In this work, we report the design of a novel graphene-based molecular beacon (MB) that could sensitively and selectively detect specific DNA sequences. The ability of water-soluble graphene oxide (GO) to differentiated hairpin and dsDNA offered a new approach to detect DNA. We found that the background fluorescence of MB was significantly suppressed in the presence of GO, which increased the signal-to-background ratio, hence the sensitivity. Moreover, the single-mismatch differentiation ability of hairpin DNA was maintained, leading to high selectivity of this new method.

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We herein report a power-free microfluidic chip for fluorescent DNA detection with high single-nucleotide polymorphism discrimination, using a DNA intercalator and graphene oxide.

The ability to acquire images under low-light conditions is critical for many applications. However, to date, strategies toward improving low-light imaging primarily focus on developing electronic image sensors. Inspired by natural scotopic visual systems, we adopt an alloptical method to significantly improve the overall photosensitivity of imaging systems. Such optical approach is independent of, and can effectively circumvent the physical and material limitations of, the electronics imagers used. We demonstrate an artificial eye inspired by superposition compound eyes and the retinal structure of elephantnose fish. The bioinspired photosensitivity enhancer (BPE) that we have developed enhances the image intensity without consuming power, which is achieved by three-dimensional, omnidirectionally aligned microphotocollectors with parabolic reflective sidewalls. Our work opens up a previously unidentified direction toward achieving high photosensitivity in imaging systems.bioinspired optical devices | low-light imaging | microopto-electromechanical systems | femtosecond laser micromachining | low aberrations

This work reports the development of a new molecular beacon-based junction sensing system with highly sensitive DNA detection and a strong capability to identify SNPs. The single linear probe typically labels the midsection of the oligonucleotide, but our next-generation junction sensing system uses a hairpin-structured MB with labels on each end of the oligonucleotide to maintain the cleaving activity of our newly designed ssDNA-cleaved endonuclease, Nt.BbvCI, rather than the typical dsDNA-cleaved endonuclease. These design improvements guarantee a true and efficient target-triggered enzymatic recycling amplification process in our sensing system. They also afford a faster and more sensitive response toward target DNA than the first-generation junction sensing system.

The accurate detection of glucose at cellular level remains a big challenge. In this study, a signal amplification strategy mediated by silver nanocube (AgNC), glucose oxidase (GOx), and silver ion fluorescence probe (denoted as AgNC–GOx/Ag+-FP) is proposed for amplified intracellular glucose detection. The AgNC is oxidized into Ag+ by H2O2 generated from GOx-catalyzed glucose oxidation reaction, and Ag+ remarkably enhances the red fluorescence of Ag+-FP. Our results show that AgNC–GOx/Ag+-FP is highly sensitive and specific to glucose and H2O2. Afterward, the feasibility of using AgNC–GOx/Ag+-FP to detect intracellular glucose is verified in five different cell lines. In summary, a sensitive and specific fluorescence amplification strategy has been developed for intracellular glucose detection.

Magnetic graphene composites (MGCs), which are composed of magnetic nanoparticles with graphene or its derivatives, played an important role in sensors development. Due to the enhanced electronic properties and the synergistic effect of magnetic nanomaterials and graphene, MGCs could be used to realize more efficient sensors such as chemical, biological, and electronic sensors, compared to their single component alone. In this review, we first reviewed the various routes for MGCs preparation. Then, sensors based on MGCs were discussed in different groups, including optical sensors, electrochemical sensors, and others. At the end of the paper, the challenges and opportunities for MGCs in sensors implementation are also discussed.

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