Abstract: Objeticve. The aim of this study was to develop a composite material with antibacterial activ-ity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMAmatrix and added low concentration of MMT/CHX. The aim was to evaluate the drug releasecapacity of MMT, and not to provide reinforcement.Methods. Six experimental composites were made with organic matrix of BisGMA/TEGDMAin equal proportions by weight. The composites received organophlizated montmorillonitewith or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion(DC) was evaluated using FTIR (peak 6165 cm-1; n = 5). Specimens for flexural properties(10×2×1 mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS)was measured using the three point bending test (n = 10). Inibition halo was used to test theantibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonasgingivalis (n = 5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated byinserting polymerized disc of composite in to a culture media colonized with Streptococcusmutans (n = 10). The release of CHX was measured using ultraviolet (255 nm) for 10 days(n = 5). The data of degree of conversion was analysed using Kruskal–Wallis/ Mann–Whitney,and the other variables using two-way ANOVA/Tukey, always considering a global level ofsignificance of 5%.Results. DC ranged from 71% to 74%. E ranged from 5.7 to 8.1 GPa. FS ranged from 61.4 to74.7 MPa. There were no statistical differences among the groups for all the variables. Forthe three bacteria tested the composites with CHX loaded presented inhibition of growthfor all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BFwas lower for the groups with 10% MMT/CHX, all groups presented BF, even those withoutCHX loaded. All concentrations presented release off CHX during all the 28 days analyzed. Conclusions. Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated.

Palavras-Chave: composite materials; germicides; dentistry; manganese compounds; chlorine compounds; bacteria; staphylococcus; streptococcus; antimicrobial agents; resins

BOARO, LETICIA C.C.; CAMPOS, LUIZA M.; VARCA, GUSTAVO H.C.; SANTOS, TAMIRIS M.R. dos; MARQUES, PAMELA A.; SUGII, MARI M.; SALDANHA, NATHALIA R.; COGO-MULLER, KARINA; BRANDT, WILLIAM C.; BRAGA, ROBERTO R.; PARRA, DUCLERC F. Antibacterial resin-based composite containing chlorhexidine for dental applications. Dental Materials, v. 35, n. 6, p. 909-918, 2019. DOI: 10.1016/j.dental.2019.03.004. Disponível em: http://repositorio.ipen.br/handle/123456789/29927. Acesso em: $DATA.

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Abstract: High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Polypropylene (PP), and recycled Poly(Ethylene Terephthalate) (PET) are widely applied as packaging materials worldwide, and they correspond to more than 50 % of the plastic residues present in municipal solid waste. Currently, it is needed to develop effective methods to ensure the identification and sorting of plastic waste to guarantee necessary purity to obtain quality and economically viable recycled goods from post-consumer plastic. As an attempt to that, we investigated the applicability of Confocal Raman Scattering Spectroscopy (Confocal Raman) combined with Principal Component Analysis (PCA), Linear Partial Least Squares Regression by Intervals (iPLS-R) and Competitive Adaptive Weighted Sampling (CARS/PLS-R) as fast chemometric tools to identify and classify pristine and recycled mixtures of HDPE and LDPE from municipal solid waste in São Paulo, Brazil. We found several limitations in applying this procedure to classify the different polyethylenes and their polymer blends using the Principal Components (PC) from PCA analysis. iPLS-R regression model presents more effectiveness than the CARS/PLS-R model to detect the LDPE content in recycled HDPE/LDPE blends, both being influenced by different contaminants (PP, PET, SiO2, and CaCO3) added in these recycled plastics.

Palavras-Chave: raman spectroscopy; polyethylenes; wastes; plastics; thermal gravimetric analysis

SILVA, DANIEL J. da; PARRA, DUCLERC F.; WIEBECK, HELIO. Applying confocal Raman spectroscopy and different linear multivariate analyses to sort polyethylene residues. Chemical Engineering Journal, v. 426, p. 1-13, 2021. DOI: 10.1016/j.cej.2021.131344. Disponível em: http://repositorio.ipen.br/handle/123456789/32457. Acesso em: $DATA.

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Abstract: Bioinspired bactericidal surfaces are artificial surfaces that mimic the nanotopography of insect wings and are capable of inhibiting microbial growth by a physicomechanical mechanism. The scientific community has considered them an alternative method to design polymers with surfaces that inhibit bacterial biofilm formation, suitable for self-disinfectant medical devices. In this contribution, poly(lactic acid) (PLA) with nanocone patterns was successfully produced by a novel two-step procedure involving copper plasma deposition followed by argon plasma etching. According to reverse transcription-quantitative polymerase chain reaction tests, the bioinspired PLA nanostructures display antiviral performance to inactivate infectious Omicron severe acute respiratory syndrome coronavirus 2 particles, reducing the amount of the viral genome to less than 4% in just 15 min due to a possible combined effect of mechanical and oxidative stress. The bioinspired antiviral PLA can be suitable for designing personal protection equipment to prevent the transmission of contagious viral diseases, such as Coronavirus Disease 2019.

Palavras-Chave: coronaviruses; topography; surfaces; copper; lactic acid; polymers; antimicrobial agents

SILVA, DANIEL J. da; DURAN, ADRIANA; CABRAL, ALINE D.; FONSECA, FERNANDO L.A.; WANG, SHU H.; PARRA, DUCLERC F.; BUENO, RODRIGO F.; PEREYRA, INES; ROSA, DERVAL S. Bioinspired antimicrobial PLA with nanocones on the surface for rapid deactivation of Omicron SARS-CoV‑2. ACS Biomaterials Science and Engineering, v. 9, n. 4, p. 1891-1899, 2023. DOI: 10.1021/acsbiomaterials.2c01529. Disponível em: http://repositorio.ipen.br/handle/123456789/34016. Acesso em: $DATA.

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Abstract: Materials with antimicrobial properties are highly desirable for making food packaging and personal protective equipment due to their intrinsic ability to prevent the proliferation of pathogenic microorganisms and food contamination. Poly(lactic acid) (PLA) is a biodegradable, compostable, and recyclable polymer that presents interesting mechanical properties for such applications. However, this polymer does not show intrinsic antimicrobial activity. Herein, we applied Radio Frequency Magnetron Sputtering (RF-MS) to produce antimicrobial copper coatings on the PLA surface. The results indicate that the prolongation in the copper deposition time causes an increase in surface roughness. The PLA coating with copper using a short deposition time (5–20 s) was sufficient to guarantee a bactericidal effect against Escherichia coli and Bacillus subtilis, in addition to conferring antiviral activity against Omicron Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Nuclear magnetic resonance (NMR) and high-resolution x-ray photoelectron (XPS) spectroscopic studies indicate that occurs only localized degradation on the PLA surface via polymer chain scission. The RF-MS technique was suitable for rapidly manufacturing antimicrobial Cu-coated PLA and providing low copper consumption in the antimicrobial coating process.

Palavras-Chave: coronaviruses; polymers; lactic acid; copper; plasma; coatings; antimicrobial agents

SILVA, DANIEL J. da; FERREIRA, GREICIELE S.; DURAN, ADRIANA; FONSECA, FERNANDO L.A.; PARRA, DUCLERC F.; BUENO, RODRIGO F.; ROSA, DERVAL S. Copper coatings on poly(lactic acid) via rapid magnetron sputtering: morphology, chemistry, and antimicrobial performance against bacteria and SARS-CoV-2. Materials Today Communications, v. 34, p. 1-13, 2023. DOI: 10.1016/j.mtcomm.2023.105440. Disponível em: http://repositorio.ipen.br/handle/123456789/33993. Acesso em: $DATA.

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Abstract: This paper evaluates corn starch aerogels, studying different crosslinking agent (trisodium citrate) concentrations (1:1, 1:1.5, and 1:2) and sorption conditions (contact time, adsorbent weight, and initial concentration) regarding the potentially toxic elements (PTEs) [Cd(II) or Zn(II)] adsorption of the aqueous systems. Besides, other properties of aerogels, such as structural properties, specific surface area, and mechanical performance, were evaluated. For adsorption results, better values were observed in adsorption capacity and efficiency for the initial concentration of 100 ppm. In addition, an adsorption time of 12 h and an adsorbent weight of 3.0 g obtained better results due to the possible balance in this time and the high specific surface area available for Cd(II) adsorption. As for the type of adsorbent, the Aero 1:1.5 sample (intermediate crosslinking agent concentration) obtained better results, possibly due to the high porosity, smaller pore sizes, high pore density, and high specific surface area (198 m2·g−1). In addition, hydroxyl groups in the starch aerogel removed Cd(II) ions with 30 % adsorption efficiency. Lastly, Aero 1:1.5 obtained a high mechanical strength at compression and a satisfactory compressive modulus. In contrast, starch aerogels did not absorb the Zn(II) ion.

Palavras-Chave: maize; starch; gels; adsorption; elements; toxic materials

CAMANI, PAULO H.; MIDHUN DOMINIC, C.D.; PARRA, DUCLERC F.; MALTEZ, HELOISA F.; ROSA, DERVAL S. Divalent metal ion removal from simulated water using sustainable starch aerogels: effect of crosslinking agent concentration and sorption conditions. International Journal of Biological Macromolecules, v. 226, p. 628-645, 2023. DOI: 10.1016/j.ijbiomac.2022.11.308. Disponível em: http://repositorio.ipen.br/handle/123456789/33982. Acesso em: $DATA.

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Abstract: This study had as its main objective to evaluate the flexural properties (strength and modulus) and degree of conversion of a dimethacrylate resin containing different amounts of nanoparticulated clay Montomorillonite (MMT) as filler. A series of composites containing similar amounts (in volume) of barium glass particles was also tested as control data. Eight formulations with polymeric matrix-based BisGMA/TEGDMA (Bisphenol A Bis(2-hydroxy-3 methacryloxypropyl)Ether/ Triethyleneglycol Dimethacrylate), four added with MMTand four added with barium glass in the volume concentration of 20, 30, 40 and 50 vol% were studied. The degree of conversion was determined using near-IR spectroscopy. Elastic modulus and flexural strength were determined by the three-point bending test. The dispersion of MMT nanoparticles was determined by means of X-ray diffraction and transmission electron microscopy analysis. The fillers montomorillonite and barium glass interacted with polymer matrix-based BisGMA/TEGDMA in a distinct manner. Although the addition of montomorillonite nanoparticles resulted in similar degree of conversion and higher elastic modulus values at all concentrations tested, only at the 20 vol% the flexural strength was statistically higher, compared to the control groups filled with barium glass. This could be related to the need of concentration optimization of montomorillonite for each type of polymer matrix in order to adjust or improve mechanical properties. The addition of low concentrations (<l 20% vol) of montomorillonite nanoparticles in dental composites resins – such as additive or hybrid filler – should be studied, aiming to the reduction of polymerization shrinkage, better mechanical properties and improvement of a new technology for future applications.

Palavras-Chave: evaluation; montmorillonite; nanoparticles; clays; nanocomposites; mechanical properties; flexural strength; x-ray diffraction; transmission electron microscopy; scanning electron microscopy

CAMPOS, LUIZA M.P.; BOARO, LETICIA C.; SANTOS, TAMIRIS M.R.; MARQUES, PAMELA A.; ALMEIDA, SONIA R.Y.; BRAGA, ROBERTO R.; PARRA, DUCLERC F. Evaluation of flexural modulus, flexural strength and degree of conversion in BISGMA/TEGDMA resin filled with montmorillonite nanoparticles. Journal of Composite Materials, v. 29, p. 1-11, 2016. DOI: 10.1177/0021998316656925. Disponível em: http://repositorio.ipen.br/handle/123456789/26970. Acesso em: $DATA.

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