Electro-Optical Multiclassification Platform for Minimizing Occasional Inaccuracy in Point-of-Care Biomarker Detection.

On-site diagnostic tests that accurately identify disease biomarkers lay the foundation for self-healthcare applications. However, these tests routinely rely on single-mode signals and suffer from insufficient accuracy, especially for multiplexed point-of-care tests (POCTs) within a few minutes. Here, this work develops a dual-mode multiclassification diagnostic platform that integrates an electrochemiluminescence sensor and a field-effect transistor sensor in a microfluidic chip. The microfluidic channel guides the testing samples to flow across electro-optical sensor units, which produce dual-mode readouts by detecting infectious biomarkers of tuberculosis (TB), human rhinovirus (HRV), and group B streptococcus (GBS). Then, machine-learning classifiers generate three-dimensional (3D) hyperplanes to diagnose different diseases. Dual-mode readouts derived from distinct mechanisms enhance the anti-interference ability physically, and machine-learning-aided diagnosis in high-dimensional space reduces the occasional inaccuracy mathematically. Clinical validation studies with 501 unprocessed samples indicate that the platform has an accuracy approaching 99%, higher than the 77%-93% accuracy of rapid point-of-care testing technologies at 100% statistical power (>150 clinical tests). Moreover, the diagnosis time is 5 min without a trade-off of accuracy. This work solves the occasional inaccuracy issue of rapid on-site diagnosis, endowing POCT systems with the same accuracy as laboratory tests and holding unique prospects for complicated scenes of personalized healthcare.

An Alternating Current Electroosmotic Flow-Based Ultrasensitive Electrochemiluminescence Microfluidic System for Ultrafast Monitoring, Detection of Proteins/miRNAs in Unprocessed Samples.

Early diagnosis of acute diseases is restricted by the sensitivity and complex process of sample treatment. Here, an ultrasensitive, rapid, and portable electrochemiluminescence-microfluidic (ECL-M) system is described via sandwich-type immunoassay and surface plasmonic resonance (SPR) assay. Using a sandwich immunoreaction approach, the ECL-M system employs cardiac troponin-I antigen (cTnI) as a detection model with a Ru@SiO2 NPs labeled antibody as the signal probe. For miR-499-5p detection, gold nanoparticles generate SPR effects to enhance Ru(bpy)3 2+ ECL signals. The system based on alternating current (AC) electroosmotic flow achieves an LOD of 2 fg mL-1 for cTnI in 5 min and 10 aM for miRNAs in 10 min at room temperature. The point-of-care testing (POCT) device demonstrated 100% sensitivity and 98% specificity for cTnI detection in 123 clinical serum samples. For miR-499-5p, it exhibited 100% sensitivity and 97% specificity in 55 clinical serum samples. Continuous monitoring of these biomarkers in rats' saliva, urine, and interstitial fluid samples for 48 hours revealed observations rarely documented in biotic fluids. The ECL-M POCT device stands as a top-performing system for ECL analysis, offering immense potential for ultrasensitive, rapid, highly accurate, and facile detection and monitoring of acute diseases in POC settings.

Innovative Highly Specific Nucleic Acid Isothermal Detection Assay Based on the Polymerization-Coupled Endonuclease Activity of Prokaryotic DNA Polymerase I.

In this study, we developed an innovative highly specific nucleic acid isothermal detection assay based on prokaryotic DNA polymerase I with exquisitely designed fluorescent probes, achieving high sensitivity and 100% specificity within 30 min. The fluorescent nucleic acid probe was designed and constructed based on the specific flap cleavage endonuclease activity of prokaryotic DNA polymerase I (including the Bst, Bsu, Bsm, and Klenow DNA polymerases). The flap endonuclease activity depends on the length of the flap DNA and polymerization activity, which greatly reduces the false-positive rate caused by primer dimerization. This robust assay was also validated by the detection of rotavirus with great specificity and sensitivity. It could be a great alternative to qPCR in the field of point-of-care detection of pathogens.

Methylene-Blue-Encapsulated Metal-Organic-Framework-Based Electrochemical POCT Platform for Multiple Detection of Heavy Metal Ions in Milk.

Considering the high risk of heavy metal ions (HMIs) transferring through the food chain and accumulating in milk, a flexible and facile point-of-care testing (POCT) platform is urgently needed for the accurate, sensitive, and highly selective on-site quantification of multiple HMIs in milk. In this work, a cost-effective disk with six screen-printed electrodes (SPEs) was designed for hand-held electrochemical detection. Metal organic frameworks (MOFs) were adopted to amplify and enhance the electrochemical signals of methylene blue (MB). Using differential pulse voltammetry (DPV) methods, low limits of detection for four HMIs (Cd2+, 0.039 ppb; Hg2+, 0.039 ppb; Pb2+, 0.073 ppb; and As3+, 0.022 ppb) were achieved within four minutes. Moreover, the quantitative POCT system was applied to milk samples. The advantages of low cost, ease of on-site implementation, fast response, and accuracy allow for the POCT platform to be used in practical monitoring applications for the quantitation of multiple HMIs in milk samples.

Electrolytic Corrosion Behavior of 20 Cu-20 Ni-54 NiFe2O4-6 NiO Cermet with Interpenetrating Structure at 880 °C and 960 °C.

Here, 20 Cu-20 Ni-54 NiFe2O4-6 NiO (wt%) cermets were prepared via the powder metallurgy process, and the electrolytic corrosion behavior of the cermets at 880 °C and 960 °C was studied through the microstructure analysis by SEM and EDS. Results show that the ceramic phase is seriously affected by chemical corrosion at 880 °C electrolysis, and it is difficult to form a dense ceramic surface layer. A dense ceramic surface layer is formed on the bottom of the anode electrolyzed at 960 °C, and the dense layer thickens with the extension of the electrolysis time. The formation of the dense surface layer is mainly caused by the oxidation of Ni. The oxidation rate of the metallic phase and the corrosion rate of the ceramic phase have an important effect on the formation of the dense layer. In the corrosion process of NiFe2O4 phase, preferential corrosion of Fe element occurs first, and then NiO phase is precipitated from NiFe2O4 phase. After the NiO is dissolved and corroded, the NiFe2O4 grains collapse and the ceramic phase peels off from the anode.

Aptamer-Initiated Catalytic Hairpin Assembly Fluorescence Assay for Universal, Sensitive Exosome Detection.

Cancer-cell-derived exosomes are regarded as noninvasive biomarkers for early cancer diagnosis because of their critical roles in intercellular communication and molecular exchange. A robust aptamer-initiated catalytic hairpin assembly (AICHA) fluorescence assay is proposed for universal, sensitive detection of cancer-derived exosomes. The AICHA was verified with the specific detection of MCF-7 cell-derived exosomes with a wide calibration range of 8.4 particles/µL to 8.4 × 105 particles/µL and a low detection limit (LOD) of 0.5 particles/µL. The universality of the AICHA method was verified for PANC-1 cell-derived exosomes, the LOD of which was determined to be 0.1 particles/µL. The performances in serum samples were detected with a recovery rate range of 95.45-106.2%, which demonstrates its significant potential for protein biomarker analysis and cancer diagnosis.

Surface Plasmon Coupling Electrochemiluminescence Immunosensor Based on Polymer Dots and AuNPs for Ultrasensitive Detection of Pancreatic Cancer Exosomes.

Polymer dots (Pdots) have become attractive electrochemiluminescence (ECL) luminophores due to their facile synthesis, easy modification, and stable electrochemical and optical properties. However, their ECL efficiency is not high enough for practical applications. In this work, we proposed an ECL immunosensor based on localized surface plasmon resonance (LSPR) between AuNPs and Pdots for the determination of pancreatic cancer exosomes. Based on the finite-difference time-domain simulations and the band energy of Pdots and AuNPs, we proposed the possible LSPR mechanism. The hot electrons of plasmonic AuNPs were photoexcited to surface plasmon states by ECL emission of Pdots, and then the excited hot electrons were transferred to the conduction band of Pdots, which significantly improved the ECL efficiency of Pdots. The ECL immunosensor displayed a wide calibration range of 1.0 × 103 to 1.0 × 106 particles/mL with a detection limit of 400 particles/mL. Cancer-related protein profiling revealed high selectivity toward different expressions of exosomal surface proteins from PANC-01, HeLa, MCF-7, and HPDE6-C7 cell lines. The proposed ECL system exhibits a promising prospect for protein biomarker profiling and early cancer-related diagnosis.

Recent Progress in Detection and Profiling of Cancer Cell-Derived Exosomes.

Exosomes, known as nanometer-sized vesicles (30-200 nm), are secreted by many types of cells. Cancer-derived exosomes have great potential to be biomarkers for early clinical diagnosis and evaluation of cancer therapeutic efficacy. Conventional detection methods are limited to low sensitivity and reproducibility. There are hundreds of papers published with different detection methods in recent years to address these challenges. Therefore, in this review, pioneering researches about various detection strategies are comprehensively summarized and the analytical performance of these tests is evaluated. Furthermore, the exosome molecular composition (protein and nucleic acid) profiling, a single exosome profiling, and their application in clinical cancer diagnosis are reviewed. Finally, the principles and applications of machine learning method in exosomes researches are presented.

Efficient Microfluidic-Based Air Sampling/Monitoring Platform for Detection of Aerosol SARS-CoV-2 On-site.

Airborne pathogens have been considered as highly infectious and transmittable between humans. With the pandemic outbreak of the coronavirus disease 2019 (COVID-19), an on-site diagnostic system-integrated airborne pathogen-monitoring machine is recommended by experts for preventing and controlling the early stage ß-coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread. In this work, a small-volume rotating microfluidic fluorescence chip-integrated aerosol SARS-CoV-2 sampling system was constructed to satisfy the demand for rapid on-site sample collection and detection of SARS-CoV-2. The rotating microfluidic fluorescence system with small volume has very high sensitivity in the detection of SARS-CoV-2 (detection limit of 10 copies/µL with the shortest Ct value of 15 min), which is comparable to reverse transcription polymerase chain reaction (RT-PCR). The precision variation coefficients within/between batches are very low [coefficient of variation (CV) % ≤ 5.0%]. Our work has passed the comprehensive inspection of the microfluidic chip performance by the Shanghai Medical Device Testing Institute [National Medical Inspection (Design) no. 4408] and successfully tested 115 clinical samples. The integrated system exhibits 100% specificity, high sensitivity (10 copies/µL), and good precision (CV % ≤ 5.0%) in the rapid detection of SARS-CoV-2, thus realizing rapid monitoring and diagnostics of SARS-CoV-2 nucleic acid on-site.

Rapid Differential Diagnosis of Seven Human Respiratory Coronaviruses Based on Centrifugal Microfluidic Nucleic Acid Assay.

With the global outbreak of the coronavirus disease 2019 (COVID-19), the highly infective, highly pathogenic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has attracted great attention. Currently, a method to simultaneously diagnose the seven known types human coronaviruses remains lacking and is urgently needed. In this work, we successfully developed a portable microfluidic system for the rapid, accurate, and simultaneous detection of SARS-CoV, middle east respiratory syndrome coronavirus (MERS-CoV), SARS-CoV-2, and four other human coronaviruses (HCoVs) including HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1. The disk-like microfluidic platform integrated with loop-mediated isothermal amplification provides highly accurate, sensitive, and specific results with a wide linear range within 40 min. The diagnostic tool achieved 100% consistency with the "gold standard" polymerase chain reaction in detecting 54 real clinical samples. The integrated system, with its simplicity, is urgently needed for the diagnosis of SARS-CoV-2 during the COVID-19 pandemic.

Construction of an ultrasensitive electrochemiluminescent aptasensor for ractopamine detection.

In this study, an ultrasensitive electrochemiluminescence (ECL) aptasensor based on Ru(bpy)32+-doped silica nanoparticles (Ru@SiO2 NPs) coupled with gold nanoparticles (Au NPs) was developed for the determination of ractopamine (Rac). TPrA is used as the coreactant, the Ru@SiO2 NPs serve as the ECL luminophores, and the Au NPs work as a catalyzer in the redox reaction as well as the carrier that immobilizes the aptamer. Meanwhile, the complete incorporation of the Ru@SiO2 NPs and Au NPs increases the localized surface plasmon resonance (LSPR) probability, thus promoting ECL emission. The ractopamine (Rac) target molecules are specifically captured on the electrode surface by aptamer recognition. The ECL signal is quenched by energy transfer from the luminophore to benzoquinone compounds, which are oxidative products of Rac from the electrochemical scanning process. The proposed ECL aptasensor exhibits ultrahigh sensitivity and excellent selectivity for Rac detection. The linear response ranged over Rac concentrations from 1.5 × 10-12 M to 1.5 × 10-8 M with a detection limit of 4.1 × 10-14 M (S/N = 3). The detection recovery of Rac in real meat samples confirmed the satisfactory performance of the method. This study describes a versatile ECL aptasensor based on the combined functions of luminous nanospheres and Au NPs, indicating its potential application for the ultrasensitive analysis of targets in diverse systems.

A near-infrared fluorescent probe for monitoring leucine aminopeptidase in living cells.

Leucine aminopeptidase (LAP), one of the important cancer-related biomarkers, is significantly over-expressed in many malignant tumor cells. Developing an effective fluorescent probe for high-specificity and in situ trapping of endogenous LAP in living samples is still challenging. In this project, we report a water-soluble near-infrared (NIR) fluorescent probe (CHMC-M-Leu) for specific monitoring of LAP in vitro and in vivo. The novel fluorescent probe (CHMC-M-Leu) contains a NIR-emitting fluorophore (CHMC-M) as the reporter and l-leucine as the enzyme-active trigger moiety which are linked together by a p-aminobenzyl alcohol (PABA) section. Upon exposure to LAP, the fluorescence at 625 nm gets impressively enhanced, which belongs to the near-infrared region and is beneficial for imaging in vivo. Furthermore, the novel fluorescent probe exhibits fast response and highly chemoselective detection of LAP in various bio-related species. In addition, CHMC-M-Leu shows favourable cellular uptake and was successfully used to monitor endogenous LAP in living cells.

Surface-enhanced molecularly imprinted electrochemiluminescence sensor based on Ru@SiO2 for ultrasensitive detection of fumonisin B1.

A novel molecularly imprinted electrochemiluminescence (MIP-ECL) sensor based on Ru(bpy)32+-doped silica nanoparticles (Ru@SiO2 NPs) is developed for highly sensitive detection of fumonisin B1 (FB1). Gold-nanoparticles (AuNPs), Ru@SiO2 NPs with chitosan (CS) composites and a molecularly imprinted polymer (MIP) are assembled on a glassy carbon electrode (GCE) to fabricate an ECL platform step by step. AuNPs could greatly promote the ECL intensity and improve the analytical sensitivity according to the localized surface plasmon resonance (LSPR) and the electrochemical effect. In this surface-enhanced electrochemiluminescence (SEECL) system, AuNPs work as the LSPR source to improve the ECL intensity and Ru@SiO2 NPs are used as ECL luminophores. In the phosphate buffer solution (PBS), the evident anodic ECL of Ru@SiO2 on the above working electrode is observed in the presence of the template molecule fumonisin B1 (FB1), which could act as the coreactant of Ru@SiO2 NPs due to the amino group of FB1. When the template molecules were eluted from the MIP, little coreactant was left, resulting in an apparent decrease of ECL signal. After the MIP-ECL sensor was incubated in FB1 solution, the template molecules rebound to the MIP surface, leading to the enhancement of ECL signal again. On the basis of these results, a facile MIP-ECL sensor has been successfully fabricated, which exhibited a linear range from 0.001 to 100ngmL-1 with a detection limit of 0.35pgmL-1 for FB1. Moreover, the proposed MIP-ECL sensor displayed an excellent application in real samples.