S4

Supporting Information:

Cytotoxicity and fluorescence studies of silica-coated CdSe quantum dots for bioimaging applications

Muthunayagam Vibin 1, Ramachandran Vinayakan 2, Annie John3, Vijayamma Raji 1, Chellappan S. Rejiya 1, Naresh S. Vinesh 1, Annie Abraham1*

1Department of Biochemistry, University of Kerala, Thiruvananthapuram, Kerala, India.

2Photosciences and Photonics, National Institute for Interdisciplinary Science and Technology (CSIR), Thiruvananthapuram, Kerala, India.

3Sree Chitra Tirunal Institute of Medical Sciences and Technology, Biomedical

Technology Wing, Thiruvananthapuram, Kerala, India.

Table of Content / Page No.
1.  Characterisation of colloidal properties of silica-coated CdSe QDs / S1
2.  Cytotoxicity studies on A431 cell lines-MTT assay / S3
3.  In vitro fluorescence images of silica-coated CdSe QDs on SiHa cells / S4
4.  Elemental analysis- ESEM-EDS / S4

1.  Characterisation of colloidal properties of silica-coated CdSe QDs

Fig. S1. Absorption (left) and emission (right) spectra of silica-coated CdSe QDs in PBS buffer under different pH conditions.
Fig. S2. Absorption (left) and emission (right) spectra of silica-coated CdSe QDs, recorded in PBS buffer (pH 7.3) of different ionic strengths.
Fig. S3. (left) HRTEM showing the presence of thin silica shell over CdSe core. (right) EDS spectra confirming the presence of Si in the nanoparticles structure.
Fig. S4. (left) FTIR spectra of CdSe QDs before and after over coating with silica; (right) A theoretical predication of silica shell thickness based on arrangement of APS molecules.
Fig. S5. PL spectra (stability) of silica-coated CdSe QDs in medium (DMEM) as a function of time intervals: (a-c) Emission of 24, 48 and72 h (d) Emission of medium alone.

2.  Cytotoxicity studies on A431 cell lines-MTT assay

Fig. S6. Results of the MTT assay of mitochondrial activity of A431 cells exposed to silica-coated CdSe QDs as a function of concentration and incubation time. The viability of the control cells was considered 100%. The results are means ±SD from four independent experiments, it confirmed that silica-coated QDs are non toxic.

3.  In vitro fluorescence images of silica-coated CdSe QDs on SiHa cells

Fig. S7. Luminescence images of cultured SiHa cells incubated with silica-coated CdSe QDs.The QDs and the DAPI-stained nuclei (blue) were recorded with fluorescence microscope (20x magnification).

4.  Elemental analysis-ESEM-EDS

Fig. S8. ESEM-EDS showing the confirmative distribution of silica-coated CdSe QDs in the cryosections of the liver tissue after 30 minutes post injection: a) ESEM image b) EDS data.