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A portable and universal upconversion nanoparticle-based lateral flow assay platform for point-of-care testing
摘要： Upconversion nanoparticle-based lateral flow assays (UCNP-LFAs) have attracted significant attention in point-of-care testing (POCT) applications, due to the long-term photostability and enhanced signal-to-background noise ratio. The existing UCNP-LFAs generally require peripheral equipment for exciting fluorescent signals and reading out fluorescence results, which are generally bulky and expensive. Herein, we developed a miniaturized and portable UCNP-LFA platform, which is composed of a LFA detection system, an UCNP-LFA reader and a smartphone-assisted UCNP-LFA analyzer. The LFA detection system is based on three types of UCNPs for multiplexed detection. The reader has a dimension of 24.0 cm×9.4 cm×5.4 cm (L×W×H) and weight of 0.9 kg. The analyzer based on the custom-designed software of a smartphone (termed as UCNP-LFA analyzer) can get the quantitative analysis results in a real-time manner. We demonstrated the universality of this platform by highly sensitive and quantitative detections of several kinds of targets, including small molecule (ochratoxin A, OTA), heavy metal ion (Hg2+), bacteria (salmonella, SE), nucleic acid (hepatitis B virus, HBV) and protein (growth stimulation expressed gene 2, ST-2). Our developed UCNP-LFA platform holds great promise for applications in disease diagnostics, environmental pollution monitoring and food safety at the point of care.
关键词： UCNP-based biosensor,telemedicine,point-of-care diagnostics,paper microfluidics,multiplexed detection,miniaturized device
更新于2025-11-28 14:23:57
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Monolithic Wafer Scale Integration of Silicon Nanoribbon Sensors with CMOS for Lab-on-Chip Application
摘要： Silicon ribbons (SiRi) have been well-established as highly sensitive transducers for biosensing applications thanks to their high surface to volume ratio. However, selective and multiplexed detection of biomarkers remains a challenge. Further, very few attempts have been made to integrate SiRi with complementary-metal-oxide-semiconductor (CMOS) circuits to form a complete lab-on-chip (LOC). Integration of SiRi with CMOS will facilitate real time detection of the output signal and provide a compact small sized LOC. Here, we propose a novel pixel based SiRi device monolithically integrated with CMOS ?eld-effect-transistors (FET) for real-time selective multiplexed detection. The SiRi pixels are fabricated on a silicon-on-insulator wafer using a top-down method. Each pixel houses a control FET, ?uid-gate (FG) and SiRi sensor. The pixel is controlled by simultaneously applying frontgate (VG) and backgate voltage (VBG). The liquid potential can be monitored using the FG. We report the transfer characteristics (ID-VG) of N- and P-type SiRi pixels. Further, the ID-VG characteristics of the SiRis are studied at different VBG. The application of VBG to turn ON the SiRi modulates the subthreshold slope (SS) and threshold voltage (VTH) of the control FET. Particularly, N-type pixels cannot be turned OFF due to the control NFET operating in the strong inversion regime. This is due to large VBG (≥25 V) application to turn ON the SiRi sensor. Conversely, the P-type SiRi sensors do not require large VBG to switch ON. Thus, P-type pixels exhibit excellent ION/IOFF ≥ 106, SS of 70–80 mV/dec and VTH of 0.5 V. These promising results will empower the large-scale cost-ef?cient production of SiRi based LOC sensors.
关键词： silicon ribbon biosensor,SiRi backgate mode,silicon ribbon pixel,selective multiplexed detection,SiRi CMOS integration,SiRi frontgate mode,lab-on-chip
更新于2025-09-23 15:22:29
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Fluorometric immunoassay for the simultaneous determination of the tumor markers carcinoembryonic antigen and cytokeratin 19 fragment using two kinds of CdSe/ZnS quantum dot nanobeads and magnetic beads
摘要： A method is described for the simultaneous determination of the carcinoembryonic antigen (CEA) and cytokeratin 19 fragment (CYFRA21-1). Two kinds of CdSe/ZnS quantum dot nanobeads (QBs), with emission maxima at 530 nm (green) and 585 nm (yellow), were used as labels, and magnetic beads (MBs) for separation. The MBs were used as substrates to couple CEA and CYFRA21-1 antibody for isolating the proteins. Then, the differently colored QBs were linked to the antibodies against CEA and CYFRA21-1, respectively. Following the formation of the immunocomplex, the intensities of the green and yellow emissions were measured at the same excitation wavelength of 340 nm. The detection limits are 0.1 ng·mL?1 for CEA, and of 0.2 ng·mL?1 for CYFRA21-1. The recoveries from spiked serum are 92.1 - 118.1% for CEA, and from 90.8% to 115.2% for CYFRA21-1, with the relative standard deviations of 6.3 - 12.3% and 7.1 - 11.8%. The method was successfully applied to the simultaneous determination of the two proteins in human serum sample (n = 45). The results correlated well with those of the chemiluminescent enzyme immunoassay kit.
关键词： Lung cancer,Human serum,Fluorescence,Multiplexed detection,Antibody
更新于2025-09-23 15:19:57
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Digital Single Virus Immunoassay for Ultrasensitive Multiplex Avian Influenza Virus Detection Based on Fluorescent Magnetic Multifunctional Nanospheres
摘要： Fluorescence method has made great progress in the construction of sensitive sensors, but the background fluorescence of matrix and photobleaching limit its broad application in clinical diagnosis. Here, we propose a digital single virus immunoassay for multiplex virus detection by using fluorescent magnetic multifunctional nanospheres as both capture carriers and signal labels. The superparamagnetism and strong magnetic response ability of nanospheres can realize efficient capture and separation of targets without sample pretreatment. Due to its distinguishable fluorescence imaging and photostability, the nanospheres enable single-particle counting for ultrasensitive multiplexed detection. Furthermore, the integration of digital analysis provided a reliable quantitative strategy for rare targets detection. Based on multifunctional nanospheres and digital analysis, a digital single virus immunoassay was proposed for simultaneous detection of H9N2, H1N1 and H7N9 avian influenza virus (AIV) without complex signal amplification, whose detection limits were 0.02 pg/mL. Owing to its good specificity and anti-interference ability, the method showed great potential in single biomolecules, multiplexed detection and early diagnosis of diseases.
关键词： Multifunctional nanospheres,Digital analysis,Avian influenza virus,Single virus immunoassay,Ultrasensitive multiplexed detection
更新于2025-09-19 17:15:36
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Precisely Encoded Barcodes Using Tetrapod CdSe/CdS Quantum Dots with a Large Stokes Shift for Multiplexed Detection
摘要： A serious obstacle to the construction of high-capacity optical barcodes in suspension array technology is energy transfer, which can prompt unpredictable barcode signals, limited barcode numbers, and the need for an unfeasible number of experimental iterations. This work reports an effective and simple way to eliminate energy transfer in multicolor quantum dots (QDs)-encoded microbeads by incorporating tetrapod CdSe/CdS QDs with a large Stokes shift (about 180 nm). Exploiting this unique feature enables the facile realization of a theoretical 7 × 7-1 barcoding matrix combining two colors and seven intensity levels. As such, microbeads containing tetrapod CdSe/CdS QDs are demonstrated to possess a powerful encoding capacity which allows for precise barcode design. The ability of the Shirasu porous glass membrane emulsification method to easily control microbead size facilitates the establishment of a 3D barcode library of 144 distinguishable barcodes, indicating the enormous potential to enable large-scale multiplexed detection. Moreover, when applied for the multiplexed detection of five common allergens, these barcodes exhibit superior detection performance (limit of detection: 0.01–0.02 IU mL?1) for both spiked and patient serum samples. Therefore, this new coding strategy helps to expand barcoding capacity while simultaneously reducing the technical and economic barriers to the optical encoding of microbeads for high-throughput multiplexed detection.
关键词： large Stokes shift,F?rster resonance energy transfer (FRET),photon re-absorption,quantum dots-encoded microbeads,multiplexed detection
更新于2025-09-11 14:15:04