ATP-responsive mitochondrial probes for monitoring metabolic processes of glioma stem cells in a 3D model

Construction of a novel near-infrared fluorescent Nile blue@MOF nanoprobe for imaging mitochondrial ATP in living cells

A near-infrared fluorescent nanoprobe consisting of Nile blue-capped ZIF-90 is first proposed for real-time imaging of mitochondrial ATP. Owing to the strong binding of ATP with Zn2+, the structure of the probe is disrupted, leading to the release of fluorescent NB.

Three-Four Photon Transition Mn(II) Complex Monitoring Lysosome-Related ATP in Real Time via Fluorescence Lifetime Imaging

Currently, in situ monitoring of the adenosine triphosphate (ATP) level in lysosomes is critical to understand their involvement in various biological processes, but it remains difficult due to the interferences of limited targeting and low resolution of fluorescent probes. Herein, we report a classic Mn(II) probe (FX2-MnCl2) with near-infrared (NIR) nonlinear (NLO) properties, accompanied by three-four photon transition and fivefold fluorescence enhancement in the presence of ATP. FX2-MnCl2 combines with ATP through dual recognition sites of diethoxy and manganese ions to reflect slightly fluorescence lifetime change. Through the synergy of multiphoton fluorescence imaging (MP-FI) and multiphoton fluorescence lifetime imaging microscopy (MP-FLIM), it is further demonstrated that FX2-MnCl2 displays lysosome-specific targeting behavior, which can monitor lysosome-related ATP migration under NIR laser light. This work provides a novel multiphoton transformation fluorescence complex, which might be a potential candidate as a simple and straightforward biomarker of lysosome ATP in vitro for clinical diagnosis.

Tumor Therapy Strategies Based on Microenvironment-Specific Responsive Nanomaterials

The tumor microenvironment (TME) is a complex and variable region characterized by hypoxia, low pH, high redox status, overexpression of enzymes, and high-adenosine triphosphate concentrations. In recent years, with the continuous in-depth study of nanomaterials, more and more TME-specific response nanomaterials are used for tumor treatment. However, the complexity of the TME causes different types of responses with various strategies and mechanisms of action. Aiming to systematically demonstrate the recent advances in research on TME-responsive nanomaterials, this work summarizes the characteristics of TME and outlines the strategies of different TME responses. Representative reaction types are illustrated and their merits and demerits are analyzed. Finally, forward-looking views on TME-response strategies for nanomaterials are presented. It is envisaged that such emerging strategies for the treatment of cancer are expected to exhibit dramatic trans-clinical capabilities, demonstrating the extensive potential for the diagnosis and therapy of cancer.

Pollution-Free and Highly Sensitive Lactate Detection in Cell Culture Based on a Microfluidic Chip

Cell metabolite detection is important for cell analysis. As a cellular metabolite, lactate and its detection play an important role in disease diagnosis, drug screening and clinical therapeutics. This paper reports a microfluidic chip integrated with a backflow prevention channel for cell culture and lactate detection. It can effectively realize the upstream and downstream separation of the culture chamber and the detection zone, and prevent the pollution of cells caused by the potential backflow of reagent and buffer solutions. Due to such a separation, it is possible to analyze the lactate concentration in the flow process without contamination of cells. With the information of residence time distribution of the microchannel networks and the detected time signal in the detection chamber, it is possible to calculate the lactate concentration as a function of time using the de-convolution method. We have further demonstrated the suitability of this detection method by measuring lactate production in human umbilical vein endothelial cells (HUVEC). The microfluidic chip presented here shows good stability in metabolite quick detection and can work continuously for more than a few days. It sheds new insights into pollution-free and high-sensitivity cell metabolism detection, showing broad application prospects in cell analysis, drug screening and disease diagnosis.

Machine learning-empowered cis-diol metabolic fingerprinting enables precise diagnosis of primary liver cancer

Cis-diol metabolic reprogramming evolves during primary liver cancer (PLC) initiation and progression. However, owing to the low concentrations and highly structural heterogeneity of cis-diols in vivo, severe interference from complex biofluids and limited profiling coverage of existing methods, in-depth profiling of cis-diol metabolites and linking their specific changes with PLC remain challenging. Besides, due to the low specificity of widely used protein biomarkers, accurate classification of PLC from hepatitis still represents an unmet need in clinical diagnostics. Herein, to high-coverage profile cis-diols and explore the translational potential of them as biomarkers, a machine learning-empowered boronate affinity extraction-solvent evaporation assisted enrichment-mass spectrometry (MLE-BESE-MS) was developed. A single analytical platform integrated with multiple complementary functions, including pH-controlled boronate affinity extraction, solvent evaporation-assisted enrichment and nanoelectrospray ionization-based cis-diol identification, was constructed, which significantly improved the metabolite coverage. Meanwhile, by virtue of machine learning (principal components analysis, orthogonal partial least-squares discrimination analysis and random forest), collected cis-diols were statistically screened to extract efficient features for precise PLC diagnosis, and the results outperform the routinely used protein biomarker-based methods both in sensitivity (87.5% vs. less than 70%) and specificity (85.7% vs. ca. 80%). This machine learning-empowered integrated MS platform advanced the targeted metabolic analysis for early cancer diagnosis, rendering great promise for clinical translation.

Microfluidic biosensor for one-step detection of multiplex foodborne bacteria ssDNA simultaneously by smartphone

As a major threat to food safety due to their pathogenicity, foodborne bacteria have received much attention. In this paper, we present a one-step and wash-free microfluidic biosensor platform by smartphone for simultaneous multiple foodborne bacteria target single-stranded DNA (ssDNA) detection. This technology is based on the fluorescence resonance energy transfer (FRET) between the graphene oxide (GO) and fluorescence molecules modified capture ssDNA of the target bacteria ssDNA (ctDNA) which were coated on the microfluidic chips. The fluorescence recovery was recorded by a smartphone fluorescent detector. With an optimal analytical performance, the platform realized the detection of four kinds of bacteria ssDNA simultaneously within 5 min, with the limits of detection (LODs) of 0.17, 0.18, 0.27, and 0.17 nM, respectively. And the throughput analysis of trace amounts of foodborne bacteria ssDNA in milk and water samples were successfully detected. This one-step and wash-free microfluidic biosensor can be used as a tool for food safety analysis.

A genetically encoded fluorescent biosensor for monitoring ATP in living cells with heterobifunctional aptamers

Visualizing the dynamics of ATP in living cells is key to understanding cellular energy metabolism and related diseases. However, the live-cell applications of current methods are still limited due to challenges in biological compatibility and sensitivity to pH. Herein, a novel label-free fluorescent " turn-on " biosensor for monitoring ATP in living bacterias and mammalian cells was developed. This biosensor (Broc-ATP) employed heterobifunctional aptamers to detect ATP with high sensitivity in vitro. In our system, a very useful tandem method was established by combining four Broc-ATPs with 3 × F30 three-way junction scaffold to construct an intracellular biosensor that achieves sufficient fluorescence to respond to intracellular ATP. This intracellular biosensor can be used for sensitive and specific dynamic imaging of ATP in mammalian cells. Hence, this genetically encoded biosensor provides a robust and efficient tool for the detection of intracellular ATP dynamics and 3 × F30 tandem method expands the application of heterobifunctional aptamers in mammalian cells.

Development of the DNA-based biosensors for high performance in detection of molecular biomarkers: More rapid, sensitive, and universal

The molecular biomarkers are molecules that are closely related to specific physiological states. Numerous molecular biomarkers have been identified as targets for disease diagnosis and biological research. To date, developing highly efficient probes for the precise detection of biomarkers has become an attractive research field which is very important for biological and biochemical studies. During the past decades, not only the small chemical probe molecules but also the biomacromolecules such as enzymes, antibodies, and nucleic acids have been introduced to construct of biosensor platform to achieve the detection of biomarkers in a highly specific and highly efficient way. Nevertheless, improving the performance of the biosensors, especially in clinical applications, is still in urgent demand in this field. A noteworthy example is the Corona Virus Disease 2019 (COVID-19) that breaks out globally in a short time in 2020. The COVID-19 was caused by the virus called SARS-CoV-2. Early diagnosis is very important to block the infection of the virus. Therefore, during these months scientists have developed dozens of methods to achieve rapid and sensitive detection of the virus. Nowadays some of these new methods have been applied for producing the commercial detection kit and help people against the disease worldwide. DNA-based biosensors are useful tools that have been widely applied in the detection of molecular biomarkers. The good stability, high specificity, and excellent biocompatibility make the DNA-based biosensors versatile in application both in vitro and in vivo. In this paper, we will review the major methods that emerged in recent years on the design of DNA-based biosensors and their applications. Moreover, we will also briefly discuss the possible future direction of DNA-based biosensors design. We believe this is helpful for people interested in not only the biosensor field but also in the field of analytical chemistry, DNA nanotechnology, biology, and disease diagnosis.

3D microfluidic tumor models for biomimetic engineering of glioma niche and detection of cell morphology, migration and phenotype change

In this work, an integrated 3-dimensional microfluidic device was developed for simulation of the immune microenvironment of glioma niche through the co-culture of three kinds of related cells. Glioma cells, endothelial cells and macrophages were co-cultured together in the microfluidic device, spatially separated by the design of a coffer structure and the use of hydrogel. This platform enabled separate monitoring of the morphology change and migration of cells, as well as molecular interactions between different kinds of cells. Tumor cells were found to exhibit EMT like shape change to become thinner, and sensitive perception and taxis toward macrophages. The influence of tumor cells and the microenvironment, macrophages would be re-educated and the phenotype could be changed from M1 (tumor-suppressive) to M2 (tumor-supportive), which could be validated through cytokines analysis. This 3D microfluidic tumor model provides a powerful tool for studying the biological properties of glioma niche.