Laser induced disruption of bacterial spores on a microchip

All-fiber all-optical quantitative polymerase chain reaction (qPCR)

Quantitative polymerase chain reaction (qPCR), the real-time amplification and measurement of a targeted DNA molecule, has revolutionized the biological sciences and is routinely applied in areas such as medical diagnostics, forensics, and agriculture. Despite widescale use of qPCR technology in the lab, the availability of low-cost and high-speed portable systems remains one of the barriers to routine in-field implementation. Here we propose and demonstrate a potential solution using a photonics-based qPCR system. By using an all-optical approach, we achieve ultra-fast temperature response with real-time temperature feedback using nanoliter scale reaction volumes. The system uses a microcavity to act as a nanoliter scale reaction vessel with a laser-driven and optically monitored temperature cycling system for ultrafast thermal cycling and incorporates an all-fiber fluorescence excitation/detection system to achieve real-time, high sensitivity fluorescence monitoring of the qPCR process. Further, we demonstrate the potential of the system to operate as a label-free qPCR system through direct optical measurement of the sample refractive index. Due to advantages in portability and fabrication simplicity, we anticipate that this platform technology will offer a new strategy for fundamental techniques in biochemistry applications, such as point-of-care and remote diagnostics.

Emerging microfluidic devices for cell lysis: a review

Intracellular components containing information about genetic and disease characteristics are key substances to clinical diagnostics. Cell lysis is therefore a crucial step for efficient extraction and the subsequent analysis of intracellular components. With the advent of advanced manufacturing techniques, a number of micro systems have been proposed and applied for manipulating cells on chips. In this paper, we review emerging microfluidic devices for cell lysis. Different lysis mechanisms and related techniques are compared. The technical details, advantages, and limitations of various microfluidic devices are discussed.

Next revolution in the molecular theranostics of infectious diseases: microfabricated systems for personalized medicine

The molecular diagnosis of infectious diseases is currently going through a revolution sustained by the regulatory approval of amplification tests that have been shown to be equivalent or superior to existing gold standard methods. The recent approval of a microarray system for the pharmacogenomic profiling of cytochrome P450-mediated drug metabolism is paving the way to novel, rapid, sensitive, robust and economical microfabricated systems for point-of-care diagnostics, which are utilized closer and closer to the patient's bedside. These systems will enable the multiparametric genetic evaluation of several medical conditions, including infectious diseases. This forecoming revolution will position molecular theranostics in a broader integrated view of personalized medicine, which exploits genetic information from microbes and human hosts to optimize patient management and disease treatment.

Fast spore breaking by superheating

Here we present the results of Bacillus subtilis spores breaking using superheating. The spore sample was pumped through the open-ended capillary tube mounted across the heated zone. We investigated the influence of temperature in the range 120-180 °C. The heat exposure was controlled by the length of the heated zone, the inner diameter of the capillary and the sample flow rate. We found that spore treatment above 120 °C resulted in the release of DNA within 20 s.

Validation of a centrifugal microfluidic sample lysis and homogenization platform for nucleic acid extraction with clinical samples

The applications of microfluidic technologies in medical diagnostics continue to increase, particularly in the field of nucleic acid diagnostics. While much attention has been focused on the development of nucleic acid amplification and detection platforms, sample preparation is often taken for granted or ignored all together. Specifically, little or no consideration is paid to the development of microfluidic systems that efficiently extract nucleic acids from biological samples. Here, a centrifugal microfluidic platform for mechanical sample lysis and homogenization is presented. The system performs sample lysis through a magnetically actuated bead-beating system followed by a centrifugal clarification step. The supernatant is then transferred for extraction using a unique siphon. Several other new microfluidic functions are implemented on this centrifugal platform as well, including sample distribution, a unique hydraulic capillary valve, and self-venting. Additionally, the improved system has features with a small footprint designed specifically for integration with further downstream processing steps. Biological validation of the platform is performed using Bacillus subtilis spores and clinical samples (nasopharyngeal aspirates) for respiratory virus detection. The platform was found to be as efficient as in-tube bead-beating lysis and homogenization for nucleic acid extraction, and capable of processing 4 samples in batch to near PCR-ready products in under 6 min.

Microchip-based one step DNA extraction and real-time PCR in one chamber for rapid pathogen identification

Optimal detection of a pathogen present in biological samples depends on the ability to extract DNA molecules rapidly and efficiently. In this paper, we report a novel method for efficient DNA extraction and subsequent real-time detection in a single microchip by combining laser irradiation and magnetic beads. By using a 808 nm laser and carboxyl-terminated magnetic beads, we demonstrate that a single pulse of 40 seconds lysed pathogens including E. coli and Gram-positive bacterial cells as well as the hepatitis B virus mixed with human serum. We further demonstrate that the real-time pathogen detection was performed with pre-mixed PCR reagents in a real-time PCR machine using the same microchip, after laser irradiation in a hand-held device equipped with a small laser diode. These results suggest that the new sample preparation method is well suited to be integrated into lab-on-a-chip application of the pathogen detection system.