The Boolean logic tree of molecular self-assembly system based on cobalt oxyhydroxide nanoflakes for three-state logic computation, sensing and imaging of pyrophosphate in living cells and in vivo

Development of cobalt oxyhydroxide-aptamer-based upconversion sensing nano-system for the rapid detection of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a common pathogen that is dangerous to humans' health. Herein, a novel upconversion fluorescent biosensor based on fluorescence resonance energy transfer from aptamer-labeled upconversion nanoparticles (UCNPs-apt) as donor and cobalt oxyhydroxide (CoOOH) nanosheets as acceptor was designed to detect S. aureus in complex matrices. The principle of the work relies on fluorescence resonance energy transfer as UCNPs-apt can self-assemble on CoOOH nanosheet surfaces by van der Waals forces to effectively quench the fluorescence. When S. aureus was added, the aptamer was able to preferentially capture the target, resulting in the dissociation of donor and acceptor and the recovery of fluorescence. The structure and morphology of the nanostructures were assigned in detail by a series of characterizations, and the energy transfer mechanism was evaluated by time-resolved lifetime measurements. Under the optimal conditions, a linear calibration plot was obtained in a concentration range of 45-4.5 × 10⁶ CFU/mL with a limit of detection of 15 CFU/mL. In addition, the proposed biosensor was used for S. aureus detection in real samples (e.g., pork, beef), and the detection result showed no significant difference (p > 0.05) compared with the conventional plate count approach. Hence, the fabricated biosensor holds a potential application for S. aureus in food analysis and public health.

Aggregation-induced responses (AIR) of 2D-derived layered nanostructures enable emerging colorimetric and fluorescence sensors

Layered nanostructures (LNs), including two-dimensional nanosheets, nanoflakes, and planar nanodots, show large surface-to-volume ratios, unique optical properties, and desired interfacial activities. LNs are highly promising as alternative probes and platforms due to numerous merits, e.g. signal amplification, improved recognition ability, and anti-interference capacity, for emerging sensing applications. Significantly, when stimuli-responsive aggregation occurs, the modified LNs show engineered morphologies, attractive optical absorption and fluorescence characteristics, which are remarkably programmable. On the basis of the altered aggregation behaviours of LNs, as well as their modulated physical and chemical characteristics, a series of novel sensing assays exhibiting enhanced sensitivity, simple operation, multiple functions, and improved anti-interference capacity are reported, contributing to both point-of-care testing and high-throughput measurements. Herein, the aggregation-induced response sensing strategies of LNs are comprehensively summarized with the classification of materials and variation of aggregated routes aiming at understanding dimension-dependent features, expanding nanoscale biosensor applications, and addressing key issues in disease diagnosis and environmental analysis.

One-pot synthesis of luminol–gallium nanoassemblies and their peroxidase-mimetic activity for colorimetric detection of pyrophosphate

Luminol–Ga nanoassemblies exhibit peroxidase-mimetic activity. Colorimetric detection of PPi is developed owing to the formation of a complex between PPi and Ga³⁺.

Game Theory in Molecular Nanosensing System for Rapid Detection of Hg2+ in Aqueous Solutions

Game theory—the scientific study of interactive, rational decision making—describes the interaction of two or more players from macroscopic organisms to microscopic cellular and subcellular levels. Life based on molecules is the highest and most complex expression of molecular interactions. However, using simple molecules to expand game theory for molecular decision-making remains challenging. Herein, we demonstrate a proof-of-concept molecular game-theoretical system (molecular prisoner’s dilemma) that relies on formation of the thymine–Hg2+–thymine hairpin structure specifically induced by Hg2+ and fluorescence quenching and molecular adsorption capacities of cobalt oxyhydroxide (CoOOH) nanosheets, resulting in fluorescence intensity and distribution change of polythymine oligonucleotide 33-repeat thymines (T33). The “bait” molecule, T33, interacted with two molecular players, CoOOH and Hg2+, in different states (absence = silence and presence = betrayal), regarded as strategies. We created conflicts (sharing or self-interest) of fluorescence distribution of T33, quantifiable in a 2 × 2 payoff matrix. In addition, the molecular game-theoretical-system based on T33 and CoOOH was used for sensing Hg2+ over the range of 20 to 600 nM with the detection limit of 7.94 nM (3σ) and for determination of Hg2+ in pond water. Inspired by the proof-of-concept for molecular game theory, various molecular decision-making systems could be developed, which would help promote molecular information processing and generating novel molecular intelligent decision systems for environmental monitoring and molecular diagnosis and therapy.