A highly selective and sensitive method for Cd(II) detection was developed based on aptamer and gold nanoparticles (AuNPs) combined with a colorimetric smartphone readout. The experimental conditions such as reaction time of polydiene dimethyl ammonium chloride (PDDA) and AuNPs, PDDA dose, time of aptamer and PDDA incubation, and aptamer concentration were optimized. Under the optimized conditions, the color and red(R) value of the solution was concentration-dependent on Cd(II). The proposed method exhibited a linear range of 1–400 ng/mL (r² = 0.9794) with a limit of detection (LOD) of 1 ng/mL. This method had been successfully applied to test and quantify Cd(II) in water and rice samples, and the results were in full agreement with those from the atomic absorption spectrometer. Therefore, low-cost colorimetry demonstrated its potential for practical application in visual or quantitative detection with a smartphone. This approach can be readily applied to other analytes.

Glioblastoma (GBM) exhibits profound metabolic plasticity for survival and therapeutic resistance, while the underlying mechanisms remain unclear. Here, we show that GBM stem cells reprogram the epigenetic landscape by producing substantial amounts of phosphocreatine (PCr). This production is attributed to the elevated transcription of brain-type creatine kinase, mediated by Zinc finger E-box binding homeobox 1. PCr inhibits the poly-ubiquitination of the chromatin regulator bromodomain containing protein 2 (BRD2) by outcompeting the E3 ubiquitin ligase SPOP for BRD2 binding. Pharmacological disruption of PCr biosynthesis by cyclocreatine (cCr) leads to BRD2 degradation and a decrease in its targets’ transcription, which inhibits chromosome segregation and cell proliferation. Notably, cyclocreatine treatment significantly impedes tumor growth and sensitizes tumors to a BRD2 inhibitor in mouse GBM models without detectable side effects. These findings highlight that high production of PCr is a druggable metabolic feature of GBM and a promising therapeutic target for GBM treatment. Significance: Glioblastoma (GBM) exhibits an adaptable metabolism crucial for survival and therapy resistance. We demonstrate that GBM stem cells modify their epigenetics by producing phosphocreatine (PCr), which prevents bromodomain containing protein 2 (BRD2) degradation and promotes accurate chromosome segregation. Disrupting PCr biosynthesis impedes tumor growth and improves the efficacy of BRD2 inhibitors in mouse GBM models.

A novel ratiometric fluorescence probe based on nitrogen-doped blue carbon dots (NCDs) and red gold nanoclusters (Au NCs) for mercuric ion (Hg2+) has been prepared and characterized. A user friendly fluorescent test paper based sensor combined with smartphone was fabricated for rapid visual and quantitative detection. Hg²⁺ can specifically bind to Au⁺ on the surface of Au NCs, leading to the quench of red fluorescence while the fluorescence intensity of the NCDs with blue fluorescence remained unchanged as a internal standard signal. The implement of paper-based sensor address some common drawback in analytical process such as the detection time, analysis cost. In a further demonstration, a homemade detection device with smartphone was used to qualify the Hg²⁺. After adding different concentration of Hg²⁺, red, purple, and blue colors were obtained on the detection zones of the fluorescent test paper. The Android App Color Grab was used to identify the red, green and blue (RGB) values of fluorescent color. The rapid visual and quantitative detection of Hg²⁺ was accomplished with the detection limit of 2.7 nM for fluorescence, 25 nM for smartphone and 32 nM for paper strip. The developed multi-mode detection platform was successfully applied to the detection of mercury ions in water samples with acceptable recoveries. The NCDs and Au NCs probe facilitate the one-site environmental monitoring for Hg²⁺ with “naked-eye” and smartphone.

Microplastics are widespread environmental pollutants that can easily enter the bodies of living organisms through various means, arousing extensive concern. However, research regarding the influence of polyethylene terephthalate microplastics (PET-MPs) on the mammalian reproductive system is limited. This study explored the mechanisms by which PET-MPs induce reproductive toxicity in male mice. The results showed that after 90 days of continuous gavage exposure, PET-MPs with sizes of 50, 200, and 1000 nm accumulated in the testicular tissue. The results of the experiment showed the sperm quality and related hormone levels of mice declined. Hematoxylin and eosin (H&E) staining showed that spermatogenic cells were shed, disordered in arrangement, and vacuolated. Immunohistochemical results showed that spermatogenic cell proliferation was inhibited, and apoptosis was significantly increased. Transcriptome sequencing showed that PET-MP exposure activated the MAPK pathway in testicular tissues. Through the detection of key genes, proteins, and inflammatory factor levels in this pathway, we demonstrated that PET-MP exposure elevated inflammatory factor levels. These results provide a theoretical foundation for elucidating the impact of PET-MP exposure on the mammalian reproductive system.

Ochratoxin A (OTA) is a mycotoxin widely found in foodstuffs such as cereal grains. It greatly threatens human health owing to its strong toxicity and high stability. Aptasensors have emerged as promising tools for the analysis of small molecule contaminants. Nucleic-acid-based signal amplification enables detectable signals to be obtained from aptasensors. However, this strategy often requires the use of complex primers or multiple enzymes, entailing problems such as complex system instability. Herein, we propose a fluorescent aptasensor for the ultrasensitive detection of OTA in cereal products, with signal amplification through RecJ_f exonuclease-assisted target recycling. The aptamer/fluorescein-labeled complementary DNA (cDNA-FAM) duplex was effectively used as the target-recognition unit as well as the potential substrate for RecJ_f exonuclease cleavage. When the target invaded the aptamer-cDNA-FAM duplex to release cDNA-FAM, RecJ_f exonuclease could cleave the aptamer bonded with the target and release the target. Thus, the target-triggered cleavage cycling would continuously generate cDNA-FAM as a signaling group, specifically amplifying the response signal. The proposed exonuclease-assisted fluorescent aptasensor exhibited a good linear relationship with OTA concentration in the range from 1 pg/mL to 10 ng/mL with an ultralow limit of detection (6.2 ng/kg of cereal). The analytical method showed that recoveries of the cereal samples ranged from 83.7 to 109.3% with a repeatability relative standard deviation below 8%. Importantly, the proposed strategy is expected to become a common detection model because it can be adapted for other targets by replacing the aptamer. Thus, this model can guide the development of facile approaches for point-of-care testing applications.

Nanomaterials are desirable for sensing applications. Therefore, MnO₂ nanosheets and nitrogen-doped carbon dots (NCDs) were used to construct a ratiometric biosensor for quantification of 2,4-dichlorophenoxyacetic acid. The MnO₂ nanosheets drove the oxidation of colorless o-phenylenediamine to OPDox, which exhibits fluorescence emission peaks at 556 nm. The fluorescence of OPDox was efficiently quenched and the NCDs were recovered as the ascorbic acid produced by the hydrolyzed alkaline phosphatase (ALP) substrate increased. Owing to the selective inhibition of ALP activity by 2,4-D and the inner filter effect, the fluorescence intensity of the NCDs at 430 nm was suppressed, whereas that at 556 nm was maintained. The fluorescence intensity ratio was used for quantitative detection. The linear equation was F = 0.138 + 3.863·C 2,4-D (correlation coefficient R² = 0.9904), whereas the limits of detection (LOD) and quantification (LOQ) were 0.013 and 0.040 μg/mL. The method was successfully employed for the determination of 2,4-D in different vegetables with recoveries of 79%~105%. The fluorescent color change in the 2,4-D sensing system can also be captured by a smartphone to achieve colorimetric detection by homemade portable test kit.