Polysulfide/Graphene Nanocomposite Film for Simultaneous Electrochemical Determination of Cadmium and Lead Ions

Ruyuan Jiang,Niantao Liu,Yuhong Su,Sanshuang Gao,Xamxikamar Mamat,Thomas Wågberg,Yongtao Li,Xun Hu,Guangzhi Hu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.08

An integrative electroanalytical method was developed for detecting Cd2+ and Pb2+ ions in aqueous solutions. Polysulfide/graphene (RGO-S) nanocomposites were prepared and their performance as electrochemical sensors for Cd2+ and Pb2+ was evaluated. The RGO-S nanocomposite was carefully characterized by scanning electron microscopy with energy-dispersive X-ray spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy. The as-prepared RGO-S was incorporated into a pyrolytic graphite electrode (RGO-S/PGE) and used for detecting trace amount of Cd2+ and Pb2+ by differential pulse anodic stripping voltammetry. Under optimal conditions, the stripping peak current of RGO-S/PGE varies linearly with heavy metal ion concentration in the ranges 2.0–300 μg L -1 for Cd2+ and 1.0–300 μg L -1 for Pb2+. The limits of detection for Cd2+ and Pb2+ were estimated to be about 0.67 μg L -1 and 0.17 μg L -1, respectively. The prepared electrochemical heavy-metal-detecting electrode provides good repeatability and reproducibility with high sensitivity, making it a suitable candidate for monitoring Cd2+ and Pb2+ concentrations in aqueous environmental samples.

Ultrasound guided breast cancer surgery & VABB experiences in China

Chenguang Zhang,Yongtao Li,Xiowen Wang,Weihua Jiang,Lina Yi,Jianghua Ou 대한외과학회 2016 대한외과학회 학술대회 초록집 Vol.2016 No.11

Induction of Phase I, II and III Drug Metabolism/Transport by Xenobiotics

Xu Chang Jiang,Li Christina YongTao,Kong AhNg Tony The Pharmaceutical Society of Korea 2005 Archives of Pharmacal Research Vol.28 No.3

Drug metabolizing enzymes (DMEs) play central roles in the metabolism, elimination and detoxification of xenobiotics and drugs introduced into the human body. Most of the tissues and organs in our body are well equipped with diverse and various DMEs including phase I, phase II metabolizing enzymes and phase III transporters, which are present in abundance either at the basal unstimulated level, and/or are inducible at elevated level after exposure to xenobiotics. Recently, many important advances have been made in the mechanisms that regulate the expression of these drug metabolism genes. Various nuclear receptors including the aryl hydrocarbon receptor (AhR), orphan nuclear receptors, and nuclear factor-erythoroid 2 p45-related factor 2 (Nrf2) have been shown to be the key mediators of drug-induced changes in phase I, phase II metabolizing enzymes as well as phase III transporters involved in efflux mechanisms. For instance, the expression of CYP1 genes can be induced by AhR, which dimerizes with the AhR nuclear translocator (Arnt) , in response to many polycyclic aromatic hydrocarbon (PAHs). Similarly, the steroid family of orphan nuclear receptors, the constitutive androstane receptor (CAR) and pregnane X receptor (PXR), both heterodimerize with the ret-inoid X receptor (RXR), are shown to transcriptionally activate the promoters of CYP2B and CYP3A gene expression by xenobiotics such as phenobarbital-like compounds (CAR) and dexamethasone and rifampin-type of agents (PXR). The peroxisome proliferator activated receptor (PPAR), which is one of the first characterized members of the nuclear hormone receptor, also dimerizes with RXR and has been shown to be activated by lipid lowering agent fib rate-type of compounds leading to transcriptional activation of the promoters on CYP4A gene. CYP7A was recognized as the first target gene of the liver X receptor (LXR), in which the elimination of cholesterol depends on CYP7A. Farnesoid X receptor (FXR) was identified as a bile acid receptor, and its activation results in the inhibition of hepatic acid biosynthesis and increased transport of bile acids from intestinal lumen to the liver, and CYP7A is one of its target genes. The transcriptional activation by these receptors upon binding to the promoters located at the 5-flanking region of these GYP genes generally leads to the induction of their mRNA gene expression. The physiological and the pharmacological implications of common partner of RXR for CAR, PXR, PPAR, LXR and FXR receptors largely remain unknown and are under intense investigations. For the phase II DMEs, phase II gene inducers such as the phenolic compounds butylated hydroxyanisol (BHA), tert-butylhydroquinone (tBHQ), green tea polyphenol (GTP), (-)-epigallocatechin-3-gallate (EGCG) and the isothiocyanates (PEITC, sul­foraphane) generally appear to be electrophiles. They generally possess electrophilic-medi­ated stress response, resulting in the activation of bZIP transcription factors Nrf2 which dimerizes with Mafs and binds to the antioxidant/electrophile response element (ARE/EpRE) promoter, which is located in many phase II DMEs as well as many cellular defensive enzymes such as heme oxygenase-1 (HO-1), with the subsequent induction of the expression of these genes. Phase III transporters, for example, P-glycoprotein (P-gp), multidrug resistance-associated proteins (MRPs), and organic anion transporting polypeptide 2 (OATP2) are expressed in many tissues such as the liver, intestine, kidney, and brain, and play crucial roles in drug absorption, distribution, and excretion. The orphan nuclear receptors PXR and GAR have been shown to be involved in the regulation of these transporters. Along with phase I and phase II enzyme induction, pretreatment with several kinds of inducers has been shown to alter the expression of phase III transporters, and alter the excretion of xenobiotics, which implies that phase III transporters may also be similarly regulated in a coord

Antibiofilm activity of polyethylene glycol-quercetin nanoparticles-loaded gelatin-N,O-carboxymethyl chitosan composite nanogels against Staphylococcus epidermidis

Wanhe Luo,Yongtao Jiang,Jinhuan Liu,Beibei Sun,Xiuge Gao,Samah Attia Algharib,Dawei Guo,Jie Wei,Yurong Wei The Korean Society of Veterinary Science 2024 Journal of Veterinary Science Vol.25 No.2

Background: Biofilms, such as those from Staphylococcus epidermidis, are generally insensitive to traditional antimicrobial agents, making it difficult to inhibit their formation. Although quercetin has excellent antibiofilm effects, its clinical applications are limited by the lack of sustained and targeted release at the site of S. epidermidis infection. Objectives: Polyethylene glycol-quercetin nanoparticles (PQ-NPs)-loaded gelatin-N,O-carboxymethyl chitosan (N,O-CMCS) composite nanogels were prepared and assessed for the on-demand release potential for reducing S. epidermidis biofilm formation. Methods: The formation mechanism, physicochemical characterization, and antibiofilm activity of PQ-nanogels against S. epidermidis were studied. Results: Physicochemical characterization confirmed that PQ-nanogels had been prepared by the electrostatic interactions between gelatin and N,O-CMCS with sodium tripolyphosphate. The PQ-nanogels exhibited obvious pH and gelatinase-responsive to achieve on-demand release in the micro-environment (pH 5.5 and gelatinase) of S. epidermidis. In addition, PQ-nanogels had excellent antibiofilm activity, and the potential antibiofilm mechanism may enhance its antibiofilm activity by reducing its relative biofilm formation, surface hydrophobicity, exopolysaccharides production, and eDNA production. Conclusions: This study will guide the development of the dual responsiveness (pH and gelatinase) of nanogels to achieve on-demand release for reducing S. epidermidis biofilm formation.

Prediction Method for Fine Particle Loss Rate of Sandy Soil under Suffusion

Yiteng Zhang,Mingnian Wang,Li Yu,Yongtao Jiang,Borong Li 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.6

In the process of seepage, the internally unstable fine particles of sandy soil are easy to be lost and form suffusion, which has a negative effect on the geotechnical building or foundation. The loss rate of fine particles is a key parameter for soil mechanical property degradation and stability analysis. In order to predict the loss rate of fine particles in sandy soil under suffusion, the internal stability evaluation criteria for determining whether soil will undergo suffusion is discussed first. Second this paper gives critical hydraulic gradient for erosion initiation and introduces the stress reduction factor. And then considering the difference of soil particles' forces, the stress reduction factor is modified, meanwhile the “erosion initiation probability of fine particles” is introduced to quantify the erosion initiation of fine particles. Next the migration process of fine particles in the pore network of soil is analyzed, and the probability of fine particles through constriction and the migration distance are given. Finally, the law of fine particle erosion and deposition are given according to the law of fine particle erosion initiation and migration, and the prediction method of fine particle loss rate was formed based on the law of mass conservation. The calculated results of fine particle loss by this prediction method are in good agreement with the numerical results, and the error is basically within 15%.