A dual-modality sensing probe of fluorescent and colorimetric for detection of cobalt ion based on silver nanoparticles functionalized rhodamine 6G derivatives.

The combination of fluorescent probe and colorimetric technique has become one of the most powerful analytical methods due to the advantages of visualization, minimal measurement errors and high sensitivity. Hence, a novel dual-modality sensing probe with both colorimetric and fluorescent capabilities was developed for detecting cobalt ions (Co2+) based on homocysteine mediated silver nanoparticles and rhodamine 6G derivatives probe (AgNPs-Hcy-Rh6G2). The fluorescence of the AgNPs-Hcy-Rh6G2 probe turned on due to the opening of the Rh6G2 spirolactam ring in the presence of Co2+ by a catalytic hydrolysis. The fluorescent intensity of probe is proportional to Co2+ concentration in the range of 0.10-50 µM with a detection limit of 0.05 µM (S/N = 3). More fascinatingly, the color of AgNPs-Hcy-Rh6G2 probe changed from colorless to pink with increasing Co2+ concentration, which allowing colorimetric determination of Co2+. The absorbance of AgNPs-Hcy-Rh6G2 probe is proportional to Co2+ concentration in the range from 0.10 to 25 µM with a detection limit of 0.04 µM (S/N = 3). This colorimetric and fluorescent dual-modal method exhibited good selectivity, and reproducibility and stability, holding great potential for real samples analysis in environmental and drug field.

Ultra-trace Ag doped carbon quantum dots with peroxidase-like activity for the colorimetric detection of glucose.

Carbon quantum dots (CQDs) have significant applications in nanozymes. However, previous studies have not elucidated the structure-activity relationship and enzyme mechanism. In this study, we employed a one-step microwave method to synthesize ultra-trace Ag-doped carbon quantum dots (Ag-CQDs). In the presence of hydrogen peroxide (H2O2), we used the oxidative coupling reaction of 3,3',5,5'-tetramethylbenzidine (TMB) to evaluate the intrinsic peroxidase-like activity, kinetics, and mechanism of Ag-CQDs. The trace amount of doped Ag (1.64 %) facilitated electron transfer from the CQDs interior to the surface. The electron transfer triggered the peroxide activity of CQDs, producing hydroxyl radical (·OH), which oxidized the colorless TMB to blue-colored TMB (oxTMB). By coupling with glucose oxidase (GOx), the Ag-CQDs/H2O2/TMB system has been used for colorimetric glucose determination. The system demonstrated a low detection limit (0.17 µM), wide linear range (0.5-5.5 µM), and satisfactory results when fruit juice was analyzed. This study reports a feasible method for the colorimetric detection of glucose by synthesizing ultra-trace Ag-doped carbon quantum dots with peroxidase-mimicking activity.

A novel colorimetric/fluorescent dual-signal probe based on silver nanoparticles functionalized with L-cysteine and rhodamine 6G derivatives for copper ion detection and cell imaging.

The dual-signal probe utilizing functionalized silver nanoparticles (AgNPs) is a promising sensing tool. Herein, a novel colorimetric/fluorescent dual-signal probe (AgNPs-L-Cys-Rh6G2) was fabricated for copper ion (Cu2+) detection and cell imaging by using L-cysteine as a "bridge" to connect AgNPs and rhodamine 6G derivatives. The AgNPs-L-Cys-Rh6G2 probe exhibits a dual-signal response to Cu2+ due to Rh6G2 hydrolysis, resulting in a high fluorescence response and a significant change in color from light yellow to pink under sunlight. The linear detection ranges of the AgNPs-L-Cys-Rh6G2 probe for Cu2+ were 100-450 µM and 150-650 µM using fluorescent and colorimetry methods, respectively. The detection limits were as low as 0.169 µM and 1.36 µM, respectively. Meanwhile, the proposed probe was applied to detect Cu2+ in the actual sediment with satisfactory recovery and low relative standard deviation. Furthermore, the probe was further employed for fluorescence imaging in HeLa cells. In brief, the developed AgNPs-L-Cys-Rh6G2 sensing platform can be used for simultaneous Cu2+ determination and cell imaging.

Optimization of adsorption performance of cerium-loaded intercalated bentonite by CCD-RSM and GA-BPNN and its application in simultaneous removal of phosphorus and ammonia nitrogen.

Excessive phosphorus (P) and ammonia nitrogen (NH3-N) in water bodies can lead to eutrophication of the aquatic environment. Therefore, it is important to develop a technology that can efficiently remove P and NH3-N from water. Here, the adsorption performance of cerium-loaded intercalated bentonite (Ce-bentonite) was optimized based on single-factor experiments using central composite design-response surface methodology (CCD-RSM) and genetic algorithm-back propagation neural network (GA-BPNN) models. Based on the determination coefficient (R2), mean absolute error (MAE), mean square error (MSE), mean absolute percentage error (MAPE), and root mean square error (RMSE), the GA-BPNN model was found to be more accurate in predicting adsorption conditions than the CCD-RSM model. The validation results showed that the removal efficiency of P and NH3-N by Ce-bentonite under optimal adsorption conditions (adsorbent dosage = 1.0 g, adsorption time = 60 min, pH = 8, initial concentration = 30 mg/L) reached 95.70% and 65.93%. Furthermore, based on the application of these optimal conditions in simultaneous removal of P and NH3-N by Ce-bentonite, pseudo-second order and Freundlich models were able to better analyze adsorption kinetics and isotherms. It is concluded that the optimization of experimental conditions by GA-BPNN has some guidance and provides a new approach to explore adsorption performance after optimizing the conditions.

A novel fluorescent "OFF-ON" sensing strategy for Hg (II) in water based on functionalized gold nanoparticles.

Mercury ion (Hg2+) is a heavy metal pollutant that can affect the safety of water environment and endanger human health. A novel detection strategy (GNPs-L-Cys-Rh6G2) for Hg2+ based on a fluorescence "OFF-ON" was proposed. Gold nanoparticles (GNPs) were assembled with l-cysteine (L-Cys), which was used as a "bridge" to link with rhodamine 6G derivatives (Rh6G2). The fluorescence state transition of GNPs-L-Cys-Rh6G2 switching from "OFF"-"ON" was observed because Hg2+ opened the spirolactam ring through a catalytic hydrolysis mechanism. The fluorescence signal of the GNPs-L-Cys-Rh6G2 system mixed with Hg2+ in the concentration range of 10-100 µM was analyzed and determined with a limit of detection (LOD) of 2 µM (S/N = 3). Moreover, the spiked Hg2+ concentration in real water samples were successfully quantified by GNPs-L-Cys-Rh6G2, which was in line with the ideal average recovery rate and relative standard deviation. The proposed strategy exhibited high specificity, sensitivity and stability, providing a novel sensing platform for heavy metal ions detection in water environment.

MicroRNA-320a sensitizes tamoxifen-resistant breast cancer cells to tamoxifen by targeting ARPP-19 and ERRγ.

Tamoxifen represents a major adjuvant therapy to those patients with estrogen receptor-alpha positive breast cancer. However, tamoxifen resistance occurs quite often, either de novo or acquired during treatment. To investigate the role of miR-320a in the development of resistance to tamoxifen, we established tamoxifen-resistant (TamR) models by continually exposing MCF-7 or T47D breast cancer cells to tamoxifen, and identified microRNA(miRNA)-320a as a down-regulated miRNA in tamoxifen resistant cells. Re-expression of miR-320a was sufficient to sensitize TamR cells to tamoxifen by targeting cAMP-regulated phosphoprotein (ARPP-19) and estrogen-related receptor gamma (ERRγ) as well as their downstream effectors, c-Myc and Cyclin D1. Furthermore, progesterone (P4) promoted the expression of miR-320a by repressing c-Myc expression, while estrogen (E2) exerted the opposite effect. These results suggest the potential therapeutic approach for tamoxifen-resistant breast cancer by restorating miR-320a expression or depleting ARPP-19/ERRγ expression.

Transactivation of micrornA-320 by microRNA-383 regulates granulosa cell functions by targeting E2F1 and SF-1 proteins.

Our previous studies have shown that microRNA-320 (miR-320) is one of the most down-regulated microRNAs (miRNA) in mouse ovarian granulosa cells (GCs) after TGF-ß1 treatment. However, the underlying mechanisms of miR-320 involved in GC function during follicular development remain unknown. In this study, we found that pregnant mare serum gonadotropin treatment resulted in the suppression of miR-320 expression in a time-dependent manner. miR-320 was mainly expressed in GCs and oocytes of mouse ovarian follicles in follicular development. Overexpression of miR-320 inhibited estradiol synthesis and proliferation of GCs through targeting E2F1 and SF-1. E2F1/SF-1 mediated miR-320-induced suppression of GC proliferation and of GC steroidogenesis. FSH down-regulated the expression of miR-320 and regulated the function of miR-320 in mouse GCs. miR-383 promoted the expression of miR-320 and enhanced miR-320-mediated suppression of GC proliferation. Injection of miR-320 into the ovaries of mice partially promoted the production of testosterone and progesterone but inhibited estradiol release in vivo. Moreover, the expression of miR-320 and miR-383 was up-regulated in the follicular fluid of polycystic ovarian syndrome patients, although the expression of E2F1 and SF-1 was down-regulated in GCs. These data demonstrated that miR-320 regulates the proliferation and steroid production by targeting E2F1 and SF-1 in the follicular development. Understanding the regulation of miRNA biogenesis and function in the follicular development will potentiate the usefulness of miRNA in the treatment of reproduction and some steroid-related disorders.

MicroRNA-224 is involved in the regulation of mouse cumulus expansion by targeting Ptx3.

MicroRNAs (miRNAs) are indicated to regulate ovarian development in a cell- or stage-specific manner. Our previous study showed that miR-224 is involved in TGF-ß1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production during the transition from the preantral to early antral stage by targeting Smad4. In this study, miR-224 was found to target pentraxin 3 (Ptx3), a gene critical for cumulus expansion during ovulation. In addition, PTX3 was up-regulated in mouse mural GCs and cumulus-oocyte complexes (COCs) by TGF-ß1 treatment, which was partially mediated by miR-224. The effect of miR-224 during ovulation was further examined in vitro and in vivo by construction of an adenovirus-mediated expression vector for miR-224 (Ad-miR-224). In vitro studies demonstrated that miR-224 could perturb cumulus expansion in EGF-stimulated COCs by decreasing PTX3 secretion. In vivo studies also showed that injection of Ad-miR-224 into ovarian bursa decreased PTX3 expression and disrupted ovulation, which led to a decreased number of implantation sites and offspring being born. These results indicate that miR-224 may affect ovulation and subsequent embryo development by targeting Ptx3, suggesting potential roles for miRNAs in offering new treatments for ovulation disorder-associated infertility, or, conversely, designing new contraceptives.

Transcriptional cooperation between p53 and NF-κB p65 regulates microRNA-224 transcription in mouse ovarian granulosa cells.

MicroRNAs (miRNAs) have been indicated to play key roles in ovarian follicular development. However, little is known about how the miRNA gene expression itself is regulated in the mammalian ovary. We previously reported that miR-224 is involved in TGF-ß1-mediated follicular granulosa cell (GC) growth and estradiol (E2) production by targeting Smad4. Here, the transcriptional regulation of miR-224 expression in GCs was further investigated. Our results showed that both the tumor suppressor gene p53 and NF-κB p65 subunit suppressed the TGF-ß1-induced increase in pri-miR-224 expression in GCs. ChIP assays demonstrated that TGF-ß1 enhanced the binding of p53 and p65 to the proximal promoter region of GABAA receptor ε subunit (miR-224 host gene). p53 and p65 transcriptionally cooperated to inactivate the GABAA receptor ε subunit promoter. In addition, p53/p65 could up-regulate Smad4 expression by inhibiting its target miR-224 in GCs which contributed, at least partially, to the effects of miR-224 and Smad4 on GC proliferation and E2 release. Our results provide new data about the interplay between transcription factors involved in GC proliferation and function by cooperatively regulating miRNA expression.

Transactivation of microRNA-383 by steroidogenic factor-1 promotes estradiol release from mouse ovarian granulosa cells by targeting RBMS1.

Our previous studies have shown that microRNA-383 (miR-383) is one of the most down-regulated miRNA in TGF-ß1-treated mouse ovarian granulosa cells (GC). However, the roles and mechanisms of miR-383 in GC function during follicular development remain unknown. In this study, we found that miR-383 was mainly expressed in GC and oocytes of mouse ovarian follicles. Overexpression of miR-383 enhanced estradiol release from GC through targeting RNA binding motif, single stranded interacting protein 1 (RBMS1). miR-383 inhibited RBMS1 by affecting its mRNA stability, which subsequently suppressed the level of c-Myc (a downstream target of RBMS1). Forced expression of RBMS1 or c-Myc attenuated miR-383-mediated steroidogenesis-promoting effects. Knockdown of the transcription factor steroidogenic factor-1 (SF-1) significantly suppressed the expression of Sarcoglycan zeta (SGCZ) (miR-383 host gene), primary and mature miR-383 in GC, indicating that miR-383 was transcriptionally regulated by SF-1. Luciferase and chromatin immunoprecipitation assays revealed that SF-1 specifically bound to the promoter region of SGCZ and directly transactivated miR-383 in parallel with SGCZ. In addition, SF-1 was involved in regulation of miR-383- and RBMS1/c-Myc-mediated estradiol release from GC. These results suggest that miR-383 functions to promote steroidogenesis by targeting RBMS1, at least in part, through inactivation of c-Myc. SF-1 acts as a positive regulator of miR-383 processing and function in GC. Understanding of regulation of miRNA biogenesis and function in estrogen production will potentiate the usefulness of miRNA in the control of reproduction and treatment of some steroid-related disorders.