Publications by authors named "Junaid Haider"

14 Publications

  • Page 1 of 1

Dye degradation, antibacterial and in-silico analysis of Mg/cellulose-doped ZnO nanoparticles.

Int J Biol Macromol 2021 Jun 19;185:153-164. Epub 2021 Jun 19.

Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, 14 Ali Road, Lahore, Pakistan.

Various concentrations of Mg into fixed amount of cellulose nanocrystals (CNC)-doped ZnO were synthesized using facile chemical precipitation. The aim of present study is to remove dye degradation of methylene blue (MB) and bactericidal behavior with synthesized product. Phase constitution, functional group analysis, optical behavior, elemental composition, morphology and microstructure were examined using XRD, FTIR, UV-Vis spectrophotometer, EDS and HR-TEM. Highly efficient photocatalytic performance was observed in basic medium (98%) relative to neutral (65%), and acidic (83%) was observed upon Mg and CNC co-doping. Significant bactericidal activity of doped ZnO nanoparticles depicted inhibition zones for G -ve and +ve bacteria ranging (2.20 - 4.25 mm) and (5.80-7.25 mm) for E. coli and (1.05 - 2.75 mm) and (2.80 - 4.75 mm) for S. aureus at low and high doses, respectively. Overall, doped nanostructures showed significant (P < 0.05) bactericidal efficacy against G +ve relative to G -ve. Furthermore, the molecular docking studies were employed to rationalize possible mechanism behind these in vitro bactericidal activities. In silico findings suggested CNC doped ZnO nanocomposites as possible inhibitors of β-lactamase (Binding score: -7.936 kcal/mol), DHFR (Binding score: -5.691 kcal/mol) and FabI (Binding score: -8.673 kcal/mol).
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http://dx.doi.org/10.1016/j.ijbiomac.2021.06.101DOI Listing
June 2021

Development of Multi-concentration Cu:Ag Bimetallic Nanoparticles as a Promising Bactericidal for Antibiotic-Resistant Bacteria as Evaluated with Molecular Docking Study.

Nanoscale Res Lett 2021 May 22;16(1):91. Epub 2021 May 22.

Department of Chemistry, Quaid-I-Azam University, Islamabad, 45320, Pakistan.

The present study is concerned with evaluating the influence of various concentrations of Ag within Cu:Ag bimetallic nanoparticles developed for use as a promising anti-bacterial agent against antibiotic-resistant bacteria. Here, Cu:Ag bimetallic nanoparticles with various concentration ratios (2.5, 5.0, 7.5, and 10 wt%) of Ag in fixed amount of Cu labeled as 1:0.025, 1:0.050, 1:0.075, and 1:0.1 were synthesized using co-precipitation method with ammonium hydroxide and deionized water as solvent, polyvinyl pyrrolidone as a capping agent, and sodium borohydride and ascorbic acid as reducing agents. These formulated products were characterized through a variety of techniques. XRD confirmed phase purity and detected the presence of distinct fcc structures belonging to Cu and Ag phases. FTIR spectroscopy confirmed the presence of vibrational modes corresponding to various functional groups and recorded characteristic peak emanating from the bimetallic. UV-visible spectroscopy revealed reduction in band gap with increasing Ag content. SEM and HR-TEM micrographs revealed spherical morphology of Ag-doped Cu bimetallic with small and large scale agglomerations. The samples exhibited varying dimensions and interlayer spacing. Bactericidal action of synthesized Cu:Ag bimetallic NPs depicted statistically significant (P < 0.05) inhibition zones recorded for various concentrations of Ag dopant against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Acinetobacter baumannii (A. baumannii) ranging from (0.85-2.8 mm), (0.55-1.95 mm) and (0.65-1.85 mm), respectively. Broadly, Cu:Ag bimetallic NPs were found to be more potent against gram-positive compared with gram-negative. Molecular docking study of Ag-Cu bimetallic NPs was performed against β-lactamase which is a key enzyme of cell wall biosynthetic pathway from both S. aureus (Binding score: - 4.981 kcal/mol) and A. bauminnii (Binding score: - 4.013 kcal/mol). Similarly, binding interaction analysis against FabI belonging to fatty acid biosynthetic pathway from A. bauminnii (Binding score: - 3.385 kcal/mol) and S. aureus (Binding score: - 3.012 kcal/mol) along with FabH from E. coli (Binding score: - 4.372 kcal/mol) was undertaken. These theoretical computations indicate Cu-Ag bimetallic NPs as possible inhibitor of selected enzymes. It is suggested that exploring in vitro inhibition potential of these materials may open new avenues for antibiotic discovery.
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http://dx.doi.org/10.1186/s11671-021-03547-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8141091PMC
May 2021

Impact of Bi Doping into Boron Nitride Nanosheets on Electronic and Optical Properties Using Theoretical Calculations and Experiments.

Nanoscale Res Lett 2021 May 12;16(1):82. Epub 2021 May 12.

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.
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http://dx.doi.org/10.1186/s11671-021-03542-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8116421PMC
May 2021

Doping of Mg on ZnO Nanorods Demonstrated Improved Photocatalytic Degradation and Antimicrobial Potential with Molecular Docking Analysis.

Nanoscale Res Lett 2021 May 1;16(1):78. Epub 2021 May 1.

Physics Department, Lahore Garrison University, Lahore, Punjab, 54000, Pakistan.

Various concentrations of Mg-doped ZnO nanorods (NRs) were prepared using co-precipitation technique. The objective of this study was to improve the photocatalytic properties of ZnO. The effect of Mg doping on the structure, phase constitution, functional groups presence, optical properties, elemental composition, surface morphology and microstructure of ZnO was evaluated with XRD, FTIR, UV-Vis spectrophotometer, EDS, and HR-TEM, respectively. Optical absorption spectra obtained from the prepared samples showed evidence of blueshift upon doping. XRD results revealed hexagonal wurtzite phase of nanocomposite with a gradual decrease in crystallite size with Mg addition. PL spectroscopy showed trapping efficiency and migration of charge carriers with electron-hole recombination behavior, while HR-TEM estimated interlayer d-spacing. The presence of chemical bonding, vibration modes and functional groups at the interface of ZnO was revealed by FTIR and Raman spectra. In this study, photocatalytic, sonocatalytic and sonophotocatalytic performance of prepared NRs was systematically investigated by degrading a mixture of methylene blue and ciprofloxacin (MBCF). Experimental results suggested that improved degradation performance was shown by Mg-doped ZnO NRs. We believe that the product synthesized in this study will prove to be a beneficial and promising photocatalyst for wastewater treatment. Conclusively, Mg-doped ZnO exhibited substantial (p < 0.05) efficacy against gram-negative (G-ve) as compared to gram-positive (G+ve) bacteria. In silico molecular docking studies of Mg-doped ZnO NRs against DHFR (binding score: - 7.518 kcal/mol), DHPS (binding score: - 6.973 kcal/mol) and FabH (- 6.548 kcal/mol) of E. coli predicted inhibition of given enzymes as possible mechanism behind their bactericidal activity.
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http://dx.doi.org/10.1186/s11671-021-03537-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8088420PMC
May 2021

Liquid-phase exfoliated MoS nanosheets doped with -type transition metals: a comparative analysis of photocatalytic and antimicrobial potential combined with density functional theory.

Dalton Trans 2021 May;50(19):6598-6619

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

MoS2 nanosheets were developed by undertaking the liquid-phase exfoliation of bulk counterparts. In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (i.e., Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals (TM). X-ray diffraction detected the existence of 2H-phase by mirroring its reflection at 2θ ∼ 14°, while the peak distribution revealed the degree of exfoliation in samples. Low PL intensities indicated a lower recombination of electron-hole pairs, as corroborated by a high degree of photocatalytic action. Raman analysis was undertaken to identify molecular vibrations. The A1g mode in Raman spectra consistently showed a blueshift in all samples and the E12g mode was only slightly affected, which is evidence of the p-type doping in the MoS2 nanosheets. In the XPS spectrum, two characteristic peaks of Mo 3d appeared at 229.87 and 233.03 eV assigned to Mo-3d5/2 and Mo-3d3/2, respectively. Furthermore, a microstructural examination with HR-TEM and FESEM divulged a thin-layered structure of MoS2 consisting of flat, gently curved or twisted nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded methylene blue (MB) concentrations of up to 94 percent (for Ag-MoS2). The synergistic effect of doped MoS2 nanosheets against S. aureus in comparison to E. coli bacteria was also evaluated. The efficacy % age improved from (0-31.7%) and (23.5-55.2%) against E. coli, and (0-34.2%) and (8.3-69.23%) against S. aureus. Moreover, results from first principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. Theoretical calculations confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the band gap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS2 monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character.
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http://dx.doi.org/10.1039/d1dt00236hDOI Listing
May 2021

Photocatalytic, Bactericidal and Molecular Docking Analysis of Annealed Tin Oxide Nanostructures.

Nanoscale Res Lett 2021 Feb 10;16(1):33. Epub 2021 Feb 10.

Physics Department, Lahore Garrison University, Lahore, 54000, Pakistan.

Nanosized tin oxide was fabricated with a simple and cost-effective precipitation technique and was analyzed by performing x-ray powder diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, high-resolution transmission electron (HR-TEM) microscopy, energy-dispersive x-ray (EDX) and UV-Vis spectroscopy. The XRD results revealed that tin oxide particles possessed typical orthorhombic structure and exhibited improved crystallinity with annealing. Calcination at 250 °C produced predominantly orthorhombic SnO which transformed to SnO at higher temperatures of 500 and 750 °C. HRTEM and FESEM images showed existence of agglomeration within the particles of tin oxide. The absorption was found to increase up to a certain annealing temperature followed by a decrease, which was recorded via UV-Vis spectroscopy. The effect of annealing temperature on dye decomposition behavior of synthesized photocatalysts was studied. It was noted that annealing temperature affects the size of synthesized particles, band gap width and photoactivity of tin oxide. The sample prepared at 500 °C followed first-order kinetics and exhibited maximum photocatalytic reactivity toward methylene blue. The experimental results obtained from the present study indicate that SnO is a promising and beneficial catalyst to remove contaminants from wastewater and environment. The antimicrobial evaluation of SnO annealed at 500 °C against selected targets such as E. coli and S. aureus depicted significant inhibition zones in comparison with 250 and 750 °C samples. Furthermore, molecular docking predictions of SnO nanoparticles (NPs) were performed against active pocket of β-lactamase and DNA gyrase enzyme belonging to cell wall and nucleic acid biosynthetic pathway, respectively. The fabricated NPs showed good binding score against β-lactamase of both E. coli (- 5.71 kcal/mol) and S. aureus (- 11.83 kcal/mol) alongside DNA gyrase (- 9.57 kcal/mol; E. coli and - 8.61 kcal/mol; S. aureus). These in silico predictions suggested SnO NPs as potential inhibitors for selected protein targets and will facilitate to have a clear understanding of their mechanism of action that may contribute toward new antibiotics discovery.
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http://dx.doi.org/10.1186/s11671-021-03495-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7876220PMC
February 2021

Silver Decorated 2D Nanosheets of GO and MoS2 serve as Nanocatalyst for Water Treatment and Antimicrobial Applications as ascertained with Molecular Docking Evaluation.

Nanotechnology 2021 Feb 8. Epub 2021 Feb 8.

Physics, Government College University Lahore, Katchery Road, Lahore, Punjab, 54000, PAKISTAN.

Two-dimensional (2D) nanosheets doped with silver nanoparticles (AgNPs) have found significant antibacterial applications in industry. In this work, synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) was realized through a modified Hummers route. Different concentrations (5 & 10 wt.%) of Ag were doped in MoS2 and rGO using a hydrothermal approach. Synthesized Ag-MoS2 and Ag-rGO were evaluated through XRD that confirmed the hexagonal structure of MoS2 along with the transformation of GO to Ag-rGO as indicated by a shift in XRD peaks. FTIR confirmed the presence of Mo-O bonding vibrations, and S=O functional groups present in the prepared samples. Morphological information of GO and formation of MoS2 nanopetals were verified through FESEM, while spherical morphology, interlayer spacing, and homogeneous distribution of AgNPs were scrutinized through HR-TEM. Raman analysis was employed to probe any evidence regarding defect densities of GO. Optical properties of GO, MoS2, Ag-rGO, and Ag-MoS2 were visualized through UV-Vis & PL spectroscopy. Prepared products were employed as nanocatalysts to purify industrial wastewater, while degradation of undoped and doped samples was inspected using UV-Vis spectroscopy. Experimental results revealed that the photocatalytic response of Ag-rGO and Ag-MoS2 enhanced upon doping. Besides, the nanocatalyst (Ag-MoS2 & Ag-rGO) exhibited an excellent antibacterial activity towards S. aureus gram positive (G+) and E. coli gram negative (G-). To rationalize biocidal mechanism of Ag-doped MoS2 NPs and Ag-rGO, in silico molecular docking study was employed for two enzymes (i.e. β-lactamase & ddlB) from cell wall biosynthetic pathway and FabI from fatty acid biosynthetic pathway belonging to S. aureus. The present study provides evidence for the development of cost-effective and environmental-friendly products that could receive favorable recommendation for use in industrial and biomedical applications.
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http://dx.doi.org/10.1088/1361-6528/abe43cDOI Listing
February 2021

Engineered LPMO Significantly Boosting Cellulase-Catalyzed Depolymerization of Cellulose.

J Agric Food Chem 2020 Dec 8;68(51):15257-15266. Epub 2020 Dec 8.

Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.

Lytic polysaccharide monooxygenases (LPMOs) play a crucial role in the enzymatic depolymerization of cellulose through oxidative cleavage of the glycosidic bond in the highly recalcitrant crystalline cellulose region. Improving the activity of LPMOs is of considerable importance for second-generation biorefinery. In this study, we identified a beneficial amino acid substitution (N526S) located in the cellulose binding module (CBM) of LPMO10 (LPMO of ) using directed evolution. The improved variant LPMO10 M1 (N526S) exhibits 2.1-fold higher activity for the HO production, 2.7-fold higher oxidation activity, and 1.9-fold higher binding capacity toward cellulose compared with those of the wild type (WT). Furthermore, M1 shows 2.1-fold higher activity for degradation of crystalline cellulose in synergy with cellulase, compared to the WT. Structural analysis through molecular modeling and molecular dynamics (MD) simulation revealed that the substitution N526S located in the CBM likely stabilizes the cellulose binding surface and enhances the binding capacity of LPMO10 to cellulose, thereby enhancing enzyme activity. These findings demonstrate the important role of the CBM in the catalytic function of LPMO.
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http://dx.doi.org/10.1021/acs.jafc.0c05979DOI Listing
December 2020

Potential applications of hydrophobically modified inulin as an active ingredient in functional foods and drugs - A review.

Carbohydr Polym 2021 Jan 6;252:117176. Epub 2020 Oct 6.

Department of Food Science and Technology, MNS-University of Agriculture, Multan, Pakistan. Electronic address:

Over the past few years, hydrophobically modified inulin (HMI) has gained considerable attention due to its multitudinous features. The targeted release of drugs remains a subject of research interest. Moreover, it is important to explore the properties of short-chain fatty acids (SCFAs) inulin esters because they are less studied. Additionally, HMI has been used to stabilize various dispersion formulations, which have been observed to be safe because inulin is generally recognized as safe (GRAS). However, the results regarding HMI-based dispersion products are dispersed throughout the literature. This comprehensive review is discussed the possible limitations regarding SCFAs inulin esters, real food dispersion formulations, and HMI drugs. The results revealed that SCFAs inulin esters can regulate the human gut microbiota and increase the biological half-life of SCFAs in the human body. This comprehensive review discusses the versatility of HMI as a promising excipient for the production of hydrophobic drugs.
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http://dx.doi.org/10.1016/j.carbpol.2020.117176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536552PMC
January 2021

Photocatalytic, dye degradation, and bactericidal behavior of Cu-doped ZnO nanorods and their molecular docking analysis.

Dalton Trans 2020 Jun;49(24):8314-8330

Solar Cell Applications Research Lab, Department of Physics, Government College University Lahore, 54000, Punjab, Pakistan.

Nanostructures of Cu-doped ZnO (Cu:ZnO) were prepared with the chemical precipitation technique with an aim to enhance the photocatalytic and antibacterial properties of ZnO. Phase constitution, the presence of functional groups, optical properties, elemental composition, surface morphology and microstructure were evaluated using an X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HR-TEM), respectively. Emission spectra were obtained with a photoluminescence (PL) spectroscope whereas interlayer d-spacing was estimated through HR-TEM. ZnO consisted of a hexagonal wurtzite structure. The crystallinity of the sample was observed to increase with increasing doping concentration. The addition of Cu to ZnO served to transform nanoclusters into nanorods as revealed during SEM analysis. Catalytic activity enhanced due to the formation of nanorods, and UV-Vis absorption spectra showed that methylene blue (MB) degraded more efficiently with ZnO nanoclusters compared to the NaBH4 reagent. In addition, the doped NPs showed enhanced bacterial efficiency for G +ve. Finally, a molecular docking study was undertaken to highlight the importance of the binding interactions of the Cu-doped ZnO nanorods with β-lactamase and beta-ketoacyl-acyl carrier protein synthase III (FabH) as possible enzyme targets. This research indicates that Cu-doped Zn nanorods are a highly efficient photocatalyst and can be aptly employed for wastewater treatment and antibacterial applications.
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http://dx.doi.org/10.1039/d0dt01397hDOI Listing
June 2020

Green Synthesized Phytochemically (Zingiber officinale and Allium sativum) Reduced Nickel Oxide Nanoparticles Confirmed Bactericidal and Catalytic Potential.

Nanoscale Res Lett 2020 Mar 2;15(1):50. Epub 2020 Mar 2.

Solar Cell Applications Research Lab, Department of Physics, Government College University, Lahore, Punjab, 54000, Pakistan.

Phyto-synthesized nanoparticles (NPs) having reduced chemical toxicity have been focused globally and become essential component of nanotechnology recently. We prepared green phytochemically (ginger and garlic) reduced NiO-NPs to replace synthetic bactericidal and catalytic agent in textile industry. NPs were characterized using ultra-violet visible spectroscopy (UV-Vis), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The synthesis of NPs was confirmed by XRD and UV-Vis having strong absorption at 350 nm with size ranged between 16-52 nm for ginger and 11-59 nm for garlic. Scanning and transmission electron microscopy confirmed pleomorphism with cubic- and more spherical-shaped NPs. Moreover, exact quantities of garlic and ginger extracts (1:3.6 ml) incorporated to synthesize NiO-NPs have been successfully confirmed by FTIR. Phytochemically reduced NPs by garlic presented enhanced bactericidal activity against multiple drug-resistant Staphylococcus aureus at increasing concentrations (0.5, 1.0 mg/50 μl) and also degraded methylene blue (MB) dye efficiently. Conclusively, green synthesized NiO-NPs are impending activists to resolve drug resistance as well as environment friendly catalytic agent that may be opted at industrial scale.
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http://dx.doi.org/10.1186/s11671-020-3283-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7052104PMC
March 2020

Purification of 2,3-butanediol from fermentation broth: process development and techno-economic analysis.

Biotechnol Biofuels 2018 25;11:18. Epub 2018 Jan 25.

School of Chemical Engineering, Yeungnam University, Dae-dong 214-1, Gyeongsan, 38541 Republic of Korea.

Background: 2,3-Butanediol (2,3-BDO) is a synthetic chemical compound that also can be produced by biomass fermentation, which is gaining share in the global market as an intermediate product for numerous applications, i.e. as liquid fuel or fuel additive. Several metabolic engineering fermentation strategies to enhance the production of 2,3-BDO were developed. However, the recovery of 2,3-BDO from its fermentation broth remains a challenge due to its low concentration and its solubility in water and other components. Thus, a cost-effective recovery process is required to deliver the required purity of 2,3-BDO. This paper presents a new process development and techno-economic analysis for 2,3-BDO purification from a fermentation broth.

Results: Conventional distillation and hybrid extraction-distillation (HED) processes are proposed in this study with detailed optimization and economic analysis. Particularly, a systematic solvent selection method was successfully implemented to determine a good solvent for the proposed HED configuration based on numerous experimental data obtained with each solvent candidate. NRTL and UNIQUAC property methods were evaluated to obtain binary interaction parameters of 2,3-BDO through rigorous Aspen Plus regression and validated using experimental data. Total annual cost (TAC)-based optimization was performed for each proposed configuration. Even though the HED configuration required 9.5% higher capital cost than conventional distillation, placing an extraction column before the distillation column was effective in removing water from the fermentation broth and significantly improved the overall process economics.

Conclusions: Oleyl alcohol was found to be the most suitable solvent for the HED of 2,3-BDO due to its high distribution coefficient and high selectivity. The proposed HED drastically reduced reboiler duty consumption and TAC by up to 54.8 and 25.8%, respectively. The proposed design is expected to be used for the commercial scale of 2,3-BDO production from fermentation process.
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http://dx.doi.org/10.1186/s13068-018-1013-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5785907PMC
January 2018

Formulation, characterization and antimicrobial properties of black cumin essential oil nanoemulsions stabilized by OSA starch.

J Food Sci Technol 2017 Sep 31;54(10):3358-3365. Epub 2017 Aug 31.

State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122 Jiangsu People's Republic of China.

Preparation of oil-in-water nanoemulsions has emerged as a subject of interest for the encapsulation of lipophilic functional ingredients to increase their stability and activity. In this study, black cumin essential oil nanoemulsions (BCO-NE) using different ratios of essential oil with canola and flax seed oils (ripening inhibitors) were formulated and stabilized with octenyl succinic anhydride (OSA) modified waxy maize starch. The nanoemulsions exhibited monomodal size distributions with mean droplet diameter below 200 nm and zeta potential above -30, indicating a strong electrostatic repulsion between the dispersed oil droplets. Further, during storage (4 weeks at 25 °C ± 2) emulsions showed shear thinning phenomena and stability towards coalescence. Antimicrobial properties of nanoemulsions were determined by minimum inhibitory concentration and time-kill method against two Gram-positive bacterial (GPB) strains ( and ). Negatively charged BCO-NE showed prolonged bactericidal activities as compared to pure BCO due to better stability, controlled release and self-assembly with GPB cell membrane followed by destruction of cellular constituents. Our results suggest the application of BCO-NE may be exploited in aqueous food systems for extending the shelf life and other functional properties.
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http://dx.doi.org/10.1007/s13197-017-2800-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5603003PMC
September 2017

Growth kinetics, fatty acid composition and metabolic activity changes of Crypthecodinium cohnii under different nitrogen source and concentration.

AMB Express 2017 Dec 20;7(1):85. Epub 2017 Apr 20.

State Key Laboratory of Food Science & Technology, School of Food Science & Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China.

The effect of varying concentrations of the nitrogen source on the growth kinetics, lipid accumulation, lipid and DHA productivity, and fatty acid composition of C. cohnii was elucidated. Growth of C. cohnii was in three distinct growth stages: cell growth, lipid accumulation and a final lipid turnover stage. Most of lipids were accumulated in lipid accumulation stage (48-120 h) though, slow growth rate was observed during this stage. NaNO supported significantly higher lipid content (26.9% of DCW), DHA content (0.99 g/L) and DHA yield (44.2 mg/g glucose) which were 2.5 to 3.3-folds higher than other N-sources. The maximum level of C16-C18 content (% TFA) was calculated as 43, 54 and 43% in lipid accumulation stage under low nitrogen (LN, 0.2 g/L), medium nitrogen (MN, 0.8 g/L) and high nitrogen (HN, 1.6 g/L) treatments, respectively. Cultures with LN, by down-regulating cell metabolism, trigger onset of lipogenic enzymes. Conversely, NAD/NADP-dependent isocitrate dehydrogenase (NAD/NADP-ICDH) were less active in LN than HN treatments which resulted in retardation of Kreb's Cycle and thereby divert citrate into cytoplasm as substrate for ATP-citrate lyase (ACL). Thereby, ACL and fatty acid synthase (FAS) were most active in lipid accumulation stage at LN treatments. Glucose-6-phosphate dehydrogenase (G6PDH) was more active than malic enzyme (ME) in lipid accumulation stage and showed higher activities in NaNO than other N-sources. This represents that G6PDH contributes more NADPH than ME in C. cohnii. However, G6PDH and ME together seems to play a dual role in offering NADPH for lipid biosynthesis. This concept of ME together with G6PD in offering NADPH for lipogenesis might be novel in this alga and needed to be explored.
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http://dx.doi.org/10.1186/s13568-017-0384-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5399014PMC
December 2017