Label-free nucleic acids detection based on DNA templated silver nanoclusters fluorescent probe

Based on DNA templated Ag NCs (DNA/Ag NCs) fluorescent probe, a label-free fluorescent method was developed for the detection of clinical significant DNA fragments from human immunodeficiency virus type 1 (HIV-1) DNA. Firstly, a hairpin probe, containing target DNA recognition sequence and guanine-rich sequence, was designed to hybridize with the target DNA and form a blunt 3'-terminus DNA duplex. Then, exonuclease III (Exo III) was employed to stepwise hydrolyze the mononucleotides from formed blunt 3'-terminus DNA duplex, releasing the target DNA and guanine-rich sequence. Finally, DNA/Ag NCs fluorescent probe was introduced to hybridize with the guanine-rich sequence, leading to an enhanced fluorescence signal for detection. The proposed method could detect as low as 2.9 x 10(-10) mol L-1 HIV-1 DNA and exhibited excellent selectivity against mismatched target DNA. Furthermore, the method possessed perfect recoveries in cells lysate and human serum, showing potential to be used in biological samples. (C) 2015 Elsevier B.V. All rights reserved.