Development of nucleocapsid-specific monoclonal antibodies for SARS-CoV-2 and their ELISA diagnostics on an automatic microfluidic device.

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has threatened public health globally, and the emergence of viral variants has exacerbated an already precarious situation. To prevent further spread of the virus and determine government action required for virus control, accurate and rapid immunoassays for SARS-CoV-2 diagnosis are urgently needed. In this study, we generated monoclonal antibodies (mAbs) against the SARS-CoV-2 nucleocapsid protein (NP), compared their reactivity using an enzyme-linked immunosorbent assay (ELISA), and selected four mAbs designated 1G6, 3E10, 3F10, and 5B6 which have higher reactivity to NP and viral lysates of SARS-CoV-2 than other mAbs. Using an epitope mapping assay, we identified that 1G6 detected the C-terminal domain of SARS-CoV-2 NP (residues 248-364), while 3E10 and 3F10 bound to the N-terminal domain (residues 47-174) and 3F10 detected the N-arm region (residues 1-46) of SARS-CoV-2 NP. Based on the epitope study and sandwich ELISA, we selected the 1G6 and 3E10 Abs as an optimal Ab pair and applied them for a microfluidics-based point-of-care (POC) ELISA assay to detect the NPs of SARS-CoV-2 and its variants. The integrated and automatic microfluidic system could operate the serial injection of the sample, the washing solution, the HRP-conjugate antibody, and the TMB substrate solution simply by controlling air purge via a single syringe. The proposed Ab pair-equipped microsystem effectively detected the NPs of SARS-CoV-2 variants as well as in clinical samples. Collectively, our proposed platform provides an advanced protein-based diagnostic tool for detecting SARS-CoV-2.

Biosynthesis and applications of iron oxide nanocomposites synthesized by recombinant Escherichia coli.

Recombinant Escherichia coli (E. coli) strain that produces phytochelatin (PC) and/or metallothionein (MT) can synthesize various metal nanoparticles (NPs) by reducing metal ions. Here we report in vivo biosynthesis of iron oxide nanocomposites (NCs) using recombinant E. coli. We designed a strategy of biosynthesizing iron oxide NCs by first internalizing chemically synthesized iron oxide NPs, followed by the reduction of added metal ions on the surface of internalized NPs by PC and/or MT in E. coli. For this, chemically synthesized Fe3O4 NPs were internalized by recombinant E. coli, and then, Au and Ag ions were added for the biosynthesis of AuFe3O4 and AgFe3O4 NCs, respectively. The NCs synthesized were analyzed by transmission electron microscopy, UV-vis spectrophotometry, and X-ray diffractometry to characterize their shape, optical property, and crystallinity. The Fe3O4 NPs in the biosynthesized NCs allowed easy purification of the biosynthesized NCs by applying a magnetic field. The AuFe3O4 NCs were used for enzyme-linked immunosorbent assay to detect prostate-specific antigen protein, while AgFe3O4 NCs were utilized for the antimicrobial application with low minimum inhibitory concentration. As recombinant E. coli can uptake and reduce various NPs and metal ions, biosynthesis of a wide range of NCs as new nanomaterials will be possible for diverse applications. KEY POINTS: • AuFe3O4 and AgFe3O4 nanocomposites were synthesized by recombinant E. coli. • Escherichia coli synthesized different iron oxide NCs depending on the metal ions to be added. • Biosynthesized AuFe3O4 NC was used for ELISA and AgFe3O4 NC for antimicrobial tests.

Latent Class Analysis for Repeatedly Measured Multiple Latent Class Variables.

Research on stage-sequential shifts across multiple latent classes can be challenging in part because it may not be possible to observe the particular stage-sequential pattern of a single latent class variable directly. In addition, one latent class variable may affect or be affected by other latent class variables and the associations among multiple latent class variables are not likely to be directly observed either. To address this difficulty, we propose a multivariate latent class analysis for longitudinal data, joint latent class profile analysis (JLCPA), which provides a principle for the systematic identification of not only associations among multiple discrete latent variables but sequential patterns of those associations. We also propose the recursive formula to the EM algorithm to overcome the computational burden in estimating the model parameters, and our simulation study shows that the proposed algorithm is much faster in computing estimates than the standard EM method. In this work, we apply a JLCPA using data from the National Longitudinal Survey of Youth 1997 in order to investigate the multiple drug-taking behavior of early-onset drinkers from their adolescence, via young adulthood, to adulthood.

Developing a Loop-Mediated Isothermal Amplification Assay for the Rapid Detection of Seven Respiratory Viruses including SARS-CoV-2.

Background and Objectives: The coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to be a pandemic even in 2022. As the initial symptoms of COVID-19 overlap with those of infections from other respiratory viruses, an accurate and rapid diagnosis of COVID-19 is essential for administering appropriate treatment to patients. Currently, the most widely used method for detecting respiratory viruses is based on real-time polymerase chain reaction (PCR) and includes reverse-transcription real-time quantitative PCR (RT-qPCR). However, RT-qPCR assays require sophisticated facilities and are time-consuming. This study aimed to develop a real-time quantitative loop-mediated isothermal amplification (RT-qLAMP) assay and compare its analytical performance with RT-qPCR. Materials and Methods: A total of 315 nasopharyngeal swabs from patients with symptoms of respiratory infections were included in this study. A primary screening of the specimens was performed using RT-qPCR. RNA/DNA from standard strains for respiratory viruses and heat-inactivated preparations of standard strains for SARS-CoV-2 were used to evaluate the accuracy and target specificity of the RT-qLAMP assay. Results: We successfully developed an RT-qLAMP assay for seven respiratory viruses: respiratory syncytial virus (RSV) A, RSV B, adenovirus, influenza (Flu) A (H1N1 and H3N2), Flu B, and SARS-CoV-2. RT-qLAMP was performed in a final reaction volume of 9.6 µL. No cross-reactivity was observed. Compared with the RT-PCR results, the sensitivity and specificity of the RT-qLAMP assay were 95.1% and 100%, respectively. The agreement between the two methods was 97.1%. The median amplification time to RT-qLAMP positivity was 22:34 min (range: 6:80-47:98 min). Conclusions: The RT-qLAMP assay requires a small number of reagents and samples and is performed with an isothermal reaction. This study established a fast, simple, and sensitive test that can be applied to point-of-care testing devices to facilitate the detection of respiratory viruses, including SARS-CoV-2.

A micrometer head integrated microfluidic device for facile droplet size control and automatic measurement of a droplet size.

A novel microfluidic droplet generator is proposed, which can control the droplet size through turning an integrated micrometer head with ease, and the size of the produced micro-droplet can be automatically and real-time monitored by an open-sourced software and off-the-shelf hardware.

Combination of a centrifugal microfluidic device with a solution-loading cartridge for fully automatic molecular diagnostics.

We present a centrifugal microfluidic device which is combined with a solution-loading cartridge for fully automatic molecular diagnostics of foodborne pathogens. The proposed device could perform all processes of molecular diagnostics including bead-based DNA extraction, isothermal DNA amplification and colorimetric amplicon detection. In particular, the 3D-printed solution-loading cartridge was incorporated into the device to enhance the sample handling capacity and eliminate laborious steps such as pipetting for sample loading and sealing the top of the device. The cartridge could store four kinds of essential solutions (a sample solution, a washing solution, an elution solution, and a loop-mediated isothermal amplification (LAMP) cocktail) for pathogen detection, and the designated solutions were automatically released into the microdevice in a consecutive order by rotation. Since one unit of a device contains 20 reaction chambers, 18 kinds of pathogens plus two controls can be simultaneously detected in one test. As a proof-of-concept, we targeted four kinds of foodborne pathogens (Escherichia coli O157:H7, Salmonella typhimurium, Vibrio parahaemolyticus and Listeria monocytogenes) and successfully verified them, demonstrating that the centrifugal microdevice could be combined with a 3D printed solution-loading cartridge to achieve fully automated lab-on-a-chip-based molecular diagnostics. The entire process was completed in 65 min, and the limit of detection of the assay was 100 bacterial cells. The employment of the solution-loading cartridge successfully replaced the laborious and error-prone manual loading processes, which realized true automation of molecular diagnostics. This device could have promise in the fields of lab-on-a-chip and point-of-care molecular diagnostics.

Clinical Outcomes of the Seal® Thoracic Stent Graft for Traumatic Aortic Injury in a Korean Multicenter Retrospective Study.

BACKGROUND: Thoracic endovascular aneurysm repair (TEVAR) has been used as a primary treatment for blunt traumatic aortic injury (TAI). However, the outcomes of midterm surveillance of Seal® stent-graft durability for TAI have not been extensively studied. Thus, we aimed to report the midterm outcomes of TEVAR using the Seal® stent graft for blunt TAI. METHODS: Patients with blunt TAI treated with TEVAR using the Seal® thoracic stent graft between 2007 and 2013 in Korea were included. Midterm outcomes included technical/clinical success, in-hospital death, aorta/procedure/device-related adverse events, secondary procedures, and 30-day and all-cause mortality. RESULTS: A total of 99 patients (54% men; mean age, 48 years) were included. Grade III or higher injuries were present in 95% of patients, including 15 free ruptures of the thoracic aorta, and 64% of injuries were located in zone III. The median procedure and hospitalization duration were 90 min and 11 days, respectively. The technical success rate was 98%. The number of in-hospital mortalities (n = 8) and stroke (n = 2) were observed at 30 days. Late stroke and paraplegia (>30 days) were not observed during the mean 49 ± 26 months of follow-up (median, 48 months; range, 0-117 months). There were no aorta-related mortalities or conversions to open repair. Secondary procedures were performed in 8 patients, all of which were carotid-subclavian bypasses for delayed left subclavian occlusion. The all-cause mortality rate was 5% at 30 days and 8% at 1 year. The survival rate was 95% at 30 days, 92% at 1 year, 92% at 3 years, and 89% at 5 years. One type Ia endoleak occurred at 18 months after the procedure. CONCLUSIONS: TEVAR with the Seal® stent graft for TAI showed favorable midterm outcomes. The incidence of major adverse events after the procedure was low.

In Vivo Synthesis of Nanocomposites Using the Recombinant Escherichia coli.

Biogenic gold nanorod (AuNR)-Ag core-shell nanocomposites (NCs) are synthesized by using recombinant Escherichia coli to demonstrate in vivo synthesis of biogenic NCs for the first time. The chemically synthesized AuNRs are internalized into the E. coli, and Ag ions are reduced and grown on the surface of the AuNRs with the assistance of metal-binding proteins, producing biogenic core-shell AuNR-Ag NCs. The core-shell structure of the biogenic AuNR-Ag NC is confirmed by transmission electron microscopy and energy-dispersive X-ray analysis. The biogenic AuNR-Ag NCs exhibit good plasmonic effects. While the core-shell morphology of the AuNR and Ag NCs is due to the similar lattice of Au and Ag, the shape of the biogenic NCs composed of gold nanoparticles and Fe is aciniform, and that of Fe3 O4 NPs and Au/Ag is a network structure, demonstrating the controllability of biogenic nanosynthesis using diverse metal combinations with different NC morphologies.

Investigation on the Nucleation Stage of Palladium Nanoparticles Using a Microfluidic Droplet Generator Integrated with In Situ Sol-Gel Quencher.

The nanoparticle (NP) synthesis undergoes stepwise processes starting from the input metal ions: nucleation, coalescence, ripening, and growth. Considering the whole process is completed in a very short time, the conventional flask-scale method, which requires at least minutes, is not adequate to trace the mechanism of NP nucleation. In this study, a microfluidic droplet generator is developed, which is capable of in situ sol-gel polymerization for synthetic reaction quenching. As a model, palladium (Pd) NPs are synthesized within microdroplets, and the reaction time is controlled by tuning the length of the microchannel. In the microfluidic design, the outmost microchannel is incorporated, in which tetraethyl orthosilicate (TEOS) dissolved in ethanol is injected. The generated droplets are merged to the outmost flow under the variety of time interval (50 to 5,000 ms), so that the tens of milliseconds observation on NP nucleation is conducted via flash-like sol-gel quenching. Based on the result analysis, the seeds of Pd NPs have undergone slight size fluctuation and then a thermodynamically stable aggregation/coalescence step within 5 s before moving into the growth stage. This microfluidic platform permits the study of the fundamental and initial stage of the NP synthesis, which cannot be approached by the conventional methodology.

Growth of Silver Nanowires from Controlled Silver Chloride Seeds and Their Application for Fluorescence Enhancement Based on Localized Surface Plasmon Resonance.

A "Polyol" method has granted low-cost and facile process-controllability for silver-nanowire (Ag-NW) synthesis. Although homogenous and heterogeneous nucleation and growth during Ag-NW synthesis are possible using polyol methods, heterogeneous nucleation and growth of Ag NW guarantees highly selective growth of nanostructures using silver chloride (AgCl) seeds, which provides a stable source of chloride ions (Cl-) and thermodynamic reversibility. In this paper, a microdroplet has been adopted to synthesize uniform AgCl seeds with different diameter that are used for seed-mediated Ag-NW synthesis. The concentration of two precursors (AgNO3 and NaCl) in the droplets is modulated to produce different sizes of AgCl seeds, which determines the diameter and length of Ag NWs. The process of the seed-mediated growth of Ag NWs has been monitored by observing the peak shift in the time-resolved UV-vis extinction spectrum. Furthermore, the distinct plasmonic property of Ag NWs for transverse and longitudinal localized-surface-plasmon-resonance (LSPR)-mediated fluorescence enhancement is utilized. The high aspect ratio and sharp tips work as simple antennas that induce the enhanced fluorescence emission intensity of a fluorophore, which can be applied in the fields of biological tissue imaging and therapy.

Clinical outcomes for endovascular repair of abdominal aortic aneurysm with the Seal stent graft.

OBJECTIVE: Since 2007, the availability of the Seal (S & G Biotech Inc, Seong-nam, Gyeonggi-do, Korea) stent graft for endovascular aneurysm repair (EVAR) has improved short-term outcomes in Korea. However, midterm outcome data are lacking. This retrospective study evaluated the midterm outcomes of 126 patients who underwent EVAR using the Seal stent graft between 2007 and 2010. METHODS: Data regarding use of the Seal stent graft for EVAR were collected from 16 Korean centers, and were analyzed retrospectively using Kaplan-Meier and Cox univariate and multivariate analyses. RESULTS: The mean patient age was 71 ± 8 years (median, 70; range, 49-87 years). Patients who were treated using a bifurcated graft (113; 90%) were generally symptomatic (56; 44%, which included 13 ruptured abdominal aortic aneurysms [10%]) and male (105; 83%). The primary technical success rate was 99%. Four patients (3%) died within 30 days, 5 patients (4%) died after 30 days, and 12 patients (9%) were lost to follow-up. The survival rates were 97% ± 2% (1 month), 97% ± 2% (3 months), 96% ± 2% (6 months), 96% ± 2% (1 year), 94% ± 3% (3 years), and 81% ± 10% (5 years). During a mean follow-up of 55 ± 22 months (median, 40; range, 0.03-91.2 months), 18 reinterventions were performed for 16 patients (13%). The freedom from reintervention rates were 96% ± 2% (1 month), 96% ± 2% (3 months), 94% ± 2% (6 months), 89% ± 3% (1 year), 84% ± 4% (3 years), and 57% ± 17% (5 years). The mean aneurysm diameter significantly decreased from 69.6 to 46.6 mm during the follow-up (P < .0001). A proximal neck of less than 15 mm, different simultaneous endoleaks, and insufficient bilateral coverage of the iliac aneurysm were associated with significantly higher rates of increased or unchanged aneurysm diameters (all P < .0001). Significantly higher rates of clinical failure were observed in patients who were less than 70 years old (P = .04), had a neck length of less than 15 mm (P = .02), and had a neck diameter of greater than 28 mm (P = .02). CONCLUSIONS: Most Seal stent grafts were implanted successfully (even in cases with a physical status of grade IV or higher or a ruptured abdominal aortic aneurysm), had an appropriate reintervention rate, and were stable during the midterm follow-up. However, there was a high rate of type I endoleak, which may be related to the early device model that we used. Therefore, long-term radiologic follow-up is recommended for the early detection of stent graft migration or endoleaks.

Combination of a Sample Pretreatment Microfluidic Device with a Photoluminescent Graphene Oxide Quantum Dot Sensor for Trace Lead Detection.

A novel trace lead ion (Pb(2+)) detection platform by combining a microfluidic sample pretreatment device with a DNA aptamer linked photoluminescent graphene oxide quantum dot (GOQD) sensor was proposed. The multilayered microdevice included a microchamber which was packed with cation exchange resins for preconcentrating metal ions. The sample loading and recovery were automatically actuated by a peristaltic polydimethylsiloxane micropump with a flow rate of 84 µL/min. Effects of the micropump actuation time, metal ion concentration, pH, and the volumes of the sample and eluent on the metal ion capture and preconcentration efficiency were investigated on a chip. The Pb(2+) samples whose concentrations ranged from 0.48 nM to 1.2 µM were successfully recovered with a preconcentration factor value between 4 and 5. Then, the preconcentrated metal ions were quantitatively analyzed with a DNA aptamer modified GOQD. The DNA aptamer on the GOQD specifically captured the target Pb(2+) which can induce electron transfer from GOQD to Pb(2+) upon UV irradiation, thereby resulting in the fluorescence quenching of the GOQD. The disturbing effect of foreign anions on the Pb(2+) detection and the spiked Pb(2+) real samples were also analyzed. The proposed GOQD metal ion sensor exhibited highly sensitive Pb(2+) detection with a detection limit of 0.64 nM and a dynamic range from 1 to 1000 nM. The on-chip preconcentration of the trace metal ions from a large-volume sample followed by the metal ion detection by the fluorescent GOQD sensor can provide an advanced platform for on-site water pollution screening.

Rapid, High-Throughput, and Direct Molecular Beacon Delivery to Human Cancer Cells Using a Nanowire-Incorporated and Pneumatic Pressure-Driven Microdevice.

Tracking and monitoring the intracellular behavior of mRNA is of paramount importance for understanding real-time gene expression in cell biology. To detect specific mRNA sequences, molecular beacons (MBs) have been widely employed as sensing probes. Although numerous strategies for MB delivery into the target cells have been reported, many issues such as the cytotoxicity of the carriers, dependence on the random probability of MB transfer, and critical cellular damage still need to be overcome. Herein, we have developed a nanowire-incorporated and pneumatic pressure-driven microdevice for rapid, high-throughput, and direct MB delivery to human breast cancer MCF-7 cells to monitor survivin mRNA expression. The proposed microdevice is composed of three layers: a pump-associated glass manifold layer, a monolithic polydimethylsiloxane (PDMS) membrane, and a ZnO nanowire-patterned microchannel layer. The MB is immobilized on the ZnO nanowires by disulfide bonding, and the glass manifold and PDMS membrane serve as a microvalve, so that the cellular attachment and detachment on the MB-coated nanowire array can be manipulated. The combination of the nanowire-mediated MB delivery and the microvalve function enable the transfer of MB into the cells in a controllable way with high cell viability and to detect survivin mRNA expression quantitatively after docetaxel treatment.

Is the Chain of Oxidation and Reduction Process Reversible in Luminescent Graphene Quantum Dots?

Graphene-based quantum dots (QDs) have received a tremendous amount of attention as a new type of light-emitting materials. However, their luminescence origins remain controversial due to extrinsic states of the impurities and disorder structures. Especially, the function of oxygen-contents should be understood and controlled as a crucial element for tuning the optical properties of graphene-based QDs. Herein, a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents are first synthesized via a direct oxidation route of graphite nanoparticle and thoroughly compared with a series of reduced GOQDs (rGOQDs) prepared by the conventional chemical reduction. Irreversible emission and different carrier dynamics are observed between the GOQDs and rGOQDs, although both routes show a similar tendency with regard to the variation of oxygen-functional components. Their luminescence mechanisms are closely associated with different atomic structures. The mechanism for the rGOQDs can be associated with a formation of small sp(2) nanodomains as luminescent centers, whereas those of GOQDs may be composed of oxygen-islands with difference sizes depending on oxidation conditions surrounded by a large area of sp(2) bonding. Important insights for understanding the optical properties of graphene-based QDs and how they are affected by oxygen-functional groups are shown.

Microchip-based forensic short tandem repeat genotyping.

Micro total analysis system (µTAS) or lab-on-a-chip (LOC) technology has advanced over decades, and the high performance for chemical and biological analysis has been well demonstrated with advantages of low sample consumption, rapid analysis time, high-throughput screening, and portability. In particular, µTAS or LOC based genetic applications have been extensively explored, and the short tandem repeat (STR) typing on a chip has garnered attention in the forensic community due to its special use for human identification in the field of mass disaster and missing person investigation, paternity testing, and perpetrator identification. The STR typing process consists of sample collection, DNA extraction, DNA quantitation, STR loci amplification, capillary electrophoretic separation, and STR profiling. Recent progress of microtechnology shows its ability to substitute the conventional analytical tools, and furthermore demonstrates total integration of the whole STR processes on a single wafer for on-site STR typing. In this review article, we highlighted some representative results for fluorescence labeling techniques, microchip-based DNA purification, on-chip polymerase chain reaction (PCR), a capillary electrophoretic microdevice, and a fully integrated microdevice for STR typing.

Quantitation of Oxidative Stress Gene Expression in Human Cell Lines Treated with Water-Dispersible MnO Nanoparticles.

The objective of this study was to assess cytotoxicity of engineered MnO nanoparticles by quantifying the reactive oxygen species (ROS) related genes (glutathione S-transferase (GST) and catalase) using real time-polymerase chain reaction (RT-PCR) and molecular beacon (MB) technologies. Monodisperse MnO nanoparticles of 14 nm in size were synthesized by the encapsulation of polyethyleneglycol (PEG)-phospholipid shell around the MnO core to endow high water-dispersibility and biocompatibility. In vitro cytotoxicity was evaluated at different concentrations (10, 50 and 100 µg/ml) and incubation times (12, 24 and 48 h) with human cancer cell lines (glioblastoma, lung adenocarcinoma and neuroblastoma cells). Both genetic and cellular cytotoxic screening methods produced consistent results, showing that GST and catalase ROS gene expression was maximized in 24 h incubation at 100 µg/ml concentration of MnO nanoparticles for each cell line. However, the cytotoxicity effect of the PEG-phospholipid coated MnO nanoparticle was not significant compared with control experiments, demonstrating its high potential in the applications of nanomedicines for a diagnostic and therapeutic tool.

Dual role of blue luminescent MoS2 quantum dots in fluorescence resonance energy transfer phenomenon.

Homogeneous blue luminescent MoS2 quantum dots are fabricated by using a lithium intercalation method from MoS2 nanoparticles, and the unique blue photoluminescence property is utilized in the Alexa Fluor 430-dsDNA-MoS2 FRET system, demonstrating the dual function of MoS2 quantum dots as a donor and an acceptor.

A single-incision technique for placement of implantable venous access ports via the axillary vein.

PURPOSE: To evaluate the technical feasibility and safety of a single-incision technique for placement of implantable venous access ports via the axillary vein. MATERIALS AND METHODS: Ports were placed in 216 patients between May and October 2012 using a single-incision technique via the axillary vein. Patients included 112 men and 104 women with a mean age of 58.2 years. After making a single vertical incision without subcutaneous tunneling, ports were placed via the left axillary vein in 172 patients and via the right axillary vein in 44 patients. Axillary vein punctures were directed medially at the incision site under ultrasound guidance. We retrospectively reviewed success rates, technical difficulties, procedure times, and immediate and delayed complications of the procedure. RESULTS: All single-incision port placements were technically successful. Technical difficulties occurring during the procedure included advancement of the wire or catheter into an unintended vein (n = 33), kinking at the cuff-catheter junction (n = 13), bleeding via the puncture tract (n = 5), bending of the peel-away sheath (n = 3), and puncture of the axillary artery (n = 3). All technical problems were overcome with additional manipulation. The only immediate complication was puncture site hematoma in two patients. The mean follow-up period was 165.7 days, and there were no reports of port malfunction. Axillary vein thrombosis was observed in one patient. CONCLUSIONS: The single-incision technique for placing ports via the axillary vein was a feasible and safe procedure with high technical success and low risk of complications.

Development of a self-contained microfluidic chip and an internet-of-things-based point-of-care device for automated identification of respiratory viruses.

The COVID-19 pandemic greatly impacted the in vitro diagnostic market, leading to the development of new technologies such as point-of-care testing (POCT), multiplex testing, and digital health platforms. In this study, we present a self-contained microfluidic chip integrated with an internet-of-things (IoT)-based point-of-care (POC) device for rapid and sensitive diagnosis of respiratory viruses. Our platform enables sample-to-answer diagnostics within 70 min by automating RNA extraction, reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and fluorescence detection. The microfluidic chip is designed to store all the necessary reagents for the entire diagnostic assay, including a lysis buffer, a washing buffer, an elution buffer, and a lyophilized RT-LAMP cocktail. It can perform nucleic acid extraction, aliquoting, and gene amplification in multiple reaction chambers without cross-contamination. The IoT-based POC device consists of a Raspberry Pi 4 for device control and data processing, a CMOS sensor for measuring fluorescence signals, a resistive heater panel for temperature control, and solenoid valves for controlling the movement of on-chip reagent solutions. The proposed device is portable and features a touchscreen for user control and result display. We evaluated the performance of the platform using 11 clinical respiratory virus samples, including 5 SARS-CoV-2 samples, 2 influenza A samples, and 4 influenza B samples. All tested clinical samples were accurately identified with high specificity and fidelity, demonstrating the ability to simultaneously detect multiple respiratory viruses. The combination of the integrated microfluidic chip with the POC device offers a simple, cost-effective, and scalable solution for rapid molecular diagnosis of respiratory viruses in resource-limited settings.

Feasibility and Safety of a Technique Intended to Place the Catheter Tip in the Right Atrium without Abutment Against the Cardiac Wall during Implantation of the Totally Implantable Venous Access Port.

Purpose: To assess the safety and feasibility of intentionally positioning the catheter tip in the right atrium (RA) without an abutment during implantation of a totally implantable venous access port (TIVAP). Materials and Methods: We enrolled 330 patients who had undergone TIVAP implantation between January and December 2016 and postoperative chest CT. The TIVAP was placed using the single-incision technique to access the axillary vein directly from the incision line. To position the catheter tip in the RA without abutment, blood return was checked before cutting. Catheter length and complications were evaluated by retrospectively reviewing medical images and records. Results: All patients achieved successful catheter tip positioning without abutment or dysfunction. The median tip position was 15.3 mm distal to the cavoatrial junction (CAJ) on fluoroscopy and 6 mm distal to the CAJ on CT. Catheter tips migrated a median of 10.4 mm cephalically on CT compared to fluoroscopy. Thromboses were detected in the RA and superior vena cava in one patient each. Conclusion: Intentional catheter tip positioning in the RA without abutment is a safe and feasible technique with a low incidence of thrombosis and no observed dysfunction.