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Targeting drugs to the central nervous system (CNS) is challenging due to the presence of the blood–brain barrier (BBB). The cutting edge in nanotechnology generates optimism to overcome the growing challenges in biomedical sciences through the effective engineering of nanogels. The primary objective of the present report was to develop and characterize a biocompatible natural chitosan (CS)-based NG that can be tracked thanks to the tricarbocyanine (CNN) fluorescent probe addition on the biopolymer backbone. FTIR shed light on the chemical groups involved in the CS and CNN interactions and between CNN-CS and tripolyphosphate, the cross-linking agent. Both in vitro and in vivo experiments were carried out to determine if CS-NGs can be utilized as therapeutic delivery vehicles directed towards the brain. An ionic gelation method was chosen to generate cationic CNN-CS-NG. DLS and TEM confirmed that these entities' sizes fell into the nanoscale. CNN-CS-NG was found to be non-cytotoxic, as determined in the SH-SY5Y neuroblastoma cell line through biocompatibility assays. After cellular internalization, the occurrence of an endo-lysosomal escape (a crucial event for an efficient drug delivery) of CNN-CS-NG was detected. Furthermore, CNN-CS-NG administered intraperitoneally to female CF-1 mice were detected in different brain regions after 2 h of administration, using fluorescence microscopy. To conclude, the obtained findings in the present report can be useful in the field of neuro-nanomedicine when designing drug vehicles with the purpose of delivering drugs to the CNS. [ABSTRACT FROM AUTHOR]

Sub Antarctic soft coral Alcyonium paessleri provided extracts for fifteen illudalane sesquiterpenoids, alcyopterosins A-O and their structures were determined using spectroscopic techniques. Eight of these compounds are the first natural nitrate esters.

Research has been conducted on the homodimeric hemoglobin ferric form. The use of optical absorption and resonance Raman spectroscopy in investigating the heme pocket mutants is described.

The decreased overall polarity of the heme pocket in the homodimeric hemoglobin from the mollusk Scapharca inaequivalvis induces a substantial increase in the stability of both the ferrous and the ferric cyanide complexes. Hence, it was possible to characterize for the first time the equilibrium and kinetic behavior of cyanide binding to a ferrous hemoglobin and to compare them with those of the ferric cyanide complex.

Single-molecule spectroscopy is used for studying water-soluble perylene dicarboximide fluorophores (PDI), which are immobilized in aqueous buffer by attaching the fluorophore to DNA. The studies have evaluated how the fluorescence control of PDIs is used for superresolution 'Blink-Microscopy' in aqueous or organic media and for single-molecule spectroscopy.

Two fluoro-substituted versions, F2FIAsH and F4FIAsH, displaying significant improvements in important properties over the original fluorescein derivative FIAsH are presented. The two compounds have formed an excellent FRET pair with a large critical distance and their properties might facilitate improved structural and dynamic studies of proteins in living cells.

We report the synthesis of a near-infrared (NIR) fluorescent pH probe with a remarkable Stokes shift (∼135 nm) based on a tricarbocyanine (Cy-PIP). The fluorescent molecule was anchored to SiO2 nanoparticles (Cy-PIP@SiO2) and is capable of monitoring pH changes within the physiological range (pH 6–8). The Cy-PIP@SiO2 nanoparticles were successfully internalized by HeLa cells as shown by fluorescence confocal microscopy, while flow cytometry revealed pH fluctuations during the endocytic pathway. [ABSTRACT FROM AUTHOR]

The PhoP/PhoQ two-component system plays an essential role regulating numerous virulence phenotypes in Salmonella enterica. Previous work showed that PhoQ, the sensor protein, switches between the kinase- and the phosphatase-dominant state in response to environmental Mg2+ availability. This switch defines the PhoP phosphorylation status and, as a result, the transcriptional activity of this regulator. In this work, using the FlAsH labelling technique, we examine PhoP cytolocalization in response to extracellular Mg2+ limitation in vitro and to the Salmonella-containing vacuole (SCV) environment in macrophage cells. We demonstrate that in these PhoP/PhoQ-inducing environments PhoP displays preferential localization to one cell pole, while being homogeneously distributed in the bacterial cytoplasm in repressing conditions. Polar localization is lost in the absence of PhoQ or when a non-phosphorylatable PhoPD52A mutant is expressed. However, when PhoP transcriptional activation is achieved in a Mg2+- and PhoQ-independent manner, PhoP regains asymmetric polar localization. In addition, we show that, in the analysed conditions, PhoQ cellular distribution does not parallel PhoP location pattern. These findings reveal that PhoP cellular location is dynamic and conditioned by its environmentally defined transcriptional status, showing a new insight in the PhoP/PhoQ system mechanism. [ABSTRACT FROM AUTHOR]

This paper reports some physico-chemical and functional properties of two of the isolated hemoglobin components from trout (Salmo irideus) blood (Hb trout I and Hb trout IV). Both hemoglobins in the oxygenated state are tetrameric at pH between 7 and 7.8 and protein concentration above &assymp; 0.1 mg/ml. The tetramer is extremely stable towards dissociation into subunits and the stability constants, estimated by differential gel filtration, are between 10 and 50 times larger than that of human hemoglobin in phosphate buffer. A very small degree of dissociation is also suggested by the very small extent of hybrid formation even in concentrated KI or triethanolamine. The dichroic properties of both Hb trout I and Hb trout IV show distinct features in the wavelength region between 300 and 200 nm. Hb trout IV resembles human hemoglobin in the shape of the CO spectrum and in the values of the reduced ellipticity (θ); furthermore upon deoxygenation the value of θ at 222 nm becomes more negative by about 50%. On the ether hand Hb trout I shows a different circular dichroism spectrum and in particular the ellipticity at 222 nm is lower than that of Hb trout IV. Moreover the spectrum is insensitive to the presence of heme ligands. Hb trout IV binds human haptoglobin (Hp) as shown by quenching of the fluorescence of the tryptophanyl residues of Hp upon addition of hemoglobin. The apparent stoichiometry of complex formation corresponds to two Hb tetramers per Hp molecule (while for human hemoglobin the stoichiometry corresponds to &assymp; one tetramer per Hp). A clear cut effect of Hp binding is observed on the kinetics of O2 and especially CO combination as studied by flash photolysis. The effect of several third components on the O2 equilibrium of both Hb trout I and IV has been investigated. In general the effect of adding ions or other molecules to a solution of lib trout I is very minor. On the other hand Hb trout IV is more susceptible to changes in solvent composition. Of particular importance is the action of ATP, the physiological organic phosphate, which is without effect on Hb trout I, while it has a clear effect on Hb trout IV. The addition of ATP shifts the Root effect, the characteristic property of Hb trout IV, to higher pH values, thereby acting as one of the allosteric effectors. [ABSTRACT FROM AUTHOR]

The binding of reduced cofactor (NADH) to glutamate dehydrogenase has been studied by gel filtration, equilibrimn dialysis and fluorescence enhancement. The number of binding sites significantly exceeds 1 per polypeptide chain (1.3 per chain of molecular weight 56 000), the saturation curve gives indications of slight positive interactions. The presence of GTP, glutamate and ADP, apart from increasing the affinity of NADH for glutamate dehydrogenase, appears to affect both the number of binding sites and the cooperativity of the binding. [ABSTRACT FROM AUTHOR]