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Chen Y, Shi J, Qiu H, You L, Xu P, Rao R, Wu M, Jia R. Characterization of Three Polysaccharide-Based Hydrogels Derived from Laminaria japonica and Their Hemostatic Properties. Mar Drugs 2024; 22:188. [PMID: 38667805 PMCID: PMC11051284 DOI: 10.3390/md22040188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 04/16/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
Three Laminaria japonica polysaccharides (LJPs) extracted via water extraction (LJP-W), acid extraction (LJP-A), and enzymatic extraction (LJP-E) were used as raw materials to be cross-linked with chitosan and polyvinyl alcohol to prepare hydrogels. Compared with conventional hydrogel systems, all three types of LJP-based polysaccharide hydrogels exhibited better swelling properties (14 times their original weight) and the absorption ability of simulated body fluid (first 2 h: 6-10%). They also demonstrated better rigidity and mechanical strength. Young's modulus of LJP-E was 4 times that of the blank. In terms of hemostatic properties, all three polysaccharide hydrogels did not show significant cytotoxic and hemolytic properties. The enzyme- and acid-extracted hydrogels (LJP-Gel-A and LJP-Gel-E) demonstrated better whole-blood coagulant ability compared with the water-extracted hydrogel (LJP-Gel-W), as evidenced by the whole blood coagulation index being half that of LJP-Gel-W. Additionally, the lactate dehydrogenase viabilities of LJP-Gel-A and LJP-Gel-E were significantly higher, at about four and three times those of water extraction, respectively. The above results suggested that LJP-Gel-A and LJP-Gel-E exhibited better blood coagulation capabilities than LJP-Gel-W, due to their enhanced platelet enrichment and adhesion properties. Consequently, these hydrogels are more conducive to promoting coagulation and have good potential for wound hemostasis.
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Affiliation(s)
| | | | | | - Lijun You
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510640, China
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Yan XH, Ji B, Fang F, Guo XL, Zhao S, Wu ZY. Fast and sensitive smartphone colorimetric detection of whole blood samples on a paper-based analytical device. Talanta 2024; 270:125515. [PMID: 38101035 DOI: 10.1016/j.talanta.2023.125515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 11/25/2023] [Accepted: 12/02/2023] [Indexed: 12/17/2023]
Abstract
BACKGROUND Methods based on paper-based analytical devices (PAD) and smartphone photographic colorimetric detection have become representative instrument-independent point-of-care testing (POCT) platforms due to their low cost and simplicity. However, the detection of target components from whole blood sample still presents challenges in terms of field preparation of small amounts of blood sample and detection sensitivity. This paper presents a rapid online processing method for whole blood samples on PAD based on plasma separation membrane (PSM), and combined with electrokinetic stacking and selective chromatic reaction. Real-time smartphone-based colorimetric detection of free hemoglobin (FHb) and human serum albumin (HSA) was successfully demonstrated. RESULTS With the proposed method, both detections for low and high concentration analytes could be implemented. The limits of detection of 16.6 mg L-1 for FHb and 0.67 g L-1 for HSA were obtained, respectively, with RSD below 8 %. The reliability of the method was verified by the recovery test and desktop spectrophotometric method. The detection results for real blood samples were in agreement with that by clinical methods. SIGNIFICANCE AND NOVELTY The PAD method is inexpensive, simple and fast, and detection of a whole blood sample of 5 μL can be finished in 5 min. This work shows that POCT of biomarkers from whole blood with PAD is possible without using any desktop facilities.
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Affiliation(s)
- Xiang-Hong Yan
- Chemistry Department, College of Sciences, Northeastern University, Shenyang, 110819, China
| | - Bin Ji
- The First Affiliated Hospital of China Medical University, Shenyang, 110001, China
| | - Fang Fang
- Chemistry Department, College of Sciences, Northeastern University, Shenyang, 110819, China
| | - Xiao-Lin Guo
- The First Affiliated Hospital of China Medical University, Shenyang, 110001, China
| | - Shuang Zhao
- Chemistry Department, College of Sciences, Northeastern University, Shenyang, 110819, China.
| | - Zhi-Yong Wu
- Chemistry Department, College of Sciences, Northeastern University, Shenyang, 110819, China.
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Want A, Staniak K, Grabowska-Pyrzewicz W, Fesiuk A, Barczak A, Gabryelewicz T, Kulczyńska-Przybik A, Mroczko B, Wojda U. Optimized RT-qPCR and a novel normalization method for validating circulating miRNA biomarkers in ageing-related diseases. Sci Rep 2023; 13:20869. [PMID: 38012217 PMCID: PMC10682428 DOI: 10.1038/s41598-023-47971-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 11/20/2023] [Indexed: 11/29/2023] Open
Abstract
Circulating miRNAs have potential as minimally invasive biomarkers for diagnosing various diseases, including ageing-related disorders such as Alzheimer's disease (AD). However, the lack of standardization in the common analysis method, RT-qPCR, and specifically in the normalization step, has resulted in inconsistent data across studies, hindering miRNA clinical implementation as well as basic research. To address this issue, this study proposes an optimized protocol for key steps in miRNA profiling, which incorporates absorbance-based haemolysis detection for assessing sample quality, double spike-in controls for miRNA isolation and reverse transcription, and the use of 7 stable normalizers verified in an aging population, including healthy subjects and individuals at different stages of Alzheimer's disease (140 subjects). The stability of these 7 normalizers was demonstrated using our novel method called BestmiRNorm for identifying optimal normalizers. BestmiRNorm, developed utilizing the Python programming language, enables the assessment of up to 11 potential normalizers. The standardized application of this optimized RT-qPCR protocol and the recommended normalizers are crucial for the development of miRNAs as biomarkers for AD and other ageing-related diseases in clinical diagnostics and basic research.
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Affiliation(s)
- Andrew Want
- Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Karolina Staniak
- Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Wioleta Grabowska-Pyrzewicz
- Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Aleksandra Fesiuk
- Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | - Anna Barczak
- Dementia Diseases Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Tomasz Gabryelewicz
- Dementia Diseases Unit, Mossakowski Medical Research Institute, Polish Academy of Sciences, Warsaw, Poland
| | - Agnieszka Kulczyńska-Przybik
- Department of Neurodegeneration Diagnostics, Faculty of Medicine, Medical University of Bialystok, Białystok, Poland
| | - Barbara Mroczko
- Department of Neurodegeneration Diagnostics, Faculty of Medicine, Medical University of Bialystok, Białystok, Poland
| | - Urszula Wojda
- Laboratory of Preclinical Testing of Higher Standard, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.
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Banerjee S, Sarkar S, Saha S, Hira SK, Karmakar S. Observing temporal variation in hemolysis through photoacoustics with a low cost LASER diode based system. Sci Rep 2023; 13:7002. [PMID: 37117171 PMCID: PMC10147907 DOI: 10.1038/s41598-023-32839-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 04/03/2023] [Indexed: 04/30/2023] Open
Abstract
Patients under hemolytic condition need continuous monitoring of lysis as depletion of Red Blood Cells (RBC) and the presence of antioxidant free hemoglobin (Hb) in excess amount due to hemolysis lead to severe deterioration of their health. Out of many modalities, Photoacoustics (PA) offers real time information noninvasively from deep lying blood vessels since Hb is the strongest chromophore in mammalian blood and the PA response of blood varies with the amount of Hb present. During hemolysis, total Hb content in blood however remains unchanged, thus, questions the use of PA in hemolysis detection. In this report, a hypothesis that the amplitude of the PA signal would not change with the amount of lysis is framed and tested by applying osmotic shock to the RBCs in hypotonic environment and the PA response is recorded over time using a low cost NIR based PA system. The experimental outcome indicates that PA amplitude falls off as lysis progresses in course of time consequently rejecting the hypothesis. The decaying PA response also carries the signature of RBC swelling during the early phase of lysis. The PA measurement can detect hemolysis as low as 1.7%. These findings further advocate transforming this NIR-PA system into a portable, noninvasive patient care device to monitor hemolysis in-vivo.
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Affiliation(s)
- Soumyodeep Banerjee
- University Science Instrumentation Centre, The University of Burdwan, Bardhaman, 713104, India
| | - Sandip Sarkar
- Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, Kolkata, 700064, India
| | - Shaibal Saha
- Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, A CI of Homi Bhabha National Institute, Kolkata, 700064, India
| | - Sumit K Hira
- Department of Zoology, The University of Burdwan, Bardhaman, 713104, India
| | - Subhajit Karmakar
- University Science Instrumentation Centre, The University of Burdwan, Bardhaman, 713104, India.
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Head S, Keshavarz Hedayati M. Inverse Design of Distributed Bragg Reflectors Using Deep Learning. Applied Sciences 2022; 12:4877. [DOI: 10.3390/app12104877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Distributed Bragg Reflectors are optical structures capable of manipulating light behaviour, which are formed by stacking layers of thin-film materials. The inverse design of such structures is desirable, but not straightforward using conventional numerical methods. This study explores the application of Deep Learning to the design of a six-layer system, through the implementation of a Tandem Neural Network. The challenge is split into three sections: the generation of training data using the Transfer Matrix method, the design of a Simulation Neural Network (SNN) which maps structural geometry to spectral output, and finally an Inverse Design Neural Network (IDNN) which predicts the geometry required to produce target spectra. The latter enables the designer to develop custom multilayer systems with desired reflection properties. The SNN achieved an average accuracy of 97% across the dataset, with the IDNN achieving 94%. By using this inverse design method, custom-made reflectors can be manufactured in milliseconds, significantly reducing the cost of generating photonic devices and thin-film optics.
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Abstract
Many medical devices such as cardiopulmonary bypass systems, mechanical heart valves, or ventricular assist devices are intended to come into contact with blood flow during use. In vitro hemolysis testing can provide valuable information about the hemocompatibility of prototypes and thus help reduce the number of animal experiments required. Such tests play an important role as research and development tools for objective comparisons of prototypes and devices as well as for the extrapolation of their results to clinical outcomes. Therefore, it is important to explore and provide new ways to improve current practices. In this article, the main challenges of hemolysis testing are described, namely the difficult blood sourcing, the high experimental workload, and the low reproducibility of test results. Several approaches to address the challenges identified are proposed and the respective literature is reviewed. These include the replacement of blood as the "shear-sensitive fluid" by alternative test fluids, the replacement of sparse, manual sampling and blood damage assessment by a continuous and automated monitoring, as well as an analysis of categories and causes of variability in hemolysis test results that may serve as a structural template for future studies.
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Affiliation(s)
- Kai von Petersdorff-Campen
- From the Product Development Group Zurich, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Switzerland
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Naeem N, Drese KS, Paterson L, Kersaudy-Kerhoas M. Current and Emerging Microfluidic-Based Integrated Solutions for Free Hemoglobin and Hemolysis Detection and Measurement. Anal Chem 2021; 94:75-85. [PMID: 34860012 DOI: 10.1021/acs.analchem.1c04567] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Noman Naeem
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Klaus-Stefan Drese
- The Institute of Sensor and Actuator Technology (ISAT), 96450 Coburg, Germany
| | - Lynn Paterson
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Maïwenn Kersaudy-Kerhoas
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.,Infection Medicine, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh EH8 9YL, U.K
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Abstract
A comprehensive review on integrating microfluidic reactors with in situ sensors for reaction probing of chemical transformation.
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Affiliation(s)
- Jun Li
- Institute for Micro Process Engineering (IMVT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Helena Šimek
- Institute of Biological and Chemical Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - David Ilioae
- Gisela and Erwin Sick Laboratory for Micro-optics, Department of Microsystems Engineering, University of Freiburg, Germany
| | - Nicole Jung
- Institute of Biological and Chemical Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Stefan Bräse
- Institute of Biological and Chemical Systems (IBCS-FMS), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Hans Zappe
- Gisela and Erwin Sick Laboratory for Micro-optics, Department of Microsystems Engineering, University of Freiburg, Germany
| | - Roland Dittmeyer
- Institute for Micro Process Engineering (IMVT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Bradley P. Ladewig
- Institute for Micro Process Engineering (IMVT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
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Vishnu J, Manivasagam G. Perspectives on smart stents with sensors: From conventional permanent to novel bioabsorbable smart stent technologies. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/mds3.10116] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jithin Vishnu
- Centre for Biomaterials Cellular and Molecular Theranostics CBCMT Vellore Institute of Technology Vellore India
| | - Geetha Manivasagam
- Centre for Biomaterials Cellular and Molecular Theranostics CBCMT Vellore Institute of Technology Vellore India
- IBTN/In ‐ Indian branch of Institute of Biomaterials Tribocorrosion and Nanomedicine Vellore Institute of Technology Vellore India
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Abstract
Blood damage (hemolysis) can occur during clinical procedures, e.g. dialysis, due to human error or faulty equipment, and it can cause significant harm to the patient or even death. We propose a simple technique to monitor changes in hemolysis levels continuously and in real time. As red blood cells rupture, the overall conductivity of the blood increases. Here, we demonstrate that small changes in porcine blood hemolysis can be detected through a simple resistance measurement.
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Wu T, Chen X, Gong Z, Li Y, Zhang Y. Waveguiding and focusing in a bio-medium with an optofluidic cell chain. Acta Biomater 2020; 103:165-71. [PMID: 31812842 DOI: 10.1016/j.actbio.2019.12.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/28/2019] [Accepted: 12/03/2019] [Indexed: 11/23/2022]
Abstract
Long-distance waveguiding and submicron focusing of light in a bio-medium are crucial for biomedical sensing and imaging. Disordered bio-mediums usually exhibit high scattering and absorption, which limits effective waveguiding and focusing. Here, we demonstrate an optofluidic cell chain, assembled via an optical trapping force from an optical fiber probe, to achieve long-distance waveguiding and submicron light focusing in a disordered bio-medium. By applying a trapping light at 980 nm to generate an optical force, stable binding of E. faecalis cells was achieved in a fluid to assemble cell chains of different lengths. The length could reach up to 360 µm and the incident light (at 675, 532 and 473 nm) could be focused into a beam with a waist radius of 400 nm. As a potential practical application, backscattered signals from human red blood cells were detected using the cell chains, which is expected to benefit biomedical sensing and single cell analysis. STATEMENT OF SIGNIFICANCE: With the assistance of optofluidic techniques, we assembled an E. faecalis cell chain with a length up to 360 µm to achieve long-distance waveguiding and submicron focusing at a propagation loss of 0.03 dB/µm in the bio-medium. Visible lights were launched into the cell chain and the incident lights can converge into a beam with a waist radius of 400 nm. The cell chain was further used to detect the backscattering signals from human red blood cells (RBCs), and the results indicate that the cell chain can be applied as a fully biocompatible extension of the probe for the real-time detection of RBCs in healthy and pathological states.
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Abstract
A challenge for optofluidic absorbance detection is the high concentration limit of detection due to the short optical path length. Herein, we introduce a concept of utilizing the coiled optical nanofiber for highly sensitive and robust optofluidic absorbance detection. Investigated by measuring the absorbance of FeCl3 solutions, the sensor shows a detection limit down to 10 μM with excellent reversibility in a concentration range of 0-5 mM. The sensitivity is 10-fold higher than that of standard absorbance measurement by using a 1 cm cuvette. Also, highly sensitive chloramphenicol sensing was demonstrated by using the enzyme-linked immunosorbent assay (ELISA) method, achieving a detection limit below 0.5 ng/L. The higher sensitivity and lower detection limit are caused by the large fractional power of evanescent field outside the nanofiber and the long detection length, which can effectively improve the absorption of the evanescent field, while the excellent reversibility is caused by the support of a polydimethylsiloxane (PDMS) pillar rather than by suspending the nanofiber in the microchannel. We envision that the present work may open up new opportunities for ultrasensitive chemical and biological sensing.
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Affiliation(s)
- Hongyan Mei
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jing Pan
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Zhang Zhang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Lei Zhang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Limin Tong
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
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Azhar M, Galgalkar S, Chakraborty I, Mehta K, M S R, Prabhu V, Ledden D. Hemolysis Detection in Sub-Microliter Volumes of Blood Plasma. IEEE Trans Biomed Eng 2019; 67:1243-1252. [PMID: 31403404 DOI: 10.1109/tbme.2019.2934517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Hemolysis is one of the main reasons for blood sample rejection in clinical laboratories. The scope of this study is to develop a simple, sensitive, and cost-effective method for hemolysis detection in presence of interferants like bilirubin, and lipids in sub-microliter volumes of blood plasma. METHODS Experimental samples were prepared in plasma extracted from whole blood. These samples were typically mixtures of hemoglobin, bilirubin, and lipids of varying concentrations. A multispectral optical setup was devised to probe these samples without any optical filters or moving parts. RESULTS The hemoglobin content in the samples were measured within the range of 0 mg/dL to 400 mg/dL concentration using <1 μL of detection volume. Detection sensitivity of >90% accuracy and ∼10% coefficient of variation across 27 unknown samples. The optical attenuation path length used was merely ∼150 micrometers. The spectral interference due to overlapping absorption spectrum of bilirubin and scattering spectrum of lipids are resolved using linear matrix algebra algorithms. CONCLUSION Hemolysis can lead to spurious measurements of key clinical parameters such as Potassium, Lactate Dehydrogenase, Aspartic Acid Transferase, and other diagnostic biomarkers. Commonly used visual inspection of blood plasma coloration is prone to variability. Description of the sample preparation, calibration and verification of the experimental setup and linear matrix algebra algorithm for analyte interference determination is reported here. SIGNIFICANCE Owing to the sub-microliter detection volume and high sensitivity, the system has realistic potential to be implemented in point of care medical devices that demands such low volumes of clinical specimen.
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Zhou C, Hedayati MK, Kristensen A. Multifunctional waveguide interferometer sensor: simultaneous detection of refraction and absorption with size-exclusion function. Opt Express 2018; 26:24372-24383. [PMID: 30469557 DOI: 10.1364/oe.26.024372] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/28/2018] [Indexed: 06/09/2023]
Abstract
A waveguide Young interferometer is presented with simultaneous detection of complex refractive index of a liquid sample. The real part of the refractive index change (refraction) is detected by tracing phase shifts of the interferogram generated by a sensing and reference waveguide. The imaginary part of the refractive index (absorption) is determined by the attenuation of the transmitted signal at certain wavelength. Furthermore, nano-filters are fabricated atop the sensing waveguide, which enables size-exclusion filtering of species to the evanescent field. It shows capability of distinguishing small and large particles from 100 nm to 500 nm in diameter, which is further confirmed by fluorescent excitation experiments. The present sensor could find broad application in optical characterization of complex turbid media with regard to their complex refractive index.
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