Abstract: At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.

Palavras-Chave: gold; nanoparticles; gamma radiation; electron beams; x-ray sources; radiolysis; nanotechnology; medicine; diagnostic uses; ionizing radiations

FREITAS, LUCAS F. de; VARCA, GUSTAVO H.C.; BATISTA, JORGE G. dos S.; LUGAO, ADEMAR B. An overview of the synthesis of gold nanoparticles using radiation technologies. Nanomaterials, v. 8, n. 11, 2018. DOI: 10.3390/nano8110939. Disponível em: http://repositorio.ipen.br/handle/123456789/29423. Acesso em: $DATA.

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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: Radiolytic synthesis and phytochemical-driven gold reduction for the generation of nanoparticles are successful examples of Green Chemistry applied for nanomaterials. The present work compares these two green approaches focusing on hydrodynamic size, stability over time, optical properties and toxicity in NIH 3T3 (ATCC® CRL- 1658™) cells and Danio rerio (Zebra Fish). The radiolytic synthesis was performed by mixing 1 mM NaAuCl4; polyvinyl pyrrolidone 0.5%, AgNO3 6×10−5 M, propan-2-ol 0.2 M and acetone 0.06 M, followed by irradiation at 15 kGy (5 kGy h−1, 60Co source). The EGCG-functionalized nanoparticles were synthesized by mixing 1.6 mM of Au with 0.8 mM of EGCG in phosphate buffer (10 mM) for 2 h. Both methods yield the formation of gold nanoparticles featuring plasmon resonance bands at 520–530 nm, polydispersity above 0.3 was relevant only for the radiolytic protocol. Regarding stability over time, after 30 days, the nanoparticles synthesized radiolytically presented no relevant size changes, while some aggregation was observed for the EGCG-particles. The same nanoparticles demonstrated a lack of stability in high ionic strength medium. Slight toxicity was observed for the EGCG-nanoparticles in Danio rerio, with an IC50 calculated as 40.49%, while no IC50 was established within the concentration range of radiolysis-AuNPs used in this study. In conclusion, both green methods generated nanoparticles with good control of size and optical properties, especially via reduction by EGCG. However, the stability and toxicity results were found to be more promising for the radiolytically synthesized gold nanoparticles.

Palavras-Chave: gold; nanoparticles; synthesis; chemistry; ecology; polyphenols; fishes

FREITAS, LUCAS F. de; CRUZ, CASSIA P.C. da; CAVALCANTE, ADRIANA K.; BATISTA, JORGE G. dos S.; VARCA, GUSTAVO H.C.; MATHOR, MONICA B.; LUGAO, ADEMAR B. Comparison between gold nanoparticles synthesized by radiolysis and by EGCG-driven gold reduction. Radiation Physics and Chemistry, v. 174, p. 1-9, 2020. DOI: 10.1016/j.radphyschem.2020.108959. Disponível em: http://repositorio.ipen.br/handle/123456789/31427. Acesso em: $DATA.

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Abstract: Technological advances have promoted improvements in several science fields, especially related to environmental and analytical areas with the improvement of detection and development of environmentally friendly extraction techniques. This study applied Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) for soil extraction and assessed its performance through a validation study using samples from the soil of a contaminated area in Caieiras, SP, Brazil. Nine organochlorine pesticides, including the isomers alpha, beta, gamma and delta- hexachlorocyclohexane; cis- and trans-heptachlor epoxide; cis- and trans-chlordane and heptachlor were analyzed by gas chromatography coupled to electron capture detector. The method was validated according to ISO 5725-4 (2020), EURACHEM (2014) and DOQ-CGCRE-008 (2016). The limits of detection and quantification of the method for the nine organochlorines were α-HCH (1.2 and 12.6 µg kg−1), β-HCH (1.7 and 12.0 µg kg−1), γ-HCH (1.5 and 11.6 µg kg−1), δ-HCH (0.8 and 11.6 µg kg−1), heptachlor (1.0 and 10.8 µg kg−1), cis-heptachlor epoxide (0.9 and 11.5 µg kg−1), trans-heptachlor epoxide (0.9 and 11.5 µg kg−1), cis-chlordane (0.4 and 7.9 µg kg−1) and trans-chlordane (0.5 and 10.9 µg kg−1), respectively, and all of them were within the maximum limits recommended by the EPA for the compounds α-HCH (86.0 and 360.0 µg kg−1), β-HCH (300.0 and 1.3 × 103 µg kg−1), γ-HCH (570.0 and 2.5 × 103 µg kg−1), δ-HCH (not defined), heptachlor (130.0 and 630.0 µg kg−1), cis-/trans-heptachlor epoxide (7.0 and 330.0 µg kg−1), cis-/trans-chlordane (1.77 × 103 and 7.7 × 103 µg kg−1) in residential and industrial soil, respectively. Recovery results were between 65% and 105% for almost all compounds, which is an optimum result for multi-residue analytical methods, considering the complexity of the matrix used in the study. Caieiras presented contamination levels of α-HCH in the range of 2.0 to 66.0 µg g−1, which was higher than the limits established by EPA, corresponding to 0.077 µg g−1 for residential soil and 0.27 µg g−1 for industrial soil. According to the validation study, the analytical method proposed was reliable for organochlorine quantification, and the QuEChERS was considered efficient for organochlorine extraction from soil.

Palavras-Chave: organic chlorine compounds; soils; urban areas; pollution; sanitary landfills; land pollution; pesticides; environmental impacts; validation; electron-capture detectors

VARCA, JUSTINE P.R.O.; MARTINS, ELAINE A.J.; VARCA, GUSTAVO H.C.; ROMANO, RENATO L.; LEBRE, DANIEL T.; LAINETTI, PAULO E.O.; BUSTILLOS, JOSE O.V. Determination of organochlorines in soil of a suburban area of São Paulo Brazil. International Journal of Environmental Research and Public Health, v. 17, n. 16, p. 1-16, 2020. DOI: 10.3390/ijerph17165666. Disponível em: http://repositorio.ipen.br/handle/123456789/31473. Acesso em: $DATA.

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Abstract: In this paper, ecological-friendly materials based on ethylene–propylene–diene terpolymer (EPDM) with improved thermal and radiation stabilities by Chlorella vulgaris (CV) and Spirulina platensis (SP) powders were investigated by complementary procedures: FTIR spectroscopy and isothermal and nonisothermal chemiluminescence (CL). The stabilization potential of microalgae was evaluated at several degrees of γ-radiolysis by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, while the polymer resistances were studied on a large range of algal concentrations (1, 3, 5 and 10 mass%). The carbonyl and hydroxyl indices of all degraded EPDM formulations were found to be two times smaller in the presence of algal powders, if compared to the pristine material. Some dissimilarities between the oxidation development in pristine and modified EPDM appeared, especially in unirradiated samples. The activation energies required for the oxidation of EPDM and the lifetime of these samples at various temperatures between room temperature and 100 °C were calculated. The antioxidant compounds existing in the studied microalgae proved a significant influence on the stability of EPDM, mainly in the presence of SP, which was confirmed by the activation energies calculated from our CL results. The investigation of cycling thermal degradation revealed the obvious contribution of additives towards delaying EPDM ageing.

Palavras-Chave: antioxidants; chlorella; ethylene propylene diene polymers; stability; thermal analysis; radiations

ZAHARESCU, TRAIAN; MATEESCU, CARMEN; DIMA, ANDREEA; VARCA, GUSTAVO H.C. Evaluation of thermal and radiation stability of EPDM in the presence of some algal powders. Journal of Thermal Analysis and Calorimetry, v. 147, n. 1, p. 327-336, 2022. DOI: 10.1007/s10973-020-10319-4. Disponível em: http://repositorio.ipen.br/handle/123456789/32666. Acesso em: $DATA.

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Abstract: One of the methods of protein crosslinking used in the synthesis of protein-based nanoparticles is the formation of bityrosine bridges, which may be achieved by the recombination of phenoxyl-type radicals in irradiated protein solutions. Radiation-induced formation of phenoxyl radicals in tyrosine is promoted in presence of H+. In this work, kinetics of this process and the influence of pH were studied by pulse radiolysis measurements of a model peptide H-Gly-Tyr-Gly-OH (GYG), which may help to solve questions raised for bigger, more complex systems in comparable conditions. The main route of phenoxyl radicals formation consists of the addition reaction of hydroxyl radical to the phenol ring on the tyrosine side-chain and proton catalyzed water molecule elimination. A similar effect was observed in studies of tripeptide solutions containing phosphate buffer. The presented data include time-resolved optical spectroscopy of transient species formed under pulse electron beam irradiation and a comparison of the kinetics of the phenoxyl radicals formation in samples at various pH and in presence of phosphate buffer. The postulated mechanism and obtained values of rate constants of the formation and decay of transient species were additionally checked by simple probabilistic simulations.

Palavras-Chave: ionizing radiations; radiolysis; tyrosine; proteins

SOWINSKI, SEBASTIAN; VARCA, GUSTAVO H.C.; KADLUBOWSKI, SLAWOMIR; LUGAO, ADEMAR B.; ULANSKI, PIOTR. A mechanistic approach towards the formation of bityrosine in proteins by ionizing radiation: GYG model peptide. Radiation Physics and Chemistry, v. 188, p. 1-8, 2021. DOI: 10.1016/j.radphyschem.2021.109644. Disponível em: http://repositorio.ipen.br/handle/123456789/32383. Acesso em: $DATA.

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Abstract: Bladder cancer (BC) is the tenth most common type of cancer worldwide, affecting up to four times more men than women. Depending on the stage of the tumor, different therapy protocols are applied. Non-muscle-invasive cancer englobes around 70% of the cases and is usually treated using the transurethral resection of bladder tumor (TURBIT) followed by the instillation of chemotherapy or immunotherapy. However, due to bladder anatomy and physiology, current intravesical therapies present limitations concerning permeation and time of residence. Furthermore, they require several frequent catheter insertions with a reduced interval between doses, which is highly demotivating for the patient. This scenario has encouraged several pieces of research focusing on the development of drug delivery systems (DDS) to improve drug time residence, permeation capacity, and target release. In this review, the current situation of BC is described concerning the disease and available treatments, followed by a report on the main DDS developed in the past few years, focusing on those based on mucoadhesive polymers as a strategy. A brief review of methods to evaluate mucoadhesion properties is also presented; lastly, different polymers suitable for this application are discussed.

Palavras-Chave: adhesion; drug delivery; bladder; neoplasms; hydrogels; polymers; therapy

LIMA, CAROLINE S.A. de; VARCA, JUSTINE P.R.O.; ALVES, VICTORIA M.; NOGUEIRA, KAMILA M.; CRUZ, CASSIA P.C.; RIAL-HERMIDA, M. ISABEL; KADLUBOWSKI, SLAWOMIR S.; VARCA, GUSTAVO H.C.; LUGAO, ADEMAR B. Mucoadhesive polymers and their applications in drug delivery systems for the treatment of bladder cancer. Gels, v. 8, n. 9, p. 1-25, 2022. DOI: 10.3390/gels8090587. Disponível em: http://repositorio.ipen.br/handle/123456789/33418. Acesso em: $DATA.

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Abstract: Gamma radiation has been shown particularly useful for the functionalization of surfaces with stimuli-responsive polymers. This method involves the formation of active sites (free radicals) onto the polymeric backbone as a result of the high-energy radiation exposition over the polymeric material. Thus, a microenvironment suitable for the reaction among monomer and/or polymer and the active sites is formed and then leading to propagation to form side-chain grafts. The modification of polymers using high-energy irradiation can be performed by the following methods: direct or simultaneous, pre-irradiation oxidative, and pre-irradiation. The most frequently used ones correspond to the pre-irradiation oxidative method as well as the direct one. Radiation-grafting has many advantages over other conventional methods because it does not require the use of catalyst nor additives to initiate the reaction and usually no changes on the mechanical properties with respect to the pristine polymeric matrix are observed. This chapter is focused on the synthesis of smart polymers and coatings obtained by the use of gamma radiation. In addition, the diverse applications of these materials in the biomedical area are also reported, with focus in drug delivery, sutures, and biosensors.

Palavras-Chave: polymers; functions; functionals; drug delivery; sensors; graft polymers; gamma radiation

PINO-RAMOS, VICTOR H.; RAMOS-BALLESTEROS, ALEJANDRO; LOPEZ-SAUCEDO, FELIPE; LOPEZ-BARRIGUETE, JESUS E.; VARCA, GUSTAVO H.C.; BUCIO, EMILIO. Radiation grafting for the functionalization and development of smart polymeric materials. Topics in Current Chemistry, v. 374, n. 5, p. 1-28, 2016. DOI: 10.1007/s41061-016-0063-x. Disponível em: http://repositorio.ipen.br/handle/123456789/27187. Acesso em: $DATA.

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