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Qin, T., Qin, W., Ma, M., Zhang, D., Hu, S., Zhang, P., . . . Engqvist, H. (2018). A novel rapid synthesis, characterization and applications of calcium phosphate nanospheres from Baltic seawater. Ceramics International, 44(8), 9076-9079
Open this publication in new window or tab >>A novel rapid synthesis, characterization and applications of calcium phosphate nanospheres from Baltic seawater
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2018 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 44, no 8, p. 9076-9079Article in journal (Refereed) Published
Abstract [en]

Due to the considerable high bio-compatibility, calcium phosphate nanoparticles are widely used in biomedical applications. This study proposes a novel strategy for low-cost manufacturing calcium phosphate nanoporous spheres. The controlled reaction only took less than five minutes, when using Baltic seawater with the dissolved calcium concentration of 2.2 mM as the calcium resources. Porous nanospheres were obtained, with spheres ranging from 50 to 130 nm. The obtained nanospheres possess high drug-loading capacity and exhibit sustained release and pH-dependent properties. In addition, this method provides a general efficient strategy to synthesize other low-cost inorganic nanospheres from seawater.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2018
Keywords
Seawater, Nanosphere, Low cost, Drug, Calcium phosphate
National Category
Materials Chemistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-356619 (URN)10.1016/j.ceramint.2018.02.114 (DOI)000430522200044 ()
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2018-08-23Bibliographically approved
Qin, T., Qin, W., Ma, M., Zhang, D., Hu, S., Zhang, P., . . . Engqvist, H. (2018). A novel rapid synthesis, characterization and applications of calcium phosphate nanspheres from Baltic seawater. Ceramics International
Open this publication in new window or tab >>A novel rapid synthesis, characterization and applications of calcium phosphate nanspheres from Baltic seawater
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2018 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956Article in journal (Refereed) In press
Abstract [en]

Due to the considerable high bio-compatibility, calcium phosphate nanoparticles are widely used in biomedicalapplications. This study proposes a novel strategy for low-cost manufacturing calcium phosphate nanoporousspheres. The controlled reaction only took less than five minutes, when using Baltic seawater with the dissolvedcalcium concentration of 2.2 mM as the calcium resources. Porous nanospheres were obtained, with spheresranging from 50 to 130 nm. The obtained nanospheres possess high drug-loading capacity and exhibit sustainedrelease and pH-dependent properties. In addition, this method provides a general efficient strategy to synthesizeother low-cost inorganic nanospheres from seawater.

National Category
Ceramics
Identifiers
urn:nbn:se:uu:diva-350780 (URN)
Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-06-04Bibliographically approved
Mellgren, T., Qin, T., Öhman Mägi, C., Zhang, Y., Wu, B., Xia, W. & Engqvist, H. (2018). Calcium Phosphate Microspheres as a Delivery Vehicle for Tooth-Bleaching Agents. Journal of Dental Research, 97(3), 283-288
Open this publication in new window or tab >>Calcium Phosphate Microspheres as a Delivery Vehicle for Tooth-Bleaching Agents
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2018 (English)In: Journal of Dental Research, ISSN 0022-0345, E-ISSN 1544-0591, Vol. 97, no 3, p. 283-288Article in journal (Refereed) Published
Abstract [en]

Bleaching of vital teeth has become common practice in cosmetic dentistry today. Tooth sensitivity and demineralization of the enamel are, however, common side effects associated with hydrogen and carbamide peroxide bleaching. This study investigated if calcium phosphate microspheres, which have remineralizing properties, could be used as an additive without hindering the diffusion of the bleaching agent and if the spheres could be used as a carrier for carbamide peroxide. A remineralizing agent could increase the safety of bleaching and decrease the severity of its side effects. Comparisons between current hydrogen peroxide diffusion studies and previously published work are difficult since many studies include challenging-to-replicate conditions or lack reporting of important parameters. Hence, a diffusion model was designed by Wu Lab (School of Dentistry, University of California, Los Angeles) to measure the diffusion flux and determine the diffusivity of hydrogen peroxide. Physical parameters (e.g., diffusivity) could then be used for direct comparison to the results obtained by future studies. Three whitening gels with increasing amounts of spheres were formulated and tested with 2 commercially available whitening gels. The flux of hydrogen peroxide through 1-mm discs of bovine enamel was measured at steady-state conditions, and the diffusivity was calculated. The results showed that the spheres could be used as a carrier for carbamide peroxide and that the amount of spheres did not affect the diffusivity of peroxide through the enamel discs. Hence, the microspheres are considered promising as an additive to minimize side effects in bleaching gel formulation.

Place, publisher, year, edition, pages
SAGE PUBLICATIONS INC, 2018
Keywords
dental enamel, diffusion, peroxide, tooth whitening, tooth sensitivity, tooth remineralization
National Category
Dentistry Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-352988 (URN)10.1177/0022034517741295 (DOI)000429319800006 ()29125909 (PubMedID)
Funder
Swedish Research Council, 20135419
Available from: 2018-07-17 Created: 2018-07-17 Last updated: 2018-07-25Bibliographically approved
Janson, O., Strømme, M., Engqvist, H. & Welch, K. (2018). Debridement of Bacterial Biofilms with TiO2/H2O2 Solutions and Visible Light Irradiation. International Journal of Biomaterials, 2018, 1-8, Article ID 5361632.
Open this publication in new window or tab >>Debridement of Bacterial Biofilms with TiO2/H2O2 Solutions and Visible Light Irradiation
2018 (English)In: International Journal of Biomaterials, Vol. 2018, p. 1-8, article id 5361632Article in journal (Refereed) Published
Abstract [en]

Objectives. The aim of the study was to explore the debridement efficacy of different solutions of H2O2 and rutile particles against Staphylococcus epidermidis and Pseudomonas aeruginosa biofilms attached to titanium surfaces when exposed to visible light. Materials and Methods. Titanium discs cultivated with biofilms of Staphylococcus epidermidis or Pseudomonas aeruginosa were subjected for 1 min to suspensions consisting of rutile particles mixed with high (950 mM) or low (2 mM) concentrations of H2O2 under visible light irradiation (405 nm; 2.1 mW/cm2). Discs were rinsed and the degree of debridement was determined through scanning electron microscopy and viability assessment of the remaining bacteria using luminescence measurements and/or a metabolic activity assay. Results. Cleaning mixtures containing the higher concentration of H2O2 showed a significantly improved debridement compared to the negative control in all experiments. The addition of rutile particles was shown to have a statistically significant effect in one test with S. epidermidis. Limited evidence of the catalytic effect of visible light irradiation was seen, but effects were relatively small and statistically insignificant. Conclusions. H2O2 at a concentration of 950 mM proved to be the strongest contribution to the debridement and bactericidal effect of the cleaning techniques tested in this study.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2018
National Category
Nano Technology
Research subject
Engineering Science with specialization in Nanotechnology and Functional Materials; Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-355674 (URN)10.1155/2018/5361632 (DOI)
Available from: 2018-07-03 Created: 2018-07-03 Last updated: 2018-08-28
Sladkova, M., Pujari-Palmer, M., Öhman, C., Cheng, J., Al-Ansari, S., Saad, M., . . . de Peppo, G. M. (2018). Engineering human bone grafts with new macroporous calcium phosphate cement scaffolds. Journal of Tissue Engineering and Regenerative Medicine, 12(3), 715-726
Open this publication in new window or tab >>Engineering human bone grafts with new macroporous calcium phosphate cement scaffolds
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2018 (English)In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, E-ISSN 1932-7005, Vol. 12, no 3, p. 715-726Article in journal (Refereed) Published
Abstract [en]

Bone engineering opens the possibility to grow large amounts of tissue products by combining patient-specific cells with compliant biomaterials. Decellularized tissue matrices represent suitable biomaterials, but availability, long processing time, excessive cost, and concerns on pathogen transmission have led to the development of biomimetic synthetic alternatives. We recently fabricated calcium phosphate cement (CPC) scaffolds with variable macroporosity using a facile synthesis method with minimal manufacturing steps and demonstrated long-term biocompatibility in vitro. However, there is no knowledge on the potential use of these scaffolds for bone engineering and whether the porosity of the scaffolds affects osteogenic differentiation and tissue formation in vitro. In this study, we explored the bone engineering potential of CPC scaffolds with two different macroporosities using human mesenchymal progenitors derived from induced pluripotent stem cells (iPSC-MP) or isolated from bone marrow (BMSC). Biomimetic decellularized bone scaffolds were used as reference material in all experiments. The results demonstrate that, irrespective of their macroporosity, the CPC scaffolds tested in this study support attachment, viability, and growth of iPSC-MP and BMSC cells similarly to decellularized bone. Importantly, the tested materials sustained differentiation of the cells as evidenced by increased expression of osteogenic markers and formation of a mineralized tissue. In conclusion, the results of this study suggest that the CPC scaffolds fabricated using our method are suitable to engineer bone grafts from different cell sources and could lead to the development of safe and more affordable tissue grafts for reconstructive dentistry and orthopaedics and in vitro models for basic and applied research.

National Category
Other Medical Engineering
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-335996 (URN)10.1002/term.2491 (DOI)000427137100061 ()28635177 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2018-06-04Bibliographically approved
Pujari-Palmer, M., Robo, C., Persson, C., Procter, P. & Engqvist, H. (2018). Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out. Journal of The Mechanical Behavior of Biomedical Materials, 77, 624-633
Open this publication in new window or tab >>Influence of cement compressive strength and porosity on augmentation performance in a model of orthopedic screw pull-out
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2018 (English)In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 77, p. 624-633Article in journal (Refereed) Published
Abstract [en]

Disease and injuries that affect the skeletal system may require surgical intervention and internal fixation, i.e. orthopedic plate and screw insertion, to stabilize the injury and facilitate tissue repair. If the surrounding bone quality is poor the screws may migrate, or the bone may fail, resulting in screw pull-out. Though numerous studies have shown that cement augmentation of the interface between bone and implant can increase screw holding strength in bone, the physical properties of cement that influence pull-out force have not been investigated. The present study sought to determine how the physical properties of calcium phosphate cements (CPCs), and the strength of the biological or synthetic material surrounding the augmented screw, affected the corresponding orthopedic screw pull-out force in urethane foam models of healthy and osteoporotic bone (Sawbones). In the simplest model, where only the bond strength between screw thread and cement (without Sawbone) was tested, the correlation between pull-out force and cement compressive strength (R2 = 0.79) was weaker than correlation with total cement porosity (R2 = 0.89). In open pore Sawbone that mimics “healthy” cancellous bone density the stronger cements produced higher pull-out force (50-60% increase). Higher strength, lower porosity, cements also produced higher pull-out forces (50-190% increase) in Sawbones with cortical fixation if the failure strength of the cortical material was similar to (bovine tibial bone), or greater than (metal shell), actual cortical bone. This result is of particular clinical relevance where fixation with a metal plate implant is indicated, as the nearby metal can simulate a thicker cortical shell and, thereby, increase the pull-out force of screws augmented with stronger cements. The improvement in pull-out force was apparent even at low augmentation volumes of 0.5 ml (50% increase), which suggest that in clinical situations where augmentation volume is limited the stronger, lower porosity CPCs may still produce a significant improvement in screw holding strength. When correlations of all the tested models were compared both cement porosity and compressive strength accurately predicted pull-out force (R2=1.00, R2=0.808), though prediction accuracy depended upon the strength of the material surrounding the Sawbone. The correlations strength was low for bone with no, or weak, cortical fixation. Higher strength and lower porosity CPCs also produced greater pull-out force (1-1.5 kN) than commercial CPC (0.2-0.5kN), but lower pull-out force than PMMA (2-3 kN). The results of this study suggest that the likelihood of screw fixation failure may be reduced by selecting calcium phosphate cements with lower porosity and higher bulk strength, in patients with healthy bone mineral density and/or sufficient cortical thickness. This is of particular clinical relevance when fixation with metal plates is indicated, or where the augmentation volume is limited.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Screw pull-out, Orthopedic screw augmentation, Calcium phosphate cement, Bioceramic, Bone biomechanics, Sawbones, Cortical fixation
National Category
Medical Materials Ceramics Applied Mechanics Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-320157 (URN)10.1016/j.jmbbm.2017.10.016 (DOI)000418309500073 ()29100205 (PubMedID)
Funder
Swedish Research Council, 621–2011-3399EU, FP7, Seventh Framework Programme, 262948
Available from: 2017-04-16 Created: 2017-04-16 Last updated: 2018-02-16Bibliographically approved
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
Qin, T., Ma, M., Qin, W., Xiao, X., Nikolajeff, F. & Engqvist, H. (2018). Rapid precipitation of Mg-doped fluoride-based submicron spheres and evolution study. Journal of Solid State Chemistry (260), 142-146
Open this publication in new window or tab >>Rapid precipitation of Mg-doped fluoride-based submicron spheres and evolution study
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2018 (English)In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, no 260, p. 142-146Article in journal (Refereed) Published
National Category
Signal Processing
Identifiers
urn:nbn:se:uu:diva-350781 (URN)000428005000021 ()
Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2018-06-04Bibliographically approved
Fu, L., Engqvist, H. & Xia, W. (2018). Spark plasma sintering of biodegradable Si3N4 bioceramic with Sr, Mg and Si as sintering additives for spinal fusion. Journal of the European Ceramic Society, 38(4), 2110-2119
Open this publication in new window or tab >>Spark plasma sintering of biodegradable Si3N4 bioceramic with Sr, Mg and Si as sintering additives for spinal fusion
2018 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 38, no 4, p. 2110-2119Article in journal (Refereed) Published
Abstract [en]

Silicon nitride (Si3N4) bioceramics with standard sintering additives (Al2O3 and Y2O3) are used in spinal fusion. Alternative Si3N4 bioceramics with biologically beneficial sintering additives could lead to improved osseoin- tegrative properties. The aim of this study is to obtain dense and strong Si3N4 bioceramics by using SrO, MgO and SiO2 as sintering additives, and evaluate the effect of these sintering additives on microstructures and properties of Si3N4 bioceramics. Raw powders with 10 wt% and 18 wt% sintering additives were sintered by spark plasma sintering. Samples sintered at 1750 °C, with an applied pressure of 60 MPa and a holding time of 3 min, showed the highest content of β-Si3N4 (94.9%). The mechanical properties of the developed Si3N4 bio- ceramics are comparable to the mechanical properties of currently used structural Si3N4 ceramics sintered with standard sintering additives (Al2O3 and Y2O3). The highest flexural strength of the developed Si3N4 bioceramics reached 1079 MPa. Ion release results showed that Sr2+,Mg2+ and Si4+ ions kept leaching out within 10 days’ immersion. The degradable Si3N4 bioceramics with adequate strength and biologically beneficial sintering ad- ditives show the promise for load bearing biomedical applications, such as spinal fusion.

National Category
Natural Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-331879 (URN)10.1016/j.jeurceramsoc.2017.10.003 (DOI)000424716700136 ()
Funder
Carl Tryggers foundation
Available from: 2017-10-19 Created: 2017-10-19 Last updated: 2018-08-12Bibliographically approved
Persson, J., Helgason, B., Engqvist, H., Ferguson, S. & Persson, C. (2018). Stiffness and strength of cranioplastic implant systems in comparison to cranial bone. Journal of Cranio-Maxillofacial Surgery, 46(3), 418-423
Open this publication in new window or tab >>Stiffness and strength of cranioplastic implant systems in comparison to cranial bone
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2018 (English)In: Journal of Cranio-Maxillofacial Surgery, ISSN 1010-5182, E-ISSN 1878-4119, Vol. 46, no 3, p. 418-423Article in journal (Refereed) Published
Abstract [en]

Purpose: The aim of this study was to evaluate skull replacement options after decompressive craniectomy by systematically investigating which combination of geometrical properties and material selection would result in a mechanical response comparable in stiffness to that of native skull bone and a strength as high or higher than the same. Materials and methods: The study was conducted using a Finite Element Model of the top part of a human skull. Native skull bone, autografts and commercial implants made of PEEK, solid titanium, two titanium meshes and a titanium-ceramic composite were modeled under a set load to evaluate deformation and maximum stress. Results: The computational result showed a large variation of the strength and effective stiffness of the autografts and implants. The stiffness of native bone varied by a factor of 20 and the strength by a factor of eight. The implants span the entire span of the native skull, both in stiffness and strength. Conclusion: All the investigated implant materials had a potential for having the same effective stiffness as the native skull bone. All the materials also had the potential to be as strong as the native bone. To match inherent properties, the best choice of material and thickness is thus patient specific, depending on the quality of the patient's native bone.

Keywords
Craniectomy, Cranioplasty, OSSDSIGN cranial, Craniocurve, KLS martin mesh system, Mechanical properties
National Category
Medical Materials Biomaterials Science
Research subject
Engineering Science with specialization in Materials Science
Identifiers
urn:nbn:se:uu:diva-347586 (URN)10.1016/j.jcms.2017.11.025 (DOI)000425712500007 ()
Funder
EU, Horizon 2020, E!9741
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-26Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9529-650X

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