Exploiting the UV excited size-dependent emission of PDMS-coated CdTe quantum dots for in vitro simultaneous multicolor imaging of HepG2 cellular organelles

Abstract

Multicolor bioimaging can be referred to as the imaging method that non-invasively visualizes biological processes using fluorophores. Over the years, this technique has been primarily used in the areas of diagnostic and theranostic applications such as the detection of pathogens, identification of disease-specific markers, and cancer detection. Fluorophores such as organic dyes are widely used in bioimaging studies. However, organic dyes exhibit a major limitation of excitation and emission spectral overlap, especially when multispectral bioimaging is considered. Quantum dots (QDs), in contrast, hold great potential due to their properties such as size-tunable narrow emission, single excitation in UV, photo and chemical stability, high fluorescence lifetime, simple surface modification process, etc. Thus, QDs can be a good alternative to traditional fluorophores for bioimaging applications. Herein, the previously reported poly dimethyl siloxane (PDMS)-coated CdTe QDs (PQDs) are used to simultaneously image cellular organelles such as lysosomes, mitochondria, nucleus, and actin of HepG2. Briefly, blue, green, yellow, and orange PQDs are conjugated to CD68 ab. (Lysosomes), mitochondria ab., nuclear antigen ab. and smooth muscle actin ab. respectively using EDC-NHS chemistry. The intracellular organelle targeting of the conjugated QDs is assessed by colocalization with the commercially available dyes. Finally, PQD-conjugates are used to simultaneously image four cellular organelles of HepG2 at an excitation wavelength of 405 nm. The present study demonstrates the potential of PQDs as a fluorophore in simultaneous multicolor bioimaging.