Browsing by Author "Martins, Marcos A. P."
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Item Dicationic Imidazolium-Based Ionic Liquids: A New Strategy for Non-Toxic and Antimicrobial Materials(Royal Soc Chemistry) Gindri, Izabelle M.; Siddiqui, Danyal A.; Bhardwaj, Pooja; Rodriguez, Lucas C.; Palmer, Kelli L.; Frizzo, Clarissa P.; Martins, Marcos A. P.; Rodrigues, Danieli C.; Palmer, Kelli L.; Rodrigues, Danieli C.New dicationic imidazolium-based ionic liquids (ILs) were synthesized, characterized and tested in regards to cytotoxicity and antimicrobial activity. Insertion of a new cationic head and use of organic anions increased the biocompatibility of the ILs developed. IC₅₀ (concentration necessary to inhibit 50% of enzymatic activity) values obtained were considerably higher than those described for monocationic ILs, which indicates an improvement in cytocompatibility. Antimicrobial activity against bacterial species of clinical relevance in wounds and the oral environment was tested. The results showed that ILs were effective in inhibiting bacterial growth even below the minimum inhibitory concentration (MIC). It was observed that structural features that confer higher hydrophobicity to ILs decreased both the IC₅₀ and MIC simultaneously. However, it was possible to establish an equilibrium between those two effects, which gives the safe range of concentrations that ILs can be employed. The results demonstrated that the dicationic-imidazolium-based ILs synthesized may constitute a potent strategy for applications requiring non-toxic materials exhibiting antimicrobial activity.Item Evaluation of Mammalian and Bacterial Cell Activity on Titanium Surface Coated with Dicationic Imidazolium-Based Ionic Liquids(Royal Soc Chemistry, 2016-04-04) Gindri, Izabelle M.; Palmer, Kelli L.; Siddiqui, Danyal A.; Aghyarian, Shant; Frizzo, Clarissa P.; Martins, Marcos A. P.; Rodrigues, Danieli C.; 0000-0002-7343-9271 (Palmer, KL); Gindri, Izabelle M.; Palmer, Kelli L.; Siddiqui, Danyal A.; Aghyarian, Shant; Rodrigues, Danieli C.This work presents a new strategy to protect titanium surfaces against bacterial colonization and biofilm formation using dicationic imidazolium-based ionic liquid coatings. Ionic liquids (ILs) were designed as multi-functional coatings and their compatibility with human gingival fibroblasts (HGF-1) and preosteoblast (MC3T3-E1) cells was investigated. Results demonstrated that IL coatings were stable and present on titanium surfaces after 7 days of immersion and showed that using phenylalanine as the anionic moiety allowed for cell proliferation and differentiation on titanium surface while also providing strong antimicrobial and anti-biofilm activity against bacterial strains relevant to the oral environment (Streptococcus sp.). Strains such as Streptococcus mutans, S. sanguinis, S salivarius, S. gordonii and S. uberis are known to colonize the surface of dental implants in the early stages after implantation (early colonizers), compromising the success of these devices. The "race for the surface" between cells and bacteria was established by correlating results obtained from cell proliferation (epithelial and osteoblast) and differentiation (osteoblast) studies with that of antimicrobial activity against early bacterial colonizers.Item Thermodynamic, Energetic, and Topological Properties of Crystal Packing of Pyrazolo[1,5-a] Pyrimidines Governed by Weak Electrostatic Intermolecular Interactions(Royal Soc Chemistry) Frizzo, Clarissa P.; Tier, Aniele Z.; Gindri, Izabelle M.; Meyer, Alexandre R.; Black, Gabrielle; Belladona, Andrei L.; Martins, Marcos A. P.; Gindri, Izabelle M.; Martins, Marcos A. P.A series of pyrazolo[1,5-a] pyrimidines was used as a molecular model in order to understand the crystal packing of compounds with weak electrostatic intermolecular interactions. Additionally, the relationship between the energetic content of intermolecular interactions, the contact surfaces of molecules, and the thermodynamic properties of the crystal was established. The approach, which is based on a supramolecular cluster, shows that for compounds with weak electrostatic intermolecular interactions, the energetic content of the interactions is associated with a large contact surface. The crystal packing of the studied compounds is mainly governed by interactions that involve high interaction energy over a large contact surface. These results show that pi center dot center dot center dot pi interaction may be as responsible as other strong interactions for driving the crystal packing of compounds with weak electrostatic intermolecular interactions. Furthermore, the correlation between sublimation enthalpy and cluster energy showed that the theoretical calculation of cluster energy provided the real energetic content of crystal lattice energy and confirmed that the first coordination sphere (the supramolecular cluster) is the smallest portion of the crystal that represents all the information necessary for understanding the intermolecular interactions over the entire crystal.