Exploring the functionalization of Ti-6Al-4V alloy with the novel antimicrobial peptide JIChis-2 via plasma polymerization.

This study aimed to characterize the immobilization of the novel JIChis-2 peptide on the Ti-6Al-4V alloy, widely used in the biomedical sector. The antimicrobial activity of JIChis-2 was evaluated in the Gram-negative bacterium E. coli. Its immobilization occurred by inducing the formation of covalent bonds between the N-terminus of the peptides and the surface previously submitted to acrylic acid polymerization via the PECVD technique. Coated and uncoated surfaces were characterized by FTIR, AFM, SEM and EDX. Studies of global and localized corrosion were carried out, seeking to explore the effects triggered by surface treatment in an aggressive environment. Additionally, the ability of the functionalized material to prevent E. coli biofilm formation evidenced that the strategy to immobilize JIChis-2 in the Ti-6Al-4V alloy via PECVD of acrylic acid resulted in the development of a functional material with antibiofilm properties.

Gold(III) complexes with thiosemicarbazonate ligands as potential anticancer agents: Cytotoxicity and interactions with biomolecular targets.

Gold(III) complexes have been studied for the past years due to their anticancer properties and great affinity to biotargets, such as enzymes and proteins, which support their pharmacological applications. Within this scope, in this work the antiproliferative activities of two Au(III)-thiosemicarbazonate complexes, [AuClL1] (1, L1: (E,Z)-N-ethyl-N'-(3-nitroso-kN)butan-2-ylidene)carbamohydrazonothioato-k2N2,S) and [Au(Hdamp)L2]Cl (2, L2: N-(N'',N''-diethylaminothiocarbonyl)-N'(N''', N'''-dimethylcarbothioamide)benzamidineto-kN,k2S and Hdamp: 2-(N,N-dimethylaminomethyl)-phenyl-C1), and their affinities to possible biological targets were investigated. Three different tumor cell lines were used to perform the cytotoxicity assays, including one cisplatin-resistant model, and the results showed lower EC50 for 1 over 2 in every case: B16F10 (4.1 µM and 15.6 µM), A431 (4.0 µM and >50 µM) and OVCAR3 (4.2 µM and 24.5 µM). However, a lower toxicity to fibroblast 3T3 cell line was observed for 2 (30.58 µM) when compared to 1 (7.17 µM), resulting in comparable therapeutic indexes. Both complexes presented strong affinity to HSA: they distorted the secondary structure of the protein, as verified by circular dichroism, but 1 additionally presented the apparent fluorescence quenching constant (Kapp) ten times greater than 2, which was probably due to the fact of 1 being able to denature HSA. The ethidium bromide displacement assay showed that neither 1 nor 2 are strong DNA intercalators, which is in agreement with what was observed through the UV-vis titration. In both cases, the 260 nm band presented hyperchromism, which can indicate ionic interactions or DNA damage. In fact, 1 was able to damage the pGEM plasmid, similarly to cisplatin, as verified by agarose gel electrophoresis and Atomic Force Microscopy. Biophysical studies in cancer cells model membranes were also performed in order to investigate the interaction of the gold complexes to lipid bilayers and revealed that the compounds interact with the membranes by exhibiting partition coefficients of 103 order of magnitude. Overall, both complexes were found to be promising candidates for the development of a future anticancer drug against low sensitive or cisplatin resistant tumors.

New insights of Nb2O5-based coatings on the 316L SS surfaces: enhanced biological responses.

This communication aims to propose new insights of Nb2O5-based coatings on the 316L SS surface with great prospects to be used in the dentistry field as brackets. The Nb2O5 thin film was incorporated into the 316L SS by using PVD method. For this purpose, the studied system was characterized structurally and morphologically by using AFM, FTIR-IRRAS, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Biological assays were performed using human gingival fibroblast cell-line HGF-1. In agreement with FTIR and Raman results, the XPS technique indicates that Nb is present in an oxidation state assigned to Nb2O5. Furthermore, the coatings produced by PVD technique are less toxic and induces less inflammation in gingival cells (cell-line HGF-1), suggesting the strategy of use Nb2O5 thin film to cover the 316L SS promoted since its protection of the physiological environment to its biocompatibility improvement.

Effects of reprocessing on chemical and morphological properties of guide wires used in angioplasty.

OBJECTIVE: To investigate the influence of the reprocessing technique of enzymatic bath with ultrasonic cleaning and ethylene oxide sterilization on the chemical properties and morphological structure of polymeric coatings of guide wire for regular guiding catheter. METHODS: These techniques simulated the routine of guide wire reprocessing in many hemodynamic services in Brazil and other countries. Samples from three different manufacturers were verified by scanning electron microscopy and X-ray photoelectron spectroscopy. RESULTS: A single or double sterilization of the catheters with ethylene oxide was not associated with morphological or chemical changes. However, scanning electron microscopy images showed that the washing method was associated with rough morphological changes, including superficial holes and bubbles, in addition to chemical changes of external atomic layers of polymeric coating surfaces, as detected by the X-ray photoelectron spectroscopy method, which is compatible with extended chemical changes on catheter surfaces. CONCLUSION: The reprocessing of the catheters with ethylene oxide was not associated with morphological or chemical changes, and it seemed appropriate to maintain guide wire coating integrity. However, the method combining chemical cleaning with mechanical vibration resulted in rough anatomical and chemical surface deterioration, suggesting that this reprocessing method should be discouraged.

Effects of reprocessing on chemical and morphological properties of guide wires used in angioplasty / Efeitos do reprocessamento nas propriedades químicas e morfológicas de fios-guia usados em angioplastia

OBJECTIVE: To investigate the influence of the reprocessing technique of enzymatic bath with ultrasonic cleaning and ethylene oxide sterilization on the chemical properties and morphological structure of polymeric coatings of guide wire for regular guiding catheter. METHODS: These techniques simulated the routine of guide wire reprocessing in many hemodynamic services in Brazil and other countries. Samples from three different manufacturers were verified by scanning electron microscopy and X-ray photoelectron spectroscopy. RESULTS: A single or double sterilization of the catheters with ethylene oxide was not associated with morphological or chemical changes. However, scanning electron microscopy images showed that the washing method was associated with rough morphological changes, including superficial holes and bubbles, in addition to chemical changes of external atomic layers of polymeric coating surfaces, as detected by the X-ray photoelectron spectroscopy method, which is compatible with extended chemical changes on catheter surfaces. CONCLUSION: The reprocessing of the catheters with ethylene oxide was not associated with morphological or chemical changes, and it seemed appropriate to maintain guide wire coating integrity. However, the method combining chemical cleaning with mechanical vibration resulted in rough anatomical and chemical surface deterioration, suggesting that this reprocessing method should be discouraged.

OBJETIVO: Investigar a influência das técnicas de reprocessamento de banho enzimático com limpeza ultrassônica e a esterilização com óxido de etileno nas propriedades químicas e estruturas morfológicas de revestimentos poliméricos de fios-guia usados como guias em cateteres regulares. MÉTODOS: Estas técnicas simulam a rotina de processamento de fios-guia em muitos serviços de hemodinâmica do Brasil e de outros países. Amostras de três diferentes fabricantes foram verificadas por microscopia eletrônica de varredura e espectroscopia de fotoelétrons de raios-X. RESULTADOS: Uma única ou dupla esterilização dos cateteres com óxido de etileno não foi associada a mudanças químicas ou morfológicas. Contudo, imagens de microscopia eletrônica de varredura mostraram que o método de lavagem foi associado a intensas modificações morfológicas, incluindo bolhas e buracos superficiais, assim como mudanças nas ligações químicas das camadas atômicas externas do revestimento polimérico, conforme demonstrado por resultados de espectroscopia de fotoelétrons de raios-X, compatível com extensas modificações químicas induzidas por esse processo de lavagem. CONCLUSÃO: O reprocessamento dos fios-guia de cateteres com óxido de etileno não está associado a mudanças químicas e morfológicas dos mesmos e pode ser considerado adequado para manter a integridade destes materiais. Entretanto, o método que combina lavagem química com vibração mecânica resulta em intensas deteriorações anatômicas e químicas, sugerindo que esse método de processamento deve ser desencorajado.