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Publications (10 of 246) Show all publications
Wani, I. H., Jafri, S. H., Wärnå, J., Hayat, A., Li, H., Shukla, V. A., . . . Leifer, K. (2019). A sub 20 nm metal-conjugated molecule junction acting as a nitrogen dioxide sensor. Nanoscale, 11(14), 6571-6575
Open this publication in new window or tab >>A sub 20 nm metal-conjugated molecule junction acting as a nitrogen dioxide sensor
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 14, p. 6571-6575Article in journal (Refereed) Published
Abstract [en]

The interaction of a gas molecule with a sensing material causes the highest change in the electronic structure of the latter, when this material consists of only a few atoms. If the sensing material consists of a short, conductive molecule, the sensing action can be furthermore probed by connecting such molecules to nanoelectrodes. Here, we report that NO2 molecules that adhere to 4,4'-biphenyldithiol (BPDT) bound to Au surfaces lead to a change of the electrical transmission of the BPDT. The related device shows reproducible, stable measurements and is so far the smallest (<20 nm) gas sensor. It demonstrates modulation of charge transport through molecules upon exposure to nitrogen dioxide down to concentrations of 55 ppb. We have evaluated several devices and exposure conditions and obtained a close to linear dependence of the sensor response on the gas concentration.

National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-381056 (URN)10.1039/c8nr08417c (DOI)000464454400007 ()30916070 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationGöran Gustafsson Foundation for Research in Natural Sciences and MedicineCarl Tryggers foundation Swedish Energy AgencySwedish Foundation for Strategic Research
Available from: 2019-04-03 Created: 2019-04-03 Last updated: 2019-05-03Bibliographically approved
Han, Y., Li, H., Jafri, S. H., Ossipov, D. A., Hilborn, J. & LEIFER, K. (2019). Graphene Based Mechanical Biosensor by Employing Non-covalent Stacking Functionalization.
Open this publication in new window or tab >>Graphene Based Mechanical Biosensor by Employing Non-covalent Stacking Functionalization
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2019 (English)In: Article in journal, News item (Other academic) Submitted
Abstract [en]

Herein we demonstrate a novel methodology to achieve mechanical biosensor by employing the distinguished interaction forces between the atomic force microscope (AFM) probe and sensor surfaces as the response signal. This mechanical biosensor is fabricated by utilizing the non-covalent π-π stacking of pyrene-maltose onto graphene surfaces with Concanavalin A (Con A) as a target protein. The atomic resolution scanning tunneling microscopy (STM) images indicate the successful formation of the self-assembled and densely packed pyrene-maltose layer on the sensor surface, which gives distinct atomic lattice structure as compared to pristine graphene. This mechanical biosensor exhibits detection of Con A with the sensitivity down to nanomolar level. Therefore, this proposed mechanical biosensor has the potential to be employed in a variety of bio-sensing applications.

National Category
Nano Technology Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-378559 (URN)
Available from: 2019-03-06 Created: 2019-03-06 Last updated: 2019-04-24
Henning, D. F., Merkl, P., Yun, C., Iovino, F., Xie, L., Mouzourakis, E., . . . Sotiriou, G. A. (2019). Luminescent CeO2:Eu3+ nanocrystals for robust in situ H2O2 real-time detection in bacterial cell cultures. Biosensors & bioelectronics, 132, 286-293
Open this publication in new window or tab >>Luminescent CeO2:Eu3+ nanocrystals for robust in situ H2O2 real-time detection in bacterial cell cultures
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2019 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 132, p. 286-293Article in journal (Refereed) Published
Abstract [en]

Hydrogen peroxide (H2O2) quantification in biomedicine is valuable as inflammation biomarker but also in assays employing enzymes that generate or consume H2O2 linked to a specific biomarker. Optical H2O2 detection is typically performed through peroxidase-coupled reactions utilizing organic dyes that suffer, however, from poor stability/reproducibility and also cannot be employed in situ in dynamic complex cell cultures to monitor H2O2 levels in real-time. Here, we utilize enzyme-mimetic CeO2 nanocrystals that are sensitive to H2O2 and study the effect of H2O2 presence on their electronic and luminescent properties. We produce and dope with Eu3+ these particles in a single-step by flame synthesis and directly deposit them on Si and glass substrates to fabricate nanoparticle layers to monitor in real-time and in situ the H2O2 concentrations generated by Streptococcus pneumoniae clinical isolates. Furthermore, the small CeO2:Eu3+ nanocrystals are combined in a single-step with larger, non-responsive Y2O3:Tb3+ nanoparticles during their double-nozzle flame synthesis to engineer hybrid luminescent nanoaggregates as ratiometric robust biosensors. We demonstrate the functionality of these biosensors by monitoring their response in the presence of a broad range of H2O2 concentrations in vitro from S. pneumoniae, highlighting their potential for facile real-time H2O2 detection in vitro in cell cultures.

Place, publisher, year, edition, pages
ELSEVIER ADVANCED TECHNOLOGY, 2019
Keywords
Nanozymes, Rare-earth doped nanoparticles, Hydrogen peroxide, Flame nanoparticle synthesis
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-382822 (URN)10.1016/j.bios.2019.03.012 (DOI)000464296300033 ()30884315 (PubMedID)
Funder
EU, European Research Council, 758705Swedish Research Council, 2016-03471Åke Wiberg Foundation
Available from: 2019-05-06 Created: 2019-05-06 Last updated: 2019-05-06Bibliographically approved
Han, Y., Qiu, Z., Nawale, G. N., Varghese, O. P., Hilborn, J., Tian, B. & Leifer, K. (2019). MicroRNA detection based on duplex-specific nuclease-assisted target recycling and gold nanoparticle/graphene oxide nanocomposite-mediated electrocatalytic amplification. Biosensors & bioelectronics, 127, 188-193
Open this publication in new window or tab >>MicroRNA detection based on duplex-specific nuclease-assisted target recycling and gold nanoparticle/graphene oxide nanocomposite-mediated electrocatalytic amplification
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2019 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 127, p. 188-193Article in journal (Refereed) Published
Abstract [en]

DNA technology based bio-responsive nanomaterials have been widely studied as promising tools for biomedical applications. Gold nanoparticles (AuNPs) and graphene oxide (GO) sheets are representative zero- and two-dimensional nanomaterials that have long been combined with DNA technology for point-of-care diagnostics. Herein, a cascade amplification system based on duplex-specific nuclease (DSN)-assisted target recycling and electrocatalytic water-splitting is demonstrated for the detection of microRNA. Target microRNAs can form DNA: RNA heteroduplexes with DNA probes on the surface of AuNPs, which can be hydrolyzed by DSN. MicroRNAs are preserved during the reaction and released into the suspension for the digestion of multiple DNA probes. After the DSN-based reaction, AuNPs are collected and mixed with GO to form AuNP/GO nanocomposite on an electrode for the following electrocatalytic amplification. The utilization of AuNP/GO nanocomposite offers large surface area, exceptional affinity to water molecules, and facilitated mass diffusion for the water-splitting reaction. For let-7b detection, the proposed biosensor achieved a limit detection of 1.5 fM in 80 min with a linear detection range of approximately four orders of magnitude. Moreover, it has the capability of discriminating non-target microRNAs containing even single-nucleotide mismatches, thus holding considerable potential for clinical diagnostics.

Keywords
Gold nanoparticles, Graphene oxide, MicroRNA detection, Electrocatalytic amplification, Duplex-specific nuclease
National Category
Analytical Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-377203 (URN)10.1016/j.bios.2018.12.027 (DOI)000457508800026 ()30611105 (PubMedID)
Funder
Swedish Research Council, 2016-05259Knut and Alice Wallenberg FoundationEU, Horizon 2020, 713683
Available from: 2019-02-25 Created: 2019-02-25 Last updated: 2019-04-24Bibliographically approved
Omanakuttan, G., Martinez Sacristan, O., Marcinkevicius, S., Uzdavinys, T. K., Jimenez, J., Ali, H., . . . Sun, Y.-T. (2019). Optical and interface properties of direct InP/Si heterojunction formed by corrugated epitaxial lateral overgrowth. Optical Materials Express, 9(3), 1488-1500
Open this publication in new window or tab >>Optical and interface properties of direct InP/Si heterojunction formed by corrugated epitaxial lateral overgrowth
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2019 (English)In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 9, no 3, p. 1488-1500Article in journal (Refereed) Published
Abstract [en]

We fabricate and study direct InP/Si heterojunction by corrugated epitaxial lateral overgrowth (CELOG). The crystalline quality and depth-dependent charge carrier dynamics of InP/Si heterojunction are assessed by characterizing the cross-section of grown layer by low-temperature cathodoluminescence, time-resolved photoluminescence and transmission electron microscopy. Compared to the defective seed InP layer on Si, higher intensity band edge emission in cathodoluminescence spectra and enhanced carrier lifetime of InP are observed above the CELOG InP/Si interface despite large lattice mismatch, which are attributed to the reduced threading dislocation density realized by the CELOG method.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-379937 (URN)10.1364/OME.9.001488 (DOI)000460134500051 ()
Funder
Swedish Energy AgencySwedish Research Council
Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-03-26Bibliographically approved
Ali, H., Warnatz, T., Xie, L., Hjörvarsson, B. & Leifer, K. (2019). Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS. Ultramicroscopy, 196, 192-196
Open this publication in new window or tab >>Quantitative EMCD by use of a double aperture for simultaneous acquisition of EELS
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2019 (English)In: Ultramicroscopy, ISSN 0304-3991, E-ISSN 1879-2723, Vol. 196, p. 192-196Article in journal (Refereed) Published
Abstract [en]

The weak signal strength in electron magnetic circular dichroism (EMCD) measurements remains one of the main challenges in the quantification of EMCD related EELS spectra. As a consequence, small variations in peak intensity caused by changes of background intervals, choice of method for extraction of signal intensity and equally differences in sample quality can cause strong changes in the EMCD signal. When aiming for high resolution quantitative EMCD, an additional difficulty consists in the fact that the two angular resolved EELS spectra needed to obtain the EMCD signal are taken at two different instances and it cannot be guaranteed that the acquisition conditions for these two spectra are identical.  Here, we present an experimental setup where we use a double hole aperture in the transmission electron microscope to obtain the EMCD signal in a single acquisition. This geometry allows for the parallel acquisition of the two electron energy loss spectra (EELS) under exactly the same conditions. We also compare the double aperture acquisition mode with the qE acquisition mode which has been previously used for parallel acquisition of EMCD. We show that the double aperture mode not only offers better signal to noise ratio as compared to qE mode but also allows for much higher acquisition times to significantly improve the signal quality which is crucial for quantitative analysis of the magnetic moments.

National Category
Other Materials Engineering
Research subject
Materials Science
Identifiers
urn:nbn:se:uu:diva-364715 (URN)10.1016/j.ultramic.2018.10.012 (DOI)000451180800026 ()30439606 (PubMedID)
Funder
Swedish Research Council, C0367901Swedish Research Council, 2016-05259Knut and Alice Wallenberg Foundation
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2019-01-28Bibliographically approved
Irkhina, A., Levcenko, S., Xie, L., Leifer, K. & Unold, T. (2019). Radiative emission from Cu2ZnSnS4/ZnSn core/shell nanocrystals. Journal of Materials Chemistry C, 7(20), 6129-6133
Open this publication in new window or tab >>Radiative emission from Cu2ZnSnS4/ZnSn core/shell nanocrystals
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2019 (English)In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 7, no 20, p. 6129-6133Article in journal (Refereed) Published
Abstract [en]

Kesterite Cu2ZnSnS4 (CZTS) nanocrystals so far have been found to luminesce neither at room temperature nor at low temperature. Here a core-shell architecture for kesterite CZTS nanocrystals is demonstrated by applying a ZnSn-alloy shell overcoating approach. These CZTS/ZnSn nanocrystals show luminescence emission at 1.05 eV, which is red-shifted by about 0.4 eV from the absorption onset and is attributed to a radiative transition involving a deep defect. Temperature-dependent photoluminescence measurements within a range of 20-200 K indicate the presence of a competing nonradiative channel with an activation energy of 50-60 meV.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-390604 (URN)10.1039/c9tc00904c (DOI)000472444800027 ()
Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Tian, B., Han, Y., Fock, J., Strömberg, M., Leifer, K. & Fougt Hansen, M. (2019). Self-Assembled Magnetic Nanoparticle−Graphene Oxide Nanotag for Optomagnetic Detection of DNA. Acs Applied Nano Materials, 2(3), pp. 1683-1690
Open this publication in new window or tab >>Self-Assembled Magnetic Nanoparticle−Graphene Oxide Nanotag for Optomagnetic Detection of DNA
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2019 (English)In: Acs Applied Nano Materials, ISSN 2574-0970, Vol. 2, no 3, p. 1683-1690Article in journal, News item (Refereed) Published
Abstract [en]

In this work, a two-dimensional self-assembled magnetic nanoparticle–graphene oxide (MNP-GO) nanocomposite is reported for the detection of DNA. Single-stranded DNA (ssDNA) coils, generated through a rolling circle amplification (RCA) reaction triggered by the hybridization of target oligos and padlock probes, have a strong interaction with MNP-GO nanotags through several mechanisms including π–π stacking, hydrogen bonding, van der Waals, electrostatic, and hydrophobic interactions. This interaction leads to a hydrodynamic size increase or aggregation of MNP-GO nanotags, which can be detected by a simple optomagnetic setup. Due to the high shape anisotropy, MNP-GO nanotags provide stronger optomagnetic signal than individual MNPs. Moreover, the avoidance of DNA probes (i.e., short ssDNA sequences as the biosensing receptor) provides easier material preparation and lower measurement cost. From real-time measurements of interactions between MNP-GO and RCA products amplified from a highly conserved Escherichia coli 16S rDNA sequence, a limit of detection of 2 pM was achieved with a total assay time of 90 min. Although the nonspecific binding force between GO and ssDNA is much weaker than the specific base-pairing force in a DNA duplex, the proposed method provides a detection limit similar to DNA probe-based magnetic biosensors, which can be ascribed to the abundant binding sites between GO and ssDNA. In addition, for target concentrations higher than 100 pM, the MNP-GO nanotags can be applied for a qualitative naked eye detection strategy based on nanotag–ssDNA flocculation.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Magnetic nanoparticles; graphene oxide; rolling circle amplification; single stranded DNA detection; optomagnetic sensing
National Category
Nano Technology Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-378551 (URN)10.1021/acsanm.9b00127 (DOI)000462554000061 ()
Available from: 2019-03-06 Created: 2019-03-06 Last updated: 2019-04-24Bibliographically approved
Tian, B., Han, Y., Fock, J., Strömberg, M., Leifer, K. & Fougt Hansen, M. (2019). Self-Assembled Magnetic Nanoparticle−Graphene Oxide Nanotag for Optomagnetic Detection of DNA. Acs Applied Nano Materials, 2(3), 1683-1690
Open this publication in new window or tab >>Self-Assembled Magnetic Nanoparticle−Graphene Oxide Nanotag for Optomagnetic Detection of DNA
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2019 (English)In: Acs Applied Nano Materials, ISSN 2574-0970, Vol. 2, no 3, p. 1683-1690Article in journal (Refereed) Published
Abstract [en]

In this work, a two-dimensional self-assembled magnetic nanoparticle–graphene oxide (MNP-GO) nanocomposite is reported for the detection of DNA. Single-stranded DNA (ssDNA) coils, generated through a rolling circle amplification (RCA) reaction triggered by the hybridization of target oligos and padlock probes, have a strong interaction with MNP-GO nanotags through several mechanisms including π–π stacking, hydrogen bonding, van der Waals, electrostatic, and hydrophobic interactions. This interaction leads to a hydrodynamic size increase or aggregation of MNP-GO nanotags, which can be detected by a simple optomagnetic setup. Due to the high shape anisotropy, MNP-GO nanotags provide stronger optomagnetic signal than individual MNPs. Moreover, the avoidance of DNA probes (i.e., short ssDNA sequences as the biosensing receptor) provides easier material preparation and lower measurement cost. From real-time measurements of interactions between MNP-GO and RCA products amplified from a highly conserved Escherichia coli 16S rDNA sequence, a limit of detection of 2 pM was achieved with a total assay time of 90 min. Although the nonspecific binding force between GO and ssDNA is much weaker than the specific base-pairing force in a DNA duplex, the proposed method provides a detection limit similar to DNA probe-based magnetic biosensors, which can be ascribed to the abundant binding sites between GO and ssDNA. In addition, for target concentrations higher than 100 pM, the MNP-GO nanotags can be applied for a qualitative naked eye detection strategy based on nanotag–ssDNA flocculation.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
Keywords
Magnetic nanoparticles; graphene oxide; rolling circle amplification; single stranded DNA detection; optomagnetic sensing
National Category
Nano Technology Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-378551 (URN)10.1021/acsanm.9b00127 (DOI)000462554000061 ()
Available from: 2019-03-06 Created: 2019-04-24 Last updated: 2019-04-24Bibliographically approved
Phadatare, M., Patil, R., Blomquist, N., Forsberg, S., Örtegren, J., Hummelgård, M., . . . Olin, H. (2019). Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries. Scientific Reports, 9, Article ID 14621.
Open this publication in new window or tab >>Silicon-Nanographite Aerogel-Based Anodes for High Performance Lithium Ion Batteries
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 14621Article in journal (Refereed) Published
Abstract [en]

To increase the energy storage density of lithium-ion batteries, silicon anodes have been explored due to their high capacity. One of the main challenges for silicon anodes are large volume variations during the lithiation processes. Recently, several high-performance schemes have been demonstrated with increased life cycles utilizing nanomaterials such as nanoparticles, nanowires, and thin films. However, a method that allows the large-scale production of silicon anodes remains to be demonstrated. Herein, we address this question by suggesting new scalable nanomaterial-based anodes. Si nanoparticles were grown on nanographite flakes by aerogel fabrication route from Si powder and nanographite mixture using polyvinyl alcohol (PVA). This silicon-nanographite aerogel electrode has stable specific capacity even at high current rates and exhibit good cyclic stability. The specific capacity is 455 mAh g(-1) for 200th cycles with a coulombic efficiency of 97% at a current density 100 mA g(-1).

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2019
National Category
Materials Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-396718 (URN)10.1038/s41598-019-51087-y (DOI)000489555900015 ()31601920 (PubMedID)
Funder
Swedish Energy Agency, 2014-001912Swedish Energy Agency, 40466-1Knowledge FoundationThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IB-2018 7535Vinnova, 2017-03616
Available from: 2019-11-08 Created: 2019-11-08 Last updated: 2019-11-08Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8360-1877

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