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Xu C, Uahengo G, Rudnicki C, Hung C, Huang A, Xu Q, Chen Y, Halaney DL, Garay JE, Mangolini L, Aguilar G, Liu HH. Nanocrystalline Yttria-Stabilized Zirconia Ceramics for Cranial Window Applications. ACS APPLIED BIO MATERIALS 2022; 5:2664-2675. [PMID: 35671525 DOI: 10.1021/acsabm.2c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Transparent yttria-stabilized zirconia (YSZ) ceramics are promising for cranial window applications because of their good mechanical and optical properties as well as biocompatibility. YSZ discs with different yttria concentrations were either processed via current-activated pressure-assisted densification (CAPAD) using commercial nanoparticles or densified via spark plasma sintering (SPS) using pyrolysis-synthesized nanoparticles in-house. This study provided critical results to screen composition, processing, microstructure, and cytocompatibility of transparent YSZ discs for cranial window applications. CAPAD-processed YSZ discs with 6 or 8 mol % yttria (6YSZ and 8YSZ) and SPS-densified YSZ discs with 4 mol % yttria (4YSZ_P) showed 200-350 nm polycrystalline grains containing 20-30 nm crystallite domains. SPS-densified YSZ discs with 8 mol % yttria (8YSZ_P) showed larger polycrystalline grains of 819 ± 155 nm with 29 ± 5 nm crystallite domains. CAPAD-processed YSZ discs with 3 mol % yttria (3YSZ) showed 39 ± 9 nm grains. Bone-marrow-derived stem cells (BMSCs) on the polished YSZ discs showed statistically higher spreading areas than those on the unpolished YSZ discs of the same compositions. Generally, polished 8YSZ, 4YSZ_P, and 8YSZ_P discs and unpolished 8YSZ_R, 4YSZ_PR, and 8YSZ_PR discs had lower average cell adhesion densities than other YSZ discs under direct contact conditions. Under indirect contact conditions, all the YSZ disc groups showed similar average cell adhesion densities to the Cell-only control. The groups of polished 4YSZ_P and 8YSZ_P discs, unpolished 4YSZ_PR and 8YSZ_PR discs, and particle control of 8YSZ_Pnp showed higher Y3+ ion concentrations than other groups. No mineral deposition was detected on the polished YSZ discs after cell culture. Considering multiple factors such as cytocompatibility, cell adhesion density, Y3+ ion release, mineral deposition, and optical transparency collectively, 8YSZ may be the best candidate for the cranial window applications. Further studies are needed to evaluate the long-term transparency and biocompatibility of YSZ discs.
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Affiliation(s)
- Changlu Xu
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States
| | - Gottlieb Uahengo
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093, United States
| | - Christopher Rudnicki
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Chengi Hung
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Aaron Huang
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Queenie Xu
- Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States
| | - Yiqing Chen
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States
| | - David L Halaney
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Javier E Garay
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, California 92093, United States
| | - Lorenzo Mangolini
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States.,Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Guillermo Aguilar
- Department of Mechanical Engineering, University of California, Riverside, Riverside, California 92521, United States
| | - Huinan Hannah Liu
- Materials Science and Engineering Program, University of California, Riverside, Riverside, California 92521, United States.,Department of Bioengineering, University of California, Riverside, Riverside, California 92521, United States.,Stem Cell Center, University of California, Riverside, Riverside, California 92521, United States
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2
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Cano-Velázquez MS, Bon J, Llamazares M, Camacho-López S, Aguilar G, Hernández-Cordero J, Trujillo M. Experimental and computational model approach to assess the photothermal effects in transparent nanocrystalline yttria stabilized zirconia cranial implant. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 221:106896. [PMID: 35617809 DOI: 10.1016/j.cmpb.2022.106896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 05/12/2022] [Accepted: 05/15/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE In the last few years, we have been exploring the use of transparent nanocrystalline yttria-stabilized zirconia (nc-YSZ) ceramics as a biomedical transparent cranial implant, referred as the "Window to the Brain" (WttB). The WttB aims at providing chronical optical access to the brain for diagnostics and therapeutic procedures and it has shown to provide an effective means to obtain enhanced results from optical imaging techniques. The objective of this work is to explore the photothermal effects of the Wttb produced when it is irradiated by a laser source. METHODS We make experimental and computer models. The thermal effects of laser irradiation on the nc-YSZ samples were evaluated upon registering the induced temperature changes by means of thermal imaging. The computer models try to mimic the experimental models using a similar geometry, reproducing the physical situation by a couple thermal-optical problem and adjusting the main parameters from the experimental results. RESULTS Experimental and computational coincides in results: Temperatures at the bottom surface of the implant does not exceed those which produce thermal damage. The quantitative comparison between experimental and computational models show that differences in results are under a reasonable value of 5% and qualitatively we observe a similar behavior. The results provide optimum values for the thermal-optical nc-YSZ parameters considering a linear and exponential relationship with temperature for the absorption coefficient: The thermal conductivity is k = 2.13 W/m·K and the absorption coefficient α varies from 426 to 526 m-1 with the linear relationship, and k = 2.04 W/m·K and α ∈ [433,502] m-1 with the exponential. The reflection coefficient is R = 19% in both cases. CONCLUSIONS The temperatures achieved in the nc-YSZ during the laser irradiation are suitable for biomedical applications. The combination of experimental and computational models contributes to build a clinically oriented model with the thermal-optical parameters values stablished and to determine their influence in results. Specifically, the absorption coefficient of the nc-YSZ samples is the most influent parameter in the obtained temperatures. Moreover, this combination provides a method to evaluate the relevant thermal-optical parameters of nc-YSZ samples obtained with different manufacturing processes.
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Affiliation(s)
- Mildred S Cano-Velázquez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Jose Bon
- Food Technology Department, Universitat Politècnica de València, Valencia, Spain
| | - M Llamazares
- Department of Applied Mathematics, BioMIT, Universitat Politècnica de València, Valencia, Spain
| | - Santiago Camacho-López
- Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, B.C., México
| | - Guillermo Aguilar
- J. Mike Walker '66 Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA
| | - Juan Hernández-Cordero
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Macarena Trujillo
- Department of Applied Mathematics, BioMIT, Universitat Politècnica de València, Valencia, Spain.
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3
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Wang Y, Xi L. Chronic cranial window for photoacoustic imaging: a mini review. Vis Comput Ind Biomed Art 2021; 4:15. [PMID: 34037873 PMCID: PMC8155166 DOI: 10.1186/s42492-021-00081-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 04/27/2021] [Indexed: 12/31/2022] Open
Abstract
Photoacoustic (PA) microscopy is being increasingly used to visualize the microcirculation of the brain cortex at the micron level in living rodents. By combining it with long-term cranial window techniques, vasculature can be monitored over a period of days extending to months through a field of view. To fulfill the requirements of long-term in vivo PA imaging, the cranial window must involve a simple and rapid surgical procedure, biological compatibility, and sufficient optical-acoustic transparency, which are major challenges. Recently, several cranial window techniques have been reported for longitudinal PA imaging. Here, the development of chronic cranial windows for PA imaging is reviewed and its technical details are discussed, including window installation, imaging quality, and longitudinal stability.
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Affiliation(s)
- Yongchao Wang
- School of Physics, University of Electronic Science and Technology of China, Chengdu, 610054, Sichuan, China.,Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China
| | - Lei Xi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, Guangdong, China.
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4
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Halaney DL, Katta N, Fallah H, Aguilar G, Milner TE. Group Refractive Index of Nanocrystalline Yttria-Stabilized Zirconia Transparent Cranial Implants. Front Bioeng Biotechnol 2021; 9:619686. [PMID: 33869149 PMCID: PMC8044953 DOI: 10.3389/fbioe.2021.619686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/02/2021] [Indexed: 11/18/2022] Open
Abstract
Transparent “Window to the Brain” (WttB) cranial implants made from a biocompatible ceramic, nanocrystalline Yttria-Stabilized Zirconia (nc-YSZ), were recently reported. These reports demonstrated chronic brain imaging across the implants in mice using optical coherence tomography (OCT) and laser speckle imaging. However, optical properties of these transparent cranial implants are neither completely characterized nor completely understood. In this study, we measure optical properties of the implant using a swept source OCT system with a spectral range of 136 nm centered at 1,300 nm to characterize the group refractive index of the nc-YSZ window, over a narrow range of temperatures at which the implant may be used during imaging or therapy (20–43°C). Group refractive index was found to be 2.1–2.2 for OCT imaging over this temperature range. Chromatic dispersion for this spectral range was observed to vary over the sample, sometimes flipping signs between normal and anomalous dispersion. These properties of nc-YSZ should be considered when designing optical systems and procedures that propagate light through the window, and when interpreting OCT brain images acquired across the window.
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Affiliation(s)
- David L Halaney
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Nitesh Katta
- Laboratory of Thomas Milner, Department of Biomedical Engineering, University of Texas, Austin, TX, United States
| | | | - Guillermo Aguilar
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Thomas E Milner
- Laboratory of Thomas Milner, Department of Biomedical Engineering, University of Texas, Austin, TX, United States
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Cramer SW, Carter RE, Aronson JD, Kodandaramaiah SB, Ebner TJ, Chen CC. Through the looking glass: A review of cranial window technology for optical access to the brain. J Neurosci Methods 2021; 354:109100. [PMID: 33600850 PMCID: PMC8100903 DOI: 10.1016/j.jneumeth.2021.109100] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 02/07/2023]
Abstract
Deciphering neurologic function is a daunting task, requiring understanding the neuronal networks and emergent properties that arise from the interactions among single neurons. Mechanistic insights into neuronal networks require tools that simultaneously assess both single neuron activity and the consequent mesoscale output. The development of cranial window technologies, in which the skull is thinned or replaced with a synthetic optical interface, has enabled monitoring neuronal activity from subcellular to mesoscale resolution in awake, behaving animals when coupled with advanced microscopy techniques. Here we review recent achievements in cranial window technologies, appraise the relative merits of each design and discuss the future research in cranial window design.
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Affiliation(s)
- Samuel W Cramer
- Department of Neurosurgery, University of Minnesota, 420 Delaware St SE, Mayo D429, MMC 96, Twin Cities, Minneapolis, MN, 55455, USA
| | - Russell E Carter
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA
| | - Justin D Aronson
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA
| | - Suhasa B Kodandaramaiah
- Department of Mechanical Engineering, University of Minnesota, Twin Cities, MN, USA; Department of Biomedical Engineering, University of Minnesota, Twin Cities, MN, USA; Graduate Program in Neuroscience, University of Minnesota, Twin Cities, MN, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Twin Cities, Room 421, 2001 Sixth Street S.E., Minneapolis, MN, 55455 MN, USA.
| | - Clark C Chen
- Department of Neurosurgery, University of Minnesota, 420 Delaware St SE, Mayo D429, MMC 96, Twin Cities, Minneapolis, MN, 55455, USA.
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Halaney DL, Jonak CR, Liu J, Davoodzadeh N, Cano-Velázquez MS, Ehtiyatkar P, Park H, Binder DK, Aguilar G. Chronic Brain Imaging Across a Transparent Nanocrystalline Yttria-Stabilized-Zirconia Cranial Implant. Front Bioeng Biotechnol 2020; 8:659. [PMID: 32695757 PMCID: PMC7339873 DOI: 10.3389/fbioe.2020.00659] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 05/28/2020] [Indexed: 12/28/2022] Open
Abstract
Repeated non-diffuse optical imaging of the brain is difficult. This is due to the fact that the cranial bone is highly scattering and thus a strong optical barrier. Repeated craniotomies increase the risk of complications and may disrupt the biological systems being imaged. We previously introduced a potential solution in the form of a transparent ceramic cranial implant called the Window to the Brain (WttB) implant. This implant is made of nanocrystalline Yttria-Stabilized Zirconia (nc-YSZ), which possesses the requisite mechanical strength to serve as a permanent optical access window in human patients. In this present study, we demonstrate repeated brain imaging of n = 5 mice using both OCT and LSI across the WttB implant over 4 weeks. The main objectives are to determine if the WttB implant allows for chronic OCT imaging, and to shed further light on the question of whether optical access provided by the WttB implant remains stable over this duration in the body. The Window to the Brain implant allowed for stable repeated imaging of the mouse brain with Optical Coherence Tomography over 28 days, without loss of signal intensity. Repeated Laser Speckle Imaging was also possible over this timeframe, but signal to noise ratio and the sharpness of vessels in the images decreased with time. This can be partially explained by elevated blood flow during the first imaging session in response to trauma from the surgery, which was also detected by OCT flow imaging. These results are promising for long-term optical access through the WttB implant, making feasible chronic in vivo studies in multiple neurological models of brain disease.
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Affiliation(s)
- David L Halaney
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Carrie R Jonak
- Laboratory of Devin Binder, Division of Biomedical Sciences, University of California, Riverside, Riverside, CA, United States
| | - Junze Liu
- Laboratory of Hyle Park, Department of Bioengineering, University of California, Riverside, Riverside, CA, United States
| | - Nami Davoodzadeh
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
| | - Mildred S Cano-Velázquez
- Laboratory of Juan Hernandez-Cordero, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Pasha Ehtiyatkar
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States.,Department of Neuroscience, University of California, Riverside, Riverside, CA, United States
| | - Hyle Park
- Laboratory of Hyle Park, Department of Bioengineering, University of California, Riverside, Riverside, CA, United States
| | - Devin K Binder
- Laboratory of Devin Binder, Division of Biomedical Sciences, University of California, Riverside, Riverside, CA, United States
| | - Guillermo Aguilar
- Laboratory of Guillermo Aguilar, Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, United States
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7
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A Robust Method for Adjustment of Laser Speckle Contrast Imaging during Transcranial Mouse Brain Visualization. PHOTONICS 2019. [DOI: 10.3390/photonics6030080] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Laser speckle imaging (LSI) is a well-known and useful approach for the non-invasive visualization of flows and microcirculation localized in turbid scattering media, including biological tissues (such as brain vasculature, skin capillaries etc.). Despite an extensive use of LSI for brain imaging, the LSI technique has several critical limitations. One of them is associated with inability to resolve a functionality of vessels. This limitation also leads to the systematic error in the quantitative interpretation of values of speckle contrast obtained for different vessel types, such as sagittal sinus, arteries, and veins. Here, utilizing a combined use of LSI and fluorescent intravital microscopy (FIM), we present a simple and robust method to overcome the limitations mentioned above for the LSI approach. The proposed technique provides more relevant, abundant, and valuable information regarding perfusion rate ration between different types of vessels that makes this method highly useful for in vivo brain surgical operations.
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8
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Cano-Velázquez MS, Davoodzadeh N, Halaney D, Jonak CR, Binder DK, Hernández-Cordero J, Aguilar G. Enhanced near infrared optical access to the brain with a transparent cranial implant and scalp optical clearing. BIOMEDICAL OPTICS EXPRESS 2019; 10:3369-3379. [PMID: 31467783 PMCID: PMC6706046 DOI: 10.1364/boe.10.003369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 05/12/2019] [Accepted: 05/29/2019] [Indexed: 06/10/2023]
Abstract
We report on the enhanced optical transmittance in the NIR wavelength range (900 to 2400 nm) offered by a transparent Yttria-stabilized zirconia (YSZ) implant coupled with optical clearing agents (OCAs). The enhancement in optical access to the brain is evaluated upon comparing ex-vivo transmittance measurements of mice native skull and the YSZ cranial implant with scalp and OCAs. An increase in transmittance of up to 50% and attenuation lengths of up to 2.4 mm (i.e., a five-fold increase in light penetration) are obtained with the YSZ implant and the OCAs. The use of this ceramic implant and the biocompatible optical clearing agents offer attractive features for NIR optical techniques for brain theranostics.
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Affiliation(s)
| | - Nami Davoodzadeh
- Department of Mechanical Engineering, University of California, Riverside, CA,
USA
| | - David Halaney
- Department of Mechanical Engineering, University of California, Riverside, CA,
USA
| | - Carrie R. Jonak
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA,
USA
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA,
USA
| | - Juan Hernández-Cordero
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México
| | - Guillermo Aguilar
- Department of Mechanical Engineering, University of California, Riverside, CA,
USA
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9
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Davoodzadeh N, Cano-Velázquez MS, Halaney DL, Jonak CR, Binder DK, Aguilar G. Optical Access to Arteriovenous Cerebral Microcirculation Through a Transparent Cranial Implant. Lasers Surg Med 2019; 51:920-932. [PMID: 31236997 DOI: 10.1002/lsm.23127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2019] [Indexed: 01/20/2023]
Abstract
BACKGROUND AND OBJECTIVE Microcirculation plays a critical role in physiologic processes and several disease states. Laser speckle imaging (LSI) is a full-field, real-time imaging technique capable of mapping microvessel networks and providing relative flow velocity within the vessels. In this study, we demonstrate that LSI combine with multispectral reflectance imaging (MSRI), which allows for distinction between veins and arteries in the vascular flow maps produced by LSI. We apply this combined technique to mouse cerebral vascular network in vivo, comparing imaging through the skull, to the dura mater and brain directly through a craniectomy, and through a transparent cranial "Window to the Brain" (WttB) implant. STUDY DESIGN/MATERIALS AND METHODS The WttB implant used in this study is made of a nanocrystalline Yttria-Stabilized-Zirconia ceramic. MSRI was conducted using white-light illumination and filtering the reflected light for 560, 570, 580, 590, 600, and 610 nm. LSI was conducted using an 810 nm continuous wave near-infrared laser with incident power of 100 mW, and the reflected speckle pattern was captured by a complementary metal-oxide-semiconductor (CMOS) camera. RESULTS Seven vessel branches were analyzed and comparison was made between imaging through the skull, craniectomy, and WttB implant. Through the skull, MSRI did not detect any vessels, and LSI could not image microvessels. Imaging through the WttB implant, MSRI was able to identify veins versus arteries, and LSI was able to image microvessels with only slightly higher signal-to-noise ratio and lower sharpness than imaging the brain through a craniectomy. CONCLUSIONS This study demonstrates the ability to perform MSRI-LSI across a transparent cranial implant, to allow for cerebral vascular networks to be mapped, including microvessels. These images contain additional information such as vein-artery separation and relative blood flow velocities, information which is of value scientifically and medically. The WttB implant provides substantial improvements over imaging through the murine cranial bone, where microvessels are not visible and MSRI cannot be performed. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Nami Davoodzadeh
- Department of Mechanical Engineering, University of California, Bourns Hall A342 900 University Ave., Riverside, California, 92521
| | - Mildred S Cano-Velázquez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, Mexico City, 04510, Mexico
| | - David L Halaney
- Department of Mechanical Engineering, University of California, Bourns Hall A342 900 University Ave., Riverside, California, 92521
| | - Carrie R Jonak
- Division of Biomedical Sciences, School of Medicine, University of California, 1126 Webber Hall 900 University Ave., Riverside, California, 92521
| | - Devin K Binder
- Division of Biomedical Sciences, School of Medicine, University of California, 1126 Webber Hall 900 University Ave., Riverside, California, 92521
| | - Guillermo Aguilar
- Department of Mechanical Engineering, University of California, Bourns Hall A342 900 University Ave., Riverside, California, 92521
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10
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Davoodzadeh N, Cano-Velázquez MS, Halaney DL, Sabzeghabae A, Uahengo G, Garay JE, Aguilar G. Characterization of ageing resistant transparent nanocrystalline yttria-stabilized zirconia implants. J Biomed Mater Res B Appl Biomater 2019; 108:709-716. [PMID: 31172661 DOI: 10.1002/jbm.b.34425] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/01/2019] [Accepted: 05/17/2019] [Indexed: 12/14/2022]
Abstract
The "Window to the Brain" is a transparent cranial implant under development, based on nanocrystalline yttria-stabilized zirconia (nc-YSZ) transparent ceramic material. Previous work has demonstrated the feasibility of this material to facilitate brain imaging over time, but the long-term stability of the material over decades in the body is unknown. In this study, the low-temperature degradation (LTD) of nc-YSZ of 3, 6, and 8 mol % yttria is compared before and after accelerated ageing treatments following ISO standards for assessing the ageing resistance of zirconia ceramics. After 100 hr of accelerated ageing (equivalent to many decades of ageing in the body), the samples do not show any signs of phase transformation to monoclinic by X-ray diffraction and micro-Raman spectroscopy. Moreover, the mechanical hardness of the samples did not decrease, and changes in optical transmittance from 500 to 1000 nm due to ageing treatments was minimal (below 3% for all samples), and unlikely to be due to phase transformation of surface crystals to monoclinic. These results indicate the nc-YSZ has excellent ageing resistance and can withstand long-term implantation conditions without exhibiting LTD.
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Affiliation(s)
- Nami Davoodzadeh
- Department of Mechanical Engineering, University of California - Riverside, Riverside, California
| | - Mildred S Cano-Velázquez
- Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México, Mexico
| | - David L Halaney
- Department of Mechanical Engineering, University of California - Riverside, Riverside, California
| | - Ariana Sabzeghabae
- Department of Mechanical Engineering, University of California - Riverside, Riverside, California
| | - Gottlieb Uahengo
- Department of Mechanical and Aerospace Engineering, University of California - San Diego, La Jolla, California
| | - Javier E Garay
- Department of Mechanical and Aerospace Engineering, University of California - San Diego, La Jolla, California
| | - Guillermo Aguilar
- Department of Mechanical Engineering, University of California - Riverside, Riverside, California
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