Biosorption of thorium onto Chlorella Vulgaris microalgae in aqueous media.

Thorium biosorption by a green microalga, Chlorella Vulgaris, was studied in a stirred batch reactor to investigate the effect of initial solution pH, metal ion concentration, biomass dosage, contact time, kinetics, equilibrium and thermodynamics of uptake. The green microalgae showed the highest Th adsorption capacity at 45 °C for the solution with a thorium concentration of 350 mg L-1 and initial pH of 4. The amount of uptake raised from 84 to 104 mg g-1 as the temperature increased from 15 to 45 °C for an initial metal concentration of 75 mg L-1 at pH 4. Transformation Infrared Spectroscopy (FTIR) was employed to characterize the vibrational frequency changes for peaks related to surface functional groups. Also, the scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to determine the morphological changes and elemental analysis of the biosorbent before and after the sorption process. The Langmuir isotherm was in perfect agreement with the equilibrium empirical data of thorium biosorption and the highest sorption capacity of the Chlorella Vulgaris microalgae was determined as 185.19 mg g-1. Also, the results of kinetic studies show that the thorium biosorption process follows a pseudo-second-order kinetic model. The negative value of ΔG0 indicates spontaneity and the positive values of ΔH0 indicate the endothermic nature of the adsorption process.

THQ-Xanthene: An Emerging Strategy to Create Next-Generation NIR-I/II Fluorophores.

Near-infrared fluorescence imaging is vital for exploring the biological world. The short emissions (<650 nm) and small Stokes shifts (<30 nm) of current xanthene dyes obstruct their biological applications since a long time. Recently, a potent and universal THQ structural modification technique that shifts emission to the NIR-I/II range and enables a substantial Stokes shift (>100 nm) for THQ-modified xanthene dyes is established. Thus, a timely discussion of THQ-xanthene and its applications is extensive. Hence, the advent, working principles, development trajectory, and biological applications of THQ-xanthene dyes, especially in the fields of fluorescence probe-based sensing and imaging, cancer theranostics, and super-resolution imaging, are introduced. It is envisioned that the THQ modification tactic is a simple yet exceptional approach to upgrade the performance of conventional xanthene dyes. THQ-xanthene will advance the strides of xanthene-based potentials in early fluorescent diagnosis of diseases, cancer theranostics, and imaging-guided surgery.

Cysteine-Activatable Near-Infrared Fluorescent Probe for Dual-Channel Tracking Lipid Droplets and Mitochondria in Epilepsy.

Dual-channel fluorescent probes could respond to a specific target and emit different wavelengths of fluorescence before and after the response. Such probes could alleviate the influence caused by the variation of the probe concentration, excitation intensity, and so on. However, for most dual-channel fluorescent probes, the probe and fluorophore faced spectral overlap, which reduced sensitivity and accuracy. Herein, we introduced a cysteine (Cys)-responsive and near-infrared (NIR) emissive AIEgen (named TSQC) with good biocompatibility to dual-channel monitor Cys in mitochondria and lipid droplets (LDs) during cell apoptosis through wash-free fluorescence bio-imaging. TSQC can label mitochondria with bright fluorescence around 750 nm, and after reacting with Cys, the reaction product TSQ could spontaneously target LDs with emissions around 650 nm. Such spatially separated dual-channel fluorescence responses could significantly improve detection sensitivity and accuracy. Furthermore, the Cys-triggered dual-channel fluorescence imaging in LDs and mitochondria during apoptosis induced by UV light exposure, H2O2, or LPS treatment is clearly observed for the first time. Besides, we also report here that TSQC can be used to image subcellular Cys in different cell lines by measuring the fluorescence intensities of different emission channels. In particular, TSQC shows superior utility for the in vivo imaging of apoptosis in acute and chronic epilepsy mice. In brief, the newly designed NIR AIEgen TSQC can respond to Cys and separate two fluorescence signals to mitochondria and LDs, respectively, to study Cys-related apoptosis.

Evaluation of peroxynitrite fluxes in inflammatory mice with a ratiometric fluorescence probe.

Inflammation is a critical physiological process in the human body, which is closely related to numerous disorders and cancers. ONOO- is generated and functionalized in the inflamed process, but the roles of ONOO- are still blurred. To illuminate the roles of ONOO-, we fabricated an intramolecular charge transfer (ICT)-based fluorescence probe, HDM-Cl-PN, for the ratiometric determination of ONOO- in the inflamed mouse model. The probe displayed a gradual fluorescence increase at 676 nm and a fluorescence drop at 590 nm toward 0-10.5 µM ONOO-, and the ratio of 676 nm fluorescence and 590 nm fluorescence varied from 0.7 to 24.7. The significantly changed ratio and favorable selectivity ensure the sensitive detection of subtle changes in cellular ONOO-. Thanks to the excellent sensing performance, HDM-Cl-PNin vivo ratiometrically visualized ONOO- fluctuations in the LPS-triggered inflammatory process. Overall, this work not only expatiated the rational design for a ratiometric ONOO- probe but also built a bridge to investigate the connections between ONOO- and inflammation in living mice.

Engineering Sandwiched Nanochannel Aptasensor for Efficiently Screening Cancer Cells.

Cancer cells are a class of important tumor biomarkers and are closely related to tumorous progression. It is urgent to develop a sensitive and highly efficient method for the rapid and accurate detection of cancer cells. Herein, an aptamer sandwiched nanochannel electrochemical sensor was established for the highly selective determination of cancer cells. By virtue of the porous nanochannels as the filter platform and immobilized with DNA aptamers for specifically capturing the cancer cells, the nanochannel-based electrochemical sensor denotes excellent performance for MCF-7 screening, and allowing a low limit of detection of 36 cells mL-1 . The nanochannels-based sandwich structure aptasensor not only presents an efficacious and reliable approach for cancer cell detection but also provides great advantage for preventing electrode passivation in the process of biomarkers analysis.

Hsa_circ_0081534 facilitates malignant phenotypes by sequestering miR-874-3p and upregulating FMNL3 in nasopharyngeal carcinoma.

OBJECTIVE: Circular RNAs (circRNAs) are connected to nasopharyngeal carcinoma (NPC) development and progression. CircRNA hsa_circ_0081534 (circ_0081534) has been reported to be associated with NPC progression, but its underlying regulatory mechanisms are largely unknown. Thus, the study aims to investigate the mechanism by which circ_0081534 regulates NPC progression. METHODS: Quantitative reverse transcription polymerase chain reaction was conducted to detect circ_0081534 expression. Loss-of-function assays were conducted to evaluate the role of circ_0081534, including 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) staining, colony formation, flow cytometry, transwell, western blotting, and xenograft assays. Targeting relationship was identified through dual-luciferase reporter assay and RNA immunoprecipitation. RESULTS: Our data exhibited that circ_0081534 was upregulated in NPC samples and cells. Knockdown of circ_0081534 repressed NPC cell proliferation, migration, invasion, EMT, and triggered NPC cell apoptosis. Also, circ_0081534 silencing decreased NPC cell growth in xenograft models. Circ_0081534 functioned as a miR-874-3p sponge, and downregulation of miR-874-3p alleviated the suppressive effects of circ_0081534 silencing on NPC cell malignant phenotypes. MiR-874-3p targeted FMNL3, and circ_0081534 regulated FMNL3 expression through serving as a miR-874-3p sponge. Upregulation of FMNL3 relieved the inhibitory effects of circ_0081534 downregulation on NPC cell malignant phenotypes. CONCLUSION: circ_0081534 interference repressed NPC progression partly by modulating the miR-874-3p/FMNL3 axis.

Activatable Two-Photon Near-Infrared Fluorescent Probe Tailored toward Peroxynitrite In Vivo Imaging in Tumors.

A malignant tumor remains one of the leading causes of deaths across the world. Thus, diagnosis of tumor development with noninvasive visualizing methods is significant for tumor therapy. Herein, an activatable two-photon NIR fluorescent probe DHQ-Rd-PN for in vivo imaging of peroxynitrite in a tumor was elaborately designed. The probe demonstrated an increased NIR emission in response to peroxynitrite in vitro, which ensured that the probe detects ONOO- in cell and in vivo. Cellular imaging results disclosed that the probe was competent to detect adscititious ONOO- level change in HeLa cells, as well as endogenous ONOO- concentration in lipopolysaccharides (LPS) and IFN-γ-stimulated RAW 264.7 cells. Additionally, zebrafish in vivo imaging revealed that the probe accumulated in the pancreas and was lightened up by the addition of ONOO-. Remarkably, the probe can be harnessed to image an ONOO- production profile in xenograft 4T1 tumor mice by both one-photon and two-photon in vivo fluorescence imaging. Benefiting with the two-photon excitable properties and NIR emissive properties, the probe can be used for noninvasive in vivo imaging of ONOO- in the onset and development of tumors for the first time. This work provided a noninvasive and efficient detection method for ONOO- in a tumor, which would find more applications in tumor diagnosis and therapies.

Development of a Silicon-Rhodamine Based Near-Infrared Emissive Two-Photon Fluorescent Probe for Nitric Oxide.

Two-photon (TP) fluorescent probes are potential candidates for near-infrared (NIR) imaging which holds great promise in biological research. However, currently, most TP probes emit at wavelength <600 nm, which impedes their practical applications. In this work, we explored the TP properties of a silicon-rhodamine (SiR) derivative and hence developed the first SiR scaffold based "NIR-to-NIR" TP probe (SiRNO) for nitric oxide (NO). SiRNO exhibited high sensitivity and specificity, as well as fast response for NO detection. It was able to track the subtle variation of intracellular NO content in live cells. Owing to the NIR excitation and emission, SiRNO enabled the detection of NO in situ in the xenograft tumor mouse model, revealing the NO generation during the tumor progression. This work indicates that SiR can be an ideal platform for the development of NIR emissive TP probe and may thus promote the advancement of NIR imaging.

A ratiometric two-photon fluorescent probe for imaging hydrogen sulfide in lysosomes.

Hydrogen sulfide (H2S) is a kind of gaseous signalling molecule that plays pivotal role in various biological processes. So far, it is still a challenge to develop convenient and reliable methods for H2S detection in lysosomes. Herein, we developed a novel ratiometric two-photon fluorescent probe LR-H2S for imaging H2S in lysosomes. Upon the addition of H2S (using Na2S as a donor) to LR-H2S in buffer solution, the azide group is reduced to amino group and subsequently the carbamate ester is cleaved by 1,6-elimination, resulting in a fluorescence emission increase at 541nm and a concomitant emission decrease at 475nm. Under two-photon excitation of 840nm, an 80-fold fluorescence ratio (F541/F475) enhancement was observed with a wide linear range of 25-2500µM. The detection limit was calculated to be 0.70µM based on 3σ/k method, indicating that the probe can detect H2S with a high sensitivity. The probe also shows excellent selectivity toward H2S among other biological interference species and features with low cytotoxicity and favorable two-photon properties. Furthermore, LR-H2S can easily localize in lysosomes and vividly illuminate endogenous/exogenous H2S level and distribution in lysosomes of living SGC-7901 cells.