Integration of nanoparticle cell lysis and microchip PCR for one-step rapid detection of bacteria

Low-voltage electrical cell lysis using a microfluidic device

Cell lysis, where cellular material is released, is the basis for the separation and purification of cell contents, biochemical analysis, and other related experiments. It is also a key step in molecular, real-time, and cancer diagnoses as well as in the drug screening of pathogens. The current methods of lysing cells have several limitations, such as damage to the activity of cellular components, the need for a large number of cell samples, time-consuming processes, and the danger of high voltage. Therefore, a simple, fast, and efficient method for the manipulation of micro-volume cells or for single cell lysis is significant for further scientific research and practical application. In this study, a new low-voltage controllable method for cell lysis was established, and a corresponding microfluidic chip was developed. Simple, efficient and rapid micro-volume cells and single cell lysis were successfully achieved under a low-voltage alternating current with a voltage of 16 V_p-p and frequency of 10 kHz. The lysis process was investigated in detail by separately labelling the whole cell, cytoplasm, and nucleus using fluorescent proteins, which indicated that the whole cell was completely lysed. Analysis of voltage and frequency effects revealed that a higher voltage and optimized frequency enhanced the cell lysis efficiency. The presented study provides a new strategy for the lysis of micro-volume cells or a single cell, which is valuable for on-chip real-time diagnostics and point of care (POC) applications.

Gold Nanorod-based Photo-PCR System for One-Step, Rapid Detection of Bacteria

The polymerase chain reaction (PCR) has been an essential tool for diagnosis of infectious diseases, but conventional PCR still has some limitations with respect to applications to point-of-care (POC) diagnostic systems that require rapid detection and miniaturization. Here we report a light-based PCR method, termed as photo-PCR, which enables rapid detection of bacteria in a single step. In the photo-PCR system, poly(enthylene glycol)-modified gold nanorods (PEG-GNRs), used as a heat generator, are added into the PCR mixture, which is subsequently periodically irradiated with a 808-nm laser to create thermal cycling. Photo-PCR was able to significantly reduce overall thermal cycling time by integrating bacterial cell lysis and DNA amplification into a single step. Furthermore, when combined with KAPA2G fast polymerase and cooling system, the entire process of bacterial genomic DNA extraction and amplification was further shortened, highlighting the potential of photo-PCR for use in a portable, POC diagnostic system.

Microfluidic method of pig oocyte quality assessment in relation to different follicular size based on lab-on-chip technology

Since microfollicular environment and the size of the follicle are important markers influencing oocyte quality, the aim of this study is to present the spectral characterization of oocytes isolated from follicles of various sizes using lab-on-chip (LOC) technology and to demonstrate how follicle size may affect oocyte quality. Porcine oocytes (each, n = 100) recovered from follicles of different sizes, for example, from large (>5 mm), medium (3–5 mm), and small (<3 mm), were analyzed after preceding in vitro maturation (IVM). The LOC analysis was performed using a silicon-glass sandwich with two glass optical fibers positioned “face-to-face.” Oocytes collected from follicles of different size classes revealed specific and distinguishable spectral characteristics. The absorbance spectra (microspectrometric specificity) for oocytes isolated from large, medium, and small follicles differ significantly (P < 0.05) and the absorbance wavelengths were between 626 and 628 nm, between 618 and 620 nm, and less than 618 nm, respectively. The present study offers a parametric and objective method of porcine oocyte assessment. However, up to now this study has been used to evidence spectral markers associated with follicular size in pigs, only. Further investigations with functional-biological assays and comparing LOC analyses with fertilization and pregnancy success and the outcome of healthy offspring must be performed.