Cancer remains one of the world's most devastating diseases with millions of fatalities and new cases every year. In this work, we attempted to develop a facile "
enzyme-free" fluoroimmunoassay based on the novel
nanoconjugates composed of CdS
quantum dots (QDs) as the fluorescent inorganic core and an antibody-modified
polysaccharide as the organic shell, modeling their possible application for the in vitro diagnosis of
non-Hodgkin lymphoma (NHL)
cancer.
Chitosan was conjugated with an anti-CD20 polyclonal antibody (pAbCD20) by the formation of covalent
amide bonds. In the sequence, these
chitosan-antibody conjugates were utilized as direct
ligands for the surface biofunctionalization of CdS QDs (CdS/
chitosan-pAbCD20) using a single-step colloidal process in aqueous medium at room temperature. The most relevant physico-chemical properties of these
nanoconjugates were assessed by morphological and spectroscopic techniques. The results indicated that CdS nanocrystals were produced with an average diameter of 2.5 nm and with cubic
zinc blende crystalline nanostructure. The CdS-
immunoconjugates (CdS/
chitosan-pAbCD20) presented colloidal hydrodynamic diameter (HD) of 15.0 ± 1.2n m. In addition, the results evidenced that the "
enzyme-free" QD-linked
immunosorbent assay (QLISA) was effective for the in vitro detection against the
antigen CD20 (aCD20) based on fluorescent behavior of the CdS
nanoconjugates. Moreover, the CdS-
immunoconjugates were successfully used for fluorescence bioimaging of NHL
cancer cells. Finally, the cell viability results using different cell cultures based on LDH, MTT and
Resazurin bio-assays have demonstrated no cytotoxicity of the new CdS-
chitosan bioconjugates relative to the standard controls. Thus, CdS conjugates may offer a promising platform for the future development of in vitro and in vivo applications for the detection and diagnosis of NHL
cancer cells.