Metabolomic response of osteosarcoma cells to nanographene oxide-mediated hyperthermia.

Nanographene oxide (nGO)-mediated hyperthermia has been increasingly investigated as a localized, minimally invasive anticancer therapeutic approach. Near InfraRed (NIR) light irradiation for inducing hyperthermia is particularly attractive, because biological systems mostly lack chromophores that absorb in this spectral window, facilitating the selective heating and destruction of cells which have internalized the NIR absorbing-nanomaterials. However, little is known about biological effects accompanying nGO-mediated hyperthermia at cellular and molecular levels. In this work, well-characterized pegylated nGO sheets with a hydrodynamic size of 300 nm were incubated with human Saos-2 osteosarcoma cells for 24 h and their internalization verified by flow cytometry and confocal microscopy. No effect on cell viability was observed after nGO uptake by Saos-2 cells. However, a proliferation delay was observed due to the presence of nGO sheets in the cytoplasm. 1H NMR metabolomics was employed to screen for changes in the metabolic profile of cells, as this could help to improve understanding of cellular responses to nanomaterials and provide new endpoint markers of effect. Cells internalizing nGO sheets showed noticeable changes in several metabolites compared to control cells, including decreased levels of several amino acids, taurine and creatine and increased levels of phosphocholine and uridine/adenosine nucleotides. After NIR irradiation, cells showed decreases in glutamate and uridine nucleotides, together with increases in glycerophosphocholine and adenosine monophosphate. Overall, this study has shown that the cellular metabolome sensitively responded to nGO exposure and nGO-mediated hyperthermia and that NMR metabolomics is a powerful tool to investigate treatment responses.

Multifunctional pH sensitive 3D scaffolds for treatment and prevention of bone infection.

Multifunctional-therapeutic three-dimensional (3D) scaffolds have been prepared. These biomaterials are able to destroy the S. aureus bacterial biofilm and to allow bone regeneration at the same time. The present study is focused on the design of pH sensitive 3D hierarchical meso-macroporous 3D scaffolds based on MGHA nanocomposite formed by a mesostructured glassy network with embedded hydroxyapatite nanoparticles, whose mesopores have been loaded with levofloxacin (Levo) as antibacterial agent. These 3D platforms exhibit controlled and pH-dependent Levo release, sustained over time at physiological pH (7.4) and notably increased at infection pH (6.7 and 5.5), which is due to the different interaction rate between diverse Levo species and the silica matrix. These 3D systems are able to inhibit the S. aureus growth and to destroy the bacterial biofilm without cytotoxic effects on human osteoblasts and allowing an adequate colonization and differentiation of preosteoblastic cells on their surface. These findings suggest promising applications of these hierarchical MGHA nanocomposite 3D scaffolds for the treatment and prevention of bone infection. STATEMENT OF SIGNIFICANCE: Multifunctional 3D nanocomposite scaffolds with the ability for loading and sustained delivery of an antimicrobial agent, to eliminate and prevent bone infection and at the same time to contribute to bone regeneration process without cytotoxic effects on the surrounding tissue has been proposed. These 3D scaffolds exhibit a sustained levofloxacin delivery at physiological pH (pH 7.4), which increasing notably when pH decreases to characteristic values of bone infection process (pH 6.7 and pH 5.5). In vitro competitive assays between preosteoblastic and bacteria onto the 3D scaffold surface demonstrated an adequate osteoblast colonization in entire scaffold surface together with the ability to eliminate bacteria contamination.