| 1. |
- Unksov, Ivan N., et al.
(författare)
-
Fluorescence excitation enhancement by waveguiding nanowires
- 2023
-
Ingår i: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 5:6, s. 1760-1766
-
Tidskriftsartikel (refereegranskat)abstract
- The optical properties of vertical semiconductor nanowires can allow an enhancement of fluorescence from surface-bound fluorophores, a feature proven useful in biosensing. One of the contributing factors to the fluorescence enhancement is thought to be the local increase of the incident excitation light intensity in the vicinity of the nanowire surface, where fluorophores are located. However, this effect has not been experimentally studied in detail to date. Here, we quantify the excitation enhancement of fluorophores bound to a semiconductor nanowire surface by combining modelling with measurements of fluorescence photobleaching rate, indicative of the excitation light intensity, using epitaxially grown GaP nanowires. We study the excitation enhancement for nanowires with a diameter of 50-250 nm and show that excitation enhancement reaches a maximum for certain diameters, depending on the excitation wavelength. Furthermore, we find that the excitation enhancement decreases rapidly within tens of nanometers from the nanowire sidewall. The results can be used to design nanowire-based optical systems with exceptional sensitivities for bioanalytical applications.
|
|
| 2. |
- Unksov, Ivan N., et al.
(författare)
-
Semiconductor nanowires for biosening
- 2023
-
Ingår i: European Biophysics Journal. - 1432-1017 .- 0175-7571. ; 52:SUPPL 1, s. S40-S40
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Semiconductor nanowires are known to enhance the signal of fluorophores in their proximity. In our recent work, we optimized GaP nanowires to maximize the enhancement of fluorescence excitation. For that, we used optical microscopy to measure the fluorescence photobleaching rate on the nanowires, proportional to local excitation. From the measurements and modelling, we show for red fluorophores (excitation wavelength 640 nm) that nanowires with diameters of 90–130 nm enable enhancement of over a factor of 5 compared to bulk solution. We also demonstrate that a 10 nm oxide layer on the nanowires enables functionalisation using biotin-streptavidin chemistry without hindering the enhancement. Such nanowires were used in our laboratory to detect fluorescently-labelled proteins on a single molecule level. Now we employ these results for detection of down to nanomolar concentrations of DNA in solution, and in our poster, we discuss these biosensors.
|
|
| 3. |
- Abariute, Laura, et al.
(författare)
-
Uptake of nanowires by human lung adenocarcinoma cells
- 2019
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:6
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires are increasingly used in optoelectronic devices. However, their effects on human health have not been assessed fully. Here, we investigate the effects of gallium phosphide nanowires on human lung adenocarcinoma cells. Four different geometries of nanowires were suspended in the cell culture for 48 hours. We show that cells internalize the nanowires and that the nanowires have no effect on cell proliferation rate, motility, viability and intracellular ROS levels. By blocking specific internalization pathways, we demonstrate that the nanowire uptake is the result of a combination of processes, requiring dynamin and actin polymerization, which suggests an internalization through macropinocytosis and phagocytosis.
|
|
| 4. |
- Berthing, Trine, et al.
(författare)
-
Pulmonary toxicity and translocation of gallium phosphide nanowires to secondary organs following pulmonary exposure in mice
- 2023
-
Ingår i: Journal of Nanobiotechnology. - 1477-3155. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: III-V semiconductor nanowires are envisioned as being integrated in optoelectronic devices in the near future. However, the perspective of mass production of these nanowires raises concern for human safety due to their asbestos- and carbon nanotube-like properties, including their high aspect ratio shape. Indeed, III-V nanowires have similar dimensions as Mitsui-7 multi-walled carbon nanotubes, which induce lung cancer by inhalation in rats. It is therefore urgent to investigate the toxicological effects following lung exposure to III-V nanowires prior to their use in industrial production, which entails risk of human exposure. Here, female C57BL/6J mice were exposed to 2, 6, and 18 µg (0.12, 0.35 and 1.1 mg/kg bw) of gallium phosphide (III-V) nanowires (99 nm diameter, 3.7 μm length) by intratracheal instillation and the toxicity was investigated 1, 3, 28 days and 3 months after exposure. Mitsui-7 multi-walled carbon nanotubes and carbon black Printex 90 nanoparticles were used as benchmark nanomaterials. Results: Gallium phosphide nanowires induced genotoxicity in bronchoalveolar lavage cells and acute inflammation with eosinophilia observable both in bronchoalveolar lavage and lung tissue (1 and 3 days post-exposure). The inflammatory response was comparable to the response following exposure to Mitsui-7 multi-walled carbon nanotubes at similar dose levels. The nanowires underwent partial dissolution in the lung resulting in thinner nanowires, with an estimated in vivo half-life of 3 months. Despite the partial dissolution, nanowires were detected in lung, liver, spleen, kidney, uterus and brain 3 months after exposure. Conclusion: Pulmonary exposure to gallium phosphide nanowires caused similar toxicological effects as the multi-walled carbon nanotube Mitsui-7. Graphical Abstract: [Figure not available: see fulltext.]
|
|
| 5. |
|
|
| 6. |
- Gällentoft, Lina, et al.
(författare)
-
Impact of degradable nanowires on long-term brain tissue responses
- 2016
-
Ingår i: Journal of Nanobiotechnology. - : Springer Science and Business Media LLC. - 1477-3155. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: A promising approach to improve the performance of neural implants consists of adding nanomaterials, such as nanowires, to the surface of the implant. Nanostructured interfaces could improve the integration and communication stability, partly through the reduction of the cell-to-electrode distance. However, the safety issues of implanted nanowires in the brain need to be evaluated and understood before nanowires can be used on the surface of implants for long periods of time. To this end we here investigate whether implanted degradable nanowires offer any advantage over non-degradable nanowires in a long-term in vivo study (1 year) with respect to brain tissue responses. Results: The tissue response after injection of degradable silicon oxide (SiOx)-coated gallium phosphide nanowires and biostable hafnium oxide-coated GaP nanowires into the rat striatum was compared. One year after nanowire injection, no significant difference in microglial or astrocytic response, as measured by staining for ED1 and glial fibrillary acidic protein, respectively, or in neuronal density, as measured by staining for NeuN, was found between degradable and biostable nanowires. Of the cells investigated, only microglia cells had engulfed the nanowires. The SiOx-coated nanowire residues were primarily seen in aggregated hypertrophic ED1-positive cells, possibly microglial cells that have fused to create multinucleated giant cells. Occasionally, degradable nanowires with an apparently intact shape were found inside single, small ED1-positive cells. The biostable nanowires were found intact in microglia cells of both phenotypes described. Conclusion: The present study shows that the degradable nanowires remain at least partly in the brain over long time periods, i.e. 1 year; however, no obvious bio-safety issues for this degradable nanomaterial could be detected.
|
|
| 7. |
- Hebisch, Elke, et al.
(författare)
-
Nanostraw-Assisted Cellular Injection of Fluorescent Nanodiamonds via Direct Membrane Opening
- 2021
-
Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 17:7
-
Tidskriftsartikel (refereegranskat)abstract
- Due to their stable fluorescence, biocompatibility, and amenability to functionalization, fluorescent nanodiamonds (FND) are promising materials for long term cell labeling and tracking. However, transporting them to the cytosol remains a major challenge, due to low internalization efficiencies and endosomal entrapment. Here, nanostraws in combination with low voltage electroporation pulses are used to achieve direct delivery of FND to the cytosol. The nanostraw delivery leads to efficient and rapid FND transport into cells compared to when incubating cells in a FND-containing medium. Moreover, whereas all internalized FND delivered by incubation end up in lysosomes, a significantly larger proportion of nanostraw-injected FND are in the cytosol, which opens up for using FND as cellular probes. Furthermore, in order to answer the long-standing question in the field of nano-biology regarding the state of the cell membrane on hollow nanostructures, live cell stimulated emission depletion (STED) microscopy is performed to image directly the state of the membrane on nanostraws. The time-lapse STED images reveal that the cell membrane opens entirely on top of nanostraws upon application of gentle electrical pulses, which supports the hypothesis that many FND are delivered directly to the cytosol, avoiding endocytosis and lysosomal entrapment.
|
|
| 8. |
- Johansson, Therese B., et al.
(författare)
-
Sub-Nanomolar Detection of Oligonucleotides Using Molecular Beacons Immobilized on Lightguiding Nanowires
- 2024
-
Ingår i: Nanomaterials. - 2079-4991. ; 14:5
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of oligonucleotides is a central step in many biomedical investigations. The most commonly used methods for detecting oligonucleotides often require concentration and amplification before detection. Therefore, developing detection methods with a direct read-out would be beneficial. Although commonly used for the detection of amplified oligonucleotides, fluorescent molecular beacons have been proposed for such direct detection. However, the reported limits of detection using molecular beacons are relatively high, ranging from 100 nM to a few µM, primarily limited by the beacon fluorescence background. In this study, we enhanced the relative signal contrast between hybridized and non-hybridized states of the beacons by immobilizing them on lightguiding nanowires. Upon hybridization to a complementary oligonucleotide, the fluorescence from the surface-bound beacon becomes coupled in the lightguiding nanowire core and is re-emitted at the nanowire tip in a narrower cone of light compared with the standard 4π emission. Prior knowledge of the nanowire positions allows for the continuous monitoring of fluorescence signals from each nanowire, which effectively facilitates the discrimination of signals arising from hybridization events against background signals. This resulted in improved signal-to-background and signal-to-noise ratios, which allowed for the direct detection of oligonucleotides at a concentration as low as 0.1 nM.
|
|
| 9. |
- Lard, Mercy, et al.
(författare)
-
Biosensing using arrays of vertical semiconductor nanowires : mechanosensing and biomarker detection
- 2019
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 30:21
-
Tidskriftsartikel (refereegranskat)abstract
- Due to their high aspect ratio and increased surface-to-foot-print area, arrays of vertical semiconductor nanowires are used in numerous biological applications, such as cell transfection and biosensing. Here we focus on two specific valuable biosensing approaches that, so far, have received relatively limited attention in terms of their potential capabilities: cellular mechanosensing and lightguiding-induced enhanced fluorescence detection. Although proposed a decade ago, these two applications for using vertical nanowire arrays have only very recently achieved significant breakthroughs, both in terms of understanding their fundamental phenomena, and in the ease of their implementation. We review the status of the field in these areas and describe significant findings and potential future directions.
|
|
| 10. |
- Lard, Mercy, et al.
(författare)
-
Use of dielectrophoresis for directing T cells to microwells before nanostraw transfection : modelling and experiments
- 2022
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 12:47, s. 30295-30303
-
Tidskriftsartikel (refereegranskat)abstract
- Nanostraw substrates have great potential for achieving minimally invasive cell transfection. Cells located on the nanostraw substrate are subjected to mild DC electric pulses applied across the nanostraw substrate, which open pores in the cell membrane on top of the nanostraws and drives charged cargo through these pores via electrophoresis. However, with this method, the current may leak through uncovered nanostraws, thereby decreasing the desired effect in the cell-covered nanostraws. A minimization of the number of uncovered nanostraws could be achieved by high cell coverage, but this is challenging when working with small cell populations. Nanostraw substrates of smaller area could be covered by smaller cell populations but are hard to integrate into fluidics systems. Here, we use simulations and experiments to show that this issue can be addressed by covering the nanostraw substrate with an insulating layer containing pores of similar size to cells. The pores act as traps into which cells can be guided using dielectrophoresis, ensuring a high degree of occupancy while maintaining a high cell viability, even if the total number of cells is low.
|
|
