Table 3.

New technologies for exosomal nucleic acid detection

Methods	Exosome sources	Sample volume	Nucleic acids	Detection mechanism	Advantages	Disadvantages	Ref.
Droplet digital PCR	Urine	2 mL	miRNA; gene variation	Nucleic acid amplification of droplets in an oil emulsion	Absolute quantification; small sample volume; high accuracy and sensitivity;	High-cost; limited throughout; complex operation	[163]
	Cerebrospinal fluid of GBM patients	1 mL	IDH1 mutation				[164]
	Plasma samples of HCC patients and control cohorts	90 μL	HCC-specific mRNA				[61]
	Cancer cell lines and patient plasma	2 μL	GAPDH mRNA				[165]
	Human plasma		miR-15a-5p				[40]
	Human plasma		PGR mRNA; ESR1 mRNA; ERBB2 mRNA				[120]
	Clinical blood	1.5 mL	EV-lncRNA of SLC9A3-AS1 and PCAT6				[166]
	Serum	100 μL	circHIPK3 and circSM ARCA5				[167]
Molecular beacons	Cancer cells and human serums	35 μL	miRNA-21	Fluorescent, enzyme-labeled oligonucleotide probes identifying and detecting nucleic acid with complementary sequences	High specificity, simplicity; low background fluorescence; rapid detection	High-cost; limited throughout	[122]
	Breast cancer cell line and human plasma		miR-21; miR-375; and miR-27a				[121]
	Prostate cancer cells and human urine		miRNA-375 and miRNA-574-3p				[168]
	Human plasma	10 μL	miR-1246				[169]
	RBC-derived EVs		miRNA-451a				[170]
	PCA cell		miR-21				[151]
DNA tetrahedron probe	Serum		miR-21	Leverage localized reaction and cascade amplification	High specificity and sensitivity	High-cost	[171]
	Plasma	1 mL	miR-1246; miR-221; miR-375; miR-21				[172]
SPR Detection	Pancreatic cancer cells and plasma	50 μL	miR-10b	The change of dielectric constant caused by molecule adsorption on the heavy metal film	High specificity and sensitivity; label-free	Nonspecific adsorption	[173]
	Plasma		miRNA				[123]
	Mouse serum		miR-10b				[174]
Single Vesicle Analysis	Serum		hsa-miRNA-21	Single-vesicle imaging	Direct visualization; acknowledgement of heterogeneity at the single-vesicle level	Nonspecific adsorption	[119]
Thermophoretic Detection	Serum	0.5 μL	miRNA	Nanoflare induced amplified fluorescence signal	Without the need for EV pre-isolation; high sensitivity; rapid detection; low cost		[175]
CRISPR/Cas-assisted detection	Plasma	500 μL	miRNA-21; miRNA-221; miRNA-222	CRISPR/Cas9	High sensitivity and specificity		[176]

PGR Progesterone receptor, ESR1 Estrogen receptor 1, ERBB2 erb-b2 receptor tyrosine kinase 2, PCAT6 Prostate cancer associated transcript 6