Chimeric Aptamers-Based and MoS2 Nanosheet-Enhanced Label-Free Fluorescence Polarization Strategy for Adenosine Triphosphate Detection.

Adenosine triphosphate (ATP) as a primary energy source plays a unique role in the regulation of all cellular events. The necessity to detect ATP requires sensitive and accurate quantitative analytical strategies. Herein, we present our study of developing a MoS2 nanosheet-enhanced aptasensor for fluorescence polarization-based ATP detection. A bifunctional DNA strand was designed to consist of chimeric aptamers that recognize and capture ATP and berberine, a fluorescence enhancer. In the absence of ATP, the DNA strand bound to berberine will be hydrolyzed when Exonuclease I (Exo I) is introduced, releasing berberine as a result. In contrast, when ATP is present, ATP aptamer folds into a G-quadruplex structure; thus, the complex can resist degradation by Exo I to maintain berberine for fluorescent detection purpose. In addition, to magnify the fluorescence polarization (FP) signal, MoS2 nanosheets were also adopted in the system. This nanosheets-enhanced FP strategy is simple and facile which does not require traditional dye-labeled DNA strands and complex operation steps. The developed fluorescence polarization aptasensor showed high sensitivity for the quantification of ATP with a detection limit of 34.4 nM, performing well both in buffer solution and in biological samples.

Microwave-assisted one-step extraction-derivatization for rapid analysis of fatty acids profile in herbal medicine by gas chromatography-mass spectrometry.

A rapid and practical microwave-assisted one-step extraction-derivatization (MAED) method was developed for gas chromatography-mass spectrometry analysis of fatty acids profile in herbal medicine. Several critical experimental parameters for MAED, including reaction temperature, microwave power and the amount of derivatization reagent (methanol), were optimized with response surface methodology. The results showed that the chromatographic peak areas of total fatty acids and total unsaturated fatty acids content obtained with MAED were markedly higher than those obtained by the conventional Soxhlet or microwave extraction and then derivatization method. The investigation of kinetics and thermodynamics of the derivatization reaction revealed that microwave assistance could reduce activation energy and increase the Arrhenius pre-exponential factor. The MAED method simplified the sample preparation procedure, shortened the reaction time, but improved the extraction and derivatization efficiency of lipids and reduced ingredient losses, especially for the oxidization and isomerization of unsaturated fatty acids. The simplicity, speed and practicality of this method indicates great potential for high throughput analysis of fatty acids in natural medicinal samples.

Analysis of fatty acids in A. szechenyianum Gay. by microwave-assisted extraction and gas chromatography-mass spectrometry.

INTRODUCTION: Aconitum szechenyianum Gay. is a traditional Chinese medicinal herb with the detumescent and styptic effects and antitumor activity. There have been only a few researches on its chemical components, but no detailed report has appeared on its fatty acids. OBJECTIVE: To develop a simple and effective method for the extraction of fatty acids from A. zechenyianum Gay. and then to investigate the fatty acid components. METHODOLOGY: Microwave-assisted extraction (MAE) was optimized with response surface methodology, and the fatty acid compositions of extract were determined by GC-MS with previous derivatisation to fatty acid methyl esters (FAMEs). The results were compared with that obtained by classical Soxhlet extraction (SE). RESULTS: Compared with SE, MAE showed significantly higher fatty acid yields, shorter extraction time, and lower energy and solvent consumption. The major fatty acids in A. szechenyianum Gay. are linoleic acid, palmitic acid, linolenic acid, oleic acid and stearic acid, and the unsaturated fatty acids occupy 66.4% of the total fatty acids.

[Optimization of microwave-assisted extraction with RSM and HPLC determination for three iridoid glycosides in Cornus officinalis].

OBJECTIVE: To establish a method of microwave-assisted extraction and high performance liquid chromatographic (HPLC) for simultaneous determination of three iridoid glycosides including loganin, sweroside and cornuside in Cornus officinalis. METHODS: The extraction conditions of microwave power,ethanol concentration, liquid to sample ratio were optimized with a response surface methodology (RSM); Three constituents were separated on an Agilent TC-C18 column by gradient elution using acetonitrile and water as the mobile phase. The flow rate was 1.0 mL/min. The detection wave length was 240 nm. RESULTS: The optimal conditions of microwave extraction were as follows: microwave power 400 W, ethanol concentration 72%, liquid to sample ratio 15 mL/g, the extraction time 10 min, the extraction times 2; The HPLC peak areas of all the constituents showed good linearity (r>0.9994) in the range of the tested concentration,the average recoveries of the method were 98.68%, 98.24% and 98.29%, respectively. CONCLUSIONS: The established method of microwave-assisted extraction and HPLC simultaneously determination has the advantages of convenient, precision and reliability. It can be used in simultaneous determination of three iridoid glycosides in Cornus officinalis.

A magnetic hyperbranched polyamide amine-based quick, easy, cheap, effective, rugged and safe method for the detection of organophosphorus pesticide residues.

Magnetic hyperbranched polyamide amine (MHPA) was successfully prepared and applied as a QuEChERS adsorbent to the gas chromatograph-mass spectrometer (GC-MS) detection of organophosphorus pesticides (OPPs) in orange juice. Abundant in amino types and the structure of hyperbranched organic chains make MHPA to possess the clean-up function integrating classic clean-up agent primary secondary amine (PSA) with C18 modified silica, and the magnetic property makes the operation easier and more time-saving. Compared the performance with classical clean-up agents of PSA and C18, better results were obtained with MHPA as adsorbent for the detection of 11 OPPs. Recoveries ranged from 75.2 to 116.2% with the relative standard deviation (RSD) of 4.1-18.9% and the limit of detection (LOD) of 0.74-8.16 ng/g. Results showed that using MHPA as adsorbent for QuEChERS sample preparation is an effective alternative with simplicity and rapidity.

An efficient ratiometric fluorescence sensor based on metal-organic frameworks and quantum dots for highly selective detection of 6-mercaptopurine.

The development of a simple and accurate quantitative method for the determination of 6-mercaptopurine (6-MP) is of great importance because of its serious side effects. Ratiometric fluorescence (RF) sensors are not subject to interference from environmental factors, and exhibit enhanced precision and accuracy. Therefore, a novel RF sensor for the selective detection of 6-MP was developed based on a dual-emission nanosensor. The nanosensor was fabricated by combining a blue-emission metal-organic framework (MOF) NH2-MIL-53(Al) (λem=425nm) with green-emission 3-mercaptopropionic acid-capped CdTe quantum dots (MPA-CdTe QDs) (λem=528nm) under a single excitation wavelength (335nm). Upon addition of 6-MP, the fluorescence of NH2-MIL-53(Al) in the nanohybrid was selectively quenched due to strong inner filter effects, while the fluorescence of the MPA-CdTe QDs was enhanced. The novel RF sensor exhibited higher selectivity towards 6-MP than CdTe QDs alone, and higher sensitivity than MOFs alone. 6-MP could be detected in the range of 0-50µM with a detection limit of 0.15µM (S/N=3). The developed sensor was applied for the determination of 6-MP in human urine samples and satisfactory results were obtained. Overall, a novel and efficient fluorescence-based method was developed for the detection of 6-MP in biosamples.

Preparation of chitosan/silk fibroin/hydroxyapatite porous scaffold and its characteristics in comparison to bi-component scaffolds.

Composite porous scaffolds have attracted extensive attention in the biomedical material field. The aim of this research was to prepare a novel tri-component composite porous scaffold and to evaluate its relevant properties. The porous scaffold was composed of chitosan (CS), silk fibroin (SF), and nanohydroxyapatite particles (nHA), which we named CS/SF/nHA scaffold and prepared via salt fractionation method combined with lyophilization. The porous structure was achieved using a porogen (salt), and the pore size was controlled by the size of porogen. To evaluate the characteristics of the tri-component scaffold, three bi-component scaffolds, CS/SF, CS/nHA, and SF/nHA, were simultaneously prepared for comparison. The scaffolds were subjected to morphological, micro-structural, and biodegradation analyses. Results demonstrated that all of the scaffolds had pore sizes of 100-300 µm and a porosity of 90.5-96.1%. The biodegradation characteristics of all scaffolds meet the requirements of good biomedical materials. The investigation of the mechanical properties showed that the tri-component scaffold has better properties than the bi-component scaffolds. The in vitro biocompatibility with osteoblast-like MG-63 cells showed that all the scaffolds are suitable for cell attachment and proliferation; however, the CS/SF/nHA composite porous scaffold is much more effective than the others.

Three-dimensional cell bioreactor coupled with high performance liquid chromatography-mass spectrometry for the affinity screening of bioactive components from herb medicine.

An efficient and convenient method, three-dimensional (3-D) cell bioreactor coupled with high performance liquid chromatography-mass spectrometry was developed for affinity screening and analysis of multiple bioactive components from herbal medicines. Cancer cells were cultured on a porous scaffold to form a 3-D cell bioreactor. After interacting with live and fixed cells, the HPLC fingerprinting chromatograms of herbal medicine extract were compared to evaluate the binding properties of herbal components on cells. Model anticancer drugs (paclitaxel and resveratrol) and non-anticancer drugs (ketoprofen and penicillin G) were chosen to investigate the feasibility. When cell-drug interaction time was 30 min, the binding degrees of paclitaxel and resveratrol (each 15 µg/ml) were 82.2±7.2% and 66.1±4.1%, and for ketoprofen and penicillin G (each 15 µg/ml) were less than 3%. This method was used to screen bioactive components from Polygonum cillinerve (Nakai) Ohwi (PCO) extract, and the binding degrees of two main components in PCO extract (10 µg/ml), aristolochic acid A and aristolochic acid B, were 63.0±5.1% and 18.8±0.9%, respectively. These results demonstrated that this method was highly specific, efficient and convenient for affinity screening and analysis of bioactive components interacted with cells.