Untitled

Funder

Organizational Unit

Publications

Does surface charge play a role in nanoparticulate-systems toxicity?

Publication . Bettencourt, A.; Graça, D.F.; Ferreira, IFS; Matos, A.; Louro, Henriqueta; Silva, Maria João; Almeida, A.J.; Gonçalves, L.M.

The aim of the present work was to compare the toxicity of relevant biomedical acrylic based particulate systems (polymethylmethacrylate – PMMA), with different charges, within the same size range (500nm). Specifically, PMMA (negatively charged) and PMMA-Eudragit (positively charged) formulations were considered.

2015-02Conference object

Open access

Safety evaluation of novel polymeric nanocarriers for drug delivery using human osteoblasts

Publication . Dias, Kamila; Louro, Henriqueta; Gonçalves, Lídia; Bettencourt, Ana; Silva, Maria João

The development of novel nanocarriers has been recognized as a promising approach to improve drug release profiles on targeted sites, being the assessment of their biocompatibility and safety a critical point of the process. The objective of this work was to characterize the cellular interactions and the potential toxicity of the novel developed polymeric nanoparticles (NPs), using human osteoblasts. For this purpose, Poly(methyl methacrylate) (PMMA) and PMMA-Eudragit RL 100 (PMMA-Eud, 50:50) NPs were produced and their physicochemical properties were characterized. The safety evaluation of both NPs was conducted through the characterization of cellular uptake (fluorescence microscopy), cyto- and genotoxicity (MTT, Comet and Micronucleus assays) using both normal and differentiated osteoblast cell line (MG-63-ATCC®CRL-1427™). The results confirmed the successful uptake of PMMA and PMMA-Eud by the cells. Both NPs were not cytotoxic in differentiated cells, although a moderate toxicity was detected in undifferentiated cells. As to their genotoxic potential, NPs induced primary DNA damage in osteoblasts, especially under a short-term exposure. Noteworthy, none of the NPs caused chromosome breaks, indicating that the primary DNA lesions were not converted into permanent genetic damage. On the other hand, an increased cell proliferative capacity was noted for PMMA-NPs, which deserves further investigation. In conclusion, the safety assessment of the two NPs indicated that both are biocompatible but display a weak genotoxicity that should be explored in other in vitro endpoints, e.g., gene mutation, and in vivo studies. Moreover, understanding how physicochemical features relate to toxicity will support the design of safer formulations for biomedical purposes.

2017-05-08Conference object

Restricted access

Toxicity screening of a novel poly(methylmethacrylate)-Eudragit nanocarrier on L929 fibroblasts

Publication . Graça, Diogo; Louro, Henriqueta; Santos, Joana; Dias, Kamila; Almeida, Antonio J; Gonçalves, Lídia; Silva, Maria João; Bettencourt, Ana

Translation of innovative drug delivery nanosystems into the market involves an early toxicity screening in the development phase. Previously, we showed that inclusion of the polymer Eudragit (EUD) into poly(methylmethacrylate) (PMMA) nanoparticles (NP) resulted in a novel nanocarrier (PMMA-EUD) with an improved biomedical performance. The safety of this novel nanoparticulate system (PMMA-EUDNPs) was assessed in this work and compared to that of the original PMMANPs by using an integrated approach, comprising in vitro toxicity assessment and NPs physicochemical characterization in water and cell medium. For toxicity assessment several endpoints were analysed, including cell death, oxidative stress, and genotoxicity using L929 fibroblasts. PMMA-EUDNPs proved to be more hydrophobic than the original PMMANPs. Also, charge of both NPs was strongly affected by cell medium. On the other hand, the novel nanosystem was easily uptaken by L929 cells and did not display relevant in vitro cytotoxic or genotoxic effects. On the contrary, PMMANPs were less internalized in cells and proved to be genotoxic, as measured by the micronucleus assay. To conclude, our results provide initial evidence about the safety of the novel and promising PMMA-EUD nanoparticulate system, enabling its further development towards applications for drug delivery.

2017-07-05Journal article

Restricted access

Biocompatibility Assessment of Polymeric Nanoparticle Carriers for Drug Delivery in Human Osteoblasts

Publication . Dias, Kamila; Louro, Henriqueta; Gonçalves, Lídia; Silva, Maria João; Bettencourt, Ana

Bone infections after prosthetic surgery represent a painful and costly process that should be prevented. The use of nanocarriers as efficient drug-delivery systems represents an innovative strategy to reduce systemic toxicity and avoid antimicrobial resistance. Still, great efforts are required to ensure the biocompatibility and safety of new nanocarriers before their medical application. In this work, the FDA-approved polymers poly(methyl methacrylate) (PMMA), and Eudragit RL 100 (Eud) were used to obtain two sets of nanoparticles, plain PMMA and PMMA-Eud (50:50). Their biocompatibility was assessed in a normal and differentiated human osteoblast cell line. The nanoparticles synthesis was conducted by a previously optimized methodology and their physicochemical properties, including size distribution, surface charge, morphology and aggregation/agglomeration states, were analysed during different preparation steps. Furthermore, the cell uptake and cytotoxicity as well as and their potential to produce reactive oxygen species (ROS) were also studied. Cell assays were performed following exposure of MG63 (ATCC®CRL-1427™) under normal and differentiation culture conditions, to a concentration range of both polymeric nanoparticles. The results of the uptake studies confirmed that both nanoparticles are internalized by osteoblasts. For both formulations, neither a significant decrease in cell viability nor oxidative stress induction was observed. The comparative analysis of data obtained in undifferentiated osteoblast and in those under differentiation conditions showed similar effects being the latter slightly less sensitive to the nanoparticles toxicity. Based on the reported data, PMMA and PMMA-Eud can be described as biocompatible nanomaterials and be further explored in a perspective of potential carriers for drug delivery, reducing adverse effects of conventional treatments. However, another key property i.e., genotoxicity, needs to be assessed before ensuring their safety for human health. This approach isn’t only relevant for understanding the nano-bio interface by disclosing how physicochemical features relate to toxicological events, but also to support the safe-by-design concept.

2017-05Conference object

Restricted access

Assessing the Safety of Polymeric Nanoparticulated Systems developed for Drug Delivery with Human Osteoblasts

Publication . Dias, Kamila; Louro, Henriqueta; Gonçalves, Lídia; Bettencourt, Ana; Silva, Maria João

The development of novel nanocarriers has been recognized as a promising approach to improve drug release profiles within the target sites, being the assessment of their biocompatibility and safety a critical point of the process. For this purpose, Poly(methyl methacrylate) (PMMA) and PMMA-Eudragit RL 100 (PMMA-Eud, 50:50) nanoparticles (NPs) were recently produced to target bone infections following prosthetic surgeries and a first toxicity screening on fibroblats was conducted. The objective of the present work was to further characterize the cellular interactions and the potential toxicity of those polymeric NPs, using human osteoblasts. PMMA and PMMA-Eud (50:50) NPs were produced by single emulsion evaporation methodology and their physicochemical properties (size distribution, surface charge, morphology and aggregation/agglomeration states) were assessed. Their safety was evaluated both in normal and differentiated MG63 cells through studies of cell uptake, cyto- and genotoxicity using several endpoints: cell viability, oxidative stress production, DNA and chromosome damage. The successful cellular uptake of PMMA and PMMA-Eud by osteoblast was confirmed. None of the NPs was cytotoxic or induced oxidative stress in differentiated cells, although a moderated toxicity was detected in undifferentiated cells. As to the genotoxic potential, both NPs induced primary DNA damage detected by the comet assay, especially in short-term exposure. Noteworthy, none of the NPs caused chromosome breakage/loss using the micronucleus assay that is recommended by OECD/ICH testing guidelines for pharmaceuticals. Our findings suggest that, despite PMMA and PMMA-Eud are promising nanocarriers for drug delivery, the primary genotoxicity observed in osteoblasts needs to be further investigated. In addition, the fact that NPs affect differently normal and differentiated osteoblasts suggests the need of using more sophisticated in vitro cellular systems to better mimic the complexity of the target tissues and thus minimize the utilization of in vivo models.

2018-01-25Conference object

Restricted access