Márcio Antônio Fiori

The influence of particle size and AgNO3 concentration in the ionic exchange process on the fungicidal action of antimicrobial glass.

Antimicrobial materials have long been used as an effective means of reducing the risks posed to humans by fungi, bacteria and other microorganisms. These materials are essential in environments where cleanliness, comfort and hygiene are the predominate concerns. This work presents preliminary results for the development of a fungicidal vitreous material that is produced by the incorporation of a silver ionic specimen through ionic exchange reactions. Silver ions were incorporated into powdered glass via ionic exchange in an ionic medium containing silver species with different concentrations of AgNO3. The fungicidal efficiency of the samples was studied as a function of the AgNO3 concentration and the particle size of the glass using the agar diffusion test for the microbiological analysis of the fungus species Candida albicans. The samples were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The experimental results showed that the fungicidal effect was dependent on the AgNO3 concentration in the ionic exchange medium but was not dependent on the particle size of the glass.

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.

Effect of the Temperature in the Antimicrobial Action of the Bactericide Wood Polymer Composite - BWPC

These work present studies about influence of the high temperature at the antimicrobial properties of the Bactericide Wood Polymer Composites (BWPC) after exposition during different times at 110 oC. The composite was formulated containing Polypropylene (PP) as matrix polymeric, wood powder of the species Pinus and Triclosan additive as bactericide agent. The BWPC was exposited during different times in the ambient and submitted to microbiological tests. The Agar Diffusion tests were applied with two kind bacteria, the Echerichia coli (EC - Gram Positive) and Staphylococcus aureos (SA - Gram Negative). The FT-IR and TGA techniques were utilized to available of the temperature effect in the chemical structure of the composites BWPC. The studies showed a strong dependence of the bactericide action of the composites with exposition time at 110 oC and a constant bactericide action after 100 hours of exposition.

Microencapsulation of eugenol molecules by β-cyclodextrine as a thermal protection method of antibacterial action

Eugenol is natural oil that has excellent antibacterial properties but cannot be used to fabricate many products that require thermal processing. One possible alternative to the use of the eugenol molecules in high-temperature processes is the encapsulation of these molecules in a structure that is not toxic and is resistant to thermal treatment. This work investigated the encapsulation process of eugenol molecules in β-cyclodextrine and the antibacterial properties of eugenol-β-cyclodextrine (the eugenol-βCD complex) against Escherichia coli and Staphylococcus aureus. The FTIR, DSC, MEV and TGA results show that the encapsulation method is an excellent alternative to increase the thermal stability of eugenol molecules. A value of 241.32L.mol-1 was determined for the formation constant (Kc) of the eugenol-βCD complex, which confirmed the success of the encapsulation process. The MEV analysis shows the formation of approximately 12μm microcapsules. After the thermal treatment of the eugenol-βCD complex at a temperature of 80°C for 2h, the complex retained significant antibacterial action, which confirms the thermal protection of the eugenol molecules. The minimum inhibitory concentration (MIC) and agar diffusion results show that the microcapsules containing 17.08mmol.L-1 of eugenol exhibited excellent antibacterial action against Escherichia coli and Staphylococcus aureus after thermal treatment.

Effect of the Extrusion Process on the Bactericidal Performance of Biocidal Polypropylene Catheters

This work concerns polypropylene biocidal catheters that incorporate the triclosan molecule. Many studies have applied triclosan as a bactericidal agent in the polymeric matrix but without considering the effect of processing on the biocidal properties. Using the optimal temperature and shear rate during the extrusion process can promote the best microbiological response for a biocidal catheter. Catheters were processed using a linear extruder while systematically varying the triclosan content, processing temperature and screw velocity. A diffusion test in agar and an evaluation of the chemical structure of the polypropylene and triclosan using FTIR were used to characterize the bactericidal properties.

Study of the Processing Conditions Used to Incorporate an Antimicrobial Additive in Thermoplastic Polymer

In the latest years, several studies were realized concerning about the application of biocidal compound in polymers or ceramics, due to the risk offered to human life by the action of pathogenic microorganisms. Many of these materials, considered special, are directed to medical area and to the food industry, for the production of food packaging. Essential oils (EOs) are aromatic liquids obtained from plant material that have bactericidal activities. One example of essential oil is Eugenol, major component of clove oil. Eugenol is the essential oil compound that better reduce the bacterial activities. This work aimed to study the processing conditions used to incorporate an antimicrobial additive in polypropylene in order to find the processing conditions in which the sample obtained have the best bactericidal properties. To evaluate the effect of the processing conditions in the bactericidal action of the compound it was used an statistical experimental factorial planning. The samples obtained underwent microbiological and physical tests to prove its antibactericidal efficiency. The preview results obtained showed significance to some of the studied variables.

Extrusion Effects with Bactericidal Additives in Polymer Wood Composites

Abstract Wood polymer composite is an important material class for industries. Microbiological properties can be an important aspect to enlarge its application base. The biocidal properties of wood polymer composite (WPC) can be aggregated by incorporation of biocidal additives on its composition. But, an important aspect is the evaluation the influence of the fabrication process on its biocidal properties. In particular, the temperature and screw velocity are important parameters for extrusion processes, and the mass proportions of the compounds are important factors to define the WPC properties. Different combinations of process conditions and mass proportions of the composite can promote variation in the magnitude of the bactericidal effect. The bactericidal properties are aggregated in the composite by organic bactericidal additive and the high temperature and high shear rate during the extrusion process can affect the effectiveness of the bactericidal additive function. This paper investigates the effects of the extrusion process parameters associated with different percentages of bactericidal additives on the WPC. The results showed significant effects on the bactericidal properties that depended only on the bactericidal content.

Advances in ultra high molecular weight polyethylene/hydroxyapatite composites for biomedical applications: A brief review

Ultra high molecular weight polyethylene (UHMWPE) is a semicrystalline polymer that has been applied, as a bearing surface in total human joint replacements and artificial bones. UHMWPE has a superior wear resistance, low-friction surface, biological inertness, high levels of strength, creep resistance and low friction coefficient. However, the wear debris generated during the joint motions could cause problem in human implant, such as osteolysis and loosening. For this, several attempts was been made to improve UHMWPE properties and increases safety and biocompatibility in human implants. One of them, include the use of hydroxyapatite (HA), as reinforcement agent to modify the UHMWPE properties and facilitate biological fixation between the implant and the human cells. Recent studies showed that the addition of HA in polymer matrix result in enhancement of mechanical and tribological properties. In addition, it also improves the formation of the actual bond between the material and the living organism since the hydroxyapatite is the major component of the mineral part of the human bone. In this brief review the some properties and characteristic of UHMWPE and HA are described and main processing methods of UHMWPE/HA composites and biocompatibility studies were also reviewed.

Antibacterial and Antifungal Glass with High Biocide Performance: Increased Antimicrobial Efficiency by Acid Activation

A compound contending silver ion specimens presents biocidal properties with effect proportional to ion concentration. An efficient biocidal material can be developed by incorporating silver ions species in glasses by ionic exchange process. The reactive area and material porosity are factors that influence the ion exchange reaction efficiency. Previous studies show that the acid activation of glasses increases the absorption capacity and can also increase the exchange capacity. This paper presents preliminary results on the biocide potencial optimization of the biocide powder glass. This process was performed using hydrochloric acid. Different pH (1.00, 3.00 and 5.00), treatment time (2.0, 4.0 and 6.0 hours) and temperature (30.0, 60.0 and 90.0°C) were used in the samples development. Microbiological analysis of the samples was made by disk diffusion method in the bacteria species Echerichia coli and Staphylococcus aureus. Samples were still submitted to EDS and Atomic Absorption.

Erucamide-Nanoclay Systems Obtained by Intercalation Process

A major challenge in the manufacture of films for polymeric packaging is the definition and setting of the friction coefficient (FCO) for the film surfaces. The FCO values are established with the incorporation of additives during the processing of the polymeric films. But, the homogenization of these additives in the polymeric matrix is very difficult. The additives have different polarity that the matrix polymeric and not are mixable. So, these additives migrate for the surface of the polymeric films easily. Several molecules are used as sliding additives, but among the most efficient are the amides molecules, highlighting the erucamide. This molecule promotes the decrease of the FOC but due its quick migration for the polymeric film surface provides numerous problems for the manufacture of the polymeric packaging and during its application as the product. In this work a nanocomposite (MMT-ERU) was obtained by an intercalation process to improve the compatibility between the polymeric materials and the erucamide molecules. The results shown in this work refers to the studies about the intercalation processes of the erucamide molecules into nanoclays (montmorillonite) to obtain the nanocomposite MMT-ERU. The effect of the temperature and the percentage of the nanoclay in the intercalation processes were studied. The results of x-ray diffraction and differential scanning calorimetry shown that erucamide molecules were intercalated in the nanoclay structures and that intercalation efficiency depends positively of the temperature and percentage amount of the nanoclay in the reaction medium.