Li et al. Nanoscale Res Lett 2011, 6:29 http://www.nanoscalereslett.com/content/6/1/29 Page 7 of 8 A 80 % / y t ili 60 b a i v l l e fc 40 o e s a rce 20 e D 0 -(DNR) -(PLA+DNR) -(PLA/Au+DNR) -(DNR) -(PLA+DNR) -(PLA/Au+DNR) B 80 % / ity 60 l i b a i v l l ce 40 f o e s a re 20 c e D 0 0.1 0.2 0.4 0.6 0.8 Concentration of DNR/ μmol/L 2.5 5 10 20 40 Concentration of DNR/ μmol/L Figure 5 MTT assay to test the cytotoxicity of DNR in the presence of PLA or PLA/Au nanocomposites for K562 cells (a) and K562/ AO2 cells (b) for 48 h. Error bars, ±SEM. Table 1 The resistant factors and reversal index of leukemia K562 and K562/AO2 cell lines to PLA/Au nanocomposites Groups Control group Experimental (PLA/Au) group IC50/μmol/L K562 0.51 0.25 K562/AO2 35.77 9.72 Resistant factors Reversal index 70.14 38.88 1.8 Conclusion In summary, in this study we have fabricated the new PLA/Au nanocomposites and explored the promising application of the PLA/Au nanocomposites to efficiently facilitate the uptake of anticancer drug in target cancer cells. Our observations demonstrate that the self-assem- bly and conjugation of anticancer drug DNR on the sur- face of PLA/Au nanocomposites could significantly enhance the drug accumulation into drug-sensitive K562 and drug-resistant leukemia K562/AO2 cells and thus increase the drug’s cytotoxicity. Importantly, the PLA/Au nanocomposites could considerably reverse the multi- drug resistance of K562/AO2 cells and efficiently inhibit the cancer cell proliferation. This raised the possibility to utilize the PLA/Au nanocomposites as a new effective additive agent to overcome the drug resistance and thus as a novel strategy to sensitively track the respective can- cer cells for efficient cancer chemotherapy. Acknowledgements This work is supported by National Natural Science Foundation of China (90713023, 20675014 and 20535010), National Basic Research Program of China (No. 2010CB732404), the Chinese Ministry of Science and Technology (2007AA022007 and 2008DFA51180), the Natural Science Foundation of Jiangsu Province (BK2008149), Visiting Scholar Foundation of Key Laboratory of Biorheological Science and Technology (Chongqing University) and the Graduate Research and Innovation Program of Jiangsu Province (CX10B_083Z). Author details 1State Key Lab of Bioelectronics (Chien-Shiung WU Laboratory), Southeast University, 210096, Nanjing, China. 2Department of Hematology, Zhongda Hospital, Southeast University, 210096, Nanjing, China. Received: 3 July 2010 Accepted: 14 August 2010 Published: 14 September 2010 References 1. Alexiou C, Arnold W, Klein RJ, Parak FG, Hulin P, Bergemann C, Erhardt W, Wagenpfeil S, Lubbe AS: Cancer Res 2000, 60:6641-6648. 2. Breuninger LM, Paul S, Gaughan K, Miki T, Chan A, Aaronson SA, Kruh GD: Cancer Res 1995, 55:5342-5347. 3. Litman T, Nielsen D, Skovsgaard T, Zeuthen T, Stein WD: Biochim Biophys Acta 1997, 1361:147-158. 4. Song M, Guo DD, Pan C, Jiang H, Chen C, Zhang RY, Gu ZZ, Wang XM: Nanotechnology 2008, 19:165102. 5. Zhang RY, Wang XM, Wu CH, Song M, Li JY, Lv G, Zhou J, Chen C, Dai YY, Gao F, Fu DG, Li XM, Guan ZQ, Chen BA: Nanotechnology 2006, 17:3622-3626. 6. Wu W, Wieckowski S, Pastorin G, Benincasa M, Klumpp C, Briand JP, Gennaro R, Prato M, Bianco A: Angew Chem Int Edit 2005, 44(39):6358-6362. 7. Peng T, Su J, Cheng SX, Zhuo RX: J Mater Sci Mater M 2007, 18(9):1765-1769. 8. Li JY, Wang XM, Wang CX, Chen BA, Dai YY, Zhang RY, Song M, Lv G, Fu DG: Chem Med Chem 2007, 2(3):374-378. 9. Bianco A, Kostarelos K, Partidos CD, Prato M: Chem Commun 2005, 2:571-577. 10. Schroeder U, Sommerfeld P, Ulrich S, Sabel BA: J Pharm Sci 1998, 87(11):1305-1307. 11. Paciotti GF, Kingston DG, Tamarkin L: Drug Develop Res 2006, 67:47-54. 12. Li JY, Wu CH, Gao F, Zhang RY, Lv G, Fu DG, Chen BA, Wang XM: Bioorg Med Chem Lett 2006, 16(18):4808-4812. 13. Nie X, Leyland A, Matthews A: Surf Coat Tech 2000, 125:407-414. 14. Ishihara T, Mizushima T: Expert Opin Drug Del 2010, 7(5):565-575.