The study was conducted at the Laboratory Animals Center of Chinese PLA General Hospital (301 Hospital), Beijing, under a protocol that was reviewed and approved by the ethics committee of the hospital. Seven adult male rhesus macaques (six treated, one control) ranging from 3 to 4 years in age and from 4.8 to 7.7 kg in mass were purchased from the Institute of Beijing XIEERXIN Biology Resource. Animals were individually housed in stainless steel cages (20-22°C, 40-60% relative humidity, 12/12 hours light/dark cycle, 15 air changes per hour) and fed a commercial monkey diet. Water was available ad libitum. Research staff inspected the monkeys three times each day. Quantum dot (10 mg ml-1) dispersions in 0.9% sodium chloride were filter-sterilized before injection. Animals were anaesthetized by subcutaneous injection of 50-75 mg ketamine (0.1 g 2 ml-1). Encapsulated quantum dots (25 mg kg-1) were administrated to six monkeys by intravenous drip. Urine and fasting blood samples were collected weekly. Body mass, temperature, appearance and exploratory behaviour were recorded at the same time. Before quantum dot injection, three monkeys were subject to urine and blood testing as the normal control. Venous blood samples (7-8 ml) were collected in evacuated tubes containing EDTA, sodium citrate anticoagulants and non-anticoagulant agents. The blood analysis (haematology, coagulation and chemistry) was carried out on Sysmex XS-800i, Roche STA-R Evolution and Cobas 6000-C501 units, respectively. Urine (3-5 ml) was taken for urinalysis on a Roche URISYS 2400 and Sysmex UF-lOOi.
Monkeys were killed by ketamine anaesthetic and 10% KC1. Heart, liver, spleen, lungs, kidneys, colon (section 10 cm in length), muscle (5 cm x 7 cm), lymph nodes and brain were collected, weighed and fixed with 10% buffered formalin. Bone marrow (from the femur) was prepared by smearing on glass slides and staining with Wright's stain. Haematoxylin and eosin-stained histological sections of the fixed organs were observed with an Olympus BX60 microscope at x40 magnification. Tissue sections were examined by two independent clinical pathologists who were not told what treatment the monkeys had undergone or which samples were from the control monkey.
Inductively Coupled Plasma Mass Spectrometry (ICP-MS) Analysis and Fluorescence Imaging
Tissue samples for ICP-MS analysis and fluorescence imaging were collected from three animals and kept at -20°C. For ICP-MS, three fragments were sampled as a set from each organ of interest. Organs and sample sets were weighed before being frozen, with each set weighing ~1 g. Standard cryosectioning was performed for fluorescence imaging of the organs. Elemental concentrations were determined using a quadrupole-based ICP-MS system (Elan DRC-II, PerkinElmer SCIEX Instruments; resolution, ~0.7-0.9 AMU). Samples were digested with HN03 and HC1 (HN03:HC1 ratio of 10:1) at 60°C for analysis.
This work was supported by The John R. Oishei Foundation, Air Force Office of Scientific Research (grant no. FA95500610398), the Singapore Ministry of Education (Grants Tier 2 МОЕ20Ю- T2-2-010 (M4020020.040 ARC2/11) and Tier 1 M4010360.040 RG29/10), Nanyang Technological University (start-up grant no. M4080141.040), the Beijing Natural Science Foundation (no. 7092097) and the National Natural Science Foundation of China
(no. 21071150). The authors thank A. Maitra of Johns Hopkins University for helpful discussions.
K.T.Y. and L.Y. designed the research. K.T.Y, L.Y., R.H., L.L., J.Z.,
I.R.W.C.L., J.L., K.W., J.L., Y.L. and Y.H. performed the research. L.Y.,
K.T.Y., L.L., I.R., R.H., J.Z., H.C., W.C.L., J.L., K.W., J.L., Y.L., Y.H., X.Z., M.T.S. and RN.R analysed the data. K.T.Y., L.Y., I.R., M.T.S. and P.N.R co-wrote the paper.