1335 J. Indian Chem. Soc., Vol. 94, December 2017, pp. 1335-1348 Effective delivery of doxorubicin using biologically synthesized gold nanoparticles for cancer therapy † Ayan Kumar Barui a , Sourav Das a , Preetika Soanpet a , Bojja Sreedhar b and Chitta Ranjan Patra a# * a Chemical Biology Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, India E-mail : crpatra@iict.res.in, patra.chitta@gmail.com b Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad-500 007, India # Academy of Scientific and Innovative Research (AcSIR), Training and Development Complex, CSIR Campus, CSIR Road, Taramani, Chennai-600 113, India Manuscript received 27 October 2017, accepted 01 November 2017 Abstract : We synthesized gold nanoparticles (AuHS) by a single step reduction of chloroauric acid solution using aqueous leaf extract of Hibiscus sabdariffa (HS) plant through an environmental-friendly bio-green ap- proach. The as-synthesized AuHS nanoparticles were thoroughly characterized by several analytical techniques including UV-Visible spectroscopy, DLS, XRD, TEM, XPS and ICP-OES. Cell viability assay revealed that the nanoparticles are highly biocompatible to various normal cells (EA.hy926 and CHO) as well as cancer cells (HCT-15, HeLa, PC3 and A549). The chick embryonic angiogenesis (CEA) assay also supported the biocompatible nature of AuHS nanoparticles. The nanoparticles were found to be stable in different physio- logical buffer and other solutions, indicating the feasibility of their biological applications. Considering the biocompatibility of AuHS nanoparticles, FDA approved anti-cancer drug doxorubicin (DOX) was conjugated with the nanoparticles to design a drug delivery system (DDS : AuHS-DOX). The administration of AuHS- DOX to different cancer cells (HCT-15, HeLa and PC3) manifested more inhibition of cell proliferation com- pared to pristine DOX, suggesting the therapeutic efficacy of the DDS. The better therapeutic response of the DDS could be attributed to the enhanced cellular uptake of DOX present in AuHS-DOX compared to free DOX as observed by confocal microscopy. We strongly believe that the biocompatible AuHS nanoparticles could be employed as an effective delivery vehicle for cancer therapy through nanomedicine approach in im- minent future. Keywords : Gold nanoparticles, biosynthesis, green chemistry approach, drug delivery system, nanomedicine, cancer therapy. Introduction Nanotechnology, one of the emerging technolo- gies of modern world, exhibits its enormous potential for various biomedical applications including diagno- sis and therapy of different diseases such as cancer, cardiovascular diseases, neurodegenerative diseases, diabetes, microbial infection etc. 1–8 . Since past de- cades, among various nanomaterials, gold nano- particles got more attention to the researchers for their diverse applications in varied field including sensor, catalysis, electronics as well as disease diagnosis and therapeutics due to several advantages e.g. (i) simple synthesis method, (ii) easier characterization because of their surface plasmon resonance (SPR) band, (iii) † Dr. D. S. Bhakuni Award Lecture (2016).