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In this work, we report the first demonstration of chemiluminescence (CL) detection for microfluidic cloth-based analytical devices (μCADs). Wax screen-printing is used to make cloth channels or chambers, and enzyme-catalyzed CL reactions are imaged using an inexpensive charge coupled device (CCD). We first evaluate the relationship between the wicking rate and the length/width of cloth channel. For our device, the channel length and width between the loading and detection chambers are optimized to be 10 mm and 3 mm. Thus, the detection procedure can be accomplished in about 15 s on a cloth-based device (15×30 mm 2 ) by using 25-μL sample spotted on it. Next, several parameters affecting cloth-based CL intensity are studied, including exposure time, pH, and concentrations of luminol and enzyme. Under optimal conditions, a linear relationship is obtained between CL intensity and hydrogen peroxide (H 2 O 2 ) concentrations in the range of 0.5–5 mM with a detection limit of 0.46 mM. Finally, the utility of cloth-based CL is demonstrated for determination of H 2 O 2 residues in meat samples. On our device, the chicken meat soaked for 6 h with 3% H 2 O 2 can be detected. Moreover, the supernatant of grinded meat sample can be directly applied, without need for other treatments. We believe that μCADs with CL detection could provide a new platform of rapid and low-cost assays for use in areas such as food detection and environmental monitoring. [ABSTRACT FROM AUTHOR]

Colorimetric lateral flow immunoassay (LFIA) is a widely used point-of-care testing (POCT) technology, while it has entered a bottleneck period because of low detection sensitivity, expensive preparation materials, and incapable quantitative detection. Therefore, it is necessary to develop a novel POCT method that is ultrasensitive, simple, portable, and capable of accurately detecting biomarkers in biofluids daily, particularly for pregnancy preparation and early screening of diseases. In this work, a novel dry chemistry-based self-enhanced electrochemiluminescence (DC-SE-ECL) LFIA sensor is introduced for accurate POCT of luteinizing hormone (LH). The proposed DC-SE-ECL immunosensor significantly improves the detection sensitivity through the Poly- l -Lysine (PLL)-based SE-ECL probe and cathode modification of closed bipolar electrode (C-BPE). Additionally, a new type of C-BPE configuration is designed for easily performing the LFIA. And, two standalone absorbent pads are symmetrically arranged below the reporting channel of the electrode pad to decease useless residues on the detection pad, which further improves the detection performance. Under optimized conditions, the proposed LFIA sensor has a low limit of detection (9.274 μIU mL−1) and a wide linear dynamic range (0.01–100 mIU mL−1), together with good selectivity, repeatability and storage stability. These results indicate that the proposed DC-SE-ECL method has the potential as a new tool for detecting biomarkers in clinical samples. [Display omitted] • A novel DC-SE-ECL LFIA sensor was applied for detection of LH. • The sensitivity was greatly improved through the SE-ECL probe and cathode modification. • The LFIA strip was easily fabricated by using various cloth materials. • The portable ECL analyzer was used for rapid immunodetection (about 6 min). • The detection limit was 9.274 μIU mL −1, and the linear range was from 0.01 to 100 mIU mL−1. [ABSTRACT FROM AUTHOR]

In this work, a solely gravity and capillary force-driven flow chemiluminescence (GCF-CL) paper-based microfluidic device has been proved for the first time as a new platform for inexpensive, usable, minimally-instrumented dynamic chemiluminescence (CL) detection of chromium (III) [Cr(III)], where an appropriate angle of inclination between the loading and detection zones on the paper produces a rapid flow of CL prompt solution through the paper channel. For this study, we use a cost-effective paper device that is manufactured by a simple wax screen-printing method, while the signal generated from the Cr(III)-catalyzed oxidation of luminol by H2O2 is recorded by a low-cost and luggable CCD camera. A series of GCF-CL affecting factors have been evaluated carefully. At optimal conditions, two linear relationships between GCF-CL intensities and the logarithms of Cr(III) concentrations are obtained in the concentration ranges of 0.025–35 mg/L and 50–500 mg/L separately, with the detection limit of 0.0245 mg/L for a less than 30 s assay, and relative standard deviations (RSDs) of 3.8%, 4.5% and 2.3% for 0.75, 5 and 50 mg/L of Cr(III) (n = 8). The above results indicate that the GCF-CL paper-based microfluidic device possesses a receivable sensitivity, dynamic range, storage stability and reproducibility. Finally, the developed GCF-CL is utilized for Cr(III) detection in real water samples. [ABSTRACT FROM AUTHOR]

Luteinizing hormone (LH) is a gonadotropin, and its concentration is closely related to the female ovulation cycle. However, the traditional lateral flow method for LH detection has poor sensitivity and sustainability. In this work, a dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor (μFIS) has been firstly proposed for electrochemiluminescence (ECL) point-of-care testing (POCT) of LH. The μFIS was composed of four-layer fiber material (paper and cloth)-based pads, and was combined with closed bipolar electrode-ECL (CBPE-ECL) to quantitatively detect LH. The CBPE-ECL μFIS not only retained the high sensitivity and wide linear range associated with CBPE-ECL, but also reserved the simplicity and practicality of the lateral flow assay. In addition, a self-enhanced intramolecular ECL probe was incorporated into the μFIS for signal amplification. Under optimized conditions, the μFIS had a very low detection limit (0.125 μIU mL-1) and positive linear relationship (0.001–100 mIU mL-1), together with excellent selectivity, reproducibility and storage stability. Moreover, the CBPE-ECL μFIS was applied to detect LH in human clinical serum samples, and the results had a good correlation with those of clinical samples. These results revealed that the CBPE-CEL μFIS had the potential as a high-performance POCT for LH or other biomarkers. [Display omitted] • A novel dry chemistry-based ECL immuosensor was applied for detection of LH. • The self-enhanced Ru(II)-PLL complex was applied for ultrasensitive detection. • The microfluidic chip was easily fabricated with cloth and filter paper. • The automatic portable ECL analyzer was used for rapid detection (about 8 min). • The detection limit was 0.125 μIU mL-1, and the linear range is from 0.001 to100 mIU mL-1. [ABSTRACT FROM AUTHOR]

As one of the most common noninfectious diseases, diabetes and diabetic complications (DDC) have attracted great attention in the field of life and health. However, simultaneous detection of DDC markers usually requires labor- and time-consuming steps. Here, a novel cloth-based single-working-electrode electrochemiluminescence (SWE-ECL) sensor was designed for the simultaneous detection of multiple DDC markers. For this sensor, three independent ECL cells are distributed on the SWE, which is a simplification of the configuration of traditional sensors for simultaneous detection. In this way, the modification processes and ECL reactions occur at the back of the SWE, eliminating the adverse effects caused by human intervention on the electrode. Under optimized conditions, glucose, uric acid and lactate were determined, with corresponding linear dynamic ranges of 80–4000 μM, 45–1200 μM and 60–2000 μM, and detection limits of 54.79 μM, 23.95 μM and 25.82 μM, respectively. In addition, the cloth-based SWE-ECL sensor exhibited good specificity and satisfactory reproducibility, and its actual application potential was verified by measuring complex human serum samples. Overall, this work developed a simple, sensitive, low-cost and rapid method for the simultaneous quantitative determination of multiple markers related to DDC and demonstrated a new route for multiple-marker detection. [Display omitted] • A cloth-based SWE-ECL sensor is reported for the first time. • The sensor is proposed to detect multiple diabetes and diabetic complications markers. • The simultaneous ECL determination of three markers only uses one SWE. • The modification processes and ECL reactions occur at the back of the SWE. • The sensor is simple, cost-effective, portable and environmentally friendly. [ABSTRACT FROM AUTHOR]

In this work, we firstly report a novel battery-triggered open wireless electrochemiluminescence (O-WL-ECL) sensing strategy based on the microfluidic cloth-based bipolar devices (μCBPDs). The carbon ink-screen-printing is used to fabricate the bipolar electrodes (BPEs) and driving electrodes on the cloth which is patterned with wax-screen-printed hydrophilic channels to create low-cost sensors ($0.011 per device) which can be powered with a rechargeable battery and read with an inexpensive, portable charge coupled device (CCD) camera. Moreover, the widely-used luminol/hydrogen peroxide (H 2 O 2 ) ECL reaction has been performed to illustrate the quantitative ability of the O-WL-ECL μCBPDs. Under optimized conditions, the μCBPDs can achieve the measurement of H 2 O 2 , with a linear range of 0.025–10 mM and a detection limit of 0.024 mM. Additionally, the determination of glucose can be carried out in the linear range from 0.025 mM to 10 mM, with a detection limit of 0.023 mM. It has been shown that the O-WL-ECL on μCBPDs has an acceptable sensitivity, stability and reproducibility. Finally, this simple and cost-effective device is successfully applied for the measurements of H 2 O 2 in milk and glucose in clinical urine and serum samples. Therefore, the proposed methodology could provide great promise in applications in many areas, and may facilitate the achievement of point-of-care testing. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence (ECL) chips have been widely used in the field of medical diagnosis. However, most of these chips currently in use are costly and require high amounts of sample. In this work, we present, for the first time, a shared-cathode closed bipolar electrochemiluminescence (SC-CBP-ECL) cloth-based chip, which can be used for multiplex detection. The SC-CBP-ECL chips ($0.03–0.05 for each chip) are manufactured using carbon ink- and wax-based screen-printing techniques, without the need for expensive and complex fabrication equipment. Under optimised conditions, the SC-CBP-ECL chips were successfully used for coinstantaneous detection of glucose in double ECL systems (i.e., Ru(bpy) 3 2+ and luminol), with corresponding linear ranges of 0.05–1 mM and 0.05–10 mM, and detection limits of 0.0382 mM and 0.0422 mM. To our knowledge, this is the first report on the application of fibre material-based closed bipolar electrodes (C-BPE) combined with double ECL systems. Furthermore, the SC-CBP-ECL chips exhibit an acceptable specificity and good reproducibility and stability and can be used for glucose detection in human serum samples with a good agreement compared with the clinical method. Finally, the SC-CBP-ECL chips could be successfully used for simultaneous detection of seven glucose samples and also show potential for simultaneous detection of three different targets (hydrogen peroxide [H 2 O 2 ], glucose, and uric acid [UA]). Therefore, we believe that the chip described in this study has broad potential application in the field of cost-effective multiplex detection. [Display omitted] • A shared-cathode closed bipolar electrochemiluminescence (SC-CBP-ECL) is reported. • The combination of cloth-based C-BPE and double ECL system is presented. • The SC-CBP-ECL can be used for coinstantaneous detection of seven glucose samples. • The SC-CBP-ECL can be applied for simultaneous detection of three different targets. • The proposed multiplex detection method is cost-effective. [ABSTRACT FROM AUTHOR]

This study involved the construction of a novel cloth-based CBP-SS-ECL aptasensor by introducing proximity hybridisation (PH) and solid-state electrochemiluminescence (SS-ECL) into a closed bipolar (CBP) electrochemistry system. Screen-printing was used to fabricate the cloth-based aptasensors, and PH and aptamers provided good selectivity for the sensor. Furthermore, the CBP-SS-ECL sensing interface was produced by immobilising of Ru(bpy) 3 2+- doped silica nanoparticles (Ru–Si-NPs) on the anode of closed bipolar electrode (C-BPE). PH product (PP) was formed due to the target (carcinoembryonic antigen, CEA), and then the PP opened the Au NP-labelled capture probe (Au-CP) on the C-BPE anode (CBA), allowing ferrocene carboxylic acid (FcA) close to the CBA surface and Au NPs away from the surface. The corresponding quenching and enhancement of ECL signal by FcA and Au NPs, respectively, markedly enhanced ECL signal. This aptasensor successfully achieved quantitative detection of CEA, with a linear detection range of 5–100000 pg mL−1 and a detection limit of 1.6 pg mL−1. The described aptasensor showed an acceptable sensitivity, selectivity, stability, and ability to detect CEA levels in complex human serum samples. In particular, this aptasensor showed satisfactory versatility, indicating its potential for simultaneous detection of CEA and K-ras gene. [Display omitted] • A cloth-based CBP-SS-ECL aptasensor is firstly proposed. • The SS-ECL is constructed by immobilising Ru(bpy) 3 2+ doped Si-NPs on the electrode. • Ferrocene carboxylic acid (FcA) and Au NPs are coupled to improve the sensitivity. • The CEA levels in complex human serum samples can be measured. • The universal and simultaneous detection of different targets can be achieved. [ABSTRACT FROM AUTHOR]

• A cloth-based microfluidic proximity hybridization-electrochemiluminescence (PH-ECL) DNA biosensor is firstly proposed. • The "H"-shaped complexes increase the sensitivity and selectivity of label-free PH-ECL biosensor. • The multi-walled carbon nanotubes-chitosan can be well used for electrode modification to further improve the sensitivity. • The K-ras gene levels in complex human serum samples can be measured. • The universal determination of different DNA targets can be well achieved. In this work, we firstly propose a cloth-based microfluidic DNA biosensor capable of label-free proximity hybridization-electrochemiluminescence (PH-ECL) detection of target DNA (T-DNA). Carbon ink screen-printing is applied to make the cloth-based electrodes that are patterned with wax-screen-printed cloth-based chambers to fabricate a foldable three-dimensional (3-D) cloth-based device for facile fabrication of multi-walled carbon nanotubes (MWCNTs)-modified PH-ECL sensing interface. When the PH complexes (PC) formed by the T-DNA and help DNA sequences (H-DNA1 and H-DNA2), together with Ru(bpy) 3 2+ (TBR) molecules, are applied onto such a sensing interface, the TBR/tripropylamine (TPA)-based PH-ECL can be well triggered. Under optimized conditions, the biosensor has successfully fulfilled the label-free detection of K-ras gene in the linear range of 0.001–2500 pM, with a detection limit of 0.13 fM. The emission of PH-ECL on the cloth-based device exhibits a relatively high sensitivity, specificity, reproducibility and stability, possibly due to the good formation of "H"-shaped complexes on the electrode. Especially, the biosensor has the ability for K-ras gene detection in complex human serum samples, identification of single-base-mismatched and even two-base-mismatched K-ras gene targets, and universal determination of different T-DNA samples. Thus, it may become a promising avenue for gene diagnostics with wide applications. [ABSTRACT FROM AUTHOR]