Sensitive and visual detection of adenosine by a rationally designed FokI-based biosensing strategy

Adenosine Triphosphate-Triggered Release of Macromolecular and Nanoparticle Loads from Aptamer/DNA-Cross-Linked Microcapsules

The synthesis of stimuli-responsive DNA microcapsules acting as carriers for different payloads, and being dissociated through the formation of aptamer-ligand complexes is described. Specifically, stimuli-responsive anti-adenosine triphosphate (ATP) aptamer-cross-linked DNA-stabilized microcapsules loaded with tetramethylrhodamine-modified dextran (TMR-D), CdSe/ZnS quantum dots (QDs), or microperoxidase-11 (MP-11) are presented. In the presence of ATP as trigger, the microcapsules are dissociated through the formation of aptamer-ATP complexes, resulting in the release of the respective loads. Selective unlocking of the capsules is demonstrated, and CTP, GTP, or TTP do not unlock the pores. The ATP-triggered release of MP-11 from the microcapsules enables the MP-11-catalyzed oxidation of Amplex UltraRed by H2O2 to the fluorescent product resorufin.

Programmable Mg2+-dependent DNAzyme switch by the catalytic hairpin DNA assembly for dual-signal amplification toward homogeneous analysis of protein and DNA

The catalytic hairpin DNA assembly-programmed Mg²⁺-dependent DNAzyme switch was proposed for dual-signal amplified detection of protein and DNA.

Low background signal platform for the detection of ATP: when a molecular aptamer beacon meets graphene oxide

A novel molecular aptamer beacon (MAB) was designed by integrating a single-labeled hairpin-shaped aptamer and graphene oxide (GO). The hairpin-shaped aptamer was constructed with anti-ATP aptamer and another five nucleotides added to the 5'-end of the aptamer which are complementary to nucleotides at the 3'-end of the aptamer to form a hairpin-shaped probe. This newly designed MAB which acts as a low background signal platform was used for the ATP detection based on long-range resonance energy transfer (LrRET). In the absence of ATP, the adsorption of the dye-labeled hairpin-shaped aptamer on GO makes the dyes close proximity to GO surface resulting in high efficiency quenching of fluorescence of the dyes. Therefore, the fluorescence of the designed MAB is completely quenched by GO, and the system shows very low background. Conversely, and very importantly, upon the adding of ATP, the quenched fluorescence is recovered significantly, and ATP can be detected in a wide range of 5-2500μM with a detection limit of 2μM and good selectivity. Moreover, when the GO-based MAB was used in cellular ATP assays, preeminent fluorescence signals were obtained, thus the platform of GO-based MAB could be used to detect ATP in real-world samples.

A universal platform for sensitive and selective colorimetric DNA detection based on Exo III assisted signal amplification

Rapid growth of available sequence data has made the detection of nucleic acids critical to the development of modern life sciences. Many amplification methods based on gold nanoparticles and endonuclease for sensitive DNA detection have been developed. However, these approaches require specific target sequence for endonuclease recognition, which cannot be fulfilled in all systems. Replacing the restriction enzyme with a nuclease that does not require any specific recognition sequence may offer a universally adaptable system. Here we have developed a novel homogeneous, colorimetric DNA detection method, which consists of Exo III, a linker DNA, and two DNA-modified gold nanoparticles. This system is simple, low-cost, sensitive and selective. By coupling cyclic enzymatic cleavage and gold nanoparticle for signal amplification, our system provides a colorimetric detection limit of 15 pM, which is 3 orders of magnitude more sensitive than that of a general three-component sandwich assay format. Due to the intrinsic property of Exo III, our method shows excellent detection selectivity for single-base discrimination. More importantly, superior to other methods based on nicking and FokI endonuclease, our target sequence-independent platform is generally applicable for DNA sensing. This new approach could be widely applied to sensitive nucleic acids detection.

Homogeneous analysis: label-free and substrate-free aptasensors

In this Focus Review, we introduce a kind of "label-free" and "substrate-free" (LFSF) aptasensor that carries out the whole sensing process in a homogeneous solution. This means that commonly used covalent label; separation, and immobilization steps in biosensors are successfully avoided, which simplifies the sensing operations to the greatest degree. After brief description about the advantages of aptamers and "LFSF" aptasensors, the main content of the review is divided into fluorescent aptasenors, calorimetric aptasensors, and hemin-aptamer-DNAzyme "LFSF" aptasensors, which are three most widely developed sensing systems in this field. It is hoped that this review can provide an overall scene about how aptamers function as ideal recognition elements in smart analysis.