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Abstract: Staphyloccocus aureus is reported to be one of the most frequent pathogens involved in food-borne diseases associated with dairy products, especially with raw milk cheese. Some strains produce enterotoxins as Staphylococcal enterotoxin A (SEA) which is involved in 75% of food poisoning outbreaks. Actually few methods are both sensitive and specific enough for confirming the diagnosis of staphylococcal food poisoning. In this work, an Enzyme-Linked ImmunoSorbent Assay (ELISA) was set up and optimised to detect SEA in milk and cheese. Various anti-SEA antibodies: polyclonal sera, anti-peptide polyclonal sera and monoclonal antibodies, used for the capture and or detection steps were compared and analysed. The mouse anti-whole SEA polyclonal serum, used as detection detected 32 pg/ml SEA in buffer and 64 pg/ml in milk. These concentrations were well under the limit set for food safety. This assay was also highly specific of SEA and no cross-reaction was observed with the other staphylococcal enterotoxins. In contaminated cheese samples the time of enterotoxin extraction was reduced by using ultrafiltration method instead of dialysis and the detection limits were 1.5–2.5 and 1.9–3 times more sensitive than a commercial kit and the official method, respectively. Preliminary study of SEA detection with the piezoelectric immunosensor allowed detecting and quantifying SEA within 10 min in unprocessed food but the sensitivity was not sufficient. The ELISA assay with mouse antibodies is likely suitable for SEA routine detection not only in dairy product but also in various foods as sauce and liver mousse. [Copyright &y& Elsevier]

We describe herein the synthesis of generation 4 (G4) poly(amidoamine) (PAMAM) dendrimers bearing (1) a nitroaniline derivative as an NMR probe, (2) (5-cyclopentadienyl)iron dicarbonyl succinimidato complexes as infrared probes for carbonyl metallo immunoassay, (3) acetamide groups for increased solubility, and (4) hydrazide functions at the extremity of five-carbon atom spacer arms for the labeling of aldehyde-containing molecules. The step-by-step building of these multifunctionalized dendrimers was monitored by 1H NMR spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry. Substitution of terminal amine groups of PAMAM dendrimers with appropriate functional groups provides complex dendrimeric structures with a wide range of applications. The final goal of this study is the development of new reagents suitable for the metal−carbonyl multilabeling of immunological reagents such as antibodies. [ABSTRACT FROM AUTHOR]

In the aim of protecting stainless steel surfaces against protein and/or bacterial adhesion, thin films including the glycosidase hen egg white lysozyme (HEWL) and/or the synthetic polymer poly(ethylene glycol) (PEG) were covalently coated onto flat substrates by wet chemical processes. Chemical grafting of both species was carried out by covalent binding to surfaces pretreated by the polyamine poly(ethylene imine) (PEI). Surfaces were characterized at each step of functionalization by means of reflection−absorption infrared spectroscopy by modulation of polarization (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS) to determine the atomic and molecular composition of the interfaces, respectively. Then, the ability of the so-modified surfaces to prevent protein adsorption and bacterial adhesion together with their biocide properties were demonstrated by three local tests employing bovine serum albumin (BSA), and the bacteria Listeria ivanoviiand Micrococcus luteus. A new test was implemented to assess the local enzymatic properties of HEWL. Cografting of PEG and HEWL resulted in a surface with both antiadhesion and antibacterial properties. [ABSTRACT FROM AUTHOR]

Covalent embedding of a (η6-arene) ruthenium(ii) complex into the protein papain gives rise to a metalloenzyme displaying a catalytic efficiency for a Lewis acid-mediated catalysed Diels–Alder reaction enhanced by two orders of magnitude in water. [ABSTRACT FROM AUTHOR]