Smart bactericides, design, synthesis and characterization.

Preventing microbial resistance to antibiotics is one of the most important challenges of our times, because multiresistant microorganisms are increasingly being reported. An approach based on silver nanoparticles is promising, given that this type of particles has been proven to exhibit antimicrobial activity. In addition, green strategies would be desirable, in which harmful chemicals are replaced by natural products to generate nanoparticles. Specifically, tannic acid (a phenolic metabolite present in many plants) has been used in addition to silver, and Coppo E et al. (2014) report their antimicrobial effects against various types of bacteria, including Escherichia coli (bacteria used in the model). Several synthesis methods have been previously described in combination with characterization by Raman spectroscopy (Dadosh 2009; Cao et al. 2014). However, we have found out that it is essential that the tannic acid solution used in the synthesis is neutralized before adding it to the silver solution to obtain the desired nanoparticles in a green synthesis. We have characterized our nanoparticles by UV-Vis spectrophotometry, and measured their hydrodynamic size and electrostatic stability by dynamic light scattering, which revealed an average size of 10-12 nm and a Zeta potential below -30mV. We have measured the antimicrobial activity using the minimum inhibitory concentration method, which, according to our preliminary results, indicate that said nanoparticles have a high antibacterial power against E.coli Dh5-α at low concentrations of the order of (15-20) μg of nanoparticles/ml. Our goals are to further adjust the range of concentrations and determine what would be the optimum concentration to ensure permanent antibacterial activity. With all the aforementioned, it can be stated that this type of nanoparticles is a very interesting proposal for the challenge of microbial resistance to antibiotics

Assessment by laser-induced breakdown spectroscopy of penetration depth in limestones of four nano-biocides based on silver/titanium nanoparticles

[Abstract]: Four biocidal treatments based on nanoparticles were designed and their penetration depths were char- acterized by laser-induced breakdown spectroscopy (LIBS) technique. This kind of biocidal nanoparticles are being studied to be employed in historic buildings and stone monuments due to their capability to inhibit the growth of biofoulings. The effectiveness of the treatment is related to the penetration depth of the nanoparticles in the limestone pore. For this reason, LIBS depth profiling was used in this work to characterize the diffusion of the nanoparticles in the limestone matrix and to compare the penetration depth of the different treatments. Four different nano-biocides based on silver/titanium dioxide nanopar- ticles were analysed by LIBS in limestone from Novelda quarry (Alicante, Spain). This limestone has been widely employed in both historical and contemporary buildings in Spain. The positive detection of the emission line of Ag at 338.289 nm was examined in the depth-related emission spectra as evidence of the presence of the silver nanoparticles and derived nanocomposites in the limestone matrix. The LIBS depth-profiles that were generated, showed a decrease of the Ag net signal with depth due to the diffusion of the nanoparticles in the limestone. Furthermore, the comparison of the in-depth sequences of spectra, and of the Ag depth profiles evidenced penetration differences between the nano-biocides which were explained by differences in the hydrodynamic diameter of the nanoparti- cles that would affect their diffusion in the limestone pore. The results of this assessment demonstrate the capability and potential of LIBS technique for the in-depth characterization of the nanoparticles and for the comparison of the effectiveness of nanoparticles biocidal treatments based on their penetration in the stone matrix

Microstructural Characterization of Silver Nanoparticles for Bioimaging Applications

Junta de Andalucía FQM-6615, PI0070, FQM31

Evaluación de TuFormulas. Diseño y aplicación de indicadores para medir el impacto y la sostenibilidad de este recurso educativo como herramienta de enseñanza y aprendizaje

Depto. de Química en Ciencias FarmacéuticasFac. de FarmaciaFALSEsubmitte

Silver/dioxide titanium nanocomposites as biocidal treatments on limestones

Biodegradation of stones is a common and undesirable alteration in historical buildings. Restorers have been using different treatments, especially chemical methods, to prevent biodeterioration. These treatments often have disadvantages such as low long-term effectiveness, high toxicity on human health and the environment and/or physicochemical incompatibility with the original stone (chromatic alteration or chemical degradation). In this research, different biocidal treatments based on silver and titanium dioxide nanocomposites have been tested on limestones from Utrera’s quarry (Seville, Spain), a stone employed in historical buildings in the south of Spain. Two AgNPs syntheses have been studied; the principal difference between them was the use of trisodium citrate as stabilizer. Optimum nanocomposite composition and dosage to minimize chromatic alteration after application of treatments without cut down the biocide effectiveness have been set up. Treatments based on silver-titanium dioxide (Ag/TiO2) nanocomposites stabilized with citrate have been able to keep clean the limestone due to the biopatina formation reduction and the surface color change has been below 10%.La biodegradación en piedra es una alteración común e indeseable en los edificios históricos. Los restauradores han estado utilizando diferentes tratamientos para la prevención del biodeterioro, especialmente métodos químicos. Estos tratamientos suelen tener ciertas desventajas, tales como baja durabilidad a largo plazo, alta toxicidad para el hombre y el medioambiente y/o su incompatibilidad físico-química con la piedra original (alteración cromática o degradación química). En esta investigación, diferentes tratamientos biocidas basados en nanopartículas de plata y dióxido de titanio han sido probados sobre calizas procedentes de la cantera de Utrera (Sevilla, España), piedra utilizada en la construcción de diferentes edificios históricos del sur de España. Para ello, dos síntesis de nanopartículas de plata han sido utilizadas, cuya principal diferencia estriba en el empleo de citrato sódico como estabilizante. La óptima composición y dosis de nanocompuestos que logra disminuir los incrementos de color del tratamiento sin mermar sus propiedades como biocida ha sido investigada. El nanocompuesto de plata/dióxido de titanio estabilizado con citrato ha permitido mantener limpia la piedra caliza, reduciendo la formación de biopátina y generando un cambio de color tras el ensayo menor del 10%

Síntesis de nuevos nanovectores para el diagnóstico y tratamiento del cáncer de próstata

Motivación: El cáncer de próstata es, globalmente, el segundo cáncer más diagnosticado en hombres y representa la segunda causa de muerte relacionada con el cáncer. En etapas avanzadas y metastásicos presentan un pobre pronóstico de tratamiento con terapias convencionales, como la quimioterapia, por lo que es crítico desarrollar estrategias de tratamiento que mejoren los resultados de las existentes. Además, los beneficios que ofrece la quimioterapia convencional se ven limitados por su toxicidad sistémica, y un punto clave de la investigación del cáncer es crear nuevas terapias selectivas que solventen dicho problema. Una de las aplicaciones más prometedoras de la nanotecnología en la terapia contra el cáncer es el uso de nanopartículas (NP) direccionadas a los tejidos diana cancerosos, ya que tienen el potencial de superar la toxicidad y limitaciones de eficacia asociadas a los agentes citotóxicos tradicionales. En este trabajo describimos la obtención de NP dirigidas contra el Antígeno de Membrana Específico de Próstata (PSMA), una glicoproteína integral de membrana que presenta una expresión abundante y restringida a las células del cáncer de próstata, particularmente en estadios avanzados y metastásicos.Métodos: Los precursores se han obtenido por dos rutas: Sucesivas reacciones de amidación entre los distintos componentes de las NP y “química click” (QC). Los intermedios se han caracterizado por Resonancia Magnética Nuclear y Espectroscopía de Masas de Alta Resolución. Tras su obtención, los precursores se han sonicado para obtener micelas y liposomas (tras irradiar con luz UV).Resultados: Se han logrado sintetizar NP lipídicas dirigidas contra PSMA, gracias al desarrollo de dos rutas sintéticas para obtener los precursores de las NP con rendimientos elevados, siendo la QC más sencilla y rápida. Estas NP lipídicas están formadas por una parte polar, constituida por un dipéptido (Glutamato–Lisina), que confiere a la NP la selectividad por PSMA, un espaciador polietilenglicol y una parte apolar (ácido 10,12-pentacosadiinoico).Conclusiones: La estructura y propiedades de las nanopartículas obtenidas es muy adecuada para el diseño de sistemas de direccionamiento selectivo de agentes quimioterapéuticos y de imagen, que pueden suponer mejoras en el diagnóstico y tratamiento del cáncer de próstata

Synthesis and characterization of nanoparticles of polyphenolic extracts for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a digestive tract disorder, of which two types are distinguished: ulcerative colitis (UC) and Crohn's disease (CD). In both cases, the disease progresses through periods of relapse and remission. Although the etiology of IBD is unknown, it is known to be a multifactorial disease that involves in its development environmental, genetic and immunological factors as well as alterations in the intestinal microbiota in its development. The prevalence and incidence of UC and CD have increased worldwide in recent decades, specially in Europe and North America. Polyphenols, and among them those from the maqui extract [1,2], are showing great potential in the treatment of IBD, but it remains a challenge to find a formulation that allows them to reach their site of action, the intestine, without lose their therapeutic properties. In this context, the objective of our work has been to develop formulations based on polymeric organic nanoparticles containing maqui polyphenolic extracts, for subsequent testing both in vitro, in cultures of colonic epithelial cells, and in vivo, in a murine model of Crohn's disease. Methods: We have encapsulated maqui polyphenolic extract in polymeric organic nanoparticles based on a co-precipitation method developed in our group [3]. We have tested the following encapsulation polymers: polyvinyl alcohol, polyethylene glycol, polyetherimide and polyvinylpyrrolidone, and obtained the best results with the last one. The obtained nanoparticles have been characterized, among others, by DLS, UV-Vis and FTIR. Results: We have managed to synthesize polymeric organic nanoparticles encapsulating maqui polyphenolic extract with and without tannic acid as an adjuvant. The nanoparticles have a suitable size for biomedical applications and high stability, as reflected by their zeta potential. The presence of the active principles has been validated by FTIR and its liberation’s profile has been established in the presence of an aqueous medium

Targeted multifunctional tannic acid nanoparticles

Tannic acid (TA) has multiple effects against cancer, being especially promising in those types that overexpress the epidermal growth factor receptor (EGFR), as TA modulates its activation and downstream signaling pathways, triggering apoptosis. Nonetheless, despite the important role of this receptor in the pathogenesis and progression of a wide variety of tumors, no TA systems targeted to this receptor have been described yet. In this work, we synthesize, characterize by physico-chemical techniques and study the cytotoxic effect and cell uptake of TA nanoparticles targeted to EGFR in both tumoral and normal human skin cells. Our nanoparticles exhibited an extremely high entrapment efficiency, and were only toxic for the tumoral cells. The uptake assay demonstrated that nanoparticles are able to enter the cells through a receptor-mediated mechanism. Furthermore, we have included fluorescent markers in these nanoparticles to combine imaging and therapeutic applications, thus building effectively a multifunctional tool for biomedicine.Junta de Andalucía (Proyecto de Investigación de Excelencia P10-FQM-6615 and PAIDI FQM319)Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea)Ministerio de Economía y Competitividad, Gobierno de España (Proyecto de Excelencia CTQ2013-48396-P)Junta de Andalucía (P10- FQM-06615

Innovative compounds to battle multiresistence to antibiotics: use of PVA-Tannic acid nanoparticles to inibit staphylococcus pseudointermedius growth

Antibiotic resistance is an increasing public health problem that affects numerous pathogens, including Staphylococcus pseudintermedius, which has a high prevalence of methicillin resistance and can be easily transmitted to humans. Nowadays, the scientific community is developing new compounds that not only improve classic therapies in fighting antibiotic resistances but also prevent its appearance, essential to maintain health protection. The main objective of the present study is to synthesize tannic acid and polyvinyl alcohol nanoparticles and to determine their potential as growth inhibitors for S. pseudintermedius, to be considered a potential alternative therapy. The study includes diameter and Z-potential measurements for nanoparticles characterization and antimicrobial effect assays with different nanoparticles concentrations. MIC90 is determined as 112 μg/mL. Nonetheless, further studies to identify the underlying action mechanisms of these nanoparticles are going on in our group