ACTIVITY REPORT NEW NANOCOMPOSITES BASED ON BIOCOMPATIBLE POLYMERS AND GRAPHENE FOR DENTAL APPLICATIONS BIOGRAF (230/ )

Transcription

1 ACTIVITY REPORT NEW NANOCOMPOSITES BASED ON BIOCOMPATIBLE POLYMERS AND GRAPHENE FOR DENTAL APPLICATIONS BIOGRAF (230/ ) Project Coordinator Dr. STELA MARIA PRUNEANU

2 Introduction Nowadays, there is an intensive research in the field of dental materials that focuses mainly on the investigation of the improvement of mechanical properties (hardness, traction, bending, compression resistance) and physical (thermal conductivity and diffusivity, contraction to polymerization, absorption and water solubility) of the restorative materials as well as the study of the fundamental aspects related to their composition and chemical structure. With all these intensive studies, it has been found in practice that new approaches are needed to obtain restorative nanocomposite materials with features as close as possible to the constructive ideal. The current trend in composite materials is to minimize the size of the fillers in order to improve the mechanical-physical properties and clinical performance. In modern dentistry, both the early prevention of dental caries and the development of new and effective regenerative materials are being pursued. Though great efforts have been made in promoting the oral hygiene through fluorination of water and periodic dental checks, early prevention of caries is still a challenge in dental and public health. Recent studies have indicated that nanotechnology can offer new strategies in dentistry. Graphene is a two-dimensional material made up of a monolayer of carbon atoms, sp 2 hybridized and arranged in a hexagonal network. Very low concentrations of graphene (0.1-5 wt%) can be used as filler in dental materials, significantly improving their mechanical and antibacterial properties. The results found in the literature show that graphene combined with polymers may produce composite materials with new properties, such as higher stretch resistance, improved elasticity and thermal conductivity. The BIOGRAF research project sought to achieve the following results: a new nanocomposite material with graphene, used in dental restorations a laboratory technology for the production of nanocomposite material 3 ISI papers in high impact ISI Journals a patent application Objective 1 (planned and achieved in 2014) Preliminary studies on the elaboration and implementation of new nanocomposites used in dental restorations A.1.1 Preliminary research on the preparation of graphene nanofillers A.1.2 Testing the reaction conditions for graphene preparation- Part I According to literature, graphene flakes can be prepared by various methods, including: (i) catalytic Chemical Vapor Deposition with induction heating; (ii) chemical route. Both methods were tested, as following described. (i) catalytic Chemical Vapor Deposition with induction heating (CCVD-IH) Graphene flakes were prepared by catalytic Chemical Vapor Deposition with Induction Heating, using MgO as catalyst. Briefly, the catalyst was put into the reaction chamber and the temperature was slowly increased to 1000 C. Methane gas was used as carbon source. After about 30 minutes, the synthesis was stopped and the reaction product was purified in HCl. Finally, the reaction product was washed with distilled water and dried for 24 h. The morphological and structural characterization of graphene flakes was performed by TEM and Raman Spectroscopy. (ii) chemical route Graphene oxide (GO) was prepared in two steps. In the first step, the pre-oxidation of graphite was performed in a warm solution of concentrated sulphuric acid, potassium persulfate and phosphorus pentoxide. The resultant mixture was heated to 100 o C and then left to slowly cool. After several hours, the mixture was

3 carefully diluted with water, filtered and washed until the ph water was neutral. The solid was dried at room temperature overnight. In the second step, a suspension of the pre-oxidized graphite powder mixed with sodium nitrite in sulphuric acid was cooled in an ice-water bath. Potassium permanganate was slowly added to the mixture so the temperature would not reach 20 o C. After more than 10 h, it was slowly warmed to o C, for 2 hours. The reaction was stopped by adding hydrogen peroxide, until no more gas development was observed. The GO product was then suspended in distilled water and dialyzed for 5 days. The solid GO was obtained by lyophilization. Thermally reduced graphene oxide (TRGO) was obtained by thermally reducing graphene oxide. N-doped graphene (N-rGO) was prepared by dispersing GO powder in water for several minutes (by ultrasound). Next, urea was added and the resulted homogeneous solution was stirred at high temperature ( o C), for few hours. The resulting black suspension was filtered, washed with water and then thermally treated under argon at around 600 o C. The morphological and structural characterization of GO, TRGO and N-rGO were investigated by TEM, FTIR Spectroscopy and X-Ray powder Diffraction. A.1.3 Preliminary studies on the synthesis of the bioactive nanofillers and of dimethacrylate polymers, used in the preparation of nanocomposites Various types of nanofillers were synthesized: hydroxylapatite (HA), hydroxylapatite with graphene and gold nanoparticles (HA-Gr-Au), hydroxylapatite with graphene and silver nanoparticles (HA-Gr-Ag) and hydroxylapatite with zirconium (HA-Zr). The nanofillers were characterized by TEM, X-Ray powder Diffraction and Thermogravimetric Analysis. Besides nanofillers the composites also contained polymers with high viscosity and high molecular mass. A.1.4 Experimentation of lab technology for the preparation of new nanocomposites, used in dental restorations- Part I Preliminary experiments regarding the influence of the nanofiller (graphene) on the physico-chemical and mechanical properties of the composites were performed. The experiments proved that the samples with graphene had a higher Young modulus (around 15 GPa), higher hardness and higher bending resistance, compared with the samples without graphene. In addition, the surface homogeneity of the sample prepared with the optimum composition was investigated by Atomic Force Microscopy. A.1.5 Development of in vitro protocols to study cell viability: cytotoxycity and cell apoptosis studies with graphene A.1.6 In vitro biocompatibility studies of graphene samples Part I The cytotoxicity and biocompatibility of graphene samples, prepared by catalytic Chemical Vapor Deposition with Induction Heating or by chemical route, were investigated. Cell viability tests and toxicity tests were performed according to ISO and ISO /2009. Since the toxicity of graphene nanostructures is not well known, the tests were performed using various concentrations of graphene. New protocols, for in vitro testing of graphene were developed. All the biological and cytotoxicity tests were performed in triplicate, using different exposures and time landmarks, to allow a better understanding of the mechanisms. The experimental approaches and the results were disseminated among the PhD and PostDoc students. A.1.7 Technical and economical study for marketing the new materials Partner P3 has tested the market regarding the applicability of the composites with graphene, in dental restorations. The market study was encouraging and demonstrated the need to develop novel materials with better mechanical and anti-bacterial properties. A.1.8 Experimental model -Part I The influence of laser radiation upon the polymerization process of dimethacrylic monomers was studied. Some important parameters for the polymerization reaction were determined, such as the optimum concentration of

4 the reactants (monomer, graphene, bioactive nanofiller), the polymerization time as well as the esthetical characteristics of the final nanocomposite material. The polymerization reaction took place under irradiation with nm wavelengths, for short periods of time (around 60 sec). A.1.9 Disemination of the research results to PhD and PostDoc The PhD students and PostDoc were actively involved in most of the research activities. Conclusions All the activities foreseen within this work-package were accomplished: D1-Synthesis and characterization of bioactive nanofiller, graphene and monomers (FM-12/2014); D2 In vitro testing of graphene (FM -12/2014); D3 Technical and economical study for marketing the new composites (FM-12/2014) 2 ISI papers were submitted for publication 3 papers were presented at International Conference. Objective 2 (planned and achieved in 2015) Preparation and optimization of nanocomposite synthesis. Development of the lab technology for nanocomposite synthesis. A.2.1 Testing the reaction conditions for graphene preparation- Part II Graphene-oxide (GO) and its most encountered derivatives, thermally reduced graphene oxide (TRGO) and nitrogen-doped graphene (N Gr) were chemically/thermally synthesized. After synthesis, they were morphologically and structurally characterized by various techniques, like TEM, UV-Vis, Raman and 13 C MAS solid state NMR. A.2.2 Experimentation of lab technology for the preparation of new nanocomposites, used in dental restorations- Part II The lab technology for the preparation of nanocomposites with graphene oxide, used in dental restoration, was developed. In addition, the structural properties of selected nanocomposites were investigated and compared with those of commercial dental composite. A.2.3 Physico-chemical and mechanical characterization of nanocomposites The absorption and the solubility of nanocomposites in water or artificial saliva were determined. Also, the translucency and the amount of residual monomer released in artificial saliva were obtained. The composite materials showed a different pattern of water absorption over time, depending on the type of dipping solution (water or artificial saliva). In terms of the amount of residual monomers, it was found that the nanocomposite with the highest percentage of graphene oxide had the highest value. Act.2.4 In vitro biocompatibility studies of graphene samples Part II Several biological effects (cytotoxicity, oxidative stress induction, and cellular and mithocondrial membrane alterations) induced by GO, TRGO and N-Gr on human dental follicle stem cells were investigated. Graphene oxide (GO) shows the lowest cytotoxic effect, followed by the nitrogen-doped graphene (N-Gr), while thermally reduced graphene oxide (TRGO) exhibits high cytotoxic effects. Graphene oxide induces oxidative stress without damaging the cell membrane. Nitrogen-doped graphene shows a slight antioxidant activity but at high doses (20 and 40 g/ml) it penetrates through the cell membrane. Both graphene oxide and nitrogen-doped graphene are appropriate for usage in dental nanocomposites.

5 Act.2.5 Experimental model -Part II With the employed experimental set-up it was observed that the polymerization of the composite materials with graphene takes place under the nm laser radiation. When higher wavelengths were used, such as 532 or 650 nm, no proper polymerization was achieved, although the laser power was higher (without changing the laser spot). The polymerization reaction takes place in a short and narrow time interval (60-80 seconds). Act.2.6 Disemination of the research results to PhD students and PostDoc The PhD students and PostDoc were actively involved in most of the research activities. Act.2.7 Disemination of the research results The scientific results obtained were disseminated through presentations at International Conferences and articles published in ISI journals. A.2.8 Optimization of synthesis conditions The lab technology for the preparation of nanocomposites with graphene oxide, used in dental restoration, was optimized. Act.2.9 Biological studies: in vitro assessment of apoptotic cell death Based on the data obtained from the cell viability test, we determined that the dental materials with graphene oxide (GO) were non-toxic to human dental follicle stem cells. Using FACS test it was identified that the cells treated with the composites with GO had a high rate of living cells, which varied from 95.7 to 99.9%. Conclusions All the activities foreseen within this work-package were accomplished: D4- Development of lab technology for the synthesis of nanocomposite with graphene (IT ); D5- Establishing the relationships between the nanocomposites structure and their behaviour in the oral environment (IS ); 2 ISI papers and 3 book-chapters were published 1 ISI paper was submitted for publication 4 papers were presented at International Conferences. Objective 3 (planned and achieved in 2016) Technical documentation. Patent elaboration. Biological studies. A 3.1 Preparation of graphene-based nanofillers and their morphological and structural characterization Due to its low cytotoxic effect, graphene-oxide (GO) was selected for addition in dental materials. After preparation, it was combined with oxidic materials (SiO 2 and ZrO 2 ) and the corresponding composite materials (GO-SiO 2 and GO-ZrO 2 ) were morphologically (TEM) and structurally (XRD; FTIR; UV-Vis) characterized. After that, they were used as nanofillers (in low concentrations) in dental materials. A 3.2 Optimization of graphene oxide synthesis The final parameters and the reaction conditions for graphene oxide synthesis were established. The optimized method was developed. The method ensures the synthesis of graphene oxide having the desired morphological and structural characteristics: thin an nm. A 3.3 Optimization of dental materials synthesis Dental materials with composite materials GO-SiO 2 or GO-ZrO 2 were synthesized and the optimized conditions were established:

6 The optimum ratio between the organic and inorganic fillers was 20/80; In order to fulfill the esthetic requirements, low quantities of GO-SiO 2 or GO-ZrO 2 were used ( wt%); The optimum time for mixing the organic with the inorganic fillers was 8 hours; The optimum photopolymerization time was 40 s. A 3.4 Patent elaboration A patent request was submitted to OSIM: Composite material containing graphene oxide and used for dental restoration b Marioara Moldovan, Stela Pruneanu, Crina Socaci, Marcela-Corina Rosu, Codruta Sarosi, Stanca Cuc, Doina Prodan (OSIM No. A/00902/ ) A 3.5 Finalizing the biological studies (in vitro): experimental model for testing the adhesion of new restorative materials to the dental hard tissues; electron microscopy and optical microscopy on extracted human teeth The study aimed to evaluate the marginal infiltration on extracted teeth. 15 extracted teeth were included in the study. The teeth were divided into 3 groups of five teeth: Group 1 - for cavity filling, a material based on graphene oxide and ZrO 2 (GZ2) was used; Group 2 - for cavity filling, a material based on graphene oxide and SiO 2 (GS4) was used; Group 3 the teeth were filled with a light-curing composite trade as Amelogen Plus (Ultradent Products, Inc. USA). The results indicated a score 0 - lack of marginal infiltration, when restoration was performed with GZ2 composite and the commercial Amelogen Plus (Group 1 and Group 3). In the case of restoration with the GS4 composite, a marginal infiltration was observed (score 1- Group 2). A 3.6 The feasibility study for industrial research - Part I The feasibility study was elaborated by APEL LASER SRL. The study aimed to provide the appropriateness of introducing into production a composite material based on biocompatible polymers and graphene, for dental applications. Act. 3.7 Disemination of the research results to PhD students and PostDoc PhD students and PostDoc were actively involved in most of the research activities. Conclusions All the activities foreseen within this work-package were accomplished: D7- Material/Patent D8- Technical data D9- Biological studies 4 ISI papers were published 1 book-chapter was published 1 Patent was submitted to OSIM (nov. 2016) 4 papers were presented at International Conferences. Objective 4 (planned and achieved in 2017) Realization of the prototype. Testing the prototype. Finalizing the biological studies Act 4.1 Testing the functionality of the product Testing the functionality of the nanocomposite for direct dental restorations was done by providing the dental practitioners with the product for clinical testing. The criteria chosen for the evaluation were: Form of the prototype Application mode

7 Restoration aspect Adhesion to dental hard tissues (early infiltration sign) Wear resistance After the test period, by clinical use, according to the working methodology, we can formulate the following: the duration of application of the nanocomposite material at 37 C in the oral cavity at the polymerization time of 40 seconds is appropriate from the point of view of dental techniques; concerning the consistency of the paste we found that it is homogeneous and is applied lightly on the surface of the graded teeth; the surface texture of the nanocomposite after finishing is uniform and smooth; no obvious changes in the colour of the photopolymerizable nanocomposite material were found. Act 4.2 Realization of prototype The results of the research obtained in the previous stage, Act.3.3 (2016) "Optimization of dental materials synthesis" revealed that SiO 2 / ZrO 2 doped graphene powders (GO: SiO 2 _T and GO: ZrO 2 _T) gave the best physico-chemical and mechanical properties of the experimental nanocomposite materials, in which composition they were introduced. It has been established that the optimal percentage of graphene to be introduced so that the nanocomposite material retains the appropriate aesthetic properties is 0.2%. Act 4.3 The demonstration of the prototype functionality by establishing the relationships between its characteristics and in vitro/vivo behaviour The biocompatibility and toxicity of the nanocomposite was evaluated by introducing a small amount of nanocomposite into the bone defect (size: h = 1 mm and d = 2 mm) created with a dental cut into the mandible bone. The test was performed on a Wistar male rat, aged 6 months. This study involving the use of laboratory animals in disease-causing protocols has been carried out with strict adherence to the regulations required by national legislation (Law 43/2014) and European (Directive 63/2010) on the use of animals in experimental procedures for scientific purposes. At the end of the experimental period, there was an appreciation of the local changes at the implant site, their impact on the general condition of the animal and the relationship between the mandible bone and the implant material. Act. 4.4 Performing the Feasibility Study for Industrial Research - Part II The PRODUCT SHEET for the nanocomposite "BIOGRAF" based on biocompatible polymers and graphene, used for dental restorations was obtained. Act. 4.5 Dissemination of the research results at doctoral and post-doctoral level Research on the use of graphene in dental nanocomposite materials was presented to PhD and post-doctoral students participating in the project. Act. 4.6 Participation in technical-scientific events in specific project areas The scientific results obtained were disseminated through presentations at International Conferences and articles published in ISI journals. Conclusions All the activities foreseen within the work-package were accomplished: D 6- Testing the functionality of the product to be promoted ( ); D 9- Completion of Biological Studies (IS-09/2017); One ISI paper was published; two are under evaluation; 11 contributions were presented at International Conferences. The impact of the obtained results, emphasizing the most significant result obtained Within the "BIOGRAF" project, the technological parameters for obtaining a new nanocomposite material based on biocompatible polymers and graphene usable in dental restorations were optimized and

8 finalized. The laboratory technology was developed. The product sheet and the presentation manual called "BIOGRAF" were prepared according to the objectives of the project. GENERAL CONCLUSIONS The BIOGRAF research project has produced the following results: A w o om o m w graphene, used in dental restorations A laboratory technology for the synthesis of the nanocomposite material 9 ISI papers, in high impact ISI Journals (two under evaluation) A patent application 22 Presentations at National / International Conferences 4 book-chapters A National Award Dissemination of the results ISI papers: 1. F. Pogacean, C. Socaci, S. Pruneanu, A.R. Biris, M. Coros, L. Magerusan, G. Katona, R. Turcu, G. Borodi, Graphene based nanomaterials as chemical sensors for hydrogen peroxide A comparison study of their intrinsic peroxidase catalytic behavior, Sensors and Actuators B 213 (2015) (IF 4.758) 2. D. Olteanu, A. Filip, C. Socaci, A. R. Biris, X. Filip, M. Coros, M. C. Rosu, F. Pogacean, C. Alb, I. Baldea, P. Bolfa, S. Pruneanu, Cytotoxicity assessment of graphene-based nanomaterials on human dental follicle stem cells, Colloids and Surfaces B: Biointerfaces 136 (2015) (IF 3.902) 3. C. Socaci, F. Pogacean, A.R. Biris, M. Coros, M.C. Rosu, L. Magerusan, G. Katona, S. Pruneanu, Graphene oxide vs. reduced graphene oxide as carbon support in porphyrin peroxidase biomimetic nanomaterials, Talanta, 148 (2016) (IF 4.162) 4. M.C. Rosu, C. Socaci, V. Floare-Avram, G. Borodi, F. Pogacean, M. Coros, L. Magerusan, S. Pruneanu, Photocatalytic performance of graphene/tio 2 -Ag composites on amaranth dye degradation, Materials Chemistry and Physics 179 (2016) (IF 2.082) 5. A. Muntean, A. Mesaros, D. Festila, M. Moldovan, M. Mesaros, In Vitro Microleakage Evaluation Around Three Types of Dental Sealants, Materiale Plastice, Vol.53, No.1 (2016) (IF 0.778) 6. C. Sarosi, A.R. Biris, A. Antoniac, S. Boboia, C. Alb, I. Antoniac, M. Moldovan, The nanofiller effect on properties of experimental graphene dental nanocomposites, Journal of Adhesion Science and Technology, VOL. 30, NO. 16 (2016) (IF 1.073) 7. M. Co oş, F. Pog, L. M g uş, M.C. Roşu, A.S. Po v, C. So, A. B, R.I. S f -van Staden, and S. Pruneanu, Graphene-porphyrin composite synthesis through graphite exfoliation: the electrochemical sensing of catechol, Sensors and Actuators B- Chemical in evaluation September 2017 (IF 5.401) 8. M. Moldovan, D. Prodan, C. Sarosi, R. Carpa, C. Socaci, M-C. Rosu, S. Pruneanu, Synthesis, morphostructural properties and antibacterial effect of silicate-based composites containing graphene oxide/hydroxyapatite, submitted to Materials Chemistry and Physics, Sept 2017 (IF 2.048) 9. A.Muntean, A. S. Mesaros, A. Porumb, S. Cuc, M. Moldovan, A. Balan, Enamel Appearance after Orthodontic Attachment Removal, In vitro SEM analysis, REV.CHIM. (Bucharest), 68 (2017) (IF 1.232)

9 International Conferences 1. C. Sarosi, S. Pruneanu, V. Simon, D. Prodan, S. Boboia, C. Alb, S. Sava, A. Antoniac, M. Moldovan, The nanofiller effect on properties of experimental graphene dental nanocomposites, 6th International Co f B om, T u E g g & M D v B omm D 0 4-Constanta, oral presentation 2. S. Alb, D. Dudea, A. Mesaros, A. Grecu, M. Manole, C. Alb, Use of Modern Communication Methods by Central European Dentists, J. Dent Res 93 (Spec Iss C), 2014 ( IADR/PER Congress 2014, September 2014, Dubrovnik, Croatia- poster 3. C. Alb, A. Mesaros, D. Dudea, P. Buiga, C. Gasparik, S. Alb, Analysis of Maxilary anterior teeth in a young population, J. Dent Res 93 (Spec Iss C), 2014 ( IADR/PER Congress 2014, September 2014, Dubrovnik, Croatia- poster 4. M. Coros, F. Pogacean, M.C. Rosu, C. Socaci, G. Borodi, A.R. Biris, D.N. Becherescu Barbu, S. Pruneanu, Synthesis of graphene oxide by electrochemical exfoliation of graphite- 10 th biennial International Conference on Processes in Isotopes and Molecules (PIM 2015), September 2015, Cluj-Napoca, Romania- poster 5. C. Sarosi, M.C. Rosu, L. Silaghi-Dumitrescu, V. Prejmerean, M. Moldovan, Comparative translucency of graphene-silica experimental nanocomposites and esthetic composite materials, SCAD 2015 Annual Conference, September , Chicago, USA- poster 6. C. Sarosi, S. Pruneanu, S. Boboia, M. Filip, C. Alb, M. Moldovan, The nanofiller effect on the residual monomers amount of the graphene dental nanocomposites, Simpozion Napoca Biodent 2015, March 2015, Cluj-Napoca, Romania- poster 7. C. Sarosi, M.C. Rosu, S. Boboia, M. Filip, D. Prodan, C. Prejmerean, C. Alb, M. Moldovan, The evaluation of water sorbtion/solubility and monomer release on graphene dental nanocomposites, International Seminar on Biomaterials and Regenerative Medicine, September , Oradea, Romania- poster 8. M.C. Rosu, C. Socaci, L. Magerusan, F. Pogacean, M. Coros, E. Pall, S. Pruneanu, Graphene oxide-based composites as biocompatible substrates for cell adhesion and proliferation, CNB 2016, National Conference of Biophysics, June 2-4, 2016, Cluj-Napoca, Romania- poster 9. S. Pruneanu, C. Socaci, F. Pogacean, M. Coros, L. Magerusan, M.C. Rosu, - Peroxidase biomimetic materials based on porphyrin and graphene/graphene oxide, CNB 2016, National Conference of Biophysics, June 2-4, 2016, Cluj-Napoca, Romania- poster 10. M.C. Rosu, C. Prejmerean, L. Silaghi-Dumitrescu, S. Cuc, D. Prodan, M. Moldovan C. Sarosi, The effect of different drinks on the color stability of graphene experimental nanocomposites, International Symposium of Dentistry Napoca Biodent 2016, 9-10th May 2016, Cluj-Napoca, Romania Oral presentation 11. C. Sarosi, M.C. Rosu, C. Prejmerean, L. Silaghi-Dumitrescu, M. Moldovan, Color change of some experimental nanocomposites after accelerated aging test SCAD 2016: 8 th Annual Conference of Society for Color and Appearance in Dentistry Chicago, IL, September poster 12. M.C. Rosu, M. Moldovan, C. Socaci, S. Pruneanu, D. Prodan, C. Sarosi, R. Carpa, Silica-based materials containing graphene oxide / hydroxyapatite with antibacterial activity against E. coli and S. aureus bacteria, 2 nd International Conference on Chemical and Biochemical Engineering, Canary Island, Spain, July, poster 13. M. Coros, F. Pogacean, M.C. Rosu, L. Magerusan, C. Socaci, A. Turza, S. Pruneanu, Graphene-gold nanoparticles composites: Synthesis and application, International Conference on Processes in Isotopes and Molecules (PIM 2017), September 2017, Cluj-Napoca, Romania - poster 14. S. Pruneanu, F. Pogacean, M. Coros, L. Magerusan, M. C. Rosu, C. Socaci, A. Turza, Graphene synthesis through electrochemical exfoliation of graphite rod, International Conference on Processes in Isotopes and Molecules (PIM 2017), September 2017, Cluj-Napoca, Romania Oral presentation

10 15. S. Pruneanu, F. Pogacean, M. Coros, C. Socaci, L. Magerusan, M.C. Rosu, Electrochemical detection of various organic molecules using graphene-modified electrodes, Workshop on Integrated Nanodevices for Environmental Analysis, 26 May 2017, Technical University, Cluj-Napoca Oral presentation 16. C. Berghian-Grosan, A. Vulcu, A. R. Biris, G. Borodi, S. Pruneanu, Dopamine Adsorption on Graphene-based Composite: Electrochemical and Raman Spectroscopic Investigations International Conference on Processes in Isotopes and Molecules (PIM 2017), September 2017, Cluj-Napoca, Romania poster 17. M. D. Lazar, M. Mihet, A. Vulcu, M. Dan, Graphene oxide metal nanoparticle composites: preparation and characterization, International Conference on Processes in Isotopes and Molecules (PIM 2017), September 2017, Cluj-Napoca, Romania, -poster 18. C. Sarosi, M-C. Rosu, C. Gasparik, C. Prejmerean, D. Prodan, L. Silaghi-Dumitrescu, M. Moldovan, Evaluation of restoration interface microleakage of experimental graphene oxide composites, FDI World Dental Congress, 29 August -1 September 2017, Madrid, Spain- poster 19. M. Moldovan, S.Pruneanu, C. Sarosi, D. Prodan, L. Silaghi-Dumitrescu, M. Filip, The structure, properties and susceptibility of the nanocomposites with graphene oxide, used in dentistry, ANM st International Conference on Advanced Polymer Materials and Nanocomposites, July 2017, Aveiro, Portugal- poster 20. C. Sarosi, S. Pruneanu, C. Gasparik, D. Prodan, C. Prejmerean, L.Silaghi-Dumitrescu, M. Moldovan, Marginal microleakage of teeth restorations with graphene oxide experimental composites, COST Action MP NEWGEN - New Generation Biomimetic and Customized Implants for Bone Engineering, Working Groups and Scientific Workshop Biomaterials for Dental and Orthopedic Applications, March, Cluj Napoca, Romania- poster 21. M. Filip, M. Vlassa, L. Silaghi-Dumitrescu, D. Prodan, M. Moldovan, Quantification monomers elution and residual double bonds of some lightcuring dental composites using HPLC and FTIR spectroscopy, Napoca Biodent Symposium 2017, 7 th Edition, Research in Dentistry- Quo Vadis- Oral presentation 22. L. Silaghi-Dumitrescu, D. Prodan, C. Prejmerean, C. Sarosi, M. Filip, M. Moldovan, Effect of artificial saliva and water on experimental restorative composites, Napoca Biodent Symposium 2017, 7 th Edition, Research in Dentistry- Quo Vadis- Oral presentation Book chapters 1. S. Pruneanu, M. Coros, F. Pogacean, Bio-Functionalized Metallic Nanoparticles with Applications in Medicine, Handbook of Nanoparticles, Springer International Publishing, 2015, DOI / _36-1, C. Sarosi, M.C. Rosu, S. Boboia, M. Filip, C. Alb, M. Moldovan, Efectul nanoparticulelor asupra cantității de monomer rezidual la nanocompozitele cu grafene, Editura Colorama, ISBN , 2015, L. Silaghi-Dumitrescu, D. Prodan, G. Furtos, A. Roman, V. Prejmerean, M. Moldovan, Proprietati optice ale materialelor compozite, Editura Colorama, ISBN , 2015, C. Sarosi, M.C. Rosu, C. Prejmerean, L. Silaghi-Dumitrescu, S. Cuc, D. Prodan, M. Moldovan, Efectul diferitelor bauturi asupra stabilitatii culorii nanocompozitelor experimentale cu grafene, pg , 2016, in Cercetarea in Medicina dentara- proprietati optice ale dintilor si materialelor dentare, Colorama- Cluj-Napoca; ISBN

11 Patent application 1. M. Moldovan, S. Pruneanu, C. Socaci, M. C. Rosu, C. Sarosi, S. Cuc, D. Prodan, A. G. Filip, Composite material with graphene oxide for dental restorations OSIM- A/00902/ National Award 1. Diploma of Excellence and Gold Medal at the International Salon of Research, Innovation and Inventions, PRO INVENT- XV Edition , Cluj-Napoca, Romania, M. Moldovan, S. Pruneanu, C. Socaci, M. C. Rosu, C. Sarosi, S. Cuc, D. Prodan, Composite material with graphene oxide for dental restorations