scholarly journals Fluorescein-Labeled Starch Maleate Nanoparticles as Sensitive Fluorescent Sensing Probes for Metal Ions

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Suk Fun Chin ◽  
Aressa Azman ◽  
Suh Cem Pang ◽  
Sing Muk Ng
Keyword(s):  
Particle Size ◽  
Metal Ions ◽  
Self Assembly ◽  
Detection Limits ◽  
Emission Wavelength ◽  
Dependent Manner ◽  
Ethanolic Solution ◽  
Concentration Dependent Manner ◽  
Maximum Emission ◽  
Fluorescent Sensing

Fluorescein 5(6)-isothiocyanate starch maleate (FISM) nanoparticles were prepared by covalently attached fluorescein 5(6)-isothiocyanate (FITC) with starch maleate. FISM nanoparticles with a mean particle size of 87 nm were formed via self-assembly upon precipitation in ethanolic solution. FISM nanoparticles were strongly fluorescent with maximum emission wavelength of 518 nm. The fluorescence of FISM nanoparticles can be quenched by silver (Ag+) and lead (Pb2+) ions in a concentration dependent manner. We have demonstrated the first use of FISM nanoparticles as cheap and effective fluorescent sensing probes for Ag+and Pb2+ions with detection limits as low as 2.55×10−5 M and 3.64×10−5 M, respectively.

scholarly journals Terminal short arm domains of basement membrane laminin are critical for its self-assembly.

1990 ◽  
Vol 110 (3) ◽  
pp. 825-832 ◽  
Author(s):  
J C Schittny ◽  
P D Yurchenco
Keyword(s):  
Self Assembly ◽  
Affinity Column ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Calcium Dependent ◽  
Domain Specific ◽  
Binding Domains ◽  
Individual Domain ◽  
The Individual

Laminin self-assembles into large polymers by a cooperative two-step calcium-dependent mechanism (Yurchenco, P. D., E. C. Tsilibary, A. S. Charonis, and H. Furthmayr. 1985. J. Biol. Chem. 260:7636-7644). The domain specificity of this process was investigated using defined proteolytically generated fragments corresponding to the NH2-terminal globule and adjacent stem of the short arm of the B1 chain (E4), a complex of the two short arms of the A and B2 chains attached to the proximal stem of a third short arm (E1'), a similar complex lacking the globular domains (P1'), and the distal half of the long arm attached to the adjacent portion of the large globule (E8). Polymerization, followed by an increase of turbidity at 360 nm in neutral isotonic TBS containing CaCl2 at 35 degrees C, was quantitatively inhibited in a concentration-dependent manner with laminin fragments E4 and E1' but not with fragments E8 and P1'. Affinity retardation chromatography was used for further characterization of the binding of laminin domains. The migration of fragment E4, but not of fragments E8 and P1', was retarded in a temperature- and calcium-dependent fashion on a laminin affinity column but not on a similar BSA column. These data are evidence that laminin fragments E4 and E1' possess essential terminal binding domains for the self-aggregation of laminin, while fragments E8 and P1' do not. Furthermore, the individual domain-specific interactions that contribute to assembly are calcium dependent and of low affinity.

scholarly journals Metal Ions in Activated Carbon Improve the Detection Efficiency of Aflatoxin-Producing Fungi

Toxins ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 140 ◽  
Author(s):  
Tadahiro Suzuki ◽  
Masatoshi Toyoda
Keyword(s):  
Activated Carbon ◽  
Metal Ions ◽  
Detection Efficiency ◽  
Trace Element Analysis ◽  
The Other ◽  
Dependent Manner ◽  
Element Analysis ◽  
Concentration Dependent Manner ◽  
Key Factor ◽  
Co Addition

Aflatoxins (AF), produced by several Aspergillus species, are visible under ultraviolet light if present in high amounts. AF detection can be improved by adding activated carbon, which enhances the observation efficiency of weakly AF-producing fungi. However, commercial activated carbon products differ in their characteristics, making it necessary to investigate which characteristics affect method reproducibility. Herein, the addition of 10 activated carbon products resulted in different AF production rates in each case. The differences in the production of aflatoxin G1 (AFG1) were roughly correlated to the observation efficiency in the plate culture. Trace element analysis showed that the concentrations of several metal ions differed by factors of >100, and the carbons that most effectively increased AFG1 production contained higher amounts of metal ions. Adding 5 mg L−1 Fe or Mg ions increased AFG1 production even without activated carbon. Furthermore, co-addition of both ions increased AFG1 production stably with the addition of carbon. When varying the concentration of additives, only AFG1 production increased in a concentration-dependent manner, while the production of all the other AFs decreased or remained unchanged. These findings suggest that a key factor influencing AF production is the concentration of several metal ions in activated carbon and that increasing AFG1 production improves AF detectability.

Self-assembling triazolophanes: from croissants through donuts to spherical vesicles

2015 ◽  
Vol 51 (32) ◽  
pp. 6905-6908 ◽  
Author(s):  
V. Haridas ◽  
Appa Rao Sapala ◽  
Jerry P. Jasinski
Keyword(s):  
Crystal Structure ◽  
Self Assembly ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
X Ray ◽  
Self Assembling ◽  
Assembly Mechanism ◽  
Spherical Vesicles

A detailed ultramicroscopic analysis of three novel triazolophanes demonstrated a hierarchical self-assembly mechanism. These macrocycles self-assemble in a concentration dependent manner to hemi-toroids, toroids and finally to vesicles. The finding was supported by ultramicroscopy and X-ray crystal structure studies.

scholarly journals Structure of KAP1 tripartite motif identifies molecular interfaces required for retroelement silencing

2019 ◽  
Vol 116 (30) ◽  
pp. 15042-15051 ◽  
Author(s):  
Guido A. Stoll ◽  
Shun-ichiro Oda ◽  
Zheng-Shan Chong ◽  
Minmin Yu ◽  
Stephen H. McLaughlin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Coiled Coil ◽  
Structural Data ◽  
Higher Order ◽  
Significant Loss ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Krab Domain ◽  
Genome Damage ◽  
Tripartite Motif

Transcription of transposable elements is tightly regulated to prevent genome damage. KRAB domain-containing zinc finger proteins (KRAB-ZFPs) and KRAB-associated protein 1 (KAP1/TRIM28) play a key role in regulating retrotransposons. KRAB-ZFPs recognize specific retrotransposon sequences and recruit KAP1, inducing the assembly of an epigenetic silencing complex, with chromatin remodeling activities that repress transcription of the targeted retrotransposon and adjacent genes. Our biophysical and structural data show that the tripartite motif (TRIM) of KAP1 forms antiparallel dimers, which further assemble into tetramers and higher-order oligomers in a concentration-dependent manner. Structure-based mutations in the B-box 1 domain prevent higher-order oligomerization without significant loss of retrotransposon silencing activity, indicating that, in contrast to other TRIM-family proteins, self-assembly is not essential for KAP1 function. The crystal structure of the KAP1 TRIM dimer identifies the KRAB domain binding site in the coiled-coil domain near the dyad. Mutations at this site abolished KRAB binding and transcriptional silencing activity of KAP1. This work identifies the interaction interfaces in the KAP1 TRIM responsible for self-association and KRAB binding and establishes their role in retrotransposon silencing.

Fluorescence chemosensor containing 4-methyl-7-coumarinyloxy, acetylhydrazono and N-phenylaza-15-crown-5 moieties for K+ and Ba2+ ions

2018 ◽  
Vol 24 (3) ◽  
pp. 141-145 ◽  
Author(s):  
Qiang Zhang ◽  
Kaifei Duan
Keyword(s):  
Metal Ions ◽  
Binding Constants ◽  
Detection Limits ◽  
Fluorescent Chemosensor ◽  
Fluorescent Sensing ◽  
Fluorescence Titration

AbstractA new aza-15-crown-5 derivative 1 bearing coumarin and hydrazone moieties was synthesized and characterized. The fluorescent sensing behavior and selectivity of 1 toward different metal ions in ethanol were investigated. There are 4-fold and 2-fold fluorescence enhancements of 1 at λem=406 nm upon addition of five equivalents of K+ and Ba2+, respectively. The fluorescence titration revealed the stoichiometry of 1:1 for 1-K+1-Ba2+ complexes and the binding constants (lgKs) of 4.11 for 1-K+ and 3.61 for 1-Ba2+. Compound 1 can be used as a fluorescent chemosensor for K+ and Ba2+ through discriminable photoresponse signals. The calculated detection limits for K+ and Ba2+ are 2.28 μm and 5.21 μm, respectively.

scholarly journals Ferrocene-Labelled Electroactive Aptamer-Based Sensors (Aptasensors) for Glycated Haemoglobin

Molecules ◽  
2021 ◽  
Vol 26 (23) ◽  
pp. 7077
Author(s):  
Xue-Qing Feng ◽  
Yi Ju ◽  
Wei-Tao Dou ◽  
Qing Li ◽  
Zhong-Gan Jin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Electrochemical Sensors ◽  
Electrochemical Impedance ◽  
Differential Pulse ◽  
Glycated Haemoglobin ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Pulse Voltammetry ◽  
Insight Into

Glycated haemoglobin (HbA1c) is a diagnostic biomarker for type 2 diabetes. Traditional analytical methods for haemoglobin (Hb) detection rely on chromatography, which requires significant instrumentation and is labour-intensive; consequently, miniaturized devices that can rapidly sense HbA1c are urgently required. With this research, we report on an aptamer-based sensor (aptasensor) for the rapid and selective electrochemical detection of HbA1c. Aptamers that specifically bind HbA1c and Hb were modified with a sulfhydryl and ferrocene group at the 3′ and 5′-end, respectively. The modified aptamers were coated through sulfhydryl-gold self-assembly onto screen printed electrodes, producing aptasensors with built in electroactivity. When haemoglobin was added to the electrodes, the current intensity of the ferrocene in the sensor system was reduced in a concentration-dependent manner as determined by differential pulse voltammetry. In addition, electrochemical impedance spectroscopy confirmed selective binding of the analytes to the aptamer-coated electrode. This research offers new insight into the development of portable electrochemical sensors for the detection of HbA1c

scholarly journals Photothermal Regenerated Fibers with Enhanced Toughness: Silk Fibroin/MoS2 Nanoparticles

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3937
Author(s):  
Jianjun Guo ◽  
Bo Yang ◽  
Qiang Ma ◽  
Sandra Senyo Fometu ◽  
Guohua Wu
Keyword(s):  
Silk Fibroin ◽  
Self Assembly ◽  
Molybdenum Sulfide ◽  
Dependent Manner ◽  
Hybrid Fibers ◽  
Concentration Dependent Manner ◽  
Good Thermal Stability ◽  
Regenerated Silk Fibroin ◽  
Mos2 Nanoparticles ◽  
Regenerated Fibers

The distinctive mechanical and photothermal properties of Molybdenum sulfide (MoS2) have the potential for improving the functionality and utilization of silk products in various sectors. This paper reports on the preparation of regenerated silk fibroin/molybdenum disulfide (RSF/MoS2) nanoparticles hybrid fiber with different MoS2 nanoparticles contents by wet spinning. The simulated sunlight test indicated that the temperature of 2 wt% RSF/MoS2 nanoparticles hybrid fibers could rise from 20.0 °C to 81.0 °C in 1 min and 98.6 °C in 10 min, exhibiting good thermal stability. It was also demonstrated that fabrics made by manual blending portrayed excellent photothermal properties. The addition of MoS2 nanoparticles could improve the toughness of hybrid fibers, which may be since the mixing of MoS2 nanoparticles hindered the self-assembly of β-sheets in RSF solution in a concentration-dependent manner because RSF/MoS2 nanoparticles hybrid fibers showed a lower β-sheet content, crystallinity, and smaller crystallite size. This study describes a new way of producing high toughness and photothermal properties fibers for multifunctional fibers’ applications.

scholarly journals Inulin nanostructures: The sweet-spot of carbohydrate self-assembly

2021 ◽  
Author(s):  
Zohar A. Arnon ◽  
Márkó Grabarics ◽  
Topaz Kreiser ◽  
Avi Raveh ◽  
Kevin Pagel ◽  
...  
Keyword(s):  
Nucleic Acids ◽  
Self Assembly ◽  
The Self ◽  
Dependent Manner ◽  
Supramolecular Architecture ◽  
Sweet Spot ◽  
Concentration Dependent Manner ◽  
Self Assembling ◽  
Spontaneous Organization

Supramolecular architecture formation by the self-assembly of proteins and nucleic acids is well studied. Yet, the spontaneous organization of oligosaccharides, the most common polymers in nature, is less explored. Here, using inulin as a model, we identify the "sweet spot" length for oligosaccharide assembly. Inulin forms discrete spheres in a concentration-dependent manner. Size-based fractionation displayed markedly different aggregation morphologies. Based on these findings, we believe that carbohydrates could become an important source for novel self-assembling materials.

scholarly journals Structure of the tripartite motif of KAP1/TRIM28 identifies molecular interfaces required for transcriptional silencing of retrotransposons

2018 ◽  
Author(s):  
Guido A. Stoll ◽  
Shun-ichiro Oda ◽  
Zheng-Shan Chong ◽  
Minmin Yu ◽  
Stephen H. McLaughlin ◽  
...  
Keyword(s):  
Self Assembly ◽  
Coiled Coil ◽  
Transcriptional Silencing ◽  
Higher Order ◽  
Significant Loss ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Krab Domain ◽  
Tripartite Motif ◽  
Self Association

AbstractTranscription of transposable elements is tightly regulated to prevent damage to the genome. The family of KRAB domain-containing zinc finger proteins (KRAB-ZFPs) and KRAB-associated protein 1 (KAP1/TRIM28) play a key role in regulating retrotransposons. KRAB-ZFPs recognize specific retrotransposon sequences and recruit KAP1, which controls the assembly of an epigenetic silencing complex including histone H3K9 methyltransferase SETDB1. The chromatin remodeling activities of this complex repress transcription of the targeted transposable element and any adjacent genes. Here, we use biophysical and structural approaches to show that the tripartite motif (TRIM) of KAP1 forms antiparallel dimers, which further assemble into tetramers and higher-order oligomers in a concentration-dependent manner. Structure-based mutations in the B-box 1 domain prevented higher-order oligomerization without a significant loss of retrotransposon silencing activity in a cell-based assay, indicating that, in contrast to other TRIM family members, self-assembly is not essential for the function of KAP1. The crystal structure of the KAP1 RBCC dimer identifies the KRAB domain binding site, in the coiled-coil domain near the dyad. Mutations at this site abolished KRAB binding and transcriptional silencing activity of KAP1. This work identifies the interaction interfaces in the KAP1 RBCC motif responsible for self-association and KRAB binding and establishes their role in retrotransposon silencing.

scholarly journals Rheological and Nutritional Characterization of Sweet Corn By-Product (Cob) to Develop a Functional Ingredient Applied in Dressings

2021 ◽  
Vol 8 ◽  
Author(s):  
Sandra Castillo ◽  
Alexis Rodríguez ◽  
Minerva Bautista-Villarreal ◽  
Nallely García-Solano ◽  
Claudia Gallardo-Rivera ◽  
...  
Keyword(s):  
Particle Size ◽  
Sweet Corn ◽  
Flow Behavior ◽  
Dependent Manner ◽  
Corn Cob ◽  
Concentration Dependent Manner ◽  
Consistency Coefficient ◽  
Coalescence Rate ◽  
Oil In Water

In this study, a flour from corn cob (central core of the maize ear, stage R4) was obtained through three treatments. The three flours obtained were characterized by bromatological analysis, yield, and granulometry. Additional dressing-type oil in water (O/W) emulsions were developed, varying the formulation by incorporating distinct amounts of corn cob flour. The formulations' stability was evaluated over a period of 21 days, determining the particle size, creaming index, coalescence rate, consistency coefficient (k), and flow behavior indices (n). Results have shown significant differences in protein, fat, and carbohydrate content in the flour, depending on the cooking treatment. A good percentage of grinding yield was obtained (98%), in addition to several fractions by granulometry (60, 120, 250 MESH), showing differences in their nutritional content. Finally, the particle size of O/W emulsions developed varied among formulations. The combination of 0.6% of xanthan gum (XG) and corn cob flour showed major stability in average droplet size. No significant differences were observed in the coalescence rate values for the three formulations. Still, significant differences in the creaming index were evidenced in those formulations without XG or corn cob flour. The results regarding the consistency coefficient (k) and flow behavior indices (n) suggest a possible synergy between XG and flour of corn cob for enhancing the viscosity and pseudoplasticity of dressings in a concentration-dependent manner.

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