Publications by authors named "Naijia Hao"

13 Publications

  • Page 1 of 1

Phototunable Lignin Plastics to Enable Recyclability.

ChemSusChem 2021 Oct 6;14(19):4260-4269. Epub 2021 Aug 6.

Synthetic and Systems Biology Innovation Hub, Texas A&M University, College Station, TX 77843, USA.

The accumulation of non-degradable petrochemical plastics imposes a significant threat to the environment and ecosystems. We addressed this challenge by designing a new type of phototunable plastics based on the unique lignin chemistry to enable readily end-life recycling. The advanced material design leveraged the efficient photocatalytic lignin depolymerization by ZnO nanoparticles to build lignin-polymethyl methacrylate (PMMA)-ZnO blends. We first demonstrated the highly effective phototunable lignin depolymerization in the complex polymer blend matrix and explored the molecular mechanisms. The technical barriers of mechanical property and recycling processing were then addressed by a new blend design with lignin core grafted with PMMA polymer. The new process has resulted in a new type of PMMA-g-lignin blend, which significantly improved the mechanical properties, making it comparable to PMMA alone. More importantly, the mechanical properties of the UV-treated blend decreased drastically in the new design, whereas the properties did not reduce in the non-grafted blends upon UV exposure. The results highlighted that the new blend design based on graftization maximized the impact of lignin depolymerization on blend structure and recyclability. Based on the results, we developed a process integrating UV and alkaline treatments to recycle PMMA for plastics and fractionated lignin for bioconversion or other applications in the new phototunable plastics.
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http://dx.doi.org/10.1002/cssc.202101040DOI Listing
October 2021

Transforming biorefinery designs with 'Plug-In Processes of Lignin' to enable economic waste valorization.

Nat Commun 2021 06 23;12(1):3912. Epub 2021 Jun 23.

Synthetic and Systems Biology Innovation Hub, Texas A&M University, College Station, TX, USA.

Biological lignin valorization has emerged as a major solution for sustainable and cost-effective biorefineries. However, current biorefineries yield lignin with inadequate fractionation for bioconversion, yet substantial changes of these biorefinery designs to focus on lignin could jeopardize carbohydrate efficiency and increase capital costs. We resolve the dilemma by designing 'plug-in processes of lignin' with the integration of leading pretreatment technologies. Substantial improvement of lignin bioconversion and synergistic enhancement of carbohydrate processing are achieved by solubilizing lignin via lowering molecular weight and increasing hydrophilic groups, addressing the dilemma of lignin- or carbohydrate-first scenarios. The plug-in processes of lignin could enable minimum polyhydroxyalkanoate selling price at as low as $6.18/kg. The results highlight the potential to achieve commercial production of polyhydroxyalkanoates as a co-product of cellulosic ethanol. Here, we show that the plug-in processes of lignin could transform biorefinery design toward sustainability by promoting carbon efficiency and optimizing the total capital cost.
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http://dx.doi.org/10.1038/s41467-021-23920-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222318PMC
June 2021

Enhancement of polyhydroxyalkanoate production by co-feeding lignin derivatives with glycerol in Pseudomonas putida KT2440.

Biotechnol Biofuels 2021 Jan 7;14(1):11. Epub 2021 Jan 7.

Bioproducts, Sciences & Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, WA, 99354, USA.

Background: Efficient utilization of all available carbons from lignocellulosic biomass is critical for economic efficiency of a bioconversion process to produce renewable bioproducts. However, the metabolic responses that enable Pseudomonas putida to utilize mixed carbon sources to generate reducing power and polyhydroxyalkanoate (PHA) remain unclear. Previous research has mainly focused on different fermentation strategies, including the sequential feeding of xylose as the growth stage substrate and octanoic acid as the PHA-producing substrate, feeding glycerol as the sole carbon substrate, and co-feeding of lignin and glucose. This study developed a new strategy-co-feeding glycerol and lignin derivatives such as benzoate, vanillin, and vanillic acid in Pseudomonas putida KT2440-for the first time, which simultaneously improved both cell biomass and PHA production.

Results: Co-feeding lignin derivatives (i.e. benzoate, vanillin, and vanillic acid) and glycerol to P. putida KT2440 was shown for the first time to simultaneously increase cell dry weight (CDW) by 9.4-16.1% and PHA content by 29.0-63.2%, respectively, compared with feeding glycerol alone. GC-MS results revealed that the addition of lignin derivatives to glycerol decreased the distribution of long-chain monomers (C10 and C12) by 0.4-4.4% and increased the distribution of short-chain monomers (C6 and C8) by 0.8-3.5%. The H-C HMBC, H-C HSQC, and H-H COSY NMR analysis confirmed that the PHA monomers (C6-C14) were produced when glycerol was fed to the bacteria alone or together with lignin derivatives. Moreover, investigation of the glycerol/benzoate/nitrogen ratios showed that benzoate acted as an independent factor in PHA synthesis. Furthermore, H, C and P NMR metabolite analysis and mass spectrometry-based quantitative proteomics measurements suggested that the addition of benzoate stimulated oxidative-stress responses, enhanced glycerol consumption, and altered the intracellular NAD/NADH and NADPH/NADP ratios by up-regulating the proteins involved in energy generation and storage processes, including the Entner-Doudoroff (ED) pathway, the reductive TCA route, trehalose degradation, fatty acid β-oxidation, and PHA biosynthesis.

Conclusions: This work demonstrated an effective co-carbon feeding strategy to improve PHA content/yield and convert lignin derivatives into value-added products in P. putida KT2440. Co-feeding lignin break-down products with other carbon sources, such as glycerol, has been demonstrated as an efficient way to utilize biomass to increase PHA production in P. putida KT2440. Moreover, the involvement of aromatic degradation favours further lignin utilization, and the combination of proteomics and metabolomics with NMR sheds light on the metabolic and regulatory mechanisms for cellular redox balance and potential genetic targets for a higher biomass carbon conversion efficiency.
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http://dx.doi.org/10.1186/s13068-020-01861-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7792162PMC
January 2021

Stereolithography 3D Printing of Lignin-Reinforced Composites with Enhanced Mechanical Properties.

ACS Omega 2019 Dec 20;4(23):20197-20204. Epub 2019 Nov 20.

Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States.

Due to the availability, biodegradability, and biological effects, lignin has emerged as an interesting alternative to petroleum-based compounds for developing sustainable chemicals, materials, and composites. In this study, lignin at various concentrations was incorporated into methacrylate resin via solution blending to fabricate lignin-reinforced composites using stereolithography apparatus three-dimensional printing. Softwood kraft lignin in the amounts of 0.2, 0.4, 0.5, 0.8, and 1.0 wt % in the methacrylate resin was used as a printing ink, and the gel contents and relative contents of the residual resin in the printed samples with various lignin concentrations were measured. The effects of the lignin on the ultimate mechanical properties of the non-postcured and postcured printed composites were determined. The tensile testing results revealed that the incorporation of lignin in the composite increased the tensile strength by 46-64% and Young's modulus by 13-37% for the postcured printed composites compared with that of the control sample (no lignin added). Employing a 0.4 wt % softwood kraft lignin, the tensile strength of the postcured printed composite reached the highest value of 49.0 MPa, which was a 60% increase in comparison to that of the control sample with 30.7 MPa. Scanning electron microscopy images of the fracture samples illustrated that the lignin-incorporated composites exhibited a rougher fracture surface that can presumably dissipate the stress, which could be a contributing factor for the mechanical enhancement.
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http://dx.doi.org/10.1021/acsomega.9b02455DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893962PMC
December 2019

Determination of hydroxyl groups in biorefinery resources via quantitative P NMR spectroscopy.

Nat Protoc 2019 09 7;14(9):2627-2647. Epub 2019 Aug 7.

Departments of Chemistry and Forest Biomaterials, North Carolina State University, Raleigh, NC, USA.

The analysis of chemical structural characteristics of biorefinery product streams (such as lignin and tannin) has advanced substantially over the past decade, with traditional wet-chemical techniques being replaced or supplemented by NMR methodologies. Quantitative P NMR spectroscopy is a promising technique for the analysis of hydroxyl groups because of its unique characterization capability and broad potential applicability across the biorefinery research community. This protocol describes procedures for (i) the preparation/solubilization of lignin and tannin, (ii) the phosphitylation of their hydroxyl groups, (iii) NMR acquisition details, and (iv) the ensuing data analyses and means to precisely calculate the content of the different types of hydroxyl groups. Compared with traditional wet-chemical techniques, the technique of quantitative P NMR spectroscopy offers unique advantages in measuring hydroxyl groups in a single spectrum with high signal resolution. The method provides complete quantitative information about the hydroxyl groups with small amounts of sample (~30 mg) within a relatively short experimental time (~30-120 min).
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http://dx.doi.org/10.1038/s41596-019-0191-1DOI Listing
September 2019

Investigating the correlation of biomass recalcitrance with pyrolysis oil using poplar as the feedstock.

Bioresour Technol 2019 Oct 1;289:121589. Epub 2019 Jun 1.

Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA; Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee, Knoxville, TN 37996, USA; The Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. Electronic address:

Pyrolysis of five poplar samples with differing degrees of recalcitrance was performed; the correlations between the poplar enzymatic hydrolysis glucose yields and the physicochemical properties of pyrolysis product were investigated in this study. Sugar release of five poplar samples varied from 48.1 to 112.3 mg/g for glucose, and 12.0 to 32.4 mg/g for xylose. The yield of pyrolysis products was calculated and the molecular weight distribution of pyrolysis oils was measured by GPC, ranging from 268 to 289 g/mol for its weight-average molecular weight. GC-MS analysis of the bio-oil exhibited a strong correlation between biomass recalcitrance and guaiacyl-type structures in bio-oils. The correlation between biomass recalcitrance and the ratio of syringyl-to-guaiacyl-type-related structures was also assessed. The results from quantitative P NMR indicated some correlation between biomass recalcitrance and the guaiacyl hydroxyl groups in bio-oils. These results illustrate correlations and differences between converting biomass to biofuels via the biological and thermal platform.
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http://dx.doi.org/10.1016/j.biortech.2019.121589DOI Listing
October 2019

One-pot transformation of lignocellulosic biomass into crude bio-oil with metal chlorides via hydrothermal and supercritical ethanol processing.

Bioresour Technol 2019 Sep 17;288:121500. Epub 2019 May 17.

Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, United States; Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Center for Renewable Carbon, Department of Forestry, Wildlife, and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, TN 37996, United States. Electronic address:

Grape seeds were deconstructed in both hydrothermal and supercritical ethanol media with a combination of two metal chlorides (TiCl:MgCl) to produce bio-oils. The use of metal chloride additives in supercritical ethanol achieved the highest bio-oil yield of 49.2 wt% (300 °C, 30 min). Both the hydrothermal and supercritical ethanol deconstruction with the additives (TiCl:MgCl = 4 mmol:4mmol) produced the bio-oils with a higher heating value (HHV) of 35 MJ/Kg. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oils showed that the major products in bio-oils from the hydrothermal deconstruction were acids while the majority products in bio-oils form the supercritical ethanol deconstruction were esters. Nuclear magnetic resonance (NMR) data of the bio-oils suggested that both hydrothermal and supercritical ethanol deconstruction with metal chlorides significantly reduced the non-condensed OH and oxygenated lignin sub-units in bio-oils; while only supercritical ethanol deconstruction with metal chlorides reduced the aliphatic OH and O-alkylated structures in bio-oils.
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http://dx.doi.org/10.1016/j.biortech.2019.121500DOI Listing
September 2019

Cross-linked poly(methyl vinyl ether-co-maleic acid)/poly(ethylene glycol)/nanocellulosics foams via directional freezing.

Carbohydr Polym 2019 Jun 22;213:346-351. Epub 2019 Feb 22.

Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN, 37996, USA; Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee Institute of Agriculture, Knoxville, TN, 37996, USA; UTK-ORNL Joint Institute for Biological Science, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA. Electronic address:

Aligned micro- and nanoporous materials have gained tremendous interest since they provide great potential in organic electronics, absorbents, biomedicine and tissue engineering. Herein, cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) cross-linked with poly(methyl vinyl ether-co-maleic acid) (PMVEMA) and poly(ethylene glycol) (PEG) foams were prepared by both the directional and un-directional freezing techniques. Aligned three-dimensional porous structures were observed for the directional frozen foams after lyophilization via scanning electron microscope (SEM). As a result, these highly organized structures exhibited enhanced mechanical performance properties. Particularly, for the 25% CNF foams, the compression modulus increased 60% compared with the un-directional frozen samples. These nanocellulosics-based foams could absorb up to 10-fold water of their initial weight with excellent water stability when immersed in water for more than 48 h. Overall, this study describes a novel process combining cross-linking and directional freezing which successfully fabricates naturally derived foams with anisotropic structure.
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http://dx.doi.org/10.1016/j.carbpol.2019.02.073DOI Listing
June 2019

Kinetic understanding of nitrogen supply condition on biosynthesis of polyhydroxyalkanoate from benzoate by Pseudomonas putida KT2440.

Bioresour Technol 2019 Feb 12;273:538-544. Epub 2018 Nov 12.

Bioproducts, Sciences, and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, WA 99354, USA. Electronic address:

Nitrogen supply is critical to the synthesis of intracellular PHA in various bacteria. However, the specific role of the nitrogen in synthesizing PHA from benzoate, a lignin model compound use for the study of bacteria catabolism of aromatics, is still not clear. In this study, two culture conditions were maintained for Pseudomonas putida KT2440 to produce PHA using benzoate as a carbon source. Under nitrogen-limited and surplus conditions, the accumulation of PHA was to 37.3% and 0.25% of cell dry weight, respectively. A model fit to the kinetics of biomass growth and PHA accumulation showed good agreement with data. GC-MS and NMR showed that PHA contained six hydroxyl fatty acid monomers under nitrogen-limited conditions, while two monomers were identified under nitrogen surplus conditions. The average molecular weight of PHA increased after the nitrogen source was exhausted. These results provide a promising strategy for optimization of lignin to PHA yields.
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http://dx.doi.org/10.1016/j.biortech.2018.11.046DOI Listing
February 2019

Ethanol: A Promising Green Solvent for the Deconstruction of Lignocellulose.

ChemSusChem 2018 Oct 24;11(20):3559-3575. Epub 2018 Sep 24.

Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN, 37916, USA.

Growing energy demand, environmental impact, energy security issues, and rural economic development have encouraged the development of sustainable renewable fuels. Nonfood lignocellulosic biomass is a suitable source for sustainable energy because the biomass feedstocks are low cost, abundant, and carbon neutral. Recent thermochemical conversion studies are frequently directed at converting biomass into high-quality liquid fuel precursors or chemicals in a single step. Supercritical ethanol has been selected as a promising solvent medium to deconstruct lignocellulosic biomass because ethanol has extraordinary solubility towards lignocellulosic biomass and can be resourced from cellulosic ethanol facilities. This review provides a critical insight into both catalytic and noncatalytic strategies of lignocellulose deconstruction. In this context, the supercritical ethanol deconstruction pathways are thoroughly reviewed; GC-MS, 1D and 2D NMR spectroscopy, and elemental analysis strategies towards liquid biomass deconstruction products are also critically presented. This review aims to provide readers a broad and accurate roadmap of novel biomass to biofuel conversion techniques.
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http://dx.doi.org/10.1002/cssc.201801291DOI Listing
October 2018

Laccase-mediated functionalization of chitosan with 4-hexyloxyphenol enhances antioxidant and hydrophobic properties of copolymer.

J Biotechnol 2018 Mar 4;269:8-15. Epub 2018 Feb 4.

College of Paper and Plant Resources Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, Shandong, China.

An effective method to functionalize chitosan with 4-hexyloxyphenol (HP) under homogeneous reaction conditions was developed using laccase as the catalyst. The resulting copolymer was characterized for chemical structure, grafted-HP content, surface morphology, thermal stability, antioxidant capacity, hydrophobic properties and tensile strength. Solid-state C NMR spectrum confirmed the incorporation of HP onto chitosan. X-ray diffraction (XRD) showed a decrease in the degree of crystallinity for laccase/HP treated chitosan compared to pure chitosan. The grafted-HP content in laccase/HP-treated chitosan first increased and then declined with increase of the initial HP/chitosan ratio. A heterogeneous surface with spherical particles on the laccase/HP treated chitosan was observed by environmental scanning electron microscopy (ESEM) and scanning probe microscopy (SPM). The laccase/HP treatment of chitosan improved the thermal stability of copolymer. More significantly, the HP functionalized chitosan showed greatly improved ABTS and DPPH radicals scavenging capacity, compared with pure chitosan. The hydrophobicity property of the HP functionalized chitosan also significantly increased although its tensile strength decreased. This new type of composite with double functionalities (i.e., antioxidant and hydrophobic) could potentially be used as food packaging materials or coating agents.
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http://dx.doi.org/10.1016/j.jbiotec.2018.01.015DOI Listing
March 2018

Characterization of products from hydrothermal carbonization of pine.

Bioresour Technol 2017 Nov 27;244(Pt 1):78-83. Epub 2017 Jul 27.

Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA; Joint Institute of Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA. Electronic address:

This study aims to reveal the structural features and reaction pathways for solid-liquid products from hydrothermal carbonization of Loblolly pine, where the solid products can be used as catalysts, adsorbents and electrode materials while liquid products can be treated yielding fuels and platform chemicals. Results revealed when treated at 240°C, cellulose and hemicellulose were degraded, in part, to 5-hydroxy-methyl furfural and furfural which were further transformed to aromatic structures via ring opening and Diels Alder reactions. Lignin degradation and formation of carbon-carbon bonds, forming aromatic motifs in the presence of furanic compounds connected via aliphatic bridges, ether or condensation reactions. After hydrothermal treatment, condensed aromatic carbon materials with methoxy groups were recovered with high fixed carbon content and HHV. The recovered liquid products are lignin-like value-added chemicals consisting of furfural and polyaromatic structure with alkanes and carboxyl, their total hydroxyl group content decreased when increasing reaction time.
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http://dx.doi.org/10.1016/j.biortech.2017.07.138DOI Listing
November 2017

A bright red fluorescent cyanine dye for live-cell nucleic acid imaging, with high photostability and a large Stokes shift.

J Mater Chem B 2014 May 21;2(18):2688-2693. Epub 2014 Mar 21.

State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2 Linggong Road, Hi-tech Zone, Dalian 116024, P.R. China.

Many probes for nucleic acids are available, but few of them satisfy multiple criteria, particularly high photostability to endure laser scanning. We report a cyanine dye TO3-CN for the first time, synthesised by introducing a CN group to the trimethine chain of the classical red emitting TO-3 dye to improve its photostability, as well as their spectral properties and interaction with nucleic acids. TO3-CN shows excellent light fastness and a large fluorescence Stokes shift (more than 40 nm). Because of its sensitive fluorescence response to nucleic acids with a large fluorescence quantum yield (more than 0.7) and low cytotoxicity, this dye may be a potential candidate for nucleic acid detection in vitro and intracellular fluorescence imaging.
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http://dx.doi.org/10.1039/c3tb21844aDOI Listing
May 2014
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