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Aim: The low solubility and consequent poor bioavailability of ibuprofen (IBU) is a major drawback that can be overcome by anchoring IBU on ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) as effective multifunctional carriers for drug delivery. Methods: USPIONs were conjugated with glycerol phosphate (USPION-GP) and also co-conjugated with IBU (USPION-GP/IBU), and their in vivo toxicity and anti-inflammatory effects investigated. Phosphate buffer saline (control), IBU, USPION-GP and USPION-GP/IBU were intravenously administered 15 min before lipopolysaccharide-induced peritonitis in male Balb/c mice. Results: 4 h later, USPION bioconjugates did not appear to have caused toxicity to blood leukocytes or caused alterations in the spleen, liver or kidneys. Also, they inhibited lipopolysaccharide-induced neutrophil mobilization into the peritoneum. Conclusion: The absence of systemic toxicity and the unexpected anti-inflammatory action of USPION bioconjugates indicates that they could be a novel and effective approach to administer IBU and warrant further investigation.

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A systematic study was carried out to evaluate the uptake and cytotoxicity of methotrexate (MTX) conjugated to superparamagnetic iron oxide nanoparticles (SPIONs) modified with glycerol phosphate (Glyc) and phosphorylethanolamine (PEA), using MCF-7 cancer cell line as model. The ligand shell composition was controlled in such a way to get SPIONs with nine different surface functionalization and up to three co-conjugated ligands but the very iron oxide core, in order to test and compare uptake and cytotoxicity, and verify possible additive effects. Folic acid (FA), the non-toxic analogue of MTX, was also explored as ligand for SPIONs. Glyc was shown to enhance dramatically the cellular uptake despite the high negative zeta potentials, whereas PEA, FA and MTX was found to have a much lower effect on the cellular uptake. Also, a significant ten times lowering of IC50 was observed for the co-conjugated MTX in the SPION-Glyc/PEA/MTX as compared to the free drug, whereas the analogue SPION-Glyc/PEA/FA nanoparticles exhibited no significant cytotoxicity. In short, the conjugation of MTX to SPIONs enhanced dramatically its cytotoxicity and decreased the IC50 value against MCF-7 tumor cells as compared to the free drug, probably due to the enhanced uptake of SPIONs as a result of their surface modification with Glyc/PEA, demonstrating that SPION-Glyc/PEA is a good nanocarrier for co-conjugated methotrexate.

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Aim: To develop a series of superparamagnetic iron oxide nanoparticles (SPIONs) by coconjugating them with ibuprofen (ibu) and glycerol phosphate (glycerol) or ibu and glucose-1-phosphate and to assess capacity of these conjugates to inhibit the release of nitric oxide (NO) in macrophages, even at low concentrations. Materials & methods: The SPION conjugates were characterized and their properties evaluated showing the influence of those ligands on colloidal stability and inhibition of NO-release demonstrated. The cytotoxicity and possible anti-inflammatory activity were evaluated using murine macrophages (RAW 247.6). Results: SPION-glycerol phosphate/ibu conjugates inhibited the NO production induced by lipopolysaccharides, indicating a potential anti-inflammatory activity. Conclusion: SPION conjugated with ibu was shown to inhibit NO-release even at very low concentrations, suggesting possible action against inflammatory diseases.

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The effect of the ligand shell on the cellular uptake efficiency was evaluated by a systematic study using fully dispersed 6 nm diameter superparamagnetic iron oxide nanoparticles (SPIONs), mono and bis-conjugated with glycerol phosphate (glyc), dopamine (dopa), 4,5-dihydroxy-1,3-benzenedisulfonic acid (tiron) and phosphorylethanolamine (pea). Negatively charged SPION-glyc was more efficiently incorporated than positively charged SPION-pea and SPION-dopa clearly evidencing that there are strong enough short-range interactions in addition to the long-range electrostatic interactions, as measured by the zeta potential, to reverse our expectation on cellular uptake. Those effects were pursued by correlating the nanoparticles incorporation efficiency as a function of the respective zeta potentials and the molar fractions of glyc and pea ligands co-conjugated on the SPION surface. The possibility of associating different ligands to modulate the physicochemical properties and biological events was demonstrated, showing promising perspectives for the development of multifunctional nanosystems for biomedical applications.

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OBJECTIVES: To evaluate the antibacterial effects, cytotoxicity and microtensile bond strength of an adhesive containing low concentrations of silver nanoparticles (NAg). METHODS: Various concentrations of NAg (50, 100, 150, 200 and 250 ppm) were incorporated into the primer of the Scotchbond Multi-Purpose adhesive system (SBMP). Antibacterial activity was examined using a broth microdilution assay to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), agar diffusion assay and the MTT assay was used to examine the biofilm metabolic activity (S. mutans). The Microtensile Bond Test (µTBS) was performed after 24 h, followed by 6-months storage in distilled water. Cytotoxicity was assessed with an MTT reduction assay in human dental pulp stem cells viability after exposure to Nag-conditioned culture media during 0, 24, 48, and 72 h. The results were statistically analyzed (α ≤ 0.05). RESULTS: MIC was found between NAg 25 and 50 ppm MBC was determined at 50 ppm of NAg. Bacterial activity inhibition was higher than control in all NAg groups compared to control in agar diffusion assay. Biofilm inhibition was statistically higher in 250 ppm NAg than control. All NAg groups and SBMP presented similar cytotoxicity in each period. Adhesives with NAg 200 and 250 ppm and SBMP (control) presented the highest µTBS values, similar to that of SBMP control, in both instances (24 h and 6 months) (p > 0.05). CONCLUSIONS: The commercial primer containing NAg 250 ppm showed both antibacterial effect and reliable bond strength with no cytotoxicity increase. The addition of NAg to primers seems promising for the improvement of conventional dental adhesives efficacy. CLINICAL SIGNIFICANCE: The addition of low concentrations of NAg (250 ppm) to primers were effective to improve antibacterial effect preserving the bond strength and the biocompatibility of the commercial product. NAg/primer association could protect the tooth-adhesive interface increasing dental restoration longevity.

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Size, shape, and surface properties of superparamagnetic iron oxide nanoparticles (SPIONs) can influence their interaction with biological systems, particularly the incorporation by tumor cells and consequently the biological activity and efficiency in biomedical applications. Several strategies have been used to evaluate cellular uptake of SPIONs. While qualitative methods are generally based on microscopy techniques, quantitative assays are carried out by techniques such as inductively coupled plasma-mass spectrometry and flow cytometry. However, inexpensive colorimetric methods based on equipments commonly found in chemistry and biochemistry laboratories are preferred for routine measurements. Nevertheless, colorimetric assays must be used judiciously, particularly when nanoparticles are involved, since their interaction with biological constituents tends to lead to quite underestimated results. Thus, herein described is a colorimetric protocol using 2,2'-bipyridine as chromogenic ligand, where each step was optimized and validated by total reflection X-ray fluorescence spectroscopy, realizing a highly reproducible and reliable method for determination of iron content in cells incubated with SPIONs. The limit of blank and limit of detection were determined to be as low as 0.076 and 0.143 µg Fe/mL, using sample volumes as small as 190 µL and a number of cells as low as 2.0 × 105. Furthermore, three different types of surface-functionalized nanoparticles were incorporated in cells and evaluated through this protocol, enabling to monitor the additive effect of o-phosphorylethanolamine (PEA) and folic acid (FA) conjugation on iron oxide nanoparticles (SPION-PEA and SPION-PEA/FA), that enhanced the uptake by HeLa cells, respectively, by four and ten times when compared to SPIONs conjugated with nonbioactive molecules. Graphical abstract Colorimetric determination of superparamagnetic iron oxide nanoparticles (SPIONs) incorporated by cells.

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Surface enhanced Raman spectroelectrochemistry (SERS) spectroelectrochemistry provides a very sensitive technique to investigate the vibrational characteristics of coordination compounds and their particular behavior under the influence of plasmonic surfaces, concomitant with the exploitation of their redox properties and electronic spectra. The results, however, depend upon the mechanisms involved in the intensification of Raman spectra associated with the electromagnetic, resonance Raman and charge-transfer excitation at the Fermi levels. By probing the model complex [(Ru3O)(CH3COO)6(4,4'-bipy)3](n) (n = 1, 0, -1) adsorbed onto rough gold electrode surfaces, contrasting SERS profiles were obtained at several successive redox potentials and oxidation states, which enables a critical discussion on the role of the complex interaction with the gold surface, and the influence of the specific electronic bands in the triruthenium acetate cluster. Density functional theory (DFT) and time-dependent DFT calculations were carried out for the complex bound to an Au20 cluster to show the participation of active lowest unoccupied molecular orbital levels centered on the gold atoms. The corresponding charge-transfer band was predicted around 1200 nm, which supports a charge-transfer interpretation for the SERS response observed at λexc = 1064 nm. The selective enhancement of the vibrational modes was discussed based on the Raman theoretical calculations.

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The photochemical cis-trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2':6',2''-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(II) ions, and forming the [Fe(vpytpy)(2)](2+) complex. The strategy of "freezing" the cis-trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis-cis, cis-trans and trans-trans iron(II) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis-cis and cis-trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation.

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The presence of anatase and rutile domains on nanocrystalline films of P25 TiO2, as well as the distinct coordination modes of carboxylates on those phases, were revealed by confocal Raman microscopy, a technique that showed to be suitable for imaging the chemical morphology down to submicrometric size.

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Tetrapyridylporphyrins containing four chloro(2,2'-bipyridine)platinum(II) complexes attached at the meta (3-H(2)TPtPyP) and para (4-H(2)TPtPyP) positions of the peripheral pyridine ligands were synthesized and their interaction with DNA investigated. The compounds were isolated in the solid state and characterized by means of spectroscopic and analytical techniques. According to molecular simulations, the two isomers exhibit contrasting structural characteristics, consistent with a saddle shape configuration for 3-H(2)TPtPyP and a planar geometry for 4-H(2)TPtPyP. Surface plasmon resonance studies were carried out on the interaction of the complexes with calf thymus DNA, revealing a preferential binding of 3-H(2)TPtPyP, presumably at the DNA major grooves.

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