PubMed Health⌕ Search

PubMed · 11209465

Amperometric biosensors based on microflow injection system.

Abstract

Novel electrochemical cells based on a microflow system combined with amperometric enzyme electrodes were developed and served for quantitative determination of various compounds, such as organophosphates and lactose. The resulting biosensors are selective and efficient owing to immobilization of the sensing elements on the electrodes. The sensors are easy to operate, and the procedures are rapid, accurate, reproducible, and inexpensive, requiring neither special skills and training nor complicated instrumentation. The use of a microflow cell ensures the continuous flux of a new substrate, thus preventing the accumulation or adsorption of products to the electrode. Miniaturization of the sensor has two main advantages: (1) it is easy to carry and therefore can be used outdoors as well, and (2) it allows working with low volumes of compounds and reagents, which is highly important when dealing with hazardous compounds.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

I Eshkenazi, V Sacks, T Neufeld, J Rishpon. Amperometric biosensors based on microflow injection system.. https://doi.org/10.1385/abab%3A89%3A2-3%3A217

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

C fragment of tetanus toxin hybrid proteins evaluated for muscle-specific transsynaptic mapping of spinal motor circuitry in the newborn mouse.

We investigated whether the non-toxic C fragment of tetanus toxin (TTC) fused to either beta-galactosidase or green fluorescent protein could be utilized to transsynaptically trace muscle-specific spinal circuitry in the neonatal mouse after i.m. injection into a single hindlimb muscle. We found that even with careful low volume injection (0.2-1.0 microl) into a single muscle (medial gastrocnemius), the TTC hybrid proteins spread rapidly to many other hindlimb muscles and to trunk musculature such that retrograde labeling of motoneurons could not be constrained to a single motoneuron pool. Retrogradely labeled motoneurons in the lower lumbar segments harboring the medial gastrocnemius motoneuron pool were first observed two hours after the medial gastrocnemius injection. Within the next 10 h, additional lumbar and lower thoracic motoneurons became labeled, and punctate labeling in the neuropil surrounding the motoneurons appeared. Many of the TTC hybrid protein-labeled puncta in the neuropil co-localized synaptotagmin, indicating that they represent presynaptic axon terminals onto motoneurons. Although this is consistent with retrograde transsynaptic passage, we found no evidence that the TTC hybrid proteins were transported further along premotor axons to label interneuron somata. The i.m. TTC injection procedure described here therefore provides an important tool for the study of presynaptic terminals onto motoneurons. However, additional technical modifications will be required to utilize TTC tracers for transsynaptic mapping of muscle-specific spinal motor circuitry in the neonatal mouse. We provide here a set of criteria for assessing the i.m. delivery of TTC tracers as a basis for future improvements in this technique.

Acetylthiocholine↗

para- and ortho-Pyridinium aldoximes in reaction with acetylthiocholine.

In the oximolysis reaction para-aldoximes K027 and TMB-4 react faster with ATCh than ortho-aldoximes HI-6 and K033. The reaction rate constants at 25 degrees C were 22 M(-1) min(-1) for HI-6 and K033, 230 M(-1) min(-1) for TMB-4 and 306 M(-1) min(-1) for K027. Semi-empirical calculations showed that differences in rates do not origin from different electron density on the oxygen of the oxime group, but can be explained by the steric hindrance of the oxime group within the molecule. Thermodynamic parameters, DeltaG#, DeltaH# and DeltaS#, were also determined for oximolysis reaction.

Acetylthiocholine↗

In vitro characterization of cholinesterases in the earthworm Eisenia andrei.

Assessment of pollution impact in soil ecosystems has become a priority and interest has grown concerning the use of invertebrates as sentinel organisms. Inhibition of cholinesterase (ChE) activity has a great potential as a biomarker of pesticide exposure, and we evaluated the ChE kinetic parameters in the earthworm Eisenia andrei in the presence of acetylthiocholine (ASCh), proprionylthiocholine (PSCh) and butyrylthiocholine (BSCh). The highest ChE activity was found in the presence of ASCh and PSCh (42.45 and 49.82 nmol min(-1) mg protein(-1), respectively). BSCh was hydrolyzed at a rate of 4.04 nmol min(-1) mg protein(-1), but the time course did not reach a plateau under our experimental conditions. Km values were 0.142+/-0.006 and 0.183+/-0.053 mM for ASCh and PSCh, respectively. ASCh and PSCh hydrolysis were significantly inhibited by eserine (IC50 values were 1.44 x 10(-8) and 1.20 x 10(-8) M, respectively) and by carbaryl (IC50 values of 5.75 x 10(-9) and 4.79 x 10(-9) M). The presence of different ChEs in tissues from E. andrei was assessed by using selective inhibitors for AChE (BW284c51) and BChE (iso-OMPA). BW284c51 strongly reduced ASCh and PSCh hydrolysis and slightly affected that of BSCh, while iso-OMPA was without effect in all cases.

Acetylthiocholine↗