No abstract

Iron-excess Mn-Zn ferrite nanoparticles were prepared by coprecipitation with sodium hydroxide (NaOH) at different concentrations (0.1, 0.2, 0.5 and 1.0 mol/L). The results of X-ray diffraction (XRD) analysis using Whole Powder Pattern Modeling (WPPM) showed that higher concentrations of NaOH promote crystallite growth and broader dispersion in crystallite sizes. Energy dispersive X-ray spectroscopy indicates that zinc loss is noticeable when [NaOH] ≥ 0.2 mol/L. XRD revealed also a significant less-crystalline phase contribution alongside the main peaks of the nanocrystalline cubic spinel ferrite phase. The less-crystalline fraction is lower for the ferrite obtained with 0.2 mol/L of NaOH, being about 50% and more than 70% for the other samples. Despite of the less-crystalline fraction and the excess of iron, no secondary phases were detected. The Warren curves showed that the concentration of NaOH significantly influences the microstrain in the crystallites, being smaller for the sample obtained with NaOH at 0.2 mol/L. The sample prepared with this condition presented the better properties to be used as magnetic tracer in clinical diagnoses combining small mean crystallite size, low microstrain, which resulted in materials with higher magnetic saturation and high surface charge under blood pH.

A simple method for immobilization of the chemotherapy drug paclitaxel (PTX) on hydroxyapatite nanoparticles (n-HAP) using the biopolymer chitosan as a trapping agent is described focusing on applications involving breast cancer cells. n-HAP with two distinct crystallinity profiles were used: with predominant crystallization along the long axis and with a more homogeneous crystallization in all directions. In the first scenario, the interactions between chitosan and both the OH and PO 4 3− groups on the surface of the nanoparticles are favored and lead to a more efficient attachment of the drug. In this case, PTX is found to remain mostly attached to the n-HAP for at least 24 h, while being dispersed in aqueous solution. During this time, the activity of the drug is inhibited as corroborated by in vitro assays with breast cancer cells. With that, the in vitro experiments revealed distinct effects from the drug-loaded nanoparticles on the cells depending on the experimental conditions. In a short term, that is, in 24 h, the cells exhibit higher viability than those challenged with nonloaded materials. Nevertheless, after 72 h, even a small content of PTX in the presence of n-HAP can reduce the cells' viability via stimulation of the apoptotic phenotype and suppression of survival stimuli.

Here we described an aptasensor based on graphene oxide (GO) decorated with gold nanoparticles (AuNPs) able to detect the AR released by prostate cells, in order to provide new insights about the relationship between AR and prostate cancer for a more precise diagnosis for cancer. Characterization of the surface modified GE was carried out by cyclic voltammetry and electrochemical impedance spectroscopy using ferrocene as a redox probe. Under the optimized experimental conditions, a detection limit of 0.5 ng/mL (3σ/slope) was obtained by the present electrochemical biosensor, along with a linear range of 0-110 ng/mL. By virtue of excellent sensitivity, specificity, and repeatability, the present electrochemical biosensor provides a potential application in clinical diagnosis.