Ultrasensitive immunoassays based on biotin–streptavidin amplified system for quantitative determination of family zearalenones

In this work, based on a newly obtained monoclonal antibody (MAb) against zearalenone (ZEN) and biotin–streptavidin system (BSAS) for signal amplification, two sensitive and rapid immunoassay formats including biotin–streptavidin amplified enzyme-linked immunosorbent assay (BA-ELISA) and biotin–streptavidin amplified fluorescence-linked immunosorbent assay (BA-FLISA), were developed for family zearalenones (ZENs) determination. And the limits of detection (LODs) of ZEN were 0.02 ng mL⁻¹ and 0.10 ng mL⁻¹ for BA-ELISA and BA-FLISA respectively. Using the BA-ELISA platform the half maximal inhibitory concentrations (IC₅₀) were 0.18 ng mL⁻¹ for ZEN, 0.39 ng mL⁻¹ for α-zearalenol (α-ZOL), 0.46 ng mL⁻¹ for β-zearalenol (β-ZOL), 0.30 ng mL⁻¹ for zearalanone (ZAN), 0.30 ng mL⁻¹ for α-zearalanol (α-ZAL), and 0.73 ng mL⁻¹ for β-zearalanol (β-ZAL). With the broad specificity, the developed immunoassays could be used as sensitive and valuable tools for detection of family ZENs. Additionally, the suitability of the proposed immunoassays for its application to corn flour and corn based baby food has also been investigated.     

Ultrasonic-assisted synthesis and strepavidin conjugation of amino-magnetic nanoparticles

MNPs are widely used in biotechnology, magnetic resonance imaging, catalysis and other areas. In this paper, we propose a simple, quick, inexpensive and efficient way to prepare amino-MNPs with sonication-assisted process. The amino-MNPs prepared by hydrolyzing TEOS and APS were characterized by SEM, TEM and FTIR. Conjugation of SA and amino-MNPs was also studied. The biotin bound capacity of prepared SA coated amino-MNPs was 1.824 nmol/mg, which well meet the need of biological application.     

Effects of pulsed electric fields on water-soluble vitamins and ACE inhibitory peptides added to a mixed orange juice and milk beverage

The effects of pulsed electric fields technology (15–40 kV/cm; 0–700 μs) and thermal processing (84 °C and 95 °C, 15–120 s) were studied on an orange juice and milk mixed beverage fortified with water-soluble vitamins (biotin, folic acid, pantothenic acid and riboflavin) and angiotensin-I-converting enzyme (ACE) inhibitory peptides. The evaluation of the technologies was carried out from two points of view: effect of treatments and effect of storage (4 °C, 81 days). The results confirmed the stability of the vitamins and the ACE inhibitory activity after the PEF treatment and during storage.     

Enhanced hypoglycemic effect of biotin-modified liposomes loading insulin: effect of formulation variables,intracellular trafficking,and cytotoxicity

Peroral protein/peptide delivery has been one of the most challenging, but encouraging topics in pharmaceutics. This article was intended to explore the potential of biotin-modified liposomes (BLPs) as oral insulin delivery carriers. By incorporating biotin-DSPE into the lipid bilayer, we prepared BLPs using reverse evaporation/sonication method. We investigated hypoglycemic effects in normal rats after oral administration of BLPs, and the possible absorption mechanism by a series of in vitro tests. The relative pharmacological bioavailability of BLPs was up to 11.04% that was as much as 5.28 folds of conventional liposomes (CLPs). The results showed that the enhanced oral absorption of insulin mainly attributed to biotin ligand-mediated endocytosis. The results provided proof of BLPs as effective carriers for oral insulin delivery.     

Charge transport effects in ferrocene-streptavidin multilayers immobilized on electrode surfaces

Streptavidin (SAv) has been modified by covalent coupling of ferrocene (Fc) electron-relay groups to lysine-residues of the protein backbone. Reagent ratios were varied to obtain conjugates with three to 16 Fc groups per SAv. Biotin was covalently attached to gold electrodes for the anchoring of the conjugate monolayers. A method was devised to produce in situ bisbiotin functionalities that efficiently cross-linked Fc₁₆SAv to form multilayer electrode coatings. The electrochemical charge transport properties of the coatings were examined by cyclic voltammetry. The characteristic current density i_E measuring the rate of charge transport was 1 mA cm⁻² for one monolayer of Fc₁₆SAv. It was found that the transport of electrochemical charge through the Fc-containing SAv system is a diffusion-like process, as evidenced by the proportionality of the peak current and the square root of sufficiently high scan rate, and the inverse dependence of i_E on the number (thickness) of Fc₁₆SAv layers.     

Sensitive dual-labeled electrochemical aptasensor for simultaneous detection of multi-antibiotics in milk

In this work, a dual-labeled multiple aptasensor that can simultaneously detect multiple antibiotics was constructed, with kanamycin (KAN) and tobramycin (TOB) used as the model analytes. The aptasensor reported here featured three key elements, namely the RNA-based aptamer strands, semiconductor quantum dots (QDs), and gold nanoshells (AuNSs). Due to the high-affinity pairing between streptavidin (SA) and biotin (Bio), the two biotinylated aptamers (kanamycin aptamer, KAP; tobramycin aptamer, TAP) responsible for the specific recognition of KAN and TOB were conjugated to SA-coated cadmium sulfide (CdS) and lead sulfide (PbS) QDs, respectively for the syntheses of KAP-Bio-SA-CdS and TAP-Bio-SA-PdS composites. Moreover, the AuNSs had a very high loading efficiency for the as-prepared two composites on the gold electrode surface due to their outstanding surface-area-to-volume ratio. In the presence of target antibiotics, CdS and PbS QDs were released from AuNSs followed by dissolution into their respective metal ions for stripping analysis by differential pulse voltammetry (DPV). As a result, intensified signals from DPV peaks were obtained due to the large amount of the metal ion labels dissolved in the solution. The devised aptasensor exhibited wider detection linear range (KAN, 1–4 × 10² nM; TOB, 1–1 × 10⁴ nM) and lower detection limits (KAN, 0.12 nM; TOB, 0.49 nM) compared to the previously reported sensors. Furthermore, the detection of KAN and TOB spiked in milk samples was successfully demonstrated. Therefore, the proposed aptasensor provides a novel sensitive platform for multi-antibiotics detection.