A microbead-incorporated centrifugal sample pretreatment microdevice

Function of the Speech Recognition of the Smartphone to Automatically Operate a Portable Sample Pretreatment Microfluidic System

We proposed a portable sample pretreatment microsystem, which can be automatically operated through speech recognition in a smartphone app. The proposed sample pretreatment microsystem consists of a microfluidic chip, an air router, pressure and vacuum lines with air pump motors, six 3-way solenoid valves, and a microcontroller with a Bluetooth module. The command of a human voice conducted the whole process of DNA extraction from pathogenic bacterial samples. Thus, manual interference during the DNA extraction is eliminated, preventing any potential infection from human touch. The palm-sized sample pretreatment microsystem can be run by a portable battery or a conventional smartphone charger. Genomic DNA ofSalmonella typhimuriumwas purified on a chip in less than 1 min with an extraction efficiency of 70 ± 5%.

A finger-driven disposable micro-platform based on isothermal amplification for the application of multiplexed and point-of-care diagnosis of tuberculosis

Tuberculosis (TB) remains the high-risk infectious pathogen that caused global pandemic and high mortality, particularly in the areas lack in health resources. Clinical TB screening and diagnosis are so far mainly conducted on limited types of commercial platforms, which are expensive and require skilled personnel. In this work, we introduced a low-cost and portable finger-driven microfluidic chip (named Fd-MC) based on recombinase polymerase amplification (RPA) for rapid on-site detection of TB. After injection of the pre-treated sample solution, the pre-packaged buffer was driven by the pressure generated by the finger-actuated operation to accomplish sequential processes of diagnosis in a fully isolated microchannel. An in-situ fluorescence strategy based on FAM-probe was implemented for on-chip results read-out though a hand-held UV lamp. Hence, the Fd-MC proved unique advantageous for avoiding the risk of infection or environmental contamination. In addition, the Fd-MC was designed for multiplexed detection, which is able to not only identify TB/non-TB infection, but also differentiate between human Mycobacterium tuberculosis and Mycobacterium bovis. The platform was verified in 37 clinical samples, statistically with 100% specificity and 95.2% sensitivity as compared to commercial real-time RPA. Overall, the proposed platform eliminates the need on external pumps and skilled personnel, holding promise to POC testing in the resource-limited area.

Reciprocating flow-assisted nucleic acid purification using a finger-actuated microfluidic device

Molecular diagnostics can provide a powerful diagnostic tool since it can detect pathogens with high sensitivity, but complicated sample preparation procedures limit its widespread use as an on-site detection tool that relies on the skilled person and external equipment. To resolve these limitations, we report a solid-phase nucleic acid purification using a finger-actuated microfluidic device, which can control a set amount of flow regardless of differences in end-users. To increase the recovery rate, a finger-actuated reciprocator was newly developed and integrated into the microfluidic device that can efficiently react with silica microbeads and reagents. After verifying the finger-actuated microfluidic reciprocator, the effect of the reciprocating flow on the recovery rate was assessed to purify the standard DNA of the hepatitis B virus (HBV). The recovery rate was increased up to ∼50% and 955 to 955 000 IU mL^-1 of HBV standard DNA was successfully purified and detected by a real-time polymerase chain reaction. Furthermore, the proposed microfluidic device was exploited to purify the HBV DNA from the patient's blood plasma samples.

A lab-on-a-chip for free-flow electrophoretic preconcentration of viruses and gel electrophoretic DNA extraction

A lab-on-a-chip for FFE preconcentration of viruses and gel electrophoretic DNA extraction: complete preparation of amplifiable DNA from dilute specimens.

Sample-to-Answer Hepatitis B Virus DNA Detection from Whole Blood on a Centrifugal Microfluidic Platform with Double Rotation Axes

A point-of-care apparatus for hepatitis virus detection requires simple and easy-to-use processing steps and should have the same diagnostic capability as that in the central laboratory. However, no automated and efficient methods for hepatitis B virus (HBV) sample-to-answer detection include serum separation, and complete prestorage of reagents has been developed. We developed an automated sample-to-answer disc for rapid HBV detection from whole blood based on a double rotation axes centrifugal microfluidic platform. The disc with complete prestorage of reagents features fully automated and integrated serum separation from whole blood, magnetic bead-based DNA extraction, aliquoting of the nucleic acid, and real-time polymerase chain reaction. A laser diode for sequential release of prestored liquid reagents was used. Processing merely requires manual loading of the sample into the disc. We demonstrate successful sample-to-answer detection of HBV in a 500 μL whole blood sample with sample concentrations down to 10² copies/mL. The total time of the whole detection from sample-to-result is about 48 min. The disc provides a user-friendly molecular diagnostic system for rapid analysis of HBV without demanding a complicated laboratory instrument and major manual operation time. Overall, the results indicated that the developed disc could be used for HBV molecular diagnosis.

Permanent magnet actuation for magnetic bead-based DNA extraction

BACKGROUND

Recently, automatic molecular diagnostic devices to extract DNA have been extensively developed using magnetic beads. While various methods can be applied to the control of the beads, the efficiency of the control when incorporated in automatic devices has not been studied. This paper proposes a compact magnet actuation method for the control of magnetic beads for DNA extraction, and compares the efficiency to the already available magnetic bead-based DNA extraction device. A permanent magnet was preferred for its compactness, while an electro-magnet provides easy operation. After investigating various methods to actuate the magnet with perspective to the size, circuit complexity, and power requirement, we determined the solenoid actuation method to be most efficient. To further reduce the dimension of the overall actuation device, direct actuation of the permanent magnet to control the hold/release of the beads was employed in this paper. The proposed method was compared with the conventional solenoid actuator with a metal plunger. An experimental fluidics device was set up with a fluidic channel and a syringe pump. The bead holding performance against the fluid speed was tested while a fixed amount of beads was loaded into the center of the channel. The group velocity of the beads was analyzed via image processing to determine whether the magnet was sufficient to hold the beads. The required power and space was analyzed and compared qualitatively and quantitatively.

RESULT

The proposed direct actuation method was capable of holding the beads at faster fluidic speed than the conventional solenoid actuator. The required power was comparable contemplating the high initial power of the solenoid actuator, and required much smaller space since no plunger was needed.

CONCLUSIONS

The direct actuation of the permanent magnet using a solenoid coil showed enhanced performance in holding the beads via permanent magnet, with less complexity of the actuation circuit and space. The proposed method therefore can efficiently improve the overall performance of the bead-based DNA extraction.

Effect of buffer composition on PNA–RNA hybridization studied in the microfluidic microarray chip

Herein, we report that peptide nucleic acid sequences (PNAs) have been used as the probe species for detection of RNA and that a microfluidic microarray (MMA) chip is used as the platform for detection of hybridizations between immobilized PNA probes and RNA targets. The RNA targets used are derived from influenza A sequences. This paper discusses the optimization of two probe technologies used for RNA detection and investigates how the composition of the probe buffer and the content of the hybridization solution can influence the overall results. Our data show that the PNA probe is a better choice than the DNA probe when there is low salt in the probe buffer composition. Furthermore, we show that the absence of salt (NaCl) in the hybridization buffer does not hinder the detection of RNA sequences. The results provide evidence that PNA probes are superior to DNA probes in term of sensitivity and adaptability, as PNA immobilization and PNA–RNA hybridization are less affected by salt content in the reaction buffers unlike DNA probes.

An integrated rotary microfluidic system with DNA extraction, loop-mediated isothermal amplification, and lateral flow strip based detection for point-of-care pathogen diagnostics

Point-of-care (POC) molecular diagnostics plays a pivotal role for the prevention and treatment of infectious diseases. In spite of recent advancement in microfluidic based POC devices, there are still rooms for development to realize rapid, automatic and cost-effective sample-to-result genetic analysis. In this study, we propose an integrated rotary microfluidic system that is capable of performing glass microbead based DNA extraction, loop mediated isothermal amplification (LAMP), and colorimetric lateral flow strip based detection in a sequential manner with an optimized microfluidic design and a rotational speed control. Rotation direction-dependent coriolis force and siphon valving structures enable us to perform the fluidic control and metering, and the use of the lateral flow strip as a detection method renders all the analytical processes for nucleic acid test simplified and integrated without the need of expensive instruments or human intervention. As a proof of concept for point-of-care DNA diagnostics, we identified the food-borne bacterial pathogen which was contaminated in water or milk. Not only monoplex Salmonella Typhimurium but also multiplex Salmonella Typhimurium and Vibrio parahaemolyticus were analysed on the integrated rotary genetic analysis microsystem with a limit of detection of 50 CFU in 80min. In addition, three multiple samples were simultaneously analysed on a single device. The sample-to-result capability of the proposed microdevice provides great usefulness in the fields of clinical diagnostics, food safety and environment monitoring.

Fully automated and colorimetric foodborne pathogen detection on an integrated centrifugal microfluidic device

This work describes fully automated and colorimetric foodborne pathogen detection on an integrated centrifugal microfluidic device, which is called a lab-on-a-disc. All the processes for molecular diagnostics including DNA extraction and purification, DNA amplification and amplicon detection were integrated on a single disc. Silica microbeads incorporated in the disc enabled extraction and purification of bacterial genomic DNA from bacteria-contaminated milk samples. We targeted four kinds of foodborne pathogens (Escherichia coli O157:H7, Salmonella typhimurium, Vibrio parahaemolyticus and Listeria monocytogenes) and performed loop-mediated isothermal amplification (LAMP) to amplify the specific genes of the targets. Colorimetric detection mediated by a metal indicator confirmed the results of the LAMP reactions with the colour change of the LAMP mixtures from purple to sky blue. The whole process was conducted in an automated manner using the lab-on-a-disc and a miniaturized rotary instrument equipped with three heating blocks. We demonstrated that a milk sample contaminated with foodborne pathogens can be automatically analysed on the centrifugal disc even at the 10 bacterial cell level in 65 min. The simplicity and portability of the proposed microdevice would provide an advanced platform for point-of-care diagnostics of foodborne pathogens, where prompt confirmation of food quality is needed.

A Review of Biomedical Centrifugal Microfluidic Platforms

Centrifugal microfluidic or lab-on-a-disc platforms have many advantages over other microfluidic systems. These advantages include a minimal amount of instrumentation, the efficient removal of any disturbing bubbles or residual volumes, and inherently available density-based sample transportation and separation. Centrifugal microfluidic devices applied to biomedical analysis and point-of-care diagnostics have been extensively promoted recently. This paper presents an up-to-date overview of these devices. The development of biomedical centrifugal microfluidic platforms essentially covers two categories: (i) unit operations that perform specific functionalities, and (ii) systems that aim to address certain biomedical applications. With the aim to provide a comprehensive representation of current development in this field, this review summarizes progress in both categories. The advanced unit operations implemented for biological processing include mixing, valving, switching, metering and sequential loading. Depending on the type of sample to be used in the system, biomedical applications are classified into four groups: nucleic acid analysis, blood analysis, immunoassays, and other biomedical applications. Our overview of advanced unit operations also includes the basic concepts and mechanisms involved in centrifugal microfluidics, while on the other hand an outline on reported applications clarifies how an assembly of unit operations enables efficient implementation of various types of complex assays. Lastly, challenges and potential for future development of biomedical centrifugal microfluidic devices are discussed.

LabDisk with complete reagent prestorage for sample-to-answer nucleic acid based detection of respiratory pathogens verified with influenza A H3N2 virus

Portable point-of-care devices for pathogen detection require easy, minimal and user-friendly handling steps and need to have the same diagnostic performance compared to centralized laboratories. In this work we present a fully automated sample-to-answer detection of influenza A H3N2 virus in a centrifugal LabDisk with complete prestorage of reagents. Thus, the initial supply of the sample remains the only manual handling step. The self-contained LabDisk automates by centrifugal microfluidics all necessary process chains for PCR-based pathogen detection: pathogen lysis, magnetic bead based nucleic acid extraction, aliquoting of the eluate into 8 reaction cavities, and real-time reverse transcription polymerase chain reaction (RT-PCR). Prestored reagents comprise air dried specific primers and fluorescence probes, lyophilized RT-PCR mastermix and stick-packaged liquid reagents for nucleic acid extraction. Employing two different release frequencies for the stick-packaged liquid reagents enables on-demand release of highly wetting extraction buffers, such as sequential release of lysis and binding buffer. Microfluidic process-flow was successful in 54 out of 55 tested LabDisks. We demonstrate successful detection of the respiratory pathogen influenza A H3N2 virus in a total of 18 LabDisks with sample concentrations down to 2.39 × 10(4) viral RNA copies per ml, which is in the range of clinical relevance. Furthermore, we detected RNA bacteriophage MS2 acting as internal control in 3 LabDisks with a sample concentration down to 75 plaque forming units (pfu) per ml. All experiments were applied in a 2 kg portable, laptop controlled point-of-care device. The turnaround time of the complete analysis from sample-to-answer was less than 3.5 hours.

An integrated slidable and valveless microdevice with solid phase extraction, polymerase chain reaction, and immunochromatographic strip parts for multiplex colorimetric pathogen detection

A total integrated genetic analysis microsystem was developed, which consisted of solid phase extraction (SPE), polymerase chain reaction (PCR), and immunochromatographic strip (ICS) parts for multiplex colorimetric detection of pathogenic Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7 (E. coli O157:H7) on a portable genetic analyzer. Utilizing a slidable chamber, which is a movable glass wafer, complex microvalves could be eliminated for fluidic control in the microchannel, which could simplify the chip design and chip operation. The integrated slidable microdevice was composed of 4 layers: a 4-point Pt/Ti resistance temperature detector (RTD) wafer, a micro-patterned channel wafer, a 2 μL volume slidable chamber, and an ICS. The entire process from the DNA extraction in the SPE chamber to the detection of the target gene expression by the ICS was serially performed by simply sliding the slidable chamber from one part to another functional part. The total process for multiplex pathogenic S. aureus and E. coli O157:H7 detection on the integrated slidable microdevice was accomplished within 55 min with a detection limit of 5 cells. Furthermore, spiked bacteria samples in milk were also successfully analysed on the portable genetic analysis microsystem with sample-in-answer-out capability. The proposed total integrated microsystem is adequate for point-of-care DNA testing in that no microvalves and complex tubing systems are required due to the use of the slidable chamber and the bulky and expensive fluorescence or electrochemical detectors are not necessary due to the ICS based colorimetric detection.

Integration of reverse transcriptase loop-mediated isothermal amplification with an immunochromatographic strip on a centrifugal microdevice for influenza A virus identification

A novel centrifugal microdevice which could perform reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) and immunochromatographic strip (ICS) based amplicon detection was demonstrated for simple and cost-effective influenza A virus identification. The proposed centrifugal microdevice consists of the sample and running buffer loading reservoirs, the RT-LAMP chamber, and the ICS for detecting gene expression. The entire process could be completed sequentially and automatically by simply controlling the rotation speed and by optimizing the microfluidic design. Monoplex and multiplex RT-LAMP reactions targeting H1 and/or M gene were executed at 66 °C for 40 min, and the resultant amplicons were successfully analysed on the ICS within 15 min. Influenza A H1N1 virus was subtyped by detecting H1 and M gene on the ICS even with 10 copies of viral RNAs. Highly specific and multiplex viral typing of the integrated RT-LAMP-ICS microdevice was also demonstrated. The combination of the rapid isothermal amplification with the simple colorimetric detection on a strip in a single centrifugal microdevice will provide an advanced genetic analysis platform in the field of on-site pathogen diagnostics.

Automated nucleic acid extraction from whole blood, B. subtilis, E. coli, and Rift Valley fever virus on a centrifugal microfluidic LabDisk

We present total nucleic acid extraction from whole blood, Gram-positiveBacillus subtilis, Gram-negativeEscherichia coli, andRift Valley feverRNA virus on a low-cost, centrifugal microfluidic cartridge processed in a portable processing device.

Centrifugal microfluidic platforms: advanced unit operations and applications

Review on miniaturization, integration, and automation of laboratory processes within centrifugal microfluidic platforms. For efficient implementation of applications, building blocks are categorized into unit operations and process chains.

Magnetic chemiluminescent immunoassay for human C-reactive protein on the centrifugal microfluidics platform

Schematic of the LabDisk-based hCRP MCIA. The antibody-coated dynabeads are sequentially transported through the immunoassay buffers by magnetic actuation. Finally the chemiluminescence signal is acquired from a detection cavity.

Integrated centrifugal reverse transcriptase loop-mediated isothermal amplification microdevice for influenza A virus detection

An integrated reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) microdevice which consists of microbead-assisted RNA purification and RT-LAMP with real-time monitoring by a miniaturized optical detector was demonstrated. The integrated RT-LAMP microdevice includes four reservoirs for a viral RNA sample (purified influenza A viral RNA or lysates), a washing solution (70% ethanol), an elution solution (RNase-free water), and an RT-LAMP cocktail, and two chambers (a waste chamber and an RT-LAMP reaction chamber). The separate reservoirs for a washing solution, an elution solution, and an RT-LAMP cocktail were designed with capillary valves for stable storage. Three influenza A virus strains (A/H1N1, A/H3N2, and A/H5N1) were used for RNA templates, and RT-LAMP primer sets were designed to detect hemagglutinin (HA) and conserved M gene. Sequential sample flow to the microbeads for RNA purification was achieved by centrifugal force with optimization of capillary valves and a siphon channel. Furthermore, the purified RNA solution was successfully isolated from the waste solution by changing the rotational direction, and combined with the RT-LAMP cocktail in the RT-LAMP reaction chamber for target gene amplification. Total process from the sample injection to the result was completed in 47 min. Influenza A H1N1 virus was confirmed on the integrated RT-LAMP microdevice even with 10 copies of viral RNAs, which revealed 10-fold higher sensitivity than that of a conventional RT-PCR. Subtyping and specificity test of influenza A H1N1 viral lysates were also performed and clinical samples were successfully genotyped to confirm influenza A virus on our proposed integrated microdevice.

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An integrated microdevice cosistng of RNA purification and RT-LAMP with real-time monitoring was demonstrated.

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Sequential sample transportation and purified RNA separation were automatically controlled by centrifugal force and optimized microchannels.

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Influenza viruses were isothermally amplified and the products were identified by using a miniaturized fluorescence detector.

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Limit of detection for influenza A H1N1 was 10 copies.

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Clinical samples were successfully analyzed on the microdevice.

Combination of multiplex reverse-transcription loop-mediated isothermal amplification with an immunochromatographic strip for subtyping influenza A virus

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Multiplex RT-LAMP for HA and M genes was developed for subtyping influenza A virus.

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Multiplex RT-LAMP amplicons were simply analyzed by the colorimetric ICS detection.

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Multiplex RT-LAMP (40 min) and ICS detection (15 min) could be complete in 55 min.

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Detection sensitivity for the multiplex RT-LAMP and ICS was 10 copies of viral RNA.

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Our methodology provides simple, rapid genetic analysis platform for viral detection.

Considering the fatal human victims and economic loss by the annual epidemic influenza virus, the development of a rapid and convenient genetic analysis methodology is demanding for timely on-site pathogen detection. In this study, we utilized reverse-transcription loop-mediated isothermal amplification (RT-LAMP) for multiplex target gene amplification, and the resultant amplicons were analyzed on the immunochromatographic strip (ICS) for subtyping influenza A virus. Through the optimized primer design, reaction temperature and time, and concentration of enzymes (Bst DNA polymerase and AMV reverse transcriptase) and dNTP, the HA (H1, H3, and H5 gene) and conserved M gene were amplified. The ICS contains two test lines in addition to a control line in order to detect the presence of the HA and M gene, thereby informing us of influenza virus A type as well as its subtype (H1N1, H3N2, and H5N1). The combination of the multiplex RT-LAMP with the ICS could be complete in 40 min and the pathotyping and subtyping of influenza A virus were performed even with 10 copies of viral RNA templates. Moreover, the subtyping of clinical samples, which were obtained from patients infected by influenza A virus was successfully confirmed using the multiplex RT-LAMP and ICS techniques, showing great feasibility of our methodology for real sample analysis with high speed, simplicity and sensitivity.

A packaged paper fluidic-based microdevice for detecting gene expression of influenza A virus

Pathotyping and subtyping of influenza A virus were performed with a packaged paper fluidic-based analytical microdevice (PFAM) after one-step reverse transcription-polymerase chain reaction (RT-PCR). The PFAM contains two test lines: one for detecting M gene to identify the influenza A virus and another for haemagglutinin subtyping to determine the viral strain among H1N1, H3N2, and H5N1. The M gene and the haemagglutinin gene (H1, H3, and H5 genes) were amplified by using the Digoxigenin and the Texas Red modified primers, respectively, in the multiplex RT-PCR. The amplicon products were loaded in the conjugate pad of the PFAM in which the streptavidin coated gold nanoparticles were linked with the biotin moieties that were incorporated in the middle of the DNA strands, and then captured by the anti-Digoxigenin and anti-Texas Red immobilized on the test lines. Influenza A H1N1, H3N2, and H5N1 could be identified with a limit of detection of 10(2) copies of RNA templates in 10 min. Pathotyping and subtyping of the clinical nasopharyngeal swab samples were also analyzed whose results were confirmed by real-time RT-PCR.