A self-assembled DNA nanostructure as a FRET nanoflare for intracellular ATP imaging

Latest assessment methods for mitochondrial homeostasis in cognitive diseases

Mitochondria play an essential role in neural function, such as supporting normal energy metabolism, regulating reactive oxygen species, buffering physiological calcium loads, and maintaining the balance of morphology, subcellular distribution, and overall health through mitochondrial dynamics. Given the recent technological advances in the assessment of mitochondrial structure and functions, mitochondrial dysfunction has been regarded as the early and key pathophysiological mechanism of cognitive disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, mild cognitive impairment, and postoperative cognitive dysfunction. This review will focus on the recent advances in mitochondrial medicine and research methodology in the field of cognitive sciences, from the perspectives of energy metabolism, oxidative stress, calcium homeostasis, and mitochondrial dynamics (including fission-fusion, transport, and mitophagy).

DNA nanotechnology-based nucleic acid delivery systems for bioimaging and disease treatment

Nucleic acids, including DNA and RNA, have been considered as powerful and functional biomaterials owing to their programmable structure, good biocompatibility, and ease of synthesis. However, traditional nucleic acid-based probes have always suffered from inherent limitations, including restricted cell internalization efficiency and structural instability. In recent years, DNA nanotechnology has shown great promise for the applications of bioimaging and drug delivery. The attractive superiorities of DNA nanostructures, such as precise geometries, spatial addressability, and improved biostability, have enabled them to be a novel category of nucleic acid delivery systems for biomedical applications. In this review, we introduce the development of DNA nanotechnology, and highlight recent advances of DNA nanostructure-based delivery systems for cellular imaging and therapeutic applications. Finally, we propose the challenges as well as opportunities for the future development of DNA nanotechnology in biomedical research.

Functional Nucleic Acid Probes Based on Two-Photon for Biosensing

Functional nucleic acid (FNA) probes have been widely used in environmental monitoring, food analysis, clinical diagnosis, and biological imaging because of their easy synthesis, functional modification, flexible design, and stable properties. However, most FNA probes are designed based on one-photon (OP) in the ultraviolet or visible regions, and the effectiveness of these OP-based FNA probes may be hindered by certain factors, such as their potential for photodamage and limited light tissue penetration. Two-photon (TP) is characterized by the nonlinear absorption of two relatively low-energy photons of near-infrared (NIR) light with the resulting emission of high-energy ultraviolet or visible light. TP-based FNA probes have excellent properties, including lower tissue self-absorption and autofluorescence, reduced photodamage and photobleaching, and higher spatial resolution, making them more advantageous than the conventional OP-based FNA probes in biomedical sensing. In this review, we summarize the recent advances of TP-excited and -activated FNA probes and detail their applications in biomolecular detection. In addition, we also share our views on the highlights and limitations of TP-based FNA probes. The ultimate goal is to provide design approaches for the development of high-performance TP-based FNA probes, thereby promoting their biological applications.

Three-Dimensional CHA-HCR System Using DNA Nanospheres for Sensitive and Rapid Imaging of miRNA in Live Cells and Tissues

Isothermal, enzyme-free amplification techniques, such as the hybridization chain reaction (HCR) and catalytic hairpin assembly (CHA), have gained increasing attention for miRNA analysis. However, current methodological challenges, including slow kinetics, low amplification efficiency, difficulties in efficient cellular internalization of DNA probes, and concerns regarding the intracellular stability of nucleic acids, need to be addressed. To this end, we propose a novel strategy for sensitive miRNA detection based on a three-dimensional (3D) CHA-HCR system. This system comprises two DNA nanospheres, named DS-13 and DS-24, which are functionalized with CHA and HCR hairpins. Target miR-21 initiates CHA between the two nanospheres, thereby activating downstream HCR and bringing cyanine 3 (Cy3) and cyanine 5 (Cy5) into proximity. The 3D CHA-HCR process leads to the formation of large DNA aggregates and the generation of fluorescence resonance energy transfer signals. In this strategy, the employment of a cascaded reaction and spatial confinement effect improve sensitivity and kinetics, while the use of DNA nanocarriers facilitates cellular delivery and protects nucleic acid probes. The experimental results in vitro, in living cells, and in clinical tissue samples demonstrated the desirable sensing performance. Collectively, this approach holds promise as a valuable tool for cancer diagnosis and biomedical research.

Modular Assembly of a Concatenated DNA Circuit for In Vivo Amplified Aptasensing

Probing endogenous molecular profiles in living entities is of fundamental significance to decipher biological functions and exploit novel theranostics. Despite programmable nucleic acid-based aptasensing systems across the breadth of molecular imaging, an aptasensing system enabling in vivo imaging with high sensitivity, accuracy, and adaptability is highly required yet is still in its infancy. Artificial catalytic DNA circuits that can modularly integrate to generate multiple outputs from a single input in an isothermal autonomous manner, have supplemented powerful toolkits for intracellular biosensing research. Herein, a multilayer nonenzymatic catalytic DNA circuits-based aptasensing system is devised for in situ imaging of a bioactive molecule in living mice by assembling branched DNA copolymers with high-molecular-weight and high-signal-gain based on avalanche-mimicking hybridization chain reactions (HCRs). The HCRs aptasensing circuit performs as a general and powerful sensing platform for precise analysis of a series of bioactive molecules due to its inherent rich recognition repertoire and hierarchical reaction accelerations. With tumor-targeting capsule encapsulation, the HCRs aptasensing circuit is specifically delivered into tumor cells and allowed the high-contrast imaging of intracellular adenosine triphosphate in living mice, highlighting its potential for visualizing these clinically important biomolecules and for studying the associated physiological processes.

Fluorescent Aptasensor for Highly Specific Detection of ATP Using a Newly Screened Aptamer

Owing to the significant roles of adenosine triphosphate (ATP) in diverse biological processes, ATP level is used to research and evaluate the physiological processes of organisms. Aptamer-based biosensors have been widely reported to achieve this purpose, which are superior in their flexible biosensing mechanism, with a high sensitivity and good biocompatibility; however, the aptamers currently used for ATP detection have a poor ability to discriminate ATP from adenosine diphosphate (ADP) and adenosine monophosphate (AMP). Herein, an ATP-specific aptamer was screened and applied to construct a fluorescent aptasensor for ATP by using graphene oxide (GO) and strand displacement amplification (SDA). The fluorescence intensity of the sensor is linearly related to the concentration of ATP within 0.1 μM to 25 μM under optimal experimental conditions, and the detection limit is 33.85 nM. The biosensor exhibits a satisfactory specificity for ATP. Moreover, the experimental results indicate that the biosensor can be applied to determine the ATP in human serum. In conclusion, the screened aptamer and the biosensor have promising applications in the determination of the real energy charge level and ATP content in a complex biological system.

Multivalent self-assembled nano string lights for tumor-targeted delivery and accelerated biomarker imaging in living cells and in vivo

Multivalent self-assembled nano string lights for tumor-targeted delivery with high efficiency and accelerated biomarker imaging in living cells and in vivo.