Self-Assembly of TbPc2 Single-Molecule Magnets on Surface through Multiple Hydrogen Bonding

The complexation between 2-ureido-4[1H]-pyrimidinone (UPy) and 2,7-diamido-1,8-naphthyridine (NaPy) is used to promote the mild chemisorption of a UPy-functionalized terbium(III) double decker system on a silicon surface. The adopted strategy allows the single-molecule magnet behavior of the system to be maintained unaltered on the surface.

An electrochemiluminescence-supramolecular approach to sarcosine detection for early diagnosis of prostate cancer

Monitoring Prostate Cancer (PCa) biomarkers is an efficient way to diagnosis this disease early, since it improves the therapeutic success rate and suppresses PCa patient mortality: for this reason a powerful analytical technique such as electrochemiluminescence (ECL) is already used for this application, but its widespread usability is still hampered by the high cost of commercial ECL equipment. We describe an innovative approach for the selective and sensitive detection of the PCa biomarker sarcosine, obtained by a synergistic ECL-supramolecular approach, in which the free base form of sarcosine acts as co-reagent in a Ru(bpy)3(2+)-ECL process. We used magnetic micro-beads decorated with a supramolecular tetraphosphonate cavitand (Tiiii) for the selective capture of sarcosine hydrochloride in a complex matrix like urine. Sarcosine determination was then obtained with ECL measurements thanks to the complexation properties of Tiiii, with a protocol involving simple pH changes - to drive the capture-release process of sarcosine from the receptor - and magnetic micro-bead technology. With this approach we were able to measure sarcosine in the μM to mM window, a concentration range that encompasses the diagnostic urinary value of sarcosine in healthy subjects and PCa patients, respectively. These results indicate how this ECL-supramolecular approach is extremely promising for the detection of sarcosine and for PCa diagnosis and monitoring, and for the development of portable and more affordable devices.

Multifunctional magnetic nanoparticles for enhanced intracellular drug transport

New multicomponent biocompatible MNPs are designed as intracellular vectors to in situ load antitumor drugs and transport them inside cells.

Magnetic behaviour of TbPc2 single-molecule magnets chemically grafted on silicon surface

Single-molecule magnets (SMMs) are among the most promising molecular systems for the development of novel molecular electronics based on the spin transport. Going beyond the investigations focused on physisorbed SMMs, in this work the robust grafting of Terbium(III) bis(phthalocyaninato) complexes to silicon surface from a diluted solution is achieved by rational chemical design yielding the formation of a partially oriented monolayer on the conducting substrate. Here, by exploiting the surface sensitivity of X-ray circular magnetic dichroism we evidence an enhancement of the magnetic bistability of this single-molecule magnet, in contrast to the dramatic reduction of the magnetic hysteresis that characterises monolayer deposits evaporated on noble and ferromagnetic metals. Photoelectron spectroscopy investigations and density functional theory analysis suggest a non-innocent role played by the silicon substrate, evidencing the potentiality of this approach for robust integration of bistable magnetic molecules in electronic devices.

In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

Free 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100) and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring-surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm(-1) due to -NH stretches. Finally, XPS results revealed that the different surface-phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

Functionalization of PEGylated Fe3O4 magnetic nanoparticles with tetraphosphonate cavitand for biomedical application

In this contribution, Fe3O4 magnetic nanoparticles (MNPs) have been functionalized with a tetraphosphonate cavitand receptor (Tiiii), capable of complexing N-monomethylated species with high selectivity, and polyethylene glycol (PEG) via click-chemistry. The grafting process is based on MNP pre-functionalization with a bifunctional phosphonic linker, 10-undecynylphosphonic acid, anchored on an iron surface through the phosphonic group. The Tiiii cavitand and the PEG modified with azide moieties have then been bonded to the resulting alkyne-functionalized MNPs through a "click" reaction. Each reaction step has been monitored by using X-ray photoelectron and FTIR spectroscopies. PEG and Tiiii functionalized MNPs have been able to load N-methyl ammonium salts such as the antitumor drug procarbazine hydrochloride and the neurotransmitter epinephrine hydrochloride and release them as free bases. In addition, the introduction of PEG moieties promoted biocompatibility of functionalized MNPs, thus allowing their use in biological environments.

Nitric oxide production by macrophages of dogs vaccinated with killed Leishmania infantum promastigotes

Human visceral leishmaniosis is endemic in Southern Italy, where the dog is the main reservoir of viscerotropic strains of Leishmania infantum. The release of nitric oxide (NO) by interferon (IFN)-gamma-activated macrophages is an important leishmanicidal mechanism in several animal species. In this work NO production, phagocytosis and killing capacity of monocyte-derived dog macrophages were evaluated in vitro before and after administration of a vaccine composed of killed Leishmania infantum promastigotes. Moreover, IFN-gamma content was measured in concanavalin A-activated dog peripheral blood mononuclear cell (PBMC) supernatants employed for macrophage stimulation. Phagocytosis, killing capacity and NO production by canine macrophages increased significantly 1 month after vaccine administration, and the increase also persisted 5 months later. In addition, the amount of IFN-gamma in PBMC supernatants was significantly higher after vaccination. Overall, our results suggest the usefulness of evaluating the in vivo protective role of this promastigote preparation in dogs.

High-performance liquid chromatographic assay of the X-ray contrast agent iopiperidol in plasma and urine of rats and humans

Iopiperidol is a non ionic iodinated compound currently under evaluation as a potential contrast medium with anticoagulant property for radiological examinations. An HPLC method for assaying iopiperidol in plasma and urine of rats and humans is described. The analysis is based on the reversed-phase chromatographic separation of iopiperidol and the internal standard (iopamidol) from the endogenous components of the biological fluids, and their detection by UV absorption at 244 nm. The selectivity of the method was satisfactory. The mean absolute recovery was greater than 80%. The precision and accuracy of the analytical methods were in the range 0.3 to 3.3 and -8.5 to +11%, respectively. The detection limits of iopiperidol in plasma (0.1 ml) and urine (0.25 ml) were 0.2 and 0.4 microg/ml, respectively.

High-performance liquid chromatographic determination of the magnetic resonance imaging contrast agent gadobenate ion in plasma, urine, faeces, bile and tissues

The gadobenate ion is an intravascular paramagnetic contrast agent for magnetic resonance imaging. An HPLC method for assaying gadobenate ion in plasma, urine, faeces, bile and tissue samples is described. The analysis is based on the reversed-phase chromatographic separation of gadobenate ion from the endogenous components of biological matrices and detection by UV absorption at 210 nm. The selectivity of the method was satisfactory. The mean absolute recovery was greater than 95%. The precision and accuracy of the analytical methods were in the range 0.1-6.5% and -12 to +9.3%, respectively. The detection limits in plasma (0.1 ml), urine (0.05 ml), dried faeces (200 mg suspended in 4 ml water), bile (0.5 ml), and dried liver tissue (100 mg suspended in 1 ml water) were, respectively, 0.24, 0.47, 2.6, 0.63 and 2.8 nmol ml(-1) (corresponding to 0.16, 0.31, 1.7, 0.42 and 1.9 microg ml(-1)).

High-performance liquid chromatographic determination of the X-ray imaging contrast agent, iofratol, in plasma and urine

Iofratol is currently under evaluation as a potential X-ray contrast medium for angiography and myelography. An HPLC method for assaying iofratol in rat and human plasma and urine samples is described. The analysis is based on the reversed-phase chromatographic separation of iofratol and the internal standard (iopamidol) from the endogenous components of biological fluids, and detection by UV absorption at 242 nm. The selectivity of the method was satisfactory. The mean absolute recovery was greater than 90%. The precision and accuracy of the analytical methods were in the range 0.8-7.4 and -7.8 to +9.7%, respectively. The detection limits in plasma (0.1 ml) and urine (0.5 ml) were 0.1 and 0.4 microg (iofratol)/ml, respectively. The analyte was stable in the different biological matrices when stored at room temperature (20 degrees C) for at least 1 day, 4 degrees C for 1 month and -20 degrees C for 1 year.

Conditioned taste aversion in rats following intrathecal administration of contrast media

PURPOSE

The occurrence of side-effects such as visceral malaise after intrathecal administration of the non-ionic radiography contrast media iomeprol, iopamidol, and iotrolan was assessed in rats by the conditioned tasted aversion procedure.

METHODS

Reduced preference towards a saccharose solution compared with normal water following intraventricular administration of a contrast medium was used as a measure of the aversive response.

RESULTS

At a dose of 100 mg I/kg none of the tested contrast media induced aversion. At 200 and 300 mg I/kg, both iopamidol and iomeprol induced significant aversive responses with respect to control, although the response of the iomeprol group appeared milder than that of the iopamidol group at a dose of 200 mg I/kg. Iotrolan could be tested only at the lowest dose since the high doses caused excessive mortality.

CONCLUSION

Intrathecally administered iomeprol appeared to be well tolerated in rats at doses higher than those suggested for clinical use.

Preclinical safety assessment of iomeprol for injection as contrast medium for myelography

A series of pharmaco-toxicological investigations were carried out in animals in order to assess the neurotolerance of iomeprol, a new nonionic iodinated contrast medium. After intrathecal administration iomeprol was completely eliminated from the cerebrospinal fluid, rapidly cleared from the plasma and excreted unchanged through the kidneys. When administrated intrathecally, iomeprol did not significantly alter the behavioural functions or the physiological activities of the brain. Unlike other contrast media, iomeprol was devoid of any epileptogenic activity. The acute neurotoxicity of iomeprol was comparable with that of iopamidol, but less than that of iohexol, iotrolan and iodixanol. Iomeprol was well tolerated in both rats and dogs following weekly intrathecal administrations for four weeks of doses up to three times higher than those foreseen for clinical use. High neurotolerance in animals and favourable physico-chemical characteristics make iomeprol particularly suitable as a contrast medium for both myelography and cerebral ventriculography.

Pharmacokinetics and tissue distribution of iomeprol in animals

The pharmacokinetics of iomeprol, a new triiodinated nonionic radiographic contrast agent, has been studied in rats, rabbits and dogs. Following intravenous administration, iomeprol did not bind measurably to plasma proteins and was rapidly excreted in unchanged form, mostly through the kidneys. The compound was rapidly distributed to the plasma and thence to the extracellular spaces. Iomeprol did not accumulate in specific organs or tissues except for those involved in its elimination, i.e. the kidneys and the liver. However, 24 h after administration, less than 1% of the injected dose remained in the tissues. The overall profile was very similar to the published profiles of other radiographic contrast agents used in uroangiography.