Supporting Information

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1 Supporting Information Wiley-VCH Weinheim, Germany

2 Supporting information: experimental details of the synthesis of the amino-functionalized polymers and nanoparticles used Tailor-made ligands for biocompatible nanoparticles Marija S. Nikolic, Maren Krack, Vesna Aleksandrovic, Andreas Kornowski, Stephan Förster, Horst Weller Synthesis of amino functionalized PEOs of 2000 g/mol In a first step, PEOs (Fluka) with NCO end groups were synthesized according to published procedures with slight changes in the ratios of reactants. Briefly, 2.22 g of monomethyl ether poly(ethylene oxide) (M 2000 g/mol) were dissolved in 20 ml of chloroform and 4.50 ml of hexamethylene diisocyanate (25 mol excess) were added. The reaction mixture was refluxed for 24 h under an inert atmosphere. The obtained NCOmodified PEO was precipitated two times from chloroform using diethyl ether. The NCO-modified PEO was further reacted with diethylenetriamine to obtain PEO- DETA. Thus 1.99 g of PEO-NCO was dissolved in 20 ml of chloroform. To this solution, a solution of 9.44 ml of diethylenetriamine dissolved in 20 ml of chloroform was added stepwise over 2h, after which the reaction mixture was kept at 40 o C for a further 2h. After concentration of the solution, the polymer was precipitated twice from chloroform into diethyl ether and dried under vacuum. The NCO-modified PEO was also further reacted with PEI (M 400g/mol) to obtain PEO-PEI-branched by adding a chloroform solution of PEI. The ratio of PEO to PEI was chosen to yield a molecule with two PEO chains attached to PEI. The reaction mixture was stirred under an inert atmosphere for 12 h at 60 o C. After completion of the reaction, the polymer was precipitated with diethyl ether. Synthesis of amino functionalized PEOs of 5000 g/mol For the synthesis of PEO5000-NCO, the same reaction conditions were used as in the case of PEO of 2000 g/mol, except that a 50 mol excess of hexamethylene diisocyanate was used in this case.

3 For the synthesis of the PEO modified with the short amine, the same ratio of amine:polymer was applied as in a case of PEO of 2000 g/mol. The reaction temperature was 60 o C and reaction mixture was stirred for 12 h. The polymer was precipitated two times from chloroform into diethyl ether and dried under vacuum. To obtain PEO modified with branched poly(ethylene imine), a chloroform solution containing PEO-NCO and PEI (400 g/mol) in a mole ratio 2:1 was refluxed under an inert atmosphere for 24 h. After completion of the reaction, the polymer was precipitated into diethyl ether and dried under vacuum. Synthesis of CdSe/CdS and CdSe/CdS/ZnS nanoparticles The core/shell CdSe/CdS and core/shell/shell CdSe/CdS/ZnS nanoparticles were synthesized according to the published procedures. [1, 2] The synthesis was performed under nitrogen using Schlenk technique. Briefly, 8 g of tri-n-octylphosphine oxide were dried and degassed under vacuum at 180 C for 1 h. Then, after the cooling to 100 C, 5 g hexadecylamine and 0.15 g n-tetradecylphosphonic acid were added, and the drying process was continued at 120 C under vacuum for 20 min. The stock solution of TOPSe prepared by dissolving selenium (0.158 g, 2.0 mmol) in 2 ml of tri-n-octylphosphine, TOP, was added and the mixture was heated to 300 C. The cadmium stock solution (0.12 g of cadmium acetate in 3 ml of TOP) was quickly injected under vigorous stirring, resulting in nucleation of CdSe nanocrystals. Further particle growth was carried out at 270 C. Both cadmium and selenium stock solutions were prepared and stored inside a glove box under nitrogen atmosphere. A CdS shell was grown around CdSe nanocrystals via injection of H 2 S gas. The reaction flask containing a freshly prepared crude solution of CdSe nanocrystals was heated to 140 C. A certain amount of H 2 S gas was slowly injected in 2-ml portions (1 injection per 15 min) through a septum. The nitrogen flow within the Schlenk line was stopped before the injection. The reaction mixture slowly absorbed the H 2 S gas during stirring at 140 C for half an hour. Then the temperature was decreased to 100 C and the solution was stirred for one more hour. The reaction mixture was cooled to 50 C, and 15 ml of chloroform were added. Nanoparticles were precipitated by addition of the methanol, centrifugated and the precipitate was re-dissolved in chloroform. In order to remove excess ligands the washing procedure was repeated twice. The resulting nanoparticle solution was filtrated through 0.2 µm syringe filter before applying the ligand exchange procedure.

4 As for the CdS shell the ZnS shell was grown by injection of H 2 S gas. In a typical recipe 0.3 g of Zn(Ac) 2, (~1.64 mmol) were dissolved in 3 g hexadecylamine. The mixture was dried and degassed at 130 C at vacuum for 1h and then added to a solution of freshly prepared CdSe/CdS nanocrystals at 90 C. The mixture was heated to 220 C and 10 ml of H 2 S were slowly injected above the solution in 2-mL portions (1 injection per 15 min) through a septum (the nitrogen-flow in the Schlenk line was stopped before injection). The reaction was stopped by cooling the reaction vessel down to 90 C. The reaction mixture was left to stir for one hour at nitrogen flow. Then 15 ml of chloroform were added and the nanocrystals were precipitated by addition of methanol and centrifugation. The precipitate was re-dissolved in chloroform and the washing procedure was repeated twice. Synthesis of Fe 3 O 4 nanoparticles The hot injection technique was also used to produce Fe 3 O 4 nanoparticles. The synthesis was performed under inert nitrogen atmosphere using a Schlenk technique. Typically 7 g of hexadecylamine, 3 ml of diphenylether and 77 mg of trimethylamin-n-oxid were degassed at 75 C. The reaction mixture was heated to 170 C and 0.13 ml of ironpentacarbonyl were injected. Nanparticles growth was carried out at 290 C for 90 min. After cooling to 75 C 15 ml of chloroform were added. The particles were purified by precipitation using 2-propanol as a nonsolvent, centrifugation and re-dissolution in a toluene. This cleaning procedure was repeated three times and the final nanoparticle solution was filtrated through 0.2 µm syringe filter. Synthesis of CoPt 3 nanoparticles CoPt 3 nanoparticles were synthesised according to published procedure with small changes in the amounts of used chemicals. [3] The synthesis was carried out using standard Schlenk line technique under dry nitrogen. Platinum(II)-acetylacetonate ( g) 1,2- hexadecandiol (0.26 g) and 1-adamantancarboxylic acid (0.496 g) were dissolved in a mixture of coordinating solvents (4 ml of diphenylether and 8.0 g hexadecylamine) at 65 o C in a threeneck flask. To produce CoPt 3 nanocrystals, the reaction mixture was heated to the 175 o C and the cobalt stock solution was injected into the flask under vigorous stirring. The cobalt stock

5 solution was freshly prepared before the synthesis by dissolving g of cobalt carbonyl (Co(CO) 8 ) in 1.6 ml of 1,2-dichlorobenzene at room temperature under airless conditions. The reaction mixture was heated one hour at the injection temperature, and two hours at 230 o C in order to improve the crystallinity of the nanoparticles. Afterwards the reaction mixture was cooled to 60 o C and 10 ml of chloroform were added to the crude solution of CoPt 3 nanoparticles. The particles were purified by precipitation using 2-propanol as a nonsolvent, centrifugation and re-dissolution of the precipitate in chloroform. This cleaning procedure was repeated three times and the final nanoparticle solution was filtrated through 0.2 µm syringe filter. References: [1] I. Mekis, D. V. Talapin, A. Kornowski, M. Haase, H. Weller, J. Phys. Chem. B 2003, 107, [2] D. V. Talapin, I. Mekis, S. Götzinger, A. Kornowski, O. Benson, H. Weller, J. Phys. Chem. B 2004, 108, [3] E. V. Shevchenko, D.V.Talapin, A. L. Rogach, A. Kornowski, M. Hasse, H. Weller, J. Am. Chem. Soc. 2002, 124,