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Luo, Jun
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Publications (10 of 18) Show all publications
Yang, J., Han, Y., Luo, J., Liefer, K., Strömme, M. & Welch, K. (2019). Synthesis and Characterization of Amorphous Magnesium Carbonate Nanoparticles. Materials Chemistry and Physics, 224, 301-307
Open this publication in new window or tab >>Synthesis and Characterization of Amorphous Magnesium Carbonate Nanoparticles
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2019 (English)In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 224, p. 301-307Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Nanoparticle, Amorphous, Magnesium carbonate, Water sorption
National Category
Nano Technology
Identifiers
urn:nbn:se:uu:diva-354505 (URN)10.1016/j.matchemphys.2018.12.037 (DOI)000456750900036 ()
Funder
VINNOVA
Available from: 2018-06-20 Created: 2018-06-20 Last updated: 2019-04-24Bibliographically approved
Luo, J., Faivre, J., Engqvist, H. & Persson, C. (2019). The Addition of Poly(Vinyl Alcohol) Fibers to Apatitic Calcium Phosphate Cement Can Improve Its Toughness. Materials, 12(9), Article ID 1531.
Open this publication in new window or tab >>The Addition of Poly(Vinyl Alcohol) Fibers to Apatitic Calcium Phosphate Cement Can Improve Its Toughness
2019 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 9, article id 1531Article in journal (Refereed) Published
Abstract [en]

Calcium phosphate cements, and in particular hydroxyapatite cements, have been widely investigated for use as bone void fillers due to their chemical similarity to bone and related osteoconductivity. However, they are brittle, which limits their use to non-load-bearing applications. The aim of the current study was to improve the toughness of hydroxyapatite cements through fiber reinforcement. The effect of the addition of hydrophilic, poly(vinyl-alcohol) (PVA) fibers to hydroxyapatite cement was evaluated in terms of mechanical properties, including compressive strength, diametral tensile strength and toughness (work of fracture), as well as setting time, phase composition and cement morphology. The fiber reinforcement enhanced the fracture resistance of the hydroxyapatite cement, but also simultaneously reduced the compressive strength and setting time of the cements. However, cement with 5 wt % of fibers (of the powder component) could be considered a good compromise, with a compressive strength of 46.5 +/- 4.6 MPa (compared to 62.3 +/- 12.8 MPa of that without fibers), i.e., still much greater than that of human trabecular bone (0.1-14 MPa). A significantly higher diametral tensile strength (9.2 +/- 0.4 MPa) was found for this cement compared to that without fibers (7.4 +/- 1.5 MPa). The work of fracture increased four times to 9.1 +/- 1.5 kJ/m(2) in comparison to the pristine apatite. In summary, the hydroxyapatite cements could be reinforced by suitable amounts of PVA fibers, which resulted in enhancing the material's structural integrity and ductility, and increased the material's resistance to cracking.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
fiber reinforcement, apatite cement, poly(vinyl alcohol), composite, compressive strength, work of fracture, diametral tensile strength, toughness
National Category
Ceramics
Identifiers
urn:nbn:se:uu:diva-387969 (URN)10.3390/ma12091531 (DOI)000469757500172 ()31083315 (PubMedID)
Available from: 2019-06-27 Created: 2019-06-27 Last updated: 2019-06-27Bibliographically approved
Luo, J., Engqvist, H. & Persson, C. (2018). A ready-to-use acidic, brushite-forming calcium phosphate cement. Acta Biomaterialia, 81, 304-314
Open this publication in new window or tab >>A ready-to-use acidic, brushite-forming calcium phosphate cement
2018 (English)In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 81, p. 304-314Article in journal (Refereed) Published
Abstract [en]

Premixed calcium phosphate cements have been developed to simplify the usage of traditional calcium phosphate cements and reduce the influence of the setting reaction on the delivery process. However, difficulties in achieving a good cohesion, adequate shelf life and sufficient mechanical properties have so far impeded their use in clinical applications, especially for the more degradable acidic calcium phosphate cements. In this study, a brushite cement was developed from a series of ready-to-use calcium phosphate pastes. The brushite cement paste was formed via mixing of a monocalcium phosphate monohydrate (MCPM) paste and a beta-tricalcium phosphate (beta-TCP) paste with good injectability and adequate shelf life. The MCPM paste was based on a water-immiscible liquid with two surfactants and the beta-Tcp paste on a sodium hyaluronate aqueous solution. The effect of citric acid as a retardant was assessed. Formulations with suitable amounts of citric acid showed good cohesion and mechanical performance with potential for future clinical applications. Statement of Significance Acidic calcium phosphate cements have attracted extensive attention as bone substitute materials due to their ability to resorb faster than basic calcium phosphate cements in vivo. However, traditionally, short working times and low mechanical strength have limited their clinical application. Premixed cements could simplify the clinical use as well as improve property reproducibility, but short shelf lives, low cohesion and low mechanical properties have restricted the development. In this study, an injectable ready-to-use two-phase system consisting of an MCPM paste and a beta-TCP paste was developed based on acidic cement. It shows good cohesion, compressive strength and adequate shelf life, which has the potential to be used in a dual chamber system for simplified and fast filling of bone defects in a minimally invasive manner. This will reduce surgery time, decrease the risk of contamination and ensure repeatable results.

Keywords
Ready-to-use, Acidic calcium phosphate cement, Brushite, Cohesion, Injectability, Shelf life
National Category
Ceramics
Identifiers
urn:nbn:se:uu:diva-372719 (URN)10.1016/j.actbio.2018.10.001 (DOI)000451937500024 ()30291976 (PubMedID)
Funder
Swedish Foundation for Strategic Research
Available from: 2019-01-08 Created: 2019-01-08 Last updated: 2019-01-08Bibliographically approved
Luo, J. (2018). Calcium Phosphate Based Biomaterials for Bone Augmentation. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Calcium Phosphate Based Biomaterials for Bone Augmentation
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Basic (apatite-based) calcium phosphate cements (CPCs), and acidic (brushite and monetite-based) CPCs are used as bone replacement materials because of their bioactivity, mouldability and ability to harden in place. However, their application is limited by their inherent brittleness and difficulties related to their handling. The current thesis aimed to provide solutions to these limitations.

To assess the baseline, the mechanical properties of two promising experimental and two commercially available apatite and brushite cements were investigated. The two experimental CPCs exhibited significantly higher mechanical strengths than the two commercially available ones, warranting further advancement of the former towards clinical use.

The setting reaction of brushite cements was, for the first time, quantitatively studied in the first seconds and minutes, using synchrotron X-ray diffraction. The reaction was found to include a fast nucleation induction period (<9 s), nucleation (<18 s), brushite content increase and setting completion. The effect of the commonly used retardant citric acid – which usually also gives stronger brushite cements - was also evaluated, providing important information for further cement development.  

To overcome complicated usage and short shelf life of acidic CPCs, a ready-to-use acidic CPC was developed by mixing a monocalcium phosphate monohydrate (MCPM) paste and a β-tricalcium phosphate (β-TCP) paste with suitable amounts of citric acid. The CPC showed adequate shelf life, good cohesion and mechanical performance.

To mitigate against the brittle behavior of CPCs, i) poly(vinyl alcohol) fibres were used to reinforce apatite cements, significantly improving the apatite matrix’s toughness and resistance to cracking; ii) injectable, ready-to-use organic-inorganic composites with partly elastomeric compression behavior were designed based on silk fibroin hydrogels and acidic calcium phosphates, and their ability for antibiotic drug delivery was assessed. 

In summary, insights into the functional properties of currently available CPCs as well as the setting process of brushite cements were gained and several new calcium phosphate-based formulations were developed to overcome some of the drawbacks of traditional CPCs. Further studies, in particular of the biological response, are needed to verify the potential of the developed materials for future use in the clinical setting. 

 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 55
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1700
Keywords
bone substitute materials, calcium phosphate cements, apatite, brushite, monetite, setting mechanism, premixed, fibre reinforcement, composite, silk fibroin, mechanical properties
National Category
Ceramics Composite Science and Engineering
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-356982 (URN)978-91-513-0399-4 (ISBN)
Public defence
2018-09-28, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2018-09-05 Created: 2018-08-10 Last updated: 2018-09-10
Chen, S., Shi, L., Luo, J. & Engqvist, H. (2018). Novel Fast-Setting Mineral Trioxide Aggregate: Its Formulation, Chemical-Physical Properties, and Cytocompatibility. ACS Applied Materials and Interfaces, 10(24), 20334-20341
Open this publication in new window or tab >>Novel Fast-Setting Mineral Trioxide Aggregate: Its Formulation, Chemical-Physical Properties, and Cytocompatibility
2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 24, p. 20334-20341Article in journal (Refereed) Published
Abstract [en]

One of the main drawbacks that limits the application of mineral trioxide aggregate (MTA) in dental field is its long setting time. Mineral trioxide aggregate with accelerated setting properties and excellent chemical-physical and biological properties is still required. In this study, an innovative mineral trioxide aggregate, which consists of calcium silicates, calcium aluminates, and zirconium oxide, was designed to obtain fast-setting property. The optimized formulation can achieve initial setting in 10 min and final setting in 15 min, which are much faster than commercial mineral trioxide aggregate. In addition, the optimized fast-setting MTA showed adequate radiopacity and good biocompatibility. The ion concentrations after storage in water for 1 day were 52.3 mg/L Ca, 67.7 mg/L Al, 48.8 mg/L Si, and 11.7 mg/L Mg. The hydration products of hardened cements were investigated by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared, showing the accelerated setting time was due to the formation of honeycomb-like calcium silicate hydrate gel. The novel MTA could be a promising material for dental applications.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
Keywords
mineral trioxide aggregate, dental cements, fast setting, calcium silicates, calcium aluminates
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-358684 (URN)10.1021/acsami.8b04946 (DOI)000436211500015 ()29873476 (PubMedID)
Available from: 2018-09-05 Created: 2018-09-05 Last updated: 2018-09-06Bibliographically approved
Luo, J., Martinez-Casado, F. J., Balmes, O., Yang, J., Persson, C., Engqvist, H. & Xia, W. (2017). In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth. ACS Applied Materials and Interfaces, 9(41), 36392-36399
Open this publication in new window or tab >>In-situ Synchrotron X-ray Diffraction Analysis of the Setting Process of Brushite Cement: Reaction and Crystal Growth
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2017 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 41, p. 36392-36399Article in journal (Refereed) Published
Abstract [en]

Brushite cements are fast self-setting materials that can be used as bone substitute materials. Although tracing their fast setting process is a challenge, it is important for the understanding of the same, which in turn is important for the material’s further development and use in the clinics. In this study, the setting rate, phase formation, and crystal growth of brushite cements were quantitatively studied by in situ synchrotron powder X-ray diffraction (SXRD) on a time scale of seconds. The influence of reactant ratios and a retardant (citric acid) on the setting reaction were analyzed. To complement the in situ investigations, scanning electron microscopy was carried out for ex situ morphological evolution of crystals. The initial reaction followed a four-step process, including a fast nucleation induction period, nucleation, crystal growth, and completion of the setting. The brushite crystal size grew up to the micro scale within 1 min, and the brushite content increased linearly after the nucleation until all monocalcium phosphate monohydrate (MCPM; Ca(H2PO4)2·H2O) had dissolved within minutes, followed by a slow increase until the end of the monitoring. By adjusting the MCPM to the β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) ratio in the starting powders, the brushite/monetite ratio in the cements could be modified. In the presence of citric acid, the formation of brushite nuclei was not significantly retarded, whereas the increase in brushite content and the growth of crystal size were effectively hindered. The amount of monetite also increased by adding citric acid. This is the first time that the brushite setting process has been characterized in the first seconds and minutes of the reaction by SXRD.

Keywords
synchrotron X-ray diffraction, setting reaction process, brushite cement, crystal size, citric acid, MCPM/β-TCP ratio
National Category
Engineering and Technology Medical Materials Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-330146 (URN)10.1021/acsami.7b10159 (DOI)000413503700092 ()
Available from: 2017-09-26 Created: 2017-09-26 Last updated: 2018-08-10Bibliographically approved
Luo, J., Ajaxon, I., Ginebra, M. P., Engqvist, H. & Persson, C. (2016). Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements. Journal of The Mechanical Behavior of Biomedical Materials, 60, 617-627
Open this publication in new window or tab >>Compressive, diametral tensile and biaxial flexural strength of cutting-edge calcium phosphate cements
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2016 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 60, p. 617-627Article in journal (Refereed) Published
Abstract [en]

Calcium phosphate cements (CPCs) are widely used in bone repair. Currently there are two main types of CPCs, brushite and apatite. The aim of this project was to evaluate the mechanical properties of particularly promising experimental brushite and apatite formulations in comparison to commercially available brushite- and apatite-based cements (chronOS Inject and Norian® SRS®, respectively), and in particular evaluate the diametral tensile strength and biaxial flexural strength of these cements in both wet and dry conditions for the first time. The cements׳ porosity and their compressive, diametral tensile and biaxial flexural strength were tested in wet (or moist) and dry conditions. The surface morphology was characterized by scanning electron microscopy. Phase composition was assessed with X-ray diffraction. It was found that the novel experimental cements showed better mechanical properties than the commercially available cements, in all loading scenarios. The highest compressive strength (57.2±6.5 MPa before drying and 69.5±6.0 MPa after drying) was found for the experimental brushite cement. This cement also showed the highest wet diametral tensile strength (10.0±0.8 MPa) and wet biaxial flexural strength (30.7±1.8 MPa). It was also the cement that presented the lowest porosity (approx. 12%). The influence of water content was found to depend on cement type, with some cements showing higher mechanical properties after drying and some no difference after drying.

Keywords
Calcium phosphate cement; Brushite; Apatite; Compressive strength; Tensile strength; Flexural strength
National Category
Ceramics
Identifiers
urn:nbn:se:uu:diva-284218 (URN)10.1016/j.jmbbm.2016.03.028 (DOI)000378969100055 ()27082025 (PubMedID)
Funder
The Swedish Foundation for International Cooperation in Research and Higher Education (STINT), IG2011-2047Swedish Research Council, 621-2011-6258
Available from: 2016-04-15 Created: 2016-04-15 Last updated: 2018-08-10Bibliographically approved
Rosental, A., Tarre, A., Gerst, A., Kasikov, A., Lu, J., Ottosson, M. & Uustare, T. (2013). Epitaxial Single and Double Nanolayers of SnO2 and TiO2 for Resistive Gas Sensors. IEEE Sensors Journal, 13(5), 1648-1655
Open this publication in new window or tab >>Epitaxial Single and Double Nanolayers of SnO2 and TiO2 for Resistive Gas Sensors
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2013 (English)In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 5, p. 1648-1655Article in journal (Refereed) Published
Abstract [en]

Rutile TiO2 (1 0 1) and cassiterite SnO2 (1 0 1) epitaxial single and double nanolayers, the latter stacked in either sequence, are atomic layer deposited on r-cut alpha-Al2O3(0 1 (1) over bar 2) substrates. Thickness of the layers is varied. Epitaxial quality of the films is characterized by X-ray diffraction (XRD), reflection high-energy electron diffraction, and transmission electron microscopy. In gas response measurements, as-grown films and the films coated with electron-beam evaporated Pt nanoclusters are exposed, at 350 degrees C, to H-2, CO, and CH4 diluted in air. In response to test gas concentrations of 30 parts per million (ppm), the films with a thickness of order of 10 nm exhibit, depending on the makeup and gas, as high as two- to five-fold decrease in the resistance. It is shown that the platinum surface catalyst is effective in accelerating the response and recovery processes. The transition times of the order of a few tens of seconds are observed. The results demonstrate the feasibility of gas sensing with single-crystal-like nanolayer films. Comparison of sensor characteristics of such quasi-2D nanostructures and the literature data relevant to individual nanowires, nanorods, and nanobelts, i.e., typical representatives of the quasi-1D structures, shows that, as to H-2, CO, and CH4, both structures are worthy competitors.

Keywords
Atomic layer deposition (ALD), epitaxy, nanostructuring, thin film sensors
National Category
Natural Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-200048 (URN)10.1109/JSEN.2013.2238227 (DOI)000317486700001 ()
Available from: 2013-05-23 Created: 2013-05-20 Last updated: 2017-12-06Bibliographically approved
Luo, J., Qiu, Z., Deng, J., Zhao, C., Li, J., Wang, W., . . . Zhang, S.-L. (2013). Variation of Schottky barrier height induced by dopant segregation monitored by contact resistivity measurements. In: : . Paper presented at 17th European Workshop on Materials for Advanced Metallization 2013 (MAM’2013), Leuven, Belgium, March 11-13, 2013..
Open this publication in new window or tab >>Variation of Schottky barrier height induced by dopant segregation monitored by contact resistivity measurements
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2013 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-213587 (URN)
Conference
17th European Workshop on Materials for Advanced Metallization 2013 (MAM’2013), Leuven, Belgium, March 11-13, 2013.
Available from: 2013-12-29 Created: 2013-12-29 Last updated: 2016-04-21
Kukli, K., Aarik, J., Aidla, A., Jogi, I., Arroval, T., Lu, J., . . . Thompson, D. M. (2012). Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen. Thin Solid Films, 520(7), 2756-2763
Open this publication in new window or tab >>Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen
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2012 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, no 7, p. 2756-2763Article in journal (Refereed) Published
Abstract [en]

Ru thin films were grown on hydrogen terminated Si, SiO2, Al2O3, HfO2, and TiO2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4-20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250-255 degrees C, the growth of the Ru films was favored on silicon, compared to the growth on Al2O3, TiO2 and HfO2. At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO2, compared to the process on silicon. At 320-325 degrees C, no growth occurred on Si-H and SiO2-covered silicon. Resistivity values down to 18 mu Omega.cm were obtained for ca. 10 nm thick Ru films. 

Keywords
Atomic layer deposition, Metal films, Ruthenium
National Category
Materials Engineering
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-174604 (URN)10.1016/j.tsf.2011.11.088 (DOI)000301085100064 ()
Available from: 2012-05-24 Created: 2012-05-22 Last updated: 2017-12-07Bibliographically approved
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