Papers by Keyword: Cysteine

Abstract: Several kinds of spherical cysteine grafted cobalt/manganese imprinted crosslinking chitosan spheres were synthesized for Mn²⁺ and Co²⁺ removal, in which Mn²⁺ and Co²⁺ were used separately or together as imprinting ions. Structures of the adsorbents were analyzed utilizing the techniques of SEM and FTIR. The effects of initial pH, contact time, presence of other cations, initial Mn²⁺ and Co²⁺ concentration on adsorption were investigated. Furthermore, adsorption kinetics and isotherm were studied, which showed sorption data fitted to pseudo-second-order and Langmuir models for both Mn²⁺ and Co²⁺. The overall results indicated the possibility of using Cys–Co/Mn–CCTS–2 for efficient removal of Mn²⁺ and Co²⁺ from dilute low-level radioactive liquid waste.

Abstract: This research was to study the efficiency of cysteine (Cys) acted as a natural antioxidant, which was encapsulated in alginate/chitosan (AG/CS) microcapsules to control the thermal oxidative degradation of natural rubber STR 5L. The microcapsules were prepared by a combined method based on ionic gelation and electrospraying techniques. The preparation of AG/CS microcapsules were executed to find the appropriate parameters such as applying voltage and concentration of alginate and chitosan. The applied voltage achieved for controlling the particle size as well as narrow size distribution of microcapsule. The AG/CS/Cys microcapsules were found to be a spherical shape and the average size was approximately 120 μm. The percentage of cysteine encapsulated within AG/CS microcapsules was increased with the increasing of chitosan concentration and encapsulation efficiency of cysteine in the microcapsules is about 81%. Core-shell structure of the microcapsule was confirmed by confocal laser scanning microscopy. After that, the natural rubber STR 5L mixed with AG/CS/Cys microcapsules was evaluated the oxidative resistance by Wallace plasticity. Thermal aging test according to standard ASTM D1349 at 70°C of the STR 5L mixed with AG/CS/Cys microcapsules were carried out. Weight-average molecular weight (w) of the rubber sample before and after aging test was also investigated by gel permeation chromatography. The w of rubber sample before and after aging test presented clearly results depending on the aging time. Concisely, the AG/CS/Cys microcapsules have a potential to control release Cys and can be used to control the deterioration of raw STR 5L. The model of this encapsulation is expected to be applied with other applications.

Abstract: This study deals with cysteine on gold (Au) nanoparticles which prepared by sodium citrate reduction. The effects of cysteine conjugated Au nanoparticles (Cys-c-Au NPs) on the microstructure and properties of the were investigated by Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and free radical scavenging ability. The results of UV-Vis and FTIR show that the cysteine was conjugated on Au NPs surface and the conjugates were found to be stable in water. The Energy-dispersive spectrometer (EDS) result shows the typical pick of the element sulfur (S) on surface of Cys-c-Au NPs. Finally, conjugates exhibited free radical scavenging ability in presence of cysteine.

Abstract: Ninhydrin chromogenic reactions are widely used to analyze and characterize amino acids, peptides, and proteins. In this study, the spectroscopy behavior of ninhydrin reaction with mercapto amino acid and polypeptide has been investigated. The maximum absorption wavelength of glutathione reaction with ninhydrin was 568 nm; the maximum absorption wavelength of cysteine reaction with ninhydrin was 457 nm. Under the optimized wavelength condition, glutathione and cysteine in the certain concentration range exhibt good linear relationship and low detection limit.

Abstract: Two novel fluorescent chemodosimeters will be presented for the selective detection of cysteine over homocysteine and glutathione in aqueous solvent. First, a rhodamine-based fluorescent probe (1) will be reported. Masked with a para-hydroxybenzyl alcohol (HBA) unit, probe 1 initially showed a weak fluorescence but displayed a strong fluorescence through a series of reactions of Michael addition and intramolecular cyclization of cysteine, followed by deprotection of HBA. The caged probe (1) exhibited a selective and sensitive response toward cysteine over homocysteine and glutathione in HEPES buffer. Secondly, a fluorescein-based fluorescent probe will be discussed. A bromoacetyl functionalized fluorescein chemodosimeter (2) was utilized as a fluorescent probe for cysteine. The probe showed a selective and sensitive response to cysteine over homocysteine and glutathione in aqueous buffer through a rapid cyclization reaction. When cysteine was added, a fast fluorescence turn-on change of 2 was observed and applied to the in-vivo imaging of cysteine.

Abstract: While bio(organic-inorganic) compatibility and absence of cytotoxicity are crucial to create a successful nanocarrier for applications in biosensing and drug delivery, the study of its stability before commercialization is quite important. In the present work, the stability of gold nanoparticles (AuNPs) functionalized with L-Cysteine (Cys) and Cysteine-Glycine (Cys-Gly) was studied. The AuNPs surface modification with Cys and CysGly was performed to improve their biocompatibility and, after that, the stability of capped AuNPs was investigated. The synthetized AuNPs using 10 mM of cysteine and 20 mM of Cys demonstrated stability after 1 month of storage, while all other concentration ratios resulted in the formation of chain-like conglomerates. For AuNP capped with CysGly all modifier concentrations led to stable samples within 1 month of storage.

Abstract: As the population ages, dementia disease is increasingly becoming the most concerned social problems. According to the cause of dementia, it can be divided into many kinds class, among them with Alzheimer's Disease (Alzheimers diseases, AD) and Vascular Dementia (Vascular Dementia, VD) are common. Data shows it accounts for nearly 60% of total AD dementia patients, VD (20%), but only 2% of patients could get timely diagnosis and treatment, make its cognitive damage to a certain extent suppress and improve. for untimely diagnosis and treatment, most patients makes the disease development worse. In recent years, studies have shown that plasma Homocysteine,Hcy levels associated with AD. And studies show that from the power of the risk factors to the mechanism analysis, dementia disease level correlation with magnesium ions. On this basis, this study of plasma homocysteine in patients with AD,VD and magnesium ion detection results were analyzed retrospectively. Discuss their levels between the distributio relationship of patients ages in AD and VD.

Abstract: Au nanoparticles (NPs) functionalized with L-cysteine (Cys) and cysteine-glycine (Cys-Gly) were synthetized. The AuNPs were prepared using sodium citrate as reducing agent. The influence of the molar concentrations of Cys and Cys-Gly, as well as the sodium citrate is studied on particle size and particle size distribution. TEM measurements revealed the formation of AuNPs with diameter in the range 5-35 nm which corresponds to nontoxic sizes [we should add a reference here, perhaps number one]. The optimal particle size for biomedical application along with narrow particle size distribution was observed for samples prepared with molar ratio of CAu:Ccitrate = 1:10. The results of UV-Vis spectroscopy revealed the interaction of the AuNPs with Cys and Gly-Cys demonstrated by a visible change in the absorption intensities of the plasmon peak located at 520 nm after AuNP functionalization and a slight shifting of this gold nanoparticles plasmon peak. Thus, any dielectric shell on surface of particles with more refraction index (and, correspondingly, dielectric function) can produce the particles with the red shift. Such effect of the surface shell with red-shift in the range of few nanometers observed for the AuNPs functionalized with Cys and Cys-Gly (Fig. 4) can be interpreted as thin or discontinuous layer of aminoacid molecules according to the data of optical spectra simulation.

Abstract: Using PEG-10000 and sodium citrate as stabilizer, and NaBH₄ as reducer, a stable nanosilver (AgNPs) sol was prepared. In pH 6.6 phosphate buffer solution containing NaCl, the AgNPs were aggregated to large particles, which lead to resonance Rayleigh scattering (RRS) peak at 350 nm enhancement. Upon addition of cysteine, the peak decreased. The decreased value ΔI is linear to cysteine concentration in the range of 5.0×10^-8-6.0×10^-7 mol/L. Thus, a new RRS method was proposed for detection of cysteine.

Abstract: Biomolecule functionalized gold nanoparticles offer a broad range of applications in biomedical and bioanalytical areas. In this work, we investigated the spectroscopy behavior of gold nanoparticles modified with mercapto amino acid, cysteine. We found that the interaction of gold nanoparticles with cysteine resulted in a shift in the plasmon bands to higher wavelengths at the lower concentration of cysteine and in acidity solution.