In vivo NIR imaging with CdTe/CdSe quantum dots entrapped in PLGA nanospheres

Luminescent near-infrared (NIR) CdTe/CdSe QDs were synthesized and encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanospheres to prepare stable and biocompatible QDs-loaded nanospheres for in vivo imaging. QDs were encapsulated with PLGA nanospheres by a solid dispersion method and optimized to have high fluorescence intensity for in vivo imaging detection. The resultant QDs-loaded PLGA nanospheres were characterized by various analytical techniques such as UV–Vis measurement, dynamic light scattering (DLS), fluorescence spectroscopy, and transmission electron microscopy (TEM). Finally, we evaluated toxicity and body distribution of QDs loaded in PLGA nanospheres in vitro and in vivo, respectively. From the results, the QDs loaded in PLGA nanospheres were spherical and showed a diameter range of 135.0–162.3 nm in size. The QD nanospheres increased their stability against photooxidation and photobleaching, which have the high potential for applications in biomedical imaging. We have also attained non-invasive in vivo imaging with light photons, representing an intriguing avenue for obtaining biological information by the use of NIR light.

Body distribution and sensitivity of QDs loaded-PLGA nanospheres were measured in SKH1 mice. The strong signal from the fluorescent tissue distinguished it from the autofluorescence of the skin at low concentration. The relatively long-term fluorescence of the QDs loaded in relatively long-term fluorescence of the QDs loaded in PLGA nanospheres in vivo was attributed to the stability of the nanosphere in physiological environments.Figure optionsDownload high-quality image (99 K)Download as PowerPoint slideResearch highlights
► The type II CdTe/CdSe core/shell QDs were entrapped in PLGA nanospheres.
► The QDs-loaded PLGA nanospheres were stable in different conditions.
► Cytotoxicity of QDs-loaded PLGA nanospheres was comparable with that of empty PLGA nanospheres at least for 48 h treatment.
► The fluorescent signals of the QDs-loaded PLGA nanospheres were observed in the whole body of mice for 24 h using non-invasive imaging technique.