Electrochromic polyoxometalate material as a sensor of bacterial activity

L. fermentum, a bacterium of human microbiota, acts as an electron donor to the electrochromic [P2MoVI18O62]6. Since, the reductive capacity of L. fermentum correlates with its metabolic activity, the reaction with [P2MoVI18O62]6- affords a means of evaluating its activity. Following this logic, we have concluded that vancomycin severely affects the activity of L. fermentum whereas omeprazole does not.FQM368 Bionanopartículas Metálicas (BioNanomet)Departamento de Química InorgánicaThis work was funded by MINECO and FEDER (project CTQ2012-32236

Insights on the (Auto)Photocatalysis of Ferritin

Traditionally, ferritin has been considered a photocatalyst capable of photo-oxidizing organic molecules and transferring electrons to external electron acceptors when irradiated by UV–visible light. We have designed new approaches to resolve the uncertainties regarding its photocatalytical mechanism. Experiments with an Fe(II) chelator, an electrochromic indicator, and recombinant ferritin proteins indicate that the excited electrons at the conduction band of the ferritin core do not cross the protein shell. Instead, irradiation causes the electrons to reduce the ferrihydrite core to produce Fe(II) ions. These Fe(II) ions exit the protein shell to reduce electron acceptors. In the absence of electron acceptors or chelators, Fe(II) re-enters ferritin.This work was funded by MINECO and FEDER (CTQ2015-64538). N.S. would like to acknowledge funding from the U.S. Student Fulbright Scholarship

Artificial Magnetic Bacteria: Living Magnets at Room Temperature

"This is the peer reviewed version of the following article: Martín Marcos, M.A.; et al. Artificial Magnetic Bacteria: Living Magnets at Room Temperature. Advanced Functional Materials, 24(23): 3489-3493 (2014), which has been published in final form at http://dx.doi.org/10.1002/adfm.201303754 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."Biogenic magnetite is a fascinating example of how nature can generate functional magnetic nanostructures. Inspired by the magnetic bacteria, an attempt is made to mimic their magnetic properties, rather than their structures, to create living magnets at room temperature. The non-magnetic probiotic bacteria Lactobacillus fermentum and Bifidobacteria breve are used as bioplatforms to densely arrange superparamagnetic nanoparticles on their external surfaces, thus obtaining the artificial magnetic bacteria. Magnetic probiotic bacteria can be produced by using superparamagnetic maghemite nanoparticles assembled at their surfaces. They present a collective ferromagnetic phase at room temperature. The blocking temperature of these maghemite nanoparticles increases more than 100 K when assembled at the artificial magnetic bacteria.This work was funded by Biosearch S. A. (POSTBIO project-Agency for Innovation and Development of Andalucia IDEA) and by MINECO and FEDER (project CTQ2012–32236)

Identification of the key excreted molecule by Lactobacillus fermentum related to host iron absorption

We have taken a vital step towards understanding why probiotic bacteria increase iron absorption in the gastrointestinal tract. We show here that Lactobacillus fermentum, one of the main probiotics of the microbiota, exhibits an extraordinary ferric-reducing activity. This activity is predominantly due to an excreted molecule: p-hydroxyphenyllactic acid (HPLA). Reduction of Fe(III) to Fe(II) is essential for iron absorption in the gastrointestinal tract. By reducing Fe(III), HPLA boosts Fe(II) absorption through the DMT1 channels of enterocytes. An in vitro experiment tested and confirmed this hypothesis. This discovery opens new avenues for the treatment of iron deficiency in humans, one of the most common and widespread nutritional disorders in the world

Bacteria-Carried Iron Oxide Nanoparticles for Treatment of Anemia

The efficiency of maghemite nanoparticles for the treatment of anemia was sensibly higher when nanoparticles were incorporated onto the probiotic bacterium Lactobacillus fermentum (MNP-bacteria) than when administrated as uncoated nanoparticles (MNP). Plasma iron and hemoglobin, intestine expression of divalent metal transporter 1 (DMT1) and duodenal Cytochrome b (DcytB), as well as hepatic expression of the hormone hepcidin were fully restored to healthy levels after administration of MNP-bacteria but not of MNP. A magnetic study on biodistribution and biodegradation showed accumulation of maghemite nanoparticles in intestine lumen when MNP-bacteria were administrated. In contrast, MNP barely reached intestine. In vivo MRI studies suggested the internalization of MNP-bacteria into enterocytes, which did not occur with MNP. Transmission electronic microscopy confirmed this internalization. The collective analysis of results point out that L. fermentum is an excellent carrier to overcome the stomach medium and drive maghemite nanoparticles to intestine, where iron absorption occurs. Due the probiotic ability to adhere to the gut wall, MNP-bacteria internalize into the enterocyte, where maghemite nanoparticles are delivered, providing an adequate iron level into enterocyte. This paper advances a new route for effective iron absorption in the treatment of anemia.The efficiency of maghemite nanoparticles for the treatment of anemia was sensibly higher when nanoparticles were incorporated onto the probiotic bacterium Lactobacillus fermentum (MNP-bacteria) than when administrated as uncoated nanoparticles (MNP). Plasma iron and hemoglobin, intestine expression of divalent metal transporter 1 (DMT1) and duodenal Cytochrome b (DcytB), as well as hepatic expression of the hormone hepcidin were fully restored to healthy levels after administration of MNP-bacteria but not of MNP. A magnetic study on biodistribution and biodegradation showed accumulation of maghemite nanoparticles in intestine lumen when MNP-bacteria were administrated. In contrast, MNP barely reached intestine. In vivo MRI studies suggested the internalization of MNP-bacteria into enterocytes, which did not occur with MNP. Transmission electronic microscopy confirmed this internalization. The collective analysis of results point out that L. fermentum is an excellent carrier to overcome the stomach medium and drive maghemite nanoparticles to intestine, where iron absorption occurs. Due the probiotic ability to adhere to the gut wall, MNP-bacteria internalize into the enterocyte, where maghemite nanoparticles are delivered, providing an adequate iron level into enterocyte. This paper advances a new route for effective iron absorption in the treatment of anemia

Selecting FRET pairs for visualizing amyloid aggregation

This work was supported by grant CTQ2017–85658-R funded by MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa” and grants PID2019–104366RB-C22 and PID2020–114256RBI00 funded by MCIN/AEI/10.13039/ 501100011033. A.R.-A. thanks the Spanish Ministerio de Educación y Formación Profesional for an FPU Ph.D. studentship.In a recent work, we reported a methodology for imaging the different stages of amyloid aggregation in quantitative multiparametric dual-color fluorescence lifetime imaging (FLIM) and superresolution microscopy by using a pair of dyes capable of binding aggregates and undergoing subsequent intra-aggregate energy transfer (FRET) (RuizArias et al. Sensors Actuat. B, 2022, 350:130882). In this microarticle we present the optimization process for choosing the best pair of dyes through a screening of different naphthalimides and quinolimides and other known amyloid-binding dyes.Spanish Ministerio de Educación y FormaciónGrant CTQ2017–85658-R funded by MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa”Grants PID2019–104366RB-C22 and PID2020–114256RBI00 funded by MCIN/AEI/10.13039/ 50110001103

Magneto-optical hyperthermia agents based on probiotic bacteria loaded with magnetic and gold nanoparticles

This work was funded by the Ministerio de Ciencia, Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) through the projects PID2019- 111461GB-I00 to N.G. and J.M.DV, and PGC2018-096016-B-I00 to LG.). S.T. and J.J.C. acknowledge funding from the European Union’s Horizon 2020 research and innovation program under Grant 823717−ESTEEM3. A.G. acknowledges Junta de Andalucía for the postdoctoral contract within the PAIDI 2020 program (DOC_00791). Y.FA. thanks Santander-Universidad Zaragoza Fellowship program for her PhD position. J.M.D.L. acknowledges the financial support by the Spanish MCIN/AEI /10.13039/501100011033 through the project NanoSmart (RYC-2016-21042)Probiotic bacteria were used as carriers of metallic nanoparticles to develop innovative oral agents for hyperthermia cancer therapy. Two synthetic strategies were used to produce the different therapeutic agents. First, the probiotic bacterium Lactobacillus fermentum was simultaneously loaded with magnetic (MNPs) and gold nanoparticles (AuNPs) of different morphologies to produce AuNP+MNP-bacteria systems with both types of nanoparticles arranged in the same layer of bacterial exopolysaccharides (EPS). In the second approach, the probiotic was first loaded with AuNP to form AuNP-bacteria and subsequently loaded with MNP-EPS to yield AuNP-bacteria-EPS-MNP with the MNP and AuNP arranged in two different EPS layers. This second strategy has never been reported and exploits the presence of EPS–EPS recognition which allows the layer-by-layer formation of structures on the bacteria external wall. The AuNP+MNP-bacteria and AuNP-bacteria-EPS-MNP samples were characterized by scanning (SEM) and transmission electron microscopy (TEM), and UV-vis spectroscopy. The potential of these two heterobimetallic systems as magnetic hyperthermia or photothermal therapy agents was assessed, validating their capacity to produce heat either during exposure to an alternating magnetic field or a near-infrared laser light. The probiotic Lactobacillus fermentum has already been proposed as an oral drug carrier, able to overcome the stomach medium and deliver drugs to the intestines, and it is actually marketed as an oral supplement to reinforce the gut microbiota, thus, our results open the way for the development of novel therapeutic strategies using these new heterobimetallic AuNP/MNP-bacteria systems in the frame of gastric diseases, using them, for example, as oral agents for cancer treatment with magnetic hyperthermia and photothermal therapy.Ministerio de Ciencia, Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) through the project PID2019- 111461GB-I00Ministerio de Ciencia, Innovación y Universidades (MCIU), the Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) through the project PGC2018-096016-B-I00European Union’s Horizon 2020 research and innovation program under Grant 823717−ESTEEM3PAIDI 2020 program (DOC_00791)Spanish MCIN/AEI /10.13039/501100011033 through the project NanoSmart (RYC-2016-21042

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Apoferritin Amyloid-Fibril Directed the In Situ Assembly and/or Synthesis of Optical and Magnetic Nanoparticles

The coupling of proteins that can assemble, recognise or mineralise specific inorganic species is a promising strategy for the synthesis of nanoscale materials with a controllable morphology and functionality. Herein, we report that apoferritin protein amyloid fibrils (APO) have the ability to assemble and/or synthesise various metal and metal compound nanoparticles (NPs). As such, we prepared metal NP–protein hybrid bioconjugates with improved optical and magnetic properties by coupling diverse gold (AuNPs) and magnetic iron oxide nanoparticles (MNPs) to apoferritin amyloid fibrils and compared them to the well-known -lactoglobulin (BLG) protein. In a second approach, we used of solvent-exposed metal-binding residues in APO amyloid fibrils as nanoreactors for the in situ synthesis of gold, silver (AgNPs) and palladium nanoparticles (PdNPs). Our results demonstrate, the versatile nature of the APO biotemplate and its high potential for preparing functional hybrid bionanomaterials. Specifically, the use of apoferritin fibrils as vectors to integrate magnetic MNPs or AuNPs is a promising synthetic strategy for the preparation of specific contrast agents for early in vivo detection using various bioimaging techniques.Junta de Andalucía P18-FQM-1373MINECO Project PID2019-111461GB-10

Understanding the Formation of Apoferritin Amyloid Fibrils

We present the optimization of experimental conditions to yield long, rigid apoferritin protein amyloid fibrils, as well as the corresponding fibrillation pathway. Fibril growth kinetics was followed using atomic force microscopy (AFM), transmission electron microscopy (TEM), dynamic light scattering (DLS), circular dichroism (CD), fourier-transform infrared spectroscopy (FTIR), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Among the morphologies identified, we show that the conditions result in small aggregates, as well as medium and long fibrils. Extended incubation times led to progressive unfolding and hydrolysis of the proteins into very short peptide fragments. AFM, SDS-PAGE, and CD support a universal common fibrillation mechanism in which hydrolyzed fragments play the central role. These collective results provide convincing evidence that protein unfolding and complete hydrolysis of the proteins into very short peptide sequences are essential for the formation of the final apoferritin amyloid-like fibrils.Junta de Andalucia P11-FQM-8136 P18-RT-1373Ministry of Science and Innovation, Spain (MICINN)Instituto de Salud Carlos IIISpanish Government PID2019-111461GB-I00Boehringer Ingelhei