Colloids and Surfaces B: Biointerfaces 143 (2016) 131–138 Contents lists available at ScienceDirect Colloids and Surfaces B: Biointerfaces journal homepage: www.elsevier.com/locate/colsurfb Intracellular interactions of electrostatically mediated layer-by-layer assembled polyelectrolytes based sorafenib nanoparticles in oral cancer cells Radhika Poojari ∗ , Sudarshan Kini, Rohit Srivastava, Dulal Panda ∗ Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India a r t i c l e i n f o Article history: Received 16 October 2015 Received in revised form 7 March 2016 Accepted 8 March 2016 Available online 10 March 2016 Keywords: Sorafenib Kinase inhibitor Layer-by-layer assembled polyelectrolytes Calcium carbonate nanoparticles Oral cancer cells a b s t r a c t In this paper, we report the preparation of LbL-nanoSraf (100–300 nm) comprising of layer-by-layer (LbL) assembled polyelectrolytes dextran-sulfate/poly-l-arginine, with a multikinase inhibitor sorafenib (Sraf) encapsulated calcium carbonate (CaCO 3 ) nanoparticles for oral cancer therapy in vitro. The zeta potential of LbL-nanoSraf exhibited a negative charge of the polyanionic dextran sulfate, which alternated with a positive charge of polycationic poly-l-arginine indicating a successful LbL assembly of the two polyelec- trolyte bilayers on the CaCO 3 nanoparticles. The LbL-nanoSraf exhibited an encapsulation efficiency of 61 ± 4%. The LbL-nanoSraf was characterized using field-emission gun scanning electron microscopy, X- ray powder diffraction, atomic force microscopy and confocal laser scanning microscopy. Confocal laser scanning microscopy, flow cytometry and transmission electron microscopic investigations showed the internalization of LbL-nanoSraf in human oral cancer (KB) cells. The LbL-nanoSraf exhibited more potent antiproliferative, apoptotic and antimigratory activities in KB cells than the free drug Sraf. The findings could promote the application of nano-sized LbL assembled polyelectrolytes for the delivery of Raf-kinase inhibitors and provide mechanistic insights for oral cancer therapy. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Oral cancer has emerged as one of the deadliest cancers and the incidence of oral cancer is increasing with an alarming rate [1,2]. The major causes of oral cancer include the consumption of alcohol and tobacco and exposure to human papillomavirus (HPV). Despite continued advancement in diagnostic techniques and treatment modalities such as surgery and chemoradiother- apy, the treatment of oral cancer is still a major challenge [1–3]. Therefore, a new therapeutic modality for oral cancer remains a priority. Small molecule inhibitors of tyrosine kinases (TKIs) such as sorafenib represent an attractive therapeutic strategy for can- cer treatment [4]. Sorafenib inhibits tumor cell proliferation, tumor angiogenesis, metastasis and invasion [4,5]. Sorafenib has been shown to inhibit tyrosine kinases, RAF/MEK/ERK pathways and c- Raf-1 and B-Raf proteins [4,5]. The therapeutic effects of sorafenib have been validated in a number of preclinical and clinical studies including advanced hepatocellular carcinoma, renal cancer, breast ∗ Corresponding authors. E-mail addresses: drradhikapoojari@gmail.com (R. Poojari), panda@iitb.ac.in (D. Panda). cancer, colon cancer, melanoma, non-small cell lung cancer and drug resistant cancers [6,7]. Recently, the combination of sorafenib and radiation has been found to produce synergistic effects in oral carcinoma [8,9]. However, poor oral bioavailability, low solubil- ity, non-specific targets, rapid metabolism and clearance, repeated high dose medication, adverse side-effects such as gastrointesti- nal bleeding, hypertension, hepatotoxicity, dermatological toxicity (hand-foot syndrome), dysgeusia and diarrhoea severely limit the therapeutic effectiveness of sorafenib in cancer patients [10,11]. However, an efficient delivery system can circumvent the side effects of sorafenib, which in turn will increase the efficacy of sorafenib for oral cancer therapy. Several types of delivery systems have been designed to increase the oral bioavailability and targeting ability of sorafenib [12–18]. Sorafenib nanoformulations [12], solid lipid nanoparticles [13], folate-polymeric polyethylene glycol-block- poly(-caprolactone) micelles with superparamagnetic iron oxide [14], transferrin-albumin nanoparticles [15], peptide arginine- glycine-aspartic acid (RGD)-porous silicon nanoparticles [16], multiblock polymer poly(lactic acid)-poly(ethylene glycol)-poly(l- lysine)-diethylenetriamine pentaacetic acid, the pH-sensitive material poly(l-histidine)-poly(ethylene glycol)-biotin [17], and lipid coated nanodiamonds [18] have been reported so far using http://dx.doi.org/10.1016/j.colsurfb.2016.03.024 0927-7765/© 2016 Elsevier B.V. All rights reserved.