Adaptation of Conductometric Monoenzyme Biosensor for Rapid Quantitative Analysis of L-arginine in Dietary Supplements.

The present study reports on the development, adaptation, and optimization of a novel monoenzyme conductometric biosensor based on a recombinant arginine deiminase (ADI) for the determination of arginine in dietary supplements with a high accuracy of results. Aiming for the highly sensitive determination of arginine in real samples, we studied the effect of parameters of the working buffer solution (its pH, buffer capacity, ionic strength, temperature, and protein concentration) on the sensitivity of the biosensor to arginine. Thus, it was determined that the optimal buffer is a 5 mM phosphate buffer solution with pH 6.

Rapid and PCR-free DNA Detection by Nanoaggregation-Enhanced Chemiluminescence.

The aggregation of gold nanoparticles (AuNPs) is known to induce an enhancement of localized surface plasmon resonance due to the coupling of plasmonic fields of adjacent nanoparticles. Here we show that AuNPs aggregation also causes a significant enhancement of chemiluminescence in the presence of luminophores. The phenomenon is used to introduce a rapid and sensitive DNA detection method that does not require amplification.

Microbial separation from a complex matrix by a hand-held microfluidic device.

Through a simple chemical activation of biomolecules present in the outer structures of microbial cells, microorganisms can be rapidly isolated on gold-coated surfaces in a microfluidic device with over 99% capture efficiency. Bacterial and fungal cells can be selectively captured, concentrated and retrieved for further analysis.

Development of Conductometric Sensor Based on 25,27-Di-(5-thio-octyloxy)calix[4]arene-crown-6 for Determination of Ammonium.

The conductometric sensor based on 25,27-di-(5-thio-octyloxy)calix[4]arene-crown-6 was developed for the quantitative analysis of ammonium. The calixarene was immobilized on the surface of the planar interdigitated electrodes by attachment of its dialkyl sulfide groups to the surface of the gold electrodes. The intrinsic ability of the calixarene to capture ammonium was studied in the conductometric measuring mode and by the electrochemical impedance spectroscopy.

Urease-based ISFET biosensor for arginine determination.

In this work a novel biosensor for arginine determination based on the urease inhibition effect has been proposed. Ion-selective field effect transistors were used as transducers. Urease immobilized in glutaraldehyde vapor served as a biorecognition element of the biosensor.