Extensive Investigation on the Effect of Niobium Insertion on the Physical and Biological Properties of 45S5 Bioactive Glass for Dental Implant

Funding Information: This research was funded by FEDER funds through the COMPETE 2020 Program and National Funds through FCT—Portuguese Foundation for Science and Technology under the project LISBOA-01-0247-FEDER-039985/POCI-01-0247-FEDER-039985, LA/P/0037/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication—i3N, UIDP/04378/2020 and UIDB/04378/2020 of the Research Unit on Applied Molecular Biosciences—UCIBIO, and LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy—i4HB. S.K. Jakka acknowledges FCT—Fundaçao para a Ciência e a Tecnologia, Portugal, I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of article 23 of the Decree Law 57/2016 of 29 August, changed by Law 57/2017 of 19 July. Publisher Copyright: © 2023 by the authors.Dental implants have emerged as one of the most consistent and predictable treatments in the oral surgery field. However, the placement of the implant is sometimes associated with bacterial infection leading to its loss. In this work, we intend to solve this problem through the development of a biomaterial for implant coatings based on 45S5 Bioglass® modified with different amounts of niobium pentoxide (Nb2O5). The structural feature of the glasses, assessed by XRD and FTIR, did not change in spite of Nb2O5 incorporation. The Raman spectra reveal the Nb2O5 incorporation related to the appearance of NbO4 and NbO6 structural units. Since the electrical characteristics of these biomaterials influence their osseointegration ability, AC and DC electrical conductivity were studied by impedance spectroscopy, in the frequency range of 102–106 Hz and temperature range of 200–400 K. The cytotoxicity of glasses was evaluated using the osteosarcoma Saos-2 cells line. The in vitro bioactivity studies and the antibacterial tests against Gram-positive and Gram-negative bacteria revealed that the samples loaded with 2 mol% Nb2O5 had the highest bioactivity and greatest antibacterial effect. Overall, the results showed that the modified 45S5 bioactive glasses can be used as an antibacterial coating material for implants, with high bioactivity, being also non-cytotoxic to mammalian cells.publishersversionpublishe

Biocomposite macrospheres based on strontium-bioactive glass for application as bone fillers

Traditional bioactive glass powders are typically composed of irregular particles that can be packed into dense configurations presenting low interconnectivity, which can limit bone ingrowth. The use of novel biocomposite sphere formulations comprising bioactive factors as bone fillers are most advantageous, as it simultaneously allows for packing the particles in a 3-dimensional manner to achieve an adequate interconnected porosity, enhanced biological performance, and ultimately a superior new bone formation. In this work, we develop and characterize novel biocomposite macrospheres of Sr-bioactive glass using sodium alginate, polylactic acid (PLA), and chitosan (CH) as encapsulating materials for finding applications as bone fillers. The biocomposite macrospheres that were obtained using PLA have a larger size distribution and higher porosity and an interconnectivity of 99.7%. Loose apatite particles were observed on the surface of macrospheres prepared with alginate and CH by means of soaking into a simulated body fluid (SBF) for 7 days. A dense apatite layer was formed on the biocomposite macrospheresâ surface produced with PLA, which served to protect PLA from degradation. In vitro investigations demonstrated that biocomposite macrospheres had minimal cytotoxic effects on a human osteosarcoma cell line (SaOS-2 cells). However, the accelerated degradation of PLA due to the degradation of bioactive glass may account for the observed decrease in SaOS-2 cells viability. Among the biocomposite macrospheres, those composed of PLA exhibited the most promising characteristics for their potential use as fillers in bone tissue repair applications.This work was funded by grant #2019/15960-6, São Paulo Research Foundation in Brazil (FAPESP) and the Portuguese Foundation for Science and Technology (FCT), Reference UID/CTM/50025/2019 and FCT/Minister of Science, Technology and Higher Education in Portugal (MCTES) and by European Regional Development Fund (FEDER) funds through the COMPETE 2020 Program in the framework of ORAiDEA project (ref n° 39985 - AAC 31/SI/2017). The authors would also like to acknowledge Materials Research Center (CENIMAT) of the Associated Laboratory Institute of Nanostructures, Nanomodeling and Nanofabrication (i3N), NOVA University of LisbonCENIMAT|i3N and National Council for Scientific and Technological Development in Brazil CNPq (303149/2018-3). Ibrahim Fatih Cengiz acknowledges the FCT distinction attributed to him under the “Estímulo ao Emprego Científico” program (2021.01969.CEECIND). The authors thank the financial support provided under the projects: “HEALTH-UNORTE: Setting-up biobanks and regenerative medicine strategies to boost research in cardiovascular, musculoskeletal, neurological, oncological, immunological, and infectious diseases”, reference NORTE-01-0145-FEDER-000039, funded by the Norte Portugal Regional Coordination and Development Commission (CCDR-N), under the NORTE2020 Program; Projects LA/P/0037/2020, UIDP/50025/2020, and UIDB/50025/ 2020 of the Associate Laboratory i3N financed by national funds from FCT

Nanostructured LiFe5O8 by a biogenic method for applications from electronics to medicine

The authors are grateful for the FEDER funds through the COMPETE 2020 Program and National Funds through FCT-Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2019, and Romanian Ministry of Education and Research, under Romanian National Nucleu Program LAPLAS VI.The physical properties of the cubic and ferrimagnetic spinel ferrite LiFe5O8 has made it an attractive material for electronic and medical applications. In this work, LiFe5O8 nanosized crystallites were synthesized by a novel and eco-friendly sol-gel process, by using powder coconut water as a mediated reaction medium. The dried powders were heat-treated (HT) at temperatures between 400 and 1000◦C, and their structure, morphology, electrical and magnetic characteristics, cytotoxicity, and magnetic hyperthermia assays were performed. The heat treatment of the LiFe5O8 powder tunes the crystallite sizes between 50 nm and 200 nm. When increasing the temperature of the HT, secondary phases start to form. The dielectric analysis revealed, at 300 K and 10 kHz, an increase of ε′ (≈10 up to ≈14) with a tan δ almost constant (≈0.3) with the increase of the HT temperature. The cytotoxicity results reveal, for concentrations below 2.5 mg/mL, that all samples have a non-cytotoxicity property. The sample heat-treated at 1000◦C, which revealed hysteresis and magnetic saturation of 73 emu g−1 at 300 K, showed a heating profile adequate for magnetic hyperthermia applications, showing the potential for biomedical applications.publishersversionpublishe