Chitosan-Tricarbocyanine-Based Nanogels Were Able to Cross the Blood-Brain Barrier Showing Its Potential as a Targeted Site Delivery Agent.

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.

Benzoxaborole-grafted high molecular weight chitosan from prawn: Synthesis, characterization, target recognition and antibacterial properties.

Boronated polymers are in the focus of dynamic functional materials due to the versatility of the B-O interactions and accessibility of precursors. Polysaccharides are highly biocompatible, and therefore, an attractive platform for anchoring boronic acid groups for further bioconjugation of cis-diol containing molecules. We report for the first time the introduction of benzoxaborole by amidation of the amino groups of chitosan improving solubility and introducing cis-diol recognition at physiological pH.

Revisiting carboxylic group functionalization of silica sol-gel materials.

The carboxylic chemical group is a ubiquitous moiety present in amino acids, a ligand for transition metals, a colloidal stabilizer, and a weak acidic ion-exchanger in polymeric resins and given this property, it is attractive for responsive materials or nanopore-based gating applications. As the number of uses increases, subtle requirements are imposed on this molecular group when anchored to various platforms for the functioning of an integrated chemical system. In this context, silica stands as an inert and multipurpose platform that enables the anchoring of multiple chemical entities combined through several orthogonal synthesis methods on the interface.

Resveratrol encapsulation in high molecular weight chitosan-based nanogels for applications in ocular treatments: Impact on human ARPE-19 culture cells.

Oxidative stress and inflammation play a pivotal role in ocular diseases. Resveratrol (RSV) is a natural bioactive that has recently attracted attention due to it potent antioxidant and anti-inflammatory properties. However, RSV presents poor aqueous solubility and chemical instability.

Biological responses induced by high molecular weight chitosan administrated jointly with Platelet-derived Growth Factors in different mammalian cell lines.

In this work, we studied cellular responses known to be involved in tissue regeneration, such as proliferation, migration and tubulogenesis under High Molecular Weight Chitosan (HMWC) and recombinant Platelet-derived Growth Factor (PDGF) treatments using an in vitro cell culture approach. We also analysed changes in mitochondrial dynamics that could be associated with such biological responses. For this proposes, endothelial human cell lines (EA.

Benzoxaboroles as dynamic covalent receptors for bioconjugation and transport of nucleosides and related drugs: Proof of action in HeLa cells.

In this work we describe not previously explored binding studies on the reversible interaction of benzoxaborole with ligands of medical and pharmaceutical interest such as nucleosidic drugs gemcitabine and capecitabine, as well as the hydrophobic chemotherapeutic doxorubicin. We include functional derivatives of benzoxaborole such as a near infrared fluorescent boronolectine, Cy-Bx, The dynamic covalent interaction in physiological conditions was assessed by spectroscopic techniques yielding moderate to high binding affinities. The cytotoxic activity of the drugs upon conjugation to the boronolectins was evaluated revealing significant influence of the bioconjugation status on the cellular viability.

Multivalent assembly of a pyrene functionalized thio-N-acetylglucosamine: Synthesis, spectroscopic and WGA binding studies.

We introduce here a new fluorescent derivative of 1-thio-β-N-acetylglucosamine linked to a pyrene system through a triazolylpentyl spacer, designed to self-assemble into a multivalent glycocluster. The synthesis was achieved by efficient CuAAC click reaction between a pyrene functionalized with an azide group and a suitable alkynyl thiomonosaccharide. Spectroscopic studies by fluorometry indicated that the self-assembly in aqueous medium is modulated by concentration and pH changes, the latter due to the presence of the amino group close to the π system.

A Highly Sensitive Fluorogenic Probe for Imaging Glycoproteins and Mucine Activity in Live Cells in the Near-Infrared Region.

A novel fluorescent molecular probe is reported, which is able to detect glycoproteins, especially mucins, with high sensitivity and with a turn-on response along with a large Stokes shift (>130 nm), within the biologically active window. The probe contains an aminotricarbocyanine as the fluorescent reporter with a linked benzoboroxole as the recognition unit, which operates through a dynamic covalent reaction between the boronic hemiester residue of the receptor and cis-diols of the analyte. The superior selectivity of the probe is displayed by the labeling of mucins present in Calu-3 cells.

A silica supported tricarbocyanine based pH nanosensor with a large Stokes shift and a near infrared fluorescence response: performance in vitro and in live 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 SiO nanoparticles (Cy-PIP@SiO) and is capable of monitoring pH changes within the physiological range (pH 6-8). The Cy-PIP@SiO nanoparticles were successfully internalized by HeLa cells as shown by fluorescence confocal microscopy, while flow cytometry revealed pH fluctuations during the endocytic pathway.

Supramolecular Assembly of pH-Sensitive Triphenylene Derived π-Gelators and Their Application as Molecular Template for the Preparation of Silica Nanotubes.

The gelation properties and mode of self-assembly of six asymmetrical hexaether triphenylene derivatives mono-functionalized with carboxylic and primary amine groups were investigated. The presence of a carboxylic and amine group attached to the triphenylene core generated stable, thermo- and pH-sensitive supramolecular π-organogels with a reversible response to both stimuli. In order to understand the gelation process, we studied the effect of the spacer length and found a different gelation scope for the acid and basic derivatives that accounts for a different supramolecular self-assembly.

Recognition of saccharides in the NIR region with a novel fluorogenic boronolectin: in vitro and live cell labeling.

This work describes a novel mono-boronic acid derivative of a tricarbocyanine. The probe is a genuine near-infrared fluorescence emitter with improved properties such as a large Stokes shift, excellent water solubility and sensitive fluorogenicity upon binding to carbohydrates under physiological conditions.

Versatile supramolecular organogel with outstanding stability toward aqueous interfaces.

In this communication, we report on a novel and versatile low-molecular-weight organogelator. The methanolic gel exhibits an exceptional water-enhanced stability as evidenced by a 30 °C increase in Tg with up to 10%v/v of water. This atypical property not observed with other solvents makes of this supramolecular gel a highly stable matrix compatible with aqueous interfaces.

A versatile near-infrared asymmetric tricarbocyanine for zinc ion sensing in water.

We have synthesized a near-infrared emissive asymmetric tricarbocyanine conveniently functionalized to improve bioconjugation. The leading structure contains a versatile derivatization point at the meso position for facile radical-nucleophilic aromatic substitution. We have evaluated a DPEN (N,N-di(2-picolyl)ethylendiamine) derivative of this dye as a highly selective sensor for zinc (II) in aqueous medium, which performs in an appropriate sensitivity range for biological studies.

NIR fluorescent biotinylated cyanine dye: optical properties and combination with quantum dots as a potential sensing device.

We present a water soluble and fluorescent biotinylated probe derived from a carbocyanine dye. A high efficiency of energy transfer was measured when the dyes were placed on the surface of streptavidin conjugated quantum dots. The system is a model platform for potential application as a FRET-based fluorescent sensor.

Single-molecule redox blinking of perylene diimide derivatives in water.

Dynamic developments in ultrasensitive and superresolution fluorescence microscopy call for improved fluorescence markers with increased photostability and new functionalities. We used single-molecule spectroscopy to study water-soluble perylene dicarboximide fluorophores (PDI), which were immobilized in aqueous buffer by attaching the fluorophore to DNA. Under these conditions bright fluorescence, comparable to that of single-molecule compatible organic fluorophores, is observed with homogeneous spectral and fluorescence decay time distributions.

Photostability and spectral properties of fluorinated fluoresceins and their biarsenical derivatives: a combined experimental and theoretical study.

New fluorinated biarsenical derivatives with improved optical properties based on highly photostable analogs of fluorescein were recently introduced. The photophysical parameters of the triplet excited states as well as photosensitized oxidation reactions of these dyes were determined in order to investigate the influence of molecular structure on the exceptional photostability of these fluorophores. The lack of correspondence between triplet quantum yields and lifetimes with the photobleaching rates of some of the fluorophores of the series suggests that differential reactivities of the excited states with ground state oxygen accounts for the different photodegradation resistances.

Cytolocalization of the PhoP response regulator in Salmonella enterica: modulation by extracellular Mg2+ and by the SCV environment.

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.

Improved photostable FRET-competent biarsenical-tetracysteine probes based on fluorinated fluoresceins.

We have developed fluoro-substituted versions of the biarsenical-tetracysteine label FlAsH, exhibiting significant improvements in important properties over the original fluorescein derivative. In complexes with tetracysteine targets, F2FlAsH exhibits 50 times improved photostability, lower pH sensitivity, higher absorbance and quantum yield than FlAsH, and F4FlAsH adds a new color to the palette of biarsenical dyes. The two probes also provide a new FRET pair with a larger Ro value (54 A) than any previously obtained with biarsenical dyes.