Functionalized Gold Nanorod Probes: A Sophisticated Design of SERS Immunoassay for Biodetection in Complex Media.

Surface-enhanced Raman scattering (SERS) probes offer considerable opportunities in label-based biosensing and analysis. However, achieving specific and reproducible performance, where low detection limits are needed in complex media, remains a challenge. Herein, we present a general strategy employing gold nanorod SERS probes and rationally designed surface chemistry involving protein resistant layers and antibodies to allow for the selective detection of species in complex media. By utilizing the ability of gold nanorods for selective surface modification, Raman reporters (4-mercaptobenzoic acid) were attached to the tips. Importantly, the sides of the nanorods were modified using a mixed layer of two different length stabilizing ligands (carboxyl-terminated oligo ethylene glycols) to ensure colloidal stability, while antibodies were attached to the stabilizing ligands. The nanoparticle interfacial design improves the colloidal stability, unlocks the capability of the probes for targeting biomolecules in complex matrices, and gives the probes the high SERS efficiency. The utility of this probe is demonstrated herein via the detection of Salmonella bacteria at the single bacterium level in complex food matrices using an anti-Salmonella IgG antibody-conjugated probe. The modular nature of the surface chemistry enables the SERS probes to be employed with a molecularly diverse range of biorecognition species (e.g., antibodies and peptides) for many different analytes, thus opening up new opportunities for efficient biosensing applications.

A label-free shotgun proteomics analysis of macadamia nut.

In this study, we present a systematic proteomic overview of macadamia nut using a label-free shotgun proteomic approach. We identified 947 proteins in 723 clusters and gene ontology analysis revealed proteins across 46 functional categories including carbohydrate metabolism (10%), protein metabolic processes (5%), amino acid metabolism (4%), transport (4%), stress response (3%), lipid metabolism (3%), protein folding (3%) and defense response (1.4%). The defense response proteins accounted for 24% of the total peptide abundance. The vicilin-like macadamia antimicrobial peptides 2-3 (MiAMP2) was the most abundant protein, followed by glyceraldehyde-3-phosphate dehydrogenase 3, 11S legumin-like protein, 2-phospho-D-glycerate hydrolase and heat shock 70 kDa protein among others. The cascading of amino acid and carbohydrate metabolic pathways in macadamia nut were constructed against reference maps from KEGG and proposed for the first time. Results were also indicative of useful protein candidates with possible allergenic potential and cross-reactivity in macadamia nut. The in-silico analysis revealed homology and linear epitope similarities to known allergens such as conglutin ß allergen from lupin, Jug r2 vicilin allergens from walnut, Ara h3 11S globulin from peanut, small rubber particle protein Hev b3, hevein, enolase 2, HSP 70kDa Cla h4, Der f28 allergen, and methylglyoxalases. Label-free shotgun proteomics reveal valuable insights into the genetic and biological makeup of macadamia nut proteome and provide guidance on protein candidates with allergenic potential for further immunological investigation. Data are available via ProteomeXchange with identifier PXD015364.

Food Allergen Management in Australia.

Food allergies are increasing globally, including numbers of allergens, the sensitization rate, and the prevalence rate. To protect food-allergic individuals in the community, food allergies need to be appropriately managed. This paper describes current Australian food allergen management practices. In Australia, the prevalence of food allergies, the anaphylaxis rate, and the fatal anaphylaxis rate are among the highest in the world. Interagency and stakeholder collaboration is facilitated and enhanced as Australia moves through past, current, and ongoing food allergen challenges. As a result, Australia has been a global leader in regulating the labeling of common allergens in packaged foods and their disclosure in foods not required to bear a label. Moreover, the food industry in Australia and New Zealand has developed a unique food allergen risk management tool, the Voluntary Incidental Trace Allergen Labelling program, which is managed by the Allergen Bureau. This paper summarizes insights and information provided by the major stakeholders involved to protect food-allergic consumers from any allergic reaction. Stakeholders include government; consumer protection, regulation, and enforcement agencies; the food industry; and food allergen testing and food allergen/allergy research bodies in Australia. The ongoing goal of all stakeholders in food allergen management in Australia is to promote best practice food allergen management procedures and provide a wide choice of foods, while enabling allergic consumers to manage their food allergies and reduce the risk of an allergic reaction.

Quantitative analysis of species specificity of two anti-parvalbumin antibodies for detecting southern hemisphere fish species demonstrating strong phylogenetic association.

This study aimed to develop a novel approach to determine the correlation between the parvalbumin (PAV) contents and their corresponding immunoreactivity (detectability) in southern hemisphere fish species. The immuno-detected PAV contents of the test fish species were estimated by a quantitative SDS-PAGE. A quantitative Enzyme-Linked ImmunoSorbent Assay (ELISA) was formatted to assess relative immunoreactivity of PAV. Sixteen species (forty-three percent) displayed a positive correlation with the anti-cod PAV polyclonal antibody, but no correlation with the anti-carp PAV monoclonal antibody. There was a strong phylogenetic association of the PAV immunoreactivity. Species from the order of Perciformes showed strong binding with both antibodies; whereas species from Salmoniformes, Ophidiiformes, Scombriformes, Scorpaeniformes, and Tetraodontiformes showed weak or no binding. This approach showed for the first time a statistical correlation between the PAV content and the immunoreactivity and allowed to rank the relative species/order specificity of the two antibodies for the southern hemisphere fish PAV.

Development of an ELISA to detect clenbuterol in swine products using a new approach for hapten design.

This research outlines the application of an enzyme-linked immunosorbent assay (ELISA) for the analysis of clenbuterol in animal products. Our assay showed good sensitivity for clenbuterol (0.4 ng/g or 0.4 ppb) and low detection limit (0.09 ng/g or 0.09 ppb). A low cross-reactivity for other ß2-agonist drugs such as salbutamol, terbutaline, and epinephrine led to formatting an ELISA kit considered to have a high specificity for clenbuterol. A survey of Ho Chi Minh City pork market was conducted as part of the validation of our ELISA. ELISA results showed a surprisingly high value of contamination. However, it will be necessary to conduct a more statistically valid replicated survey with evaluation by other instrumental methods to obtain a definite conclusion. This ELISA kit will be used to monitor growth promoter residues in Vietnam's animal products.

Purification and characterization of Ara h1 and Ara h3 from four peanut market types revealed higher order oligomeric structures.

This study aimed to purify and characterize the peanut allergens Ara h1 and Ara h3 from four cultivars that represent the four major market types to provide better understanding of the molecular organization of oligomers in different market types. The chromatographic profiles of Ara h1 and Ara h3 from the four cultivars obtained from anion exchange chromatography were similar. However, they differed in the distribution of trimeric and hexameric structures of Ara h3 isolated by size exclusion chromatography. The Menzies (Runner market type) and Walter (Spanish market type) cultivars, wherein Ara h3 proteins consist of two acidic subunits, exhibited trimeric and hexameric conformations proportionally. However, the Middleton (Virginia market type) and Kelinci (Valencia market type) cultivars, wherein Ara h3 proteins consist of three acidic subunits, showed predominantly a hexameric structure. The oligomeric structures of the purified Ara h1 demonstrated strong IgE binding properties, whereas the allergenic property of the oligomeric Ara h3 could not be performed due to lack of availability of specific IgE. In addition, the polyclonal antibodies raised against the purified Ara h1 and Ara h3 showed highly specific binding to their respective antigens.

Genotype-by-environment interaction affects the essential mineral composition of peanut (Arachis hypogaea L.) kernels.

The concentrations of 15 essential minerals (B, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Se, and Zn) in kernels of nine diverse peanut genotypes, which were cultivated in five distinct growing environments, were analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and -mass spectrometry (ICP-MS). The effects of genotype, environment, and genotype-by-environment (G × E) interactions were significant (P < 0.05) for all elements excluding Cr. Genetic control of mineral composition was demonstrated by large (P < 0.05) genotypic differences in Ca, Mo, K, Na, and P contents, and clustering of some genotypes in environment-centered principal components analysis (PCA) along axes comprising both macro (Ca, Mg, P, and K)- and microelements (Co, Cu, Fe, Mn, and Zn). Mo and Na concentrations were strongly influenced (P < 0.05) by the growing environment, with very high levels measured in samples from Bundaberg. The results confirm that that there is breeding potential for several important minerals in peanuts, although significant G × E interactions will complicate the response to selection. From a practical viewpoint, combining genetic improvement with agronomic management may be a useful strategy to consistently achieve desirable mineral concentrations in peanut kernels.