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BackgroundNanoparticle-metal oxide and gold represents a new class of important materials that are increasingly being developed for use in research and health related activities. The biological system being extremely critical requires the fundamental understanding on the influence of inorganic nanoparticles on cellular growth and functions. Our study was aimed to find out the effect of iron oxide (Fe3O4), gold (Au) nanoparticles on cellular growth of Escherichia coli (E. coli) and also try to channelize the obtained result by functionalizing the Au nanoparticle for further biological applications.ResultFe3O4 and Au nanoparticles were prepared and characterized using Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS). Preliminary growth analysis data suggest that the nanoparticles of iron oxide have an inhibitory effect on E. coli in a concentration dependant manner, whereas the gold nanoparticle directly showed no such activity. However the phase contrast microscopic study clearly demonstrated that the effect of both Fe3O4 and Au nanoparticle extended up to the level of cell division which was evident as the abrupt increase in bacterial cell length. The incorporation of gold nanoparticle by bacterial cell was also observed during microscopic analysis based on which glutathione functionalized gold nanoparticle was prepared and used as a vector for plasmid DNA transport within bacterial cell.ConclusionAltogether the study suggests that there is metal nanoparticle-bacteria interaction at the cellular level that can be utilized for beneficial biological application but significantly it also posses potential to produce ecotoxicity, challenging the ecofriendly nature of nanoparticles.

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Dysfunctions in the norepinephric pathway have been speculated in the etiology of attention deficit hyperactivity disorder (ADHD), a common problem for children. Synthesis of norepinephrine from dopamine is catalyzed by the enzyme dopamine beta-hydroxylase and numerous polymorphisms in the DBH gene have been found to exert their direct influence on the enzyme activity independently. In the present study association of ADHD with four genetic polymorphisms, DBH-STR, rs1611115, rs1108580, and rs2519152, was examined in subjects belonging to eastern India. ADHD subjects (n = 111) were recruited following DSM-IV criteria. Peripheral blood samples were collected from nuclear families with ADHD probands. A group of ethnically matched healthy volunteers (n = 130) was also recruited. Genomic DNA was analyzed by PCR amplification followed by restriction digestion and genotyping. Data obtained were subjected to both family-based as well as population-based statistical analyses. Plasma DbetaH activity was measured using a photometric assay and its correlation with the genetic polymorphisms was analyzed using analysis of variance. Case-control analysis revealed no significant differences in allelic frequencies; however, significant paternal over-transmission (P = 0.02) of the rs2519152 'G' allele to ADHD probands was noticed. A haplotype, composed of 12R-C-G-G, also showed biased transmission. Strong correlation was observed between enzyme activity and rs1611115, rs1108580, and rs2519152 (P = 1.51E-6, 0.04, and 0.003, respectively). The present study hints toward the fact that DBH gene polymorphisms have some role in the etiology of ADHD in eastern Indian population and their study could be useful for therapeutic intervention.