Immunochromatographic Assay Based on Polydopamine-Decorated Iridium Oxide Nanoparticles for the Rapid Detection of Salbutamol in Food Samples.

Salbutamol (SAL), a ß-2 adrenoreceptor agonist, is an unpopular addition to livestock and poultry, causing several side effects to human health. Thus, it is very important to develop a simple and rapid analytical method to screen SAL in the field of food safety. Here, we present an immunochromatographic assay (ICA) method for sensitively detecting SAL with polydopamine-decorated iridium oxide nanoparticles (IrO2@PDA NPs) as a signal tag. The IrO2@PDA with excellent hydrophilicity, biocompatibility, and stability was synthesized by oxidating self-polymerization of dopamine hydrochloride (DAH) on the surface of IrO2 NPs and used to label monoclonal antibodies (mAbs) through simple physical adsorption. Compared with IrO2 NPs, the IrO2@PDA also possessed superior optical properties and higher affinity with mAbs. With the proposed method, the limit of detection for SAL was 0.002 ng/mL, which was improved at least 24-fold and 180-fold compared with the IrO2 NPs-based ICA and conventional gold nanoparticles-based ICA, respectively. Furthermore, the SAL residuals in pork, pork liver, and beef were successfully detected by the developed biosensor and the recoveries ranged from 85.56% to 115.56%. Briefly, this work indicated that the powerful IrO2@PDA-based ICA can significantly improve detection sensitivity and has huge potential for accurate and sensitive detection of harmful small molecules analytes in food safety fields.

Agonistic ß2-Adrenergic Receptor Autoantibodies Characterize the Aqueous Humor of Patients With Primary and Secondary Open-Angle Glaucoma.

Purpose: Agonistic ß2-adrenergic receptor autoantibodies (ß2-agAAbs) were recently observed in sera of patients with ocular hypertension (OHT), primary (POAG), and secondary open-angle glaucoma (SOAG), yet not in healthy controls (HCs). It was the aim of the present study to investigate the presence of ß2-agAAb in aqueous humor (AH) samples of OAG patients and to correlate these with the corresponding ß2-agAAb serum data. Material and Methods: Thirty-nine patients (21 male, 18 female) were recruited from the Department of Ophthalmology, University of Erlangen-Nürnberg: twenty-one POAG, 18 SOAG. Aqueous humor samples were collected during minimal invasive glaucoma surgery. Serum and AH samples were analyzed for ß2-agAAb by a bioassay quantifying the beating rate of cultured cardiomyocyte (cut-off: 2 U). Results: Thirty-six of 39 (92.3%) and 34 of 39 (87.2%) of OAG patients showed a ß2-agAAb in their sera and AH samples, respectively. All ß2-agAAb AH-positive OAG patients were also seropositive. We also observed a ß2-agAAb seropositivity in 95 and 89% of patients with POAG and SOAG, respectively. Beta2-agAAbs were seen in 86% (POAG) and 78% (SOAG) of AH samples. The ß2-agAAb adrenergic activity was increased in the AH of patients with POAG (6.5 ± 1.5 U) when compared with those with SOAG (4.1 ± 1.1 U; p = 0.004). Serum ß2-agAAb adrenergic activity did not differ between the cohorts [POAG (4.5 ± 1.5 U); SOAG (4.6 ± 2.1 U; p=0.458)]. No correlation of the beating rates were observed between serum and AH samples for group and subgroup analyses. Conclusion: The detection of ß2-agAAb in systemic and local circulations supports the hypothesis of a direct functional impact of these agAAbs on ocular G-protein coupled receptors. The high prevalence of ß2-agAAb in serum and AH samples of patients with POAG or SOAG suggests a common role of these AAbs in the etiopathogenesis of glaucoma, independent of open-angle glaucoma subtype.

Highly sensitive detection of clenbuterol using competitive surface-enhanced Raman scattering immunoassay.

In this report, we present a novel approach to detect clenbuterol based on competitive surface-enhanced Raman scattering (SERS) immunoassay. Herein, a SERS nanoprobe that relies on gold nanoparticle (GNP) is labeled by 4,4'-dipyridyl (DP) and clenbuterol antibody, respectively. The detection of clenbuterol is carried out by competitive binding between free clenbuterol and clenbuterol-BSA fastened on the substrate with their antibody labeled on SERS nanoprobes. The present method allows us to detect clenbuterol over a much wider concentration range (0.1-100 pg mL(-1)) with a lower limit of detection (ca. 0.1 pg mL(-1)) than the conventional methods. Furthermore, by the use of this new competitive SERS immunoassay, the clenbuterol-BSA (antigen) is chosen to fasten on the substrate instead of the clenbuterol antibody, which could reduce the cost of the assay. Results demonstrate that the proposed method has the wide potential applications in food safety and agonist control.

Structure of a nanobody-stabilized active state of the ß(2) adrenoceptor.

G protein coupled receptors (GPCRs) exhibit a spectrum of functional behaviours in response to natural and synthetic ligands. Recent crystal structures provide insights into inactive states of several GPCRs. Efforts to obtain an agonist-bound active-state GPCR structure have proven difficult due to the inherent instability of this state in the absence of a G protein. We generated a camelid antibody fragment (nanobody) to the human ß(2) adrenergic receptor (ß(2)AR) that exhibits G protein-like behaviour, and obtained an agonist-bound, active-state crystal structure of the receptor-nanobody complex. Comparison with the inactive ß(2)AR structure reveals subtle changes in the binding pocket; however, these small changes are associated with an 11 Å outward movement of the cytoplasmic end of transmembrane segment 6, and rearrangements of transmembrane segments 5 and 7 that are remarkably similar to those observed in opsin, an active form of rhodopsin. This structure provides insights into the process of agonist binding and activation.