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

• A fluorescent method was developed for human immunodeficiency virus type 1 DNA assay.
• The method was based on a label-free DNA templated Ag NCs fluorescent probe.
• The DNA templated Ag NCs fluorescent probe was separating from recognition process.

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 2.9×10−10 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.

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