Browsing by Author "Almeida, António J."
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- Levofloxacin-loaded bone cement delivery system: highly effective against intracellular bacteria and Staphylococcus aureus biofilmsPublication . Ferreira, Magda; Rzhepishevska, Olena; Grenho, Liliana; Malheiros, Danila; Gonçalves, Lídia; Almeida, António J.; Jordao, Luisa; Ribeiro, Isabel A.; Ramstedt, Madeleine; Gomes, Pedro; Bettencourt, AnaStaphylococcus aureus is a major pathogen in bone associated infections due to its ability to adhere and form biofilms on bone and/or implants. Moreover, recrudescent and chronic infections have been associated with S. aureus capacity to invade and persist within osteoblast cells. With the growing need of novel therapeutic tools, this research aimed to evaluate some important key biological properties of a novel carrier system composed of acrylic bone cement (polymethylmethacrylate - PMMA), loaded with a release modulator (lactose) and an antibiotic (levofloxacin). Levofloxacin-loaded bone cement (BC) exhibited antimicrobial effects against planktonic and biofilm forms of S. aureus (evaluated by a flow chamber system). Moreover, novel BC formulation showed high anti-bacterial intraosteoblast activity. This fact led to the conclusion that levofloxacin released from BC matrices could penetrate the cell membrane of osteoblasts and be active against S. aureus strains in the intracellular environment. Furthermore, levofloxacin-BC formulations showed no significant in vitro cytotoxicity and no allergic potential (measured by the in vivo chorioallantoic membrane assay). Our results indicate that levofloxacin-loaded BC has potential as a local antibiotic delivery system for treating S. aureus associated bone infections.
- Role of nanogenotoxicology studies in safety evaluation of nanomaterialsPublication . Louro, Henriqueta; Bettencourt, Ana; Gonçalves, Lídia M.; Almeida, António J.; Silva, Maria JoãoNanomaterials (NMs) are defined as materials containing particles where one or more external dimensions are in the size range of 1 100 nm. Many different NMs, alone or in combination,in the form of fibers, tubes, or particles have been already proposed for innovative diagnostic, drug delivery platforms and nanostructured matrices for tissue engineering applications. Presently, the diversity of NMs that are being used, or explored as candidates, for tissue engineering can be classified into different groups (polymers, ceramics,carbon nanotubes [CNTs], metals and composites), depending on their chemical composition. This chapter describes the importance of genotoxicity evaluation to warrant the safety of these innovative NMs, with particular emphasis on the most prominent testing strategies that must consider and incorporate the specific physicochemical characteristics of the nanosized materials into toxicological research.