•Highly efficient assembly of DNA nanostructure on nanopore membrane utilizing hybridization chain reaction.•A label-free nanopore biosensor has been developed utilizing hybridization chain reaction as signal amplification strategy.•Significant improvement of sensitivity has been achieved compared to conventional amplification-free nanopore biosensor.•It may provide a new paradigm for the design of nanopore biosensor utilizing nucleic acid-based amplification strategy.A label-free nanopore biosensor for detection of DNA target is proposed utilizing hybridization chain reaction (HCR) strategy for signal amplification. The DNA target triggered HCR to form large DNA nanostructure inside the nanopore and out the nanopore membrane, which inducing the ionic current decrease effectively due to the blockage of the nanopore. The developed method achieves a desirable sensitivity of 30 fM with a wide linear dynamic range from 0.1 to 10 pM and demonstrated good application for real sample analysis. This work has great potential to be applied in the early diagnosis of gene-related diseases and provide a new paradigm for label-free nucleic acid amplification strategy in ultrasensitive nanopore biosensor.A label-free nanopore biosensor has been developed for the detection of DNA target with high sensitivity and specificity utilizing hybridization chain reaction as signal amplification strategy.Download high-res image (135KB)Download full-size image

Based on the aggregation of gold nanoparticles (AuNPs) induced by the acetylcholinesterase-catalyzed hydrolysis reaction, we have developed a novel highly sensitive enzyme mediated AuNP assembly based colorimetric method for the ultrasensitive detection of hepatitis C virus antibody (anti-HCV). The change of the AuNP color could be observed with the naked eye directly, and the detection limit achieved was as low as 10−13 g mL−1 anti-HCV, which was an improvement of 3 orders of magnitude compared to the conventional ELISA method. The developed method is sensitive and affordable, which will be useful for HCV disease monitoring and control in remote areas and resource-constrained countries.

Graphitic C3N4 (g-C3N4) nanosheets provide an attractive option for bioprobes and bioimaging applications. Utilizing highly fluorescent and water-dispersible ultrathin g-C3N4 nanosheets, a highly sensitive, selective and label-free biosensor has been developed for ALP detection for the first time. The developed approach utilizes a natural substrate of ALP in biological systems and thus affords very high catalytic efficiency. This novel biosensor is demonstrated to enable quantitative analysis of ALP in a wide range from 0.1 to 1000 U L−1 with a low detection limit of 0.08 U L−1, which is among the most sensitive assays for ALP. It is expected that the developed method may provide a low-cost, convenient, rapid and highly sensitive platform for ALP-based clinical diagnostics and biomedical applications.

Efficient tools for profiling DNA methylation in specific genes are essential for epigenetics and clinical diagnostics. Current DNA methylation profiling techniques have been limited by inconvenient implementation, requirements of specific reagents, and inferior accuracy in quantifying methylation degree. We develop a novel mass spectrometry method, target fragmentation assay (TFA), which enable to profile methylation in specific sequences. This method combines selective capture of DNA target from restricted cleavage of genomic DNA using magnetic separation with MS detection of the nonenzymatic hydrolysates of target DNA. This method is shown to be highly sensitive with a detection limit as low as 0.056 amol, allowing direct profiling of methylation using genome DNA without preamplification. Moreover, this method offers a unique advantage in accurately determining DNA methylation level. The clinical applicability was demonstrated by DNA methylation analysis using prostate tissue samples, implying the potential of this method as a useful tool for DNA methylation profiling in early detection of related diseases.

Graphitic C3N4 (g-C3N4) nanosheets are a type of emerging graphene-like carbon-based nanomaterials with high fluorescence and large specific surface areas that hold great potential for biosensor applications. However, current g-C3N4 based biosensors have prevailingly been limited to coordination with metal ions, and it is of great significance to develop new designs for g-C3N4 nanosheets based biosensors toward biomarkers of general interest. We report the development of a novel g-C3N4 nanosheet-based nanosensor strategy for highly sensitive, single-step and label-free detection of tyrosinase (TYR) activity and its inhibitor. This strategy relies on the catalytic oxidation of tyrosine by TYR into melanin-like polymers, which form a nanoassembly on the g-C3N4 nanosheets and quench their fluorescence. This strategy was demonstrated to provide excellent selectivity and superior sensitivity and to enable rapid screening for TYR inhibitors. Therefore, the developed approach might create a useful platform for diagnostics and drugs screening for TYR-based diseases including melanoma cancer.

Trinucleotide repeat detection is important for understanding the molecular mechanisms of repeat size mutation and clinical diagnosis. In this study, a novel target fragment assay (TFA) for trinucleotide repeat length detection was developed using magnetic capture and acidic degradation of target polymerase chain reaction amplicons followed by mass spectrometry detection. The developed TFA enables accurate, rapid, and sensitive detection of the trinucleotide repeat lengths and provides a new paradigm for identifying nucleic acid sequence variations. Detection of the CAG repeat length associated with Huntington's disease was successfully demonstrated utilizing the developed TFA.

Gold nanoparticles (AuNPs) have been extensively used in optical biosensing and bioimaging due to the unique optical properties. Biological applications including biosensing and cellular imaging based on optical properties of AuNPs will be reviewed in the paper. The content will focus on detection principles, advantages and challenges of these approaches as well as recent advances in this field.

A novel, highly sensitive split aptamer mediated endonuclease amplification strategy for the construction of aptameric sensors is reported.

A novel ICP MS DNA assay based on lanthanide labels and hybridization chain reaction amplification has been developed. This approach utilizes an enzyme-free amplification and can be operated under mild conditions. The developed assay exhibits desirable sensitivity and is suitable for multiple DNA target analysis because a general DNA hybridization approach is applied to capture target DNA. Considering lanthanide labels and ICP-MS have excellent ability in high-level multiplexing analysis, this approach holds great potential for practical use in quantitative determination of DNA targets for future clinical applications.

A novel surface enhanced Raman scattering (SERS) based assay using a formaldehyde-selective reactive probe for sensitive detection of activity of histone demethylases (HDMs) by direct observation of by-product formaldehyde was reported.

A novel homogeneous fluorescence assay strategy for highly sensitive detection of thymine DNA glycosylase (TDG) enzyme activity based on the exonuclease-mediated signal amplification reaction was reported.

A novel surface enhanced Raman scattering (SERS) based assay using a formaldehyde-selective reactive probe for sensitive detection of activity of histone demethylases (HDMs) by direct observation of by-product formaldehyde was reported.

A novel homogeneous fluorescence assay strategy for highly sensitive detection of thymine DNA glycosylase (TDG) enzyme activity based on the exonuclease-mediated signal amplification reaction was reported.

A novel, highly sensitive split aptamer mediated endonuclease amplification strategy for the construction of aptameric sensors is reported.

A novel ICP MS DNA assay based on lanthanide labels and hybridization chain reaction amplification has been developed. This approach utilizes an enzyme-free amplification and can be operated under mild conditions. The developed assay exhibits desirable sensitivity and is suitable for multiple DNA target analysis because a general DNA hybridization approach is applied to capture target DNA. Considering lanthanide labels and ICP-MS have excellent ability in high-level multiplexing analysis, this approach holds great potential for practical use in quantitative determination of DNA targets for future clinical applications.