Two-Step Hydrothermal Synthesis of Bifunctional Hematite– Silver Heterodimer Nanoparticles for Potential Antibacterial and Anticancer Applications VU THI TRANG, 1,2 LE THI TAM, 1,5 VU NGOC PHAN, 1 NGUYEN VAN QUY, 3 TRAN QUANG HUY, 4 and ANH-TUAN LE 1,6,7 1.—Department of Nanoscience and Nanotechnology, Advanced Institute for Science and Tech- nology (AIST), Hanoi University of Science and Technology (HUST), No. 1, Dai Co Viet Street, Hai Ba Trung District, Hanoi 10000, Vietnam. 2.—Military Medical University, No. 160, Phung Hung Street, Phuc La Ward, Hadong District, Hanoi 10000, Vietnam. 3.—International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, Hanoi 10000, Vietnam. 4.—National Institute of Hygiene and Epidemiology (NIHE), No. 1-Yersin Street, Hai Ba Trung District, Hanoi 10000, Vietnam. 5.—e-mail: tam.lethi@hust.edu.vn. 6.—e-mail: tuan.hast@gmail.com. 7.—e-mail: tuan.leanh1@hust.edu.vn In recent years, the development of composite nanostructures containing no- ble metal and magnetic nanocrystals has attracted much interest because they offer a promising avenue for multifunctional applications in nanomedicine and pharmacotherapy. In this work, we present a facile two-step hydrothermal approach for the synthesis of bifunctional heterodimer nanoparticles (HDNPs) composed of hematite nanocubes (a-Fe 2 O 3 NCs) and silver nanoparticles (Ag- NPs). The formation and magnetic property of a-Fe 2 O 3 -Ag HDNPs was ana- lyzed by transmission electron microscopy, x-ray diffraction and vibrating sample magnetometer. Interestingly, the hydrothermal-synthesized a-Fe 2 O 3 - Ag HDNPs were found to display significant antibacterial activity against three types of infectious bacteria. The cytotoxicity of a-Fe 2 O 3 -Ag nanocom- posite against lung cancer A549 cell line was investigated and compared with that of pure a-Fe 2 O 3 NCs and Ag-NPs. The obtained results reveal that the a- Fe 2 O 3 -Ag nanocomposite exhibited higher anticancer performance than that of pure Ag-NPs, whereas pure a-Fe 2 O 3 NCs were not cytotoxic to the tested cells. The inhibitory concentration (IC 50 ) of the a-Fe 2 O 3 -Ag nanocomposite was found at 20.94 lg/mL. With the aforementioned properties, a-Fe 2 O 3 -Ag HDNPs showed a high potential as a multifunctional material for advanced biomedicine and nanotherapy applications. Key words: Fe 2 O 3 -Ag magnetic nanocomposites, antibacterial, anticancer, hydrothermal synthesis INTRODUCTION Nowadays, functional nanoparticles (NPs) have been increasingly used for many biomedical appli- cations such as targeted drug delivery, prevention and diagnosis of infectious diseases, bioimaging and cancer therapy. 1,2 Among the existing functional NPs, silver nanoparticles (Ag-NPs) are interesting nanomaterials that have attracted the most interest because of their excellent optical and antimicrobial properties. 3 Due to high surface area and large surface energy, Ag-NPs can be effectively used for photocatalysis and absorption applications. 4 Also, surface plasmon resonances (SPR) in Ag-NPs, which come from resonant oscillation of free conduction electrons at the interface of the NPs, were found to result in higher optical absorption and scattering efficiency. 3,4 This SPR property has become an important transducer for advanced bio/chemo (Received September 30, 2016; accepted December 9, 2016) Journal of ELECTRONIC MATERIALS DOI: 10.1007/s11664-016-5227-5 Ó 2016 The Minerals, Metals & Materials Society