pH-Induced conversion of bolaamphiphilic vesicles to reduction-responsive nanogels for enhanced Nile Red and Rose Bengal delivery.

This study details the preparation and investigation of molecular nanogels formed by the self-assembly of bolaamphiphilic dipeptide derivatives containing a reduction-sensitive disulfide unit. The described bolaamphiphiles, featuring amino acid terminal groups, generate cationic vesicles at pH 4, which evolve into gel-like nanoparticles at pH 7. The critical aggregation concentration has been determined, and the nanogels' size and morphology have been characterized through Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Circular Dichroism (CD) spectroscopy reveals substantial molecular reconfigurations accompanying the pH shift. These nanogels enhance the in vitro cellular uptake of the lipophilic dye Nile Red and the ionic photosensitizer Rose Bengal into Human colon adenocarcinoma (HT-29) cells, eliminating the need for organic co-solvents in the former case. Fluorescence measurements with Nile Red as a probe indicate the reduction-sensitive disassembly of the nanogels. In photodynamic therapy (PDT) applications, Rose Bengal-loaded nanogels demonstrate notable improvements, with flow cytometry analysis evidencing increased apoptotic activity in the study with HT-29 cells.

Glutathione-responsive molecular nanoparticles from a dianionic bolaamphiphile and their use as carriers for targeted delivery.

The formation in aqueous media of molecular nanoparticles from a bolaamphiphile (SucIleCsa) incorporating a disulfide moiety is described. The particles can be loaded efficiently with the lipophilic mitochondrial marker DiOC6(3), quenching its fluorescence, which is recovered upon reductive particle disassembly. DiOC6(3) transport into human colorectal adenocarcinoma cells (HT-29) is demonstrated using flow cytometry and confocal scanning fluorescence microscopy. A significant increase in intracellular fluorescence is observed when the cells are stimulated to produce glutathione (GSH). These new molecular nanoparticles can be considered a theranostic tool that simultaneously achieves targeted delivery of lipophilic substances and signals high levels of GSH.

Detection of subcellular nitric oxide in mitochondria using a pyrylium probe: assays in cell cultures and peripheral blood.

Fluorescent probes for the detection of intracellular nitric oxide (NO) are abundant, but those targeted to the mitochondria are scarce. Among those molecules targeting mitochondrial NO (mNO), the majority use a triphenylphosphonium (TPP) cation as a vector to reach such organelles. Here we describe a simple molecule (mtNOpy) based on the pyrylium structure, made in a few synthetic steps, capable of detecting selectively NO (aerated medium) over other reactive species. The calculated detection limit for mtNOpy is 88 nM. The main novelty of this probe is that it has a simple molecular architecture and can act both as a fluorogenic and as a mitochondriotropic agent, without using TPP. mtNOpy has been tested in two different scenarios: (a) in a controlled environment of cell line cultures (human colon carcinoma HT-29 cells and mouse macrophage RAW 264.7 cells), using confocal laser scanning microscopy, and (b) on a much more complex sample of peripheral blood, using flow cytometry. In the first context, mtNOpy has been found to be responsive (turn-on fluorescence) to exogenous and endogenous NO stimuli (via SNAP donor and LPS stimulation, respectively). In the second area, mtNOpy has been able to discriminate between NO-generating phagocytes (neutrophils and monocytes) from other leukocytes (NK, B and T cells).

Non-Polymeric Nanogels as Versatile Nanocarriers: Intracellular Transport of the Photosensitizers Rose Bengal and Hypericin for Photodynamic Therapy.

The use of nanocarriers for intracellular transport of actives has been extensively studied in recent years and represents a central area of nanomedicine. The main novelty of this paper lies on the use of nanogels formed by a low-molecular-weight gelator (1). Here, non-polymeric, molecular nanogels are successfully used for intracellular transport of two photodynamic therapy (PDT) agents, Rose Bengal (RB) and hypericin (HYP). The two photosensitizers (PSs) exhibit different drawbacks for their use in clinical applications. HYP is poorly water-soluble, while the cellular uptake of RB is hindered due to its dianionic character at physiological pH values. Additionally, both PSs tend to aggregate precluding an effective PDT. Despite the different nature of these PSs, nanogels from gelator 1 provide, in both cases, an efficient intracellular transport into human colon adenocarcinoma cells (HT-29) and a notably improved PDT efficiency, as assessed by confocal laser scanning microscopy and flow cytometry. Furthermore, no significant dark toxicity of the nanogels is observed, supporting the biocompatibility of the delivery system. The developed nanogels are highly reproducible due to their non-polymeric nature, and their synthesis is easily scaled up. The results presented here thus confirm the potential of molecular nanogels as valuable nanocarriers, capable of entrapping both hydrophobic and hydrophilic actives, for PDT of cancer.

Fast immunosensing technique to detect Legionella pneumophila in different natural and anthropogenic environments: comparative and collaborative trials.

BACKGROUND: Legionellosis is an uncommon form of pneumonia. After a clinical encounter, the necessary antibiotic treatment is available if the diagnosis is made early in the illness. Before the clinical encounter, early detection of the main pathogen involved, Legionella pneumophila, in hazardous environments is important in preventing infectious levels of this bacterium. In this study a qualitative test based on combined magnetic immunocapture and enzyme-immunoassay for the fast detection of Legionella pneumophila in water samples was compared with the standard method, in both comparative and collaborative trials. The test was based on the use of anti-Legionella pneumophila antibodies immobilized on magnetic microspheres. The final protocol included concentration by filtration, resuspension and immunomagnetic capture. The whole assay took less than 1 hour to complete. RESULTS: A comparative trial was performed against the standard culture method (ISO 11731) on both artificially and naturally contaminated water samples, for two matrices: chlorinated tap water and cooling tower water. Performance characteristics of the test used as screening with culture confirmation resulted in sensitivity, specificity, false positive, false negative, and efficiency of 96.6%, 100%, 0%, 3.4%, and 97.8%, respectively. The detection limit at the level under which the false negative rate increases to 50% (LOD50) was 93 colony forming units (CFU) in the volume examined for both tested matrices. The collaborative trial included twelve laboratories. Water samples spiked with certified reference materials were tested. In this study the coincidence level between the two methods was 95.8%. CONCLUSION: Results demonstrate the applicability of this immunosensing technique to the rapid, simple, and efficient detection of Legionella pneumophila in water samples. This test is not based on microbial growth, so it could be used as a rapid screening technique for the detection of L. pneumophila in waters, maintaining the performance of conventional culture for isolation of the pathogen and related studies.

A critical role for TNFalpha in the selective attachment of mononuclear leukocytes to angiotensin-II-stimulated arterioles.

Angiotensin II (Ang-II) exerts inflammatory activity and is involved in different cardiovascular disorders. This study has evaluated the involvement of tumor necrosis factor alpha (TNFalpha) in the leukocyte accumulation elicited by Ang-II. Ang-II (1 nM intraperitoneally in rats) induced TNFalpha release at 1 hour followed by neutrophil and mononuclear cell recruitment. The administration of an antirat TNFalpha antiserum had no effect on Ang-IIinduced neutrophil accumulation but inhibited the infiltration of mononuclear cells and reduced CC chemokine content in the peritoneal exudate. Pretreatment with either an anti-TNFalpha or an anti-IL-4 antiserum decreased Ang-II-induced arteriolar mononuclear leukocyte adhesion by 68% and 60%, respectively, in the rat mesenteric microcirculation. While no expression of TNFalpha was found in the postcapillary venules of Ang-II-injected animals, this cytokine was clearly up-regulated in the arterioles. Stimulation of human umbilical arterial endothelial cells (HUAECs) or isolated human mononuclear cells with 1 microM Ang-II caused increased TNFalpha mRNA expression and protein. Neutralization of TNFalpha activity reduced Ang-II-induced MCP-1, MCP-3, and RANTES release from HUAECs and MIP-1alpha from blood cells. In conclusion, the selective mononuclear leukocyte adhesion to Ang-II-stimulated arterioles is largely mediated by TNFalpha in cooperation with constitutive IL-4. Therefore, neutralization of TNFalpha activity may help to prevent mononuclear cell infiltration and the progression of the atherogenic process.