Accumulation Of Nanomaterials Research Articles

Interplay between gold nanoparticle biosynthesis and metabolic activity of cyanobacteriumSynechocystis sp. PCC 6803

Many microorganisms have long been known to be able to synthesize nanoparticles eitherin extracellular media or inside cells but the biochemical mechanisms involved inbiomineralization are still poorly understood. In this paper we report the intracellularsynthesis of gold nanoparticles (GNPs) by the cyanobacterium Synechocystis sp. PCC 6803exposed to an aqueous solution of chloroauric acid. We assess the interplay between thebiomineralization process and the metabolic activities (i.e. photosynthesis and respiration)of cyanobacteria cells by correlating the GNP synthesis yield with the amount ofrespiratory and photosynthetic oxygen exchange. The biogenic GNPs are compared interms of their internalization and biological effects to GNPs synthesized by a standardcitrate reduction procedure (cGNPs). The TEM analysis, in conjunction with spectroscopicmeasurements (i.e. surface plasmon resonance, fluorescence quenching and surface-enhancedRaman scattering, SERS), reveals the localization of biogenic GNPs at the level ofintracytoplasmic membranes whereas the pre-formed cGNPs are located at thelevel of external cellular membrane. Our findings have implications for betterunderstanding the process of biomineralization and assessing the potential risksassociated with the accumulation of nanomaterials by various biological systems.

4-N-pyridin-2-yl-benzamide nanotubes compatible with mouse stem cell and oral delivery inDrosophila

p-aminobenzoic acid (PABA), a structural moiety of many commercial drugs, isself-assembled with linker alkyl side chains to form tubular nanostructures. The tubesexhibited fluorescence either intrinsic or from fluorescent molecules embedded in the wallduring self-assembly. Uptake and inter-cellular delivery of the conjugated nanotubes inhuman cancer cells and in mouse embryonic stem cells were demonstrated by fluorescenceimaging and flow cytometry. Biocompatibility, cytotoxicity and clearance were monitoredboth ex vivo in mouse multipotent embryonic stem cells and in vivo in adult Drosophila.Accumulation of nanotubes had no adverse effects and abnormalities on stemcell morphology and proliferation rate. A distinct distribution of two separatenanotubes in various internal organs of Drosophila interprets that accumulation ofnanomaterials might be interdependent on the side chain modifications and physiologicalsettings of cell or tissue types. Unlike carbon nanomaterials, exposure of PABAnanotubes does not produce any hazards including locomotion defects and mortality ofadult flies. Despite differential uptake and clearance from multiple live tissues,the use of self-assembled nanotubes can add new dimensions and scope to thedevelopment of dual-purpose oral carriers for the fulfilment of many biological promises.