Development of a Fluorescein-Based Probe with an "Off-On" Mechanism for Selective Detection of Copper (II) Ions and Its Application in Imaging of Living Cells.

Copper is a common metallic element that plays an extremely essential role in the physiological activities of living organisms. The slightest change in copper levels in the human body can trigger various diseases. Therefore, it is important to accurately and efficiently monitor copper ion levels in the human body. Recent studies have shown that fluorescent probes have obvious advantages in bioimaging and Cu2+ detection. Therefore, a novel Cu2+ probe (N2) was designed and synthesized from fluorescein, hydrazine hydrate and 5-p-nitrophenylfurfural that is sensitive to and can detect Cu2+ within 100 s. The response mechanism of the N2 probe to Cu2+ was studied by several methods such as Job's plots and MS analysis, which showed that the Cu2+ and the N2 probe were coordinated in a complexation ratio of 1:1. In addition, compared with other cations investigated in this study, the N2 probe showed excellent selectivity and sensitivity to Cu2+, exhibiting distinct fluorescence absorption at 525 nm. Furthermore, in the equivalent range of 0.1-1.5, there is a good linear relationship between Cu2+ concentration and fluorescence intensity, and the detection limit is 0.10 µM. It is worth mentioning that the reversible reaction between the N2 probe and Cu2+, as well as the good biocompatibility shown by the probe in bioimaging, make it a promising candidate for Cu2+ biosensor applications.

Novel Fluorescence Probe toward Cu2+ Based on Fluorescein Derivatives and Its Bioimaging in Cells.

Copper is an important trace element that plays a crucial role in various physiological and biochemical processes in the body. The level of copper content is significantly related to many diseases, so it is very important to establish effective and sensitive methods for copper detection in vitro and vivo. Copper-selective probes have attracted considerable interest in environmental testing and life-process research, but fewer investigations have focused on the luminescence mechanism and bioimaging for Cu2+ detection. In the current study, a novel fluorescein-based A5 fluorescence probe is synthesized and characterized, and the bioimaging performance of the probe is also tested. We observed that the A5 displayed extraordinary selectivity and sensitivity properties to Cu2+ in contrast to other cations in solution. The reaction between A5 and Cu2+ could accelerate the ring-opening process, resulting in a new band at 525 nm during a larger pH range. A good linearity between the fluorescence intensity and concentrations of Cu2+, ranging from 0.1 to 1.5 equivalent, was observed, and the limit detection of A5 to Cu2+ was 0.11 µM. In addition, the Job's plot and mass spectrum showed that A5 complexed Cu2+ in a 1:1 manner. The apparent color change in the A5-Cu2+ complex under ultraviolet light at low molar concentrations revealed that A5 is a suitable probe for the detection of Cu2+. The biological test results show that the A5 probe has good biocompatibility and can be used for the cell imaging of Cu2+.

A Highly Sensitive and Selective Fluorescein-Based Cu2+ Probe and Its Bioimaging in Cell.

Copper is a vital trace metal in human body, which plays the significant roles in amounts of physiological and pathological processes. The application of copper-selective probe has attracted great interests from environmental tests to life process research, yet a few of sensitive Cu2+ tests based on on-site analysis have been reported. In this paper, a novel fluorescein-based fluorescent probe N4 was designed, synthesized, and characterized, which exhibited high selectivity and sensitivity to Cu2+ comparing with other metal ions in ethanol-water (1/1, v/v) solution. The probe N4 bonded with Cu2+ to facilitate the ring-opening, and an obvious new band at 525 nm in the fluorescence spectroscopy appeared, which could be used for naked-eye detection of Cu2+ within a broad pH range of 6-9. Meanwhile, a good linearity between the fluorescence intensity and the concentrations of Cu2+ ranged 0.1-1.5 eq. was observed, and the limit of detection of N4 to Cu2+ was calculated to be as low as 1.20 µm. In addition, the interaction mode between N4 and Cu2+ was found to be 1:1 by the Job's plot and mass experiment. Biological experiments showed that the probe N4 exhibited low biological toxicity and could be applied for Cu2+ imaging in living cells. The significant color shift associated with the production of the N4-Cu2+ complex at low micromolar concentrations under UV light endows N4 with a promising probe for field testing of trace Cu2+ ions.

[Effect of γδ T cells on the Proliferation, Apoptosis and Autophagy of Multiple Myeloma Cells].

AbstractObjective: To investigate the effect of γδ T cells on the proliferation, apoptosis and autophagy of multiple myeloma cells. METHODS: Peripheral blood mononuclear cells (PBMNC) were isolated from healthy volunteers, and stimulated with zoledronic acid (Zol) in combination with rhIL-2. Flow cytometry analysis was used to detected the purity of γδ T cells. γδ T cells were collected and co-cultured with RPMI-8226 or U-266 cells at different effector target ratios. The proliferation of RPMI-8226 or U-266 cell lines were detected by CCK-8. Cell cycle and cell apoptosis were detected by flow cytometry and Western blot．The expressions of autophagy-related proteins were detected by Western blot. RESULTS: γδ T cells can be expanded in vitro. γδ T cells could inhibit the proliferation of RPMI-8226 or U-266 cells, induced cell cycle arrest and promoted apoptosis in an effector target-dependent manner. In addition, γδ T cells could induce autophagy of myeloma cells, inhibited the expression of autophagy-related PI3K, P-AKT and P-mTOR, while increased the expression of AMPK and Beclin-1. CONCLUSION: γδ T cells can inhibit the proliferation of RPMI-8226 and U-266 myeloma cells, induce cell cycle arrest, promote apoptosis, and enhance autophagy in vitro. The mechanism may be related to inhibition of PI3K/AKT/mTOR signaling pathway and/or activation of AMPK/Beclin-1 signaling pathway.

[Research Progress on Regulating Autophagy in the Treatment of Multiple Myeloma --Review].

Abstract　　Autophagy is a process in which cells in eukaryotes degrades abnormal proteins and organelles, thus it possesses important effects on the survival of normal cells and tumor cells. The related studies have shown that autophagy is widely present in the life activities of myeloma cells, which not only protects myeloma cells, but also induces death, and plays an important role in survival, proliferation, invasion and migration of myeloma cells and the treatment of multiple myeloma. This review focuses on the progress of regulating autophagy in the treatment of multiple myeloma.

New rhodamine B-based chromo-fluorogenic probes for highly selective detection of aluminium(iii) ions and their application in living cell imaging.

Two rhodamine B-based fluorescent probes, BOS1 and BOS2, were designed and synthesized with good yields via the condensation reactions between the o-diaminobenzene modified rhodamine core structure (RBO) and salicylaldehyde derivatives. Both the probes exhibited remarkable absorbance-on and fluorescence-on responses to Al3+ over other metal ions in ethanol-water (1 : 9, v/v) medium via the rhodamine ring-opening approach, which can be used for "naked-eye" Al3+ detection over a broad pH range (5-9). The fluorescence intensities of the probes were linear with the Al3+ ion concentration, resulting in a low limit of detection of 1.839 µM (BOS1) and 1.374 µM (BOS2) for Al3+. In addition, the MTT assays and cell imaging experiments of Al3+ in SGC-7901 living cells demonstrated that the probes had negligible cytotoxicity, and were cell permeable and suitable for sensing Al3+ in biological systems.

Development and applications of two colorimetric and fluorescent indicators for Hg2+ detection.

Two rhodamine-active probes RBAI (Rhodamine B-di-Aminobenzene-phenyl Isothiocyanate) and RGAI (Rhodamine 6G-di-Aminobenzene-phenyl Isothiocyanate) were designed, synthesized and characterized. The probes were developed as fluorescent and colorimetric chemodosimeters in ethanol-water solution with a broad pH span (5-10) and high selectivity toward Hg2+ but no significant response toward other common competitive cations. The Hg2+-promoted ring opening of spirolactam of the rhodamine moiety induced cyclic guanylation of the thiourea moiety, which resulted in the dual chromo- and fluorogenic observation (off-on). Cytotoxicity and bioimaging studies by L929 living cells and living mice indicated that the probes were negligible cytotoxicity, cell permeable and suitable for detecting Hg2+ in biological environments. Moreover, the new probes not only displayed excellent abilities for the successful detection of Hg2+ in L929 living cells and living mice but also able to detect Hg2+ by adsorbing on solid surfaces and quantitative detection of Hg2+ in real water samples with good recovery (more than 90%), indicating that they have promising prospect for application for Hg2+ sensing in environmental and biological sciences.

Synthesis and antitumor activity of novel nitrogen mustard-linked chalcones.

A series of nitrogen mustard-linked chalcones were synthesized and evaluated for their antitumor activity in vitro against the K562 and HepG2 cell lines. The aldol condensation of [N,N-bis(chloroethyl)-3-amino]-acetophenone (2) with aromatic aldehydes afforded the nitrogen mustard-linked chalcones. Among the analogs tested, compounds 5e and 5k exhibited significant anti-proliferation activities against K562 cells with IC50 values of 2.55 and 0.61 µM, respectively, which revealed higher cell toxicity than the standard drugs cisplatin (IC50>200 µM) and adriamycin (IC50=14.88 µM). The methoxyl and N,N-dimethyl groups on the B-ring of the chalcone frame enhanced the inhibitory activities against both the K562 and HepG2 cell lines. The structure-activity relationship study indicated that the inhibitory activities significantly varied with the position(s) and species of the substituted group(s).

Copper-catalyzed coupling of oxime acetates with aldehydes: a new strategy for synthesis of pyridines.

Copper-catalyzed coupling of oxime acetates with aldehydes offers a new strategy for the synthesis of highly substituted pyridines. This novel method tolerates a wide range of functionality and allows for rapid elaboration of the oxime acetates into a variety of substituted pyridines.

4-Methyl-2,7-dioxo-3,6-dioxa-1(1,1')-ferrocenacyclo-hepta-phane.

In the title compound, [Fe(C(15)H(14)O(4))], the two cyclo-penta-dienyl (Cp) rings are nearly parallel, making a dihedral angle of 2.6 (1)°. The distance between the centroids of the Cp rings is 3.309 (8) Å. The relative orientation of the two Cp rings is characterized by a torsion angle of -43.99 (6)° defined by the two centroids and the two substituted C atoms.

6-(4-Methyl-phen-yl)-2,10-dioxo-3,9-dioxa-6-aza-1(1,1')-ferrocenacyclo-deca-phane.

In the title compound, [Fe(C(23)H(23)NO(4))], the two cyclo-penta-dienyl (Cp) rings are nearly parallel, with a dihedral angle of 2.1 (1)°. The distance between the centroids of the Cp rings is 3.277 (8) Å. The relative orientation of the two Cp rings is characterized by a torsion angle of -64.3 (3)° defined by the two centroids and two substituted atoms.

4-[(E)-({4-[Bis-(2-hy-droxy-eth-yl)amino]-phen-yl}imino)-meth-yl]phenol.

In the title compound, C(17)H(20)N(2)O(3), the amino N atom is in a planar environment (sum of angles = 360.0°). All hy-droxy H atoms are involved in hydrogen bonding. In the crystal structure, two O-H⋯O and an O-H⋯N(imino) hydrogen bond result in the formation of a three-dimensional network. The latter hydrogen bonding causes distortion of the planarity of the 4-HO-C(6)H(4)-CH=N-C(6)H(4)- fragment by rotation around the =N-C(Ph) bond. The crystal studied was a non-merohedral twin [refined BASF parameter for the major component = 0.5293 (7)].

2,2'-(4-{[(E)-4-Meth-oxy-benzyl-idene]amino}-phenyl-imino)-diethanol.

In the title compound, C(18)H(22)N(2)O(3), the dihedral angle between the aromatic rings is 3.9 (2)°. Both H atoms of the hy-droxy groups are involved in inter-molecular O-H⋯O hydrogen bonding. In the crystal structure, this hydrogen bonding assembles mol-ecules into chains of 2(1) symmetry extending parallel to the b axis. The almost planar (within 0.09 and 0.06 Å) 4-CH(3)O-C(6)H(4)-CH=N-C(6)H(4)- groups are oriented outwards the twofold screw axis.