Application of Lab-on-Chip for Detection of Microbial Nucleic Acid in Food and Environment

Abstract

Various diseases caused by food-borne or environmental pathogenic microorganisms have been a persistent threat to public health and global economies. It is necessary to regularly detect microorganisms in food and environment to prevent infection of pathogenic microorganisms. However, most traditional detection methods are expensive, time-consuming, and unfeasible in practice in the absence of sophisticated instruments and trained operators. Point-of-care testing (POCT) can be used to detect microorganisms rapidly on site and greatly improve the efficiency of microbial detection. Lab-on-chip (LOC) is an emerging POCT technology with great potential by integrating most of the experimental steps carried out in the laboratory into a single monolithic device. This review will primarily focus on principles and techniques of LOC for detection of microbial nucleic acid in food and environment, including sample preparation, nucleic acid amplification and sample detection.

Keywords: LOC; biosensor; environment; food; isothermal amplification; microorganism enrichment.

FIGURE 1

Schematic diagram of LOC process for nucleic acid detection of food and environmental microorganisms. (A) Sample injection. (B) There are a large number of micro-pumps and micro-valves on the chip to precisely control the flow direction and flow rate of microfluids. (C) Sample preparation including pathogen capture, cell lysis, nucleic acid extraction and purification, etc. The methods of pathogen capture mainly include microsphere, filter or membrane, dielectrophoresis, magnetophoresis, acoustophoresis, etc. This part often needs external electric field, magnetic field, ultrasonic, and its strength is controlled by the controller. (D) Nucleic acid amplification. In addition to traditional PCR, various emerging isothermal nucleic acid amplification techniques have been applied to LOC equipment. The substrate used for nucleic acid amplification is packed into a micro chamber in advance, and the temperature of the reaction process is controlled by a temperature controller. (E) Sample detection devices, primarily sensors. Such as fluorescence sensors, surface plasma resonance (SPR) sensors, surface enhanced Raman scattering (SERS) sensors, electrochemical biosensors. (F) Results are visually displayed on the display.

FIGURE 2

Schematic diagram of loop-mediated isothermal amplification.

FIGURE 3

Schematic diagram of recombinant enzyme polymerase amplification.

FIGURE 4

Schematic diagram of helicase-dependent amplification.

FIGURE 5

Schematic diagram of rolling loop amplification.

FIGURE 6

Schematic diagram of NASBA principle.

FIGURE 7

Schematic diagram of surface plasmon resonance.