Anti-Avidin polyclonal antibody [FITC]

The combined pressure (0.1 and 600 MPa) and thermal (30, 65, 75, 90, and 105 degrees C) treatment effects on the binding properties of egg-white avidin were investigated using fluorescence spectroscopy titrations with fluorescein-labeled biotin for various holding times (up to 45 min). Pressure treatment was carried out in a high-pressure kinetic tester whereas heat treatment was conducted using metal tubes in a temperature-controlled oil bath. Avidin binding activity and strength decreased by approximately three orders of magnitude with increases in temperature and holding time, while the binding free energy (-52.3 +/- 0.47 kJ/mol) remained unaffected by high-pressure (600 MPa at 30 degrees C) treatment. The thermal inactivation rate constant ranged from 0.009 to 0.793 per min at 65-105 degrees C, 0.1 MPa. Combined pressure (600 MPa)-thermal (65-105 degrees C) treatment reduced the corresponding values by a factor of two to nine, resulting in inactivation rates that ranged from 0.001 to 0.422 per min. Activation energies for avidin inactivation were 120 +/- 10 and 149 +/- 8 kJ/mol for thermal and combined pressure-thermal treatment, respectively. In conclusion, while heat treatment alone destroyed biotin binding strength of avidin, combined pressure, and heat exhibited antagonistic effects on avidin-biotin binding energies. Practical Applications Heat and pressure can have synergistic, additive, or antagonistic effects on food components. The synergistic effect is important from food safety aspect whereas antagonistic effect is desirable to retain food quality attributes during food processing. The parameters of reaction kinetic models, more specifically rate constant and activation energy can be used to evaluate the interactions of heat and pressure during food processing. Egg-white avidin has been selected in this study to evaluate the interaction between heat and pressure. Information obtained from this study can be used to preserve egg-white avidin binding activity for various applications including food formulations, biochemical assays and preservation, due to its enormously high binding ability with biotin.

In this work, we first introduced beta-cyclodextrin-functionalized CdS nanorod (beta-CD@CdS NR)/WS2 nanosheet (NS) heterostructures as dual-functional building blocks for designing an ultrasensitive photoelectrochemical bioassay of microRNA-21 based on cyclic strand displacement reaction (SDR)-mediated Cu2+ quenching and host-guest interaction between beta-CD and adamantane (ADA), in which beta-CD@CdS NR)/WS2 NS heterojunction serves as a signaling and linking unit, and avidin-labeled CuO (Avidin-CuO) nanoparticle as a quenching unit. In the presence of microRNA-21, ADA-labeled hairpin DNA1 was unfolded by DNA hybridization and triggered SDR cycling with the aid of biotin-labeled hairpin DNA2, which generated plenty of double-stranded DNA structures with biotin molecules at the outer terminal point of dsDNA. When Avidin-CuO was immobilized onto the electrode surface via biotin-avidin affinity binding and then dissolved by hydrochloric acid, the released Cu2+ could react with the CdS NR to generate CuxS, leading to a decreased photocurrent response. Under the optimized conditions, this biosensor displayed desirable linearity in the range from 0.1 fM to 10 pM, a low detection limit of 25.1 aM and satisfactory selectivity, and was applied to microRNA-21 analysis in serum samples, holding great potential for early diagnosis of some cancers. (C) 2019 Elsevier Ltd. All rights reserved.