Hydrogels for Efficient Multiplex PCR

Multiplex PCR simultaneously detects several different DNA targets in a given sample and has, therefore, gained considerable interest for use in examining a genetic target whose number rapidly increases in a single phenotype. Conventional real-time PCR lacks sufficient multiplex capacity, as the limited number of color channels restricts the number of simultaneously detectable targets to six. On the contrary, DNA-based hydrogel microparticles immobilized with primers provide outstanding multiplex capacity, as they can encode for various patterns with a level of coding capacity high enough to identify ≥ 10⁵ targets. Moreover, hydrogel microparticles comprising polyethylene glycol can be made extremely porous, as it is easy to control their porosity and hydrophilic properties. Their high compatibility for aqueous biochemical reactions also ensures an environment and efficiency similar to amplification reactions occurring in aqueous media. The applicability of DNA-based encoded hydrogel microparticles with fixed primers has been widely proven through various hydrogel particle-based bioassays. This review focuses on the advancements in diverse approaches for an efficient multiplex PCR based on such microparticles. Herein, multiple strategies for constructing and encoding a “hydrogel” are described. Moreover, various methods for an efficient hydrogel PCR and the latest developments regarding multiple forms of bioassays that utilize hydrogel PCR are illustrated using selected examples. Lastly, this review provides insights into the prospects for encoded hydrogel microparticles and the challenges for their application.