High Isoelectric Point Research Articles

Designing mixed cationic/anionic supports to covalently immobilize/stabilize enzymes with high isoelectric point by enzyme adsorption and support-enzyme glutaraldehyde crosslinking

Ficin fully immobilized on Asp-agarose beads at pH 7 but not on an aminated support. This made enzyme adsorption plus glutaraldehyde modification non-viable for this enzyme. Modifying glyoxyl-agarose beads with mixtures of Asp and 1,6-hexamethylenediamine (HA) at different ratios, mixed anion/cation exchanger supports were built. Only if HA greatly exceed Asp in the support, immobilization did not work. While only using the Asp-agarose support immobilized enzyme molecules were only ionically adsorbed after glutaraldehyde treatment (visualized in SDS-PAGE analysis), the mixed supports gave covalent immobilization. The glutaraldehyde modification of these biocatalysts permitted to establish covalent bonds with the support, and this was more effective when using higher amounts of HA in the support. When around 60 % of the groups in the support were HA, the treatment with glutaraldehyde fully suppressed enzyme release from the support after boiling in SDS. The glutaraldehyde treated biocatalysts were more stable than just the adsorbed enzymes or the enzyme adsorbed only on Asp supports and then treated with glutaraldehyde (the optimal biocatalyst retained 90 % of the initial activity while the just adsorbed ficin retained 50 % of the initial activity). This strategy can be utilized to immobilize other proteins with high isoelectric points following this immobilization strategy.

Plant-based marbled salami analogs: Emulsion-loaded microgels embedded within protein-polysaccharide hydrogel matrices

The inherent molecular differences between plant and animal proteins make it challenging to accurately simulate the optical and mechanical properties of real meat products using plant-derived ingredients. Soft matter physics approaches are therefore being employed to direct the assembly of plant proteins, polysaccharides, and lipids into meat-like structures. The main focus of the current study was to use soft matter physics approaches to create plant-based analogs of marbled meat products, such as salami, chorizo, or pepperoni. These products have whitish fatty regions embedded within reddish/brown lean regions. In this study, we mimicked the fatty regions in salami using emulsion-loaded alginate beads and the lean regions using composite hydrogels assembled from potato protein and gellan gum. Initially, the textural attributes of the plant-based lean regions were optimized by varying potato protein type (low or high isoelectric point) and concentration. As expected, the mechanical strength of the lean region analogs increased with increasing protein content and depended on protein type. Introducing alginate beads into the salami analogs had little impact on their textural attributes when measured under compression conditions but decreased their stiffness and fracture stress when measured under tensile conditions. In particular, introducing either small or large beads reduced the stiffness and breaking stress of the salami analogs, which was attributed to the introduction of weak points in the composite hydrogel. Finally, we showed that the appearance and textural attributes of real salami could be mimicked in plant-based salami by optimizing its composition and structure. This research provides valuable insights into methods of better simulating the properties of marbled meat products, like sausages and cold-cut meat products, thereby creating a more sustainable food supply.

Lysine methylation: A strategy to improve in-cell NMR spectroscopy of proteins

BackgroundIn-cell NMR is a valuable technique for investigating protein structure and function in cellular environments. However, challenges arise due to highly crowded cellular environment, where nonspecific interactions between the target protein and other cellular components can lead to signals broadening or disappearance in NMR spectra. ResultsWe implemented chemical reduction methylation to selectively modify lysine residues on protein surfaces aiming to weaken charge interactions and recover obscured NMR signals. This method was tested on six proteins varying in molecular size and lysine content. While methylation did not disrupt the protein's native conformation, it successful restored some previously obscured in-cell NMR signals, particularly for proteins with high isoelectric points that decreased post-methylation. SignificanceThis study affirms lysine methylation as a feasible approach to enhance the sensitivity of in-cell NMR spectra for protein studies. By mitigating signal loss due to nonspecific interactions, this method expands the utility of in-cell NMR for investigating proteins in their natural cellular environment, potentially leading to more accurate structural and functional insights.

Revealing the Limitation Induced by Hydroxyl in Regulating Solvation Structure of Zn2+ and Overcoming Challenges with Hybrid Additives towards Highly StableZinc Anodes.

In the field of electrolyte design for aqueous zinc-ion batteries (AZIBs), additives containing hydroxyl have been demonstrated to effectively modulate the solvation structure of Zn2+. However, reported studies typically focus solely on the effectiveness of hydroxyl while neglecting the issues that emerge during solvation structure regulation. The strong electron-attracting capability of Zn2+ attracts electrons from the oxygen in hydroxyl, thereby weakening the strength of hydroxyl, the hydrogen evolution reaction (HER) is also pronounced. This work innovatively reveals the limitation of hydroxyl-containing additives and proposes a synergistic regulation strategy based on hybrid additives. Arginine with a high isoelectric point is introduced into the electrolyte system containing hydroxyl additives. The protonation effect and electrostatic attraction of arginine enable it to absorb protons at the anode released by the weakened hydroxyl, thereby compensating for the limitation of hydroxyl additives. Under the synergistic action of hybrid additives, the Zn|Zn battery achieved stable deposition/stripping for over 1200 hours under 10 mA cm-2 and 10 mAh cm-2. Moreover, the Zn|Cu battery cycled for over 570 hours with a high Coulombic efficiency of 99.82%. This study presents a pioneering perspective for the further application of AZIBs.

Development and Characterization of Hybrid Meat Analogs from Whey Protein-Mushroom Composite Hydrogels.

There is a need to reduce the proportion of animal-derived food products in the human diet for sustainability and environmental reasons. However, it is also important that a transition away from animal-derived foods does not lead to any adverse nutritional effects. In this study, the potential of blending whey protein isolate (WPI) with either shiitake mushroom (SM) or oyster mushroom (OM) to create hybrid foods with enhanced nutritional and physicochemical properties was investigated. The impact of OM or SM addition on the formation, microstructure, and physicochemical attributes of heat-set whey protein gels was therefore examined. The mushroom powders were used because they have relatively high levels of vitamins, minerals, phytochemicals, and dietary fibers, which may provide nutritional benefits, whereas the WPI was used to provide protein and good thermal gelation properties. A variety of analytical methods were used to characterize the structural and physicochemical properties of the WPI-mushroom hybrids, including confocal microscopy, particle electrophoresis, light scattering, proximate analysis, differential scanning calorimetry, thermogravimetric analysis, dynamic shear rheology, textural profile analysis, and colorimetry. The charge on whey proteins and mushroom particles went from positive to negative when the pH was raised from 3 to 9, but whey protein had a higher isoelectric point and charge magnitude. OM slightly increased the thermal stability of WPI, but SM had little effect. Both mushroom types decreased the lightness and increased the brownness of the whey protein gels. The addition of the mushroom powders also decreased the hardness and Young's modulus of the whey protein gels, which may be because the mushroom particles acted as soft fillers. This study provides valuable insights into the formation of hybrid whey protein-mushroom products that have desirable physiochemical and nutritional attributes.

Towards monitoring of critical illness via the detection of histones with extended gate field-effect transistor sensors

Extracellular histone proteins in the blood indicate a heightened risk of morbidity after trauma or in major illnesses such as sepsis. We present the development of an aptasensor for histone detection with an extended gate field-effect transistor (EGFET) configuration, which benefits from low power consumption, rapid response, and compatibility with miniaturized gold electrodes. Histones have a high isoelectric point and charge density, which cause them to physically adsorb to non-specific elements of the sensor that have available electrostatic charges. To combat this, the sensing surface is formed with a thiol-modified, high-affinity and histone-specific RNA aptamer sequence and by co-immobilizing with poly(ethylene glycol) methyl ether thiol (PEG) as a blocking agent. Surface plasmon resonance (SPR) is used to analyze aptamer and PEG immobilization strategies, confirm histone binding, and calculate kinetic binding constants. Through comparison of different blocking agents and time-dependent preparation, the ideal equilibrium dissociation constant (KD) is estimated to be below 200 pM, which is the upper range of extracellular histone concentrations in critically ill patients with high mortality. The EGFET sensitivity of the optimized aptasensor is 6.65 mV/decade concentration change for histone H4 with a physiologically relevant 5 pM limit of detection. Selectivity tests with 100 nM bovine serum albumin (BSA) demonstrate a signal response that is 13-fold smaller than for histones. This EGFET aptasensor platform is suitable for future point-of-care monitoring of histone levels in critically ill patients, thus permitting the early detection of increased risk and the need for more aggressive interventional measures to prevent mortality.

Antibacterial activity of lysozyme after association with carboxymethyl konjac glucomannan

The unique high isoelectric point of lysozyme (LYZ) restricts its application in composite antibacterial coating due to the unfavorable liability to electrostatic interaction with other components. In this work, the antibacterial activity of a dispersible LYZ–carboxymethyl konjac glucomannan (CMKGM) polyelectrolyte complex was evaluated. Kinetic analysis revealed that, compared with free LYZ, the complexed enzyme exhibited decreased affinity (Km) but markedly increased Vmax against Micrococcus lysodeikticus, and QCM and dynamic light scattering analysis confirmed that the complex could bind with the substrate but in a much lower ratio. The complexation with CMKGM did not alter the antibacterial spectrum of LYZ, and the complex exerted antibacterial function by delaying the logarithmic growth phase and impairing the cell integrity of Staphylococcus aureus. Since the LYZ–CMKGM complex is dispersible in water and could be assembled easily, it has great potential as an edible coating in food preservation.

Identification of potential C1-binding sites in the immunoglobulin CL domains.

Immunoglobulin G (IgG) molecules that bind antigens on the membrane of target cells spontaneously form hexameric rings, thus recruiting C1 to initiate the complement pathway. However, our previous report indicated that a mouse IgG mutant lacking the Cγ1 domain activates the pathway independently of antigen presence through its monomeric interaction with C1q via the CL domain, as well as Fc. In this study, we investigated the potential interaction between C1q and human CL isoforms. Quantitative single-molecule observations using high-speed atomic force microscopy revealed that human Cκ exhibited comparable C1q binding capabilities with its mouse counterpart, surpassing the Cλ types, which have a higher isoelectric point than the Cκ domains. Nuclear magnetic resonance and mutation experiments indicated that the human and mouse Cκ domains share a common primary binding site for C1q, centred on Glu194, a residue conserved in the Cκ domains but absent in the Cλ domains. Additionally, the Cγ1 domain, with its high isoelectric point, can cause electrostatic repulsion to the C1q head and impede the C1q-interaction adjustability of the Cκ domain in Fab. The removal of the Cγ1 domain is considered to eliminate these factors and thus promote Cκ interaction with C1q with the potential risk of uncontrolled activation of the complement pathway in vivo in the absence of antigen. However, this research underscores the presence of potential subsites in Fab for C1q binding, offering promising targets for antibody engineering to refine therapeutic antibody design.

Genome-Wide Analysis and Characterization of FBA (Fructose 1,6-bisphosphate aldolase) Gene Family of Phaseolus vulgaris L

Fructose-1,6-biphosphate aldolase (FBA) genes have important roles in plant stress responses. At the same time, these genes positively affect growth and development in plants. FBA is involved in gluconeogenesis, glycolysis, and the Calvin-Benson cycle, and it is an enzyme that plays an important role in signal transduction of these stages. This study aims to determine and characterize the FBA gene family in the bean genome. As a result of the study, 7 Pvul-FBA genes were determined in the bean (Phaseolus vulgaris L.) genome. The highest amino acid number of Pvul-FBA proteins was determined in the Pvul-FBA-1 gene (1374), and the highest molecular weight (43.03 kDa) was determined in the Pvul-FBA-7 gene. Again, the highest isoelectric point (8.03) was determined in the Pvul-FBA-3 gene. It has been determined that the Pvul-FBA-6/Pvul-FBA-7 genes are segmental duplicated genes. The main four groups were obtained according to the phylogenetic analysis consisting of FBA proteins of three plants (P. vulgaris, Glycine max, and Arabidopsis thaliana). As a result of interproscan analysis, Motif-1, 2, 3, 4 and 5 were found to contain the fructose-bisphosphate aldolase domain. According to in silico gene expression analysis, it was determined that the expression rates of Pvul-FBA genes increased or decreased under salt and drought stress conditions. Synteny analyses of FBA genes in common bean and A. thaliana plants showed that these three plants have a relationship in terms of FBA genes. The results of this research will allow a better designation of the molecular structure of the FBA gene family in common bean.

DnaK duplication and specialization in bacteria correlates with increased proteome complexity.

The chaperone 70 kDa heat shock protein (Hsp70) is important for cells from bacteria to humans to maintain proteostasis, and all eukaryotes and several prokaryotes encode Hsp70 paralogs. Although the mechanisms of Hsp70 function have been clearly illuminated, the function and evolution of Hsp70 paralogs is not well studied. DnaK is a highly conserved bacterial Hsp70 family. Here, we show that dnaK is present in 98.9% of bacterial genomes, and 6.4% of them possess two or more DnaK paralogs. We found that the duplication of dnaK is positively correlated with an increase in proteomic complexity (proteome size, number of domains). We identified the interactomes of the two DnaK paralogs of Myxococcus xanthus DK1622 (MxDnaKs), which revealed that they are mostly nonoverlapping, although both prefer α and β domain proteins. Consistent with the entire M. xanthus proteome, MxDnaK substrates have both significantly more multi-domain proteins and a higher isoelectric point than that of Escherichia coli, which encodes a single DnaK homolog. MxDnaK1 is transcriptionally upregulated in response to heat shock and prefers to bind cytosolic proteins, while MxDnaK2 is downregulated by heat shock and is more associated with membrane proteins. Using domain swapping, we show that the nucleotide-binding domain and the substrate-binding β domain are responsible for the significant differences in DnaK interactomes, and the nucleotide binding domain also determines the dimerization of MxDnaK2, but not MxDnaK1. Our work suggests that bacterial DnaK has been duplicated in order to deal with a more complex proteome, and that this allows evolution of distinct domains to deal with different subsets of target proteins.IMPORTANCEAll eukaryotic and ~40% of prokaryotic species encode multiple 70 kDa heat shock protein (Hsp70) homologs with similar but diversified functions. Here, we show that duplication of canonical Hsp70 (DnaK in prokaryotes) correlates with increasing proteomic complexity and evolution of particular regions of the protein. Using the Myxococcus xanthus DnaK duplicates as a case, we found that their substrate spectrums are mostly nonoverlapping, and are both consistent to that of Escherichia coli DnaK in structural and molecular characteristics, but show differential enrichment of membrane proteins. Domain/region swapping demonstrated that the nucleotide-binding domain and the β substrate-binding domain (SBDβ), but not the SBDα or disordered C-terminal tail region, are responsible for this functional divergence. This work provides the first direct evidence for regional evolution of DnaK paralogs.

Degradation of bisphenol F by peroxymonosulfate activated with palladium-based catalysts

In this study, supported Pd catalysts were prepared and used as heterogeneous catalysts for the activation of peroxymonosulfate (PMS) which successfully degrade bisphenol F (BPF). Among the supported catalysts (i.e., Pd/SiO2, Pd/CeO2, Pd/TiO2 and Pd/Al2O3), Pd/TiO2 exhibited the highest catalytic activity due to the high isoelectric point and high Pd0 content. Pd/TiO2 prepared by the deposition method leads to high Pd dispersion, which are the key factors for efficient BPF degradation. The influencing factors were investigated during the reaction process and two possible degradation pathways were proposed. Density functional theory (DFT) calculations demonstrate that stronger BPF adsorption and BPF degradation with lower reaction barrier occurs on smaller Pd particles. The catalytic activities are strongly dependent on the structural features of the catalysts. Both experiments and theoretical calculations prove that the reaction is actuated by electron transfer rather than radicals.

Grafting modification of thin-film composite membrane with quaternary ammonium polyelectrolyte for Mg2+/Li+ separation

The positively charged nanofiltration membrane (NF) has a strong repulsive effect on divalent magnesium ions, thus could be applied for the separation of Mg2+/Li+. Chemical grafting modification is an effective way to prepare positively charged membranes. However, it is difficult to achieve chemical modification on the surface of polyamide membrane as the chemical stability of polyamide. By introducing hydroxyl rich monomers (3-[n-tris(hydroxymethyl)methylamino]−2-hydroxypropanesulfonic, HMAH) as active sites in the interfacial polymerization process, the olefin monomers containing quaternary ammonium salt functional groups (acryloxyethyl trimethyl ammonium chloride, ATA) were reacted onto the surface of NF membrane through radical polymerization initiated by cerium ions to obtain positively charged NF membrane. The successful grafting reaction of quaternary ammonium salt monomer onto the surface of NF membrane was verified by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The membrane with dense and smooth surface layer showed C-N+ characteristic peak in XPS N1s spectra and high isoelectric point. Meanwhile, the as-prepared membrane achieved high MgCl2 rejection of 95.74% and low LiCl rejection of 18.1%, with pure water permeance of 9.43 L·m−2·h−1·bar−1. After 60 hours of mixture filtration experiment, the membrane exhibited good long-term stability, maintaining the ionic separation selectivity over 30, which indicated that the positively charged membrane prepared by grafting method has potential application in the separation of Mg2+/Li+.

Fabrication and characterization of nanoparticles with lecithin liposomes and poloxamer micelles: Impact of conformational structures of poloxamers

In this study, we fabricated and characterized nanoparticles with a core/shell structure using lecithin and poloxamer. We also evaluated their ability to load proteins. At a lecithin/poloxamer ratio of 0.2, the sizes of lecithin/P188 (low molecular weight poloxamer) and lecithin/P338 (high molecular weight poloxamer) nanoparticles were 316.1 and 280.7 nm, respectively. Lecithin/P188 nanoparticles easily lost core/shell structure at pH 3 and 7. Lecithin/P338 nanoparticles were stable at pH 7 but unstable at pH 3. Only lecithin/P338 nanoparticles exhibited stability in response to temperature changes, despite an increase in their size with decreasing temperature. Loading a model protein with a high isoelectric point (pI) in liposome/poloxamer nanoparticles seemed impossible. A model protein with low pI was efficiently loaded in lecithin/poloxamer nanoparticles, and the maximum loading capacity of lecithin/P188 and lecithin/P338 nanoparticles was 14.85 and 42.34 mg/g particle, respectively. However, lecithin/P188 nanoparticles loading this model protein lost their core/shell structure.

PH-Swing membrane adsorption of perfluoroalkyl substances: Anion-exchange brushes and role of water chemistry

The pH-swing membrane adsorption, aiming for effective removal, high membrane permeability, and facile regeneration, was developed to remediate emerging perfluoroalkyl contaminants. Compared to the collapse transformation of deprotonated tertiary-amine brushes at neutral pH (pKb: ∼5.82), the quaternary-ammonium (QA) brushes endowed consistent membrane pore structure and higher isoelectric point (pHIEP: 11.2 versus 7.5), resulting in a suitable pH-swing adsorption/desorption range towards groundwater conditions. Such QA-grafted membranes (QA loading: 1.1 mmol/g) not only presented >90 % removal of perfluorooctanoic acid (PFOA) at a treatment capacity of 570 L per m2 of membrane area, but also enabled effective membrane regeneration that >97 % desorption was achieved at pH 12.5 and 5 % methanol. The remediation is driven by synergetic electrostatic and hydrophobic interactions, as demonstrated by (1) the zeta-potential dependent removal performance and (2) the greater maximum adsorption capacity towards the more hydrophobic perfluorooctane sulfonate than PFOA (Qm: 0.65 mmol/g and 0.44 mmol/g, respectively). Within three pH-swing adsorption/regeneration cycles, a total PFOA removal of 82.4 % was achieved with a treatment capacity of 2,930 L/m2. The impacts of ionic strength, ionic types, and natural organic matters were evaluated. Overall, the pH-swing strategy is an effective method with high permeability (165.6 L m−2h−1bar−1), stability, and tunable adsorption/regeneration processes.

A highly carboxylated sponge-like material: preparation, characterization and protein adsorption

Producing of high-purity protein products using separation materials is critical to the biopharmaceutical industry. Efforts to achieve protein adsorption materials with large adsorption capacity and high processing efficiency have been challenging. Herein, a highly carboxylated sponge-like monolithic adsorbent material was prepared by using SiO2 nanofibers as a rigid support framework, and esterification crosslinking reactants with polyvinyl alcohol (PVA)/polymeric carboxylic acid (polyacrylic acid, PAA) as a functional organic binder, which were modified in situ on the nanofiber framework. The obtained PVA/PAA sponge-like monolithic adsorbent material (PVA/PAA SMAM) exhibits a porous structure and possesses mechanical stability and recoverability of underwater compression. The high porosity provides more sites for carboxyl groups, making PVA/PAA SMAM rich in carboxyl groups. Experiments showed that PVA/PAA SMAM selectively adsorbes proteins with high isoelectric points. Using Cytochrome C (Cyt-C) as the main model protein with a high isoelectric point, the maximum adsorption of Cyt-C by the PVA/PAA SMAM at pH = 9 was 3079.3 mg/g with a rapid equilibration time (40 min), which is clearly superior to the currently reported Metal-organic frame structure (MOF) composites for Cyt-C adsorption. The isothermal adsorption model for the Cyt-C adsorption of the PVA/PAA SMAM material agrees well with the Freundlich adsorption model and the quasi-first kinetic model. Excellent mechanical and chemical structural stability endow the PVA/PAA SMAM material with protein elution capacity and good reusability, and secondary structure of the protein after elution was unchanged. Subsequently, selective adsorption and separation of Cyt-C from porcine heart supernatant was successfully achieved with PVA/PAASMAM material. This work provides new materials with excellent performance for various bio-separation applications.

De novo transcriptome of a bast fibre crop Crotalaria juncea reveals T2 ribonuclease genes to investigate late-acting self-rejection of pollens

The biology of gametophytic late-acting self-rejection of pollen in pre-zygotic ovules is relatively unknown in the Fabaceae family of plants. Our understanding of the genetic basis of late-acting self-incompatibility (LSI) is limited due to a lack of sequence data and candidate genes. Crotalaria juncea, a Fabaceae family member that produces commercially important phloem fiber, possesses LSI. Due to a lack of selfed seeds, it is difficult to maintain genetic purity in germplasm and develop breeding lines for improved fiber quality and yield. To investigate candidate genes for LSI in C. juncea, a high-quality de novo transcriptome was generated. It facilitated the identification of genes from the self-incompatibility-related ribonuclease (RNase) family, specifically a Class III T2/RNase gene with sequence properties similar to S-RNase proteins. Based on conserved amino acid motifs, histidine residues, and a high isoelectric point (pI ≥9.0), Cjun_RNS3.1 was identified as an S-RNase homologue (non-S-RNase) or relic S-RNase gene. Unlike typical S-RNases found in known SI plant systems, evolutionary analysis of the Cjun_RNS3.1 protein revealed its ancestral origin. The expression of Cjun_RNS3.1 and other T2/RNase genes revealed differential expression patterns in the pistils of LSI and self-compatible Crotalaria species. The upregulation of the Cjun_RNS3.1 gene during the different stages of pollen tube development indicates that it may be involved in the LSI. In summary, the sunn hemp transcriptome is the first genomic resource reported from a Fabaceae family plant with the LSI trait. A non-S-RNase gene with an ancestral evolutionary origin and a diverse function was found, which could be related to gametophytic LSI. This could be used as a model system to investigate the molecular basis of LSI in the Fabaceae family and help develop C. juncea breeding lines for fibre improvement.

Recent Advances, Challenges, and Future Perspectives of ZnO Nanostructure Materials Towards Energy Applications.

In this approach, zinc oxide (ZnO) is a multipurpose substance with remarkable characteristics such as high sensitivity, a large specific area, non-toxicity, excellent compatibility, and a high isoelectric point, which make it attractive for discussion with some limitations. It is the most favorable possible option for the collection of nanostructures in terms of structure and their characteristics. The development of numerous ZnO nanostructure-based electrochemical sensors and biosensors used in health diagnosis, pharmaceutical evaluation, food hygiene, and contamination of the environment monitoring is described, as well as the production of ZnO nanostructures. Nanostructured ZnO has good chemical and temperature durability as an n-type semiconducting material, making it useful in a wide range of uses, from luminous materials to supercapacitors, batteries, solar cells, photocatalysis, biosensors, medicinal devices, and more. When compared to the bulk materials, the nanosized materials have both a higher rate of disintegration and a higher solubility. Furthermore, ZnO nanoparticles are regarded as top contenders for electrochemical sensors due to their strong electrochemical behaviors and electron transmission characteristics. The impact of many factors, including selectivity, sensitivity, detection limit, strength, and structures, arrangements, and their respective functioning processes, has been investigated. This study concentrated a substantial amount of its attention on the recent advancements that have been made in ZnO-based nanoparticles, composites, and modified materials for use in the application areas of energy storage and conversion devices as well as biological applications. Supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, medicinal, and biological systems have been studied. ZnO-based materials are constantly analyzed for their advantages in energy and life science applications.

Efficient removal of antimony from aqueous solution using Al-doped Fe3O4 nanoparticles: adsorption behavior and kinetics study

ABSTRACT Fe3O4 magnetic nanoparticles have been employed as a cost-effective adsorbent for removing Sb from aqueous solutions. However, the widespread application is limited by its finite adsorption capacity and aggregation nature. In this study, Al-doped Fe3O4 nanoparticles were prepared via a facile solvothermal method to break through the current obstacle. Al-doped Fe3O4 nanoparticles were fully characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning Electron microscopy (SEM), and infrared spectroscopy (FTIR). The results confirmed that Al atoms had been successfully doped into Fe3O4 crystal unit cells, resulting in smaller particle size, larger surface area, and higher isoelectric point. These changes led to the formation of more hydroxyl groups on the surface of Al-doped Fe3O4 nanoparticles. Compared to pristine Fe3O4, the maximum adsorption capacity toward Sb(III) and Sb(V) increased from 111.695 to 197.034 mg/g and from 34.479 to 187.459 mg/g at neutral pH, respectively. The doping of Al also had some negative impact on the original magnetic strength but still maintained a sufficient magnetic separation potential. These results indicated that Al-doped Fe3O4 nanoparticles could be employed as a promising adsorbent for removing Sb(III) and Sb(V) from wastewater.

Ultra-fast photocatalytic degradation and seed germination of band gap tunable nickel doping ceria nanoparticles

Doping transition metal ions into cerium oxide (CeO2) results in interesting modifications to the material, including an increase in surface area, a high isoelectric point, biocompatibility, greater ionic conductivity, and catalytic activity. Herein, various concentrations (1–5%, 10% and 20%) of nickel (Ni) doped CeO2 nanoparticle have been made by a facile chemical process. Using a variety of cutting-edge analytical techniques, the structural, optical, and photocatalytic properties of undoped and varied concentrations (1–5%, 10%, and 20%) of Ni doped CeO2 nanoparticles have been investigated. Pure cubic fluorite structure with average crystallite sizes in the region of 12–15 nm was determined by X-ray diffraction (XRD) investigation. Transmission electron microscopy (TEM), which revealed highly homogeneous hexagonal shape of the particles with average size of 15 nm, was also used to determine microstructural information. According to the optical absorption, the band gaps of Ni doped and undoped CeO2 nanoparticles were found to be 2.96 eV and 1.95 eV, respectively. When exposed to sunlight, the narrow band gap Ni doped CeO2 nanoparticles worked as an active visible light catalyst to remove the dyes Rose Bengal (RB) and Direct Yellow (DY). The best photodegradation efficiencies for RB and DY dyes were found about 93% and 97%, respectively, using the 5% Ni-doped CeO2 catalyst. The apparent rate constant values of 0.039 for RB and 0.040 min−1 were attained for DY. As well, the treated, untreated dye solution and control solutions were utilized to assess the toxicity of commercially accessible Vigna Radiata seeds. In this study exhibits percentages of length and germination increased by 30–35% when compared to dye pollutant solution. The Ni doped CeO2 can provide a substantial alternative for current industrial waste management because of its quick photocatalytic activity and remarkable seed germination results.

Hydrogenation of HPHT nanodiamonds and their nanoscale interaction with chitosan

Hydrogenation of the surface can provide specific and unique properties to nanodiamonds. In this study, a series of high-pressure high-temperature nanodiamonds (HPHT NDs) with varying levels of hydrogenation and sp2 carbon content is prepared and characterized in terms of optical properties, structure, surface chemistry, particle size distribution, and zeta potential. The higher the surface sp2-C content and level of hydrogenation the better dispersibility in acidic to neutral pH and higher isoelectric points are achieved. We further evaluated the interaction of hydrogenated HPHT NDs with chitosan by infrared spectroscopy and atomic force microscopy. We have found that chitosan is electrostatically attracted to the hydrogenated HPHT NDs, it improves the dispersibility of the HPHT NDs with a lower level of hydrogenation, and it provides colloidal stability in the broad pH range 2–11 to all hydrogenated HPHT NDs. Finally, we demonstrate that chitosan coating enables the decoration of hydrogenated HPHT NDs by silver nanoparticles.