-immobilization on the product specificity of type I pullulanase from Anoxybacillus sp. SK3-4
    Kahar UM, Chan KG, Sani MH, Mohd Noh NI, Goh KM
    Int J Biol Macromol, 2017 Nov;104(Pt A):322-332.
    PMID: 28610926 DOI: 10.1016/j.ijbiomac.2017.06.054
    Type I pullulanase from Anoxybacillus sp. SK3-4 (PulASK) is an unusual debranching enzyme that specifically hydrolyzes starch α-1,6 linkages at long branches producing oligosaccharides (≥G8), but is nonreactive against short branches; thus, incapable of producing reducing sugars (G1-G7). We report on the effects of both single and co-immobilization of PulASK on product specificity. PulASK was purified and immobilized through covalent attachment to three epoxides (ReliZyme EP403/M, Immobead IB-150P, and Immobead IB-150A) and an amino-epoxide (ReliZyme HFA403/M) activated supports. Following immobilization, all PulASK derivatives were active on both short and long branches in starch producing reducing sugars (predominantly maltotriose) and oligosaccharides (≥G8), respectively, a feature that is absent in the free enzyme. This study also demonstrated that co-immobilization of PulASK and α-amylase from Anoxybacillus sp. SK3-4 (TASKA) on ReliZyme HFA403/M significantly changed the product specificity compared to the free enzymes alone or individually immobilized enzymes. In conclusion, individual or co-immobilization caused changes in the product specificity, presumably due to changes in the enzyme binding pocket caused by the influence of carrier surface properties (hydrophobic or hydrophilic) and the lengths of the spacer arms.
  4. Kondogogu gum-Zn(+2)-pectinate emulgel matrices reinforced with mesoporous silica for intragastric furbiprofen delivery
    Bera H, Nadimpalli J, Kumar S, Vengala P
    Int J Biol Macromol, 2017 Nov;104(Pt A):1229-1237.
    PMID: 28688948 DOI: 10.1016/j.ijbiomac.2017.07.027
    Flurbiprofen (FLU), a non-steroidal anti-inflammatory drug, exhibits limited clinical response due to its poor physicochemical properties. This study aimed at developing reliable drug carriers for intrgastric FLU delivery with a view to improve biopharmaceutical characteristics of drug and modulate its release in a controlled manner. In this context, FLU-loaded kondogogu gum (KG)-Zn(+2)-low methoxyl (LM) pectinate emulgel matrices reinforced with calcium silicate (CS) were accomplished by ionotropic gelation technique employing zinc acetate as cross-linker and characterized for their in vitro performances. All the formulations demonstrated excellent drug encapsulation efficiency (DEE, 46-87%) and sustained drug release behavior (Q7h, 70-91%). These quality attributes were remarkably influenced by polymer-blend (LM pectin:KG) ratios, low-density oil types and CS inclusion. The drug release profile of the FLU-loaded optimized matrices (F-7) was best fitted in Korsmeyer-Peppas model with Fickian diffusion driven mechanism. It also conferred excellent in vitro gastroretention capabilities. Moreover, the drug-excipient compatibility, alteration of crystallinity and thermal behavior of drug and surface morphology of matrices were evidenced with the results of FTIR, XRD, DSC and SEM analyses, respectively. Thus, the newly developed matrices are appropriate for sustained intragastric FLU delivery and simultaneous zinc supplementation for effective inflammation and arthritis management.
  5. Effect of degree of deacetylation of chitosan on adsorption capacity and reusability of chitosan/polyvinyl alcohol/TiO2 nano composite
    Habiba U, Joo TC, Siddique TA, Salleh A, Ang BC, Afifi AM
    Int J Biol Macromol, 2017 Nov;104(Pt A):1133-1142.
    PMID: 28690164 DOI: 10.1016/j.ijbiomac.2017.07.007
    The chitosan/polyvinyl alcohol/TiO2 composite was synthesized. Two different degrees of deacetylation of chitosan were prepared by hydrolysis to compare the effectiveness of them. The composite was analyzed via field emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermal gravimetric analysis, weight loss test and adsorption study. The FTIR and XRD results proved the interaction among chitosan, PVA and TiO2 without any chemical reaction. It was found that, chitosan with higher degree of deacetylation has better stability. Furthermore, it also showed that higher DD of chitosan required less time to reach equilibrium for methyl orange. The adsorption followed the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models were fitted well for isotherm study. Adsorption capacity was higher for the composite containing chitosan with higher DD. The dye removal rate was independent of the dye's initial concentration. The adsorption capacity was increased with temperature and it was found from reusability test that the composite containing chitosan with higher DD is more reusable. It was notable that adsorption capacity was even after 15 runs. Therefore, chitosan/PVA/TiO2 composite can be a very useful material for dye removal.
  6. Effects of plasticizers on the physicochemical properties of kappa-carrageenan films extracted from Eucheuma cottonii
    Ili Balqis AM, Nor Khaizura MAR, Russly AR, Nur Hanani ZA
    Int J Biol Macromol, 2017 Oct;103:721-732.
    PMID: 28528954 DOI: 10.1016/j.ijbiomac.2017.05.105
    The physicochemical properties of κ-carrageenan films extracted from Eucheuma cottonii (E. cottonii) incorporated with different concentrations and types of plasticizers were studied. Glycerol, sorbitol, and polyethylene glycol-300 (PEG-300) in the range of 10-60% were used as plasticizers. The results showed that the thickness and moisture content (MC) of films increased significantly (p≤0.05) with the increase in plasticizer concentration. Sorbitol-plasticized films had the lowest values. Sorbitol-plasticized films have better mechanical properties and the lowest water vapor permeability (WVP), solubility and water uptake ratio (WUR) compared with glycerol and PEG-plasticized films (p≤0.05). Fourier transform infrared (FTIR) spectra showed the intermolecular reactions between κ-carrageenan and the plasticizers in the films. Scanning electron microscopy (SEM) observations indicated that sorbitol-plasticized films have a compact structure, even at the highest concentration. The melting temperature (Tm) of films decreased (p≤0.05) with an increase in the plasticizer concentration. Here, the glycerol-plasticized films had the lowest values. X-ray diffraction (XRD) showed broad and narrow peaks of the un-plasticized κ-carrageenan film at 2θ=20.0° and 2θ=8.4°, respectively. The intensity of the broad peak increased and the narrow peak disappeared as the concentration of plasticizers increased. In conclusion, films from E. cottonii successfully produced with sorbitol as the plasticizer exhibited good physical properties as packaging films.
  7. Isolation and characterization of microcrystalline cellulose from roselle fibers
    Kian LK, Jawaid M, Ariffin H, Alothman OY
    Int J Biol Macromol, 2017 Oct;103:931-940.
    PMID: 28549863 DOI: 10.1016/j.ijbiomac.2017.05.135
    In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28μm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research.
  8. Hydrogel beads bio-nanocomposite based on Kappa-Carrageenan and green synthesized silver nanoparticles for biomedical applications
    Azizi S, Mohamad R, Abdul Rahim R, Mohammadinejad R, Bin Ariff A
    Int J Biol Macromol, 2017 Nov;104(Pt A):423-431.
    PMID: 28591593 DOI: 10.1016/j.ijbiomac.2017.06.010
    This paper describes the fabrication and characterization of bio-nanocomposite hydrogel beads based on Kappa-Carrageenan (κ-Carrageenan) and bio-synthesized silver nanoparticles (Ag-NPs). The silver nanoparticles were prepared in aqueous Citrullus colocynthis seed extract as both reducing and capping agent. Cross-linked κ-Carrageenan/Ag-NPs hydrogel beads were prepared using potassium chloride as the cross-linker. The hydrogel beads were characterized using XRD and FESEM. Moreover, swelling property of the hydrogel beads was investigated. The Ag release profile of the hydrogels was obtained by fitting the experimental data to power law equation. The direct visualization of the green synthesized Ag-NPs using TEM shows particle size in the range of 23±2nm. The bio-nanocomposite hydrogels showed lesser swelling behavior in comparison with pure κ-Carrageenan hydrogel. Regardless the slow Ag release, κ-Carrageenan/Ag-NPs presented good antibacterial activities against Staphylococcus aureus, Methicilin Resistant Staphylococcus aurous, Peseudomonas aeruginosa and Escherichia coli with maximum zones of inhibition 11±2mm. Cytotoxicity study showed that the bio-nanocomposite hydrogels with non-toxic effect of concentration below 1000μg/mL have great pharmacological potential and a suitable level of safety for use in the biological systems.
  9. Characterization of bio-based plastic made from a mixture of Momordica charantia bioactive polysaccharide and choline chloride/glycerol based deep eutectic solvent
    Shafie MH, Samsudin D, Yusof R, Gan CY
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):1183-1192.
    PMID: 29944943 DOI: 10.1016/j.ijbiomac.2018.06.103
    Momordica charantia bioactive polysaccharide (MCBP) was used as an alternative source for the production of bio-based plastics (BPs) with choline chloride/glycerol-based deep eutectic solvent (DES) as a plasticizer. In this study, MCBP was initially extracted using 0.1 M citric acid at temperature 80 °C for 2 h, precipitated using ethanol, and then lyophilized. Subsequently, seven BPs were prepared: MCBP without plasticizer (MCBP), with 1% (w/w) of glycerol (MCBP-G), or with 1% (w/w) of DES at different choline chloride/glycerol molar ratios (i.e. 1.5:1, 1:1, 1:1.5, 1:2, and 1:3). The properties of these BPs were then investigated. Results showed that the tensile strains, stresses and moduli were in the range of 1.3-13.3%, 4.8-19.1 MPa and 132-2487 MPa, respectively. The melting temperatures were found in the range of 92.6-111.4 °C whereas the moisture absorptions and water vapour transmission rates (WVTR) of BPs were 1.4-6.5% and 3.6-5.4 mg/m2·s, respectively. The results also showed that these BPs exhibited bioactivities, such as microbial inhibitory activity (19.5-32.3 mm), free radical scavenging activity (10.3-18.3%) and ferric reducing antioxidant power (FRAP, 16.1-20.0 mM). In addition, it was observed that using DES as a plasticizer had improved the properties of BP, such as tensile strain (354.7-937.5%), melting temperature (4.6-20.3%), radical scavenging activity (0.6-88.6%), FRAP (0.9-18.7%) and antimicrobial activity (12.3-33.6%) compared to MCBP, due to the fact DES has caused different degrees of plasticization via hydrogen bonds and ionic bonds with the polymer chains, and induced a lower pH condition. Therefore, it was suggested that these BPs with DES could contribute to food preservation properties.
  10. Magnetic nanocellulose alginate hydrogel beads as potential drug delivery system
    Supramaniam J, Adnan R, Mohd Kaus NH, Bushra R
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):640-648.
    PMID: 29894784 DOI: 10.1016/j.ijbiomac.2018.06.043
    Magnetic nanocellulose alginate hydrogel beads are produced from the assembly of alginate and magnetic nanocellulose (m-CNCs) as a potential drug delivery system. The m-CNCs were synthesized from cellulose nanocrystals (CNCs) that were isolated from rice husks (RH) by co-precipitation method and were incorporated into alginate-based hydrogel beads with the aim of enhancing mechanical strength and regulating drug release behavior. Ibuprofen was chosen as a model drug. The prepared CNCs, m-CNCs and the alginate hydrogel beads were characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer studies (VSM). Besides the magnetic property, the presence of m-CNCs increased the integrity of the alginate hydrogel beads and the swelling percentage. The drug release study exhibited a controlled release profiles and based on the drug release data, the drug release mechanism was analyzed and discussed based on mathematical models such as Korsmeyer-Peppas and Peppas-Sahlin.
  11. Genetic polymorphisms of human transcription factor-7 like 2 (TCF7L2), β-defensin (DEFB1) and CD14 genes in nephrolithiasis patients
    Mehdi WA, Mehde AA, Raus RA, Yusof F, Abidin ZAZ, Ghazali H, et al.
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):610-616.
    PMID: 29959006 DOI: 10.1016/j.ijbiomac.2018.06.113
    BACKGROUND: It is assumed that genetic factors play crucial role in nephrolithiasis. The present study was conducted to explore the role of Human Transcription Factor-7 like-2 (TCF7L2) β-defensin (DEFB1) and CD14 gene polymorphism in development and progression of nephrolithiasis.

    METHODS: The genotypes of TCF7L2, DEFB1 and CD14 polymorphism were determined in 240 nephrolithiasis patients and 240 healthy controls by restriction digestion method of PCR. The levels of serum TCF7L2, DEFB1, CD14, uric acid and other biochemical parameters were measured both in nephrolithiasis patients and healthy control.

    RESULTS: The patients and control groups showed 30% and 50% 1654 AA DEFB1 genotype respectively. The Allele frequency in case of patient's group was 63.67% while in control group it was 36.33%. The mean serum DEFB1 levels of the patients and control groups attained were 115.66 and 239.43 pg/mL respectively. The allele frequency of TCF7L2 in patients and controls were 44.17% and 70.0% for C-allele, 55.83% and 30.00% for T-allele respectively. The mean of serum TCF7L2 levels were significantly decreased in patients compared to control group.

    CONCLUSIONS: The present findings are first of its class that validates a considerable connection of DEFB1 and TCF7L2 gene polymorphisms with nephrolithiasis and could probably act as indicators to estimate the risk associated to nephrolithiasis.

  12. Facile synthesis and characterization of tailor-made pectin-gellan gum-bionanofiller composites as intragastric drug delivery shuttles
    Bera H, Kumar S, Maiti S
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):149-159.
    PMID: 29932998 DOI: 10.1016/j.ijbiomac.2018.06.085
    Olive oil-entrapped diethanolamine-modified high-methoxyl pectin (DMP)-gellan gum (GG)-bionanofiller composites were developed for controlled intragastric delivery of metformin HCl (MFM). DMP had a degree of amidation of 48.7% and was characterized further by FTIR, XRD and DSC analyses. MFM-loaded composites were subsequently accomplished by green synthesis via ionotropic gelation technique using zinc acetate as cross-linker. The thermal, X-ray and infrared analyses suggested an environment in the composites compatible with the drug, except certain degree of attenuation in drug's crystallinity. Scanning electron microscopy revealed almost spherical shape of the composites. Depending upon the mass ratios of GG:DMP, types of nanofiller (neusilin/bentonite/Florite) and oil inclusion, the composites exhibited variable drug encapsulation efficiency (DEE, 50-85%) and extended drug release behaviours (Q8h, 69-94%) in acetate buffer (pH 4.5). The optimized oil-entrapped Florite R NF/GG: DMP (1:1) composites eluted MFM via case-II transport mechanism and its drug release data was best fitted in zero-order kinetic model. The optimized formulation demonstrated excellent gastroretentive properties and substantial hypoglycemic effect in streptozotocin-induced diabetic rats. These novel hybrid matrices were thus found suitable for controlled intragastric delivery of MFM for the management of type 2 diabetes.
  13. Influence of a nonionic surfactant on curcumin delivery of nanocellulose reinforced chitosan hydrogel
    Sampath Udeni Gunathilake TM, Ching YC, Chuah CH, Illias HA, Ching KY, Singh R, et al.
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):1055-1064.
    PMID: 30001596 DOI: 10.1016/j.ijbiomac.2018.06.147
    Nanocellulose reinforced chitosan hydrogel was synthesized using chemical crosslinking method for the delivery of curcumin which is a poorly water-soluble drug. Curcumin extracted from the dried rhizomes of Curcuma longa was incorporated to the hydrogel via in situ loading method. A nonionic surfactant (Tween 20) was incorporated into the hydrogel to improve the solubility of curcumin. After the gas foaming process, hydrogel showed large interconnected pore structures. The release studies in gastric medium showed that the cumulative release of curcumin increased from 0.21% ± 0.02% to 54.85% ± 0.77% with the increasing of Tween 20 concentration from 0% to 30% (w/v) after 7.5 h. However, the entrapment efficiency percentage decreased with the addition of Tween 20. The gas foamed hydrogel showed higher initial burst release within the first 120 min compared to hydrogel formed at atmospheric condition. The solubility of curcumin would increase to 3.014 ± 0.041 mg/mL when the Tween 20 concentration increased to 3.2% (w/v) in simulated gastric medium. UV-visible spectra revealed that the drug retained its chemical activity after in vitro release. From these findings, it is believed that the nonionic surfactant incorporated chitosan/nanocellulose hydrogel can provide a platform to overcome current problems associated with curcumin delivery.
  14. In vitro neuroprotective effects of naringenin nanoemulsion against β-amyloid toxicity through the regulation of amyloidogenesis and tau phosphorylation
    Md S, Gan SY, Haw YH, Ho CL, Wong S, Choudhury H
    Int J Biol Macromol, 2018 Oct 15;118(Pt A):1211-1219.
    PMID: 30001606 DOI: 10.1016/j.ijbiomac.2018.06.190
    Alzheimer's disease (AD) is an increasingly prevalent neurological disorder of the central nervous system. There is growing evidence that amyloidogenesis is a pathological hallmark for AD; this leads to the formation of senile plaques. Naringenin is a bioflavonoid which has neuroprotective effects through its antioxidant and anti-inflammatory properties. However, its clinical usage is limited due to its inefficient transport across biological membranes. In the present study, a naringenin nanoemulsion was prepared and its neuroprotective effects were tested against β-amyloid induced neurotoxicity in a human neuroblastoma cell line (SH-SY5Y). The optimised, naringenin-loaded nanoemulsion formulation had a droplet size of 113.83 ± 3.35 nm and around 50 nm, as assessed respectively by photon correlation spectroscopy and transmission electron microscopy. The preparation showed a low polydispersity index (0.312 ± 0.003), a high zeta potential (12.4 ± 1.05) and a high percentage transmittance (97.01%). The neuroprotective activity of naringenin nanoemulsions was determined by assessing their ability to protect SH-SY5Y neuroblastoma cells against the neurotoxic effect of beta amyloid (Aβ). Aβ-induced production of reactive oxygen species (ROS), amyloid precursor protein (APP), β-secretase (BACE), total tau and phosphorylated tau (pT231) was also determined. The naringenin loaded nanoemulsion significantly alleviated the direct neurotoxic effects of Aβ on SH-SY5Y cells; this was associated with a down-regulation of APP and BACE expression, indicating reduced amyloidogenesis. Furthermore, it decreased the levels of phosphorylated tau in SH-SY5Y cells exposed to Aβ. These results suggest that a naringenin-loaded nanoemulsion could be a promising agent for the treatment of Alzheimer's disease.
  15. Chemically crosslinked hydrogel and its driving force towards superabsorbent behaviour
    Salleh KM, Zakaria S, Sajab MS, Gan S, Chia CH, Jaafar SNS, et al.
    Int J Biol Macromol, 2018 Oct 15;118(Pt B):1422-1430.
    PMID: 29964115 DOI: 10.1016/j.ijbiomac.2018.06.159
    Dissolved oil palm empty fruit bunch (EFB) cellulose in NaOH/urea solvent was mixed with sodium carboxymethylcellulose (NaCMC) to form a green regenerated superabsorbent hydrogel. The effect of concentration of epichlorohydrin (ECH) as the crosslinker on the formation, physical, and chemical properties of hydrogel was studied. Rapid formation and higher gel content of hydrogel were observed at 10% concentration of ECH. The superabsorbent hydrogel was successfully fabricated in this study with the swelling ability >100,000%. Hydrogel with higher concentration of ECH showed opposite trend by having higher superabsorbent property than that of lower concentration. The covalent bond of COC was observed with Attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy to confirm the occurrence of crosslinking. The physical and chemical properties of hydrogel were affected by swelling phenomenon. Hydrogel with higher degree of swelling exhibited lower moisture retention and higher transparency. Moreover, the weight of the superabsorbent hydrogel increased with the decrement of pH value of external media (distilled water). This study provided substantial information on the effect of different percentage of ECH as crosslinker on hydrogel basic properties. Furthermore, this study affords correlation of many essential driving forces that affected hydrogel superabsorbent property.
  16. Silver nanoparticle functionalized CS-g-(CA-MA-PZA) carrier for sustainable anti-tuberculosis drug delivery
    Amarnath Praphakar R, Jeyaraj M, Ahmed M, Suresh Kumar S, Rajan M
    Int J Biol Macromol, 2018 Oct 15;118(Pt B):1627-1638.
    PMID: 29981824 DOI: 10.1016/j.ijbiomac.2018.07.008
    Recently, drug functionalized biodegradable polymers have been appreciated to be imperative to fabricate multi-drug delivery nanosystems for sustainable drug release. In this work, amphiphilic chitosan-grafted-(cetyl alcohol-maleic anhydride-pyrazinamide) (CS-g-(CA-MA-PZA)) was synthesized by multi-step reactions. The incorporation of rifampicin (RF) and entrapment of silver nanoparticles (Ag NPs) on CS-g-(CA-MA-PZA) polymer was carried out by dialysis technique. From the FT-IR experiment, the polymer modification, incorporation of drugs and the entrapment of Ag NPs on micelles were confirmed. The surface morphology of Ag NPs, polymeric system and drug loaded micelles was described by SEM, TEM and AFM techniques. In addition, the controlled release behaviour of CS-g-(CA-MA-PZA) micelles was studied by UV-Vis spectroscopy. In vitro cell viability, cell apoptosis and cellular uptake experiments shows that multi-drug delivery system could enhance the biocompatibility and higher the cytotoxicity effect on the cells. Since the prepared amphiphilic polymeric micelles exhibit spotty features and the system is a promising strategy for a novel candidate for immediate therapeutically effects for alveolar macrophages.
  17. Modelling of polyhydroxyalkanoate synthase from Aquitalea sp. USM4 suggests a novel mechanism for polymer elongation
    Teh AH, Chiam NC, Furusawa G, Sudesh K
    Int J Biol Macromol, 2018 Nov;119:438-445.
    PMID: 30048726 DOI: 10.1016/j.ijbiomac.2018.07.147
    Polyhydroxyalkanoate (PHA) synthase, PhaC, is a key enzyme in the biosynthesis of PHA, a type of bioplastics with huge potential to replace petroleum-based plastics. While two structures have been determined, the exact mechanism remains unclear partly due to the absence of a tunnel for product passage. A model of the class I PhaC from Aquitalea sp. USM4, characterised with Km of 394 μM and kcat of 476 s-1 on 3-(R)-hydroxybutyryl-CoA, revealed a three-branched channel at the dimeric interface. Two of them are opened to the solvent and are expected to serve as the putative routes for substrate entrance and product exit, while the third is elongated in the class II PhaC1 model from Pseudomonas aeruginosa, indicating a role in accommodating the hydroxyalkanoate (HA) moiety of a HA-CoA substrate. Docking of the two tetrahedral intermediates, formed during the transfer of the growing PHA chain from the catalytic Cys to a new molecule of substrate and back to Cys, suggests a common elongation mechanism requiring the HA moiety of the ligand to rotate ~180°. Substrate specificity is determined in part by a bulky Phe/Tyr/Trp residue in the third branch in class I, which is conserved as Ala in class II to create room for longer substrates.
  18. Cross-linked beads of activated oil palm ash zeolite/chitosan composite as a bio-adsorbent for the removal of methylene blue and acid blue 29 dyes
    Khanday WA, Asif M, Hameed BH
    Int J Biol Macromol, 2017 Feb;95:895-902.
    PMID: 27789331 DOI: 10.1016/j.ijbiomac.2016.10.075
    Cross-linked beads of activated oil palm ash zeolite/chitosan (Z-AC/C) composite were prepared through the hydrothermal treatment of NaOH activated oil palm ash followed by beading with chitosan. The effects of initial dye concentration (50-400mg/L), temperature (30°C-50°C) and pH (3-13) on batch adsorption of methylene blue (MB) and acid blue 29 (AB29) were studied. Adsorption of both dyes was better described by Pseudo-second-order kinetics and Freundlich isotherm model. The maximum adsorption capacities of Z-AC/C were 151.51, 169.49, and 199.20mg/g for MB and 212.76, 238.09, and 270.27mg/g for AB29 at 30°C, 40°C, and 50°C, respectively.
  19. Optimization, characterization, and in vitro assessment of alginate-pectin ionic cross-linked hydrogel film for wound dressing applications
    Rezvanian M, Ahmad N, Mohd Amin MC, Ng SF
    Int J Biol Macromol, 2017 Apr;97:131-140.
    PMID: 28064048 DOI: 10.1016/j.ijbiomac.2016.12.079
    Natural polymer-based hydrogel films have great potential for biomedical applications and are good candidates for wound dressings. In this study, we aimed to develop simvastatin-loaded crosslinked alginate-pectin hydrogel films by ionic crosslinking to improve the mechanical characteristics, wound fluid uptake and drug release behavior. Alginate-pectin hydrocolloid films were chemically crosslinked by immersing in different concentrations of CaCl2 (0.5-3% w/v) for 2-20min. The degree of crosslinking was influenced by both contact time and CaCl2 concentration. The optimized conditions for crosslinking were 0.5% and 1% (CaCl2) for 2min. The optimized hydrogel films were then characterized for their physical, mechanical, morphological, thermal, in vitro drug release, and cytocompatibility profiles. Crosslinking improved the mechanical profile and wound fluid uptake capacity of dressings. The hydrogel films were able to maintain their physical integrity during use, and the best results were obtained with the film in which the extent of crosslinking was low (0.5%). Thermal analysis confirmed that the crosslinking process enhanced the thermal stability of hydrogel films. Sustained, slow release of simvastatin was obtained from the crosslinked films and in vitro cytotoxicity assay demonstrated that the hydrogel films were non-toxic.
  20. Mechanical, morphological and structural properties of cellulose nanofibers reinforced epoxy composites
    Saba N, Mohammad F, Pervaiz M, Jawaid M, Alothman OY, Sain M
    Int J Biol Macromol, 2017 Apr;97:190-200.
    PMID: 28082223 DOI: 10.1016/j.ijbiomac.2017.01.029
    Present study, deals about isolation and characterization of cellulose nanofibers (CNFs) from the Northern Bleached Softwood Kraft (NBSK) pulp, fabrication by hand lay-up technique and characterization of fabricated epoxy nanocomposites at different filler loadings (0.5%, 0.75%, 1% by wt.). The effect of CNFs loading on mechanical (tensile, impact and flexural), morphological (scanning electron microscope and transmission electron microscope) and structural (XRD and FTIR) properties of epoxy composites were investigated. FTIR analysis confirms the introduction of CNFs into the epoxy matrix while no considerable change in the crystallinity and diffraction peaks of epoxy composites were observed by the XRD patterns. Additions of CNFs considerably enhance the mechanical properties of epoxy composites but a remarkable improvement is observed for 0.75% CNFs as compared to the rest epoxy nanocomposites. In addition, the electron micrographs revealed the perfect distribution and dispersion of CNFs in the epoxy matrix for the 0.75% CNFs/epoxy nanocomposites, while the existence of voids and agglomerations were observed beyond 0.75% CNFs filler loadings. Overall results analysis clearly revealed that the 0.75% CNFs filler loading is best and effective with respect to rest to enhance the mechanical and structural properties of the epoxy composites.
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