Lighting up endogenous H2O2 in the tumor microenvironment using a dual-mode nanoprobe for long afterglow and MR bioimaging.

Persistent luminescent nanoparticles (PLNPs) are excellent luminescent materials, and near-infrared PLNPs are efficiently applied for biosensing and bioimaging due to their advantages of no excitation, excellent light stability and long afterglow. However, due to interference from the complex environment within organisms, single-mode imaging methods often face limitations in selectivity, sensitivity, and accuracy. Therefore, it is desirable to construct a dual-mode imaging probe strategy with higher specificity and sensitivity for bioimaging. Magnetic resonance imaging (MRI) has been widely used in the field of bioimaging due to its advantages of high resolution, non-radiation and non-invasiveness. Here, by combining near-infrared PLNPs and manganese dioxide (MnO2) nanosheets, a sensitive and convenient dual-mode "turn on" bioimaging nanoprobe ZGC@MnO2 has been developed for long afterglow imaging and MRI of endogenous hydrogen peroxide (H2O2) in the tumor microenvironment (TME). The monitoring of H2O2 has garnered significant attention due to its crucial role in human pathologies. For the dual-mode "turn on" bioimaging nanoprobe, the near-infrared PLNPs of quasi-spherical ZnGa2O4:Cr (ZGC) nanoparticles were synthesized as luminophores, and MnO2 nanosheets were utilized as a fluorescence quencher, carrier and H2O2 recognizer. H2O2 in the TME could reduce MnO2 nanosheets to Mn2+ for MRI, and ZGC nanoparticles were released for long afterglow imaging. Finally, the ZGC@MnO2 nanoprobe exhibited a rapid response, an excellent signal-to-noise ratio and a limit of detection of 3.67 nM for endogenous H2O2 in the TME. This dual-mode approach enhances the detection sensitivity for endogenous H2O2, thereby facilitating the research of endogenous H2O2-associated diseases and clinical diagnostics.

A DNA octahedral amplifier for endogenous circRNA detection and bioimaging in living cells and its biomarker study.

The discovery of reliable biomarkers is essential for early diagnosis, treatment, and prognosis assessment of diseases. Many research studies have shown that circRNA is a potential biomarker for diagnosis and prognosis of diseases. However, in situ monitoring circRNA in live cells is still a challenge at present, which brings a major limitation to the development and verification of circRNA as a disease biomarker. In this study, a catalytic hairpin assembly (CHA) reaction-based DNA octahedral amplifier (DOA) was developed for fluorescence resonance energy transfer (FRET) detection and bioimaging of circRNA in living cells. The DOA was first produced by self-assembling a DNA octahedron with six customized single-stranded DNAs, and two hairpins H1 (Cy3) and H2 (Cy5) were then hybridized to four vertices of the DNA octahedron. Idiopathic pulmonary fibrosis (IPF)-related circHIPK3 was used as the target. Once the CHA reaction from H1 and H2 on DOA was activated by a sequence-specific back-splice junction (BSJ) of circHIPK3, a significant FRET signal can be obtained from Cy3 to Cy5. The circHIPK3 was subsequently released to cause the next CHA reaction. Because the DOA has the advantages of the spatial-confinement effect, resistance to nuclease degradation and easy penetration into cells, rapid and excellent signal amplification FRET detection and bioimaging of endogenous circHIPK3 can be achieved in various cells. This study provides a high-precision assay platform to explore the possibility of using circRNA as a biomarker, and it is valuable for circRNA-related early diagnosis and treatment of diseases.

Quantifying the ecological carrying capacity of grasslands in Inner Mongolia.

Quantifying the ecological carrying capacity has emerged as a crucial factor for maintaining ecosystem stability for sustainable development in vulnerable eco-regions. Here, we propose a new framework for ecological carrying capacity quantification suitable for vulnerable eco-regions. We applied this framework to calculate the ecological carrying capacity of Inner Mongolia from 1987-2015 and used a geographical detector to identify the driving factors behind spatial heterogeneity. Our results revealed the following. (1) The above-ground net primary production (ANPP) required to support the ecosystem service of soil conservation (ANPPSC) decreased from northeast to southwest, whereas the distribution pattern of ANPP required to support the ecosystem service of sand fixation (ANPPSF) exhibited a contrary trend. The average annual ANPP required to support the ecosystem service of natural regeneration (ANPPNR) in Inner Mongolia from 1987 to 2015 was 101.27 gCm-2year-1, revealing a similar spatial distribution with ANPP. (2) The total ecological carrying capacity of Inner Mongolian grassland was 78.52 million sheep unit hm-2. The regions with insufficient provisioning service capability accounted for 4.18% of the total area, primarily concentrated in the east and northwest. (3) The average optimal livestock number for grasslands in Inner Mongolia was 1.59 sheep unit hm-2 from 1987-2015, ranging from 0.77 to 1.69 sheep unit hm-2 across different zones. The average ecological carrying capacity of the cold temperate humid, medium-temperate arid, and warm temperate semi-humid regions was less than 1.08 sheep unit m-2, suggesting a need to prohibit grazing in these areas. (4) The primary influencing factors affecting ecological carrying capacity distribution were normalized difference vegetation index (NDVI), precipitation, and soil type. The framework developed herein can help identify sustainable development potential from the ecosystem service perspective and effectively contribute to decision-making in grassland ecosystem management.