論文 - 蛭田　勇樹

Small molecule-based alkaline-earth metal ion fluorescent probes for imaging intracellular and intercellular multiple signals

Hiruta Y., Shindo Y., Oka K., Citterio D.

Chemistry Letters （Chemistry Letters）  50 （ 5 ） 870 - 887 2021年05月

研究論文（学術雑誌）, 筆頭著者, 責任著者, 査読有り,  ISSN  03667022

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This highlight review overviews recent progress in fluorescence imaging technology for the alkaline-earth metal ions calcium, and magnesium, by small molecule-based fluorescent probes. Fluorescent probes for Ca2+ using 1,2-bis-(o-aminophenoxy)- ethane-N,N,N′,N′-tetraacetic acid (BAPTA) as a recognition unit are introduced. Focus is set on the fluorescence characteristics and intracellular dynamics of Ca2+ fluorescent probes depending on the differences in fluorophore units. In addition, this review comprehensively covers Mg2+ fluorescent probes from Mg2+ selective ligands and fluorophore units to their application. In particular, the influence of the molecular structure of the fluorescent probes on organelle localization and fluorescence wavelength for imaging intracellular signals in organelles and intercellular multiple signal interactions are summarized, providing a strategy for probe design for chemists, and for selecting the appropriate imaging technique for biologists.

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Long-term single cell bioluminescence imaging with C-3 position protected coelenterazine analogues

Mizui Y., Eguchi M., Tanaka M., Ikeda Y., Yoshimura H., Ozawa T., Citterio D., Hiruta Y.

Organic and Biomolecular Chemistry （Organic and Biomolecular Chemistry）  19 （ 3 ） 579 - 586 2021年01月

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り,  ISSN  14770520

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© The Royal Society of Chemistry 2020. Bioluminescence is a powerful imaging modality for monitoring biological phenomena bothin vitroandin vivo. Bioluminescence imagin (BLI) is becoming a seamless imaging technology covering the range from cells to organs of small animals. Long-term imaging at the single cell level would lead to a true understanding of the dynamics of life phenomena. This work presents a long-term single cell bioluminescence imaging technology accomplished with C-3 position protected furimazines (FMZs), a CTZ analogues, which generate intense blue emission when paired with a highly stable engineered luciferase, Nanoluc. Four types of FMZs protected at the C-3 position have been synthesized. The type and steric bulkiness of the protection group strongly contributed to storage stability and the kinetics of the bioluminescence reactions of the analogues in human living cells. In particular, two developed FMZ analogues resulted in significantly longer bioluminescence emission with higher S/N ratio than FMZ at single cell level. Long-term bioluminescence single cell imaging technology with the developed FMZ analogues will lead to seamless imaging in the range from cells to organs of small animals.

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Anionic fluorophore-assisted fabrication of gold microstructures inside a hydrogel by multi-photon photoreduction

Machida Manan, Shen Weilu, Onoe Hiroaki, Hiruta Yuki, Heisterkamp Alexander, Mazur Eric, Terakawa Mitsuhiro

OPTICAL MATERIALS EXPRESS （Optical Materials Express）  11 （ 1 ） 48 - 58 2021年01月

研究論文（学術雑誌）, 査読有り,  ISSN  2159-3930

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The fabrication of accentuated gold microstructures is demonstrated by multi-photon photoreduction inside an anionic fluorophore-containing hydrogel. We attempted to facilitate gold-ion photoreduction near the focal point of laser pulses, expecting the donation of electrons by the oxidation of fluorophores in the vicinity of gold ions. The presence of anionic FITCdextran also inhibited the spontaneous reduction in untargeted zones, which is attributed to the coordination of gold ions and the anionic FITC-dextran. Simultaneous facilitation and inhibition are promising for the fabrication of dense metal microstructures in the targeted zone while maintaining the hydrogel's light permeability.

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Ion-selective optodes integrated paper-based device for simultaneous colorimetric quantification of salivary Na+, K+ and Ca2+

Suenaga Y., Shibata H., Maejima K., Hiruta Y., Citterio D.

Bunseki Kagaku （Bunseki Kagaku）  70 （ 3 ） 165 - 173 2021年

研究論文（学術雑誌）, 査読有り,  ISSN  05251931

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The quantification of electrolytes in biological fluids plays an important role for evaluating the human health condition. This work proposes a disposable and simple microfluidic paperbased analytical device (µPAD) for the quantitative colorimetric detection of salivary Na+, K+ and Ca2+, relying on ion-selective optodes (ISOs). Nanoscale ISOs composed of pluronic F-127 surfactant-based micelles were used as a colorimetric indicator system, reducing the assay time compared to the previously reported bulk membrane approach. Devices consist of three functionalized paper layers assembled by lamination, with the optical signal read out from the bottom layer. Saliva was chosen as the biological specimen because it is painlessly collected and easy-to-handle, which makes it suitable for POC assays. Simultaneous Na+, K+ and Ca2+ detection by a single µPAD was successfully confirmed by using aqueous metal ion samples with various concentrations of Na+, K+ and Ca2+ within the biologically relevant range. The simultaneous detection of the three cationic species enabled the correction of the three ion quantities by eliminating the interference from other ions using the calculated selectivity coefficients. For proof-of-concept, Na+ quantification in a human saliva sample was conducted by the developed µPADs. The calibration curve for this assay was prepared by applying artificial saliva to the µPADs. The concentrations of Na+ in spiked human saliva were also measured by the µPADs. The obtained recovery rates were 78-132 %, which indicates the quantification of the added Na+ in the real sample matrix. Finally, this µPAD was successfully integrated into a smartphone-based assay, which enables salivary electrolyte quantification in resource poor settings. The developed µPADs satisfy the criteria of low-cost (< $0.3/device), rapidity (< 5 min) and simple analytical procedure compared to the conventional ion-selective electrode (ISE) method.

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Distance readout-based paper device for multiplexed urinalysis

Sawano R., Maejima K., Shibata H., Hiruta Y., Citerrio D.

Bunseki Kagaku （Bunseki Kagaku）  70 （ 3 ） 175 - 181 2021年

研究論文（学術雑誌）, 査読有り,  ISSN  05251931

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Urinalysis is widely used in routine medical checkups. Conventionally, colorimetric paper strips currently available on the market are applied. Although they allow to rapidly obtain results, their use is often not straightforward, because a timed readout is required, followed by comparison with a color chart. D-μPADs (distance-based microfluidic paper-based analytical devices) have gained attention for enabling highly intuitive signal readout. During liquid flow through a paperfluidic channel, target analytes are sequentially depleted from the sample through reaction with colorimetric indicators and/or adsorption to the paper surface, so that the length of color-changed sections correspond to the analyte content. Therefore, D-μPADs are expected to solve the problems of existing urinalysis tests. The final goal is the development of D-μPADs for the simultaneous detection of urinary protein (albumin), glucose and hemoglobin. Colorimetric distance-based calibration curves were acquired for all analytes in artificial urine matrix containing electrolytes and organic compounds. For quantitative assays, evaluation of color-changed distances was conducted by computer software. The first cases of distance-based albumin, glucose and hemoglobin readouts in relatively complex artificial urine matrix are reported. For albumin detection, the color uniformity of the colorimetric indicator was improved by paper surface modification with poly(4-styrenesulfonic acid), an anionic polymer. For glucose detection, signal visibility was significantly improved by paper surface modification with chitosan, a biopolymer that works as immobilization support for enzymes. Finally, we evaluated the effect of urinary components on the assay results. It was confirmed that D-μPADs for the hemoglobin assay require a treatment to reduce the effect of albumin adsorption on the paper substrate.

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Fluorescent and Bioluminescent Probes based on Precise Molecular Design

Kumada Rei, Orioka Mariko, Citterio Daniel, Hiruta Yuki

BUNSEKI KAGAKU （Bunseki Kagaku）  70 （ 10-11 ） 600 - 616 2021年

研究論文（学術雑誌）, 最終著者, 責任著者, 査読有り,  ISSN  0525-1931

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Fluorescence and bioluminescence have been actively applied to various chemical sensors and biosensors, including to cellular/in vivo imaging. On application to the detection of specific targets, it is necessary to develop fluorescent/bioluminescent probes that selectively respond to the target analytes such as molecules, ions or cells by changing their optical properties. The authors have focused on the development of small molecular probes by means of molecular design based on the desired function. In this paper, we describe the approaches to molecular design of fluorescent/bioluminescent probes and their applications, including the introduction of our recent research works. Finally, a future outlook for further functionalization of small molecular probes is provided.

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Near-infrared pH responsive heptamethine cyanine platforms: Modulating the proton acceptor

Kurutos A., Shindo Y., Hiruta Y., Oka K., Citterio D.

Dyes and Pigments （Dyes and Pigments）  181 2020年10月

研究論文（学術雑誌）, 査読有り,  ISSN  01437208

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© 2020 Elsevier Ltd In this report, we wish to present the rational design, synthesis, and study of optical characteristics of near-infrared (NIR) molecular probes emitting over 800 nm. The title pH sensing platforms consist of a piperazine moiety serving as a hydronium ion receptor, coupled with a rigidified symmetric heptamethine backbone. The spectrally fine-tuned response of the fluorophores was studied in both organic solvents and aqueous buffer solutions, employing combined UV–Vis and steady state fluorimetric techniques. In parallel, computational approach and optical spectroscopy were employed aiming to ascribe the origin of spectral behavior of the amino-substituted heptamethines. Herein, we also investigated the halochromic effect of the differently substituted piperazines on the spectral properties of the NIR cyanine dyes. Under acidic conditions, the protonation of the piperazine moiety promoted a gradual bathochromic shift in the absorption spectra. The Δλ between the neutral and the protonated forms are indirectly related to the modifications applied to the proton acceptor. The calculated pKa values (5.13–7.06) were found to be dependent on the dye chemical structure. A good linear correlation was established between the pKa of the newly synthesized dyes and that of the reported piperazine moieties. This aspect allows the future expansion of the current facile strategy since sensing chromophores with predicted pH response could readily be designed based on pKa databases for substituted piperazine derivatives. A detailed literature study along with NMR and computational methods were found to be in agreement with our assumption, that both nitrogen atoms of the 1,4-disubstituted amine are involved in the sensing process. The covered pKa range allows us to recommend the title fluorophores as promising potential candidates for qualitative analysis of biological samples. A cytotoxicity study by the MTT assay showed that the NIR dyes are safe and applicable for bioanalytical purposes at dye concentrations up to 10 μM. Fluorescence imaging and cellular applications, including staining and visualization of HeLa cervical cancer cells was successfully demonstrated.

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All-printed semiquantitative paper-based analytical devices relying on QR code array readout

Katoh A., Maejima K., Hiruta Y., Citterio D.

The Analyst （The Analyst）  145 （ 18 ） 6071 - 6078 2020年09月

研究論文（学術雑誌）, 査読有り,  ISSN  0003-2654

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The wide spread of smartphones and QR codes for various end-user applications has had an impact beyond traditional fields of use, recently also reaching point-of-care testing (POCT). This work presents the integration of QR code recognition into paper-based analytical devices (PADs) with "distance-based" colorimetric signalling, resulting in semiquantitative readout fully relying on straightforward barcode reader solutions. PADs consist of an array of QR codes arranged in series inside a paperfluidic channel. A mask dye concept has been developed, which enables utilisation of colour changing indicators by initially hiding QR codes. The colour change of the indicator induced by the presence of an analyte of interest results in gradual unmasking of QR codes, which become recognisable by the smartphone barcode reader app. To reproducibly fabricate devices, all fabrication steps were performed by commercial desktop solid ink and inkjet printing. The QR code masking function was optimised by controlling the amount of printed mask dye through adjusting the opacity of printing patterns during the inkjet deposition process. For proof-of-concept, a model assay in the form of colorimetric copper ion (Cu2+) detection in the concentration range of 0.4 mM to 3.2 mM was evaluated. Consistent results independent of the smartphone model and environmental light condition were achieved with a free barcode reader app. To the best of our knowledge, this work is the first demonstration of a semiquantitative assay approach fully relying on QR code readout without digital colour analysis, customised app or hardware modification.

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Text-Displaying Semiquantitative Competitive Lateral Flow Immunoassay Relying on Inkjet-Printed Patterns

Misawa K., Yamamoto T., Hiruta Y., Yamazaki H., Citterio D.

ACS Sensors （ACS Sensors）  5 （ 7 ） 2076 - 2085 2020年07月

研究論文（学術雑誌）, 査読有り,  ISSN  2379-3694

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Copyright © 2020 American Chemical Society. This work describes a colorimetric signaling approach for competitive lateral flow immunoassays (LFIAs) enabling sensitive and semiquantitative direct visual result readout in the form of "text", demonstrated on the example of 8-hydroxy-2′-deoxyguanosine (8-OHdG) detection. The distinctive feature of the developed text-displaying LFIA (TD-LFIA) is the test zone system consisting of a combination of two types of inkjet-deposited capture molecules referred to as "mask antigen"and "text antibody", allowing for sensitive turn-on signaling as opposed to the inverse response of conventional competitive LFIAs. The user operation is limited to sample application, followed by direct reading of assay results written in text after approximately 10 min. TD-LFIAs enabled the visual detection of 8-OHdG at concentrations down to 3 ng/mL, which is a 2-3 orders of magnitude lower visual detection limit than that achieved with the corresponding conventional design and is comparable to the existing LFIAs relying on external signal readout equipment. Highly reproducible observer-independent assay performance was confirmed, and the result interpretation is not influenced by sample color and readout timing. Making use of customizable threshold settings for text appearance, a device for semiquantitative assays was developed and successfully applied to the detection of 8-OHdG at four concentration levels (trace, low, medium, and high) in 54 human urine samples within the clinically relevant concentration range. The sensitive and intuitive signaling method of the developed system offers great potential for an alternative competitive LFIA platform suitable for real-world point-of-care testing applications.

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Thread-Based Bioluminescent Sensor for Detecting Multiple Antibodies in a Single Drop of Whole Blood

Tomimuro K., Tenda K., Ni Y., Hiruta Y., Merkx M., Citterio D.

ACS Sensors （ACS Sensors）  5 （ 6 ） 1786 - 1794 2020年06月

研究論文（学術雑誌）, 査読有り,  ISSN  2379-3694

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Copyright © 2020 American Chemical Society. Antibodies are important biomarkers in clinical diagnostics in addition to being increasingly used for therapeutic purposes. Although numerous methods for their detection and quantification exist, they predominantly require benchtop instruments operated by specialists. To enable the detection of antibodies at point-of-care (POC), the development of simple and rapid assay methods independent of laboratory equipment is of high relevance. In this study, we demonstrate microfluidic thread-based analytical devices (μTADs) as a new platform for antibody detection by means of bioluminescence resonance energy-transfer (BRET) switching sensor proteins. The devices consist of vertically assembled layers including a blood separation membrane and a plastic film with a sewn-in cotton thread, onto which the BRET sensor proteins together with the substrate furimazine have been predeposited. In contrast to intensity-based signaling, the BRET mechanism enables time-independent, ratiometric readout of bioluminescence signals with a digital camera in a darkroom or a smartphone camera with a 3D-printed lens adapter. The device design allows spatially separated deposition of multiple bioluminescent proteins on a single sewn thread, enabling quantification of multiple antibodies in 5 μL of whole blood within 5 min. The bioluminescence response is independent of the applied sample volume within the range of 5-15 μL. Therefore, μTADs in combination with BRET-based sensor proteins represent user-friendly analytical tools for POC quantification of antibodies without any laboratory equipment in a finger prick (5 μL) of whole blood.

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Metal-Free Colorimetric Detection of Pyrophosphate Ions by Inhibitive Nanozymatic Carbon Dots

Chen C.Y., Tan Y.Z., Hsieh P.H., Wang C.M., Shibata H., Maejima K., Wang T.Y., Hiruta Y., Citterio D., Liao W.S.

ACS sensors （ACS sensors）  5 （ 5 ） 1314 - 1324 2020年05月

研究論文（学術雑誌）, 査読有り,  ISSN  2379-3694

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The pyrophosphate ion (P2O74-, PPi) plays a critical role in various biological processes and acts as an essential indicator for physiological mechanism investigations and disease control monitoring. However, most of the currently available approaches for PPi species detection for practical usage still lack appropriate indicator generation, straightforward detection requirements, and operation convenience. In this study, a highly sensitive and selective PPi detection approach via the use of nanozymatic carbon dots (CDs) is introduced. This strategy eliminates the common need for metal ions in the detection process, where a direct indicator-PPi interaction is adopted to provide straightforward signal reports, and importantly, through a green indicator preparation. The preparation of this nanozymatic CDs' indicator utilizes an aqueous solution refluxing, employing galactose and histidine as the precursor materials. The mild conditions of the solution refluxing produce fluorescent CDs exhibiting peroxidase-mimic properties, which can catalyze the o-phenylenediamine oxidation under the presence of H2O2. The introduction of PPi species, interestingly, inhibits this process very efficiently, the extent of which can be colorimetrically monitored by the generated yellow product 2,3-diaminophenazine. Spectroscopic results point to CD surface functional groups' selective binding toward PPi species, which severely interferes with the electron transfer process in the enzymatic catalysis. Relying on this CD peroxidase-mimetic property inhibition, sensitive and selective recognition of PPi reaches a detection limit of 4.29 nM, enabling practical usage in complex matrixes. Owing to the superior compatibility and high stability of nanozymatic CDs, they can also be inkjet-printed on paper-based devices to create a portable and convenient platform for PPi detection. Both the solution and the paper-device-based selective recognitions confirm this unique and robust metal-free inhibitive PPi detection, which is supported by a convenient green preparation of nanozymatic CDs.

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Quantitative evaluation of luminescence intensity from enzymatic luminescence reaction of coelenterazine and analogues

Ikeda Y., Tanaka M., Nishihara R., Hiruta Y., Citterio D., Suzuki K., Niwa K.

Journal of Photochemistry and Photobiology A: Chemistry （Journal of Photochemistry and Photobiology A: Chemistry）  394 2020年05月

研究論文（学術雑誌）, 査読有り,  ISSN  10106030

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© 2020 Elsevier B.V. Recent advances in bioluminescence technology rely on the discovery of luciferin-luciferase pairs having excellent luminescence activity. Here, we focus on coelenterazine (CTZ) and its analogues and quantitatively investigate reaction factors, including bioluminescence reaction quantum yield (φBL) and enzyme reaction kinetics (turnover rate, kcat), determining the luminescence intensity to design brighter reaction systems. Initially, it was confirmed that the CTZ was kept stable during the storage and the φBL value measuring experiment in terms of comparative study using benzyl-protected CTZ. Using a luminometer whose absolute responsivity is calibrated for each luminescence reaction spectrum, we absolutely measured φBL and other reaction factors of CTZ and 3 types of blue-shifted CTZ analogues, CTZ 400a, 6-pi-H-CTZ and 6-pi-Ph-CTZ. The results suggested that there was no significant difference in reaction kinetics, but a clear difference in φBL (up to 22-fold), which was presumably due to an improvement in fluorescence quantum yield (φFL) of the corresponding coelenteramide (CTMD), oxidized form of CTZ. Our evaluation suggests that the design of CTZ analogues considering φFL is important for developing a bright luminescent reaction system.

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Paper-Based Device for Naked Eye Urinary Albumin/Creatinine Ratio Evaluation

Hiraoka R., Kuwahara K., Wen Y.C., Yen T.H., Hiruta Y., Cheng C.M., Citterio D.

ACS Sensors （ACS Sensors）  5 （ 4 ） 1110 - 1118 2020年04月

研究論文（学術雑誌）, 査読有り,  ISSN  2379-3694

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Copyright © 2020 American Chemical Society. This paper introduces the concept of "Drawing-PADs" (Drawing paper-based microfluidic analytical devices) allowing to intuitively evaluate the urinary albumin (Alb) index, a clinically important parameter used for the early detection of renal deficiencies related to diabetes, among others. To enable regular monitoring of the Alb index, a simple examination method suitable for self-diagnosis is highly desirable. The Drawing-PADs rely on the simultaneous naked eye detection of Alb and creatinine (Cre) on a single device according to the distance-based microfluidic PAD (μPAD) approach. The Alb index is visualized by simply drawing a straight line connecting the top of two color-changed assay channel sections (Alb and Cre channels), followed by visually confirming the position of the intercept of the drawn straight line. The semiquantitative Alb index evaluation performed with Drawing-PADs does not require any equipment such as a camera, software, or a color reference chart. The obtained results are independent of the sample volume and are not influenced by changes in the absolute Alb and Cre concentrations caused by urine excretion variations, making spot urine assays possible. Classification of Alb index values according to clinically relevant criteria (normoalbuminuria, microalbuminuria, and macroalbuminuria) is readily achieved within 15 min and has been validated for 15 human urine samples including diabetic patients and healthy volunteers.

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Centrifugal Paperfluidic Platform for Accelerated Distance-Based Colorimetric Signal Readout

Maejima Kento, Hiruta Yuki, Citterio Daniel

ANALYTICAL CHEMISTRY （Analytical Chemistry）  92 （ 7 ） 4749 - 4754 2020年04月

研究論文（学術雑誌）, 査読有り,  ISSN  0003-2700

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Copyright © 2020 American Chemical Society. Distance-based readout is one of the most user-friendly and simple colorimetric signaling methods widely applied for paper-based analytical devices (PADs). This work presents the integration of distance readout PADs into a centrifugal platform enabling affordable, rapid, and sample volume-independent colorimetric assays. Centrifugally assisted distance-based PADs (CD-PADs) eliminate the requirement to use micropipets for sample introduction and reduce the overall time for distance-based assays. All device fabrication steps were performed through computer-controlled print, cut, and laminate (PCL) techniques oriented toward mass production. The inexpensive centrifugal platform was built on a recycled DVD player combined with an open source microcomputer (Arduino). Assay protocols, including rotational velocity and rotation time, were optimized to obtain a maximum dynamic range and reproducible results for sample volume metering (coefficient of variation 3.62%). A colorimetric Ni2+ assay chosen to demonstrate measurements on CD-PADs allowed the detection of nickel ions (Ni2+) with naked-eye interpretation within 1.5 min and a limit of detection (LOD) of 44.1 ng of Ni2+, which to the best of our knowledge is the lowest value reported for a distance-based Ni2+ assay.

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pH-Responsive Tunable Mixed-Charge Polymers for pH-Selective Interaction with Anionic Biological Constituents

Hiruta Yuki, Sawada Kazuki, Mizui Yuki, Citterio Daniel

BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN （Bulletin of the Chemical Society of Japan）  93 （ 4 ） 547 - 552 2020年04月

研究論文（学術雑誌）, 筆頭著者, 責任著者, 査読有り,  ISSN  0009-2673

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A pH-responsive mixed-charge polymer consists of uniformly distributed cationic and anionic units in the polymer chain. Carboxylic acid monomers are generally used as anionic monomers. The pH responsive range is confined to a relatively narrow pH of Â5, which is limiting the biological application of pH-responsive polymers. Therefore, we investigated the effect of a series of carboxylic acid and neutral monomers on the pKa value of pH-responsive mixed-charge polymers. We synthesized the polymers using [2-(methacryloyloxy)ethyl]-trimethylammonium chloride, carboxylic acid monomers, and neutral monomers as the spacer moiety. As the monomer hydrophobicity and the composition ratio of neutral monomers increased, the pKa shifted to higher values. Finally, the polymer pKa values were tuned from 4.6 to 6.1. We confirmed that the pH-dependent interaction between anionic tissue constituent and pH-responsive mixed-charge polymers depends on their pKa.

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Ring-Fused Firefly Luciferins: Expanded Palette of Near-Infrared Emitting Bioluminescent Substrates

Ikeda Y., Nomoto T., Hiruta Y., Nishiyama N., Citterio D.

Analytical chemistry （Analytical chemistry）  92 （ 6 ） 4235 - 4243 2020年03月

研究論文（学術雑誌）, 査読有り,  ISSN  00032700

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Firefly bioluminescence is broadly applied as a noninvasive imaging modality in the biomedical research field. One limitation in firefly bioluminescence imaging is the limited variety of luciferins emitting in the near-infrared (NIR) region (650-900 nm), where tissue penetration is high. Herein, we describe a series of structure-inherent NIR emitting firefly luciferin analogues, NIRLucs, designed through a ring fusion strategy. This strategy resulted in pH-independent structure-inherent NIR emission with a native firefly luciferase, which was theoretically supported by quantum chemical calculations of the oxidized form of each luciferin. When applied to cells, NIRLucs displayed dose-independent improved NIR emission even at low concentrations where the native d-luciferin substrate does not emit. Additionally, excellent blood retention and brighter photon flux (7-fold overall, 16-fold in the NIR spectral range) than in the case of d-luciferin have been observed with one of the NIRLucs in mice bearing subcutaneous tumors. We believe that these synthetic luciferins provide a solution to the longstanding limitation in the variety of NIR emitting luciferins and pave the way to the further development of NIR bioluminescence imaging platforms.

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Traffic-light-type microfluidic paper-based analytical device for hydrogen peroxide detection

Ohta S., Hiraoka R., Hiruta Y., Citterio D.

MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences （MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences）     444 - 445 2020年

　概要を見る

© 2020 CBMS-0001 This work reports an intuitive signaling approach enabling naked-eye semi-quantitative result readout in the form of a “traffic-light” for microfluidic paper-based analytical devices (µPADs). The detection of hydrogen peroxide has been demonstrated with the aim of quantifying metabolites relevant as biomarkers of various lifestyle-related diseases. User operation is limited to simple sample application, followed by observing the traffic-light signal after approximately 10 min. Due to its intuitiveness with very low probability of result misinterpretation, this system is expected to offer great potential for home-based self-diagnostic point-of-care testing (POCT) applications.

Ink-jet printed microfluidic paper-based analytical devices relying on QR code detection

Katoh A., Maejima K., Hiruta Y., Citterio D.

MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences （MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences）     456 - 457 2020年

　概要を見る

© 2020 CBMS-0001 Microfluidic paper-based analytical devices (µPADs) that display semi-quantitative analysis results by reading a QR code have been developed. The only user operation required is to apply the sample and to read the displayed QR code with a mobile device to obtain the result. Copper ions were detected as a model target and the copper ion concentration-dependent display of QR codes was achieved. This simple assay method can be applied to other targets and has great potential for point-of-care testing (POCT) applications.

Cellophane-based analytical devices for pump-free liquid transport and background-tinted colorimetric assays

Shigemori H., Maejima K., Shibata H., Hiruta Y., Citterio D.

MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences （MicroTAS 2020 - 24th International Conference on Miniaturized Systems for Chemistry and Life Sciences）     422 - 423 2020年

　概要を見る

© 2020 CBMS-0001 This report suggests utilizing “cellophane” as a new substrate material for point-of-care testing (POCT) devices. Cellophane-based microfluidic devices were fabricated by a print, cut and lamination (PCL) methodology and sample liquid was transported into four assay areas without external pumping. Furthermore, making use of the transparency of cellophane, background-tinted devices were fabricated. Based on a blue background-tinted cellophane device, the dynamic range of a hue-based H2O2 assay was 46-fold increased compared to performing the same assay on a white background device. Finally, turbidity testing for albumin was implemented on black background-tinted devices with a visual detection limit of 15 mg/dL.

Fabrication and application of microfluidic paper-based analytical devices (μPAD)

Shigemori H., Hiruta Y., Citterio D.

Kinoshi Kenkyu Kaishi/Annals of the High Performance Paper Society, Japan （Kinoshi Kenkyu Kaishi/Annals of the High Performance Paper Society, Japan）  59   17 - 23 2020年

ISSN  02885867

　概要を見る

Bio)chemical sensors based on paper substrates show attractive features such as being low cost, portable and disposable. Therefore, the technology is currently used in urinary dipsticks and immunochromatographic test strip. In recent years, many research groups report studies on microfluidic paper-based analytical devices (μPADs). In spite of the simplicity of paper-based platforms, μPADs enable performing complicated analytical procedures, multiplex target analysis and equipment-free detection. Due to these useful functions, μPADs are paid attention for point-of-care testing (POCT) and for field-deployable analysis. Herein, we introduce the fabrication methodology and clinical applications of μPADs developed by our research group.

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