This study reports a new diagnostic assay for the rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) by combing nucleic acid extraction and isothermal amplification of target nucleic acids in a magnetic bead-based microfluidic system. By using specific probe-conjugated magnetic beads, the target deoxyribonucleic acid (DNA) of the MRSA can be specifically recognized and hybridized onto the surface of the magnetic beads which are then mixed with clinical sample lysates. This is followed by purifying and concentrating the target DNA from the clinical sample lysates by applying a magnetic field. Nucleic acid amplification of the target genes can then be performed by the use of a loop-mediated isothermal amplification (LAMP) process via the incorporation of a built-in micro temperature control module, followed by analyzing the optical density (OD) of the LAMP amplicons using a spectrophotometer. Significantly, experimental results show that the limit of detection (LOD) for MRSA in the clinical samples is approximately 10 fg μL(-1) by performing this diagnostic assay in the magnetic bead-based microfluidic system. In addition, the entire diagnostic protocol, from bio-sample pre-treatment to optical detection, can be automatically completed within 60 min. Consequently, this miniature diagnostic assay may become a powerful tool for the rapid purification and detection of MRSA and a potential point-of-care platform for detection of other types of infections.

This study presents a new magnetic bead-based microfluidic platform, which integrates three major modules for rapid leukocytes purification, genomic DNA (gDNA) extraction and fast analysis of genetic gene. By utilizing microfluidic technologies and magnetic beads conjugated with CD 15/45 antibodies, leukocytes in a human whole blood sample can be first purified and concentrated, followed by extraction of gDNA utilizing surface-charge switchable, DNA-specific, magnetic beads in the lysis solution. Then, specific genes associated with genetic diseases can be amplified by an on-chip polymerase chain reaction (PCR) process automatically. The whole pretreatment process including the leukocytes purification and gDNA extraction can be performed in an automatic fashion with the incorporation of the built bio-separators consisting of microcoils array within less than 20 min. The detection of single nucleotide polymorphism (SNP) genotyping of methylenetetra-hydrofolate reductase (MTHFR) C677T region associated with an increased risk of genetic diseases was further performed to demonstrate the capability of the proposed system. The extracted gDNA can be transported into a micro PCR chamber for on-chip fast nucleic acid amplification of detection genes with minimum human intervention. Hence, the developed system may provide a powerful automated platform for pretreatment of human leukocytes, gDNA extraction and fast analysis of genetic gene.

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This current study presents a new miniature, integrated system capable of rapid detection of genetic deletion from saliva samples. Several critical modules including a genomic DNA (gDNA) extraction module, a polymerase chain reaction (PCR) module, and an external optical detection module are integrated into the system. Silica-modified magnetic beads are first incubated with saliva in an extraction chamber with a cell lysis solution. This is followed by the collection of released gDNA onto the surface of the microbeads, which is then further purified and concentrated utilizing a magnetic field generated by an on-chip array of microcoils. Then, genetic deletion of human genes can be specifically amplified by the on-chip PCR module and is immediately detected using the optical detection module. Experimental results show that high-quality gDNA with an average concentration of 50.45 ng/microL can be extracted from 100 microL of saliva. The detection of a mutated alpha-globin gene associated with alpha-thalassemia-1 of southeast Asian (SEA)-type deletion can be completed within less than 1 h. Moreover, the detection limit of the system is found to be 12.00 pg/microL with a high sensitivity up to 90%. Consequently, the proposed saliva-based miniature system can provide a powerful platform for rapid DNA extraction and detection of genetic diseases.

This paper presents a new integrated microfluidic chip that automatically performs ribonucleic acid (RNA) extraction and reverse transcription (RT) processes. The microfluidic system consists of a microfluidic control module and a magnetic bio-separator. The microfluidic control module can perform pumping and mixing of small amount of fluids and subsequent purification and concentration of RNA samples by incorporating with the magnetic bio-separator consisting of 2-dimension twisted microcoils. Notably, the magnetic bio-separators are developed either to generate the required magnetic field to perform the separation of magnetic beads or to work as a micro-heater to control the temperature field for the following RT process. Experimental results show that the total RNA can be successfully purified and extracted by using magnetic beads and the subsequent RT processing of the RNA can be performed automatically. Total RNA is successfully extracted and purified from T98 cells utilizing the microfluidic system, which is comparable with the conventional methods. The whole automatic procedure of RNA sample extraction only takes 35 min, which is much faster than the conventional method (more than 2 h). As a whole, the developed microfluidic system may provide a powerful platform for rapid RNA extraction and RT processes for further biomedical applications.

The present study reports a new three-dimensional (3D) microfluidic platform capable of rapid isolation and detection of cancer cells from a large sample volume (e.g. ~1 mL) by utilizing magnetic microbead-based technologies. Several modules, including a 3D microfluidic incubator for the magnetic beads to capture cancer cells, a microfluidic control module for sample transportation and a nucleic acid amplification module for genetic identification, are integrated into this microsystem. With the incorporation of surface-modified magnetic beads, target cancer cells can be specifically recognized and conjugated onto the surface of the antibody-coated magnetic microbeads by utilizing a swirling effect generated by the new 3D microfluidic incubator, followed by isolating and purifying the magnetic complexes via the incorporation of an external magnet and a microfluidic control module, which washes away any unbound waste solution. Experimental results show that over 90% of the target cancer cells can be isolated from a large volume of bio-samples within 10 min in the 3D microfluidic incubator. In addition, the expressed genes associated with ovarian and lung cancer cells can also be successfully amplified by using the on-chip nucleic acid amplification module. More importantly, the detection limit of the developed system is found to be 5 × 10(1) cells mL(-1) for the target cancer cells, indicating that this proposed microfluidic system may be adapted for clinical use for the early detection of cancer cells. Consequently, the proposed 3D microfluidic system incorporated with immunomagnetic beads may provide a promising automated platform for the rapid isolation and detection of cancer cells with a high sensitivity.

This study presents an integrated microfluidic system capable of automatically performing four reversetranscription polymerase chain reaction (RT-PCR) processes simultaneously for fast diagnosis of aquacultural diseases. This system integrates micro temperature control modules and a microfluidic control module. The micro temperature control modules have micro temperature sensors and array-type micro heaters that maintain precise and uniform temperature conditions for the RT-PCR processes. The microfluidic control module can automatically transport samples and reagents by using pneumatic micropumps, microvalves and microchannels. Moreover, by using random primers in the reverse-transcription (RT) process, the chip design is simplified and the consumption of RT products in the subsequent multiple polymerase chain reactions (PCR) is also minimized. After sample transport between the RT chamber and the PCR chambers is finished, the PCR process is then performed to amplify

The current study presents a new integrated microfluidic chip for rapid ribonucleic acid (RNA) purification, extraction and reverse transcription (RT) in an automatic fashion. The miniature system consists of two individual functional devices including a two-way microfluidic control module and a magnetic field/temperature control module. The functional microfluidic control module can perform pumping, mixing, purification and concentration of the RNA samples by incorporating with the magnetic bio-separator consisting of 2-dimension twisted microcoils. Notably, the magnetic bio-separators are developed either to perform the separation of magnetic beads or to control the temperature field for the subsequent RT process. Experimental results showed that the total RNA was successfully purified and extracted by the magnetic beads, and the subsequent RT process of RNA was completed automatically. As a whole, the developed system may provide a powerful platform for biomedical application and biological analysis.