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

Abstract

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.

Paperfluidic Chip Device for Small RNA Extraction, Amplification, and Multiplexed Analysis

“…A paper-based analytical platform has received increasing concerns for the development of POC diagnostics, owing to its speedy assay, small sample volume, cost-effectiveness, and user-friendly operation. − As nucleic acid testing mainly involves sample preparation, amplification, and detection procedures, attention is turning to the development of paper-based analytical techniques that integrated extraction and amplification steps to the detection system . In recent years, much progress have been made in the field of paper-based devices for DNA determination .…”

“…9−12 As nucleic acid testing mainly involves sample preparation, amplification, and detection procedures, attention is turning to the development of paper-based analytical techniques that integrated extraction and amplification steps to the detection system. 13 In recent years, much progress have been made in the field of paper-based devices for DNA determination. 14 Whitesides et al developed a "paper machine", incorporating fast technology analysis (FTA, cardbased) DNA extraction, then in situ amplification and fluorescent detection by sliding the device.…”

Self-contained microfluidic systems: a review

“…In addition to hand-powered twist valves, presented in the previous example, 19 the manual sliding of chambers from one part of the microfluidic chip to another has been demonstrated as an effective way to initiate and control the desired assays. 88 In this work, the serial sliding of the chamber between the loading, PCR amplification, and immune-chromatographic strip modules of the microchip facilitates the multiplexed colourimetric detection of pathogenic S. aureus and E. coli O157:H7. Application of hand-powered mechanisms is not limited to flow driving and control, and can be used for centrifugal separation of plasma from the whole blood, as demonstrated by Wong et al 89 using a hand-powered egg beater.…”

Key Role of Ionic Hydrogen Bonding in Nonspecific Protein Adsorption on a Hydrophobic Surface

“…Various materials such as silicon, glass, poly­(methyl methacrylate) (PMMA), polydimethyl­siloxane (PDMS), polystyrene (PS), polycarbonate (PC), cyclic olefin copolymers (COC), and poly­(vinyl chloride) (PVC) have been applied frequently in fabricating microfluidic chips. Recently, microfluidic chips with various functional elements fabricated in different materials have been extensively explored to perform sophisticated multistep biochemical assays within a single device, allowing for real sample-in–answer-out analysis of complicated biological samples such as whole blood, ,, saliva, and body fluids. − Compared with conventional techniques, integrated microfluidic chips can achieve highly sensitive, high-throughput, and low-cost biological and biomedical analyses with small volumes in a short time. ,,− However, proteins from complicated biological samples strongly interact with the channel wall of microfluidic chips, leading to surface biofouling and great decrease in device performance. − Therefore, considerable efforts have been made to develop reliable and reproducible protein-resistant surfaces on various substrate materials, which are basically categorized into physical adsorbed − and covalent modifications. − Generally, covalent modifications are laborious multistep processes and case dependent, whereas physical adsorbed methods have limited capabilities in suppressing nonspecific proteins adsorption. The current approaches are not always suitable for integrated microfluidic chips fabricated in different materials.…”