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- Atif, Abdul Raouf, 1996-, et al.
(författare)
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A Universal Microfluidic Platform for In Vitro Biomaterial Evaluation
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION: Conventionally, the biological properties of biomaterials are evaluated using well plates. Although being a standardized method, it is static in terms of fluid flow and is far from the physiological conditions found in vivo. This work presents a versatile microfluidic system that allows for integration of different biomaterials (ceramic, metals and polymers) under dynamic conditions.METHODS: The Universal Biomaterial-on-Chip (UBOC) consisted of two separate 3D printed (Polylactic acid, Ultimaker 2+) structures: the upper layer which contains the channel through which medium can flow (Fig1A) and the bottom layer that holds and secures the biomaterial in place (Fig 1B). A glass coverslip was taped to the upper layer to tightly seal the channel. Subsequently, an oval Polydimethylsiloxane (PDMS) gasket (l=10mm,w=7mm, h=0.8mm) was inserted into the periphery of the channel in the upper layer. Furthermore, magnets (Ø=12mm, h=3mm) were glued on both sides of the bottom layer. To close the channel, two magnets were placed on the upper layer, causing attraction to the magnets in the bottom layer. The gasket would then directly interface with the biomaterial inside the bottom layer, creating a leak-free channel on its surface. MC3T3-E1 pre-osteoblasts were seeded in the UBOC platform (50,000 cells/cm2) on calcium-deficient hydroxyapatite (HA) (Ø=15mm) and clinical grade titanium (Ti) (Ø=12mm). The cells were cultured for a period of 5 days at a flow rate of 2 μl/min using supplemented MEM-α medium (Hyclone, 10% FBS, 1% Pen-Strep). On day 5, the cells were stained on-chip with Live/Dead stain (Calcein, Propidium Iodide and Hoechst) and subsequently imaged.RESULTS: HA and Ti samples were successfully integrated into the UBOC. Cells cultured on-chip displayed a high degree of viability and confluence on day 5 of culture on both HA and Ti substrates (Fig 2).DISCUSSION & CONCLUSIONS: UBOC presents the possibility for flexible in vitro biomaterial analysis as it allows for easy incorporation of flow to conventional cell culture regimes in a low-cost manner. Via this method,cells can be cultured on the biomaterial with exposure to fluid flow and controlled shear-stress. The platform is compatible with standard characterization methods, such as imaging and biochemical cell analysis. In addition, since the system is designed to be opened and closed, the biomaterial could be easily accessed, harvested and transferred to a regular tissue culture vessel,enabling standard off-chip biochemical assays and protocols to be performed for further analysis.
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- Atif, Abdul-Raouf, 1996-, et al.
(författare)
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Experimental Characterization and Mathematical Modeling of the Adsorption of Proteins and Cells on Biomimetic Hydroxyapatite
- 2022
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:1, s. 908-920
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Tidskriftsartikel (refereegranskat)abstract
- Biomaterial development is a long process consisting of multiple stages of design and evaluation within the context of both in vitro and in vivo testing. To streamline this process, mathematical and computational modeling displays potential as a tool for rapid biomaterial characterization, enabling the prediction of optimal physicochemical parameters. In this work, a Langmuir isotherm-based model was used to describe protein and cell adhesion on a biomimetic hydroxyapatite surface, both independently and in a one-way coupled system. The results indicated that increased protein surface coverage leads to improved cell adhesion and spread, with maximal protein coverage occurring within 48 h. In addition, the Langmuir model displayed a good fit with the experimental data. Overall, computational modeling is an exciting avenue that may lead to savings in terms of time and cost during the biomaterial development process.
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- Ballo, Ahmed, 1978, et al.
(författare)
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Bone tissue reactions to biomimetic ion-substituted apatite surfaces on titanium implants
- 2012
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5689 .- 1742-5662. ; 9:72, s. 1615-1624
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the bone tissue response to strontium-and silicon-substituted apatite (Sr-HA and Si-HA) modified titanium (Ti) implants. Sr-HA, Si-HA and HA were grown on thermally oxidized Ti implants by a biomimetic process. Oxidized implants were used as controls. Surface properties, i.e. chemical composition, surface thickness, morphology/pore characteristics, crystal structure and roughness, were characterized with various analytical techniques. The implants were inserted in rat tibiae and block biopsies were prepared for histology, histomorphometry and scanning electron microscopy analysis. Histologically, new bone formed on all implant surfaces. The bone was deposited directly onto the Sr-HA and Si-HA implants without any intervening soft tissue. The statistical analysis showed significant higher amount of bone-implant contact (BIC) for the Si-doped HA modification (P = 0.030), whereas significant higher bone area (BA) for the Sr-doped HA modification (P = 0.034), when compared with the non-doped HA modification. The differences were most pronounced at the early time point. The healing time had a significant impact for both BA and BIC (P < 0.001). The present results show that biomimetically prepared Si-HA and Sr-HA on Ti implants provided bioactivity and promoted early bone formation.
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| 8. |
- Bang, Le T., et al.
(författare)
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Synthesis and assessment of metallic ion migration through a novel calcium carbonate coating for biomedical implants
- 2020
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 108:2, s. 429-438
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Tidskriftsartikel (refereegranskat)abstract
- Titanium (Ti) implants are commonly regarded as well accepted by the body. However, metal ion release is still a cause for concern. A small decrease in pH, which can be caused by inflammation, may produce a large increase in the corrosion rate of Ti implants. Coating the alloy with a buffer layer could have a significant protective effect. In this study, a calcium carbonate coating was developed on commercially pure Ti and a Ti-6Al-4V alloy through a hydrothermal treatment of previously NaOH-treated surfaces in calcium-citric acid chelate complexes. The results showed that a superstructured calcite coating layer formed on the Ti substrate after treatment at 170 degrees C for 3 hr. The coating was approx. 1 mu m thick and covered the substrate surface uniformly. When prolonging the hydrothermal treatment from 5 hr to 24 hr, the rhombohedral structure of calcite was observed in addition to the superstructure of calcite. Dissolution test results showed no significant differences in solution pH between the coated- and un-coated samples. However, the CaCO3 coating reduced by approx. 2-5 times the Ti and V ion release from the substrate as compared to the uncoated material, at pH 4. CaCO3 and hydroxyapatite (HA) coatings gave nonsignificant effects at neutral pH although the HA coating showed a trend for better results at the longer time points. The reduction in metal ion release from the substrate and the buffering ability of the CaCO3 coating encourage further studies on this coating for clinical applications.
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| 9. |
- Berg, Camilla, et al.
(författare)
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ACP-Mg particles for treatment of dental hypersensitivity : a mode of action study
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction/purpose:Dental hypersensitivity is a common clinical condition usually associated with exposed dentinal tubules. Occlusion of those, hindering fluid movement as a response to external stimuli, is one approach to reduce pain.[1] The occluding agent should induce mineralization and have a good filling effect. In this study, particles (200-400 nm) of Amorphous Calcium Phosphate with Mg (ACP-Mg) were used aiming to evaluate the mode of action with in-vitro studies on dentine as well as degradation properties in buffered systems.Methods:Degradation properties and ion-release was monitored by dispersing the particles in Tris-HCl (10 mg/mL) storing the dispersions at 37 °C. In-vitro testing was performed on 1 mm thick dentine discs cut from extracted human molars. Specimens were etched in 35 % phosphoric acid, rinsed with DI-water followed by treatment by applying a gel formulation containing the particles using a soft bristled toothbrush, brushing 1 min on each side and leaving the specimen to rest for 3 min. Treatment was repeated four times during one day and samples were incubated at 37 °C in artificial saliva.Results:In vitro tests and degradation studies showed that ACP-Mg particles induced formation of Hydroxyapatite (HA). ICP-OES, XRD and SEM showed that there was a rapid release of all ions up to 6 hours followed by a re-precipitation of HA at 24 hours with a lower Mg-content. The crystallinity increased with time as the concentration of all ions decreased in the solutions. Morphological evaluation for the in-vitro tests showed that HA-like structures formed already after 24 hours on the dentine surface. Cross-sections revealed that the particles reached as far as 80 µm from the surface and tubules, fully occluded by HA-like structures, was visible at comparable depths after 7 days.Conclusions:ACP-Mg particles can be used to reduce dentine hypersensitivity by effective occlusion of dentine tubules via rapid formation of surface and intra-tubular HA.References:1. Splieth CH, Tachou A. 2013. Epidemiology of dentin hypersensitivity. Clin Oral Investig. 17:3–8.
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| 10. |
- Berg, Camilla, et al.
(författare)
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Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity : A Mode of Action Study
- 2020
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Ingår i: ACS Biomaterials Science & Engineering. - : AMER CHEMICAL SOC. - 2373-9878. ; 6:6, s. 3599-3607
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Tidskriftsartikel (refereegranskat)abstract
- Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.
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