Advances in biosensing: The CRISPR/Cas system as a new powerful tool for the detection of nucleic acids

Abstract

A main challenge in the development of biosensing devices for the identification and quantification of nucleic acids is to avoid the amplification of the genetic material from the sample by polymerase chain reaction (PCR), which is at present necessary to enhance sensitivity and selectivity of assays. PCR has undoubtedly revolutionized genetic analyses, but it requires careful purification procedures that are not easily implemented in point of care (POC) devices. In recent years, a new strategy for nucleic acid detection based on clustered regularly interspaced short palindromic repeats (CRISPR) and associated protein systems (Cas) seems to offer unprecedented possibilities. The coupling of the CRISPR/Cas system with recent isothermal amplification methods is fostering the development of innovative optical and electrochemical POC devices. In this review, the mechanisms of action of several new CRISRP/Cas systems are reported together with their use in biosensing of nucleic acids.

Keywords: Biosensing; CRISPR/Cas; Electrochemical sensor; Molecular diagnostic; Nucleic acids; Optical sensor.

Graphical abstract

Fig. 1

CRISPR/Cas defense strategy (reprinted by [29] with permission of The American Association for the Advancement of Science).

Fig. 2

Classification of Cas associated proteins (reprinted by [29] with permission of The American Association for the Advancement of Science).

Fig. 3

PCR based molecular diagnostic workflow.

Fig. 4

Biosensing strategy of: a) SHERLOK (reprinted by [62] with permission of The American Association for the Advancement of Science); b) DETECTR (reprinted by [63] with permission of The American Association for the Advancement of Science); c) HOLMES (freely repinted by [64]).

Fig. 5

E-CRISPR detection strategy (reprinted by [74] with permission of Angewandte Chemie International Edition).

Fig. 6

a) Schematic representation of microfluidic electrochemical biosensors. b) Mechanism of detection mediate by Cas13a. (freely repinted by [77]).