Editorial Special issue on nano-systems for antimicrobial therapy

Editorial of the Special issue on Nano-Systems for Antimicrobial Therap

Aceite foliar de Ocotea quixos (Lam.) Kosterm.

Los principales componentes identificados en el aceite esencial de las hojas de Ocotea quixos (Lam.) Kosterm. son: Cariofileno 19,029%, Humuleno 14,323% y Eremofileno 11,407%, aclarándose que éstos sobresalen de un total de 62 compuestos. La técnica utilizada para la extracción del aceite fue destilación con agua y vapor de agua, empleando un destilador de 250 litros de capacidad. La cantidad de aceite obtenida fue de 3 ml por cada 10 kg de hojas frescas. El aceite fue utilizado para un experimento de evaluación de actividad antimicrobiana y antifúngica, siendo el resultado la inhibición del crecimiento de cepas de Staphylococcus epidermidis, Staphylcoccus aureus, Escherichia coli, Candida albicans, Streptococos piogenes y Streptococcus mutans. Los resultados del experimento demostraron que el aceite foliar tiene una alta capacidad inhibitoria contra hongos (levaduras) y bacterias; así, se recomienda por un lado, continuar con análisis químicos más finos para determinar la naturaleza específica de los 62 compuestos y, por el otro, realizar ensayos con un número mayor de agentes patógenos

Strong coupling between excitons in organic semiconductors and Bloch Surface Waves

We report on the strong coupling between the Bloch surface wave supported by an inorganic multilayer structure and $J$-aggregate excitons in an organic semiconductor. The dispersion curves of the resulting polariton modes are investigated by means of angle-resolved attenuated total reflection as well as photoluminescence experiments. The measured Rabi splitting is 290 meV. These results are in good agreement with those obtained from our theoretical model

Análisis de la composición del aceite esencial de Myrcianthes rhopaloides (Kunth in H.B.K.) McVaugh, Myrtaceae, y evaluación de su actividad biológica

El estudio de la composición química del aceite esencial de la planta reconocida con el nombre vernáculo de arrayán y que pertenece a la especie Myrcianthes rhopaloides (Kunth in H.B.K.) McVaugh, familia Myrtaceae, fue realizado mediante la técnica de cromatografía de gases acoplada a masas, la que permitió identificar una mezcla de componentes mono y sesquiterpenos. Es así, que los principales compuestos que se destacaron fueron Linalol, Eucaliptol, D –Limoneno y Terpineol; seguidos, en menor proporción, de 4 Terpineol, cis Mirtanol, Cariofileno, ·-Cariofileno, Cadineno y Espatulenol.El efecto de la actividad antimicrobiana del aceite de arrayán evidenció una acción fuerte sobre microorganismos como Streptococcus mutans y Streptococcus pyogenes, menor sobre Staphilococcus aureus y Staphilococcus epidermidis, y ausente sobre Escherichia coli y Candida albicans

A bistren cryptand with a remote thioether function: Cu(ii) complexation in solution and on the surface of gold nanostars

A di-copper(ii) complex is formed in a bis-tren cage featuring a thioether function, capable of grafting on a monolayer of gold nanostars

Full-scale shake table tests of a reinforced concrete structure equipped with a novel active mass damper

This paper presents the results of an experimental program involving shake table testing of two full-scale reinforced concrete frame buildings. These tests were conducted to investigate the effectiveness and reliability of a newly proposed servo-hydraulic Active Mass Damper (AMD) that can be designed to enhance the target seismic performance of a building at multiple earthquake intensity levels. The two nominally identical case-study buildings were intentionally designed to exhibit a “soft story” mechanism at the first level when subject to ground shaking of sufficient intensity, but one was equipped with the newly proposed AMD, installed on the roof. The two specimens were then subject to the same loading protocol consisting of a ground shaking sequence of varying intensity, with the seismic input consisting of a selected natural ground motion. The experimental results demonstrated that the proposed AMD is extremely effective at enhancing building seismic performance. Specifically, the AMD provided peak displacement reductions in the order of 70% and was shown capable of absorbing more than 60% of the total input energy. As a consequence, the un-retrofitted structure suffered nontrivial structural and non-structural damage, while the AMD-retrofitted building remained virtually undamaged at all shaking intensities considered

Nanocomposite sprayed films with photo-thermal properties for remote bacteria eradication

Currently there is a strong demand for novel protective materials with effcient antibacterial properties. Nanocomposite materials loaded with photo-thermally active nanoparticles can offer promising opportunities due to the local increase of temperature upon near-infrared (NIR) light exposure capable of eradicating bacteria. In this work, we fabricated antibacterial films obtained by spraying on glass slides aqueous solutions of polymers, containing highly photo-thermally active gold nanostars (GNS) or Prussian Blue (PB) nanoparticles. Under NIR light irradiation with low intensities (0.35W/cm2) these films demonstrated a pronounced photo-thermal effect: 06Tmax up to 26.4 ffC for the GNS-containing films and 06Tmax up to 45.8 ffC for the PB-containing films. In the latter case, such a local temperature increase demonstrated a remarkable effect on a Gram-negative strain (P. aeruginosa) killing (84% of dead bacteria), and a promising effect on a Gram-positive strain (S. aureus) eradication (69% of dead bacteria). The fabricated films are promising prototypes for further development of lightweight surfaces with effcient antibacterial action that can be remotely activated on demand

Self-assembled monolayers of copper sulfide nanoparticles on glass as antibacterial coatings

We developed an easy and reproducible synthetic method to graft a monolayer of copper sulfide nanoparticles (CuS NP) on glass and exploited their particular antibacterial features. Samples were fully characterized showing a good stability, a neat photo-thermal effect when irradiated in the Near InfraRed (NIR) region (in the so called \u201cbiological window\u201d), and the ability to release controlled quantities of copper in water. The desired antibacterial activity is thus based on two different mechanisms: (i) slow and sustained copper release from CuS NP-glass samples, (ii) local temperature increase caused by a photo-thermal effect under NIR laser irradiation of CuS NP\u2013glass samples. This behavior allows promising in vivo applications to be foreseen, ensuring a \u201cstatic\u201d antibacterial protection tailored to fight bacterial adhesion in the critical timescale of possible infection and biofilm formation. This can be reinforced, when needed, by a photo-thermal action switchable on demand by an NIR light

Human Serum Albumin Protein Corona in Prussian Blue Nanoparticles.

Prussian Blue nanoparticles (PBnps) are now popular in nanomedicine thanks to the FDA approval of PB. Despite the numerous papers suggesting or describing the in vivo use of PBnps, no studies have been carried out on the formation of a protein corona on the PBnp surface and its stabilizing role. In this paper, we studied qualitatively and quantitatively the corona formed by the most abundant protein of blood, human serum albumin (HSA). Cubic PBnps (41 nm side), prepared in citric acid solution at PB concentration 5 × 10-4 M, readily form a protein corona by redissolving ultracentrifuged PBnp pellets in HSA solutions, with CHSA ranging from 0.025 to 7.0 mg/mL. The basic decomposition of PBnp@HSA was studied in phosphate buffer at the physiological pH value of 7.4. Increased stability with respect to uncoated PBnps was observed at all concentrations, but a minimum CHSA value of 3.0 mg/mL was determined to obtain stability identical to that observed at serum-like HSA concentrations (35-50 mg/mL). Using a modified Lowry protocol, the quantity of firmly bound HSA in the protein corona (hard corona) was determined for all the CHSA used in the PBnp@HSA synthesis, finding increasing quantities with increasing CHSA. In particular, an HSA/PBnp number in the 1500-2300 range was found for CHSA 3.0-7.0 mg/mL, largely exceeding the 180 HSA/PBnp value calculated for an HSA monolayer on a PBnp. Finally, the stabilization brought by the HSA corona allowed us to carry out pH-spectrophotometric titrations on PBnp@HSA in the 3.5-9-0 pH range, revealing a pKa value of 6.68 for the water molecules bound to the Fe3+ centers on the PBnp surface, whose deprotonation is responsible for the blue-shift of the PBnp band from 706 nm (acidic solution) to 685 nm (basic solution)

Modular approach for bimodal antibacterial surfaces combining photo-switchable activity and sustained biocidal release

Photo-responsive antibacterial surfaces combining both on-demand photo-switchable activity and sustained biocidal release were prepared using sequential chemical grafting of nano-objects with different geometries and functions. The multi-layered coating developed incorporates a monolayer of near-infrared active silica-coated gold nanostars (GNS) decorated by silver nanoparticles (AgNP). This modular approach also enables us to unravel static and photo-activated contributions to the overall antibacterial performance of the surfaces, demonstrating a remarkable synergy between these two mechanisms. Complementary microbiological and imaging evaluations on both planktonic and surface-attached bacteria provided new insights on these distinct but cooperative effects