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Although antimicrobial nanosilver finds numerous applications in the health and food industries, the in vivo toxicity of positively charged silver nanoparticles (AgNPs

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.

Purpose Surface-enhanced Raman scattering (SERS) spectroscopy on serum and other biofluids for cancer diagnosis represents an emerging field, which has shown promising preliminary results in several types of malignancies. The purpose of this study was to demonstrate that SERS spectroscopy on serum can be employed for the differential diagnosis between five of the leading malignancies, ie, breast, colorectal, lung, ovarian and oral cancer. Patients and methods Serum samples were acquired from healthy volunteers (n=39) and from patients diagnosed with breast (n=42), colorectal (n=109), lung (n=33), oral (n=17), and ovarian cancer (n=13), comprising n=253 samples in total. SERS spectra were acquired using a 532 nm laser line as excitation source, while the SERS substrates were represented by Ag nanoparticles synthesized by reduction with hydroxylamine. The classification accuracy yielded by SERS was assessed by principal component analysis-linear discriminant analysis (PCA-LDA). Results The sensitivity and specificity in discriminating between cancer patients and controls was 98% and 91%, respectively. Cancer samples were correctly assigned to their corresponding cancer types with an accuracy of 88% for oral cancer, 86% for colorectal cancer, 80% for ovarian cancer, 76% for breast cancer and 59% for lung cancer. Conclusion SERS on serum represents a promising strategy of diagnosing cancer which can discriminate between cancer patients and controls, as well as between cancer types such as breast, colorectal, lung ovarian and oral cancer.

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.

Silver nanoparticles (AgNPs) are widely used in a variety of industrial and consumer applications and the disposal AgNP-containing materials is a potential source of environmental contamination. This study investigated the reaction of AgNPs with synthetic birnessite (δ-MnO2), a naturally-occurring MnO2 soil mineral shown in previous studies to oxidize both organic and inorganic dissolved species. The AgNPs used in this study ranged in size from 5 to 25 nm with an average particle diameter of 15.6 nm. Batch and kinetic reactions of MnO2-treated AgNP suspensions were studied by detecting AgNP oxidation to Ag+ using a combination of UV-Vis and microwave plasma atomic emission (MP-AES) spectrometries. Synchrotron K-edge X-ray absorption spectroscopy (XANES and EXAFS) was used to investigate the Ag oxidation state and structural characteristics of the reaction products. Oxidation of AgNP by MnO2 was detected in batch reactions showing an initial fast oxidation of AgNP to Ag+ (0–10 min) followed by a slower reaction (> 10 min) where Ag+ was removed by adsorption on MnO2 surfaces. XANES results confirmed that total AgNP oxidation by MnO2 occurred after 48 h when the Mn:Ag mole ratio treatment exceeded 5:1. The final AgNP oxidation product determined by EXAFS was Ag+ ion bound as a AgO4 tetrahedral structure in MnO2 interlayer cation exchange sites with Ag-O and Ag-Mn inter-atomic distances of 2.28 (± 0.02) and 3.88 (± 0.09) A, respectively. This structure is in agreement with previous EXAFS studies of naturally-occurring Ag-bearing MnO2 mineral samples and represents one of many possible Ag+ binding sites on soil mineral surfaces.

Aim: Previous studies regarding surface-enhanced Raman scattering (SERS) of serum have shown promising initial results in discriminating prostate cancer, a strategy which could complement standard tests such as the prostate-specific antigen (PSA). Materials & methods: SERS spectra of serum samples were combined with serum PSA levels to improve the discrimination accuracy between prostate cancer and nonmalignant pathologies in a cohort of 54 patients using principal component analysis-linear discriminant analysis (PCA-LDA). Results & discussion: Combining SERS spectra with serum PSA levels in a single PCA-LDA model could discriminate between the two groups with an overall accuracy of 94%, yielding better results than either method alone. Conclusion: These results highlight that combining SERS-based cancer screening with serum PSA levels represents a promising strategy for improving the accuracy of prostate cancer diagnosis.

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...