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Background/aims Silver nanoparticles (AgNPs) are the most frequently used nanomaterials in industrial and biomedical applications. Their functionalization significantly impacts their properties and potential applications. Despite the need to produce, investigate and apply them, not much is known about the toxicity of silver nanoparticles to and their interaction with blood components, such as erythrocytes. Here, we report on the effect of two negatively charged AgNPs (Creighton, and Lee-Meisel) on ion transport in human red blood cells (HRBCs). Methods HRBCs were obtained from blood of adult donors, which was either expired, fresh or refrigerated for variable lengths of time, and from fresh or refrigerated cord blood. Rb+ and K+ ions were measured by atomic emission and absorption spectrophotometry, respectively. Erythrocyte hemoglobin optical density (Hbc OD), was determined at 527 nm to estimate RBC volume in the same tubes in which Rb+ and K+ were measured. Cellular Rb+ uptake and intracellular K+ concentrations, [K]i, were calculated in mmol/L of original cells (LOC) per time. Rubidium, a potassium ion (K+) congener used to measure K+ influx, [K]i, and Hbc ODs were determined in the presence and absence of several concentrations (0-150 µg mL-1) of spherical AgNPs of an average diameter of 10 nm, at different time points (0-60 min). Results Creighton AgNPs inhibited Rb+ influx and depleted the cells of K+ independently of the source and in a time and dose-dependent manner. In contrast, Lee-Meisel AgNPs caused ~ 50 % Rb+ influx inhibition and ~ 15 % K+ loss with larger interindividual variability than Creighton AgNPs. The loss of K+ from HRBCs was entirely accounted for by an increase in extracellular K+ concentration, [K]o. Enhanced dark field optical microscopy in conjunction with CytoViva® hyperspectral imaging helped visualize AgNPs internalized by HRBCs, thus pointing to a potential cause for their cytotoxic effects. Conclusion These findings indicate that HRBC K+ homeostasis is an early and sensitive biomarker for AgNPs toxicity and is a function of their surface functionalization.

Betulinic acid (BA), a natural compound with various health benefits including selective antitumor activity, has a limited applicability in vivo due to its poor water solubility and bioavailability. Thus, this study focused on obtaining a BA nano-sized formulation with improved solubility and enhanced antitumor activity using silver nanocolloids (SilCo and PEG_SilCo) as drug carriers. The synthesis was performed using a chemical method and the physicochemical characterization was achieved applying UV-Vis absorption, transmission electron microscopy (TEM), Raman and photon correlation spectroscopy (PCS). The biological evaluation was conducted on two in vitro experimental models&mdash, hepatocellular carcinoma (HepG2) and lung cancer (A549) cell lines. The physicochemical characterization showed the following results: an average hydrodynamic diameter of 32 nm for SilCo_BA and 71 nm for PEG_SilCo_BA, a spherical shape, and a loading capacity of 54.1% for SilCo_BA and 61.9% for PEG_SilCo_BA, respectively. The in vitro assessment revealed a cell type- and time-dependent cytotoxic effect characterized by a decrease in cell viability as follows: (i) SilCo_BA (66.44%) &lt, PEG_SilCo_BA (72.05%) &lt, BA_DMSO (75.30%) in HepG2 cells, and (ii) SilCo_BA (75.28%) &lt, PEG_SilCo_BA (86.80%) &lt, BA_DMSO (87.99%) in A549 cells. The novel silver nanocolloids loaded with BA induced an augmented anticancer effect as compared to BA alone.

A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by estimating the analytical enhancement factor (AEF) and surface enhancement factor (SEF) of the AgNPs, that is, the most important values for characterizing the SERS effect. SERS is an embodiment of Raman spectroscopy that currently finds numerous cutting-edge applications. To achieve this, students synthesized a Creighton colloid and characterized its optical properties by UV–vis absorption spectrophotometry. The AEF and SEF values were then estimated from the measured Raman, SERS, and fluorescence emission spectra of a test probe, rhodamine 6G, adsorbed on the colloidal AgNPs. This laboratory experiment introduced the students to the fundamentals of SERS spectroscopy an...