Arsenic trioxide loaded biocompatible PHB-PVA. 1PHB-PVA, poly hydroxy butyrate-poly vinyl alcohol copolymer.1 nanoparticles (<100. nm in size) with folate functionalized surface were synthesized using poly-[(R)-3-hydroxybutyric acid] (PHB) produced by Bacillus firmus NII 0830. Folate functionalization was carried using dicyclohexyl carbodiimide (DCC) as a catalyst and 10-bromodecanol as a linker to conjugate glutamic acid terminal of folate with the hydroxylate groups present on the surface of PHBA-PVA. 2PHBA-PVA, arsenic trioxide loaded poly hydroxyl butyrate-poly vinyl alcohol.2 nanotrojans. The effect of fabrication parameters on shape, size distribution and PDI of the PHB nanoparticles were also investigated. It was observed that increase in sonication time and polyvinyl alcohol (PVA) concentration greatly reduced the size of nanoparticles. The drug release studies on arsenic trioxide incorporated PHB-PVA nanoparticles were conducted at physiological pH and temperature. FOL-PHBA-PVA. 3FOL-PHBA-PVA, folate functionalized PHBA-PVA nanoparticles; PDI, polydispersity index.3 nanoparticles showed greater extent of cytotoxicity towards murine fibrosarcoma L929 cells than PHBA-PVA nanoparticles alone without conjugated folate, indicating the significance of folate as ligand for specific targeting of FR+ cancer cells. © 2013 Elsevier Ltd.