Novel amphiphilic polyvinylpyrrolidone functionalized silicone particles as carrier for low-cost lipase immobilization

The high catalytic activity, specificity and stability of immobilized lipase have been attracting great interest. How to reduce the cost of support materials has always been a hot topic in this field. Herein, for the development of low-cost immobilized lipase, we demonstrate an amphiphilic polyvinylpyrrolidone (PVP) grafted on silicone particle (SP) surface materials (SP-PVP) with a rational design based on interfacial activation and solution polymerization. Meanwhile, hydrophilic pristine SP and hydrophobic polystyrene-corded silicone particles (SP-Pst) were also prepared for lipase immobilization. SP-PVP was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetry. Our results indicated that the lipase loading amount on the SP-PVP composites was about 215 mg of protein per gram. In the activity assay, the immobilized lipase SP-PVP@CRL exhibited higher catalysis activity and better thermostability and reusability than SP@CRL and SP-Pst@CRL. The immobilized lipase retained more than 54% of its initial activity after 10 times of re-use and approximately trended to a steady rate in the following cycles. By introducing the interesting amphiphilic polymer to this cheap and easily obtained SP surface, the relative performance of the immobilized lipase can be significantly improved, facilitating interactions between the low-cost support materials and lipase.

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Effect of calcination temperature on rare earth tailing catalysts for catalytic methane combustion

Green Processing and Synthesis ◽

10.1515/gps-2020-0053 ◽

2020 ◽

Vol 9 (1) ◽

pp. 734-743

Author(s):

Ran Zhao ◽

ZiChen Tian ◽

Zengwu Zhao

Keyword(s):

Rare Earth ◽

Mine Tailings ◽

Photoelectron Spectroscopy ◽

Methane Combustion ◽

Space Velocity ◽

High Catalytic Activity ◽

Reduction Peak ◽

X Ray ◽

Different Temperatures ◽

Bayan Obo

AbstractBayan Obo tailings are rich in rare earth elements (REEs), iron, and other catalytic active substances. In this study, mine tailings were calcined at different temperatures and tested for the catalytic combustion of low-concentration methane. Upon calcination at 600°C, high catalytic activity was revealed, with 50% CH4 conversion at 587°C (space velocity of 12,000 mL/g h). The physicochemical properties of catalysts were characterized using thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, hydrogen temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). Compared to the raw ore sample, the diffraction peak intensity of Fe2O3 increased post calcination, whereas that of CeCO3F decreased. A porous structure appeared after the catalyst was calcined at 600°C. Additionally, Fe, Ce, Ti, and other metal elements were more highly dispersed on the catalyst surface. H2-TPR results revealed a broadening of the reduction temperature range for the catalyst calcined at 600°C and an increase in the reduction peak. XPS analysis indicated the presence of Ce in the form of Ce3+ and Ce4+ oxidation states and the coexistence of Fe in the form of Fe2+ and Fe3+. Moreover, XPS revealed a higher surface Oads/Olatt ratio. This study provides evidence for the green reuse of Bayan Obo mine tailings in secondary resources.

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Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications

International Journal of Molecular Sciences ◽

10.3390/ijms22094433 ◽

2021 ◽

Vol 22 (9) ◽

pp. 4433

Author(s):

Eun Sung Lee ◽

Byung Seok Cha ◽

Seokjoon Kim ◽

Ki Soo Park

Keyword(s):

Photoelectron Spectroscopy ◽

Low Cost ◽

Stokes Shift ◽

Gold Nanoclusters ◽

Human Colon ◽

Cellular Imaging ◽

Metal Nanoclusters ◽

Human Colon Cancer ◽

X Ray ◽

High Concentrations

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

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Yttrium Doped TiO2 Thin Film for Gas Sensing Application Prepared by Spin Coating Method

10.21203/rs.3.rs-106302/v1 ◽

2020 ◽

Author(s):

M Abdul Kaiyum ◽

Naim Ahmed ◽

Arif Alam ◽

M Shamimur Rahman

Keyword(s):

Thin Film ◽

Photoelectron Spectroscopy ◽

Gas Sensing ◽

Low Cost ◽

Pure Titanium ◽

X Ray ◽

Sensing Applications ◽

Coating Method ◽

Set Up ◽

Spin Coater

Abstract Yttrium (Y) doped and pure Titanium Di-oxide (TiO2) thin films were prepared by using spin coater. The coater was set up in laboratory with low cost investment. The films were calcined at 450 °C for 1 hour. For characterization, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM) were carried out. LCR Bridge - GW Instek LCR-821 was used for gas sensing applications. XPS showed that the change of electronic structure due to Y doping. SEM and AFM analysis were carried out to determine the surface morphology of the films. Yttrium (Y) decreased the crystallite size of the films and increased the surface roughness and porosity value, which was very good for many sensing applications. Gas sensing property of the deposited films were improved by the incorporation of yttrium impurities and the sensing property improved almost two times than pure TiO2 thin film. Different researches have been done their research related to this topic but no one researchers provide a precise explanation of their results, authors of this research have tried to do that. Moreover the films were prepared by a simple spin coater to reduce the production cost also.

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Improving the Performance of Zn-Air Batteries with N-Doped Electroexfoliated Graphene

Materials ◽

10.3390/ma13092115 ◽

2020 ◽

Vol 13 (9) ◽

pp. 2115 ◽

Cited By ~ 2

Author(s):

Anna Ilnicka ◽

Malgorzata Skorupska ◽

Piotr Romanowski ◽

Piotr Kamedulski ◽

Jerzy P. Lukaszewicz

Keyword(s):

Catalytic Activity ◽

Photoelectron Spectroscopy ◽

Noble Metals ◽

Electrode Materials ◽

Low Cost ◽

Rapid Development ◽

Reduction Reaction ◽

Graphene Sheets ◽

High Catalytic Activity ◽

Energy Storage Devices

The constantly growing demand for active, durable, and low-cost electrocatalysts usable in energy storage devices, such as supercapacitors or electrodes in metal-air batteries, has triggered the rapid development of heteroatom-doped carbon materials, which would, among other things, exhibit high catalytic activity in the oxygen reduction reaction (ORR). In this article, a method of synthesizing nitrogen-doped graphene is proposed. Few-layered graphene sheets (FL-graphene) were prepared by electrochemical exfoliation of commercial graphite in a Na2SO4 electrolyte with added calcium carbonate as a separator of newly-exfoliated FL-graphene sheets. Exfoliated FL-graphene was impregnated with a suspension of green algae used as a nitrogen carrier. Impregnated FL-graphene was carbonized at a high temperature under the flow of nitrogen. The N-doped FL-graphene was characterized through instrumental methods: high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Electrochemical performance was determined using cyclic voltamperometry and linear sweep voltamperometry to check catalytic activity in ORR. The N-doped electroexfoliated FL-graphene obeyed the four-electron transfer pathways, leading us to further test these materials as electrode components in rechargeable zinc-air batteries. The obtained results for Zn-air batteries are very important for future development of industry, because the proposed graphene electrode materials do not contain any heavy and noble metals in their composition.

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Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

Applied Sciences ◽

10.3390/app9040793 ◽

2019 ◽

Vol 9 (4) ◽

pp. 793 ◽

Cited By ~ 5

Author(s):

Camila Zequine ◽

Fangzhou Wang ◽

Xianglin Li ◽

Deepa Guragain ◽

S.R. Mishra ◽

...

Keyword(s):

Fuel Cells ◽

Photoelectron Spectroscopy ◽

High Performance ◽

Nickel Foam ◽

Low Cost ◽

Agricultural Waste ◽

Bifunctional Catalyst ◽

X Ray Diffraction ◽

X Ray ◽

Electroactive Material

The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost.

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An Efficient Simple Hydrothermal Method to Synthesis FeS2 Microspheres and their Optical Property

Materials Science Forum ◽

10.4028/www.scientific.net/msf.847.72 ◽

2016 ◽

Vol 847 ◽

pp. 72-77

Author(s):

Yu Xuan Liang ◽

Peng Peng Bai ◽

Shu Qi Zheng

Keyword(s):

Photoelectron Spectroscopy ◽

Low Cost ◽

Wave Length ◽

Functional Materials ◽

Optical And Electrical Properties ◽

X Ray Diffraction ◽

Synthetic Sample ◽

X Ray ◽

New Type ◽

Good Uniformity

Pyrite (FeS2) is an important semiconductor material which shows various excellent optical and electrical properties and extensive applied prospect as a new-type, photoelectrical functional materials. In this study, a low cost and efficient simple hydrothermal two-step synthetic method was given to obtain FeS2 microspheres with 2-3 μm in diameter. The obtained products were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet and visible spectrophotometer (UV-Vis). XRD showed that the synthetic sample consisted of two crystal structures of FeS2, pyrite and marcasite. SEM observation indicated that FeS2 microspheres were well crystallized and had good uniformity. UV-Vis spectrum had a strong optical absorption in the region of 200-400 nm wave length. The reaction temperature had an impact on the size of FeS2 microspheres. A possible mechanism for the size of the FeS2 microspheres generated at high temperature is smaller than that at low temperature is discussed.

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Removal Efficiency and Mechanism of Cr(VI) from Aqueous Solution by Maize Straw Biochars Derived at Different Pyrolysis Temperatures

Water ◽

10.3390/w11040781 ◽

2019 ◽

Vol 11 (4) ◽

pp. 781 ◽

Cited By ~ 6

Author(s):

Wang ◽

Zhang ◽

Keyword(s):

Aqueous Solution ◽

Removal Efficiency ◽

Photoelectron Spectroscopy ◽

Low Cost ◽

X Ray ◽

Removal Capacity ◽

Maize Straw ◽

Efficient Adsorbent ◽

Positively Charged ◽

Maximum Removal

The removal efficiency and mechanism of Cr(VI) removal from aqueous solution on semi-decomposed maize straw biochars pyrolyzed at 300 to 600 °C were investigated. The removal of Cr(VI) by the biochars decreased with pyrolysis temperature increasing from 300 to 600 °C, and the maximum removal capacity of Cr(VI) for maize straw biochar pyrolyzed at 300 °C was 91 mg/g at pH 2.0. The percentage removal of Cr(VI) rapidly decreased with pH increasing from 2.0 to 8.0, with the maximum (>99.9%) at pH 2.0. The variation of Cr(VI) and Cr(III) concentrations in the solution after reaction showed that Cr(VI) concentration decreased while Cr(III) increased and the equilibrium was reached after 48 h, while the redox potential after reaction decreased due to Cr(VI) reduction. X-ray photoelectron spectroscopy (XPS) semi-quantitative analysis showed that Cr(III) accounted for 75.7% of the total Cr bound to maize straw biochar, which indicated reductive adsorption was responsible for Cr(VI) removal by the biochars. Cr(VI) was firstly adsorbed onto the positively charged biochar surface and reduced to Cr(III) by electrons provided by oxygen-containing functional groups (e.g., C=O), and subsequently part of the converted Cr(III) remained on the biochar surface and the rest released into solution. Fourier transform infrared (FTIR) data indicated the participation of C=O, Si–O, –CH2 and –CH3 groups in Cr(VI) removal by the biochars. This study showed that maize straw biochar pyrolyzed at 300 °C for 2 h was one low-cost and efficient adsorbent for Cr(VI) removal from aqueous solution.

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Optimum Conditions for Lipase Immobilization on Halloysitum Rubrum

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.864-867.465 ◽

2013 ◽

Vol 864-867 ◽

pp. 465-471

Author(s):

Tao Deng ◽

Jun Wei Xu ◽

Li Huang ◽

Tao Li ◽

Xu Ya Yu

Keyword(s):

Response Surface Methodology ◽

Experimental Design ◽

Immobilized Lipase ◽

Candida Rugosa ◽

Initial Activity ◽

Optimum Conditions ◽

Lipase Immobilization ◽

Support Materials ◽

Optimum Ph ◽

Support Ratio

In this study, we use natural halloysitum rubrum as novel support materials to immobilize Candida rugosa lipase. The response surface methodology with a four-factor three-level Box-Behnken experimental design was used to evaluate the effects of immobilization parameters, such as pH (4.0 to 6.0), immobilization temperature (25 °C to 35 °C), enzyme/support ratio (0.1 to 0.3, w/w), and immobilization time (1 h to 2 h), on the activity of immobilized lipase. The optimum pH, temperature, enzyme/support ratio, and time for immobilized lipase activity (376.09 U/g) were 5.17, 29.65 °C, 0.3 (w/w), and 1.63 h, respectively. After 15 repeated uses, the immobilized lipase still retained 80% of its initial activity, which indicates good reusability.

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Low Cost Integrated Sensors Utilizing Patterned Nano-Structured Titania Arrays Fabricated Using a Simple Process

MRS Proceedings ◽

10.1557/proc-828-a7.5 ◽

2004 ◽

Vol 828 ◽

Author(s):

Zuruzi Abu Samah ◽

Andrei Kolmakov ◽

Martin Moskovits ◽

Noel C. MacDonald

Keyword(s):

Photoelectron Spectroscopy ◽

Low Cost ◽

Sol Gel ◽

X Ray Diffraction ◽

Aqueous Hydrogen Peroxide ◽

X Ray ◽

Sensing Systems ◽

Potential Applications ◽

Nano Wires ◽

Low Temperature Process

ABSTRACTUsing a novel low-temperature process, we demonstrate the facile integration of crack-free nanostructured titania (NST) as sensing elements in microsystems. Unlike conventional sol-gel methods, NST layers of interconnected nano-walls and nano-wires were formed by reacting Ti surfaces with aqueous hydrogen peroxide solution. Cracks were observed in NST layers formed on blanket Ti films but absent on arrays of patterned Ti pads below a threshold dimension. Analyses using TEM, high resolution SEM, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) reveal that NST consists of anatase TiO2 nano-crystals. NST pads were found able to detect oxygen gas of a few ppm. NST pad arrays were integrated on rigid and flexible substrates with potential applications in low cost and wearable sensing systems.

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A Simple Low-Cost Method to Prepare Lignocellulose-Based Composites for Efficient Removal of Cd(II) from Wastewater

Polymers ◽

10.3390/polym11040711 ◽

2019 ◽

Vol 11 (4) ◽

pp. 711 ◽

Cited By ~ 5

Author(s):

Yingying Wen ◽

Yong Ji ◽

Shifeng Zhang ◽

Jie Zhang ◽

Gaotang Cai

Keyword(s):

Photoelectron Spectroscopy ◽

Low Cost ◽

Agricultural Waste ◽

Value Added ◽

Particle Structure ◽

X Ray ◽

Removal Capacity ◽

Secondary Reactions ◽

Green Separation ◽

Surface Modified

The fabrication of functional lignocellulose-based materials has drawn considerable attention because it acts as a green separation/absorption material owing to its multi-porous mesostructure. In this study, a surface functionalized lignocellulose-based adsorbent for the highly efficient capture of Cd(II) ions was prepared through facile in situ co-deposition of wood waste-derived saw powder (SP) in the presence of tannic acid (TA) and aminopropyltriethoxysilane (APTES) mixed aqueous solution. The SP was first modified using TA-APTES coating to synthesize the functional SP substrate (SP-(TA-APTES)). The SP-(TA-APTES) hybrids served as reactive platforms, which enabled further decoration with amino-rich polyethylenimine (PEI) due to the outstanding secondary reactions of the TA-APTES layer. The surface morphology of the resulting SP-(TA-APTES)-PEI (SP-TAPI) composites were investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Significantly, the combined advantages of the lignocellulosic skeleton, the layer-particle structure, and the hybrid coating contributed to the enhanced adsorption capacity of Cd(II) (up to 22.66 mg/g at pH = 5.0). This removal capacity was higher than that of most reported agricultural waste-based or lignocellulose-based materials. The Cd(II) adsorption mechanism of the surface-modified SP-TAPI composites was studied in detail. These results provide new insights into the high value-added utilization of agricultural waste for water purification applications.

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