RESUMEN
The work is focused on the degradation, cytotoxicity, and antibacterial properties, of iron-based biomaterials with a bioactive coating layer. The foam and the compact iron samples were coated with a polyethylene glycol (PEG) polymer layer without and with gentamicin sulfate (PEG + Ge). The corrosion properties of coated and uncoated samples were studied using the degradation testing in Hanks' solution at 37 °C. The electrochemical and static immersion corrosion tests revealed that the PEG-coated samples corroded faster than samples with the bioactive PEG + Ge coating and uncoated samples. The foam samples corroded faster compared with the compact samples. To determine the cytotoxicity, cell viability was monitored in the presence of porous foam and compact iron samples. The antibacterial activity of the samples with PEG and PEG + Ge against Escherichia coli CCM 3954 and Staphylococcus aureus CCM 4223 strains was also tested. Tested PEG + Ge samples showed significant antibacterial activity against both bacterial strains. Therefore, the biodegradable iron-based materials with a bioactive coating could be a suitable successor to the metal materials studied thus far as well as the materials used in the field of medicine.
RESUMEN
Coating of the biodegradable metals represents an effective way of modification of their properties. Insufficient biological, mechanical, or degradation performance of pure metals may be enhanced when the proper type of organic polymer coating is used. In our previous work, the significant effect of the polyethyleneimine (PEI) coating not only on the rate but also on the type of corrosion was discovered. To bring a comprehensive overview of the Fe-PEI system performance, iron-based biodegradable scaffolds with polyethyleneimine coating were studied and their cytocompatibility and hemocompatibility, and mechanical properties were evaluated and discussed in this work. Electrochemical impedance spectroscopy (EIS) measurements were conducted for further study of material behavior. Biological analyses (MTS assay, fluorescent imaging, hemocompatibility tests) showed better cell proliferation on the surface of Fe-PEI samples but not sufficient overall cytocompatibility. Good anti-platelet adhesion properties but higher hemolysis when compared to the pure iron was also observed for the coated samples. Mechanical properties of the prepared Fe-PEI material were enhanced after coating. These findings suggest that the Fe-PEI may be an interesting potential biomaterial after further composition optimization resulting in lower cytotoxicity and better hemocompatibility.
Asunto(s)
Hierro , Polietileneimina , Aleaciones/química , Materiales Biocompatibles/química , Materiales Biocompatibles/farmacología , Corrosión , Hierro/química , Hierro/farmacología , Ensayo de Materiales , Polietileneimina/farmacologíaRESUMEN
This work presents the NiAg nanocavity film for the detection of organic dyes by surface-enhanced Raman spectroscopy (SERS). Nanocavity films were prepared by colloidal lithography using 518-nm polystyrene spheres combined with the electrochemical deposition of Ni supporting layer and Ag nanoparticles homogeneous SERS-active layer. The theoretical study was modelled by finite-difference time-domain (FDTD) simulation of electromagnetic field enhancement near the nanostructured surface and experimentally proven by SERS measurement of selected organic dyes (rhodamine 6G, crystal violet, methylene blue, and malachite green oxalate) in micromolar concentration. Furthermore, the concentration dependence was investigated to prove the suitability of NiAg nanocavity films to detect ultra-low concentrations of samples. The detection limit was 1.3 × 10-12, 1.5 × 10-10, 1.4 × 10-10, 7.5 × 10-11 mol·dm-3, and the standard deviation was 20.1%, 13.8%, 16.7%, and 19.3% for R6G, CV, MB, and MGO, respectively. The analytical enhancement factor was 3.4 × 105 using R6G as a probe molecule. The principal component analysis (PCA) was performed to extract the differences in complex spectra of the dyes where the first and second PCs carry 42.43% and 31.39% of the sample variation, respectively. The achieved results demonstrated the suitability of AgNi nanocavity films for the SERS-based detection of organic dyes, with a potential in other sensing applications.
RESUMEN
Surface-enhanced Raman spectroscopy (SERS) of blood plasma on an electrochemically prepared silver surface has been studied as a label-free, noninvasive diagnostic test for colorectal cancer. Indium tin oxide glass substrates were modified with 0.01 mol dm - 3 silver nitrate using the pulsed double-potentiostatic method. The prepared silver substrates were tested with Rhodamine 6G as a model analyte and the surface with the highest signal enhancement was selected. This silver dendritic surface was used as a diagnostic substrate for SERS measurements of human blood plasma. A group of oncological patients with declared colorectal carcinoma (n = 15) and the control group of healthy volunteers (n = 15) were compared. The biomolecular changes in chemical composition in the cancer samples were detected by statistical processing of the resulting SERS spectra. About 94% specificity and 100% sensitivity were achieved for the analysis by the ratio of the SERS peak intensity at 725 cm - 1 for adenine to the peak intensity at 638 cm - 1 for tyrosine and 100% specificity and sensitivity by using principal component analysis. This method of SERS diagnostics of colorectal cancer, which does not require the nanoparticle preparation, mixing, and incubation of plasma with a colloidal solution as in conventional tests, is a rapid, inexpensive method, which could be introduced as a primary diagnostic test.
Asunto(s)
Neoplasias Colorrectales/diagnóstico , Nanopartículas del Metal/química , Plata/química , Espectrometría Raman/métodos , Biomarcadores de Tumor/sangre , Neoplasias Colorrectales/sangre , Técnicas Electroquímicas , Humanos , Análisis de Componente Principal , Sensibilidad y Especificidad , Procesamiento de Señales Asistido por ComputadorRESUMEN
Biodegradable metallic implants are of significant importance in the replacement of bones or the repair of bone defects. Iron-phosphate-coated carbonyl iron powder (Fe/P) was prepared by the phosphating method. Moreover, Fe/P-Mn alloy was produced by sintering the Fe/P powder mixed with manganese powder. Bare carbonyl iron samples and the Fe/P and Fe/P-Mn sintered samples were evaluated for their microstructure, cytotoxicity, and hemocompatibility. The microstructure of the sintered samples was examined using an optical microscope and scanning electron microscopic analysis. Corrosion behavior was evaluated by potentiodynamic polarization in Hank's solution. The in vitro biocompatibilities were investigated by cytotoxicity and hemolysis tests. The results obtained demonstrate that the addition of Mn resulted in higher surface inhomogeneity, porosity and roughness as well as in increased cytotoxicity. The phosphate coating has a moderately negative effect on the cytotoxicity. The corrosion rates determined from Tafel diagrams were ordered in the following sequence: Fe/P-Mn, Fe, Fe/P from high to low. The hemocompatibility of experimental samples was ordered in the following sequence: Fe/P, Fe/P-Mn, Fe from high to low. All samples were found to be hemocompatible.