Submicrometer fluorescent polystyrene (PS) particles have been synthesized via miniemulsion polymerization using CdSe/ZnS core-shell quantum dots (QDs). The influence of QD concentration, QD coating (either trioctylphosphine oxide (TOPO)-coated or vinyl-functionalized), and surfactant concentration on the polymerization kinetics and the photoluminescence properties of the prepared particles has been analyzed. Polymerization kinetics were not altered by the presence of QDs, whatever their surface coating. Latexes exhibited particle sizes ranging from 100 to 350 nm, depending on surfactant concentration, and a narrow particle size distribution was obtained in all cases. The fluorescence signal of the particles increased with the number of incorporated TOPO-coated QDs. The slight red shift of the emission maximum was correlated with phase separation between PS and QDs, which occurred during the polymerization, locating the QDs in the vicinity of the particle/water interface. QD-tagged particles displayed higher fluorescence intensity with TOPO-coated QDs compared to those with the vinyl moiety. The obtained fluorescent particles open up new opportunities for a variety of applications in biotechnology.

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Mass spectrometry (MS) in Selected Reaction Monitoring (SRM) mode is proposed for in-depth characterisation of microorganisms in a multiplexed analysis. Within 60–80 minutes, the SRM method performs microbial identification (I), antibiotic-resistance detection (R), virulence assessment (V) and it provides epidemiological typing information (T). This SRM application is illustrated by the analysis of the human pathogen Staphylococcus aureus, demonstrating its promise for rapid characterisation of bacteria from positive blood cultures of sepsis patients.

The aim of this work is to demonstrate the ability of atomic force microscopy (AFM) to detect and to quantify specific immunological reactions between antibodies and antigens, with a view to creating a very sensitive biosensor. A monolayer of antiferritin antibodies was adsorbed onto alkyl silane modified silicon oxide substrates, which were characterized by X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The sensitivity limit for antibody detection was quantified by radioimmunoassay (RIA) and compared to that obtained by enzyme linked immuno sorbent assay (ELISA) and by AFM after antibody binding with colloidal gold labeled conjugates. In this latter case, substrate modification after reaction was checked by measuring the surface roughness (R rms) variations. AFM was found to be more sensitive than RIA, with a detection limit of 0.3 × 10-3 ng of antibodies per mm2. Then, the biosensor performance was investigated using ferritin solutions of various concentrations:  the antibody/antigen reaction was quantified by directly detecting the antigen and measuring surface roughness modifications. Results were compared to sandwich immunoassay techniques. Up to now, AFM has detected a minimum ferritin concentration of 0.06 μg/mL.