Abstract: Disclosed is an adaptor for sequencing DNAs at ultratrace levels and its uses. The adaptor contains, from 5?terminus to 3?terminus, a Tag sequence, PolyNs, a first stem sequencing, a first loop sequence, dUTP(s), a second loop sequence, and a second stem sequence, wherein the second stem sequence is complementary to the first stem sequence when read in opposite directions, and the 5?terminus of the adaptor is phosphorylated. The adaptor is designed to form a hairpin structure itself in use and then ligated to a DNA molecule of interest, so that adaptor-adaptor ligation can be effectively avoided, eliminating the inefficient adaptor-DNA ligation problem. Such an adaptor is especially suitable for library construction and sequencing of DNAs at ultratrace levels, laying a good basis for accurate sequencing of ctDNAs.

Abstract: Disclosed is an adaptor for sequencing DNAs at ultratrace levels and its uses. The adaptor contains, from 5?terminus to 3?terminus, a Tag sequence, PolyNs, a first stem sequencing, a first loop sequence, dUTP(s), a second loop sequence, and a second stem sequence, wherein the second stem sequence is complementary to the first stem sequence when read in opposite directions, and the 5?terminus of the adaptor is phosphorylated. The adaptor is designed to form a hairpin structure itself in use and then ligated to a DNA molecule of interest, so that adaptor-adaptor ligation can be effectively avoided, eliminating the inefficient adaptor-DNA ligation problem. Such an adaptor is especially suitable for library construction and sequencing of DNAs at ultratrace levels, laying a good basis for accurate sequencing of ctDNAs.

Abstract: The present invention provides a method and a reagent for enrichment of circulating tumor DNA, the method comprising the steps of mixing a water phase and an oil phase and shaking the mixture to prepare an emulsion PCR reaction system, and performing emulsion PCR amplification, wherein the water phase comprises peripheral blood plasma DNA as template DNA, a forward primer and a reverse primer, dNTPs, a PCR buffer and a DNA polymerase, the peripheral blood plasma DNA having adapter sequences connected to both ends thereof, and the forward primer and the reverse primer being complementary to the adapter sequences at the two ends respectively; separating the water phase from the oil phase following the emulsion PCR amplification to obtain a PCR amplification product in the water phase; and capturing circulating tumor DNA in the PCR amplification product in the water phase by using a probe sequence that specifically binds to the circulating tumor DNA.

Abstract: The present invention provides a method and a reagent for enrichment of circulating tumor DNA, the method comprising the steps of mixing a water phase and an oil phase and shaking the mixture to prepare an emulsion PCR reaction system, and performing emulsion PCR amplification, wherein the water phase comprises peripheral blood plasma DNA as template DNA, a forward primer and a reverse primer, dNTPs, a PCR buffer and a DNA polymerase, the peripheral blood plasma DNA having adapter sequences connected to both ends thereof, and the forward primer and the reverse primer being complementary to the adapter sequences at the two ends respectively; separating the water phase from the oil phase following the emulsion PCR amplification to obtain a PCR amplification product in the water phase; and capturing circulating tumor DNA in the PCR amplification product in the water phase by using a probe sequence that specifically binds to the circulating tumor DNA.