Solvent-assisted in situ synthesis of cysteamine-capped silver nanoparticles

Silver nanoparticles offer a huge potential for biomedical applications owing to their exceptional properties and small size. Specifically, cysteamine-capped silver nanoparticles could form the basis for new anticancer therapies combining the cytotoxic effect of the silver core with the inherent antitumor activity of cysteamine, which inhibit cancer cell proliferation and suppress invasion and metastasis. In addition, the capability of the cysteamine coating monolayer to couple a variety of active principles and targeting (bio)molecules of interest proves key to the tailoring of this platform in order to exploit the pathophysiology of specific tumor types. Nevertheless, the chain length and conformational flexibility of cysteamine, together with its ability to attach to the surface of silver nanoparticles via both the thiol and the amine group, have made the in situ synthesis of these particles an especially challenging task. Herein we report a solvent-assisted in situ synthesis method that solves this problem. The obtained nanoparticles have been fully characterized by UV–visible absorption spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, electron diffraction measurement, high resolution transmission electron microscopy, scanning transmission electron microscopy, energy dispersive x-ray spectroscopy nanoanalysis, and dynamic light scattering measurement. Our synthesis method achieves extremely high yield and surface coating ratio, and colloidal stability over a wide range of pH values including physiological pH. Additionally, we have demonstrated that cysteamine-capped nanoparticles obtained by this method can be conjugated to an antibody for active targeting of the epidermal growth factor receptor, which plays an important role in the pathogenesis and progression of a wide variety of tumors, and induce cell death in human squamous carcinoma cells. We believe this method can be readily extended to combinations of noble metals and longer chain primary, secondary, ternary or even quaternary aminethiolsEspaña, Junta de Andalucía P10- FQM-6615España, Ministerio de Economia y Competitividad CTP2016-80206-

Assessment of nanoparticles/nanocomposites to inhibit micro-algal fouling on limestone façades.

Proyecto Art-Risk, BIA2015-64878-RThis study conducted a comparison between biocide treatments based on nanoparticles of silver, copper, ZnO, TiO2 and silver/ TiO2 nanocomposites to analyse their capability to inhibit microalgal fouling on stone buildings. Biofouling is one of the main alterations on stone façades, causes degradation of their constituent materials and interferes with their aesthetic values. The proposed treatments were tested on a limestone from the historic quarry of Estepa (Spain), widely used as construction material in the South of Spain. The applicability of the treatments was evaluated by colorimetry. The biocidal effectiveness of the nanoparticles was studied on stone surfaces by multispectral imaging, digital image analysis and optical coherence tomography. This is a low-cost and efficient protocol to validate biocidal treatments for limestone monuments, and our results demonstrate the potential of silver and ZnO nanoparticles as a protective treatment for stone façades. The results have implications for practitioners working on historic buildings.Department of Physical, Chemical and Natural Systems, Pablo de Olavide UniversityDepartment of Management and Conservation of Ecclesiastical Cultural Heritage Objects, University Ecclesiastical Academy of ThessalonikiPreprin

PEGylated versus non-PEGylated magnetic nanoparticles as camptothecin delivery system

Camptothecin (CPT; (S)-(+)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione) is a highly cytotoxic natural alkaloid that has not yet found use as chemotherapeutic agent due to its poor water-solubility and chemical instability and, as a consequence, no effective administration means have been designed. In this work, camptothecin has been successfully loaded into iron oxide superparamagnetic nanoparticles with an average size of 14 nm. It was found that surface modification of the nanoparticles by polyethylene glycol enables loading a large amount of camptothecin. While the unloaded nanoparticles do not induce apoptosis in the H460 lung cancer cell line, the camptothecin-loaded nanoparticle formulations exhibit remarkable pro-apoptotic activity. These results indicate that camptothecin retains its biological activity after loading onto the magnetic nanoparticles. The proposed materials represent novel materials based on naturally occurring bioactive molecules loaded onto nanoparticles to be used as chemotherapeutic formulations. The procedure seems apt to be extended to other active molecules extracted from natural products. In addition, these materials offer the potential of being further implemented for combined imaging and therapeutics, as magnetic nanoparticles are known to be multifunctional tools for biomedicine

Exploiting the π\pi-bonding for the separation of benzene and cyclohexane in zeolites

Separation of benzene and cyclohexane is one of the greatest challenges in industry. Their close boiling points and similar properties make them difficult compounds to separate. In this context, adsorption-based separation using zeolites or aluminosilicates is a promising technology. In the present work, we combine experimental measurements, density functional theory, and classical simulations to study the targeted separation. We analyse the effect of the sodium content in the adsorption of benzene and cyclohexane in three zeolites with FAU topology; high silica FAU, NaY and NaX. Quasi-equilibrated temperature adsorption and desorption measurements, first principles calculations, and classical simulations reveal the strong interaction between benzene molecules and sodium cations present in aluminosilicates and identify this fact as the key factor for the separation. We have developed a set of parameters to study the targeted separation by fitting to the experimental values and have run Monte Carlo simulations in the Grand-Canonical ensemble to obtain the adsorption isotherms and isobars. In addition, we have performed density functional theory calculations to analyse the specific interaction between benzene or cyclohexane and extra-framework sodium cations. Our results show that NaY and NaX zeolites are able to separate these compounds with extremely high efficiency

EGFR-targeting antitumor therapy: Neuregulins or antibodies?

Malignancies such as lung, breast and pancreatic carcinomas are associated with increased expression of the epidermal growth factor receptor, EGFR, and its role in the pathogenesis and progression of tumors has made this receptor a prime target in the development of antitumor therapies. In therapies targeting EGFR, the development of resistance owing to mutations and single nucleotide polymorphisms, and the expression of the receptor ligands themselves are very serious issues. In this work, both the ligand neuregulin and a bispecific antibody fragment to EGFR are conjugated separately or together to the same drug-delivery system to find the most promising candidate. Camptothecin is used as a model chemotherapeutic drug and superparamagnetic iron oxide nanoparticles as a delivery system. Results show that the lowest LD50 is achieved by formulations conjugated to both the antibody and the ligand, demonstrating a synergy. Additionally, the ligand location in the nucleus favors the antitumor activity of Camptothecin. The high loading capacity and efficiency convert these systems into a good alternative for administering Camptothecin, a drug whose use is otherwise severely limited by its chemical instability and poor solubility. Our choice of targeting agents allows treating tumors that express ErbB2 (Her2+ tumors) as well as Her2- tumors expressing EGFR.The authors acknowledge Junta de Andalucía and Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea). This work was partially supported by Junta de Andalucía (Proyecto de Investigación de Excelencia P10-FQM-6615 and PAIDI FQM-319)