A platform for chemical modification of mandelate racemase: characterization of the C92S/C264S and γ-thialysine 166 variants

Sulfur-impregnated zeolite has been obtained from the natural zeolite clinoptilolite by chemical modification with Na2S at 150 °C. The purpose of zeolite impregnation was to enhance the sorption of Hg(II) from aqueous solutions. Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pHo values, zeta potential, cation-exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry with derivative thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of natural and sulfur-impregnated zeolites. Results revealed that the surface of the natural zeolite was successfully impregnated with sulfur species in the form of FeS and CaS. Chemical modification caused an increase in basicity and the net negative surface charge due to an increase in oxygen-containing functional groups as well as a decrease in specific surface area and crystallinity due to the formation of sulfur-containing clusters at the zeolite surface. The sorption of Hg(II) species onto the sulfur-impregnated zeolite was affected by the pH, solid/liquid ratio, initial Hg(II) concentration, and contact time. The optimal sorption conditions were determined as pH 2, a solid/liquid ratio of 10 g/L, and a contact time of 800 min. The maximum obtained sorption capacity of the sulfur-impregnated zeolite toward Hg(II) was 1.02 mmol/g. The sorption mechanism of Hg(II) onto the sulfur-impregnated zeolite involves electrostatic attraction, ion exchange, and surface complexation, accompanied by co-precipitation of Hg(II) in the form of HgS. It was found that sulfur-impregnation enhanced the sorption of Hg(II) by 3.6 times compared to the natural zeolite. The leaching test indicated the retention of Hg(II) in the zeolite structure over a wide pH range, making this sulfur-impregnated sorbent a promising material for the remediation of a mercury-polluted environment.

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Materials characterization of TiO2 nanotubes decorated by Au nanoparticles for photoelectrochemical applications

RSC Advances ◽

10.1039/d1ra07443a ◽

2021 ◽

Vol 11 (61) ◽

pp. 38727-38738

Author(s):

Marcin Pisarek ◽

Mirosław Krawczyk ◽

Andrzej Kosiński ◽

Marcin Hołdyński ◽

Mariusz Andrzejczuk ◽

...

Keyword(s):

Chemical Modification ◽

Tio2 Nanotubes ◽

Au Nanoparticles ◽

Materials Characterization ◽

Analytical Measurements

The structural and chemical modification of TiO2 NTs by the deposition of a well-controlled Au deposit (0.01 mg cm−1) was investigated using a combination of microscopic (SEM, STEM), analytical measurements (XPS, SERS, UV-Vis, XRD) and photoelectrochemical investigations.

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Characterization of Surfaces on Poly(vinyl acetate) by the Chemical Modification X-ray Photoelectron Spectroscopy. Mechanisms of Fluorescence on the Poly(vinyl acetate) Irradiated with Laser.

KOBUNSHI RONBUNSHU ◽

10.1295/koron.59.69 ◽

2002 ◽

Vol 59 (2) ◽

pp. 69-73 ◽

Cited By ~ 1

Author(s):

Mitsuho MAEDA ◽

Yasushi OZAKI ◽

Keiji NISHIUCHI

Keyword(s):

Chemical Modification ◽

Vinyl Acetate ◽

Photoelectron Spectroscopy ◽

X Ray

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Preparation and Characterization of Chemically-Modified Biomaterials and Their Application as Adsorbents of Penicillin G

Clean Technologies ◽

10.3390/cleantechnol1010008 ◽

2018 ◽

Vol 1 (1) ◽

pp. 114-124 ◽

Cited By ~ 2

Author(s):

Jesie Silva ◽

Lizebel Morante ◽

Tesfamichael Demeke ◽

Jacqueline Baah-Twum ◽

Abel Navarro

Keyword(s):

Chemical Modification ◽

Functional Groups ◽

Negative Impact ◽

Ph Dependence ◽

Sem Analysis ◽

Penicillin G ◽

Tea Leaves ◽

Reaction Conditions ◽

Spent Tea Leaves

The prevalence of antibiotics in water creates microbial resistance and has a negative impact on the ecosystem. Biomaterials such as spent tea leaves are rich in functional groups and are suitable for chemical modification for diverse applications. This research proposes the use of spent tea leaves of chamomile (CM), green tea (GT), and peppermint (PM) as structural scaffolds for the incorporation of carboxyl, sulfonyl, and thiol groups to improve the adsorption of Penicillin G (Pe). Adsorbents characterization reported a higher number of acidic functional groups, mainly in thiolated products. Scanning electron microscopy (SEM) analysis showed changes on the surfaces of the adsorbents due to reaction conditions, with a stronger effect on thiolated and sulfonated adsorbents. Elemental analysis by Energy dispersive X-ray spectrophotometry (EDS) corroborated the chemical modification by the presence of sulfur atoms and the increase in oxygen/carbon ratios. Batch experiments at different pH shows a strong pH-dependence with a high adsorption at pH 8 for all the adsorbents. The adsorption follows the trend CMs > GTs > PMs. Thiolation and sulfonation reported higher adsorptions, which is most likely due to the sulfur bridge formation, reaching adsorption percentages of 25%. These results create a new mindset in the use of spent tea leaves and their chemical modifications for the bioremediation of antibiotics.

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Selective chemical modification and mass spectrometric peptide mapping: A new approach for the molecular characterization of surface topology and micro-environment in protein tertiary structures

Peptides 1992 ◽

10.1007/978-94-011-1470-7_26 ◽

1993 ◽

pp. 83-84 ◽

Cited By ~ 3

Author(s):

M. Przybylski ◽

C. Borchers ◽

D. Suckau ◽

M. Mak ◽

M. Jetschke

Keyword(s):

Chemical Modification ◽

Molecular Characterization ◽

Peptide Mapping ◽

Mass Spectrometric ◽

Surface Topology ◽

Tertiary Structures ◽

New Approach ◽

Selective Chemical

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Sulfonation and Characterization of Tert-Butyl Styrene/Styrene/Isoprene Copolymer and Polypropylene Blends for Blood Compatibility Applications

Polymers ◽

10.3390/polym12061351 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1351

Author(s):

Bin-Hong Tsai ◽

Yung-Han Chuang ◽

Chi-Hui Cheng ◽

Jui-Che Lin

Keyword(s):

Block Copolymers ◽

Chemical Modification ◽

Blood Compatibility ◽

Blood Platelet ◽

Mineral Oil ◽

Tert Butyl ◽

Hydrophobic Nature ◽

Polypropylene Blends ◽

Uv Ozone

Hydrogenated styrenic block copolymers (HSBCs) have been used in medical tubing for many years due to their high clarity, flexibility, kink resistance, and toughness. However, when it comes to blood storage applications, HSBC compounds’ market has been limited because of their high hydrophobicity, which may trigger platelet adhesion when contacting with blood. HSBC needs to be physically or chemically modified in advance to make it blood compatible; however, HSBC has strong UV/ozone resistance, thermooxidative stability, and excellent processing capability, which increases the difficulty of the chemical modification process as unsaturated dienes has been converted to saturated stable midblocks. Moreover, medical HSBC-containing compounds primarily make up with the non-polar, hydrophobic nature and benign characteristics of other common ingredients (U.S. Pharmacopeia (USP) grades of mineral oil and polypropylene), which complicates the realization of using HSBC-containing compounds in blood-contacting applications, and this explains why few studies had disclosed chemical modification for biocompatibility improvement on HSBC-containing compounds. Sulfonation has been reported as an effective way to improve the material’s blood/platelet compatibility. In this study, hydrogenated tert-butyl styrene (tBS)-styrene-isoprene block copolymers were synthesized and its blends with polypropylene and USP grades of mineral oil were selectively sulfonated by reaction with acetyl sulfate. By controlling the ratio of the hydrogenated tBS-styrene-isoprene block copolymer in the blend, sulfonated films were optimized to demonstrate sufficient physical integrity in water as well as thermal stability, hydrophilicity, and platelet compatibility.

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