Non-Woven Fabrics Based on Nanocomposite Nylon 6/ZnO Obtained by Ultrasound-Assisted Extrusion for Improved Antimicrobial and Adsorption Methylene Blue Dye Properties.

Approximately 200,000 tons of water contaminated with dyes are discharged into effluents annually, which in addition to infectious diseases constitute problems that afflict the population worldwide. This study evaluated the mechanical properties, surface structure, antimicrobial performance, and methylene blue dye-contaminant adsorption using the non-woven fabrics manufactured by melt-blowing. The non-woven fabrics are composed of nylon 6 (Ny 6) and zinc oxide nanoparticles (ZnO NPs). The polymer nanocomposites were previously fabricated using variable frequency ultrasound assisted-melt-extrusion to be used in melt-blowing. Energy dispersion spectroscopy (SEM-EDS) images showed a homogeneous dispersion of the ZnO nanoparticles in nylon 6. The mechanical properties of the composites increased by adding ZnO compared to the nylon 6 matrix, and sample Ny/ZnO 0.5 showed the best mechanical performance. All fabric samples exhibited antimicrobial activity against S. aureus and fungus C. albicans, and the incorporation of ZnO nanoparticles significantly improved this property compared to pure nylon 6. The absorption efficiency of methylene blue (MB), during 60 min, for the samples Ny/ZnO 0.05 and Ny/ZnO 0.25 wt%, were 93% and 65%, respectively. The adsorption equilibrium data obeyed the Langmuir isotherm.

Preparación de un Adhesivo Sensible a la Presión (PSA) con la Incorporación de Nanopartículas de ZnO. Estudio de sus Propiedades Fisicoquímicas y Antimicrobianas / Preparation of a Pressure Sensitive Adhesive (PSA) with the ZnO Nanoparticles Incorporation. Study of its Physicochemical and Antimicrobial Properties

Resumen Se describe el proceso para obtener un adhesivo sensible a la presión (PSA). Este PSA está formado por un copolímero de acrilato de 2-etilhexil (2-EHA) / metacrilato de metilo (MMA) en una relación 80:20 que se polimerizó mediante una técnica de polimerización en emulsión. Se añadieron nanopartículas de óxido de zinc (NPZnO) a este copolímero, que se sintetizaron previamente y se modificaron superficialmente con 3-aminopropil-3-toxisilano (APTES) y dimetilsulfóxido (DMSO) para mejorar su dispersión en la matriz de copolímero. Los nanocompuestos obtenidos se caracterizaron por espectroscopía infrarroja (FTIR), calorimetría diferencial de barrido (DSC) y pruebas de adhesión al delaminado. Además, se determinó la actividad antimicrobiana contra S. aureus y S. pyogenes, así como la citotoxicidad en células humanas (HeLa). Los resultados demostraron que la adición de las nanopartículas de NPZnO al copolímero incrementa la temperatura de transición vítrea (Tg) así como las propiedades antimicrobianas del adhesivo mejorando a su vez su adhesión superficial. Con respecto al comportamiento adhesivo, el PSA con NPZnO sin modificar mostró una mayor resistencia al delaminado, esto quiere decir que las nanopartículas incrementan la fuerza cohesiva y proporcionan resistencia a temperaturas elevadas, lo cual sería beneficioso a su aplicación final. Finalmente, los resultados de citotoxicidad mostraron que la incorporación de NPZnO al PSA disminuye la viabilidad celular, sin embargo no se considera tóxico acorde a la norma ISO 10993 test for in vitro cytotoxicity.

Abstract The process for obtaining a pressure sensitive adhesive (PSA) is described. This PSA is formed by an acrylate copolymer of 2-ethylhexyl (2-EHA) / methyl methacrylate (MMA) in an 80:20 ratio which was polymerized by emulsion polymerization technique. Zinc oxide nanoparticles (NPZnO) were added to this copolymer, which were previously synthesized, and surface modified with 3-aminopropyltretoxysilane (APTES) and dimethyl sulfoxide (DMSO) to improve its dispersion in the copolymer matrix. The obtained nanocomposites were characterized by infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and T-peel adhesion tests. In addition, the antimicrobial activity against S. aureus and S. pyogenes as well as the cytotoxicity in human cells (HeLa) were determined. The results demonstrated that the ZnO nanoparticles incorporation enhanced the glass transition temperature (Tg) and the antimicrobial activity of PSA copolymer as well as its surface adhesion. It was confirmed that NPZnO modification with APTES increased its antimicrobial activity. Regarding adhesive behavior, PSA with unmodified NPZnO showed a greater peel resistance. This indicates that these nanoparticles enhances the cohesive force and induces a better high temperature performance, which is beneficial for the final application. Finally, cytotoxicity results showed that the incorporation of NPZnO to PSA decreases the cell viability, however this PSA is not toxic according to the standard ISO 10993 test for in vitro cytotoxicity.

Effects of different surface modifying agents on the cytotoxic and antimicrobial properties of ZnO nanoparticles.

Zinc oxide (ZnO) nanoparticles (NPs) have received considerable attention in the medical field because of their antibacterial properties, primarily for killing and reducing the activity of numerous microorganisms. The purpose of this study was to determine whether surface-modified ZnO NPs exhibit different properties compared with unmodified ZnO. The antimicrobial and cytotoxic properties of modified ZnO NPs as well as their effects on inflammatory cytokine production were evaluated. ZnO NPs were prepared using a wet chemical method. Then, the surfaces of these NPs were modified using 3-aminopropyltriethoxysilane (APTES) and dimethyl sulfoxide (DMSO) as modifying agents via a chemical hydrolysis method. According to infrared spectroscopy analysis (FTIR), the structure of the ZnO remained unchanged after modification. Antibacterial assays demonstrated that APTES modification is more effective at inducing an antimicrobial effect against Gram-negative bacteria than against Gram-positive bacteria. Cytotoxicity studies showed that cell viability was dose-dependent; moreover, pristine and APTES-modified ZnO exhibited low cytotoxicity, whereas DMSO-modified ZnO exhibited toxicity even at a low NP concentration. An investigation of inflammatory cytokine production demonstrated that the extent of stimulation was related to the ZnO NP concentration but not to the surface modification, except for IFN-γ and IL-10, which were not detected even at high NP concentrations.

Recombinant adenovirus delivery of calreticulin-ESAT-6 produces an antigen-specific immune response but no protection against a Mycobacterium tuberculosis challenge.

Bacillus Calmette-Guerin (BCG) has failed to efficaciously control the worldwide spread of the disease. New vaccine development targets virulence antigens of Mycobacterium tuberculosis that are deleted in Mycobacterium bovis BCG. Immunization with ESAT-6 and CFP10 provides protection against M. tuberculosis in a murine infection model. Further, previous studies have shown that calreticulin increases the cell-mediated immune responses to antigens. Therefore, to test whether calreticulin enhances the immune response against M. tuberculosis antigens, we fused ESAT-6 to calreticulin and constructed a recombinant replication-deficient adenovirus to express the resulting fusion protein (AdCRT-ESAT-6). The adjuvant effect of calreticulin was assayed by measuring cytokine responses specific to ESAT-6. Recombinant adenovirus expressing the fusion protein produced higher levels of interferon-γ and tumour necrosis factor-α in response to ESAT-6. This immune response was not improved by the addition of CFP-10 to the CRT-ESAT-6 fusion protein (AdCRT-ESAT-6-CFP10). Mice immunized with these recombinant adenoviruses did not decrease the mycobacterial burden after low-dose aerosol infection with M. tuberculosis. We conclude that calreticulin can be used as an adjuvant to enhance the immune response against mycobacterial antigens, but it is not enough to protect against tuberculosis.

Targeting and retention of HPV16 E7 to the endoplasmic reticulum enhances immune tumour protection.

The endoplasmic reticulum (ER) is where the major histocompatibility complex (MHC) class I molecules are loaded with epitopes to cause an immune cellular response. Most of the protein antigens are degraded in the cytoplasm to amino acids and few epitopes reach the ER. Antigen targeting of this organelle by Calreticulin (CRT) fusion avoids this degradation and enhances the immune response. We constructed a recombinant adenovirus to express the E7 antigen with an ER-targeting signal peptide (SP) plus an ER retention signal (KDEL sequence). In cell-culture experiments we demonstrated that this new E7 antigen, SP-E7-KDEL, targeted the ER. Infection of mice with this recombinant adenovirus that expresses SP-E7-KDEL showed interferon induction and tumour-protection response, similar to that provided by an adenovirus expressing the E7 antigen fused to CRT. This work demonstrated that just by adding a SP and the KDEL sequence, antigens can be targeted and retained in the ER with a consequent enhancement of immune response and tumour protection. These results will have significant clinical applications.