silicon and Influenza--Human

The surface protein hemagglutinin (HA) mediates the attachment of influenza virus to host cells containing sialic acid and thus facilitates viral infection. Therefore, HA is considered as a good target for the development of diagnostic tools for influenza virus. Previously, we reported the isolation of single-stranded aptamers that can distinguish influenza subtype H1 from H5. In this study, we describe a method for the selective electrical detection of H1 using the isolated aptamer as a molecular probe. After immobilization of the aptamer on Si wafer, enzyme-linked immunosorbent assay (ELISA) and field emission scanning electron microscopy (FE-SEM) showed that the immobilized aptamer bound specifically to the H1 subtype but not to the H5 subtype. Assessment by cyclic voltammetry (CV) also demonstrated that the immobilized aptamer on the indium thin oxide-coated surface was specifically bound to the H1 subtype only, which was consistent with the ELISA and FE-SEM results. Further measurement of CV using various amounts of H1 subtype provided the detection limit of the immobilized aptamer, which showed that a nanomolar scale of target protein was sufficient to produce the signal. These results indicated that the selected aptamer can be an effective probe for distinguishing the subtypes of influenza viruses by monitoring current changes.

Topics: Aptamers, Nucleotide; DNA, Single-Stranded; Enzyme-Linked Immunosorbent Assay; Hemagglutinin Glycoproteins, Influenza Virus; Humans; Immobilization; Influenza, Human; Microscopy, Electron, Scanning; Molecular Probe Techniques; Molecular Probes; Orthomyxoviridae; SELEX Aptamer Technique; Silicon

A flexible diagnostic platform is realized and its performance is demonstrated for early detection of avian influenza virus (AIV) subtype H1N1 DNA sequences. The key component of the platform is high-performance biosensors based on high output currents and low power dissipation Si nanowire field effect transistors (SiNW-FETs) fabricated on flexible 100 μm thick polyimide foils. The devices on a polymeric support are about ten times lighter compared to their rigid counterparts on Si wafers and can be prepared on large areas. While the latter potentially allows reducing the fabrication costs per device, the former makes them cost efficient for high-volume delivery to medical institutions in, e.g., developing countries. The flexible devices withstand bending down to a 7.5 mm radius and do not degrade in performance even after 1000 consecutive bending cycles. In addition to these remarkable mechanical properties, on the analytic side, the diagnostic platform allows fast detection of specific DNA sequences of AIV subtype H1N1 with a limit of detection of 40 × 10(-12) m within 30 min suggesting its suitability for early stage disease diagnosis.

Topics: Biosensing Techniques; DNA, Viral; Humans; Influenza A Virus, H1N1 Subtype; Influenza, Human; Nanowires; Silicon; Transistors, Electronic

Influenza A viruses (IAVs) cause recurrent epidemics in humans, with serious threat of lethal worldwide pandemics. The occurrence of antiviral-resistant virus strains and the emergence of highly pathogenic influenza viruses have triggered an urgent need to develop new anti-IAV treatments. One compound found to inhibit IAV, and other virus infections, is saliphenylhalamide (SaliPhe). SaliPhe targets host vacuolar-ATPase and inhibits acidification of endosomes, a process needed for productive virus infection. The major obstacle for the further development of SaliPhe as antiviral drug has been its poor solubility. Here, we investigated the possibility to increase SaliPhe solubility by loading the compound in thermally hydrocarbonized porous silicon (THCPSi) nanoparticles. SaliPhe-loaded nanoparticles were further investigated for the ability to inhibit influenza A infection in human retinal pigment epithelium and Madin-Darby canine kidney cells, and we show that upon release from THCPSi, SaliPhe inhibited IAV infection in vitro and reduced the amount of progeny virus in IAV-infected cells. Overall, the PSi-based nanosystem exhibited increased dissolution of the investigated anti-IAV drug SaliPhe and displayed excellent in vitro stability, low cytotoxicity, and remarkable reduction of viral load in the absence of organic solvents. This proof-of-principle study indicates that PSi nanoparticles could be used for efficient delivery of antivirals to infected cells.

Topics: Amides; Animals; Dogs; Drug Carriers; Drug Delivery Systems; Humans; Influenza A virus; Influenza, Human; Madin Darby Canine Kidney Cells; Microscopy, Fluorescence; Models, Chemical; Nanoparticles; Nanotechnology; Particle Size; Salicylates; Silicon; Solvents

Influenza epidemics worldwide result in substantial economic and human costs annually. However, rapid and reliable flu diagnosis methods are significantly lacking. Here we have demonstrated the selective detection of influenza A viruses down to 29 viruses/μL in clinical exhaled breath condensate (EBC) samples (diluted by 100-fold) within minutes using silicon nanowire (SiNW) sensor devices. For 90% of the cases, we have observed that EBC samples tested positive or negative by gold standard method RT-qPCR generated corresponding positive or negative SiNW sensor responses. High selectivity of SiNW sensing was also demonstrated using H1N1 viruses, 8 iso PGF 2a, and inert nanoparticles. Finally, magnetic beads were shown capable of enhancing SiNW sensing directly for low level viruses and 8 iso PGF 2a. When calibrated by virus standards and EBC controls, our work suggests that the SiNW sensor device can be reliably applied to the diagnosis of flu in a clinical setting with 2 orders of magnitude less time compared to the gold standard method RT-qPCR.

Topics: Biosensing Techniques; Breath Tests; Humans; Immunoassay; Influenza A Virus, H3N2 Subtype; Influenza, Human; Nanowires; Particle Size; Reverse Transcriptase Polymerase Chain Reaction; Silicon; Surface Properties

Metal dust exposure strongly affects human health, especially for smelters. Little is known, however, about the impact of metal dust exposure on influenza-associated lung function decrement risk in smelters. Different body mass index (BMI) groups were also associated with respiratory diseases. The purpose of this study was to use a probabilistic risk assessment approach to explicitly link occupational metal dust exposure, BMI-correlated health effects, and influenza-associated lung function decrements to investigate potential risk among smelters. Here we showed that (i) influenza A-associated metal dust exposure in SiMn/FeMn/FeCr smelters had slightly higher health risks than that in FeSi/Si-metal's, (ii) BMI≥35 had the highest risk in respiratory infection exacerbations, and (iii) the estimated smelting metal dust induced forced expiratory volume in 1s (FEV(1)) decreasing rates were 0.59 and 1.11 m(3) mg(-1) for FeSi/Si-metal and SiMn/FeMn/FeCr smelters, respectively. Our results suggested that smelters better be aware of severe weight gains (e.g., BMIs from 27-40) because it is likely to lead to 17-25% decrements in lung function. This study provides a novel probabilistic risk assessment framework to quantitatively assess the occupational health risk posed by metal dust exposure associated with influenza infection based on BMI measures.

Topics: Adult; Air Pollutants, Occupational; Body Mass Index; Dust; Female; Forced Expiratory Volume; Humans; Influenza, Human; Lung; Male; Metallurgy; Metals, Heavy; Occupational Exposure; Risk Assessment; Silicon; Young Adult

An integrated microfluidic device capable of performing a variety of genetic assays has been developed as a step towards building systems for widespread dissemination. The device integrates fluidic and thermal components such as heaters, temperature sensors, and addressable valves to control two nanoliter reactors in series followed by an electrophoretic separation. This combination of components is suitable for a variety of genetic analyses. As an example, we have successfully identified sequence-specific hemagglutinin A subtype for the A/LA/1/87 strain of influenza virus. The device uses a compact design and mass production technologies, making it an attractive platform for a variety of widely disseminated applications.

Topics: Animals; DNA Primers; DNA, Viral; Electrophoresis; Glass; Hemagglutinin Glycoproteins, Influenza Virus; Hot Temperature; Humans; Image Processing, Computer-Assisted; Influenza, Human; Mice; Microfluidic Analytical Techniques; Microfluidics; Miniaturization; Oligonucleotide Array Sequence Analysis; Plasmids; Polymerase Chain Reaction; Sequence Analysis, DNA; Silicon; Temperature; Time Factors