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Presley KF, Falcucci T, Shaidani S, Fitzpatrick V, Barry J, Ly JT, Dalton MJ, Grusenmeyer TA, Kaplan DL. Engineered porosity for tissue-integrating, bioresorbable lifetime-based phosphorescent oxygen sensors. Biomaterials 2023; 301:122286. [PMID: 37643490 DOI: 10.1016/j.biomaterials.2023.122286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/05/2023] [Accepted: 08/18/2023] [Indexed: 08/31/2023]
Abstract
Versatile silk protein-based material formats were studied to demonstrate bioresorbable, implantable optical oxygen sensors that can integrate with the surrounding tissues. The ability to continuously monitor tissue oxygenation in vivo is desired for a range of medical applications. Silk was chosen as the matrix material due to its excellent biocompatibility, its unique chemistry that facilitates interactions with chromophores, and the potential to tune degradation time without altering chemical composition. A phosphorescent Pd (II) benzoporphyrin chromophore was incorporated to impart oxygen sensitivity. Organic solvent-based processing methods using 1,1,1,3,3,3-hexafluoro-2-propanol were used to fabricate: 1) silk-chromophore films with varied thickness and 2) silk-chromophore sponges with interconnected porosity. All compositions were biocompatible and exhibited photophysical properties with oxygen sensitivities (i.e., Stern-Volmer quenching rate constants of 2.7-3.2 × 104 M-1) useful for monitoring physiological tissue oxygen levels and for detecting deviations from normal behavior (e.g., hyperoxia). The potential to tune degradation time without significantly impacting photophysical properties was successfully demonstrated. Furthermore, the ability to consistently monitor tissue oxygenation in vivo was established via a multi-week rodent study. Histological assessments indicated successful tissue integration for the sponges, and this material format responded more quickly to various oxygen challenges than the film samples.
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Affiliation(s)
- Kayla F Presley
- Air Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, Wright-Patterson AFB, Ohio, 45433, United States; UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH, 45432, United States.
| | - Thomas Falcucci
- Tufts University, Biomedical Engineering, 4 Colby Street, Medford, MA, 02155, United States
| | - Sawnaz Shaidani
- Tufts University, Biomedical Engineering, 4 Colby Street, Medford, MA, 02155, United States
| | - Vincent Fitzpatrick
- Tufts University, Biomedical Engineering, 4 Colby Street, Medford, MA, 02155, United States
| | - Jonah Barry
- Tufts University, Biomedical Engineering, 4 Colby Street, Medford, MA, 02155, United States
| | - Jack T Ly
- Air Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, Wright-Patterson AFB, Ohio, 45433, United States; UES, Inc., 4401 Dayton-Xenia Road, Dayton, OH, 45432, United States
| | - Matthew J Dalton
- Air Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, Wright-Patterson AFB, Ohio, 45433, United States
| | - Tod A Grusenmeyer
- Air Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, Wright-Patterson AFB, Ohio, 45433, United States.
| | - David L Kaplan
- Tufts University, Biomedical Engineering, 4 Colby Street, Medford, MA, 02155, United States.
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Zharskaia NA, Solomatina AI, Liao YC, Galenko EE, Khlebnikov AF, Chou PT, Chelushkin PS, Tunik SP. Aggregation-Induced Ignition of Near-Infrared Phosphorescence of Non-Symmetric [Pt(C^N*N’^C’)] Complex in Poly(caprolactone)-based Block Copolymer Micelles: Evaluating the Alternative Design of Near-Infrared Oxygen Biosensors. BIOSENSORS 2022; 12:bios12090695. [PMID: 36140080 PMCID: PMC9496585 DOI: 10.3390/bios12090695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/13/2022] [Accepted: 08/24/2022] [Indexed: 02/03/2023]
Abstract
In the present work, we described the preparation and characterization of the micelles based on amphiphilic poly(ε-caprolactone-block-ethylene glycol) block copolymer (PCL-b-PEG) loaded with non-symmetric [Pt(C^N*N’^C’)] complex (Pt1) (where C^N*N’^C’: 6-(phenyl(6-(thiophene-2-yl)pyridin-2-yl)amino)-2-(tyophene-2-yl)nicotinate). The obtained nanospecies displayed the ignition of near-infrared (NIR) phosphorescence upon an increase in the content of the platinum complexes in the micelles, which acted as the major emission component at 12 wt.% of Pt1. Emergence of the NIR band at 780 nm was also accompanied by a 3-fold growth of the quantum yield and an increase in the two-photon absorption cross-section that reached the value of 450 GM. Both effects are believed to be the result of progressive platinum complex aggregation inside hydrophobic poly(caprolactone) cores of block copolymer micelles, which has been ascribed to aggregation induced emission (AIE). The resulting phosphorescent (Pt1@PCL-b-PEG) micelles demonstrated pronounced sensitivity towards molecular oxygen, the key intracellular bioanalyte. The detailed photophysical analysis of the AIE phenomena revealed that the NIR emission most probably occurred due to the excimeric excited state of the 3MMLCT character. Evaluation of the Pt1@PCL-b-PEG efficacy as a lifetime intracellular oxygen biosensor carried out in CHO-K1 live cells demonstrated the linear response of the probe emission lifetime towards this analyte accompanied by a pronounced influence of serum albumin on the lifetime response. Nevertheless, Pt1@PCL-b-PEG can serve as a semi-quantitative lifetime oxygen nanosensor. The key result of this study consists of the demonstration of an alternative approach for the preparation of NIR biosensors by taking advantage of in situ generation of NIR emission due to the nanoconfined aggregation of Pt (II) complexes inside the micellar nanocarriers.
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Affiliation(s)
- Nina A. Zharskaia
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
| | - Anastasia I. Solomatina
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
| | - Yu-Chan Liao
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
| | - Ekaterina E. Galenko
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
| | - Alexander F. Khlebnikov
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
| | - Pi-Tai Chou
- Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan
- Correspondence: (P.-T.C.); (P.S.C.)
| | - Pavel S. Chelushkin
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
- Correspondence: (P.-T.C.); (P.S.C.)
| | - Sergey P. Tunik
- Institute of Chemistry, St. Petersburg State University, Universitetskii Av., 26, 198504 St. Petersburg, Russia
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The Influence of Topical Vasodilator-Induced Pharmacologic Delay on Cutaneous Flap Viability and Vascular Remodeling. Plast Reconstr Surg 2022; 149:629-637. [PMID: 35041631 PMCID: PMC9102222 DOI: 10.1097/prs.0000000000008829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND Surgical delay is a well-described technique to improve survival of random and pedicled cutaneous flaps. The aim of this study was to test the topical agents minoxidil and iloprost as agents of pharmacologic delay to induce vascular remodeling and decrease overall flap necrosis as an alternative to surgical delay. METHODS Seven groups were studied (n = 8 in each group), including the following: vehicle, iloprost, or minoxidil before treatment only; vehicle, iloprost, or minoxidil before and after treatment; and a standard surgical delay group as a positive control. Surgical flaps (caudally based modified McFarlane myocutaneous skin flaps) were elevated after 14 days of pretreatment, reinset isotopically, and observed at various time points until postoperative day 7. Gross viability, histology, Doppler blood flow, perfusion imaging, tissue oxygenation measurement, and vascular casting were performed for analysis. RESULTS Pharmacologic delay with preoperative application of topical minoxidil or iloprost was found to have comparable flap viability when compared to surgical delay. Significantly increased viability in all treatment groups was observed when compared with vehicle. Continued postoperative treatment with topical agents had no effect on flap viability. The mechanism of improved flap viability was inducible increases in flap blood volume and perfusion rather than the acute vasodilatory effects of the topical agents or decreased flap hypoxia. CONCLUSIONS Preoperative topical application of the vasodilators minoxidil or iloprost improved flap viability comparably to surgical delay. Noninvasive pharmacologic delay may reduce postoperative complications without the need for an additional operation. CLINICAL RELEVANCE STATEMENT Preoperative use of topical vasodilators may lead to improved flap viability without the need for a surgical delay procedure. This study may inform future clinical trials examining utility of preoperative topical vasodilators in flap surgery.
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Unruh RM, Bornhoeft LR, Nichols SP, Wisniewski NA, McShane MJ. Inorganic-Organic Interpenetrating Network Hydrogels as Tissue-Integrating Luminescent Implants: Physicochemical Characterization and Preclinical Evaluation. Macromol Biosci 2022; 22:e2100380. [PMID: 34847287 PMCID: PMC8930476 DOI: 10.1002/mabi.202100380] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/23/2021] [Indexed: 11/07/2022]
Abstract
Sensors capable of accurate, continuous monitoring of biochemistry are crucial to the realization of personalized medicine on a large scale. Great strides have been made to enhance tissue compatibility of long-term in vivo biosensors using biomaterials strategies such as tissue-integrating hydrogels. However, the low level of oxygen in tissue presents a challenge for implanted devices, especially when the biosensing function relies on oxygen as a measure-either as a primary analyte or as an indirect marker to transduce levels of other biomolecules. This work presents a method of fabricating inorganic-organic interpenetrating network (IPN) hydrogels to optimize the oxygen transport through injectable biosensors. Capitalizing on the synergy between the two networks, various physicochemical properties (e.g., swelling, glass transition temperature, and mechanical properties) are shown to be independently adjustable while maintaining a 250% increase in oxygen permeability relative to poly(2-hydroxyethyl methacrylate) controls. Finally, these gels, when functionalized with a Pd(II) benzoporphyrin phosphor, track tissue oxygen in real time for 76 days as subcutaneous implants in a porcine model while promoting tissue ingrowth and minimizing fibrosis around the implant. These findings support IPN networks for fine-tuned design of implantable biomaterials in personalized medicine and other biomedical applications.
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Affiliation(s)
- Rachel M. Unruh
- 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX 77843, USA
| | | | | | | | - Michael J. McShane
- 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX 77843, USA
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Turner BL, Senevirathne S, Kilgour K, McArt D, Biggs M, Menegatti S, Daniele MA. Ultrasound-Powered Implants: A Critical Review of Piezoelectric Material Selection and Applications. Adv Healthc Mater 2021; 10:e2100986. [PMID: 34235886 DOI: 10.1002/adhm.202100986] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/15/2021] [Indexed: 12/14/2022]
Abstract
Ultrasound-powered implants (UPIs) represent cutting edge power sources for implantable medical devices (IMDs), as their powering strategy allows for extended functional lifetime, decreased size, increased implant depth, and improved biocompatibility. IMDs are limited by their reliance on batteries. While batteries proved a stable power supply, batteries feature relatively large sizes, limited life spans, and toxic material compositions. Accordingly, energy harvesting and wireless power transfer (WPT) strategies are attracting increasing attention by researchers as alternative reliable power sources. Piezoelectric energy scavenging has shown promise for low power applications. However, energy scavenging devices need be located near sources of movement, and the power stream may suffer from occasional interruptions. WPT overcomes such challenges by more stable, on-demand power to IMDs. Among the various forms of WPT, ultrasound powering offers distinct advantages such as low tissue-mediated attenuation, a higher approved safe dose (720 mW cm-2 ), and improved efficiency at smaller device sizes. This study presents and discusses the state-of-the-art in UPIs by reviewing piezoelectric materials and harvesting devices including lead-based inorganic, lead-free inorganic, and organic polymers. A comparative discussion is also presented of the functional material properties, architecture, and performance metrics, together with an overview of the applications where UPIs are being deployed.
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Affiliation(s)
- Brendan L. Turner
- Joint Department of Biomedical Engineering North Carolina State University and University of North Carolina Chapel Hill, 911 Oval Dr. Raleigh NC 27695 USA
| | - Seedevi Senevirathne
- The Patrick G Johnston Centre for Cancer Research Queen's University 97 Lisburn Rd Belfast BT9 7AE UK
| | - Katie Kilgour
- Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh NC 27695 USA
| | - Darragh McArt
- The Patrick G Johnston Centre for Cancer Research Queen's University 97 Lisburn Rd Belfast BT9 7AE UK
| | - Manus Biggs
- Centre for Research in Medical Devices National University of Ireland Newcastle Road Galway H91 W2TY Ireland
| | - Stefano Menegatti
- Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh NC 27695 USA
| | - Michael A. Daniele
- Joint Department of Biomedical Engineering North Carolina State University and University of North Carolina Chapel Hill, 911 Oval Dr. Raleigh NC 27695 USA
- Department of Electrical and Computer Engineering North Carolina State University 890 Oval Dr. Raleigh NC 27695 USA
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6
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Detection of flap tissue ischemia in a rat model: Real-time monitoring of changes in oxygenation and perfusion through injectable biosensors. Surgery 2020; 168:926-934. [PMID: 32653202 DOI: 10.1016/j.surg.2020.04.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/16/2020] [Accepted: 04/16/2020] [Indexed: 11/23/2022]
Abstract
BACKGROUND The success of surgical flaps is improved by timely correction of vascular compromise. Current monitoring methods are labor or cost intensive or have limited clinical benefit. We hypothesize that injectable oxygen sensors can identify acute vascular compromise. The purpose of this study was to use a long-term, real-time method of tissue oxygenation detection in a rat flap model with vascular manipulation. METHODS Sensors incorporated benzo-porphyrin dye into a microporous hydrogel and were injected intradermally 1 day before flap elevation. Inspired oxygen was modulated between 100% and 12% to confirm sensor O2 sensitivity. Eight random flaps (4 cm wide, 8 cm long) were elevated. Sensor and clinical observation to temporary clamping of the flap vascular pedicle was recorded. Sodium fluorescein in saline was injected intraperitoneally on postoperative days 0, 3, and 7 with subsequent perfusion area analysis. RESULTS Tissue oxygen tension measurements reflected the changes in inspired oxygen levels. Clinical observation of the flaps did not show any significant change in color or temperature with pedicle clamping. However, clamping of the pedicle resulted in a significant decrease in sensor tissue oxygen tension within 70 seconds. CONCLUSION Oxygen monitoring of myocutaneous flaps is sensitive and can detect acute vascular occlusion. This technique is faster than current methods and offers a cost-effective and accurate means of monitoring surgical tissues.
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7
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Jung YH, Kim JU, Lee JS, Shin JH, Jung W, Ok J, Kim TI. Injectable Biomedical Devices for Sensing and Stimulating Internal Body Organs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907478. [PMID: 32104960 DOI: 10.1002/adma.201907478] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/15/2020] [Indexed: 06/10/2023]
Abstract
The rapid pace of progress in implantable electronics driven by novel technology has created devices with unconventional designs and features to reduce invasiveness and establish new sensing and stimulating techniques. Among the designs, injectable forms of biomedical electronics are explored for accurate and safe targeting of deep-seated body organs. Here, the classes of biomedical electronics and tools that have high aspect ratio structures designed to be injected or inserted into internal organs for minimally invasive monitoring and therapy are reviewed. Compared with devices in bulky or planar formats, the long shaft-like forms of implantable devices are easily placed in the organs with minimized outward protrusions via injection or insertion processes. Adding flexibility to the devices also enables effortless insertions through complex biological cavities, such as the cochlea, and enhances chronic reliability by complying with natural body movements, such as the heartbeat. Diverse types of such injectable implants developed for different organs are reviewed and the electronic, optoelectronic, piezoelectric, and microfluidic devices that enable stimulations and measurements of site-specific regions in the body are discussed. Noninvasive penetration strategies to deliver the miniscule devices are also considered. Finally, the challenges and future directions associated with deep body biomedical electronics are explained.
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Affiliation(s)
- Yei Hwan Jung
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Jong Uk Kim
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Ju Seung Lee
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Joo Hwan Shin
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Woojin Jung
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Jehyung Ok
- School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
| | - Tae-Il Kim
- School of Chemical Engineering, Department of Biomedical Engineering, and Biomedical Institute for Convergence at SKKU (BICS), Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea
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8
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Tejavibulya N, Colburn DAM, Marcogliese FA, Yang KA, Guo V, Chowdhury S, Stojanovic MN, Sia SK. Hydrogel Microfilaments toward Intradermal Health Monitoring. iScience 2019; 21:328-340. [PMID: 31698247 PMCID: PMC6889782 DOI: 10.1016/j.isci.2019.10.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/03/2019] [Accepted: 10/18/2019] [Indexed: 10/25/2022] Open
Abstract
Digital health promises a paradigm shift for medicine where biomarkers in individuals are continuously monitored to improve diagnosis and treatment of disease. To that end, a technology for minimally invasive quantification of endogenous analytes in bodily fluids will be required. Here, we describe a strategy for designing and fabricating hydrogel microfilaments that can penetrate the skin while allowing for optical fluorescence sensing. The polyacrylamide formulation was selected to provide high elastic modulus in the dehydrated state and optical transparency in the hydrated state. The microfilaments can be covalently tethered to a fluorescent aptamer to enable functional sensing. The microfilament array can penetrate the skin with low pain and without breaking, contact the dermal interstitial fluid, and be easily removed from the skin. In the future, hydrogel microfilaments could be integrated with a wearable fluorometer to serve as a platform for continuous, minimally invasive monitoring of intradermal biomarkers.
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Affiliation(s)
- Nalin Tejavibulya
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
| | - David A M Colburn
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
| | - Francis A Marcogliese
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
| | - Kyung-Ae Yang
- Division of Experimental Therapeutics, Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Vincent Guo
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
| | - Shilpika Chowdhury
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA
| | - Milan N Stojanovic
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA; Division of Experimental Therapeutics, Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Samuel K Sia
- Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, USA.
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Misra S, Shishehbor MH, Takahashi EA, Aronow HD, Brewster LP, Bunte MC, Kim ESH, Lindner JR, Rich K. Perfusion Assessment in Critical Limb Ischemia: Principles for Understanding and the Development of Evidence and Evaluation of Devices: A Scientific Statement From the American Heart Association. Circulation 2019; 140:e657-e672. [PMID: 31401843 PMCID: PMC7372288 DOI: 10.1161/cir.0000000000000708] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There are >12 million patients with peripheral artery disease in the United States. The most severe form of peripheral artery disease is critical limb ischemia (CLI). The diagnosis and management of CLI is often challenging. Ethnic differences in comorbidities and presentation of CLI exist. Compared with white patients, black and Hispanic patients have higher prevalence rates of diabetes mellitus and chronic renal disease and are more likely to present with gangrene, whereas white patients are more likely to present with ulcers and rest pain. A thorough evaluation of limb perfusion is important in the diagnosis of CLI because it can not only enable timely diagnosis but also reduce unnecessary invasive procedures in patients with adequate blood flow or among those with other causes for ulcers, including venous, neuropathic, or pressure changes. This scientific statement discusses the current tests and technologies for noninvasive assessment of limb perfusion, including the ankle-brachial index, toe-brachial index, and other perfusion technologies. In addition, limitations of the current technologies along with opportunities for improvement, research, and reducing disparities in health care for patients with CLI are discussed.
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10
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Kanick SC, Schneider PA, Klitzman B, Wisniewski NA, Rebrin K. Continuous monitoring of interstitial tissue oxygen using subcutaneous oxygen microsensors: In vivo characterization in healthy volunteers. Microvasc Res 2019; 124:6-18. [PMID: 30742844 PMCID: PMC6570499 DOI: 10.1016/j.mvr.2019.02.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 11/19/2022]
Abstract
Measurements of regional tissue oxygen serve as a proxy to monitor local perfusion and have the potential to guide therapeutic decisions in multiple clinical disciplines. Transcutaneous oximetry (tcpO2) is a commercially available noninvasive technique that uses an electrode to warm underlying skin tissue and measure the resulting oxygen tension at the skin surface. A novel approach is to directly measure interstitial tissue oxygen using subcutaneous oxygen microsensors composed of a biocompatible hydrogel carrier platform with embedded oxygen sensing molecules. After initial injection of the hydrogel into subcutaneous tissue, noninvasive optical measurements of phosphorescence-based emissions at the skin surface are used to sense oxygen in the subcutaneous interstitial space. The object of the present study was to characterize the in vivo performance of subcutaneous microsensors and compare with transcutaneous oximetry (tcpO2). Vascular occlusion tests were performed on the arms of 7 healthy volunteers, with repeated tests occurring 1 to 10 weeks after sensor injection, yielding 95 total tests for analysis. Comparative analysis characterized the response of both devices to decreases in tissue oxygen during occlusion and to increases in tissue oxygen following release of the occlusion. Results indicated: (I) time traces returned by microsensors and tcpO2 were highly correlated, with the median (interquartile range) correlation coefficient of r = 0.93 (0.10); (II) both microsensors and tcpO2 sensed a statistically significant decrease in normalized oxygen during occlusion (p < 0.001 for each device); (III) microsensors detected faster rates change (p < 0.001) and detected overshoot during recovery more frequently (38% vs. 4% of tests); (IV) inter-measurement analysis showed no correlation of baseline values between microsensors and tcpO2 (r = 0.03), but comparison of integrated oxygen dynamics showed similar variation in the normalized response to occlusion between devices (p = 0.06), (V) intra-measurement analysis revealed that microsensors detect greater physiological fluctuations than tcpO2 (p < 0.001) and may provide enhanced sensitivity to processes such as vasomotion. Additionally, the functional response of microsensors was not significantly different across time groupings (per month) post-injection (p = 0.61). Although the compared devices have differences in the mechanisms used to sense oxygen, these findings demonstrate that subcutaneous oxygen microsensors measure changes in interstitial tissue oxygen in human subjects in vivo.
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Affiliation(s)
| | | | - Bruce Klitzman
- Kenan Plastic Surgery Research Labs and Biomedical Engineering, Duke University, Durham, NC, USA
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11
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Long-Term In Vivo Oxygen Sensors for Peripheral Artery Disease Monitoring. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019. [PMID: 30178370 DOI: 10.1007/978-3-319-91287-5_56] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Tracking of tissue oxygenation around chronic foot wounds may help direct therapy decisions in patients with peripheral artery disease (PAD). Novel sensing technology to enable such monitoring was tested over 9 months in a Sinclair mini-pig model. No adverse events were observed over the entire study period. Systemic and acute hypoxia challenges were detected during each measurement period by the microsensors. The median time to locate the sensor signal was 13 s. Lumee Oxygen microsensors appear safe for long-term repeated oxygen measurements over 9 months.
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12
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Russell GM, Inamori D, Masai H, Tamaki T, Terao J. Luminescent and mechanical enhancement of phosphorescent hydrogel through cyclic insulation of platinum-acetylide crosslinker. Polym Chem 2019. [DOI: 10.1039/c9py00700h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An insulated Pt-acetylide complex was incorporated into a polymer network as a crosslinker to afford a phosphorescent gel.
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Affiliation(s)
- Go M. Russell
- Department of Basic Science
- Graduate School of Arts and Sciences
- The niversity of Tokyo
- Tokyo 153-8902
- Japan
| | - Daiki Inamori
- Department of Basic Science
- Graduate School of Arts and Sciences
- The niversity of Tokyo
- Tokyo 153-8902
- Japan
| | - Hiroshi Masai
- Department of Basic Science
- Graduate School of Arts and Sciences
- The niversity of Tokyo
- Tokyo 153-8902
- Japan
| | - Takashi Tamaki
- Department of Basic Science
- Graduate School of Arts and Sciences
- The niversity of Tokyo
- Tokyo 153-8902
- Japan
| | - Jun Terao
- Department of Basic Science
- Graduate School of Arts and Sciences
- The niversity of Tokyo
- Tokyo 153-8902
- Japan
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Reese AT, Cho EH, Klitzman B, Nichols SP, Wisniewski NA, Villa MM, Durand HK, Jiang S, Midani FS, Nimmagadda SN, O'Connell TM, Wright JP, Deshusses MA, David LA. Antibiotic-induced changes in the microbiota disrupt redox dynamics in the gut. eLife 2018; 7:35987. [PMID: 29916366 PMCID: PMC6008055 DOI: 10.7554/elife.35987] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/26/2018] [Indexed: 12/18/2022] Open
Abstract
How host and microbial factors combine to structure gut microbial communities remains incompletely understood. Redox potential is an important environmental feature affected by both host and microbial actions. We assessed how antibiotics, which can impact host and microbial function, change redox state and how this contributes to post-antibiotic succession. We showed gut redox potential increased within hours of an antibiotic dose in mice. Host and microbial functioning changed under treatment, but shifts in redox potentials could be attributed specifically to bacterial suppression in a host-free ex vivo human gut microbiota model. Redox dynamics were linked to blooms of the bacterial family Enterobacteriaceae. Ecological succession to pre-treatment composition was associated with recovery of gut redox, but also required dispersal from unaffected gut communities. As bacterial competition for electron acceptors can be a key ecological factor structuring gut communities, these results support the potential for manipulating gut microbiota through managing bacterial respiration. The gut is home to a large and diverse community of bacteria and other microbes, known as the gut microbiota. The makeup of this community is important for the health of both the host and its residents. For instance, many gut bacteria help to digest food or keep disease-causing bacteria in check. In return, the host provides them with nutrients. When this balance is disturbed, the host is exposed to risks such as infections. In particular, treatments with antibiotics that kill gut bacteria can lead to side effects like diarrhea, because the gut becomes recolonized with harmful bacteria including Clostridium difficile and Salmonella. Reese et al. have now investigated what happens to the gut environment after antibiotic treatment and how the gut microbiota recovers. Mice treated with broad-spectrum antibiotics showed an increase in the “redox potential” of their gut environment. Redox potential captures a number of measures of the chemical makeup of an environment, and provides an estimate for how efficiently some bacteria in that environment can grow. Some of the change in redox potential came from the host’s own immune system releasing chemicals as it reacted to the effects of the treatment. However, Reese et al. found that treating gut bacteria in an artificial gut – which has no immune system – also increased the redox potential. This experiment suggests that bacteria actively shape their chemical environment in the gut. After the treatment, bacteria that thrive under high redox potentials, which include some disease-causing species, recovered first and fastest. This, in turn, helped to bring redox potential back to how it was before the treatment. Although the gut’s chemical environment recovered, some bacterial species were wiped out by the antibiotic treatment. The microbiota only returned to its previous state when the treated mice were housed together with non-treated mice. This was expected because mice that live together commonly exchange microbes, for instance by eating each other’s feces, and the treated mice received new species to replenish their microbiota. These findings are important because they show that the chemical environment shapes and is shaped by the bacterial communities in the gut. Future research may investigate if altering redox potential in the gut could help to keep the microbiota healthier in infections and diseases of the digestive tract.
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Affiliation(s)
- Aspen T Reese
- Department of Biology, Duke University, Durham, United States.,Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Eugenia H Cho
- Department of Bioengineering, University of Pennsylvania, Philadelphia, United States
| | - Bruce Klitzman
- Department of Surgery, Duke University Medical Center, Durham, United States
| | | | | | - Max M Villa
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Heather K Durand
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Sharon Jiang
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States
| | - Firas S Midani
- Program in Computational Biology and Bioinformatics, Duke University, Durham, United States
| | - Sai N Nimmagadda
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Thomas M O'Connell
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, United States
| | - Justin P Wright
- Department of Biology, Duke University, Durham, United States
| | - Marc A Deshusses
- Department of Civil and Environmental Engineering, Duke University, Durham, United States
| | - Lawrence A David
- Department of Molecular Genetics and Microbiology, Duke University, Durham, United States.,Program in Computational Biology and Bioinformatics, Duke University, Durham, United States.,Department of Biomedical Engineering, Duke University, Durham, United States.,Center for Genomic and Computational Biology, Duke University, Durham, United States
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