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Taishan, China

Xia C.-C.,Taishan Medicine College
Acta Crystallographica Section E: Structure Reports Online | Year: 2010

In the title compound, C 11H 13NO 4, the two fused rings are almost coplanar, making a dihedral angle of 3.02 (8)°. In the crystal, chains are formed parallel to [010] through N - H⋯O hydrogen bonds between the amine and carbonyl groups. Source

Huang X.,Shantou University | Li Y.,Taishan Medicine College | Zhang X.,Shantou University | Chen Y.,Shantou University | Gao W.,Shantou University
Analyst | Year: 2015

An efficient aptasensor was developed in which graphene oxide (GO) was employed as an indicator for both electrochemical impedance spectroscopy and electrochemiluminescence (ECL) signal generation. The aptasensor was fabricated by self-assembling the ECL probe of a thiolated adenosine triphosphate binding aptamer (ABA) tagged with a Ru complex (Ru(bpy)32+ derivatives) onto the surface of gold nanoparticle (AuNP) modified glassy carbon electrode (GCE). ABA immobilized onto AuNP modified GCE could strongly adsorb GO due to the strong π-π interaction between ABA and graphene oxide; ECL quenching of the Ru complex then takes place because of energy transfer and electron transfer, and a large increase of the electron transfer resistance (Ret) of the electrode. While in the presence of target adenosine triphosphate (ATP), the ABA prefers to form ABA-ATP bioaffinity complexes, which have weak affinity to graphene oxide and keep the graphene oxide away from the electrode surface, thus allowing the ECL signal enhancement, and in conjunction with the decrease of the Ret. Because of the high ECL quenching efficiency, unique structure, and electronic properties of graphene oxide, the Ret and ECL intensity versus the logarithm of ATP concentration was linear in the wide range from 10 pM to 10 nM with an ultra-low detection limit of 6.7 pM to 4.8 pM, respectively. The proposed aptasensor exhibited excellent reproducibility, stability, and outstanding selectivity, and ATP could be effectively distinguished from its analogues. More significantly, this efficient ECL aptasensor strategy based on GO acting both as an electrochemical and ECL signal indicator is general and can be easily extended to other biological binding events. This journal is © The Royal Society of Chemistry. Source

Huang X.,Shantou University | Li Y.,Taishan Medicine College | Xie X.,Shantou University | Xu Y.,Shantou University | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2016

A novel and environmentally friendly reverse fluorescent immunoassay approach was proposed and utilized for sensing human chorionic gonadotropin (HCG) in human serum by coupling a newly prepared and highly fluorescent glutathione-stabilized silver-gold nano-alloy (GSH-AgAuNAs) with magnetic nanoparticles (MNPs). To construct such a reverse system, fluorescent GSH-AgAuNAs and MNPs were first prepared and bio-functionalized with monoclonal antibodies (Mab-I and Mab-II) toward HCG antigen, respectively. Then, the GSH-AgAuNAs functionalized with Mab-I were incubated with HCG, followed by the addition of MNPs attached to Mab-II. Thereafter, a sandwich-type immunoassay could be constructed for determination of HCG owing to the antibody-antigen recognition between the functionalized GSH-AgAuNAs and MNPs. Afterwards, a magnetic collection was employed. Hence, the amount of GSH-AgAuNAs would be reduced through an immuno-magnetic separation, thus weakening the fluorescent intensity. Different from conventional immunoassay, our work determined the quantitative signal by measuring the decreasing gradient fluorescent intensity. Under optimal conditions, the developed reverse method exhibited a wide linear range of 0.5-600 ng mL-1 toward HCG with a detection limit of 0.25 ng mL-1. Additionally, the proposed immunoassay was validated using spiked samples, illustrating a satisfactory result in practical application. © 2015 Springer-Verlag Berlin Heidelberg. Source

Huang X.,Shantou University | Lin Y.,Shantou University | Chen J.,Shantou University | Chen Y.,Shantou University | And 2 more authors.
New Journal of Chemistry | Year: 2015

A new and environmentally friendly approach for the preparation of glutathione-stabilized silver-gold nano-alloys (GSH-AgAuNAs) with high fluorescence was proposed in this work. The as-prepared GSH-AgAuNAs were characterized with various methods and coupled with copper ions (Cu2+) to form a fluorescent switch probe (GSH-AgAuNAs/Cu2+ combination) for the detection of l-histidine. The fluorescence of the GSH-AgAuNAs was first quenched by adding an appropriate amount of Cu2+ solution. Then, in the presence of l-histidine, the GSH-AgAuNAs/Cu2+ combination solution exhibited an obvious fluorescence enhancement due to the specific interaction between the imidazole group of l-histidine and Cu2+. The strong chelation between l-histidine and Cu2+ illustrated the feasibility of constructing a selective "switch on" probe for the detection of l-histidine over other amino acids. Different from other methods for detecting l-histidine based on fluorescent nanomaterials, our work promises high selectivity, simplicity and the avoidance of organic solvents. Under the optimal conditions, the newly constructed GSH-AgAuNAs/Cu2+ fluorescent probe showed a satisfactory linear detection range of 2 to 40 μM, with a detection limit of 1.19 μM. The practical use of the GSH-AgAuNAs/Cu2+ combination in real human serum samples was tested, illustrating its potential application in l-histidine detection. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. Source

Huang X.,Shantou University | Li Y.,Taishan Medicine College | Chen Y.,Shantou University | Gao W.,Shantou University
RSC Advances | Year: 2015

An ingenious sensing strategy for detecting thrombin in human serum has been developed on the basis of a hairpin DNA sequence and resonance light scattering (RLS) technique. A thrombin aptamer sequence was embedded inside the hairpin DNA strand (H-eTBA), which was designed to be the loop-stem structure. Moreover, methylene blue (MB) was utilized as the RLS signal indicator according to its different affinity to single or double stranded DNA. Upon the addition of thrombin, the thrombin aptamer inside H-eTBA interacted specifically with thrombin. Thus the conformation of H-eTBA would change. After the introduction of the DNA strand (CTBA), which was complementary to H-eTBA, the amount of double stranded DNA would decrease as a consequence. Later when MB solution was added, the RLS signal would present various response values based on different amounts of thrombin. The determination of thrombin in human serum could be obtained with a detection limit of 0.32 nM and this specific sensor could be applied to detect thrombin practically. Furthermore, this aptasensor showed quite good selectivity and simplicity toward thrombin. Finally, the proposed sensing method showed its superiority with selectivity and practicability, which could be used as a simple platform for thrombin detection. © 2015 The Royal Society of Chemistry. Source

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