In this study, the reductive amination method was used to label IR783 on Astragalus polysaccharides(APS) for the first time, which was verified by ultraviolet-visible spectroscopy and infrared spectroscopy. Quantitative analysis methods of APS-IR783 in plasma and various tissue were established using a multifunctional microplate reader. The pharmacokinetics and tissue distribution of APS-IR783 in mice were investigated after a single intravenous injection of 30 mg·kg~(-1) APS-IR783, and pharmacokinetic parameters were calculated using DAS 2.0 software. The results showed that the APS used had a mass fraction of 93.69%, a relative molecular weight of 1.55×10~5, and a polydispersity index(PDI, M_w/M_n) of 1.73, close to a homogeneous polysaccharide. The IR783 labeling yield reached 86.50%, and the content of IR783 in APS-IR783 was 0.72%. After a single intravenous injection of 30 mg·kg~(-1), the pharmacokinetic parameters of APS in mouse plasma were as follows: T_(max) was(0.67±0.26) h; C_(max) was(1 599.29±159.30) mg·L~(-1); T_(1/2α) and T_(1/2β) were(2.29±3.06) h and(0.44±0.05) h, respectively; AUC_(0-t) was(23 398.91±2 907.03) mg·h·L~(-1); AUC_(0-∞) was(27 710.55±3 506.55) mg·h·L~(-1); MRT_(0-∞) was(34.38±12.59) h; CL was 0.001 L·h~(-1)·kg~(-1); V_z was(0.042±0.017) L·kg~(-1). The in vivo biodistribution study demonstrated that the in vivo exposure ratios of APS in different tissue were in the following order: spleen > liver > kidney > lung > heart > small intestine > muscle > large intestine > brain > stomach, where the top five tissue accounted for 87.54% of the total area under the curve(AUC). This study successfully labeled APS with a water-soluble near-infrared fluorescent probe of IR783 for the first time and revealed the pharmacokinetics and tissue distribution of APS in mice. The paper provides detailed in vivo behavior of APS after intravenous injection, which lays the foundation for the development and utilization of APS and related natural medicines.
Animals ; Mice ; Polysaccharides/chemistry* ; Tissue Distribution ; Astragalus Plant/chemistry* ; Male ; Drugs, Chinese Herbal/chemistry* ; Fluorescent Dyes/pharmacokinetics* ; Female

Transaminases are a class of enzymes that catalyze the transfer of amino between amino acids and keto acids, playing an important role in the biosynthesis of organic amines and the corresponding derivatives. However, natural enzymes often have low catalytic efficiency against non-natural substrates, which limits their widespread applications. Enzyme engineering serves as an effective approach to improve the catalytic properties and thereby expand the application scope of transaminases. In this study, a high-throughput screening method for transaminases was established based on the fluorescent color reaction between methoxy-2-aminobenzoxime (PMA) and ketones. According to the changes in fluorescence intensity, the concentration changes of ketones could be easily monitored. The efficiency, sensitivity, and accuracy of the screening method were improved by optimization of the system. With 4-hydroxy-2-butanone as the substrate, the mutant library of the transaminase from Actinobacteria sp. was established and a mutant with increased activity was successfully obtained, which improved the production efficiency of (R)-3-aminobutanol by enzyme-catalyzed synthesis. This study laid an important foundation for efficient screening, modification, and application of transaminase.
Transaminases/metabolism* ; Fluorescent Dyes/chemistry* ; High-Throughput Screening Assays/methods* ; Ketones/metabolism* ; Actinobacteria/enzymology*

OBJECTIVE: To investigate the imaging effect of a near-infrared fluorescent targeted probe ICG-NP41 on the neurovascular bundles (NVB) around the prostate in rats. METHODS: A near-infrared fluorescent targeted probe ICG-NP41 was synthesized. An animal model for NVB imaging was established using Sprague-Dawley rats (250-400 g). Experiments were conducted using a custom-built near-infrared windowⅡ(NIR-Ⅱ) small animal in vivo imaging system, and images collected were processed using ImageJ and Origin. The fluorescence signal data were statistically analyzed using GraphPad Prism. The signal-to-background ratio (SBR) for NVB was quantitatively calculated to explore the effective dosage and imaging time points. Finally, paraffin pathology sections and HE staining were performed on the imaging structures. RESULTS: Except for rats in the control group (n=2), right-sided NVB of the rats injected with ICG-NP41 (n=2 per group) were all observed in NIR-Ⅱ fluorescence mode 2 h and 4 h after administration. At 2 h and 4 h, average SBR of cavernous nerve in 2 mg/kg group in fluorescence mode was 1.651±0.142 and 1.619±0.110, respectively, both higher than that in white light mode (1.111±0.036), with no significant difference (P>0.05); average SBR of 4 mg/kg group in fluorescence mode were 1.168±0.066 and 1.219±0.118, respectively, both higher than that in white light mode (1.081±0.040), with no significant difference (P>0.05). At 2 h and 4 h, the average SBR of 2 mg/kg and 4 mg/kg groups in fluorescence mode were higher than that of the control group (SBR=1), the average SBR of the 2 mg/kg group was higher than that of the 4 mg/kg group, and all the above with no significant difference (P>0.05). The average diameter of the nerve measured by full width at half maxima method was about (178±15) μm. HE staining of paraffin sections showed the right major pelvic ganglion. CONCLUSION The near-infrared fluorescent targeted probe ICG-NP41 can be used for real-time imaging of the NVB around the prostate in rats, providing a potential feasible solution for localizing NVB in real time during nerve-sparing radical prostatectomy.
Male ; Rats ; Animals ; Prostate/diagnostic imaging* ; Paraffin ; Indocyanine Green ; Rats, Sprague-Dawley ; Fluorescent Dyes

Flow cytometry is a multi-parameter, rapid and efficient method for qualitative analysis and quantitative determination of various fluorescently labeled particles in liquid flow. Flow cytometry has been applied in multiple disciplines such as immunology, virology, molecular biology, cancer biology and infectious disease monitoring. However, the application of flow cytometry in plant research is hampered due to the special composition and structure of plant tissues and cells, such as cell walls and secondary metabolites. In this paper, the development, composition and classification of flow cytometry were introduced. Subsequently, the application, research progress and application limitations of flow cytometry in plant field were discussed. At last, the development trend of flow cytometry in plant research was prospected, which provides new perspectives for broadening the potential application scope of plant flow cytometry.
Flow Cytometry/methods* ; Plants ; Fluorescent Dyes

This paper reviews the research progress on live-cell super-resolution fluorescence microscopy, discusses the current research status and hotspots in this field, and summarizes the technological application of super-resolution fluorescence microscopy for live-cell imaging. To date, this field has gained progress in numerous aspects. Specifically, the structured illumination microscopy, stimulated emission depletion microscopy, and the recently introduced minimal photon fluxes microscopy are the current research hotspots. According to the current progress in this field, future development trend is likely to be largely driven by artificial intelligence as well as advances in fluorescent probes and relevant labelling methods.
Artificial Intelligence ; Microscopy, Fluorescence ; Fluorescent Dyes ; Technology

INTRODUCTION: Oropharyngeal swabs for diagnosis of COVID-19 often induce violent coughing, which can disperse infectious droplets onto providers. Incorrectly doffing personal protective equipment (PPE) increases the risk of transmission. A cheap, single-use variation of the face shield invented by a Singaporean team, SG Shield, aims to reduce this risk. This manikin study aimed to study the efficacy of the SG Shield in combination with standard PPE. METHODS: A person attired in full PPE whose face and chest was lined with grid paper stood in front of an airway manikin in an enclosed room. A small latex balloon containing ultraviolet fluorescent dye was placed in the oral cavity of the manikin and inflated until explosion to simulate a cough. Three study groups were tested: (a) control (no shield), (b) face shield and (c) SG Shield. The primary outcome was droplet dispersion, determined quantitatively by calculating the proportion of grid paper wall squares stained with fluorescent dye. The secondary outcome was the severity of provider contamination. RESULTS: The SG Shield significantly reduced droplet dispersion to 0% compared to the controls (99.0%, P = 0.001). The face shield also significantly reduced droplet contamination but to a lesser extent (80.0%) compared to the control group (P = 0.001). Although the qualitative severity of droplet contamination was significantly lower in both groups compared to the controls, the face shield group had more contamination of the provider's head and neck. CONCLUSION The manikin study showed that the SG Shield significantly reduces droplet dispersion to the swab provider's face and chest.
Humans ; Infectious Disease Transmission, Patient-to-Professional/prevention & control* ; COVID-19 ; Fluorescent Dyes ; Personal Protective Equipment ; Cough

The current quantitative methods of bilirubin have disadvantages such as high cost and low sensitivity. Due to the negative correlation between the level of serum bilirubin and the risk of cardiovascular diseases, a fluorescent ratiometric film sensor was developed aiming at bilirubin detection at low level concentration. Blue-emitting and red-emitting gold nanoclusters were assembled into the same film using layer-by-layer self-assembly technology. Detection of bilirubin was achieved based on the intensity ratio of the two nanoclusters. Bilirubin exposure causes fluorescent quenching of the film. The fluorescence intensity ratio of the two cluster probes had quantitative relationship versus bilirubin concentration. Based on this film sensor, a portable fluorescence detection system was designed for the ratiometric sensing of bilirubin. The hardware of the system was mainly composed of main control chip STM32F407, TSL237 and TSL238T optical frequency sensor. A light-avoiding dark room and detection light path were designed through three-dimensional printing to reduce the interference from ambient light and improve detection accuracy. Experimental results showed that the proposed detection system had strong anti-interference, good stability and accuracy. The linear coefficient of bilirubin detected by this system was 0.987. The system presented good results in reproducible experiments and possessed a good linear relationship with the data obtained by standard spectrofluorometer. The portable system is expected to detect serum bilirubin at low levels.
Bilirubin ; Fluorescence ; Fluorescent Dyes ; Gold ; Metal Nanoparticles ; Spectrometry, Fluorescence/methods*

The aim of this study was to construct a simple, rapid and ultra-sensitive optical biosensing technique based on rolling circle amplification (RCA), and to apply it to multiple detection of drug-resistant genes of mycobacterium tuberculosis. The common mutation sites of isoniazid, rifampicin and streptomycin resistance genes are katG315 (AGC➝ACC), rpoB531 (CAC➝TAC) and rpsL43 (AAG➝AGG). For these three gene sites, from February 2020 to May 2021, in the Department of Laboratory Medicine of the First Affiliated Hospital of Army Military Medical University, the padlock probe (PLP), primers and capture probes were designed. And a solid-phase RCA constant temperature amplification reaction system based on magnetic beads was constructed and the experimental parameters were optimized. The RCA products were accurately captured by the multicolor fluorescent probes (Cy3/Cy5/ROX), and the single-tube multiple detection of three mutation genes was realized. The sensitivity, specificity and linear range of this method were further verified. The results showed that the response range of katG315 in the same reaction system ranged from 1.0 pmol/L to 0.1 nmol/L. The response range of rpoB531 and rpsL43 ranged from 1.0 pmol/L to 50.0 pmol/L and 1.0 pmol/L to 20.0 pmol/L, and the method had good specificity and sensitivity, and could accurately identify single base mutations in mixed targets, with the minimum detection limit as low as 1.0 pmol/L. The recoveries of simulated serum samples were 95.0%-105.2%. In conclusion, the constant temperature amplification multiple detection method constructed in this study can quickly realize the single-tube multiple detection of three drug resistance mutation sites. This technology is low-cost, simple and rapid, and does not rely on large equipment, providing a new analysis method for pathogen drug resistance gene detection.
Drug Resistance ; Fluorescent Dyes ; Humans ; Mycobacterium tuberculosis/genetics* ; Nucleic Acid Amplification Techniques

OBJECTIVE: To investigate the inhibitory effect of RSL3 on the proliferation, invasion and migration of cisplatinresistant testicular cancer cells (I-10/DDP) and the effect of carbenoxolone on the activity of RSL3 against testicular cancer. METHODS: MTT assay was used to evaluate the survival rate of I-10/DDP cells following treatment with RSL3 (1, 2, 4, 8, 16 or 32 μmol/L) alone or in combination with carbenoxolone (100 μmol/L) or after treatment with Fer-1 (2 μmol/L), RSL3 (4 μmol/L), RSL3+Fer-1, RSL3+carbenoxolone (100 μmol/L), or RSL3+Fer-1+carbenoxolone. Colony formation assay was used to assess the proliferation ability of the treated cells; wounding-healing assay and Transwell assay were used to assess the invasion and migration ability of the cells. The expression of GPX4 was detected using Western blotting, the levels of lipid ROS were detected using C11 BODIPY 581/591 fluorescent probe, and the levels of Fe²⁺ were determined with FerroOrange fluorescent probe. RESULTS: RSL3 dose-dependently decreased the survival rate of I-10/DDP cells, and the combined treatment with 2, 4, or 8 μmol/L RSL3 with carbenoxolone, as compared with RSL3 treatment alone, resulted in significant reduction of the cell survival rate. The combination with carbenoxolone significantly enhanced the inhibitory effect of RSL3 on colony formation, wound healing rate (P=0.005), invasion and migration of the cells (P < 0.001). Fer-1 obviously attenuated the inhibitory effects of RSL3 alone and its combination with carbenoxolone on I-10/DDP cells (P < 0.01). RSL3 treatment significantly decreased GPX4 expression (P=0.001) and increased lipid ROS level (P=0.001) and Fe²⁺ level in the cells, and these effects were further enhanced by the combined treatment with carbenoxolone (P < 0.01). CONCLUSION Carbenoxolone enhances the inhibitory effect of RSL3 on the proliferation, invasion and migration of cisplatin-resistant testicular cancer cells by promoting RSL3-induced ferroptosis.
Carbenoxolone/pharmacology* ; Cell Line, Tumor ; Cell Proliferation ; Cisplatin/pharmacology* ; Ferroptosis ; Fluorescent Dyes/pharmacology* ; Humans ; Lipids ; Male ; Neoplasms, Germ Cell and Embryonal ; Reactive Oxygen Species ; Testicular Neoplasms

OBJECTIVE: To explore the mechanism by which berberine inhibits ferroptosis of mouse hippocampal neuronal cells (HT22). METHODS: Cultured HT22 cells were pretreated with 30 or 60 μmol/L berberine for 2 h before exposure to 0.5 μmol/L erastin for 8 h, and the cell proliferation, intracellular ferric iron level, changes in intracellular reactive oxygen species (ROS) and cell apoptosis were detected using CCK-8, Fe²⁺ fluorescent probe, fluorescent dye (DAPI) and fluorescent probe (H2DCFH-DA). RT-qPCR and Western blotting were used to detect the mRNA and protein expressions of Nrf2, HO-1 and GPX4 in the cells. We further tested the effects of treatments with 2 μmol/L ML385 (a Nrf2 inhibitor), 60 μmol/L berberine and erastin in the cells to explore the protective mechanism of berberine against erastin-induced ferroptosis in the neuronal cells. RESULTS: Treatment with 0.5 μmol/L erastin significantly lowered the viability of HT22 cells (P < 0.05) and increased the production of ROS, cell apoptosis rate and ferric iron level (P < 0.05). Pretreatment with 30 and 60 μmol/L berberine both significantly increased the vitality of erastin-exposed cells (P < 0.05) and lowered the levels of intracellular ROS and ferric iron content (P < 0.05). RT-qPCR and Western blotting showed that berberine obviously promoted the expressions of Nrf2, HO-1 and GPX4 in the cells (P < 0.05), and treatment with ML385 significantly inhibited the Nrf2-HO-1/GPX4 pathway, increased intracellular ROS and ferric iron contents and mitigated the protective effect of berberine against erastin-induced ferroptosis (P < 0.05). CONCLUSION Berberine can inhibit erastin-induced ferroptosis in HT22 cells possibly by activating the Nrf2-HO-1/ GPX4 pathway.
Animals ; Berberine/pharmacology* ; Ferroptosis ; Fluorescent Dyes ; Hippocampus/metabolism* ; Iron/metabolism* ; Mice ; NF-E2-Related Factor 2/metabolism* ; Piperazines ; Reactive Oxygen Species/metabolism*