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排序方式: 共有175条查询结果,搜索用时 15 毫秒
1.
2.
Carbon nanotube array-based biosensor 总被引:8,自引:0,他引:8
Aligned multi-wall carbon nanotubes (MWNT) grown on platinum substrate are used for the development of an amperometric biosensor. The opening and functionalization by oxidation of the nanotube array allows for the efficient immobilization of the model enzyme, glucose oxidase. The carboxylated open-ends of nanotubes are used for the immobilization of the enzymes, while the platinum substrate provides the direct transduction platform for signal monitoring. It is also shown that carbon nanotubes can play a dual role, both as immobilization matrices and as mediators, allowing for the development of a third generation of biosensor systems, with good overall analytical characteristics. 相似文献
3.
Patrina Paraskevopoulou Eleftheria Petalidou Nikos Psaroudakis Pericles Stavropoulos Konstantinos Mertis 《Monatshefte für Chemie / Chemical Monthly》2005,136(12):2035-2039
Summary. Primary phenylmethanols are selectively and efficiently oxidized to the corresponding aldehydes by the system C6H5IO/(C6H5)4PBr/CH2Cl2, T = 298 K under aerobic conditions. The use of the relatively stable iodosobenzene, an iodine(III) compound, in place of the
usually employed and potentially explosive iodine(V) reagents, the easy work-up procedure, and the facile recycling of solvent
and oxidant provides a convenient and environmentally benign oxidation method. 相似文献
4.
A total internal reflection (TIR)-based biochip utilizing a polymer-filled cavity with a micromirror sidewall has been designed and fabricated. The implementation of the micromirror sidewall cavity facilitates precise alignment of the excitation light beam into the system. The incident angle of illumination can be easily modified by selecting polymers of different indices of refraction while optical losses are minimized. The design enables the hybrid, vertical integration of a laser diode and a CCD camera, resulting in a compact optical system. Brownian motion of fluorescent microspheres and real-time photobleaching of rhodamine 6G molecules is demonstrated. The proposed TIR-based chip simplifies current TIR optical configurations and could potentially be used as an optical-microfluidic platform for an integrated lab-on-a-chip microsystem. 相似文献
5.
The irradiation of the 3-phenyl-2H-azirines 1a–c in the presence of diethyl benzoylphosphonate ( 8 ) in cyclonexane solution, using a mercury high pressure lamp (pyrex filter), yields the diethyl (4, 5-diphenyl-3-oxazolin-5-yl)-phosphonates 9a–c (Scheme 3). In the case of 1b a mixture of two diastereomeric 3-oxazolines, resulting from a regiospecific but non-stereospecific cycloaddition of the benzonitrile-benzylide dipole 2b to the carbonyl group of the phosphonate 8 , was isolated. Benzonitrile-isopropylide ( 2a ), generated from 2,2-dimethyl-3-phenyl-2H-azirine ( 1a ), undergoes a cycloaddition reaction to the ester-carbonyl group of diethyl ethoxycarbonylphosphonate ( 15 ) with the same regiospecificity to give the 3-oxazoline derivative 16 (Scheme 5). The azirines 1a–c , on irradiation in benzene in the presence of diethyl vinylphosphonate ( 17 ) give non-regiospecifically the Δ1-pyrrolines 13a–c and 14a–c (Scheme 6). 相似文献
6.
Enzyme stabilization strategies based on electrolytes and polyelectrolytes for biosensor applications 总被引:3,自引:0,他引:3
Chaniotakis NA 《Analytical and bioanalytical chemistry》2004,378(1):89-95
The achievements in the area of enzyme stabilization based on electrolytes, polyelectrolytes and polyols is reviewed, in the context of biosensor applications. Both the storage and operational stabilities of the biosensors can be improved using these stabilizers. The deactivation of the enzymes used for the development of biosensors from thermal shock, proteolytic degradation, and non-specific metal-catalyzed oxidation can be drastically reduced with the use of one or more of these stabilizers. It is attempted to deconvolute the effect of these additives on (a) the storage stability or shelf life, and (b) the operational stabilities of the biosensors. Even though there are a large number of techniques and reports dealing with enzyme stabilization, their application to biosensor technology is still very limited. It is thus concluded that the use of the existing enzyme stabilization techniques will have a drastic effect on the storage and operational stabilities of biosensors in the near future. 相似文献
7.
Georgia‐Paraskevi Nikoleli Muhammad Q. Israr Nikolaos Tzamtzis Dimitrios P. Nikolelis Magnus Willander Nikolas Psaroudakis 《Electroanalysis》2012,24(6):1285-1295
The present article describes a miniaturized potentiometric urea lipid film based biosensor on graphene nanosheets. Structural characterization of graphene nanosheets for miniaturization of potentiometric urea lipid film based biosensors have been studied through atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. UV‐Vis and Fourrier transform IR (FTIR) spectroscopy have been utilized to study the pre‐ and postconjugated surfaces of graphene nanosheets. The presented potentiometric urea biosensor exhibits good reproducibility, reusability, selectivity, rapid response times (~4 s), long shelf life and high sensitivity of ca. 70 mV/decade over the urea logarithmic concentration range from 1×10?6 M to 1×10?3 M. 相似文献
8.
Tao Xu Nikolas A. Savage Guangbin Dong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(7):1922-1926
The rhodium‐catalyzed formation of all‐carbon spirocenters involves a decarbonylative coupling of trisubstituted cyclic olefins and benzocyclobutenones through C C activation. The metal–ligand combination [{Rh(CO)2Cl}2]/P(C6F5)3 catalyzed this transformation most efficiently. A range of diverse spirocycles were synthesized in good to excellent yields and many sensitive functional groups were tolerated. A mechanistic study supports a hydrogen‐transfer process that occurs through a β‐H elimination/decarbonylation pathway. 相似文献
9.
10.
Anastasia Liakakou Apostolis Angelis Dimitrios P. Papachristos Nikolas Fokialakis Antonios Michaelakis Leandros A. Skaltsounis 《Molecules (Basel, Switzerland)》2021,26(11)
The present work describes the use of Centrifugal Partition Chromatography (CPC) for the bio-guided isolation of repellent active volatile compounds from essential oils. Five essential oils (EOs) obtained from three Pinus and two Juniperus species were initially analyzed by gas chromatography–mass spectrometry (GC/MS) and evaluated for their repellent properties against Aedes albopictus. The essential oil from needles of P. pinea (PPI) presented the higher activity, showing 82.4% repellency at a dose of 0.2 μL/cm2. The above EO, together with the EO from the fruits of J. oxycedrus subsp. deltoides (JOX), were further analyzed by CPC using the biphasic system n-Heptane/ACN/BuOH in ratio 1.6/1.6/0.2 (v/v/v). The analysis of PPI essential oil resulted in the recovery of (−)-limonene, guaiol and simple mixtures of (−)-limonene/β-pheladrene, while the fractionation of JOX EO led to the recovery of β-myrcene, germacrene-D, and mixtures of α-pinene/β-pinene (ratio 70/30) and α-pinene/germacrene D (ratio 65/45). All isolated compounds and recovered mixtures were tested for their repellent activity. From them, (−)-limonene, guaiol, germacrene-D as well the mixtures of (−)-limonene/β-pheladrene presented significant repellent activity (>97% repellency) against Ae. albopictus. The present methodology could be a valuable tool in the effort to develop potent mosquito repellents which are environmentally friendly. 相似文献