Antibody-Responsive Ratiometric Fluorescence Biosensing of Biemissive Silver Nanoclusters Wrapped in Switchable DNA Tweezers

Abstract

Exploring the ratiometric fluorescence biosensing of DNA-templated biemissive silver nanoclusters (AgNCs) is significant in bioanalysis, yet the design of a stimuli-responsive DNA device is a challenge. Herein, using the anti-digoxin antibody (anti-Dig) with two identical binding sites as a model, a tweezerlike DNA architecture is assembled to populate fluorescent greenand red-AgNCs (g-AgNCs and r-AgNCs), aiming to produce a ratio signal via specific recognition of anti-Dig with two haptens (DigH). To this end, four DNA probes are programmed, including a reporter strand (RS) dually ended with a g-/r-AgNC template sequence, an enhancer strand (ES) tethering two same G-rich tails (G18), a capture strand (CS) labeled with DigH at two ends, and a help strand (HS). Initially, both g-AgNCs and r-AgNCs wrapped in the intact RS are nonfluorescent, whereas the base pairing between RS, ES, CS, and HS resulted in the construction of DNA mechanical tweezers with two symmetric arms hinged by a rigid "fulcrum", in which g-AgNCs are lighted up due to G18 proximity ("green-on"), and r-AgNCs away from G18 are still dark ("red-off"). When two DigHs in proximity recognize and bind anti-Dig, the conformation switch of these tweezers resultantly occurs, taking g-AgNCs away from G18 for "green-off" and bringing r-AgNCs close to G18 for "red-on". As such, the ratiometric fluorescence of r-AgNCs versus g-AgNCs is generated in response to anti-Dig, achieving reliable quantization with a limit of detection at the picomolar level. Based on the fast stimulated switch of unique DNA tweezers, our ratiometric strategy of dual-emitting AgNCs would provide a new avenue for a variety of bioassays.

Sensing beyond Senses: An Overview of Outstanding Strides in Architecting Nanopolymer-Enabled Sensors for Biomedical Applications

“…As the size of most biological molecules and cell organelles fall within the nanometer scale, the extension of nanotechnology to diagnostics has brought revolutionary changes in the form of biomolecular detectors [ 80 ] DNA nanomachines [ 81 ], imprinted polymers [ 82 ], DNA tweezers [ 83 ], and enabling biological tests [ 84 ] to be more sensitive and quicker, which is most demanded in clinical laboratories. Nanomaterials, due to their smaller size, can drastically enhance one-to-one interaction across the analyte and signal-generating target biomolecules.…”

Highly Efficient Quadruped DNA Walker Guided by Ordered DNA Tracks for Rapid and Ultrasensitive Electrochemical Detection of miRNA-21

“…In the past few decades, researchers have designed many highly complicated and powerful DNA molecular machines that could implement specific functions on a nanoscale, for example, DNA robots, − DNA tweezers, − DNA walkers, − etc. Among the various kinds of molecular machines, the DNA walker, a novel dynamic nanomachine, − which could walk along designed DNA tracks to guarantee transport of cargoes with the help of driving forces (the driving forces including strand displacement reaction (SDR), protein enzyme/DNAzyme reaction, and environmental stimuli), has attracted more and more eyes to explore in sensing systems, , bioimaging, − molecular computing, cargo delivery, programmed synthesis, logic gates devices, and so on.…”

Target Deoxyribonucleic Acid-Recycled Lighting-Up Amplifiable Ratiometric Fluorescence Biosensing of Bicolor Silver Nanoclusters Hosted in a Switchable Deoxyribonucleic Acid Construct

“…19 For example, switchable tweezer-shaped DNA devices have been reported to be capable of capturing, holding, and releasing a molecular object or implementing mechanical closing or opening motion in response to a targeting trigger. 12,20 Because of multiple information encoded in the base-sequence of nucleic acids, DNA nanostructures can be directionally reconfigured through strand displacement induced by external stimuli, such as fuels, changed pH, or temperature, which are specific modules of interest. 12,13,21,22 Benefiting from structural programmability, diversity, and flexibility, an arsenal of progresses with dynamic DNA nanotechnology has provided promising means to realize tunable and adaptive functions at the nanometer scale.…”

“…12,20 Because of multiple information encoded in the base-sequence of nucleic acids, DNA nanostructures can be directionally reconfigured through strand displacement induced by external stimuli, such as fuels, changed pH, or temperature, which are specific modules of interest. 12,13,21,22 Benefiting from structural programmability, diversity, and flexibility, an arsenal of progresses with dynamic DNA nanotechnology has provided promising means to realize tunable and adaptive functions at the nanometer scale. Among them, an interesting example might be anchoring the template of emitting AgNCs as a signal reporter in subtly designed functional units or domains of DNA secondary structures, e.g., dimers or hairpins.…”

“…26,27 Most recently, we reported a ratiometic strategy of dual-emitting AgNCs hosted in a tweezer-like DNA architecture, where two G-rich tails were tethered to turn on their fluorescence when approaching to clusters. 12 Based on hybridizing or recognizing induced signal changes of bicolor AgNCs stabilized in one assembled DNA entity, as a result, these findings greatly enrich the accessibility and possibility to construct ratiometric systems but have seldom been used.…”