1,893 research outputs found
Electrochemical characteristics of a carbon-based thick-film L-lactate biosensor using L-lactate dehydrogenase
No full textCarbon-based thick-film electrodes employing nicotinamide adenine dinucleotide (NAD(+))-dependent dehydrogenases were constructed by screen printing. Cyclic voltammetric and amperometric investigations of the thick-film electrode showed significantly different electrocatalytic properties toward NADH compared to conventional polished electrodes. Electrochemical oxidation of NADH was attained at the low potential of +350 mV vs. Ag/AgCl at the thick-him carbon electrode, and this can be attributed to increased electrocatalytic sites due to the rough and jagged electrode surface and the formation of a microelectrode array-like structure at the electrode surface. Based on these observations, a thick-him lactate biosensor using lactate dehydrogenase was developed. Analytical performance of the resulting lactate biosensor was evaluated in terms of sensitivity and stability
Prevalence investigation of swine pathogens in the wild rodents and cats
No full textKim, Y.H.; Seo, T.W.; Yi, J.Y.; Hahn, T.W.; Kim, H.C.; Han, J.H.; Yoon, B.I.. (2008). Prevalence investigation of swine pathogens in the wild rodents and cats. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/155086
Functionalization of a poly(amidoamine) dendrimer with ferrocenyls and its application to the construction of a reagentless enzyme electrode
No full textPoly(amidoamine) dendrimers having various degrees of modification with the redox-active ferrocenyls were prepared by controlling the molar ratio of ferrocenecarboxaldehyde to amine groups of dendrimers, By alternate layer-by layer depositions of partial ferrocenyl-tethered dendrimers (Fc-D) with periodate-oxidized glucose oxidase (GOx) on a Au surface, an electrochemically and enzymatically active multilayered assembly of enzyme was constructed. The resulting GOx/Fc-D multilayer-associated electrodes were electrochemically analyzed, and the surface concentration of ferrocenyl groups, active enzyme coverage, and sensitivity were estimated. A 32% dendrimer modification level of surface amines to ferrocenyls was found to be an optimum in terms of enzyme-dendrimer network formation, electrochemical interconnectivity of ferrocenyls, and electrode sensitivity. With the prepared Fc(32%)-tethered dendrimers, mono- and multilayered GOx/Fc-D electrodes were constructed, and their electrochemical and catalytic properties were characterized. The bioelectrocatalytic signals from the multilayered GOx/Fc-D electrodes were shown to be directly correlated to the number of deposited bilayers. From this result, it seems that the electrode sensitivity is directly controllable, and the multilayer-forming strategy with partial ferrocenyl-tethered dendrimers is useful for the construction of reagentless biosensors
Reversible association/dissociation reaction of avidin on the dendrimer monolayer functionalized with a biotin analogue for a regenerable affinity-sensing surface
No full textAnew approach to a repeatedly regenerable affinity-sensing surface was developed based on the reversible association/dissociation reactions between avidin and biotin analogues. For the affinity surface, a fourth generation poly(amidoamine) dendrimer monolayer was first constructed on the 11-mercaptoundecanoic acid self-assembled monolayer on gold. The dendritic surface amine groups then were functionalized with biotin analogues, desthiobiotin (1), or newly synthesized desthiobiotin amidocaproate (2), an extended form of 1, which shows lower affinity toward avidin. To test the association/dissociation reaction cycles at the affinity surface, avidin adlayer was formed onto the biotin analogue functionalized surface and displaced with free biotin. To trace the stepwise reactions, biotinylated glucose oxidase (b-GOx) as a model enzyme was loaded onto the affinity surface, and cyclic voltammetric measurements were performed by registering the activity of the associated b-GOx. The efficient association/dissociation reaction cycles were registered, especially for the a-modified electrodes, implying steric hindrance from the ligand length for biospecific interaction. With the optimized affinity-surface construction steps and reaction conditions, continuous association/dissociation reaction cycles were achieved, resulting in a regenerable affinity surface
Protein-ligand interactions at poly(amidoamine) dendrimer monolayers on gold
No full textAvidin-biotin interactions as a typical protein-ligand model were investigated on the monolayers of a fourth-generation poly(amidoamine) dendrimer that were constructed on the self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid (MUA) on gold. Surface plasmon resonance (SPR) spectroscopic analysis revealed a resonance angle shift of 0.34degrees +/- 0.03degrees for the formation of dendrimer monolayers on reactive SAMs, which indicates that about 89% of the gold surface is covered with dendrimer molecules. The dendrimer monolayers were functionalized with biotin, and the efficacy of dendrimer monolayers as a biomolecular interface was evaluated in terms of the surface density of biotin ligands and the avidin binding level. For comparisons, the mixed SAMs and polymeric layers of poly-I.-lysine (PLL) on MUA SAMs were prepared and examined by a similar procedure. The specific binding of avidin to the biotinylated dendrimer monolayers, approached a surface density of 5.0 +/- 0.2 ng(.)mm(-2), which corresponds to about 88% surface coverage by avidin, showing a much higher level than those from mixed SAMs (2.3 +/- 0.1 ng(.)mm(-2)) and PLL layers (3.2 +/- 0.2 ng(.)mm(-2)). Interestingly, the fully biotinylated dendrimer monolayers gave rise to efficient avidin-biotin interactions, resulting in about 80% of the maximum avidin binding level, even under the condition that a serious steric hindrance would occur due to densely packed biotin ligands. These results strongly imply that efficient avidin-biotin interaction originates from a structural feature of dendrimer monolayers such as a surface exposure of derivatized biotin ligands and a corrugated surface
POLA KALIMAT PADA KUMPULAN DONGENG GADIS KOREK API KARYA H.C. ANDERSEN (SUATU KAJIAN SINTAKSIS)
No full textThis study described syntactic structure on fairy-tale collection of Gadis Korek Api by H.C. Andersen. The study which seen from syntactic structure is sentence pattern based on function category, category, and syntactic role. This study aimed to describe syntactic structure on fairy-tale collection of Gadis Korek Api by H.C. Andersen and it’s distribution towardh Indonesian language. This research used qualitative method and note method was employed for collecting the data. In analysing the data, the researcher used Agih method by applying Immediate Constituent Analysis technique (ICA) as a basic technique. A book entitled Gadis Korek Api and others fairy-tale are the work of danish author, H.C. Andersen that used Indonesian standard. The analysis showed syntactic structure of fairy-tale language which form of sentence pattern based on the user, the pattern of imperative sentence, sentence pattern contains conjunction, and sentence pattern of complex sentences. Keywords: Sentence Pattern; Fairy-tale; Syntactic.</p
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