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*

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

Indocyanine green (ICG) is the most commonly used near-infrared fluorescent (NIRF) dye in clinical practice, and its mediated near-infrared fluorescence imaging technology is gradually applied in clinical practice. It has shown great potential in invasive surgery (MIS) and is expected to become the standard technology for surgical diagnosis and treatment of diseases. The clinical application of ICG fluorescence laparoscopy is reviewed here.
Indocyanine Green ; Fluorescence ; Laparoscopy ; Coloring Agents

OBJECTIVE: To construct polyhydroxyalkanoate (PHA) microspheres loaded with bone morphogenetic protein 2 (BMP-2) and human β-defensin 3 (HBD3), and evaluate the antibacterial activity of microspheres and the effect of promoting osteogenic differentiation, aiming to provide a new option of material for bone tissue engineering. METHODS: The soybean lecithin (SL)-BMP-2 and SL-HBD3 were prepared by SL-mediated introduction of growth factors into polyesters technology, and the functional microsphere (f-PMS) containing BMP-2 and HBD3 were prepared by microfluidic technology, while pure microsphere (p-PMS) was prepared by the same method as the control. The morphology of microspheres was observed by scanning electron microscopy and the water absorption was detected; the release curves of BMP-2 and HBD3 in f-PMS were detected by ELISA kit. The antibacterial effect of microspheres in Staphylococcus aureus and Escherichia coli was tested with the LIVE/DEAD^TM BacLight^TM bacterial staining kit; the biocompatibility of microspheres was tested using Transwell and cell counting kit 8 (CCK-8). The effect of microspheres on osteogenic differentiation was determined by collagen type Ⅰ (COL-1) immunofluorescence staining and alkaline phosphatase (ALP) concentration. RESULTS: In this experiment, the f-PMS and p-PMS were successfully constructed. Morphological characteristics showed that p-PMS surface was rough and distributed with micropores of 1-3 μm, while f-PMS surface was smooth and existed white granular material. There was no significant difference in water absorption between the two groups (P>0.05). The release curves of BMP-2 and HBD3 in the f-PMS and p-PMS were basically the same, showing both early sudden release and late slow release. The antibacterial activity of f-PMS was significantly higher than that of p-PMS in the test that against Staphylococcus aureus and Escherichia coli (P<0.05), but there was no significant difference in biocompatibility between the two groups (P>0.05). The results of osteogenic differentiation of human BMSCs showed that the fluorescence intensity of osteogenic specific protein COL-1 of f-PMS was significantly higher than that in p-PMS, and the activity of ALP in f-PMS was also significantly higher than that in p-PMS (P<0.05). CONCLUSION The p-PHA have good antibacterial activity and biocompatibility, and can effectively promote the osteogenic differentiation of human BMSCs, which is expected to be applied to bone tissue engineering in the future.
Humans ; Osteogenesis ; Polyhydroxyalkanoates ; Microspheres ; Alkaline Phosphatase ; Anti-Bacterial Agents/pharmacology* ; Coloring Agents ; Escherichia coli

OBJECTIVE: To design and construct a graphene oxide (GO)/silver nitrate (Ag₃PO₄)/chitosan (CS) composite coating for rapidly killing bacteria and preventing postoperative infection in implant surgery. METHODS: GO/Ag₃PO₄ composites were prepared by ion exchange method, and CS and GO/Ag₃PO₄ composites were deposited on medical titanium (Ti) sheets successively. The morphology, physical image, photothermal and photocatalytic ability, antibacterial ability, and adhesion to the matrix of the materials were characterized. RESULTS: The GO/Ag₃PO₄ composites were successfully prepared by ion exchange method and the heterogeneous structure of GO/Ag₃PO₄ was proved by morphology phase test. The heterogeneous structure formed by Ag₃PO₄ and GO reduced the band gap from 1.79 eV to 1.39 eV which could be excited by 808 nm near-infrared light. The photothermal and photocatalytic experiments proved that the GO/Ag₃PO₄/CS coating had excellent photothermal and photodynamic properties. In vitro antibacterial experiments showed that the antibacterial rate of the GO/Ag₃PO₄/CS composite coating against Staphylococcus aureus reached 99.81% after 20 minutes irradiation with 808 nm near-infrared light. At the same time, the composite coating had excellent light stability, which could provide stable and sustained antibacterial effect. CONCLUSION GO/Ag₃PO₄/CS coating can be excited by 808 nm near infrared light to produce reactive oxygen species, which has excellent antibacterial activity under light.
Chitosan ; Silver Nitrate ; Titanium ; Anti-Bacterial Agents/pharmacology* ; Coloring Agents

OBJECTIVE: To measure the concentration of bone morphogenetic protein 2 (BMP-2) in demineralized bone matrix (DBM) prepared from different long bones and to evaluate the osteoinductivity of different DBM on MC3T3-E1 cells. METHODS: Different bones from the same cadaver donor were used as the initial materials for making DBM, which were divided into ulna group (uDBM), humerus group (hDBM), tibia group (tDBM), and femur group (fDBM) according to the origins, and boiled DBM (cDBM) was taken as the control group. The proteins of DBM were extracted by guanidine hydrochloride, and the concentrations of BMP-2 were determined by ELISA assay. Then the DBM were co-cultured with MC3T3-E1 cells, the proliferation of MC3T3-E1 cells was observed by cell counting kit 8 (CCK-8) assay. The osteogenic differentiation ability of MC3T3-E1 cells was qualitatively observed by alizarin red, alkaline phosphatase (ALP), and Van Gieson staining, and the osteogenic differentiation ability of MC3T3-E1 cells was quantitatively analyzed by ALP content. Linear regression was used to analyze the effect of BMP-2 concentration in DBM on ALP synthesis. RESULTS: There were significant differences in the concentration of BMP-2 among the DBM groups (P<0.05). The concentrations of BMP-2 in the lower limb long bone were higher than those in the upper limb long bone, and the concentration of BMP-2 in the fDBM group was about 35.5 times that in the uDBM group. CCK-8 assay showed that the cells in each group continued to proliferate within 5 days of co-culture, and the absorbance (A) values at different time points were in the order of cDBM groupP<0.05). Linear regression analysis showed that y^=0.361+0.017x, the effect of BMP-2 concentration in DBM on cellular ALP content was significant (t=3.552, P=0.005); for every 1 ng/g increase in BMP-2 concentration, ALP content would increase by 0.017 [95%CI (0.006, 0.027)] U/100 mL. CONCLUSION The concentration of natural BMP-2 in different long bones varies greatly, and the lower limb long bone is higher than the upper limb long bone. The harvested location of bone material was an important factor affecting the osteoinductivity of DBM.
Alkaline Phosphatase ; Bone Matrix ; Bone Morphogenetic Protein 2 ; Cell Count ; Coloring Agents ; Osteogenesis ; Animals ; Mice

OBJECTIVE: To investigate the effects of melatonin (MT) on bone mass and serum inflammatory factors in rats received ovariectomy (OVX) and to investigate the effects of MT on the levels of inflammatory factors in culture medium and osteogenic ability of bone marrow mesenchymal stem cells (BMSCs) stimulated by lipopolysaccharide. METHODS: Fifteen 12-week-old Sprague Dawley (SD) rats were randomly divided into 3 groups. The rats in Sham group only received bilateral lateral abdominal incision and suture, the rats in OVX group received bilateral OVX, and the rats in OVX+MT group received 100 mg/(kg·d) MT oral intervention after bilateral OVX. After 8 weeks, the levels of serum inflammatory factors [interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α)] were detected using ELISA assay. Besides, the distal femurs were detected by Micro-CT to observe changes in bone mass and microstructure, and quantitatively measured bone volume fraction, trabecular thickness, and trabecular number. The BMSCs were extracted from the femurs of three 3-week-old SD rats using whole bone marrow culture method and passaged. The 3rd-5th passage BMSCs were cultured with different concentrations of MT (0, 1, 10, 100, 1 000 µmol/L), and the cell viability was then detected using cell counting kit 8 (CCK-8) to select the optimal concentration of MT for subsequent experiments. Cells were devided into osteogenic induction group (group A) and osteogenic induction+1/5/10 μg/mL lipopolysaccharide group (group B-D). The levels of inflammatory factors (IL-1β, IL-6 and TNF-α) in cell culture medium were detected using ELISA assay after corresponding intervention. According to the results of CCK-8 method and ELISA detection, the cells were intervened with the most significant concentration of lipopolysaccharide for stimulating inflammation and the optimal concentration of MT with osteogenic induction, defining as group E, and the cell culture medium was collected to detect the levels of inflammatory factors by ELISA assay. After that, alkaline phosphatase (ALP) staining and alizarin red staining were performed respectively in groups A, D, and E, and the expression levels of osteogenic related genes [collagen type Ⅰ alpha 1 chain (Col1a1) and RUNX family transcription factor 2 (Runx2)] were also detected by real time fluorescence quantitative PCR (RT-qPCR). RESULTS: ELISA and Micro-CT assays showed that compared with Sham group, the bone mass of the rats in the OVX group significantly decreased, and the expression levels of serum inflammatory factors (IL-1β, IL-6, and TNF-α) in OVX group significantly increased (P<0.05). Significantly, the above indicators in OVX+MT group were all improved (P<0.05). Rat BMSCs were successfully extracted, and CCK-8 assay showed that 100 µmol/L was the maximum concentration of MT that did not cause a decrease in cell viability, and it was used in subsequent experiments. ELISA assays showed that compared with group A, the expression levels of inflammatory factors (IL-1β, IL-6, and TNF-α) in the cell culture medium of groups B-D were significantly increased after lipopolysaccharide stimulation (P<0.05), and in a concentration-dependent manner. Moreover, the expression levels of inflammatory factors in group D were significantly higher than those in groups B and C (P<0.05). After MT intervention, the expression levels of inflammatory factors in group E were significantly lower than those in group D (P<0.05). ALP staining, alizarin red staining, and RT-qPCR assays showed that compared with group A, the percentage of positive area of ALP and alizarin red and the relative mRNA expressions of Col1a1 and Runx2 in group D significantly decreased, while the above indicators in group E significantly improved after MT intervention (P<0.05). CONCLUSION MT may affect the bone mass of postmenopausal osteoporosis by reducing inflammation in rats; MT can reduce the inflammation of BMSCs stimulated by lipopolysaccharide and weaken its inhibition of osteogenic differentiation of BMSCs.
Female ; Rats ; Animals ; Tumor Necrosis Factor-alpha ; Osteogenesis ; Rats, Sprague-Dawley ; Core Binding Factor Alpha 1 Subunit ; Melatonin/pharmacology* ; Interleukin-6/genetics* ; Lipopolysaccharides/pharmacology* ; Coloring Agents ; Inflammation

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