Picomolar concentrations

R.M. Pemberton, T.T. Mottram, and J.P. Hart, Development of a screen-printed carbon electrochemical immunosensor for picomolar concentrations of estradiol in human serum extracts. J. Biochem. Biophys. Methods 63, 201-212 (2005). 

Petit [563] has described a method for the determination of tellurium in seawater at picomolar concentrations. Tellurium (VI) was reduced to tellurium (IV) by boiling in 3 M hydrochloric acid. After preconcentration by coprecipitation with magnesium hydroxide, tellurium was reduced to the hydride by sodium borohydrate at 300 °C for 120 seconds, then 257 °C for 12 seconds. The hydride was then measured by atomic absorption spectroscopy. Recovery was 90 - 95% and the detection limit was 0.5 pmol/1. 

They are very potent regulatory molecules, inducing their characteristic effects at nanomolar to picomolar concentrations. 

In addition to directly eliciting cell chemotaxis and free-radical production, PAF can also induce the release of various inflammatory cytokines, amongst which tumour necrosis factor (TNF) is of particular importance [ 312 ]. We have recently shown that PAF stimulates TNF production from peripheral blood derived monocytes and at picomolar concentrations amplifies lipopoly-saccharide (LPS)-induced TNF production, effects inhibited by various PAF antagonists [313]. PAF also acts synergistically with interferon-y (IFN-y) to increase the monocyte cytotoxicity. Furthermore, PAF can modulate the production of both interleukin 1 and interleukin 2 (IL-1, IL-2) from rat monocytes and lymphocytes, respectively [222, 223], cytokines which in turn elicit the release of other mediators and growth factors. 

Wygladacz K, Bakker E (2007) Fluorescent microsphere fiber optic microsensor array for direct iodide detection at low picomolar concentrations. Analyst 132 268-272... 

The effect with which PPT modulate the response of platelets is also pertinent to vascular disease, in particular, thrombosis. Resting platelets inhibit the respiratory burst of neutrophils whereas thrombin-activated platelets increase the respiratory burst. Quercetin and resveratrol at picomolar concentrations attenuate this response by preserving endothelial CD39/ATP-dase," " and on present evidence (see above) such concentrations might be achieved locally following deglucuronidation at a site of inflammation. 

Lagrange, H., Jay-Allgmand, C., and Lapeyrie, F., Rutin, the phenolglycoside from eucalyptus root exudates, stimulates Pisolithus hyphal growth at picomolar concentrations, New PhytoL, 149, 349, 2001. 

E. P. Achterberg, P. N. Sedwick, S. Ussher, and P. J. Worsfold, Real-Time Monitoring of Picomolar Concentrations of Iron(lI) in Marine Waters Using Automated Flow Injection-Chemiluminescence Instrumentation, Environ. Sci. TechnoL 2002,36, 4600. 

Used to introduce chromophores into carboxylic acids, without the need for a base catalyst, and under mild conditions picomolar concentrations are rendered detectable Reference 33... 

Muhlradt, P.F., Kiess, M., Meyer, H., Sussmuth, R., and Jung, G. (1997) Isolation, structure elucidation, and synthesis of a macrophage stimulatory lipopeptide from Mycoplasma fermentans acting at picomolar concentration../. Exp. Med. 185(11), 1951-1958. 

Gioannini, T.L., Teghanemt, A., Zhang, D., Coussens, N.P., Dockstader, W., Ramaswamy, S., Weiss, J.P. Isolation of an endotoxin-MD-2 complex that produces Toll-like receptor 4-dependent cell activation at picomolar concentrations. Proc Natl Acad Sci USA 101 (2004) 4186-4191. 

A very different detection approach was used [40] based on the electro-catalytic oxidation of sugars and amines at a copper electrode surface. The ssDNA and dsDNA were detected in the picomolar concentration range. The electrochemical signal due to dsDNA was higher than due to ssDNA owing to the larger number of easily accessible sugars on the outer perimeter of dsDNA double helix compared to those on a ssDNA of the same size, in contrast to most electrochemical studies based on the electroactivity of the bases. 

Until recently, it was difficult to approach the question of how zinc concentrations are sensed within cells. Zinc proteins are abundant, and total zinc concentrations are quite high within cells (0.2 mM), even though most zinc is tightly bound to proteins and is therefore unlikely to be sensed by cytosolic regulatory proteins. The idea that cytosolic regulatory proteins sample a pool of free or loosely bound zinc at micromolar to picomolar concentrations has recently been discarded in favor of a model in which it is postulated that there is virtually... 

Biosensor SERS possesses many desirable characteristics as a tool for biosensing with high specificity, attomole to high zeptomole mass sensitivity, and to picomolar concentration sensitivity. Recently, SERS has been used in the quantitative detection and analysis of bio-related molecules [2]. 

Analytical Difficulties Although we can make many chemical equilibrium models that predict the existence of complexes in natural waters, analytically one encounters difficulties in identifying unequivocally the various solute species and in distinguishing between dissolved and particulate concentrations. The analytical task is rendered veiy difficult because the individual chemical species are often present at nano- and picomolar concentrations. The ion-selective electrode (ISE), if it were sufficiently sensitive, would permit the measurement of free metal-ion activity. 

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