Antimicrobial potential of linear low-density polyethylene food packaging with Ag nanoparticles in different carriers (Silica and Hydroxyapatite).

Silver nanoparticles incorporation into polymeric packaging aims to prevent microbiological contamination in food products, thus ensuring superior food safety and preservation. In this context, this study aimed to verify the antimicrobial efficacy of linear low-density polyethylene (LLDPE) films incorporated with silver nanoparticles (AgNPs) dispersed in silica (SiO2) and hydroxyapatite (HAP) carriers at different concentrations. AgNPs + carriers polymer films were characterized at 0.2, 0.4, and 0.6% concentrations using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission gun-scanning electron microscope (FEG-SEM), thermogravimetric analyzer (TGA), differential scanning calorimetry (DSC), and migration in acidic and non-acidic simulants. Antimicrobial action was investigated on Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and the Penicillium expansum and Fusarium solani fungi with antimicrobial activity by direct contact test and bacterial imaging by scanning electron microscopy. AgNPs addition to the LLDPE matrix did not interfere with the films' chemical and thermal properties and presented no significant migration to the external medium. For antimicrobial action, silver nanoparticles showed, in most concentrations, an inhibition percentage higher than 90% on all microorganisms studied, regardless of the carrier. However, a greater inhibitory action on S. aureus and between carriers was found, making hydroxyapatite more effective. The results indicated that nanostructured films with AgNPs + hydroxyapatite showed more promising antimicrobial action on microorganisms than AgNPs + silica, making hydroxyapatite with silver nanoparticle potentially useful in food packaging, improving safety and maintaining quality.

Effect of florfenicol on Piscirickettsia salmonis biofilm formed in materials used in salmonid nets, nylon and high-density polyethylene.

Piscirickettsiosis is the most prevalent bacterial disease affecting seawater salmon in Chilean salmon industry. Antibiotic therapy is the first alternative to counteract infections caused by Piscirickettsia salmonis. The presence of bacterial biofilms on materials commonly used in salmon farming may be critical for understanding the bacterial persistence in the environment. In the present study, the CDC Biofilm Reactor® was used to investigate the effect of sub- and over-MIC of florfenicol on both the pre-formed biofilm and the biofilm formation by P. salmonis under the antibiotic stimuli on Nylon and high-density polyethylene (HDPE) surfaces. This study demonstrated that FLO, at sub- and over-MIC doses, decreases biofilm-embedded live bacteria in the P. salmonis isolates evaluated. However, it was shown that in the P. salmonis Ps007 strain the presence of sub-MIC of FLO reduced its biofilm formation on HDPE surfaces; however, biofilm persists on Nylon surfaces. These results demonstrated that P. salmonis isolates behave differently against FLO and also, depending on the surface materials. Therefore, it remains a challenge to find an effective strategy to control the biofilm formation of P. salmonis, and certainly other marine pathogens that affect the sustainability of the Chilean salmon industry.

Soil presence reduces the control effectiveness of a slow-release formulation of pyriproxyfen on Aedes aegypti (Diptera: Culicidae) larvae.

OBJECTIVE: To assess the influence of soil on the effectiveness of two new slow-release formulations (floating and non-floating) of pyriproxyfen coextruded with low-density polyethylene. METHODS: Two slow-release devices were developed using low-density polyethylene, pyriproxyfen as larvicide and calcium carbonate as filler. A factorial design was used to evaluate the effect of soil presence on the performance of each device. Weekly bioassays were performed. RESULTS: Soil presence affected treatment effectiveness, but this effect was associated with device type. The tablets were effective for nearly 3 months. CONCLUSION: Treatment effectiveness could be reduced because of the loss of pyriproxyfen by several physico-chemical processes such as adsorption into the soil.

OBJECTIF: Evaluer l'influence de la terre sur l'efficacité de deux nouvelles formulations à libération lente (flottante et non flottante) de pyriproxyfène coextrudé avec du polyéthylène de faible densité. MÉTHODES: Deux dispositifs à libération lente ont été développés en utilisant du polyéthylène de faible densité, du pyriproxyfène comme larvicide et du carbonate de calcium comme agent de charge. Un plan factoriel a été utilisé pour évaluer l'effet de la présence de terre sur les performances de chaque dispositif. Des essais biologiques hebdomadaires ont été effectués. RÉSULTATS: La présence de terre a affecté l'efficacité du traitement, mais cet effet était associé au type de dispositif. Les comprimés ont été efficaces pendant près de 3 mois. CONCLUSION: L'efficacité du traitement pourrait être réduite en raison de la perte du pyriproxyfène par plusieurs processus physicochimiques tels que l'adsorption sur la terre.

Tissue response to porous high density polyethylene as a three-dimensional scaffold for bone tissue engineering: An experimental study.

High density polyethylene (HDPE) is a synthetic biomaterial used as a three-dimensional scaffold for bone defect reconstruction. Reports differ with regard to its biological response, particularly its osteoconductive capacity. The aim of the present work was to histologically and histomorphometrically evaluate tissue response to porous HDPE. An in vivo study was conducted in rat tibia to evaluate osteogenic capacity, angiogenesis, inflammatory response, and the presence of multinucleated giant cells 14 and 60 days post-biomaterial implantation. Histological examination 14 days post-implantation showed fibrovascular tissue inside pores and on the surface of porous HDPE, acute inflammatory response, scant multinucleated giant cells (MNGCs), and lamellar bone in contact with the biomaterial. An increase in the proportion of lamellar bone tissue, no inflammatory response, and a decrease in the number of MNGCs were observed at 60 days. The histomorphometric study showed a significant time-dependent increase both in the area of bone tissue formed in contact with the porous HDPE (14d: 24.450 ± 11.623 µm2 vs. 60d: 77.104 ± 26.217 µm2, p < 0.05) and in the percentage of bone tissue in contact with the porous HDPE (osseointegration). A significant decrease in the number of MNGCs was also observed at 60 days post-implantation. Porous HDPE showed adequate osteoconductive properties, and only caused an initial inflammatory response. Although this biomaterial has traditionally been used juxtaosseoulsy, its adequate osteoconductive properties broaden the scope of its application to include intraosseous placement.

Application of glass particles doped by Zn(+2) as an antimicrobial and atoxic compound in LLDPE and HDPE.

This study demonstrates the potential application of glass particles doped with Zn(+2) (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00wt.% and at a time of 4h, the bactericidal performance is excellent and equal for both polymeric compounds.

Avaliação microscópica da reação tecidual em subcutâneo de rato frente a cimentos Portland contendo diferentes concentrações de arsênico / Microscopic evaluation of the tissue reaction in subcutaneous of rats to Portland cements containing different arsenic concentrations

O MTA (Agregado Trióxido Mineral) tem sido utilizado na endodontia com diferentes finalidades terapêuticas. Essencialmente ele é constituído pelo cimento Portland acrescido de um radiopacificador. Entre seus componentes, é destacada a presença do arsênico, o qual sofre variação de concentração em função da origem do calcário. A dúvida é que se diferentes concentrações de arsênico representam alguma influência na sua biocompatibilidade. O objetivo deste estudo foi avaliar, microscopicamente, a reação tecidual em subcutâneo de ratos frente a cimentos Portland contendo diferentes concentrações de arsênico. Foram utilizados 36 ratos Wistar albinos, distribuídos em 4 grupos experimentais segundo o material empregado perfazendo um total de 6 implantes por período (15, 30 e 60 dias). A lateral dos tubos serviram como grupo controle. Após 15, 30 e 60 dias, os animais foram mortos e os espécimes foram preparados histotecnicamente para análise microscópica. Os dados da avaliação morfométrica foram submetidos à análise de variância a dois critérios (ANOVA) e teste de Tukey para a comparação (p<0,05). Os resultados mostraram uma maior densidade de volume de células inflamatórias aos 15 dias, com redução dessa densidade com o passar do tempo para todos os materiais. Os resultados da análise descritiva mostraram inflamação crônica induzida pelos materiais, com intensidade de leve a moderada, e organização de uma cápsula fibrosa ao redor de todos os espécimes e em todos os períodos. Os cimentos analisados produziram respostas inflamatórias semelhantes, mesmo apresentando quantidades diferentes de arsênico na composição, apenas com diferença estatisticamente significante entre o cimento Portland cinza Votoran e os demais cimentos nos três períodos estudados.Título em inglêsMicroscopic evaluation of the tissue reaction in subcutaneous of rats to Portland cements containing different.

The MTA (Mineral Trioxide Aggregate) has been used in Endodontics for different therapeutic purposes. Essentially, it is composed of Portland cement with addition of a radiopacifier. Its components include arsenic, whose concentration is variable according to the origin of the calcareous. There is doubt whether different arsenic concentrations might influence its biocompatibility. This microscopic study evaluated the reaction of subcutaneous tissue of rats to Portland cements containing different arsenic concentrations. The study was conducted on 36 albinus Wistar rats, divided in 12 animals for each study group. Each animal received two implants of polyethylene tubes, completely filled with the test cements, and the lateral aspect of the tubes was taken as control group. The animals were killed after 15, 30 and 60 days and the specimens were submitted to histotechnical preparation for microscopic analysis. Data of the morphometric analysis were submitted to two-way analysis of variance (ANOVA) and the Tukey test for comparison (p<0.05). The results evidenced greater density of volume of inflammatory cells at 15 days, which was reduced with time for all materials. The results of this descriptive analysis demonstrated chronic inflammation induced by the materials, of mild to moderate intensity, and organization of a fibrous capsule around all specimens and in all periods. The cements induced similar tissue responses, despite the different arsenic concentrations in their composition.

Evaluation of alveolar socket response to Angelus MTA and experimental light-cure MTA.

OBJECTIVE: The aim of this study was to evaluate the rat alveolar socket response to implanted polyethylene tubes filled with a light-cured MTA or Angelus MTA. STUDY DESIGN: Fifty-seven Wistar rats received an implant filled with one of the materials in the dental socket of the right central incisor. After 30, 60, and 90 days, animals were killed, and the right hemimaxillas were removed and processed to be analyzed on light microscopy. After embedding in paraffin, 6-µm-thick sections were obtained and stained with hematoxylin and eosin. Qualitative and quantitative analyses of the reaction were performed. RESULTS: It was observed that the light-cured MTA presented a similar response compared with Angelus MTA, characterized by the reduction of the chronic inflammatory response and organization of the alveolar bone close to the materials, especially at the 90th day of observation. CONCLUSIONS: It was concluded that both materials were well accepted by the alveolar tissue of rats, with the formation of mineralized tissue close to the materials.

Evaluation of subcutaneous and alveolar implantation surgical sites in the study of the biological properties of root-end filling endodontic materials.

OBJECTIVE: The aim of this study was to compare two methodologies used in the evaluation of tissue response to root-end filling materials in rats. MATERIAL AND METHODS: Forty rats were divided into 4 groups: in Groups I and II (control groups), empty polyethylene tubes were implanted in the extraction site and in the subcutaneous tissue, respectively; in Groups III and IV, polyethylene tubes filled with ProRoot MTA were implanted in the extraction site and in the subcutaneous tissue, respectively. The animals were killed 7 and 30 days after tube implantation, and the hemi-maxillas and the capsular subcutaneous tissue, both with the tubes, were removed. Specimens were processed and evaluated histomorphologicaly under light microscopy. The scores obtained were analyzed statistically by the Kruskal-Wallis test (p<0.05). RESULTS: There were no statistically significant differences between the implantation methods (p=0.78033, p=0.72039). It was observed that the 30-day groups presented a more mature healing process due to smaller number of inflammatory cells. CONCLUSIONS: The present study showed no differences in tissue responses as far as the implantation site and the studied period were concerned. Alveolar socket implantation methodology represents an interesting method in the study of the biological properties of root-end filling endodontic materials due to the opportunity to evaluate bone tissue response.

Evaluation of subcutaneous and alveolar implantation surgical sites in the study of the biological properties of root-end filling endodontic materials

OBJECTIVE: The aim of this study was to compare two methodologies used in the evaluation of tissue response to root-end filling materials in rats. MATERIAL AND METHODS: Forty rats were divided into 4 groups: in Groups I and II (control groups), empty polyethylene tubes were implanted in the extraction site and in the subcutaneous tissue, respectively; in Groups III and IV, polyethylene tubes filled with ProRoot MTA were implanted in the extraction site and in the subcutaneous tissue, respectively. The animals were killed 7 and 30 days after tube implantation, and the hemi-maxillas and the capsular subcutaneous tissue, both with the tubes, were removed. Specimens were processed and evaluated histomorphologicaly under light microscopy. The scores obtained were analyzed statistically by the Kruskal-Wallis test (p<0.05). RESULTS: There were no statistically significant differences between the implantation methods (p=0.78033, p=0.72039). It was observed that the 30-day groups presented a more mature healing process due to smaller number of inflammatory cells. CONCLUSIONS: The present study showed no differences in tissue responses as far as the implantation site and the studied period were concerned. Alveolar socket implantation methodology represents an interesting method in the study of the biological properties of root-end filling endodontic materials due to the opportunity to evaluate bone tissue response.

Cyclodextrin-functionalized biomaterials loaded with miconazole prevent Candida albicans biofilm formation in vitro.

Polyethylene (PE) and polypropylene (PP) were functionalized at their surfaces with cyclodextrins (CDs) in order to prevent the adhesion and proliferation of Candida albicans on medical devices made from these polymers. The surface functionalization involved the grafting of glycidyl methacrylate (GMA) after oxidative gamma-ray pre-irradiation, followed by the attachment of beta-CD and HP-beta-CD to PE-g-GMA and PP-g-GMA surfaces. The yield of CD functionalization directly depended on the amount of GMA grafted. The presence of CDs on the surface of the polymers did not compromise their cell compatibility, but remarkably changed their protein adsorption profile. In contrast to unmodified PE and PP that adsorb significant amounts of fibrinogen ( approximately 0.047 mg cm(-2)) but not albumin, the CD-modified polyethers promoted the adsorption of albumin (between 0.015 and 0.155 mg cm(-2)) and reduced the adsorption of fibrinogen. Furthermore, functionalization with CDs provided PE and PP with the capability to incorporate the anti-fungal drug miconazole (up to 0.27 mg cm(-2)), leading to reduced biofilm formation by C. albicans in an in vitro biofilm model system. Overall, the results of the work indicate that the novel approach for functionalization of PE and PP is potentially useful to reduce the likelihood of foreign body-related infections.

Bacterial immobilization by adhesion onto agave-fiber/polymer foamed composites.

Adhesion of Pseudomonas putida F1 onto agave-fiber/recycled-polyethylene foamed composites was studied under different controlled conditions. The adhesion process was analyzed in batch experiments controlling factors such as pH, contact time, temperature, initial biomass concentration and ionic strength; and was verified by scanning electron microscopy (SEM). The number of adhered bacteria after the experimental time was determined by difference between concentration of suspended cells in NaCl solution contained in two different Erlenmeyer flasks, one of the flasks with composite pellets and the other one without them. The concentration of cells in each flask was obtained using the serial dilution technique. Experimental data analysis showed that adsorption follows first-order kinetics. And it was further corroborated to be an irreversible process. For the first time, an equation is proposed here to predict the correlation between adhered bacteria and aqueous pH. In addition to the obvious reuse of waste material, these results suggested that agave-fiber/polymer foamed composites could be used as support for bacterial immobilization to be applied, among others in environmental processes such as bioremediation and biofiltration of gases with almost limitless possibilities.

Digital image processing for biocompatibility studies of clinical implant materials.

The use of computer vision coupled with scanning electron microscopy (SEM) was used to monitor the platelet adhesion and activation onto blood-contacting materials. The interaction of blood platelets with polyethylene (PE), poly(ethylene terephthalate) (PET), and poly(vinylchloride) (PVC) after contact of the polymeric surfaces with whole blood was studied. The SEM images (SEM Phillips XL 30) were captured using HLImage++ computer vision systems. A library with a considerable number of acceptance or rejection of samples has been conceived and implemented. The obtained results make the developed computational vision system a promising tool for the evaluation of blood compatibility of biomaterials.