Chenxu Yu

Fluorescent Nanoparticles from Several Commercial Beverages: Their Properties and Potential Application for Bioimaging

The presence of nanoparticles in beverages has raised great concern in terms of potential impacts to consumer health. Herein, carbon dots in beverages kvass, pony malta, pilsner beer, Vivant Storm, and Profit were identified. They were shown to have a strong fluorescence under the excitation of ultraviolet light. The emission peaks shift to longer wavelengths accompanied by a remarkable fluorescence intensity decrease. The carbon dots are in the nanosized range and roughly spherical in appearance. Elemental analysis by X-ray photoelectron spectroscopy demonstrated the composition of Kvass carbon dots to be C 83.17%, O 13.83%, and N 3.00%. No cytotoxicity was found at concentrations up to 20 mg/mL for human tongue squamous carcinoma cells, and they can be directly applied in both carcinoma and onion epidermal cell imaging. This work represents the first report of the carbon dots present in beverages, providing valuable insights into these nanoparticles for future biological imaging.

Stimulation of lymphocyte proliferation by oyster glycogen sulfated at C-6 position

In this study, glycogen was extracted from oyster Ostrea talienwhanensis Crosse and used as a model to investigate the structure-activity correlation of polysaccharides. Purified oyster glycogen was characterized by methylation analysis, nuclear magnetic resonance (NMR) spectroscopy and infrared spectroscopy (IR). The oyster glycogen was subsequently sulfated by chlorosulfonic acid-pyridine method, and a C-6 substituted species (SOG) was identified to be the primary sulfated oyster glycogen species by (13)C NMR spectroscopy. The molecular weight and sulfate content of the SOG was determined to be 3.2×10(4) g/mol and 33.6%, respectively. Another sulfated oyster glycogen species (SOG1) with C-2 and C-3 substitution was also identified at a lesser amount in the final product. SOG exhibited a much stronger stimulation effect to splenic lymphocyte proliferation than SOG1 in vitro, indicating that the position of sulfate substitution is a major determining factor on the efficacy of sulfated glycogens to stimulate lymphocyte proliferation.

Effects of abalone (Haliotis discus hannai Ino) gonad polysaccharides on cholecystokinin release in STC-1 cells and its signaling mechanism

Abalone gonad polysaccharide (AGP) -31, -32 and -33 prepared in this study had the molecular weight (MW) of 37.8, 32.2 and 27.5kDa, respectively. They all contained mannose, rhamnose, glucuronic acid, glucose, galactose, xylose, arabinose, and fucose, with very similar monosaccharide profile. All the three polysaccharides could significantly increase the secretion of cholecystokinin (CCK) in STC-1 cells. Among them, AGP-32 showed the strongest effect. However, the low-MW fragments of AGP-32 showed significantly lower activity than AGP-32 itself. It was also found that the inhibitors on calcium-sensing receptor (CaSR), protein kinase A (PKA), Ca(2+)⁄calmodulin-dependent protein kinase (CaMK) II, p38- mitogen-activated protein kinases (MAPK), and an intracellular calcium chelator all inhibited AGP-induced CCK secretion. To conclude, Ca(2+)/calmodulin (CaM)/CaMK, cyclic adenosine monophosphate (cAMP)/PKA and MAPK pathways are all involved in AGP-induced CCK secretion.

Presence and Formation Mechanism of Foodborne Carbonaceous Nanostructures from Roasted Pike Eel (Muraenesox cinereus)

Foodborne nanostructures have gained more and more attention in recent years. In this paper, the presence and physicochemical properties of carbonaceous nanostructures (CNSs) from roasted pike eel ( Muraenesox cinereus) were reported. The monodispersed CNSs are strongly photoluminescent under the illustration of ultraviolet (UV) light, with a fluorescent quantum yield of 80.16%, and display excitation-dependent emission behavior. The formation of CNSs is believed to go through a process of morphology evolution, including polymerization, pyrolysis, nucleation, growth, emergence, and blossom. The optical properties of the CNSs were shown to be affected by the roasting temperature. Furthermore, cellular uptake of the CNSs was investigated, and it is shown that the CNSs were clearly absorbed into live cells and were mainly distributed within the cell cytoplasm and not in the cell nucleus. This work is among the very first reports on CNSs present in roasted fish, providing valuable insights into the formation mechanism of such nanostructures and showcasing the biodistribution of these food-originated CNSs in live cells.

Microstructural characteristics of turbot (Scophthalmus maximus) muscle: effect of salting and processing

ABSTRACT The effect of salt concentration on the processing and characteristics of turbot muscle was investigated in this study. The turbot muscle samples were salted with 1%, 5%, 10%, 15%, or 20% w/w salt at 4°C for 3 h. Low-field nuclear magnetic resonance was utilized to characterize water distribution and water holding capacity in the samples. Nuclear magnetic resonance transverse (T2) relaxation identified three water components (T21, T22, and T23) which all exhibited characteristics correlated with water holding capacity. Textural analysis indicated that hardness and elasticity increased with increasing salt concentration. Histological imaging showed that with the increase of salt concentration, the muscle fiber diameter and area increased first and then decreased. The porosity of salted samples was higher than that of fresh ones. It was shown that salting at lower salt concentrations would lead to partial degradation of the fibrin in the tissue samples and the swelling of proteins. In treated samples, 5% w/w salt was shown to produce the best results. This study provides theoretical basis for the development of salted turbot meat products.

Nutritional value and flavor of turbot (Scophthalmus maximus) muscle as affected by cooking methods

ABSTRACT In this study, the effects of five cooking methods on nutritional value and flavor of turbot muscle were evaluated. Chemical compositions of samples were determined using AOAC methods, and the fatty-acid composition was determined by gas chromatography–mass spectrometry (GC–MS). Flavors of samples cooked using different methods were characterized by electronic nose. Volatile compounds were determined using solid-phase microextraction (SPME) followed by gas GC–MS. All the samples were investigated before/after cooking. The results showed that the fatty acids found in abundance in the raw sample were C22:6n-3, C16:0, C18:1n-7, and C20:5n-3. All of the fatty acids were detected in steamed samples, while some of the fatty acids were degraded in other cooking methods. Electronic nose can be used to distinguish samples cooked differently. 20, 17, 34, 20, and 23 compounds were detected in samples cooked by frying, baking, microwave heating, boiling in vacuum-sealed bag (BIVSB) and steaming, respectively. Aldehydes, ketones, alcohols, acids, and hydrocarbons were the main volatile components detected. In summary, steaming preserves water, protein, lipids and fatty acids the best in cooked samples while generates desirable flavor, it is recommended as the choice of cooking for turbot.

Bio-distribution and interaction with dopamine of fluorescence nanodots from roasted chicken

The potential health risks of food-borne nanoparticles are of great concern to public health. In this work, the formation and physicochemical properties of a class of fluorescent nanodots (FNDs) in roasted chicken were investigated. It was found that as the roasting temperature increased from 200 to 300 °C the size of the FNDs decreased significantly, from 17.1 to 2.1 nm. The FNDs, which mainly contain carbon (65%), are strongly fluorescent under ultraviolet light, exhibiting an excitation-dependent emission behavior. The fluorescence quantum yields of the FNDs were determined at 200, 250, and 300 °C, and were found to be 6.71 ± 0.21, 12.85 ± 0.34 and 17.46 ± 0.42%, respectively. These FNDs not only could be taken up by live cells and dispersed within the cytoplasm, but also could pass the blood-brain barrier (BBB) and accumulated in the brains of mice after oral feeding. The results of the fluorescence and Fourier transform infrared (FTIR) spectroscopy analysis clearly indicated that the FNDs can interact with the neurotransmitter dopamine in vitro through the formation of fluorescent conjugates. The relative cell viability decreased by 33% corresponding to FND-300 at a concentration of 4 mg mL-1. These results confirmed the presence of the FNDs in roasted chicken and revealed their potential bioeffects on human health, which calls for more research and evaluation.