Dual-color graphene quantum dots and carbon nanoparticles biosensing platform combined with Exonuclease III-assisted signal amplification for simultaneous detection of multiple DNA targets.

Sensitive and simultaneous detection of multiple biomarkers such as target DNA or proteins using biocompatible materials with good analysis performance remains an important challenge. Herein, we successfully developed a signal "off-on" highly sensitive multiplex detection platform based on the combination of dual-color graphene quantum dots (blue GQDs and green GQDs) modified DNA probes with carbon nanoparticles (CNPs), which is a cheap, effective nonfluorescent quencher to simultaneously quench the fluorescence of both GQDs-DNA probes. The Exo III-assisted sequence-independent target recycling and signal amplification strategy was integrated into this sensing platform, which endows it with high sensitivity towards the multiplex detection of targets DNA. The detection limits of 6.6 pM for HIV and 9.5 pM for HBV were achieved respectively, which is about 60-fold lower than that of traditional unamplified homogeneous fluorescent assay methods. Our proposed multiplex detecting platform is advantageous in both respective and simultaneous detection of multiple targets and can also discriminate perfectly matched targets from mismatched targets in both PBS buffer and 1% human serum samples, demonstrating its potential to be a reliable strategy for highly sensitive simultaneous detection of multiple target genes in practical diagnosis applications.

Programming DNA Tube Circumference by Tile Offset Connection.

DNA tubes with prescribed circumferences are appealing for numerous multidisciplinary applications. The DNA single-stranded tiles (SSTs) assembly method has demonstrated an unprecedented capability for programming the circumferences of DNA tubes in a modular fashion. Nevertheless, a distinct set of SSTs is typically required to assemble DNA tube of a specific circumference, with wider tubes requiring higher numbers of tiles of unique sequences, which not only increases the expense and design complexity but also hampers the assembly yield. Herein, we introduce "offset connection" to circumvent such challenges in conventional SST tube assembly. In this new connection scheme, the boundary SST tiles in an SST array are designed to connect in an offset manner. To compensate for the offset, the SST array has to grow wider until the array can close to form a wide tube with a tolerable degree of twist. Using this strategy, we have successfully assembled DNA tubes with prescribed circumferences consisting of 8, 12, 14, 16, 20, 24, 28, 32, 36, 42, 56, or 70 helices from two distinct sets of SSTs composed of 19×4 or 19×14 tiles.