| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Han, Yuanyuan
(författare)
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Biosensing platforms using graphene based bioreactive nanostructures with various dimensions
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanomaterials have brought new aspects and improvements to the biosensing field due to their unique physical and chemical properties that are not shown in the bulk state. This thesis focuses on concepting, developing and testing of biosensors where nanomaterials including graphene gold nanoparticles (AuNPs) and magnetic nanoparticles (MNPs) constitute the biosensors. The motivation is to improve the properties of biosensors for protein and nucleic acids by using the nanomaterials’ high surface volume ratio, their unique electrical properties, their good stability and biocompatibility.The synthesis of well controlled hybrid materials was essential to obtain well performing nucleic acids sensors, whereas a protein sensor contained mainly graphene and organic molecules. The nanomechanical measurements were applied on pyrene-maltose functionalized graphene surfaces after incubating them with the protein. When the Concanavalin A was captured by the pyrene-maltose, the adhesion force of biosensor surface increased significantly. This detection principle was employed to quantify the Concanavalin A attachment to the surface sensitively.In the development of the eletrocatalytic microRNA sensor, AuNPs were packaged into graphene oxide (GO) sheets to form three-dimensional network structures that both guide the electrical current and increase the surface area of the electrodes. Prior to the assembly of these GO-AuNPs hybrid materials, a duplex-specific nuclease-assisted target recycling reaction was employed for opening the surface of the DNA functionalized AuNPs. The electrocatalytical water splitting activity increased with the fraction of the AuNP surface and thus with the activity of the nuclease-assisted target recycling reaction.Owing to the high shape anisotropy of graphene, a two-dimensional optomagnetic label GO-MNP nanohybrid was investigated for DNA detection. The DNA coils that were generated through rolling circle amplification absorbed on GO-MNP nanohybrid, leading to a hydrodynamic size increase or aggregation of the proposed nanolabels that can be detected by an optomagnetic sensor. An MNP assembly-based microRNA biosensing strategy is also included in the thesis. DNA scaffolds of the MNP assemblies contain DNAzyme substrate and thus can form cleavage catalytic structures in the presence of microRNA, leading to the disintegration of assemblies. The proposed nanomaterials based biosensing platforms show great potential in the clinical and biomedical applications.
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| 3. |
- Han, Yuanyuan, et al.
(författare)
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Flexible conductive silk-PPy hydrogel toward wearable electronic strain sensors
- 2022
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Ingår i: Biomedical Materials. - : IOP Publishing Ltd. - 1748-6041 .- 1748-605X. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- Conductive hydrogels have been studied as promising materials for the flexible and wearable bioelectronics, because of their unique electrical and mechanical properties. Addition of conducting polymers in biomaterial-based hydrogel matrix is a simple yet effective way to construct hydrogels with good conductivity and flexibility. In this work, a conductive hydrogel composed by a silk hydrogel and a conducting polymer, polypyrrole (PPy), is developed via in situ polymerization of pyrrole into the silk fibroin network. The silk-PPy hydrogel shows high conductivity (26 S m(-1)), as well as sensitive and fast responses to corresponding conformation changes. Taking advantages of these properties, flexible and wearable strain sensors are proposed for the monitoring of various body movements, which can detect both the large and subtle human motions with good sensitivity, reproducibility and stability. The hybridization of biomaterials and conducting polymers endows the multifunctions of the conductive hydrogels, thus showing considerable potentials in the advancement of the wearable electronics.
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| 4. |
- Han, Yuanyuan, et al.
(författare)
-
Graphene Based Mechanical Biosensor by Employing Non-covalent Stacking Functionalization
- 2019
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 5. |
- Han, Yuanyuan, et al.
(författare)
-
MicroRNA detection based on duplex-specific nuclease-assisted target recycling and gold nanoparticle/graphene oxide nanocomposite-mediated electrocatalytic amplification
- 2019
-
Ingår i: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 127, s. 188-193
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
- Han, Yuanyuan, et al.
(författare)
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Optimization and analysis of pyrene-maltose functionalized graphene surfaces for Con A detection
- 2020
-
Ingår i: Applied Surface Science. - : ELSEVIER. - 0169-4332 .- 1873-5584. ; 510
-
Tidskriftsartikel (refereegranskat)abstract
- Utilizing the non-covalent pi-pi stacking of pyrene functionalized molecules onto graphene surfaces has achieved great success in the detection of various bio-objects, while the fundamental investigations on surface modifications stills remain rarely exploited. Here, we report the nano and atomic scale analysis of the pi-pi stacking functionalized graphene surface regarding to its surface topography, molecular self-assembly as well as process optimizations. The 'amphipathic' molecule, pyrene-maltose, is used for the non-covalent functionalization of graphene and systematical analysis is performed to understand the influence of different solvents on the molecular surface arrangement. Atomic force microscopy (AFM) and spectroscopy analysis indicate the successful formation of pyrene-maltose layer on graphene surface and it is further confirmed by scanning tunneling microscopy, depicting the self-assembled and densely packed pyrene-maltose layer that give distinguished and ordered diamond-shape lattice as compared to triangular lattice in pristine graphene. We also demonstrated that the interfacial adhesion forces between the AFM probe and the functionalized surfaces allow the detection of the lectin protein Concavalin A through selective absorption. This work provides essential evidence of the pi-pi interactions between pyrene molecules and graphene, and the AFM based adhesion measurement also has the potential to be employed in a variety of bio-detection applications.
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| 7. |
- Johansson, Fredrik, et al.
(författare)
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Tailoring ultra-fast charge transfer in MoS2
- 2020
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 22:18, s. 10335-10342
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Tidskriftsartikel (refereegranskat)abstract
- Charge transfer dynamics are of importance in functional materials used in devices ranging from transistors to photovoltaics. The understanding of charge transfer in particular of how fast electrons tunnel away from an excited state and where they end up, is necessary to tailor materials used in devices. We have investigated charge transfer dynamics in different forms of the layered two-dimensional material molybdenum disulphide (MoS2, in single crystal, nanocrystalline particles and crystallites in a reduced graphene oxide network) using core-hole clock spectroscopy. By recording the electrons in the sulphur KLL Auger electron kinetic energy range we have measured the prevalence of localised and delocalised decays from a state created by core excitation using X-rays. We show that breaking the crystal symmetry of the single crystal into either particles or sheets causes the charge transfer from the excited state to occur faster, even more so when incorporating it in a graphene oxide network. The interface between the MoS2 and the reduced graphene oxide forms a Schottky barrier which changes the ratio between local and delocalised decays creating two distinct regions in the charge transfer dependent on the energy of the excited electron. Thereby we show that ultra-fast charge transfer in MoS2 can be tailored, a result which can be used in the design of emergent devices.
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| 8. |
- Li, Hu, et al.
(författare)
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Dyes as Labels in Biosensing
- 2021
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Ingår i: Dyes and Pigments. - London : IntechOpen. - 9781839686153
-
Bokkapitel (refereegranskat)abstract
- Investigation and evaluation of dyes play a vital role in the process of introduction novel labels and their corresponding sensing methods, which signify opportunities for the development of biosensors. This chapter introduces applications of various dyes as labels in biosensing. Bio-recognition molecules with dyes transduce biological information into measurable optical, electrochemical, magnetic or other kinds of signals for quantification. The dyes used in this field were summarized and reviewed according to their signal types, namely colorimetric, fluorescent and electrochemical. Some dyes can transduce signals between multiple physical signals. For some most important dyes, detailed descriptions were given focused on their unique properties, labeling methods and sensing mechanisms.
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| 9. |
- Li, Hu, 1986-, et al.
(författare)
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Enhanced gas sensing performance of graphene/ZnS-CdS hetero-nanowires gas sensor synthesized by Langmuir-Blodgett self-assembly method
- 2017
-
Ingår i: Journal of Physics Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 922
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Tidskriftsartikel (refereegranskat)abstract
- Graphene is a promising material in the field of solid-state gas sensors due to the unique two-dimensional structure. Here, we have shown by fabricating graphene/ZnS-CdS hetero-nanowire structure, the gas sensor sensitivity has a two-fold increase to 20% under 15 ppm gaseous concentration compared to a 10% response in pristine graphene. Spectroscopy and microscopy analysis indicate that the semi-conducting ZnS-CdS hetero-nanowires are 2 nm wide and densely packed on top of graphene. By combining UV illumination, the device approaches a fast response/recovery and high gas sensitivity, thus has a potential to be used in a detection of wide range of gases.
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| 10. |
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| 11. |
- Li, Hu, 1986-, et al.
(författare)
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Fabrication of BP2T functionalized graphene via non-covalent π-π stacking interactions for enhanced ammonia detection
- 2021
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 11:57, s. 35982-35987
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene has stimulated great enthusiasm in a variety of fields, while its chemically inert surface still remains challenging for functionalization towards various applications. Herein, we report an approach to fabricate non-covalently functionalized graphene by employing pi-pi stacking interactions, which has potentialities for enhanced ammonia detection. 5,5 '-Di(4-biphenylyl)-2,2 '-bithiophene (BP2T) molecules are used in our work for the non-covalent functionalization through strong pi-pi interactions of aromatic structures with graphene, and systematic investigations by employing various spectroscopic and microscopic characterization methods confirm the successful non-covalent attachment of the BP2T on the top of graphene. From our gas sensing experiments, the BP2T functionalized graphene is promising for ammonia sensing with a 3-fold higher sensitivity comparing to that of the pristine graphene, which is mainly attributed to the enhanced binding energy between the ammonia and BP2T molecules derived by employing the Langmuir isotherm model. This work provides essential evidence of the pi-pi stacking interactions between graphene and aromatic molecules, and the reported approach also has the potential to be widely employed in a variety of graphene functionalizations for chemical detection.
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| 12. |
- Li, Hu, et al.
(författare)
-
Photoluminescent Semiconducting Graphene Nanoribbons via Longitudinally Unzipping Single-Walled Carbon Nanotubes
- 2021
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:44, s. 52892-52900
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Tidskriftsartikel (refereegranskat)abstract
- The lack of a sizeable band gap has so far prevented graphene from building effective electronic and optoelectronic devices despite its numerous exceptional properties. Intensive theoretical research reveals that a band gap larger than 1 eV can only be achieved in sub-3 nm wide graphene nanoribbons (GNRs), but real fabrication of such ultranarrow GNRs still remains a critical challenge. Herein, we demonstrate an approach for the synthesis of ultranarrow and photoluminescent semiconducting GNRs by longitudinally unzipping single-walled carbon nanotubes. Atomic force microscopy reveals the unzipping process, and the resulting 2.2 nm wide GNRs are found to emit strong and sharp photoluminescence at similar to 685 nm, demonstrating a very desirable semiconducting nature. This band gap of 1.8 eV is further confirmed by follow-up photoconductivity measurements, where a considerable photocurrent is generated, as the excitation wavelength becomes shorter than 700 nm. More importantly, our fabricated GNR field-effect transistors (FETs), by employing the hexagonal boron nitride-encapsulated heterostructure to achieve edge-bonded contacts, demonstrate a high current on/off ratio beyond 105 and carrier mobility of 840 cm(2)/V s, approaching the theoretical scattering limit in semiconducting GNRs at room temperature. Especially, highly aligned GNR bundles with lengths up to a millimeter are also achieved by prepatterning a template, and the fabricated GNR bundle FETs show a high on/off ratio reaching 10(5), well-defined saturation currents, and strong light-emitting properties. Therefore, GNRs produced by this method open a door for promising applications in graphene-based electronics and optoelectronics.
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| 13. |
- Li, Hu, 1986-, et al.
(författare)
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Size-dependent elasticity of gold nanoparticle measured by atomic force microscope based nanoindentation
- 2019
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 115:5
-
Tidskriftsartikel (refereegranskat)abstract
- The elasticity is one of the key properties in gold nanoparticles (AuNPs) and plays an essential role in the process design and applications. In this work, we have proposed an Argon plasma based technique to obtain well dispersed and neat AuNPs without surface functional groups. Our investigation on the size-dependent elasticity focused on the AuNPs with the size ranging from 2 nm to 12 nm by using atomic force microscope based nanoindentation technique under the peakforce quantitative nanomechanical mapping mode. The results show clearly that when the AuNPs are smaller than 6 nm, there is a significant increase in the elasticity as the smallest nanoparticles displacing an elastic modulus of ~140 GPa. Our result provides important experimental evidence that contributes to a better understanding of the size-property relations as well as process design in AuNPs, and it also can be applied to measure the mechanical properties in a wide range of nano-objects.
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| 14. |
- Li, Ya, et al.
(författare)
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Click chemistry-based biopolymeric hydrogels for regenerative medicine
- 2021
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 16:2
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Forskningsöversikt (refereegranskat)abstract
- Click chemistry is not a single specific reaction, but describes ways of generating products which emulate examples in nature. Click reactions occur in one pot, are not disturbed by water, generate minimal and inoffensive byproducts, and are characterized by a high thermodynamic driving force, driving the reaction quickly and irreversibly towards a high yield of a single reaction product. As a result, over the past 15 years it has become a very useful bio-orthogonal method for the preparation of chemical cross-linked biopolymer-based hydrogel, in the presence of e.g. growth factors and live cells, or in-vivo. Biopolymers are renewable and non-toxic, providing a myriad of potential backbone toolboxes for hydrogel design. The goal of this review is to summarize recent advances in the development of click chemistry-based biopolymeric hydrogels, and their applications in regenerative medicine. In particular, various click chemistry approaches, including copper-catalyzed azide-alkyne cycloaddition reactions, copper-free click reactions (e.g. the Diels-Alder reactions, the strain-promoted azide-alkyne cycloaddition reactions, the radical mediated thiol-ene reactions, and the oxime-forming reactions), and pseudo-click reactions (e.g. the thiol-Michael addition reactions and the Schiff base reactions) are highlighted in the first section. In addition, numerous biopolymers, including proteins (e.g. collagen, gelatin, silk, and mucin), polysaccharides (e.g. hyaluronic acid, alginate, dextran, and chitosan) and polynucleotides (e.g. deoxyribonucleic acid), are discussed. Finally, we discuss biopolymeric hydrogels, cross-linked by click chemistry, intended for the regeneration of skin, bone, spinal cord, cartilage, and cornea. This article provides new insights for readers in terms of the design of regenerative medicine, and the use of biopolymeric hydrogels based on click chemistry reactions.
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| 15. |
- Li, Zheng, et al.
(författare)
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Inkjet Printed Disposable High-Rate On-Paper Microsupercapacitors
- 2022
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 32:1, s. 2108773-
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Tidskriftsartikel (refereegranskat)abstract
- On-paper microsupercapacitors (MSCs) are a key energy storage component for disposable electronics that are anticipated to essentially address the increasing global concern of electronic waste. However, nearly none of the present on-paper MSCs combine eco-friendliness with high electrochemical performance (especially the rate capacity). In this work, highly reliable conductive inks based on the ternary composite of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), graphene quantum dots and graphene are developed for scalable inkjet printing of compact (footprint area ≈ 20 mm2) disposable MSCs on commercial paper substrates. Without any post treatment, the printed patterns attain a sheet resistance as low as 4 Ω ▫−1. The metal-free all-solid-state MSCs exhibit a maximum areal capacitance > 2 mF cm−2 at a high scan rate of 1000 mV s−1, long cycle life (>95% capacitance retention after 10 000 cycles), excellent flexibility, and long service time. Remarkably, the “totally metal-free” MSC arrays are fully inkjet printed on paper substrates and also exhibit high rate performance. The life cycle assessment indicates that these printed devices have much lower eco-toxicity and global warming potential than other on-paper MSCs.
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| 16. |
- Liu, Shaohua, et al.
(författare)
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Synthesis of chiral TiO2 nanofibre with electron transition-based optical activity
- 2012
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 3, s. 1215-
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Tidskriftsartikel (refereegranskat)abstract
- The optical chirality induced at the absorption bands due to electronic exciton coupling of the transition dipole moments between chromophores in close proximity is ubiquitous in helical organic materials. However, inorganic materials with optical activity resulting from electronic transitions have not been explored. Here we report the synthesis of chiral TiO2 fibres via transcription of the helical structure of amino acid-derived amphiphile fibres through coordination bonding interactions between the organics and the TiO2 source. Upon calcination, the as-prepared amorphous TiO2 double-helical fibres with a pitch length of ~100 nm were converted to double-helical crystalline fibres with stacks of anatase nanocrystals in an epitaxial helical relationship. Both the amorphous and anatase crystalline helical TiO2 fibres exhibited optical response to circularly polarized light at the absorption edge around ~350 nm. This was attributed to the semiconductor TiO2-based electronic transitions from the valence band to the conduction band under an asymmetric electric field.
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| 17. |
- Lundstedt, Anna, et al.
(författare)
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White-light photoassisted covalent functionalization of graphene using 2-propanol
- 2017
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Ingår i: Small Methods. - : John Wiley & Sons. - 2366-9608. ; 1:11
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Tidskriftsartikel (refereegranskat)abstract
- Herein, a photochemical method for functionalization of graphene using 2-propanol is reported. The functionalization method which is catalyst-free operates at ambient temperature in neat 2-propanol under an inert atmosphere of argon. The equipment requirement is a white-light source for the irradiation. The same methodology when applied to kish graphite results in a novel material, exhibiting significantly higher wettability than the starting material according to water contact angle measurements. Furthermore, the materials generated from both graphene and kish graphite exhibit increased adhesion energy, attributed to the fixation of isopropyl alcohol fragments onto graphene and graphite, respectively. The presence of hydroxyl groups and the possibility for further reactions on the functionalized graphene material are demonstrated through a substitution reaction with thionyl chloride, where the hydroxyl groups are replaced with chlorides, as confirmed through X-ray photoelectron spectroscopy analysis.
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| 18. |
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| 19. |
- Qin, Tao, 1984-, et al.
(författare)
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A general strategy for template-free and low-cost synthesis of inorganic hollow spheres
- 2017
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910 .- 1873-328X. ; 319, s. 163-171
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Tidskriftsartikel (refereegranskat)abstract
- Inorganic hollow spheres have a great potential in many fields, such as calcium phosphate (Ca3(PO4)2) as carriers of active ingredients and local delivery. They are typically synthesized by the methods that reply on template-based strategies. However, the template residue and energy consumption during template removal are drawbacks. Currently developed template-free methods remain challenges such as time, cost and complicated procedures. In this paper, we introduce a general low-cost and template-free precipitation method with simple procedure. A series of inorganic hollow spheres, including calcium phosphate, calcium fluoride, strontium phosphate, strontium fluoride, barium phosphate and barium fluoride via magnesium were successfully synthesized, respectively. Based on these experimental results, a new model is proposed to explain the mechanism of the hollow inorganic spheres formation. This paper provides a general method to synthesize inorganic hollow spheres, which may have an important indication to other systems.
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| 20. |
- Qin, Tao, 1984-, et al.
(författare)
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A novel method to synthesize low-cost phosphate-based particles from natural water
- 2017
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Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 206, s. 178-181
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Tidskriftsartikel (refereegranskat)abstract
- Calcium phosphate (CaP) and magnesium phosphate (MgP) are widely used as biomaterials. A novel method for low-cost manufacturing of calcium phosphate spheres and magnesium phosphate micro particles was studied. The method focuses on novel strategies of utilizing seawater and lake water. In the natural water, the molar ratios of Mg/Ca are constant. The morphologies of the particles are determined by ratio of Ca/P. This simple method provides a prototype to synthesize low-cost inorganic spheres with natural water, which facilitate large-scale production.
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| 21. |
- Qin, Tao, 1984-, et al.
(författare)
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Template-free synthesis of phosphate-based spheres via modified supersaturated phosphate buffer solutions
- 2017
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Ingår i: Journal of materials science. Materials in medicine. - : SPRINGER. - 0957-4530 .- 1573-4838. ; 28:7
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Tidskriftsartikel (refereegranskat)abstract
- Modified supersaturated phosphate buffer solutions were used to synthesize phosphate-based spheres, including calcium phosphate (CaP), strontium phosphate (SrP) and barium phosphate (BaP). A series of ions concentrations in the modified phosphate buffer solutions were investigated in order to study their effects in precipitates morphologies. During synthesis, it was found that magnesium was the key factor in sphere formation. The morphologies of calcium phosphate, strontium phosphate and barium phosphate precipitates varied as the concentration of magnesium ions varied. When sufficient magnesium was provided, the precipitates appeared spherical, and the diameter was in range of 0.5-2 mu m. The morphologies, compositions and structure of spheres were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N-2 adsorption analysis. Moreover, the application of magnesium substituted calcium phosphate spheres in dentin tubules occlusion was investigated.
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| 22. |
- Qin, Tao, 1984-, et al.
(författare)
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The formation of calcium fluoride microspheres via solubility equilibrium
- 2017
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 43:16, s. 14521-14524
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Tidskriftsartikel (refereegranskat)abstract
- The focus of this study is on synthesis and mechanism of calcium fluoride (CaF2) spheres. Magnesium is the decisive factor in the formation of the spheres. The solubility product constant of Mg1-xCaxF2 is higher than those of CaF2 and MgF2. The structure of particles evolved to being spherical due to solubility equilibrium. The calcium fluoride spheres have great potential as dental materials in bleaching products.
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| 23. |
- Schweinsberg, Martin, et al.
(författare)
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Same data, different conclusions : Radical dispersion in empirical results when independent analysts operationalize and test the same hypothesis
- 2021
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Ingår i: Organizational Behavior and Human Decision Processes. - : Elsevier BV. - 0749-5978 .- 1095-9920. ; 165, s. 228-249
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Tidskriftsartikel (refereegranskat)abstract
- In this crowdsourced initiative, independent analysts used the same dataset to test two hypotheses regarding the effects of scientists' gender and professional status on verbosity during group meetings. Not only the analytic approach but also the operationalizations of key variables were left unconstrained and up to individual analysts. For instance, analysts could choose to operationalize status as job title, institutional ranking, citation counts, or some combination. To maximize transparency regarding the process by which analytic choices are made, the analysts used a platform we developed called DataExplained to justify both preferred and rejected analytic paths in real time. Analyses lacking sufficient detail, reproducible code, or with statistical errors were excluded, resulting in 29 analyses in the final sample. Researchers reported radically different analyses and dispersed empirical outcomes, in a number of cases obtaining significant effects in opposite directions for the same research question. A Boba multiverse analysis demonstrates that decisions about how to operationalize variables explain variability in outcomes above and beyond statistical choices (e.g., covariates). Subjective researcher decisions play a critical role in driving the reported empirical results, underscoring the need for open data, systematic robustness checks, and transparency regarding both analytic paths taken and not taken. Implications for orga-nizations and leaders, whose decision making relies in part on scientific findings, consulting reports, and internal analyses by data scientists, are discussed.
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| 24. |
- Sher, Omer, et al.
(författare)
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Analysis of molecular ligand functionalization process in nano-molecular electronic devices containing densely packed nano-particle functionalization shells
- 2022
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 33:25
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Tidskriftsartikel (refereegranskat)abstract
- Molecular electronic devices based on few and single-molecules have the advantage that the electronic signature of the device is directly dependent on the electronic structure of the molecules as well as of the electrode-molecule junction. In this work, we use a two-step approach to synthesise functionalized nanomolecular electronic devices (nanoMoED). In first step we apply an organic solvent-based gold nanoparticle (AuNP) synthesis method to form either a 1-dodecanethiol or a mixed 1-dodecanethiol/omega-tetraphenyl ether substituted 1-dodecanethiol ligand shell. The functionalization of these AuNPs is tuned in a second step by a ligand functionalization process where biphenyldithiol (BPDT) molecules are introduced as bridging ligands into the shell of the AuNPs. From subsequent structural analysis and electrical measurements, we could observe a successful molecular functionalization in nanoMoED devices as well as we could deduce that differences in electrical properties between two different device types are related to the differences in the molecular functionalization process for the two different AuNPs synthesized in first step. The same devices yielded successful NO2 gas sensing. This opens the pathway for a simplified synthesis/fabrication of molecular electronic devices with application potential.
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| 25. |
- Shi, Liyang, et al.
(författare)
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“Smart” drug loaded nanoparticle delivery from a self-healing hydrogel enabled by dynamic magnesium–biopolymer chemistry
- 2016
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Ingår i: Chemical Communications. - 1359-7345 .- 1364-548X. ; 52:74, s. 11151-11154
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Tidskriftsartikel (refereegranskat)abstract
- We report a strategy to generate a self-healing and pH responsive hydrogel network between drug-loaded nanoparticles and natural polysaccharides via magnesium–bisphosphonate ligand interactions. The injectable drug depot disassembles in a tumor-specific environment, providing localized uptake of the nanoparticles, which is highly appreciated in drug delivery applications and manufacturing of drug-loaded biomaterials using a syringe-based deposition technique.
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| 26. |
- Tian, Bo, et al.
(författare)
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MicroRNA Detection through DNAzyme-Mediated Disintegration of Magnetic Nanoparticle Assemblies
- 2018
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Ingår i: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 3, s. 1884-1891
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Tidskriftsartikel (refereegranskat)abstract
- DNA-assembled nanoparticle superstructures offer numerous bioresponsive properties that can be utilized for point-of-care diagnostics. Functional DNA sequences such as deoxyribozymes (DNAzymes) provide novel bioresponsive strategies and further extend the application of DNA-assembled nanoparticle superstructures. In this work, we describe a microRNA detection biosensor that combines magnetic nanoparticle (MNP) assemblies with DNAzyme-assisted target recycling. The DNA scaffolds of the MNP assemblies contain substrate sequences for DNAzyme and can form cleavage catalytic structures in the presence of target DNA or RNA sequences, leading to rupture of the scaffolds and disintegration of the MNP assemblies. The target sequences are preserved during the cleavage reaction and release into the suspension to trigger the digestion of multiple DNA scaffolds. The high local concentration of substrate sequences in the MNP assemblies reduces the diffusion time for target recycling. The concentration of released MNPs, which is proportional to the concentration of the target, can be quantified by a 405 nm laser-based optomagnetic sensor. For the detection of let-7b in 10% serum, after 1 h of isothermal reaction at 50 degrees C, we found a linear detection range between 10 pM and 100 nM with a limit of detection of 6 pM. For the quantification of DNA target in buffer solution, a limit of detection of 1.5 pM was achieved. Compared to protein enzyme-based microRNA detection methods, the proposed DNAzyme-based biosensor has an increased stability, a reduced cost and a possibility to be used in living cells, all of which are valuable features for biosensing applications.
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| 27. |
- Wang, JunXin, et al.
(författare)
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Extraction of Backscattering and Absorption Coefficients of Magnetite Nanosphere Composites from Light-Scattering Measurements : Implications for Optomagnetic Sensing
- 2020
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 3, s. 11172-11183
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Tidskriftsartikel (refereegranskat)abstract
- Interaction of light with magnetic nanoparticles, dispersed insolution or embedded in other materials, is of major interest in a range of applications, one example being optomagnetic sensors. In applied research, light absorption and scattering of nanoparticle composites are often quantified by the Kubelka−Munk two-flux radiative transfer model. In this paper, we synthesized magnetite (Fe3O4) nanospheres with different diameters and encapsulated them into a polymer matrix. Their spectral transmittance and reflectance were investigated by spectrophotometry, together with measurements of angle-resolved scattering in the forward and backward hemispheres. The measured angular distribution was applied to approximate the scattering-phase function inside the film, which could be well described by the revised Reynolds−McCormick model. The backscattering and absorption coefficients were derived by inversion of the Kubelka−Munk relations, using the interface reflectances obtained from angle-dependent measurements. We present detailed optical properties for samples with various particle concentrations and scattering layer thicknesses, consisting of the magnetite and polymer composites. The absorption and backscattering coefficients for particles of diameter 458 nm showed qualitative agreement with single-scattering Mie calculations. The optical properties of composites with smaller particles might beinfluenced by an oxidized Fe2O3-like surface layer. The present approach can be used to study different kinds of magnetic nanoparticle clusters, dispersed in a supporting medium, and thus provide optical parameters of relevance for interpreting results ofoptomagnetic sensing experiments.
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| 28. |
- Wang, Lin, et al.
(författare)
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Highly Enhanced Luminescence from Single-Crystalline C60·1m-xylene Nanorods
- 2006
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 18:17, s. 4190-4194
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Tidskriftsartikel (refereegranskat)abstract
- Single-crystalline C60â1m-xylene nanorods with a hexagonal structure were successfully synthesizedby evaporating a C60 solution in m-xylene at room temperature. The ratio of the length to the diameterof the nanorods can be controlled in the range of 10 to over 1000 for different applications. Thephotoluminescence (PL) intensity of the nanorods is about 2 orders of magnitude higher than that forpristine C60 crystals in air. Both UV and Raman results indicate that there is no charge transfer betweenC60 and m-xylene. It was found that the interaction between C60 and m-xylene molecules is of the vander Waals type. This interaction reduces the icosahedral symmetry of C60 molecule and induces strongPL from the solvate nanorods.
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| 29. |
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| 30. |
- Yang, Jiaojiao, et al.
(författare)
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Synthesis and Characterization of Amorphous Magnesium Carbonate Nanoparticles
- 2019
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Ingår i: Materials Chemistry and Physics. - : Elsevier. - 0254-0584 .- 1879-3312. ; 224, s. 301-307
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Tidskriftsartikel (refereegranskat)abstract
- We report the template-free, low-temperature, environment-friendly synthesis of amorphous magnesium carbonate nanoparticles (AMN). Scanning electron microscopy and transmission electron microscopy show that AMN consist of small nanoparticles approximately 20-65 nm in diameter. Drying temperature and centrifugation are shown to affect the nanostructure and functional properties of the material. Aggregated AMN can be produced with a total pore volume up to 1.72 cm(3)/g and can absorb as much as 24 mmol/g water, substantially surpassing the pore volume and moisture-absorbing capacity of all previously described alkali earth metal carbonates. The nanoparticles are foreseen to be useful in applications such as water sorption, drug delivery and catalysis.
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