Supporting Information Functionalization of Quantum Dots with Multidentate Zwitterionic Ligands: Impact on Cellular Interaction and Cytotoxicity Minghao Sun,‡ Likun Yang,‡ Purnima Jose, Li Wang and Jamal Zweit* Center for Molecular Imaging, Department of Radiology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA, 23298.

Fig. S1 Chemical structure of polymer ligand 10.

Fig. S2 1H NMR of model compound LA-DMEDA.

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Fig. S3 1H NMR of polymer 3c (x/y=1/1).

Fig. S4 1H NMR of polymer 4c (x/y=1/1).

CC CCOONNHH

HHNNOO

SSSS

OOHHNN

NN

SSOO OO

OO

xx yy****

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Fig. S5 1H NMR of polymer 5c (x/y=1/1).

Fig. S6 1H NMR of polymer 7 (x/y/z=5/3/2).

CC CCOONNHH

HHNNOO

HHSSHHSS

OOHHNN

NN

SSOO OO

OO

xx yy****

CC CCOONNHH

HHNNOO

SSSS

OOHHNN

NN

xx yy****

ZZCC OO

HHNN

OO

HHNN

OO

OO

nn

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Fig. S7 1H NMR of polymer 8 (x/y/z=5/3/2).

Fig. S8 1H NMR of polymer 9 (x/y/z=5/3/2).

CC CCOONNHH

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SSSS

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NN

xx yy****

ZZCC OO

HHNN

OO

HHNN

OO

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nn

SSOO

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HHSSHHSS

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NN

xx yy****

ZZCC OO

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OOOO

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Fig. S9 TEM of CdSe/ZnS QDs before (a) and after (b) modification with multidentate zwitterionic ligands.

a

b

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Fig. S10 Absorption (a), emission (b) and excitation (c) spectra of QDs before (in CHCl3) and after ligand exchange (in H2O).

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QD before ligand exchange QD after ligand exchange

550 600 650

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nsity

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)

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QD before ligand exchange Qd after lignad exchange

300 400 500

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nsity

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QD before ligand exchange QD after ligand exchange

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Fig. S11 Zeta potentials of QD-a to QD-e.

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QD-d: -40.4 mv

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QD-b: -31.6mv

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QD-a: -25.9 mv

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QD-c: -30.6 mv

QD-e: -54.8 mv

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Fig. S12 Fluorescent microscopy of COLO 205, KB 3-1, and HEK 293 cell lines incubated with QD-a, QD-c and QD-d at 50 nM for 4 hrs. (A) COLO 205-QD-a; (B) COLO 205-QD-c; (C) COLO 205-QD-d, (D) KB 3-1-QD-a; (E) KB 3-1-QD-c; (F) KB 3-1-QD-d, (G) HEK 293-QD-a; (H) HEK 293-QD-c; (I) HEK 293-QD-d.

Fig. S13 Gel electrophoresis of cRGD-QD-9 before (a) and after (b) incubating with mouse plasma.

A B C

D E F

G H I

QD-a QD-c QD-d

a b

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A

B

C

D

Fig. S14 Fluorescent microscopy of U87MG incubated (1 hr) with cRGD-QD-9 (A) without or (B) with free cRGD blocking (left) and relevant bright field images (right). Fluorescent microscopy of U87MG incubated (4 hrs) with cRGD-QD-9 (C) without or (D) with free RGD blocking (left) and relative bright field images (right).

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