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The CO2 reduction by solar means has been discussed as an alternative to emission abatement, a fundamental topic for sustainable, carbon-free production in the future. However, the choice of efficient systems, starting with the catalysts, is still a critical issue, especially due to the poor activity of available options. Polyoxometalates have been extensively studied as promising photocatalysts due to their semiconducting properties. Nevertheless, the synthetic conditions of polyoxoniobate are stringent due to the low reaction activity of Nb species, the lack of soluble precursors, and the narrow pH range. Unlike the literature, in the present study, we report a simple polyoxoniobate synthesis method. This synthesis method has some remarkable features, such as low processing time and temperature and good activity and selectivity in the CO2 photoreduction process. The results revealed an outstanding efficiency for the CO2 reduction reaction with a high selectivity of CO2 to CO conversion (92.5%). Furthermore, C2 compounds (e.g., acetate) were produced in the liquid phase of the reaction system. Our findings are significant for indicating the potential of polyoxoniobate for CO2 photoreduction, which opens a way to control competitive reactions with synthesis, leading to higher selectivity.

Eggs are an important, low-cost, high-protein food with a balanced nutritional composition. The sanitary quality of commercial eggs is a bottleneck that needs to be overcome through the use of technologies that guarantee the safety of the product. This work aimed to prepare, characterize, and evaluate the coating of commercial eggs by chitosan filmogenic solutions and 1st- and 5th-generation quaternary ammonium salt components (QACs). Egg shell properties such as thickness, morphology, and wettability were analyzed by scanning electron microscopy (SEM),TG/DSC, pHPZC, contact angle, color, and weight loss. Determinations of the minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) with Salmonella spp., Escherichia coli, and Staphylococcus aureus were performed, as well as proliferation tests on eggshell surfaces. The results show a synergistic effect of the biopolymer in terms of antibacterial activity against all microorganisms tested. The composite of chitosan and ammonium quaternary ammonium films offers physical and biological safety to guarantee the integrity and microbiological quality of commercial eggs. Egg coating using bioactive chitosan films was shown to be a suitable method of preservation and a physical and microbiological barrier to minimize egg quality loss during storage, as well as to increase shelf life. Graphical abstract

Made available in DSpace on 2022-04-28T19:47:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Infected cutaneous ulcers from diabetic rats with Candida albicans and Streptococcus aureus were treated with spray formulations containing green silver nanoparticles (GS), chemical silver nanoparticles (CS), or pomegranate peel extract (PS). After wound development and infection, the treatments were performed twice per day for 14 days. The wound healing was analyzed on days 2, 7, and 14 through the determination of CFUs, inflammatory infiltrate, angiogenesis, fibroplasia, myeloperoxidase, and collagen determination. Expressive improvement in wound healing was noted using both silver nanoparticles for 7 days. All the treatments were superior to controls and promoted significant S. aureus reduction after 14 days. CS presented better anti-inflammatory results, and GS and CS the highest number of fibroblasts. Despite the techniques’ limitations, GS and CS demonstrated considerable potential for managing infected wounds, especially considering no early strategies prior to the drugs, such as the debridement of these wounds, were included. Department of Dental Materials and Prosthodontics School of Dentistry São Paulo State University (UNESP) Laboratory of Research Development & Innovation Apis Flora Industrial e Comercial Ltda Department of Chemistry Federal University of São Carlos Department of Dental Materials and Prosthodontics School of Dentistry São Paulo State University (UNESP) FAPESP: 2016/04230-9

The aim of this study were to produce a multifunctional nanocomposite combining silver nanoaparticles (Ag), sodium trimetaphosphate (TMP) and fluoride (F), to investigate its effect on dental enamel demineralization and on biofilms of Streptococcus mutans and Candida albicans.Bovine enamel blocks were submitted to five pH cycles and treated 2x/day with 100 ppm F, 225 ppm F, 100 ppm F + 0.2%TMP or 100 ppm F + 0.2%TMP+10% Ag (100F/TMP/Ag). Next, surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), enamel fluoride (F) and calcium (Ca) concentration were determined. Biofilms from single and dual species of S. mutans and C. albicans were treated with 100F/TMP/Ag, Ag or chlorhexidine gluconate for 24 h. The antibiofilm effect was evaluated by colony-forming unit counting and Scanning Electron Microscopy.The nanocomposite reduced 43.0% of %SH and was similar with samples treated with 225F, 100F/TMP and 100/TMP/Ag. The attribute of F and/or TMP in reducing ΔKHN in 5-20 μm was not affected by the addiction of Ag (110F = 225F = 100F/TMP = 100F/TMP/AgNegative Control). Further, 100F/TMP/Ag strongly reduced viable cells of S. mutans in dual biofilms (∼5 logThe 100F/TMP/F promoted a protective effect against enamel demineralization and was able to significantly inhibit the growth of biofilms of S. mutans and C. albicans.The focus on prevention and non-invasive dental treatment is the most effective and least costly way to improve the population's oral health conditions. We present a nanocomposite for a multiple approach in prevention of caries.

Metals capped with organochalcogenides have attracted considerable interest due to their practical applications, which include catalysis, sensing, and biosensing, due to their optical, magnetic, electrochemical, adhesive, lubrication, and antibacterial properties. There are numerous reports of metals capped with organothiol molecules; however, there are few studies on metals capped with organoselenium or organotellurium. Thus, there is a gap to be filled regarding the properties of organochalcogenide systems which can be improved by replacing sulfur with selenium or tellurium. In the last decade, there has been significant development in the synthesis of selenium and tellurium compounds; however, it is difficult to find commercial applications of these compounds because there are few studies showing the feasibility of their synthesis and their advantages compared to organothiol compounds. Stability against oxidation by molecular oxygen under ambient conditions is one of the properties which can be improved by choosing the correct organochalcogenide; this can confer important advantages for many more suitable applications. This paper reports the successful synthesis and characterization of gold nanoparticles functionalized with organochalcogenide molecules (dibutyl-disulfide, dibutyl-diselenide and dibutyl-ditelluride) and evaluates the oxidation stability of the organochalcogenides. Spherical gold nanoparticles with diameters of 24 nm were capped with organochalcogenides and were investigated using X-ray photoelectron spectroscopy (XPS) to show the improved stability of organoselenium compared with organothiol and organotellurium. The results suggest that the organoselenium is a promising candidate to replace organothiol because of its enhanced stability towards oxidation by molecular oxygen under ambient conditions and its slow oxidation rate. The observed difference in the oxidation processes, as discussed, is also in agreement with theoretical calculations.

Made available in DSpace on 2019-10-06T16:09:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objective: To evaluate the effect of a fluoride toothpaste containing nano-sized sodium hexametaphosphate (HMPnano) on enamel demineralization on the biochemical composition and insoluble extracellular polysaccharide (EPS) in biofilm formed in situ. Methods: This crossover double-blind study consisted of four phases (7 days each), in which 12 volunteers wore intraoral appliances containing four enamel bovine blocks. The cariogenic challenge was performed using 30% sucrose solution (6×/day). Blocks were treated 3×/day with the following toothpastes: no F/HMP/HMPnano (Placebo), conventional fluoride toothpaste, 1100 ppm F (1100F), 1100F + 0.5% micrometric HMP (1100F/HMP), and 1100F + 0.5% nano-sized HMP (1100F/HMPnano). The percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), and enamel calcium (Ca), phosphorus (P), and fluoride (F) were determined. Moreover, biofilms formed on the blocks were analyzed for F, Ca, P, and insoluble extracellular polysaccharide (EPS) concentrations. Data were analyzed using one-way ANOVA, followed by Student–Newman–Keuls’ test (p < 0.001). Results: 1100F/HMPnano promoted the lowest %SH and ΔKHN among all groups (p < 0.001). The addition of HMPnano to 1100F significantly increased Ca concentrations (p < 0.001). The 1100F/HMPnano promoted lower values of EPS when compared with 1100F (~ 70%) (p < 0.001) and higher values of fluoride and calcium in the biofilms (p < 0.001). Conclusion: 1100F/HMPnano demonstrated a greater protective effect against enamel demineralization and on the composition of biofilm in situ when compared to 1100F toothpaste. Clinical relevance: This toothpaste could be a viable alternative to patients at high risk of caries. School of Dentistry Araçatuba Department of Pediatric Dentistry and Public Health São Paulo State University (UNESP), Rua José Bonifácio 1193 LIEC-Department of Chemistry Federal University of São Carlos (UFSCar) School of Dentistry Araçatuba Department of Pediatric Dentistry and Public Health São Paulo State University (UNESP), Rua José Bonifácio 1193 FAPESP: 2016/03148-7

Made available in DSpace on 2021-06-25T10:33:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Background: Although silver nanoparticles (SNP) have proven antimicrobial activity against different types of microorganisms, the effect of SNP incorporation into acrylic resin to control Candida albicans biofilm formation aiming at the prevention of Candida-associated denture stomatitis has not yet been fully elucidated. Objectives: This study aimed to evaluate the antimicrobial effect of an acrylic resin containing SNP on C. albicans biofilm growth, the flexural strength of this material and tissue reaction in the subcutaneous connective tissue of rats to SNP. Method: SNP were synthesized through silver nitrate reduction by sodium citrate. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to verify the size and colloidal stability. SNP were added to acrylic resin monomer (Lucitone 550) at 0.05, 0.5 and 5 vol%. The antimicrobial effect against C. albicans (ATCC 10231) was investigated by the enumeration of colony-forming units (CFUs) and SEM. The three-point bending test was performed to analyze the flexural strength. Tissue reaction was evaluated after 7 and 60 days of implantation in the connective tissue of Wistar rats. Results: Spherical particles of 5 and 10 nm were obtained. SNP at 0.05 and 0.5% incorporated into acrylic resin was effective in reducing C. albicans biofilm growth (p < .001). SEM revealed that the material was able to disrupt C. albicans biofilm formation and did not reduce the flexural strength compared to control (p > .05). The inflammatory response observed 60 days after implantation SNP in the subcutaneous tissue was similar to control. Conclusion: It was concluded that SNP addition at 0.05 and 0.5% into acrylic resin exhibited antimicrobial effects against C. albicans biofilm, did not interfere in the flexural strength and may be considered biocompatible. Department of Diagnosis and Surgery Araçatuba Dental School Univ Estadual Paulista - UNESP Department of Pediatric Dentistry and Public Health Dental Araçatuba Dental School Univ Estadual Paulista - UNESP LIEC-Department of Chemistry Federal University of São Carlos - UFSCar Department of Dental Materials and Prosthodontics Ribeirão Preto Dental School São Paulo State University Department of Endodontics Araçatuba Dental School Univ Estadual Paulista – UNESP Department of Basic Sciences Araçatuba Dental School Univ Estadual Paulista – UNESP Department of Dental Materials and Prosthodontics Araçatuba Dental School Univ Estadual Paulista – UNESP Department of Diagnosis and Surgery Araçatuba Dental School Univ Estadual Paulista - UNESP Department of Pediatric Dentistry and Public Health Dental Araçatuba Dental School Univ Estadual Paulista - UNESP Department of Dental Materials and Prosthodontics Ribeirão Preto Dental School São Paulo State University Department of Endodontics Araçatuba Dental School Univ Estadual Paulista – UNESP Department of Basic Sciences Araçatuba Dental School Univ Estadual Paulista – UNESP Department of Dental Materials and Prosthodontics Araçatuba Dental School Univ Estadual Paulista – UNESP FAPESP: 2010/05788-7 CNPq: 577163/2008-6

A new electrode for the photoelectrochemical removal of 17β-estradiol from water using ruthenium oxide nanoparticles supported on reduced graphene oxide is proposed in this study. The morphology, microstructure and the electrochemical performance of the material were characterized using HRTEM, XRD and Raman spectroscopy. The characterization showed the formation of reduced graphene oxide from a micro-wave assisted hydrothermal method with a particle size of 5.0 nm + 2.4 nm. The electrochemical measurements point to a high performance of the electrode in the presence of a white light source. The hormone removal efficiency in water containing 50 μmol L−1 of 17β-estradiol was evaluated using chronoamperometry at +1.0 V and the process was monitored using liquid chromatography. The reaction is pseudo first order with the removal of 92.2% of 17β-estradiol after 60 min of photoelectrocatalytic treatment.

Bismuth titanate with sillenite structure (Bi 12 TiO 20 ) was prepared at lower temperatures and shorter times using a modified oxidant peroxide method (OPM). Bi 12 TiO 20 was synthesized utilizing commercial Bi 2 O 3 and reactive titanium dioxide nanoparticles having peroxo-modified surfaces. Rather than depending on particle size, the reaction mechanism is related to the highly exothermic decomposition of peroxo groups, regardless the titanium source used, which locally releases a large amount of energy that can accelerate the reaction, similar to self-propagating high temperature routes (SHS).

Self-assembly of nanoparticles on living biotemplate surfaces is a promising route to fabricate nano- or microstructured materials with high efficiency and efficacy. We used filamentous fungi to fabricate microtubules of gold nanoparticles through a novel approach that consists of isolating the hyphal growth from the nanoparticle media. This improved methodology resulted in better morphological control and faster adsorption kinetics, which reduced the time needed to form homogeneous microtubules and allowed for control of microtubule thickness through successive additions of nanoparticles. Differences in the adsorption rates due to modifications in the chemical identity of colloidal gold nanoparticles indicated the influence of secondary metabolites and growth media in the fungi metabolism, which demonstrated the need to choose not only the fungus biotemplate but also the correct medium to obtain microtubules with superior properties.

Made available in DSpace on 2018-11-26T16:40:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Introduction: Silver nanoparticles have been used for different purposes in dentistry, including endodontic treatments. The aim of this study was to determine the cytotoxicity of different types of silver nanoparticles on mouse fibroblast cell line L929 and the reaction of subcutaneous connective tissue of Wistar rats to these nanoparticles. Methods: Silver nanoparticles of an average size of 5 nm were synthesized with ammonia (SNA) or polyvinylpyrrolidone (SNP). L929 was exposed to SNA and SNP (0.1-100 mu g/mL), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and enzyme-linked immunosorbent assays were performed after 6, 24, and 48 hours. Culture medium was used as the control. Sixteen rats received, individually, 3 polyethylene tubes filled with a fibrin sponge embedded in 100 mu L SNA or SNP (1 mu g/mL). A fibrin sponge with no embedding was the control. Tissue reaction was performed qualitatively and quantitatively after 7, 15, 30, and 90 days of implantation in the dorsal connective tissue of Wistar rats. Results: SNA and SNP were cytotoxic to L929 in higher concentrations, with SNA significantly more toxic than SNP. SNA and SNP did not induce significant interleukin-1 beta and interleukin-6 production. The release of stern cell factor by L929 increased 48 hours after the treatment with SNP at 5 mu g/rnL. Histologic examination showed that the inflammatory responses caused by SNA and SNP at 1 mu g/mL were similar to the control in all experimental periods. Conclusions: It was concluded that SNA and SNP were not cytotoxic at 25 mu g/mL or lower concentrations. However, for safe clinical use, further studies establishing others points of its toxicologic profile are recommended. Univ Estadual Paulista, Aracatuba Dent Sch, Dept Pediat Dent & Publ Hlth Dent, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Pathol & Clin Propedeut, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Basic Sci, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Endodont, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Dent Mat & Prosthodont, Aracatuba, SP, Brazil Univ Fed Sao Carlos, Dept Chem, Interdisciplinary Lab Electrochem & Ceram, BR-13560 Sao Carlos, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Pediat Dent & Publ Hlth Dent, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Pathol & Clin Propedeut, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Basic Sci, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Endodont, Aracatuba, SP, Brazil Univ Estadual Paulista, Aracatuba Dent Sch, Dept Dent Mat & Prosthodont, Aracatuba, SP, Brazil FAPESP: 2013/07296-2 FAPESP: 2010/05788-7

Nanobiomaterials combining remineralization and antimicrobial abilities would bring important benefits to control dental caries. This study aimed to produce nanocompounds containing calcium glycerophosphate (CaGP) and silver nanoparticles (AgNP) by varying the reducing agent of silver nitrate (sodium borohydride (B) or sodium citrate (C)), the concentration of silver (1% or 10%), and the CaGP forms (nano or commercial), and analyze its characterization and antimicrobial activity against ATCC Candida albicans (10231) and Streptococcus mutans (25175) by the microdilution method. Controls of AgNP were produced and silver ions (Ag+) were quantified in all of the samples. X-ray diffraction, UV-Vis, and scanning electron microscopy (SEM) analysis demonstrated AgNP associated with CaGP. Ag+ ions were considerably higher in AgCaGP/C. C. albicans was susceptible to nanocompounds produced with both reducing agents, regardless of Ag concentration and CaGP form, being Ag10%CaGP-N/C the most effective compound (19.5&ndash, 39.0 &micro, g Ag mL&minus, 1). While for S. mutans, the effectiveness was observed only for AgCaGP reduced by citrate, also presenting Ag10%CaGP-N the highest effectiveness (156.2&ndash, 312.5 &micro, 1). Notably, CaGP enhanced the silver antimicrobial potential in about two- and eight-fold against C. albicans and S. mutans when compared with the AgNP controls (from 7.8 to 3.9 and from 250 to 31.2 &micro, 1, respectively). The synthesis that was used in this study promoted the formation of AgNP associated with CaGP, and although the use of sodium borohydride (B) resulted in a pronounced reduction of Ag+, the composite AgCaGP/B was less effective against the microorganisms that were tested.

Made available in DSpace on 2018-12-11T16:54:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-07-01 The phytosynthesis of metal nanoparticles is nowadays attracting the increased attention of researchers and is much needed given the worldwide matter related to environmental contamination. The antimicrobial activity of colloidal and spray formulation of silver nanoparticles (AgNPs) synthesized by pomegranate peel extract against Candida albicans and Staphylococcus aureus, and their cytotoxicity in mammalian cells were tested in the present study. Dry matter, pH, total phenolics, and ellagic acid in the extract were determined. Then, AgNPs were phytosynthesized and characterized by X-ray diffraction, electron transmission microscopy, dynamic light scattering, zeta potential, and Ag+ dosage. Spray formulations and respective chemical-AgNP controls were prepared and tested. The peel extract reduced more than 99% of Ag+, and produced nanoparticles with irregular forms and an 89-nm mean size. All AgNP presented antimicrobial activity, and the spray formulation of green-AgNP increased by 255 and 4 times the effectiveness against S. aureus and C. albicans, respectively. The cytotoxicity of colloidal and spray green-AgNP was expressively lower than the respective chemical controls. Pomegranate peel extract produced stable AgNP with antimicrobial action and low cytotoxicity, stimulating its use in the biomedical field. Department of Dentistry University Center of Adamantina (UNIFAI) Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry Laboratory of Research Development & Innovation Apis Flora Industrial e Comercial Ltda Department of Chemistry Federal University of São Carlos FACET-Department of Chemistry Federal University of Grande Dourados Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) School of Dentistry

Made available in DSpace on 2018-12-11T17:18:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-16 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) This study aimed to synthesize and characterize materials containing silver nanoparticles (AgNP) with polyphosphates (sodium trimetaphosphate (TMP) or sodium hexametaphosphate (HMP), and evaluate their effect against Candida albicans and Streptococcus mutans. The minimum inhibitory concentration (MIC) was determined, which was followed by the quantification of the biofilm by counting colony-forming units (CFUs), the amount of metabolic activity, and the total biomass. The MICs revealed greater effectiveness of composites containing 10% Ag (TMP + Ag10% (T10) and HMP + Ag10% (H10)) against both microorganisms. It was observed that T10 and H10 reduced the formation of biofilms by 56–76% for C. albicans and by 52–94% for S. mutans for total biomass and metabolic activity. These composites promoted significant log reductions in the number of CFUs, between 0.45–1.43 log10 for C. albicans and 2.88–3.71 log10 for S. mutans (p

Aim: To synthesize, characterize and evaluate the antimicrobial and antibiofilm activities of novel nanocomposites containing silver nanoparticles (AgNPs) associated or not to β-calcium glycerophosphate. Materials & methods: These nanocomposites were produced through a ‘green’ route using extracts of different parts of pomegranate. Antimicrobial and antibiofilm properties against Candida albicans and Streptococcus mutans were determined by the minimum bactericidal/fungicidal concentration and biofilm density after treatments. Results: All extracts used were successful in producing AgNPs. Composites made with peel extracts showed the highest antimicrobial and antibiofilm activity against both microorganisms tested and performed similarly or even better than chlorhexidine. Conclusion: AgNPs associated or not to calcium glycerophosphate produced by a ‘green’ process may be a promising novel antimicrobial agent against oral microorganisms.

Microtubules were constructed by covering the fungus Aspergillus aculeatus sequentially with silver and gold nanoparticles, resulting in a stable hybrid mesostructured material that presented three distinct regions containing different combinations of silver and gold nanoparticles. These heterogeneities were determined by the hyphal growth since the impossibility to cover the dead fungus, which suggests the influence of the secondary metabolites produced by living fungus in the deposition mechanism.

A systematic study of the electrochemical reduction of graphene oxide was performed. The graphene oxide was reduced electrochemically in phosphate buffer solution by applying potential of −0.8 V for different times. The graphene oxide and the electrochemically reduced graphene oxide were characterized using ex - situ field-emission gun scanning electron microscopy, in - situ Raman scattering and in - situ atomic force microscopy. Raman scattering showed that the reduction process is accompanied by an increase in the ratio between the D and the G bands of graphene, while the microscopies analyses revealed that the reduction procedure promotes changes in the morphology of the graphene oxide sheets that lead to an increase of the system roughness. Electrochemical impedance spectroscopy showed that reduction of graphene oxide promotes a decrease of the charge-transfer resistance upon electrochemical reduction. This observation was in agreement with the changes observed using cyclic voltammetry, which showed a reduction process improve the reversibility and increase the current peak. The increase in the roughness and an improvement of the electronic mobility brought upon electrochemical reduction are a function of the increase in the edge plane-like defects in the graphene layers.

The ability to control the assembly of nanoparticles on substrates used in plasmon-enhanced spectroscopy continues to drive research in the field of nanofabrication. Here we describe the use of fungi as soft biotemplates to fabricate nanostructured microtubules with gold and gold-silver nanoparticles with potential applications as sensors and biosensors. In the first step, spores of the filamentous fungus Cladosporium sphaerospermum were inoculated in a suspension of gold nanoparticles, forming stable microtubules of gold nanoparticles during fungus growth. These materials were exposed to a second suspension of silver nanoparticles, resulting in complexes multilayers structures of gold and silver nanoparticles, which were evaluated as substrates for surface-enhanced Raman scattering (SERS) using small amounts of thiophenol as probe molecules directly on the microtubules. Both gold and the gold-silver substrates provide the SERS effect.

Made available in DSpace on 2018-12-11T17:10:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-06-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objective: This study evaluated the effect of toothpastes containing 1100 ppm F associated with nano-sized sodium hexametaphosphate (HMPnano) on enamel demineralization in vitro using a pH-cycling model. Design: Bovine enamel blocks (4 mm × 4 mm, n = 72) selected by initial surface hardness (SHi) were randomly allocated into six groups (n = 12), according to the test toothpastes: without fluoride or HMPnano (Placebo), 550 ppm F (550F), 1100 ppm F (1100F), 1100F plus HMPnano at concentrations of 0.25% (1100F/0.25%HMPnano), 0.5% (1100F/0.5%HMPnano), and 1.0% (1100F/1.0%HMPnano). Blocks were treated 2×/day with slurries of toothpastes and submitted to five pH cycles (demineralizing/remineralizing solutions) at 37 °C. Next, final surface hardness (SHf), integrated loss subsurface hardness (ΔKHN), integrated mineral loss (gHAp × cm−3), and enamel fluoride (F) concentrations were determined. Data were analyzed by ANOVA and Student-Newman-Keuls test (p 0.001). Conclusion: The addition of 0.5%HMPnano to a 1100 F toothpaste significantly enhances its effects against enamel demineralization when compared to its counterpart without HMPnano in vitro. Clinical significance: Toothpaste containing 1100 ppm F associated with HMPnano has a higher potential to reduce the demineralization compared to 1100 ppm F. This toothpaste could be a viable alternative to patients at high risk of caries. Department of Pediatric Dentistry and Public Health São Paulo State University (Unesp) School of Dentistry Araçatuba, Rua José Bonifácio 1193 LIEC-Department of Chemistry Federal University of São Carlos (UFSCar), Rodovia Washington Luís Department of Pediatric Dentistry and Public Health São Paulo State University (Unesp) School of Dentistry Araçatuba, Rua José Bonifácio 1193 FAPESP: 2014/06676-9

Department of Pediatric Dentistry and Public Health Sao Paulo State University (Unesp) School of Dentistry, Rua Jose Bonifacio 1193

The application of nanosized and nanostructured materials in ordinary life is the other side of the coin that emerged from the scientific progress. It established a new interdisciplinary point of view about the behavior of atoms and molecules at a very small scale, leading to an unprecedented understanding over several aspects of the matter and a whole knowledge on its fundamental properties never imagined before. These nanomaterials provide innovative solutions in technological and environmental fields related to solar energy conversion, catalysis, medicine, and water treatment. Usually, these novel and enhanced characteristics that are easily found in metallic nanoparticles are related to their high surface-to-volume ratio. In this sense, silver nanoparticles have been the subject of substantial research especially for medical and health applications. For decades, people have been using colloidal silver for their own health benefits, but detailed studies on its effects in the environment have only recently begun. Initial studies demonstrated that cells and microbes are primarily affected by low levels of silver ion (Ag+) released from the nanoparticle. Due to the increasing use of silver nanoparticles in products for daily use, such as in shampoos, soaps, detergents, cosmetics, toothpastes, and medical and pharmaceutical products, there has been a major effort worldwide to assess the safety of using silver nanoparticles and to understand how these nanoparticles effectively kill several microorganisms. Silver has been considered as a potential disinfectant in many investigations due to its intense antimicrobial activity and low toxicity to mammalian cells and tissues. It is one of the most powerful natural disinfectants known, reason by which its deposition onto prosthetic device surfaces (e.g., catheters, heart valves, etc.) would be an attractive approach for preventing bacterial attachment and biofilm formation, which can lead to serious infections. Another potential application could be in food processing equipment and packaging materials, where the presence of undesirable bacteria can cause food spoilage and foodborne diseases. For this reason, an increasingly common application is the use of silver nanoparticles for antimicrobial coatings, many textiles, polymer, and biomedical devices that contain silver nanoparticles to provide protection against bacteria and fungi. Silver nanoparticles coated in the polymer matrix increase the efficiency of antimicrobial action with a controlled release of Ag+. The combination of silver with polymeric material reduces the transmission of the infectious agent. This chapter will describe nanostructured functional polymer materials containing silver nanoparticles for the generation of antimicrobial characteristics.

Although silver nanoparticles (SN) have been investigated as an alternative to conventional antifungal drugs in the control of Candida-associated denture stomatitis, the antifungal activity of SN in combination with antifungal drugs against Candida biofilms remains unknown. Therefore, the aim of this study was to evaluate the antifungal efficacy of SN in combination with nystatin (NYT) or chlorhexidine digluconate (CHG) against Candida albicans and Candida glabrata biofilms. The drugs alone or combined with SN were applied on mature Candida biofilms (48 h), and after 24 h of treatment their antibiofilm activities were assessed by total biomass quantification (by crystal violet staining) and colony forming units enumeration. The structure of Candida biofilms was analysed by scanning electron microscopy (SEM) images. The data indicated that SN combined with either NYT or CHG demonstrated synergistic antibiofilm activity, and this activity was dependent on the species and on the drug concentrations used. SEM images showed that some drug combinations were able to disrupt Candida biofilms. The results of this study suggest that the combination of SN with NYT or CHG may have clinical implications in the treatment of denture stomatitis. However, further studies are needed before recommending the use of these drugs safely in clinical situations., The authors thank CAPES (grant BEX 1221/10-8) and FAPESP (2009/15146-5), Brazil, for supporting Douglas Roberto Monteiro work. They also thank David Williams (Cardiff University, Cardiff, UK) for providing the strain 324LA/94, and Valentim Adelino Ricardo Barao for the English review. Silver colloidal nanoparticles used herein were prepared and characterised by LIEC-CMDMC and INCTMN/FAPESP-CNPq, Sao Carlos, Brazil.

Biofilms may compromise wound healing, because of their tolerance to antimicrobials. Control of biofilms has been achieved with combinations of drugs and alternative antimicrobial agents. Silver nanoparticles have been the subject of substantial research for medical and health applications, and there is a remarkable international effort underway to verify their safety and to understand how these nanoparticles effectively kill several microorganisms. The use of silver nanoparticles in natural products with medicinal importance is a relatively new concept and is a widely accepted technology with rapid production capabilities and minimum impact on human health and environmental quality. This chapter presents the importance of studying biofilms, especially in chronic wounds using in vitro models, and emphasizes the potential green synthesis of silver nanoparticles.

Aim: The purpose of this work was to evaluate the size-dependent antifungal activity of different silver nanoparticles (SN) colloidal suspensions against Candida albicans and Candida glabrata mature biofilms. Methods and Results: The research presented herein used SN of three different average sizes (5, 10 and 60 nm), which were synthesized by the reduction of silver nitrate through sodium citrate and which were stabilized with ammonia or polyvinylpyrrolidone. Minimal inhibitory concentration (MIC) assays were performed using the microdilution methodology. The antibiofilm activity of SN was determined by total biomass quantification (by crystal violet staining) and colony forming units enumeration. MIC results showed that all SN colloidal suspensions were fungicidal against the tested strains at very low concentrations (0AE4‐3AE3 l gm l )1 ). With regard to biomass quantification, SN colloidal suspensions were very effective only against C. glabrata biofilms, achieving biomass reductions around 90% at a silver concentration of 108 l gm l )1 .I n general, all SN suspensions promoted significant log10 reduction of the mean number of cultivable biofilm cells after exposure to silver concentrations at or higher than 108 l gm l )1 . Moreover, the results showed that the particle size and the type of stabilizing agent used did not interfere in the antifungal activity of SN against Candida biofilms. Conclusions: This study suggests that SN have antifungal therapeutic potential, but further studies are still required namely regarding formulation and delivery means. Significance and Impact of the Study: SN may contribute to the development of new strategies for the improvement of oral health and quality of life particularly of the complete denture wearers.

Purpose: The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. Materials and Methods: A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers’ instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Results: Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Conclusions: Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers.

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n ¼ 2) and C. glabrata (n ¼ 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4–3.3 m gm l 71 ). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction *90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

Purpose: Silver nanoparticles (SN) have been studied as antibiofilm agents, to prevent Candida-associated denture stomatitis. Consequently, the aim of this study was to investigate the influence of the intermediate and maturation stages of Candida albicans and Candida glabrata biofilms development in the susceptibility to SN. Methods: SN (5 nm) suspensions were synthesized via reduction of silver nitrate by a solution of sodium citrate. These suspensions were used to treat, during 5 h, Candida biofilms grown on acrylic surfaces for 24- (intermediate stage) and 48-h (maturation stage), and their efficacy was determined by total biomass (using crystal violet staining) and colony forming units (CFU) quantification. Results: SN promoted significant reductions (p < 0.05) in the total biomass and in the number of CFUs of Candida biofilms ranging from 23-51.5% and 0.96-1.44-log10, respectively. Moreover, there were no significant differences in the total biofilm biomass (p > 0.05), when the different stages of biofilm development (24 or 48 h) were exposed to SN. Comparing the number of CFUs between 24- and 48-h biofilms treated with SN, a significant difference (p < 0.05) was found only for the strain C. albicans 324LA/94. Conclusions: It was concluded that, in general, the intermediate and maturation stages of biofilm development do not interfere in the susceptibility of C. albicans and C. glabrata biofilms to SN regarding. These findings are essential for the deployment of new therapies aimed at preventing denture stomatitis., This study was supported by the Sao Paulo Research Foundation (FAPESP), Brazil, process 2009/15146-5. The authors are indebted to LIEC-CMDMC and INCTMN/FAPESP-CNPq in the name of Andressa Kubo for preparing and characterizing the colloidal suspensions of silver nanoparticles. We also thank Dr. David Williams (Cardiff University, Cardiff, UK) for providing the strain 324LA/94, and George Duchow for the English review.

[Exert] This chapter is focused on the activity of silver nanoparticles (SN) as an antifungal agent against Candida albicans and Candida glabrata biofilms, which are involved in oral candidosis. A discussion focusing on the influence of the stabilizing agent, diameter of SN on its antibiofilm activity, influence of chemical stability of SN on Candida biofilms, the effect of SN against adhered cells and biofilms, the effect on extracellular matrix composition and structure of Candida biofilms, the combination of SN with conventional antifungal drugs, and the incorporation of SN into denture acrylic resin is incorporated in the present chapter. Because of the resistance of Candida biofilms to conventional drugs and the positive effect of SN against them, these nanoparticles can be used as an alternative antifungal agent (...)., (undefined)

Our aim in this study was to evaluate how the chemical stability of silver nanoparticles (SNs) influences their efficacy against Candida albicans and C. glabrata biofilms. Several parameters of SN stability were tested, namely, temperature (50ºC, 70ºC, and 100ºC), pH (5.0 and 9.0), and time of contact (5 h and 24 h) with biofilms. The control was defined as SNs without temperature treatment, pH 7, and 24 h of contact. These colloidal suspensions at 54 mg/L were used to treat mature Candida biofilms (48 h) formed on acrylic. Their efficacy was determined by total biomass and colony-forming unit quantification. Data were analyzed using analysis of variance and the Bonferroni post hoc test (=0.05). The temperature and pH variations of SNs did not affect their efficacy against the viable cells of Candida biofilms (P > 0.05). Moreover, the treatment periods were not decisive in terms of the susceptibility of Candida biofilms to SNs. These findings provide an important advantage of SNs that may be useful in the treatment of Candida-associated denture stomatitis., We thank Dr David Williams, Cardiff University, Cardiff, UK, for providing the strain 324LA/94. The authors also thank Sao Paulo Research Foundation (FAPESP, process 2009/15146-5), Brazil, for supporting the work of D. R. M. The authors are indebted to Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Federal University of Sao Carlos, Brazil, in the name of Andressa Kubo, for preparing and characterizing the colloidal suspensions of silver nanoparticles.

This study investigated the adhesion to human epithelial cells and polystyrene surface of viable yeasts recovered from Candida biofilms treated with silver nanoparticles (SN). Biofilm resuspended Candida cells were added to HeLa cells or to empty wells of microtiter plates and the adhesion was verified using crystal violet staining. The adhesion of Candida cells was significantly reduced, mainly when biofilms were pretreated with 54 μg/mL SN. These new findings allow to conclude that SN may induce changes in viable yeasts, which can decrease the dissemination of Candida infections, mainly in susceptible patients., We thank Dr. David Williams (Cardiff University, Cardiff, UK) for providing the strain 324LA/94, and George Duchow for the English review. Silver colloidal nanoparticles used herein were prepared by LIEC-CMDMC and INCTMN/FAPESP-CNPq, Sao Carlos, Brazil. This study was supported by CAPES (grant BEX 1221/10-8) and FAPESP (2009/15146-5), Brazil.

Aim : The aim of this study was to assess the effect of different silver nanoparticles (SN) concentrations on the matrix composition and structure of Candida albicans and Candida glabrata biofilms. Methods and Results : Candida biofilms were developed in 6-well microtiter plates during 48 h. After, these biofilms were exposed to 13·5 or 54 μg SN ml−1 for 24 h. Then, extracellular matrices were extracted from biofilms and analysed chemically in terms of proteins, carbohydrates and DNA. To investigate the biofilm structure, scanning electron microscopy (SEM) and epifluorescence microscopy were used. SN interfered with the matrix composition of Candida biofilms tested in terms of protein, carbohydrate and DNA, except for the protein content of C. albicans biofilm. By SEM, Candida biofilms treated with SN revealed structural differences, when compared with the control groups. Further, SN showed a trend of agglomeration within the biofilms. Epifluorescence microscopy images suggest that SN induced damage on cell walls of the Candida isolates tested. Conclusions : In general, irrespective of concentration, SN affected the matrix composition and structure of Candida biofilms and these findings may be related to the mechanisms of biocide action of SN. Significance and Impact of the Study : This study reveals new insights about the behaviour of SN when in contact with Candida biofilms. SN may contribute to the development of therapies to prevent or control Candida infections., We thank David Williams (Cardiff University, Cardiff, UK) for providing strain 324LA/94. The authors also thank CAPES (grant BEX 1221/10-8) and FAPESP (2009/15146-5), Brazil, for supporting Douglas Roberto Monteiro work. The colloidal suspension of silver nanoparticles used herein was prepared and characterized by LIEC-CMDMC and INCTMN/FAPESP-CNPq, Sao Carlos, Brazil.

The purpose of this study was to examine the effect of silver nanoparticles (SN) and nystatin on pre-formed biofilms (single and dual species combinations of Candida glabrata and Candida albicans). Thus, adhesion and biofilm assays were performed on acrylic surface in presence of artificial saliva (AS), during 2 h and 48 h, respectively. Candida glabrata and C. albicans adhered cells were determined by counting recovered colony forming units (CFUs) on CHROMagar® Candida. In addition, crystal violet (CV) staining, as an indicator of biomass, was used to quantify biofilm formation ability. Furthermore, pre-formed biofilms were treated either with SN or nystatin and its effects on biofilms evaluated after 24 h. The results showed that both Candidia species adhered to, and formed biofilms on acrylic. Candida glabrata biofilms had significantly higher CFUs compared with biofilms of C. albicans (P, The authors acknowledge FCT, Portugal, for supporting Sonia Silva's work through grant SFRH/BPD/71076/2010 and CAPES, Brazil, for supporting Douglas Roberto Monteiro's work through grant BEX 1221/10-8 and Melyssa Negri through BEX-4642/06-6. We also thank UFSCar, LIEC-CMDMC and INCTMN/FAPESP-CNPq for preparing and characterizing the silver colloidal nanoparticle suspensions.