Publications by authors named "Francisco Galindo"

54 Publications

Base excision repair causes age-dependent accumulation of single-stranded DNA breaks that contribute to Parkinson disease pathology.

Cell Rep 2021 Sep;36(10):109668

Department of Clinical Molecular Biology, University of Oslo, Oslo, Norway; Department of Clinical Molecular Biology, Akershus University Hospital, Lørenskog, Norway. Electronic address:

Aging, genomic stress, and mitochondrial dysfunction are risk factors for neurodegenerative pathologies, such as Parkinson disease (PD). Although genomic instability is associated with aging and mitochondrial impairment, the underlying mechanisms are poorly understood. Here, we show that base excision repair generates genomic stress, promoting age-related neurodegeneration in a Caenorhabditis elegans PD model. A physiological level of NTH-1 DNA glycosylase mediates mitochondrial and nuclear genomic instability, which promote degeneration of dopaminergic neurons in older nematodes. Conversely, NTH-1 deficiency protects against α-synuclein-induced neurotoxicity, maintaining neuronal function with age. This apparent paradox is caused by modulation of mitochondrial transcription in NTH-1-deficient cells, and this modulation activates LMD-3, JNK-1, and SKN-1 and induces mitohormesis. The dependance of neuroprotection on mitochondrial transcription highlights the integration of BER and transcription regulation during physiological aging. Finally, whole-exome sequencing of genomic DNA from patients with idiopathic PD suggests that base excision repair might modulate susceptibility to PD in humans.
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http://dx.doi.org/10.1016/j.celrep.2021.109668DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8441048PMC
September 2021

Photodynamic Inactivation of by PHEMA Films Loaded with Rose Bengal: Potentiation Effect of Potassium Iodide.

Polymers (Basel) 2021 Jul 6;13(14). Epub 2021 Jul 6.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Av. V. Sos Baynat s/n, 12071 Castellón, Spain.

Four formulations have been used to produce different poly(2-hydroxyethyl methacrylate) (PHEMA) thin films, containing singlet oxygen photosensitizer Rose Bengal (). The polymers have been characterized employing Thermogravimetric Analysis (TGA), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) and UV-vis Absorption Spectroscopy. When irradiated with white light (400-700 nm) films generated singlet oxygen (O), as demonstrated by the reactivity with O trap 9,10-dimethylanthracene (). Material with the highest loading (polymer , 835 nmol /g polymer) was able to perform up to ten cycles of oxygenation reactions at high conversion rates (ca. 90%). Polymer was also able to produce the complete eradication of a planktonic suspension of 8 log CFU/mL, when irradiated with white light (total dose 72 J/cm). The antimicrobial photodynamic effect was remarkably enhanced by adding potassium iodide (100 mM). In such conditions the complete bacterial reduction occurred with a total light dose of 24 J/cm. Triiodide anion (I) generation was confirmed by UV-vis absorption spectroscopy. This species was detected inside the PHEMA films after irradiation and at concentrations ca. 1 M. The generation of this species and its retention in the matrix imparts long-lasting bactericidal effects to the @PHEMA polymeric hydrogels. The polymers here described could find potential applications in the medical context, when optimized for their use in everyday objects, helping to prevent bacterial contagion by contact with surfaces.
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http://dx.doi.org/10.3390/polym13142227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8309320PMC
July 2021

Broad-Spectrum Photo-Antimicrobial Polymers Based on Cationic Polystyrene and Rose Bengal.

Front Med (Lausanne) 2021 24;8:641646. Epub 2021 May 24.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Castellón, Spain.

New strategies to fight bacteria and fungi are necessary in view of the problem of iatrogenic and nosocomial infections combined with the growing threat of increased antimicrobial resistance. Recently, our group has prepared and described two new readily available materials based on the combination of Rose Bengal (singlet oxygen photosensitizer) and commercially available cationic polystyrene (macroporous resin Amberlite® IRA 900 or gel-type resin IRA 400). These materials showed high efficacy in the antimicrobial photodynamic inactivation (aPDI) of . Here, we present the photobactericidal effect of these polymers against an extended group of pathogens like , and the opportunistic yeast using green light. The most interesting finding is that the studied materials are able to reduce the population of both Gram-positive and Gram-negative bacteria with good activity, although, for , in a moderate manner. In view of the results achieved and especially considering the inexpensiveness of these two types of photoactive polymers, we believe that they could be used as the starting point for the development of coatings for self-disinfecting surfaces.
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http://dx.doi.org/10.3389/fmed.2021.641646DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8180575PMC
May 2021

Assessing Sustainability in Cattle Silvopastoral Systems in the Mexican Tropics Using the SAFA Framework.

Animals (Basel) 2021 Jan 7;11(1). Epub 2021 Jan 7.

Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Av. Insurgentes Sur s/n, Ciudad Universitaria, México D.F 04510, Mexico.

The sub-humid native rainforest in Yucatan is one of the most endangered in Mexico. Cattle production is one of the main causes of land use change and silvopastoral systems are a feasible alternative. This work compares the sustainable performance of silvopastoral (native and intensive) and monoculture cattle farms in the state of Yucatan using the Sustainability Assessment for Food and Agriculture (SAFA) framework. Questionnaires and semi-structured interviews were applied in 9 farms. Responses were fed to the SAFA Tool to obtain sustainability polygons. Percentages of SAFA themes positively and negatively valuated were calculated. Native farms had positive ratings for Participation, Land, Biodiversity and Cultural Diversity, whereas intensive excelled on Holistic Management. Native farms had limited ratings for Decent Livelihood. Native farms (and one intensive silvopastoral farm) had the highest percentages of themes positively valuated compared to monocultures (and one intensive silvopastoral farm), which scored the lowest. Positive evaluations identified native systems as an option for sustainable production; however, areas of opportunity in all farms were discovered. This is the first comparative study using SAFA to evaluate differences in farming systems in the Mexican tropics, providing valuable information to generate policies and incentives on sustainable livestock production, as well as for improving evaluation tools for local application.
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http://dx.doi.org/10.3390/ani11010109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7827675PMC
January 2021

Photodynamic Inactivation of Biofilms Using a Hexanuclear Molybdenum Complex Embedded in Transparent polyHEMA Hydrogels.

ACS Biomater Sci Eng 2020 12 19;6(12):6995-7003. Epub 2020 Nov 19.

Departamento de Química Inórganica y Orgánica, Universitat Jaume I, Av. Sos Baynat s/n, 12071 Castellón, Spain.

Three new photoactive polymeric materials embedding a hexanuclear molybdenum cluster (BuN)[MoI(CHCOO)] () have been synthesized and characterized by means of Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and emission spectroscopy. The materials are obtained in the format of transparent and thin sheets, and the formulations used to synthesize them are comprised of 2-hydroxyethyl methacrylate (HEMA), as a polymerizable monomer, and ethylene glycol dimethacrylate (EGDMA) or poly(ethylene glycol)dimethacrylate (PEGDMA), as cross-linkers. All the polymeric hydrogels generate singlet oxygen (O) upon irradiation with visible light (400-700 nm), as demonstrated by the reactivity toward two chemical traps of this reactive species (9,10-dimethylanthracene and 1,5-dihydroxynaphthalene). Some differences have been detected between the photoactive materials, probably attributable to variations in the permeability to solvent and oxygen. Notably, one of the materials resisted up to 10 cycles of photocatalytic oxygenation reactions of 1,5-dihydroxynaphthalene. All three of the polyHEMA hydrogels doped with are efficient against biofilms when irradiated with blue light (460 nm). The material made with the composition of 90% HEMA and 10% PEGDMA () is especially easy to handle, because of its flexibility, and it achieves a notable level of bacterial population reduction (3.0 log CFU/cm). The embedding of in cross-linked polyHEMA sheets affords a protective environment to the photosensitizer against aqueous degradation while preserving the photochemical and photobactericidal activity.
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http://dx.doi.org/10.1021/acsbiomaterials.0c00992DOI Listing
December 2020

A cost-effective combination of Rose Bengal and off-the-shelf cationic polystyrene for the photodynamic inactivation of Pseudomonas aeruginosa.

Mater Sci Eng C Mater Biol Appl 2020 Dec 24;117:111302. Epub 2020 Jul 24.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071 Castellón, Spain. Electronic address:

Two new photoactive materials have been prepared, characterized and tested against Pseudomonas aeruginosa bacteria (planktonic suspension). The synthesis of the polymeric photosensitizers can be made at a multigram scale, in few minutes, starting from inexpensive and readily available materials, such as Rose Bengal (photosensitizer) and ion exchange resins Amberlite® IRA 900 (macroporous) or IRA 400 (gel-type) as cationic polystyrene supports. The most notable feature of these systems is their notable bactericidal activity in the dark (4-5 log CFU/mL reduction of the population of P. aeruginosa) which becomes enhanced upon irradiation with visible light (to reach a total reduction of 8 log CFU/mL for the macroporous polymer at a fluence of 120 J/cm using green light of 515 nm).
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http://dx.doi.org/10.1016/j.msec.2020.111302DOI Listing
December 2020

Photobehavior of the antipsychotic drug cyamemazine in a supramolecular gel protective environment.

J Photochem Photobiol B 2020 Jan 6;202:111686. Epub 2019 Nov 6.

Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain. Electronic address:

In this work, a molecular hydrogel made of gelator (S)-4-((3-methyl-1-(nonylamino)-1-oxobutan-2-yl)amino)-4-oxobutanoic acid (SVN) has been employed as soft container to modify the photochemical and photophysical behavior of the antipsychotic drug cyamemazine (CMZ). The interaction of CMZ with the gel network has been evidenced by fluorescence spectroscopy through a hypsochromic shift of the emission band (from λ = 521 nm in solution to λ = 511 nm in the gel) and an increase of the fluorescence lifetime (5.6 ns in PBS vs. 7.2 ns in the gel). In the laser flash photolysis experiments on CMZ/SVN systems, the CMZ triplet excited state (CMZ*), monitored at λ = 320 nm, has been more efficiently generated and became much longer-lived than in solution (2.7 μs vs. 0.7 μs); besides, photochemical ionization leading to the radical cation CMZ was disfavored. In the steady-state experiments, photooxidation of CMZ to afford the N,S-dioxide derivative CMZ-SONO has been retarded in the gel, which provides a more lipophilic and constrained microenvironment. Both the photophysical properties and the photoreactivity are in agreement with CMZ located in a less polar domain when entrapped in the supramolecular gel, as result of the interaction of the drug with the fibers of the supramolecular SVN gel.
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http://dx.doi.org/10.1016/j.jphotobiol.2019.111686DOI Listing
January 2020

Liposome-Enveloped Molecular Nanogels.

Langmuir 2019 10 4;35(41):13375-13381. Epub 2019 Oct 4.

Departament de Química Inorgànica i Orgànica , Universitat Jaume I , Avda. Sos Baynat s/n , 12071 Castelló de la Plana , Spain.

Novel [email protected] particles were prepared by pH-triggered molecular gel formation inside of liposomes loaded with a low-molecular weight gelator derived from l-valine (). Liposome formation was carried out using l-α-phosphatidylcholine (PC) and cholesterol as components of the lipid bilayer. Molecular hydrogelator and pyranine, a ratiometric fluorescent pH probe, were entrapped in the liposomes at pH 9 and posterior acidification with d-glucono-1,5-lactone to pH 5-6 provoked intraliposomal gel formation. Removal of the lipid bilayer with sodium dodecyl sulfate yielded naked nanogel particles. The systems were characterized by transmission electron microscopy and dynamic light scattering. The [email protected] were loaded with doxorubicin, showing a similar release than that observed for liposomes. The hybrid particles described here are the first case of nonpolymeric [email protected] systems reported. This type of nanocarriers merges the benefits of liposomal vehicles with the inherent stimuli responsiveness and enhanced biocompatibility of hydrogels formed by low-molecular weight molecules, foretelling a potential use in environmentally sensitive drug release.
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http://dx.doi.org/10.1021/acs.langmuir.9b02282DOI Listing
October 2019

Self-Assembly Controls Reactivity with Nitric Oxide: Implications for Fluorescence Sensing.

ACS Omega 2018 Nov 15;3(11):15538-15545. Epub 2018 Nov 15.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Avda. Sos Baynat s/n, 12071 Castellón, Spain.

Three molecules containing the fluorophore 4-amino-1,8-naphthalimide (ANI) and showing different tendencies to self-assembly in aqueous environment have been prepared and fully characterized. The fluorescence emissions of two of these compounds in aqueous solutions are efficiently quenched in the presence of nitric oxide (NO) in aerated medium. Nuclear magnetic resonance and mass spectrometry techniques indicate that NO/O induces deamination of the ANI fluorophore, resulting in nonemissive 1,8-naphtalimide derivatives. It is found that the reactivity toward NO/O is regulated by the different aggregation modes presented by the molecules in aqueous medium. In this way, the molecules displaying fluorescence response toward NO/O are those with weak self-association properties whereas the compound with a high hydrophobic character (self-assembling into large nanoparticles) is insensitive to this species. Ultimately, the results described here could not only set the basis for the design of fluorescent bioprobes for NO/O based on ANI derivatives or other monoamino compounds but also could raise awareness about the importance of supramolecular interactions for the design of chemosensors.
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http://dx.doi.org/10.1021/acsomega.8b01869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6643459PMC
November 2018

Photoactive Hexanuclear Molybdenum Nanoclusters Embedded in Molecular Organogels.

Inorg Chem 2019 Jul 5;58(14):8900-8905. Epub 2019 Jul 5.

Departamento de Química Inorgánica y Orgánica , Universitat Jaume I , Avenida Sos Baynat s/n , Castellón 12071 , Spain.

Hexanuclear molybdenum clusters are attractive species because of their outstanding photonic properties, and in the past they have been attached to a variety of supports such as organic polymers and inorganic nanoparticles, as described in the recent literature. Here, a cluster of the formula TBA[MoIAc] (TBA = tetrabutylammonium; Ac = acetate) has been supported on molecular organogels for the first time, resulting in a new soft material with remarkable photoactivity. Electron and confocal microscopic analyses showed the alignment of the nanoclusters to 1D self-assembled fibers formed by the organic gelator, and emission spectroscopy corroborated the interaction of the emissive clusters with such fibrillary structures. The new hybrid system is a deep-red emissive material (phosphorescence maximum at ca. 680 nm), with chromatic coordinates = 0.725 and = 0.274, capable of efficiently generating singlet oxygen (O) upon illumination with white light, as demonstrated by the photooxygenation of 9,10-dimethylanthracene and 1,5-dihydroxynaphthalene. The organogels can been made in dichloromethane and toluene and in both solvents display phosphorescence emission and photocatalytic properties.
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http://dx.doi.org/10.1021/acs.inorgchem.9b00916DOI Listing
July 2019

In between molecules and self-assembled fibrillar networks: highly stable nanogel particles from a low molecular weight hydrogelator.

Soft Matter 2019 Apr;15(17):3565-3572

Departament de Química Inorgànica i Orgànica, Universitat Jaume I, Avda. Sos Baynat s/n, 12071 Castelló, Spain.

The preparation of molecular, non-polymeric nanogels from a low molecular weight hydrogelator is reported. The molecular nanogels are expected to overcome issues associated with the use of polymeric nanogels in biomedicine such as biodegradability, stimuli responsiveness, polydispersity, and batch-to-batch reproducibility. Nanogels formed by compound 1 were reproducibly prepared by sonication of a xerogel in PBS, with a total concentration of ca. 2 mM. The intensity averaged diameter of ca. 200 nm was determined by DLS. Electron microscopy (TEM and cryo-TEM) showed spherical particles. Light scattering (SALS) indicates that water is the main component of the nanoparticles, and the concentration of 1 in the nanogels is ca. 3 mg mL-1. These particles can be considered to constitute an intermediate state between free molecules and self-assembled fibrillar networks. The nanogels present excellent temporal and thermal stability and accessible hydrophobic domains, as demonstrated by the incorporation of the fluorescent dye Nile Red.
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http://dx.doi.org/10.1039/c9sm00252aDOI Listing
April 2019

Insights into the aggregation-induced emission of 1,8-naphthalimide-based supramolecular hydrogels.

Nanoscale 2018 Sep;10(36):17060-17069

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071, Castellón, Spain.

The study of aggregation-induced emission (AIE) of a series of 1,8-naphthalimide derivatives in aqueous media is reported herein. Some of these molecules constitute the first examples of 1,8-naphthalimide-containing amino acid derivatives that form hydrogels with excellent photophysical and mechanical properties. The present study provides further insights for the rational design of water-compatible stimuli-responsive photonic materials presenting AIE. AIE was quantitatively evaluated by measuring the fluorescence quantum yields of the molecules. Gelators 1 and 2 exhibit self-assembled fibrillar morphologies and present the best performance regarding the AIE effect, showing a remarkable enhancement in fluorescence intensity of 4700% and reaching a notable fluorescence quantum yield (Φf) of 30%. Non-gelator molecules 6 and 7 form nanoparticles, which also present AIE, but with emissions corresponding to their excimers. Therefore, the AIE intensity and wavelength are regulated by the type of aggregate morphology: fibers, nanoparticles or soluble species.
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http://dx.doi.org/10.1039/c8nr03755hDOI Listing
September 2018

Synthesis, spectroscopic studies and biological evaluation of acridine derivatives: The role of aggregation on the photodynamic efficiency.

Bioorg Med Chem Lett 2018 03 3;28(5):869-874. Epub 2018 Feb 3.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071 Castellón, Spain. Electronic address:

Two new photoactive compounds (1 and 2) derived from the 9-amidoacridine chromophore have been synthesized and fully characterized. Their abilities to produce singlet oxygen upon irradiation have been compared. The synthesized compounds show very different self-aggregating properties since only 1 present a strong tendency to aggregate in water. Biological assays were conducted with two cell types: hepatoma cells (Hep3B) and human umbilical vein endothelial cells (HUVEC). Photodynamic therapy (PDT) studies carried out with Hep3B cells showed that non-aggregating compound 2 showed photoxicity, ascribed to the production of singlet oxygen, being aggregating compound 1 photochemically inactive. On the other hand suspensions of 1, characterized as nano-sized aggregates, have notable antiproliferative activity towards this cell line in the dark.
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http://dx.doi.org/10.1016/j.bmcl.2018.02.005DOI Listing
March 2018

Sizing Down a Supramolecular Gel into Micro- and Nanoparticles.

Langmuir 2017 10 25;33(39):10322-10328. Epub 2017 Sep 25.

Departament de Química Inorgànica i Orgànica, Universitat Jaume I , Avda. Sos Baynat s/n, 12071 Castellón, Spain.

A low molecular weight gelator with a fluorescent 1,8-naphthalimide unit forms micro- and nanoparticles in aqueous media. Slow addition of a DMSO solution of the gelator into water affords either a self-assembled fibrillar network, sheaf-like microparticles, or nanoparticles depending to the concentration used in the experiment. The micro- and nanoparticles were characterized by dynamic light scattering (DLS), electron microscopy, and fluorescence measurements. In an initial assay of particle loading, Rose Bengal and Rhodamine 123 were shown to be incorporated in the particles. Light-promoted singlet oxygen generation capabilities of Rose Bengal were modulated by its incorporation in the particles. Additionally, the particles were found to promote the transport of Rhodamine 123 into human lung carcinoma live cells. These results indicate that nanoparticles arising from low molecular weight gelators may represent a new type of nanocarriers, being a potential alternative to polymeric nanogels used in nanomedicine.
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http://dx.doi.org/10.1021/acs.langmuir.7b02440DOI Listing
October 2017

Superior performance of macroporous over gel type polystyrene as a support for the development of photo-bactericidal materials.

J Mater Chem B 2017 Aug 20;5(30):6058-6064. Epub 2017 Jul 20.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071, Castellón, Spain.

A hexanuclear molybdenum cluster [MoIAc] (1) has been ionically bound onto macroporous (P) and gel-type (P) resins and their performance as materials for the photodynamic inactivation of microorganisms has been studied. It has been found that [email protected] in combination with light is able to reduce 99.999999% of the population of Gram-positive Staphylococcus aureus whereas the activity of [email protected] is limited to a 99.99% reduction at the same light dose. The same trend is observed with Gram-negative Pseudomonas aeruginosa. A comprehensive study of both materials has been performed using confocal laser scanning microscopy, thermogravimetric analysis, nitrogen porosimetry, steady state and time resolved fluorometries and diffuse reflectance spectroscopy. The photochemical generation of singlet oxygen (O) has been assessed using 9,10-dimethylanthracene as a trap for this reactive oxygen species. It can be concluded that the nature of the polymeric support is of paramount importance for the development of surfaces with bactericidal properties.
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http://dx.doi.org/10.1039/c7tb01478cDOI Listing
August 2017

The interaction of amino acids with macrocyclic pH probes of pseudopeptidic nature.

Photochem Photobiol Sci 2017 Aug;16(8):1320-1326

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Av. Sos Baynat, s/n, E-12071 Castellón, Spain.

The fluorescence quenching, by a series of amino acids, of pseudopeptidic compounds acting as probes for cellular acidity has been investigated. It has been found that amino acids containing electron-rich aromatic side chains like Trp or Tyr, as well as Met quench the emission of the probes mainly via a collisional mechanism, with Stern-Volmer constants in the 7-43 M range, while other amino acids such as His, Val or Phe did not cause deactivation of the fluorescence. Only a minor contribution of a static quenching due to the formation of ground-state complexes has been found for Trp and Tyr, with association constants in the 9-24 M range. For these ground-state complexes, a comparison between the macrocyclic probes and an open chain analogue reveals the existence of a moderate macrocyclic effect due to the preorganization of the probes in the more rigid structure.
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http://dx.doi.org/10.1039/c7pp00167cDOI Listing
August 2017

Thermally Regulated Reversible Formation of Vesicle-Like Assemblies by Hexaproline Amphiphiles.

J Phys Chem B 2017 08 2;121(31):7443-7446. Epub 2017 Aug 2.

Department of Chemistry, University of Reading, Whiteknights , Reading RG6 6AD, U.K.

Peptides composed of hexaproline and glutamic acid (PE) or lysine (PK) as C-terminal units show thermally promoted aggregation, affording vesicle-like assemblies upon heating to 80 °C. The aggregation is analyzed by dynamic light scattering (DLS), with number-averaged diameters of ca. 600 and 300 nm, respectively, for PE and PK. NMR studies reveal that upon heating the amount of NMR-visible species is reduced to ca. 50% and that an important conformational change is experienced by the molecules in solution. Circular dichroism (CD) shows that at 20 °C the peptides present a polyproline II (PP-II) conformation which is disorganized upon heating. Scanning electron microscopy for samples which were fast frozen at 80 °C reveals vesicle-like assemblies. Using pyrene as a fluorescence probe, a critical aggregation concentration of ca. 30 μM was estimated for PE, while that of PK was above 0.6 mM. The aggregation process is found to be fully reversible and could serve as a basis for development of stimuli responsive carriers.
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http://dx.doi.org/10.1021/acs.jpcb.7b06167DOI Listing
August 2017

Deamidation of pseudopeptidic molecular hydrogelators and its application to controlled release.

J Colloid Interface Sci 2017 Nov 3;505:1111-1117. Epub 2017 Jul 3.

Departament de Química Inorgànica i Orgànica, Universitat Jaume I, 12071 Castelló, Spain. Electronic address:

Hypothesis: The incorporation of a succinic acid-derived moiety in amino acid derivatives would favor an intramolecular catalysis of a deamidation reaction. Such reaction would permit controlled disassembly of molecular hydrogelators and the use of the hydrogels for controlled release of actives.

Experimental: Low molecular weight hydrogelators containing a succinic acid-derived moiety were prepared by conventional organic synthesis procedures. Hydrogels were examined by electron microscopy and HNMR studies were carried out to evaluate the solubility in water of the hydrogelators and the deamidation reaction. Liberation of Rose Bengal entrapped in the hydrogels was monitored by UV-Vis spectroscopy.

Findings: Molecular hydrogels formed by pseudopeptidic derivatives of l-valine suffer a thermal deamidation reaction, leading to partial disassembly. The succinic acid-derived moiety present in the gelators is responsible of intramolecular catalysis of a deamidation reaction. Such neighboring group effect is reminiscent of biochemical processes such as protein deamidation and self-excision of inteins. It has been found that the thermodynamic equilibrium of the deamidation reaction is regulated by the efficiency of hydrogelation. As a proof of concept, the thermally promoted deamidation is applied to controlled release of Rose Bengal.
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http://dx.doi.org/10.1016/j.jcis.2017.07.003DOI Listing
November 2017

Novel fluorescent anthracene-bodipy dyads displaying sensitivity to pH and turn-on behaviour towards Cu(ii) ions.

Org Biomol Chem 2017 Apr;15(14):3013-3024

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda.Sos Baynat s/n, 12071, Castellón, Spain.

Three bichromophoric compounds containing anthracene and bodipy moieties connected by different spacers have been synthesized and fully characterized. The set of spacers comprises a variety of bridges (short and flexible 1,2-diaminoethane in compound 1a, long and flexible 1,8-diaminooctane in compound 1b and short and rigid piperazine in compound 1c). The new compounds show interchromophoric communication via Electronic Energy Transfer (EET). When anthracene is excited, the energy is efficiently transferred to the bodipy moiety. The emission of the acceptor is partially quenched in dyad 1a but remarkably not in 1b and 1c. In an aqueous environment, the fluorescence of the new compounds display sensitivity to pH (emissive at acidic values and non-emissive at neutral ones), a typical behaviour of photoinduced electron-transfer (PET) probes, but with remarkable differences in the pK of each compound, attributable to the nature of the linker. Additionally, the behaviour in the presence of several metallic cations (Cu, Ni, Cd, Zn) has been studied, and a turn-on response towards Cu in water at neutral pH has been found.
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http://dx.doi.org/10.1039/c7ob00274bDOI Listing
April 2017

Influence of polymer composition on the sensitivity towards nitrite and nitric oxide of colorimetric disposable test strips.

Environ Sci Pollut Res Int 2017 Feb 21;24(4):3448-3455. Epub 2016 Nov 21.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Av. Sos Baynat, s/n, E-12071, Castellón, Spain.

The influence of polymer composition on the sensitivity towards nitrite (NO) and nitric oxide (NO) of a series of 19 polymeric hydrogel films has been studied. The polymers, based on the hydrophilic monomer 2-hydroxyethylmethacrylate (HEMA), are able to encapsulate the colorimetric indicator 1,2-diaminoanthraquinone (DAQ) and to respond to NO and NO by visual changes. In the case of nitrite, the calculated limits of detection (LOD) for two of the polymeric sensors (10 μM) are very close to the sensitivity estimated for free DAQ in solution (LOD 5 μM), but with the advantage of a solid supported sensor with the format of a disposable test-strip made with affordable starting chemicals. The results are interpreted taking into account the nature and proportions of monomers and cross-linkers used for the synthesis of polymers. Key factors for obtaining sensitive materials are the hydrophilic character of the film along with the utilization of low levels of cross-linker and the use of an acidic monomer, like acrylic acid, as a building block.
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http://dx.doi.org/10.1007/s11356-016-8068-0DOI Listing
February 2017

A photobleaching resistant polymer supported hexanuclear molybdenum iodide cluster for photocatalytic oxygenations and photodynamic inactivation of Staphylococcus aureus.

J Mater Chem B 2016 Sep 30;4(36):5975-5979. Epub 2016 Aug 30.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071, Castellón, Spain.

The ability of a hexanuclear molybdenum cluster, [MoI(CHCOO)], to carry out, upon irradiation, singlet oxygen mediated photocatalytic oxygenation reactions has been tested. This complex has been also supported on a solid polymeric matrix, yielding an immobilized photosensitizer with remarkable photostability and recyclability. Preliminary studies of antibacterial photoinactivation of Staphylococcus aureus have been conducted, with positive results.
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http://dx.doi.org/10.1039/c6tb01966hDOI Listing
September 2016

West Nile Virus in Resident Birds from Yucatan, Mexico.

J Wildl Dis 2016 Jan 5;52(1):159-63. Epub 2015 Nov 5.

2 Departamento de Etología, Fauna Silvestre y Animales de Laboratorio, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de Mexico, Av. Universidad #3000, Delegación Coyoacán, Mexico DF, CP 04510.

West Nile virus (WNV) in the Americas is thought to be transported at large spatial scales by migratory birds and locally spread and amplified by resident birds. Local processes, including interspecific interactions and dominance of passerine species recognized as competent reservoirs, may boost infection and maintain endemic cycles. Change in species composition has been recognized as an important driver for infection dynamics. Due to migration and changes in species diversity and composition in wintering grounds, changes in infection prevalence are expected. To these changes, we used PCR to estimate the prevalence of WNV in wild resident birds during the dry and rainy seasons of 2012 in Yucatan, Mexico. Serum samples were obtained from 104 wild birds, belonging to six orders and 35 species. We detected WNV in 14 resident birds, representing 11 species and three orders. Prevalences by order was Passeriformes (27%), Columbiformes (6%), and Piciformes (33%). Resident birds positive to WNV from Yucatan may be indicative of local virus circulation and evidence of past virus transmission activity.
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http://dx.doi.org/10.7589/2015-02-046DOI Listing
January 2016

The synthesis of new fluorescent bichromophoric compounds as ratiometric pH probes for intracellular measurements.

Org Biomol Chem 2015 Jul;13(28):7736-49

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Campus del Riu Sec, Av. Sos Baynat, s/n, E-12071, Castellón, Spain.

Three different bichromophoric compounds (1-3) containing an aminomethyl anthracene moiety linked to a second chromophore (pyrene, 4-nitrobenzo-2-oxa-1,3-diazole (NBD) and dansyl) through a valine-derived pseudopeptidic spacer have been prepared and their fluorescent properties studied. The results obtained show that upon irradiation the photophysical behavior of these probes involves electronic energy transfer from the excited anthracene to the second chromophore and also intramolecular photoinduced electron transfer. The X-ray structure obtained for 3 reveals that the folding associated with the pseudopeptidic spacer favours a close proximity of the two chromophores. The emissive response of 3 is clearly dependent on the pH of the medium, hence this bichromophoric compound was shown to be an excellent ratiometric pH fluorescent sensor. The emission intensity due to the anthracene moiety exhibits a decrease at neutral-basic pH values that is concomitant with an increase in the intensity arising from the dansyl fluorophore. These properties make this compound a good candidate for biological pH sensing as has been confirmed by preliminary studies with RAW 264.7 macrophage cells imaged by means of confocal fluorescence microscopy with an average pH estimation of 5.4-5.8 for acidic organelles.
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http://dx.doi.org/10.1039/c5ob00704fDOI Listing
July 2015

Recognition of free tryptophan in water by synthetic pseudopeptides: fluorescence and thermodynamic studies.

Chemistry 2014 Jun 30;20(24):7465-78. Epub 2014 Apr 30.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Av. Sos Baynat, s/n, E-12071 Castellón (Spain), Fax: (+34) 964728214.

Pseudopeptidic receptors containing an acridine unit have been prepared and their fluorescence response to a series of amino acids was measured in water. Free amino acids, not protected either at the C or the N terminus, were used for this purpose. The prepared receptors display a selective response to tryptophan (Trp) versus the other assayed amino acids under acidic conditions. The macrocyclic nature of the receptor is important as the fluorescence quenching is higher for the macrocyclic compound than for the related open-chain receptor. Notably, under the experimental acidic conditions used, both the receptor and guest are fully protonated and positively charged; thus, the experimental results suggest the formation of supramolecular species that contain two positively charged organic molecular components in proximity stabilized through aromatic-aromatic interactions and a complex set of cation-anion-cation interactions. The selectivity towards Trp seems to be based on the existence of a strong association between the indole ring of the monocharged amino acid and the acridinium fragment of the triprotonated form of the receptor, which is established to be assisted by the interaction of the cationic moieties with hydrogen sulfate anions.
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http://dx.doi.org/10.1002/chem.201304851DOI Listing
June 2014

Turn-on fluorescent probes for nitric oxide sensing based on the ortho-hydroxyamino structure showing no interference with dehydroascorbic acid.

Chem Commun (Camb) 2014 Apr 24;50(27):3579-81. Epub 2014 Feb 24.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Avda. Sos Baynat s/n, 12071, Castellón, Spain.

A new family of fluorescent synthetic molecular probes for nitric oxide sensing based on ortho-hydroxyamino-triarylpyrylium salts is presented.
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http://dx.doi.org/10.1039/c3cc49555hDOI Listing
April 2014

Fluorescent macrocyclic probes with pendant functional groups as markers of acidic organelles within live cells.

Org Biomol Chem 2014 Feb 9;12(5):823-31. Epub 2013 Dec 9.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Av. Sos Baynat, s/n, E-12071 Castelló de la Plana, Spain.

A new family of acidity sensitive fluorescent macrocycles has been synthesized and fully characterized. Their photophysical properties including emission quantum yield and fluorescence lifetime have been determined. The acid-base properties of the new molecules can be tuned by the incorporation of pendant functional groups. The nature of such functional groups (carboxylic acid or ester) influences dramatically the pKa of the probes, two compounds of which exhibit low values. Preliminary intracellular studies using confocal microscopy together with emission spectra of the probes from the cellular environment have shown that the synthesized fluorescent macrocycles mark the acidic organelles of RAW 264.7 macrophage cells.
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http://dx.doi.org/10.1039/c3ob41773eDOI Listing
February 2014

Singlet oxygen generation by photoactive polymeric microparticles with enhanced aqueous compatibility.

Environ Sci Pollut Res Int 2014 Oct 24;21(20):11884-92. Epub 2013 Nov 24.

Departamento de Química Inorgánica y Orgánica, Universitat Jaume I, Av. Sos Baynat, s/n, 12071, Castellón, Spain.

Two new photoactive materials compatible with environmentally friendly solvents (water and methanol) have been synthesized and characterized. They are comprised of a porous matrix of polystyrene and divinylbenzene with bound Rose Bengal and additional pendant groups added to increase the hydrophilicity (ethylenediamine and γ-gluconolactone). The new polymers are efficient photocatalysts capable of generating singlet oxygen after irradiation with visible light. Photochemical oxygenations of 9,10-anthracenedipropionic acid and 2-furoic acid have been carried out. The measured conversions indicate that the new supported photosensitizers are more effective than the parent hydrophobic polymer.
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http://dx.doi.org/10.1007/s11356-013-2311-8DOI Listing
October 2014

A photoinduced electron transfer-based nanoprobe as a marker of acidic organelles in mammalian cells.

Anal Bioanal Chem 2013 Jul 5;405(19):6197-207. Epub 2013 Apr 5.

School of Chemistry, University of East Anglia, Norwich, Norfolk, UK.

Photoinduced electron transfer (PET)-based molecular probes have been successfully used for the intracellular imaging of the pH of acidic organelles. In this study, we describe the synthesis and characterization of a novel PET-based pH nanoprobe and its biological application for the signaling of acidic organelles in mammalian cells. A fluorescent ligand sensitive to pH via the PET mechanism that incorporates a thiolated moiety was synthesized and used to stabilize gold nanoparticles (2.4 ± 0.6 nm), yielding a PET-based nanoprobe. The PET nanoprobe was unambiguously characterized by transmission electron microscopy, proton nuclear magnetic resonance, Fourier transform infrared, ultraviolet-visible absorption, and steady-state/time-resolved fluorescence spectroscopies which confirmed the functionalization of the gold nanoparticles with the PET-based ligand. Following a classic PET behavior, the fluorescence emission of the PET-based nanoprobe was quenched in alkaline conditions and enhanced in an acidic environment. The PET-based nanoprobe was used for the intracellular imaging of acidic environments within Chinese hamster ovary cells by confocal laser scanning microscopy. The internalization of the nanoparticles by the cells was confirmed by confocal fluorescence images and also by recording the fluorescence emission spectra of the intracellular PET-based nanoprobe from within the cells. Co-localization experiments using a marker of acidic organelles, LysoTracker Red DND-99, and a marker of autophagosomes, GFP-LC3, confirm that the PET-based nanoprobe acts as marker of acidic organelles and autophagosomes within mammalian cells.
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http://dx.doi.org/10.1007/s00216-013-6905-2DOI Listing
July 2013

Photoluminescence enhancement of CdSe quantum dots: a case of organogel-nanoparticle symbiosis.

J Am Chem Soc 2012 Dec 7;134(50):20554-63. Epub 2012 Dec 7.

Universitat Jaume I, Departamento de Química Inorgánica y Orgánica, Av. Sos Baynat, s/n, E-12071 Castellón, Spain.

Highly fluorescent organogels (QD-organogel), prepared by combining a pseudopeptidic macrocycle and different types of CdSe quantum dots (QDs), have been characterized using a battery of optical and microscopic techniques. The results indicate that the presence of the QDs not only does not disrupt the supramolecular organization of the internal fibrillar network of the organogel to a significant extent, but it also decreases the critical concentration of gelator needed to form stable and thermoreversible organogels. Regarding the photophysical properties of the QDs, different trends were observed depending on the presence of a ZnS inorganic shell around the CdSe core. Thus, while the core-shell QDs preserve their photophysical properties in the organogel medium, a high to moderate increase of the fluorescence intensity (up to 528%) and the average lifetime (up to 1.7), respectively, was observed for the core QDs embedded in the organogel. The results are relevant for the development of luminescent organogels based on quantum dots, which have potential applications as advanced hybrid materials in different fields.
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http://dx.doi.org/10.1021/ja310508rDOI Listing
December 2012

Localized intracellular pH measurement using a ratiometric photoinduced electron-transfer-based nanosensor.

Angew Chem Int Ed Engl 2012 Sep 21;51(38):9657-61. Epub 2012 Aug 21.

School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK.

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http://dx.doi.org/10.1002/anie.201203866DOI Listing
September 2012
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