Chromium-based metal-organic framework, MIL-101 (Cr), assisted hydrothermal pretreatment of teff (Eragrostis tef) straw biomass.

Teff (Eragrostis tef) is a staple crop and holds the biggest share of grains cultivated area in Ethiopia, consequently, a large quantity of Teff straw is produced. The Teff straw was pretreated for the first time with Chromium-based Metal-Organic Framework, MIL-101(Cr), assisted hydrothermal method at temperatures ranging from 160 to 240 °C for 1/2, 1, or 2 h time independently. With an increase of pretreatment severity, the yield of total reducing sugar (TRS) was increased until reaching maximum (185 mg g-1). The identified optimum hydrothermal pretreatment condition, (180 °C and 1 h), had a feature of higher TRS yield and lower furfural concentration. The morphological analysis showed that treated Teff straw had degraded structure, higher surface area, and distorted bundles than native Teff straws. This study insight into MOFs' application in lignocellulose biomass processing, and optimizing the pretreatment condition of Teff straw biomass.

The Impact of Polyethylene Glycol-Modified Chitosan Scaffolds on the Proliferation and Differentiation of Osteoblasts.

The objective of this study was to investigate the influence of polyethylene glycol (PEG) incorporated chitosan scaffolds on osteoblasts proliferation and differentiation. The chitosan polymer was initially modified by the predetermined concentration of the photoreactive azido group for UV-crosslinking and with RGD peptides (N-acetyl-GRGDSPGYG-amide). The PEG was mixed at different ratios (0, 10, and 20 wt%) with modified chitosan in 96-well tissue culture polystyrene plates to prepare CHI-100, CHI-90, and CHI-80 scaffolds. PEG-containing scaffolds exhibited bigger pore size and higher water content compared to unmodified chitosan scaffolds. After 10 days of incubation, the cell number of CHI-90 (1.1 × 106 cells/scaffold) surpasses that of CHI-100 (9.2 × 105 cells/scaffold) and the cell number of CHI-80 (7.6 × 105 cells/scaffold) were significantly lower. The ALP activity of CHI-90 was the highest on the fifth day indicating the favored osteoblasts' early-stage differentiation. Moreover, after 14 days of osteogenic culture, calcium deposition in the CHI-90 scaffolds (2.7 µmol Ca/scaffold) was significantly higher than the control (2.2 µmol Ca/scaffold) whereas on CHI-80 was 1.9 µmol/scaffold. The results demonstrate that PEG-incorporated chitosan scaffolds favored osteoblasts proliferation and differentiation; however, mixing relatively excess PEG (≥20% wt.) had a negative impact on osteoblasts proliferation and differentiation.

Zirconium based metal-organic framework in-situ assisted hydrothermal pretreatment and enzymatic hydrolysis of Platanus X acerifolia exfoliating bark for bioethanol production.

Metal-organic framework (MOF) assisted hydrothermal pretreatment and co-catalysis strategy based on UiO-66 MOF is developed for the first time. The Planetree exfoliating bark was pretreated with or without UiO-66 assisted hydrothermal method at a temperature ranging from 160 to 240 °C for 1-3 h residence. With the rise of pretreatment severity, the total reducing sugar (TRS) was increased till reached maximum, 180 mg g-1, in the presence of UiO-66. The fitting models validate the optimal hydrothermal condition was at 180 °C and 1 h, which was characterized with high TRS and very low yield of furfural and HMF. The TRS from enzymatic hydrolysis reaches maximum, 391 mg g-1, in the presence of MOF co-catalysis and the maximum ethanol yield achieved was 73%. Altered morphology, higher surface area and porosity are noticed after MOF assisted hydrothermal pretreatment. This study insights the MOFs' application in lignocellulose biomass processing.

Immobilization of functional polymers on poly(4-benzoyl-pxylylene-co-p-xylylene) films via photochemical conjugation for modulation of cell adhesion.

Surface modification with functional materials, such as anti-fouling or thermal responsive polymers, on biomedical devices benefits their clinical performance. Simple and versatile technologies, which could be applied to a wide variety of substrates, are still highly desirable. Chemical vapor deposition (CVD) of 4-benzoyl-[2,2]paracyclophane (Benzoyl-PPX) layers attracts much attention because the photoreactive platform could be deposited onto almost every substrate for the conjugation of functional molecules. In this study, poly(ethylene glycol) (PEG) was conjugated onto Benzoyl-PPX via UV illumination. The deposited PEG films could effectively reduce protein adsorption and cell attachment. The low-fouling properties of the PEG films were positively correlated with the molecular weight and concentration of PEG. We found that a PEG film, thicker than 16 nm and with a water contact angle of 30°, is a prerequisite for effective inhibition of cell attachment. We also demonstrated that the PEG coating was stable under acidic and basic environments. Furthermore, poly(N-isopropyl acrylamide), PNIPAAm, could be also tethered on the Benzoyl-PPX via UV illumination, and possessed thermal-responsive properties. Intact cell sheets could be released from the PNIPAAm film by decreasing culture temperature. The results indicate that Benzoyl-PPX is an excellent photoreactive platform for the conjugation of functional polymers for modulation of cell attachment.

Hydrolysis of cellulose using cellulase physically immobilized on highly stable zirconium based metal-organic frameworks.

Developing a new cellulase-MOF composite system with enhanced stability and reusability for cellulose hydrolysis was aimed. Physical adsorption strategy was employed to fabricate two cellulase composites, and the activity of composite was characterized by hydrolysis of carboxymethyl cellulose. The NH2 functionalized UiO-66-NH2 MOF exhibited higher protein loading than the precursor UiO-66, due to the extra anchor sites of NH2 groups. The immobilized cellulase showed enhanced thermostability, pH tolerance and lifetime. The maximum activity attained at 55 °C could be kept 85% when used at 80 °C, and the residual activities were 72% after ten cycles and 65% after 30 days storage. The abundant NH2 and COOH groups of MOF adsorb cellulase and enhance its stability, and the resulted heterogeneity offered the opportunity of recovering composite via mild centrifuge. The findings suggest the promising future of developing cellulase-MOF composite with ultrahigh activities and stabilities for practical application.

Poly(acrylic acid) nanogel as a substrate for cellulase immobilization for hydrolysis of cellulose.

Cellulase was adsorbed onto poly(acrylic acid), PAA, nanogel, that was fabricated via inverse-phase microemulsion polymerization. The PAA nanogel was around 150nm in diameter and enriched with carboxyl groups. The surface charge of PAA nanogel depended on the pHs of the environment and affected the adsorption of cellulase. The temperature stability of the immobilized cellulase was greatly enhanced in comparison to the free enzyme, especially at high temperature. At 80°C, the immobilized cellulase remained ∼75% of hydrolytic activity, in comparison to ∼55% for the free cellulase. Furthermore, the immobilized cellulase was more active than the free enzyme in acidic buffers. The immobilized cellulase could be recovered via centrifugation and can be used repeatedly, although the recovery ratio needs further improvement. In conclusion, PAA nanogel has the potential in the application of enzyme immobilization for biochemical processes.

Impact of pretreatments on morphology and enzymatic saccharification of shedding bark of Melaleuca leucadendron.

The effects of subcritical water (SCW) and dilute acid pretreatments on the shedding bark of Melaleuca leucadendron (paper bark tree, PBT) biomass morphology, crystallinity index (CrI) and enzymatic saccharification were studied. The morphology of PBT bark was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. SCW pretreatment mainly extracted amorphous parts of the biomass hence its CrI increased, partial decrystallization of cellulose and exposing of intact nanofibers of cellulose were observed for SCW pretreatment at 180°C. On the other hand, dilute acid pretreatment at 160°C exhibited a large decrease in CrI, an increase in surface area, a decrease in lignin content and decrystallization of cellulose as well as the peel-off and degradation of some nanofiber bundles. Dilute acid and SCW pretreatments of PBT biomass resulted in about 4.5 fold enhancement in glucose release relative to the untreated one.

Bioethanol production from pretreated Melaleuca leucadendron shedding bark--simultaneous saccharification and fermentation at high solid loading.

Bioethanol production from the shedding bark of Melaleuca leucadendron (Paper-bark Tree, PBT) was studied using subcritical water (SCW) pretreatment at various severities (So). High ethanol production was attained by implementing a factorial design on three parameters (So, solid loading and enzyme loading) in simultaneous saccharification and fermentation (SSF) mode. Ethanol concentration of 63.2 g L(-1) corresponding to ethanol yield of 80.9% were achieved from pretreated biomass (So=2.37) at 0.25 g mL(-1) solid and 16 FPU g(-1) glucan enzyme loadings. Similarly at 0.15 g mL(-1) solid loadings both high ethanol concentration (43.7 g L(-1)) and high ethanol yield (91.25%) were achieved. Regression analysis of experimental results shows that all process parameters had significant role on maximum ethanol production, glucose solubility, ethanol yield and ethanol volumetric productivity. SSF of SCW treated PBT biomass is economically feasible for production of bioethanol.

Maximizing biodiesel production from Yarrowia lipolytica Po1g biomass using subcritical water pretreatment.

The yeast Yarrowia lipolytica Po1g is one of the oleaginous microorganisms with a potential for biodiesel production. Sub-critical water (SCW) treatment has been known as an effective method for increasing the amount of extractable lipids in microorganisms. In this work, the amount of neutral lipids and fatty acid profiles in neutral lipids extracted from Y. lipolytica Po1g with and without SCW pre-treatment were investigated. The effects of temperature (125, 150 or 175°C), amount of water (20, 30 or 40 mL/g biomass) and time (10, 20 or 30 min) showed that maximum neutral lipid (42.69%, w/w) could be achieved at 175°C using 20 mL water for 20 min. The maximum neutral lipid from unpretreated samples was 23.21%. No difference in fatty acid profiles was observed, but long chain fatty acids were observed in higher amount in SCW pretreated samples. SCW pretreatment increased biodiesel yield twofold.