A quantum dot - immunoglobulin conjugate specific for pig IgG, was obtained by carbodiimide chemistry. We used a
Western blot technique for detecting specific antibodies against <i>Actinobacillus pleuropneumoniae</i> (<i>A. pp</i>), which cause
porcine pleuropneumonia. The antigen used in this technique was Apx haemolysin which is an important virulence factor of
<i>A. pp</i> and it induces protective immunity in vaccined pigs. The detection on Western blot membrane was possible at 1/50
dilution of quantum dot conjugate at a dilution of pig serum till 1/6400. The results for pig serum demonstrated a higher
sensitivity of QD-based Western blot technique for the presence of antibodies specific for Apx haemolysin in comparison
with similar classical techniques (with coloured substrate for enzyme present in secondary antibody conjugate).
We report the functionalization of Si/SiO<sub>2</sub> Quantum Dots (QDs) synthesised by laser ablation. Our interest has been to
increase the affinity of the QDs surface for organic substances, in order to obtain QD-immunoglobulin conjugates,
particularly for biolabeling. We have studied the UV-induced graft polymerization of the freestanding nanoparticles.
High resolution transmission electron microscopy and laser granulometry, were used to obtain information on particle
and cluster size distribution, degree of agglomeration, etc. The polymer-dot complexes appeared as relatively well-defined
clusters, QDs being surrounded by a polymer layer with thickness 3-10 nm. The size of the primary clusters was
in the range 60-500 nm. The polymerization and filtration process (0.1 μm pores) involved a diminution of the clusters
size in the range of 18-65 nm, and moreover, by a subsequent dialyses process the cluster size decreased to 5-15 nm.