Optical frequency comb based system for photonic refractive index sensor interrogation.

In this contribution, we demonstrate how an optical frequency comb can be used to enhance the functionality of an integrated photonic biosensor platform. We show that if an optical frequency comb is used to sample the spectral response of a Mach-Zehnder interferometer and if the line spacing is arranged to sample the periodic response at 120° intervals, then it is possible to combine these samples into a single measurement of the interferometer phase. This phase measurement approach is accurate, independent of the bias of the interferometer and robust against intensity fluctuations that are common to each of the comb lines. We demonstrate this approach with a simple silicon photonic interferometric refractive index sensor and show that the benefits of our approach can be obtained without degrading the lower limit of detection of 3.70×10-7 RIU.

Cannabinergic ligands.

The understanding of the pharmacology surrounding the cannabinergic system has seen many advances since the discovery of the CB1 receptor in the mammalian brain and the CB2 receptor in the periphery. Among these advances is the discovery of the endogenous ligands arachidonoylethanolamide (anandamide) and 2-arachidonoylglycerol amide (2-AG), which are selective agonists for the CB1 and CB2 receptors, respectively. These endogenous neuromodulators involved in the cannabinergic system are thought to be produced on demand and are metabolized by the enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAG lipase). Recently, we characterized a reuptake system that facilitates the transport of anandamide across the cell membrane and subsequently developed selective inhibitors of this transport, which have been found to have therapeutic potential as analgesic and peripheral vasodilators. The cannabinergic proteins currently being explored, which include the CB1 and CB2 receptors, FAAH and the anandamide transporter, are excellent targets for the development of therapeutically useful drugs for a range of conditions including pain, loss of appetite, immunosuppression, peripheral vascular disease and motor disorders. As cannabinoid research has progressed, various potent and selective cannabimimetic ligands, targeting these four cannabinoid proteins, have been designed and synthesized. Many of these ligands serve as important molecular probes, providing structural information regarding the binding sites of the cannabinergic proteins, as well as pharmacological tools, which have been playing pivotal roles in research aimed at understanding the biochemical and physiological aspects of the endocannabinoid system. This review will focus on some of the current cannabinergic ligands and probes and their pharmacological and therapeutic potential.

Enantiomeric resolution of a novel chiral cannabinoid receptor ligand.

The enantiomeric resolution of a racemic novel cannabinoid receptor ligand conformationally restricted at the southern aliphatic chain was accomplished using a ChiralPak AD column. Both enantiomers were tested for their competitive binding to the rat brain CB1, mouse spleen CB2 and human CB2 receptors. The levorotatory isomer showed exceptionally high affinity for the CB1 receptor with a seven-fold selectivity over CB2.