The cavity perturbation method for evaluating hematocrit via dielectric properties.

The physical parameters of human blood (complex permittivity and conductivity) at microwave frequencies have been investigated to assess the hematocrit (HCT). The cavity perturbation method based on a rectangular cavity operated in TE101mode at frequency 4.212 GHz has been utilized to measure the permittivity of blood with different hematocrit % at a range of temperatures. According to the results, the dielectric constant, loss factor, and conductivity appeared to be influenced by HCT level. Though the dielectric constant is the only parameter that shows clear linear regression decreasing behavior with a correlation value around (R2= 0.93). For thirty healthy donors the dielectric constant decreases from (65.61 ± 1.4 to 44.64 ± 4.0) and from (65.3 ± 1.2 to 48.3 ± 1.88) for men and women, respectively, with increasing hematocrit percentage from 20% HCT up to 95% HCT. The temperature dependence of the dielectric constant is also examined in the temperature range 27 °C-50 °C and the results display a slight decrease in dielectric constant with elevation temperature. The temperature-dependence dielectric constant of water and blood samples were fitted to an empirical polynomial with temperature. A comparison of estimated HCT using the cavity technique based on dielectric properties shows a very good agreement with commercially standard HCT measurement methods. Finally, the cavity technique can be applied to measure the hematocrit up to high values based on the dielectric constant with high precision, simplicity, and low cost compared with traditional techniques.

Biosensor Design for the Detection of Circulating Tumor Cells Using the Quartz Crystal Resonator Technique.

A new mass-sensitive biosensing approach for detecting circulating tumor cells (CTCs) using a quartz crystal resonator (QCR) has been developed. A mathematical model was used to design a ring electrode-based QCR to eliminate the Gaussian spatial distribution of frequency response in the first harmonic mode, a characteristic of QCRs, without compromising the sensitivity of frequency response. An ink-dot method was used to validate the ring electrode fabricated based on our model. Furthermore, the ring electrode QCR was experimentally tested for its ability to capture circulating tumor cells, and the results were compared with a commercially available QCR with a keyhole electrode. An indirect method of surface immobilization technique was employed via modification of the SiO2 surface of the ring electrode using a silane, protein, and anti-EpCAM. The ring electrode successfully demonstrated eliminating the spatial nonuniformity of frequency response for three cancer cell lines, i.e., MCF-7, PANC-1, and PC-3, compared with the keyhole QCR, which showed nonuniform spatial response for the same cancer cell lines. These results are promising for developing QCR-based biosensors for the early detection of cancer cells, with the potential for point-of-care diagnosis for cancer screening.

Dendritic cell biocompatibility of ether-based urethane films.

The use of synthetic materials for biomedical applications is ever expanding. One of the major requirements for these materials is biocompatibility, which includes prevention of immune system responses. Due to the inherent complexity of their structural composition, the polyurethane (PU) family of polymers is being used in a variety of medical applications, from soft and hard tissue scaffolds to intricate coatings on implantable devices. Herein, we investigated whether two polymer materials, D3 and D7, induced an immune response, measured by their effects on a dendritic cell (DC) line, JAWS II. Using a lactate dehydrogenase cytotoxicity assay and Annexin V/PI staining, we found that the PU materials did not induce cytotoxicity in DC cells. Using confocal microscopy, we also showed that the materials did not induce activation or maturation, as compared to positive controls. This was confirmed by looking at various markers, CD80, CD86, MHC class I, and MHC class II, via flow cytometry. Overall, the results indicated that the investigated PU films are biocompatible in terms of immunotoxicology and immunogenicity and show great promise for use in regenerative medicine.

Graphene-based 2D constructs for enhanced fibroblast support.

Complex skin wounds have always been a significant health and economic problem worldwide due to their elusive and sometimes poor or non-healing conditions. If not well-treated, such wounds may lead to amputation, infections, cancer, or even death. Thus, there is a need to efficiently generate multifunctional skin grafts that address a wide range of skin conditions, including non-healing wounds, and enable the regeneration of new skin tissue. Here, we propose studying pristine graphene and two of its oxygen-functionalized derivatives-high and low-oxygen graphene films-as potential substrates for skin cell proliferation and differentiation. Using BJ cells (human foreskin-derived fibroblasts) to represent basic skin cells, we show that the changes in surface properties of pristine graphene due to oxygen functionalization do not seem to statistically impact the normal proliferation and maturation of skin cells. Our results indicate that the pristine and oxidized graphenes presented relatively low cytotoxicity to BJ fibroblasts and, in fact, support their growth and bioactivity. Therefore, these graphene films could potentially be integrated into more complex skin regenerative systems to support skin regeneration. Because graphene's surface can be relatively easily functionalized with various chemical groups, this finding presents a major opportunity for the development of various composite materials that can act as active components in regenerative applications such as skin regeneration.

Optimizing Lignosulfonic Acid-Grafted Polyaniline as a Hole-Transport Layer for Inverted CH3NH3PbI3 Perovskite Solar Cells.

A conducting polymer of lignosulfonic acid-grafted, polyaniline-doped camphorsulfonic acid (LS-PANI-CSA), created via a low-temperature solution process, has been explored as an efficient hole-transport layer (HTL) for inverted single cation-anion CH3NH3PbI3 perovskite solar cells. The performance of the solar cell was optimized in this study by tuning the morphology and work function of LS-PANI-CSA films using dimethylsulfoxide (DMSO) as a solvent in treatment. Results showed that DMSO washing enhanced the electronic properties of the LS-PANI-CSA film and increased its hydrophobicity, which is very important for perovskite growth. The perovskite active layer deposited onto the DMSO-treated LS-PANI-CSA layer had higher crystallinity with large grain sizes (>5 µm), more uniform and complete surface coverage, and very low pinhole density and PbI2 residues compared to untreated LS-PANI-CSA. These enhancements result in higher device performance and stability. Using DMSO-treated LS-PANI-CSA as an HTL at 15 nm of thickness, a maximum 10.8% power conversion efficiency was obtained in ITO/LS-PANI-CSA/MAPbI3/PCBM/BCP/Ag inverted-device configurations. This was a significant improvement compared to 5.18% for devices based on untreated LS-PANI-CSA and a slight improvement over PEDOT:PSS-based devices with 9.48%. Furthermore, the perovskite based on treated LS-PANI-CSA showed the higher stability compared to both untreated LS-PANI-CSA and PEDOT:PSS HTL-based devices.

Simultaneous Electrochemical Deposition of Cobalt Complex and Poly(pyrrole) Thin Films for Supercapacitor Electrodes.

Supercapacitors are beneficial as energy storage devices and can obtain high capacitance values greater than conventional capacitors and high power densities compared to batteries. However, in order to improve upon the overall cost, energy density, and charge-discharge rates, the electrode material of supercapacitors needs to be fine-tuned with an inexpensive, high conducting source. We prepared a Co(III) complex and polypyrrole (PPy) composite thin films (CoN4-PPy) that was electrochemically deposited on the surface of a glassy carbon working electrode. Cyclic voltammetry studies indicate the superior performance of CoN4-PPy in charge storage in acidic electrolyte compared to alkaline and organic solutions. The CoN4-PPy material generated the highest amount of specific capacitance (up to 721.9 F/g) followed by Co salt and PPy (Co-PPy) material and PPy alone. Cyclic performance studies showed the excellent electrochemical stability of the CoN4-PPy film in the acidic medium. Simply electrochemically depositing an inexpensive Co(III) complex with a high electrically conducting polymer of PPy delivered a superior electrode material for supercapacitor applications. Therefore, the results indicate that novel thin films derived from Co(III) metal complex and PPy can store a large amount of energy and maintain high stability over many cycles, revealing its excellent potential in supercapacitor devices.

Quantification of cellular associated graphene and induced surface receptor responses.

The use of graphene for biomedical and other applications involving humans is growing and shows practical promise. However, quantifying the graphitic nanomaterials that interact with cells and assessing any corresponding cellular response is extremely challenging. Here, we report an effective approach to quantify graphene interacting with single cells that utilizes combined multimodal-Raman and photoacoustic spectroscopy. This approach correlates the spectroscopic signature of graphene with the measurement of its mass using a quartz crystal microbalance resonator. Using this technique, we demonstrate single cell noninvasive quantification and multidimensional mapping of graphene with a detection limit of as low as 200 femtograms. Our investigation also revealed previously unseen graphene-induced changes in surface receptor expression in dendritic cells of the immune system. This tool integrates high-sensitivity real-time detection and monitoring of nanoscale materials inside single cells with the measurement of induced simultaneous biological cell responses, providing a powerful method to study the impact of nanomaterials on living systems and as a result, the toxicology of nanoscale materials.

High temperature, transparent, superhydrophobic Teflon AF-2400/Indium tin oxide nanocomposite thin films.

The outstanding properties of Teflon AF-2400-chemical, optical, etc-inspired us to make modifications to enhance its hydrophobicity. We prepared an AF-2400/indium tin oxide (ITO) nanocomposite by a spin coating technique at room temperature, using the AF-2400 polymer as the matrix and ITO nanoparticles as the filler. Different ITON concentrations ranging from 3 to 30 mg ml-1 were prepared to study the effect of nanoparticle loading on the films' properties and superhydrophobicity. The effect of spin speed and annealing temperature was also studied. Atomic force microscopy, x-ray photoelectron spectroscopy, and UV-vis analysis were employed to characterize the prepared films. The results indicated that the film's low surface energy and nano/micro-features made it superhydrophobic. Increasing the ITON concentration to 15 mg ml-1 improved the superhydrophobicity of the composite film by increasing the surface roughness. The coating showed superhydrophobic behavior with a static contact angle (SCA) around 152° and contact angle hysteresis less than 2°. The nanocomposite films also exhibited excellent thermal stability, sustaining temperatures as high as 240 °C without losing their superhydrophobic behavior. Three models, Wenzel, Cassie-Baxter, and Shuttleworth-Bailey, were used to predict the SCA. The results confirmed that the latter model gave the best prediction. In addition to superhydrophobicity, the AF-2400/ITON films coated on a glass substrate showed very high transparency-around 95% in the visible and infrared ranges. An effective medium theory, the Bergman representation, was used to simulate the transmittance of the AF-2400/ITON nanocomposites. The measured and simulated transmittance values were in good agreement in the visible range. Based on our results, this coating may be highly useful for many practical applications, including solar cell coatings, chemical resistance protective coatings, and more.

Polyurethane/nano-hydroxyapatite composite films as osteogenic platforms.

A wide variety of biomaterials are utilized in tissue engineering to promote cell proliferations in vitro or tissue growth in vivo. The combination of cells, extracellular matrices, and biocompatible materials may make it possible to grow functional living tissues ranging from bone to nerve cells. In bone regeneration, polymeric scaffolds can be enhanced by the addition of bioactive materials. To this end, this study designed several ratios of polyurethane (PU) and nano-hydroxyapatite (nHA) composites (PU-nHA ratios: 100/0, 90/10, 80/20, 70/30, 60/40 w/w). The physical and mechanical properties of these composites and their relative cellular compatibility in vitro were determined. The chemical composition and crystallinity of the composites were confirmed using X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analyses. Atomic force microscopy, nano-indentation, and contact angle measurements were used to evaluate surface properties. The results showed a significant increase in surface roughness and a decrease in contact angle when the nHA concentration increased above 20%, resulting in a significant increase in hydrophilicity. These surface property changes influenced cellular behavior when MC 3T3-E1 cells were seeded on the composites. All composites were cytocompatible. There was a linear increase in cell proliferation on the 80/20 and 70/30 composites only, whereas subjective evaluation demonstrated noticeable clusters or nodules of cells (considered hallmarks of osteogenic differentiation) in the absence of any osteogenic inducers only on the 90/10 and 80/20 composites. Cellular data suggests that the 80/20 composite was an optimal environment for cell adhesion, proliferation, and, potentially, osteogenic differentiation in vitro.

Modifying Dendritic Cell Activation with Plasmonic Nano Vectors.

Dendritic cells (DCs) can acquire, process, and present antigens to T-cells to induce an immune response. For this reason, targeting cancer antigens to DCs in order to cause an immune response against cancer is an emerging area of nanomedicine that has the potential to redefine the way certain cancers are treated. The use of plasmonically active silver-coated gold nanorods (henceforth referred to as plasmonic nano vectors (PNVs)) as potential carriers for DC tumor vaccines has not been presented before. Effective carriers must be able to be phagocytized by DCs, present low toxicity, and induce the maturation of DCs-an early indication of an immune response. When we treated DCs with the PNVs, we found that the cell viability of DCs was unaffected, up to 200 µg/ml. Additionally, the PNVs associated with the DCs as they were phagocytized and they were found to reside within intracellular compartments such as endosomes. More importantly, the PNVs were able to induce expression of surface markers indicative of DC activation and maturation, i.e. CD40, CD86, and MHC class II. These results provide the first evidence that PNVs are promising carriers for DC-based vaccines and warrant further investigating for clinical use.

Triple-negative breast cancer targeting and killing by EpCAM-directed, plasmonically active nanodrug systems.

An ongoing need for new cancer therapeutics exists, especially ones that specifically home and target triple-negative breast cancer. Because triple-negative breast cancer express low or are devoid of estrogen, progesterone, or Her2/Neu receptors, another target must be used for advanced drug delivery strategies. Here, we engineered a nanodrug delivery system consisting of silver-coated gold nanorods (AuNR/Ag) targeting epithelial cell adhesion/activating molecule (EpCAM) and loaded with doxorubicin. This nanodrug system, AuNR/Ag/Dox-EpCAM, was found to specifically target EpCAM-expressing tumors compared to low EpCAM-expressing tumors. Namely, the nanodrug had an effective dose (ED50) of 3 µM in inhibiting 4T1 cell viability and an ED50 of 110 µM for MDA-MD-231 cells. Flow cytometry data indicated that 4T1 cells, on average, express two orders of magnitude more EpCAM than MDA-MD-231 cells, which correlates with our ED50 findings. Moreover, due to the silver coating, the AuNR/Ag can be detected simultaneously by surface-enhanced Raman spectroscopy and photoacoustic microscopy. Analysis by these imaging detection techniques as well as by inductively coupled plasma mass spectrometry showed that the targeted nanodrug system was taken up by EpCAM-expressing cells and tumors at significantly higher rates than untargeted nanoparticles (p < 0.05). Thus, this approach establishes a plasmonically active nanodrug theranostic for triple-negative breast cancer and, potentially, a delivery platform with improved multimodal imaging capability for other clinically relevant chemotherapeutics with dose-limiting toxicities, such as platinum-based or taxane-based therapies.

Calcium-channel blocking and nanoparticles-based drug delivery for treatment of drug-resistant human cancers.

BACKGROUND: Cancer cell chemoresistance is one of the major limitations to successful cancer treatment and one of the factors that is responsible for the possible recurrence of the disease. Here, we aimed to combine a calcium-channel blocker, verapamil, with an alternative delivery of the anti-cancer drug, doxorubicin, using nanostructural materials. This approach could reduce the cellular resistance to chemotherapeutics agents. RESULTS: The outcome of this complex approach on cellular viability was investigated by using various assays in both a time- and concentration-dependent manner: WST-1, flow cytometry cell viability assay, fluorescence microscopy, DNA fragmentation, and TUNEL labeling of apoptotic cells. CONCLUSION: All of these analytical assays confirmed the ability to reduce the chemoresistance of the cancer cells based on the proposed procedure.

Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites.

In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr) sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au) and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular) and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current was determined to be well-defined, even at relatively low concentration (10(-5) M), for the Au/Gr-AuAg-1.5 electrode. In contrast, the signals recorded with the Au/Gr-AuAg-1 electrode were poorly defined within a 5×10(-6) to 5×10(-3) M concentration range, and many of them overlapped with the background. Such composite materials could find significant applications in nanotechnology, sensing, or nanomedicine.

A novel tungsten trioxide (WO3)/ITO porous nanocomposite for enhanced photo-catalytic water splitting.

Hybrid nanocomposite films of ITO-coated, self-assembled porous nanostructures of tungsten trioxide (WO(3)) were fabricated using electrochemical anodization and sputtering. The morphology and chemical nature of the porous nanostructures were studied by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The photoelectrochemical (PEC) properties of WO(3) porous nanostructures were studied in various alkaline electrolytes and compared with those of titania nanotubes. A new type of alkaline electrolyte containing a mixture of NaOH and KOH was proposed for the first time to the best of our knowledge and shown to improve the photocurrent response of the photoanodes. Here, we show that both the WO(3) nanostructures and titania nanotubes (used for comparison) exhibit superior photocurrent response in the mixture of NaOH and KOH than in other alkaline electrolytes. The WO(3) porous nanostructures suffered from surface corrosion resulting in a huge reduction in the photocurrent density as a function of time in the alkaline electrolytes. However, with a protective coating of ITO (100 nm), the surface corrosion of WO(3) porous nanostructures reduced drastically. A tremendous increase in the photocurrent density of as much as 340% was observed after the ITO was applied to the WO(3) porous nanostructures. The results suggest that the hybrid ITO/WO(3) nanocomposites could be potentially coupled with titania nanotubes in a multi-junction PEC cell to expand the light absorption capability in the solar spectrum for water splitting to generate hydrogen.

Controlled growth of self-organized hexagonal arrays of metallic nanorods using template-assisted glancing angle deposition for superhydrophobic applications.

The fabrication of controlled, self-organized, highly ordered tungsten and aluminum nanorods was accomplished via the aluminum lattice template-assisted glancing angle sputtering technique. The typical growth mechanism of traditional glancing angle deposition technique was biased by self-organized aluminum lattice seeds resulting in superior quality nanorods in terms of size control, distribution, and long range order. The morphology, size, and distribution of the nanorods were highly controlled by the characteristics of the template seeds indicating the ability to obtain metallic nanorods with tunable distributions and morphologies that can be grown to suit a particular application. Water wettability of hexagonally arranged tungsten and aluminum nanorods was studied after modifying their surface with 5 nm of Teflon AF 2400, as an example, to exhibit the significance of such a controlled growth of metallic nanorods. This facile and scalable approach to generate nano seeds to guide GLAD, with nano seeds fabricated by anodic oxidization of aluminum followed by chemical etching, for the growth of highly ordered nanorods could have significant impact in a wide range of applications such as anti-icing coating, sensors, super capacitors, and solar cells.

Design and fabrication of teflon-coated tungsten nanorods for tunable hydrophobicity.

The nature of water interaction with tungsten nanorods (WNRs) fabricated by the glancing-angle deposition technique (GLAD)-using RF magnetron sputtering under various Ar pressures and substrate tilting angles and then subsequent coating with Teflon-has been studied and reported. Such nanostructured surfaces have shown strong water repellency properties with apparent water contact angles (AWCA) of as high as 160°, which were found to depend strongly upon the fabrication conditions. Variations in Ar pressure and the substrate tilting angle resulted in the generation of WNRs with different surface roughness and porosity properties. A theoretical model has been proposed to predict the observed high AWCAs measured at the nanostructure interfaces. The unique pyramidal tip geometry of WNRs generated at low Ar pressure with a high oblique angle reduced the solid fraction at the water interface, explaining the high AWCA measured on such surfaces. It was also found that the top geometrical morphologies controlling the total solid fraction of the WNRs are dependent upon and controlled by both the Ar pressure and substrate tilting angle. The water repellency of the tungsten nanorods with contact angles as high as 160° suggests that these coatings have enormous potential for robust superhydrophobic and anti-icing applications in harsh environments.