Synthesis,spectral investigation and biological interphase of drug‐based cytotoxic square pyramidal coordination compounds

We have synthesized ciprofloxacin‐based metal complexes of bipyridine derivatives [Cu(CFL)(Aⁿ)Cl].2H₂O (where CFL = ciprofloxacin and A = bipyridines e.g. A¹ = 4‐(4‐fluorophenyl)‐6‐p‐tolyl‐2,2′‐bipyridine, A⁶ = 4‐(4‐(benzyloxy)phenyl)‐6‐(4‐bromophenyl)‐2,2′‐bipyridine, etc.). The ligands and complexes were characterized using analytical (C, H, N elemental analysis, TGA and magnetic measurement) and spectroscopic methods (¹H and ¹³C NMR, FT‐IR, fast atom bombardment mass and reflectance spectroscopy). The products were evaluated by screening for DNA interaction activity on herring sperm DNA and studies suggest intercalative mode of DNA binding. The antimicrobial activity was determined in terms of minimum inhibitory concentration. Superoxide dismutase mimic studies were performed using the NADH/PMS/NBT system. The brine shrimp bioassay was also carried out to study the in vitro cytotoxic properties of the synthesized metal complexes. Copyright © 2012 John Wiley & Sons, Ltd.     

Supramolecular Tandem Assay for Pyridoxal-5′-phosphate by the Reporter Pair of Guanidinocalix[5]Arene and Fluorescein

Guanidinocalix[5]arene and fluorescein reporter pair has been chosen to set up a supramolecular tandem assay principle based on the differential recognition of pyridoxal-5′-phosphate (the substrate of alkaline phosphatase, ALP), pyridoxal (the product of ALP) and phosphate (the product of ALP). This supramolecular tandem assay system offers an opportunity to monitor the activity of ALP in a label-free, continuous, and real-time manner. More importantly, a calibration curve can be given for selective and quantitative detection of pyridoxal-5′-phosphate (biomarker for several diseases).     

Identification of Broad-Spectrum MMP Inhibitors by Virtual Screening

Matrix metalloproteinases (MMPs) are the family of proteases that are mainly responsible for degrading extracellular matrix (ECM) components. In the skin, the overexpression of MMPs as a result of ultraviolet radiation triggers an imbalance in the ECM turnover in a process called photoaging, which ultimately results in skin wrinkling and premature skin ageing. Therefore, the inhibition of different enzymes of the MMP family at a topical level could have positive implications for photoaging. Considering that the MMP catalytic region is mostly conserved across different enzymes of the MMP family, in this study we aimed to design a virtual screening (VS) workflow to identify broad-spectrum MMP inhibitors that can be used to delay the development of photoaging. Our in silico approach was validated in vitro with 20 VS hits from the Specs library that were not only structurally different from one another but also from known MMP inhibitors. In this bioactivity assay, 18 of the 20 compounds inhibit at least one of the assayed MMPs at 100 μM (with 5 of them showing around 50% inhibition in all the tested MMPs at this concentration). Finally, this VS was used to identify natural products that have the potential to act as broad-spectrum MMP inhibitors and be used as a treatment for photoaging.     

均三嗪衍生物应用于Fe3+和Cu2+的选择性识别研究

合成了2,4-二甲基-6-(4’-N,N-二甲氨基苯乙烯基)-1,3,5-均三嗪(1)和2-苯乙烯基-4,6-二甲基-1,3,5-均三嗪(2)两种化合物,并对其进行了1H NMR,MS,元素分析等表征.采用吸收光谱法研究了金属离子与化合物间的相互作用,结果显示:化合物1对Fe3+和Cu2+表现出高选择性光谱响应,其最大吸收波长由393 nm分别红移至525 nm和513 nm,溶液颜色由黄色变为粉红色.化合物1与Fe3+结合形成1∶1型配合物,其结合常数为1.8×104L mol-1;与Cu2+结合形成2∶1型配合物,其结合常数为2.6×1010L mol-1.化合物2仅对Fe3+呈现显著的光谱变化,其最大吸收波长由304nm红移至357 nm,而Cu2+的加入未引起光谱明显变化,2与Fe3+亦形成1∶1型配合物,结合常数为1.0×105L mol-1.结果表明Fe3+可能与化合物1和2中三嗪N配位,而Cu2+与化合物1中甲氨基中的N配位.同时考察了其它金属离子如Li+,K+,Mg2+,Ca2+,Co3+,Ni2+,Ag+,Cd2+,Hg2+和Zn2+等离子对化合物1和2吸收光谱的影响,结果显示两者光谱均无明显变化,据此提出了高选择性Fe3+,Cu2+的识别体系.     

A microfluidic photolithography for controlled encapsulation of single cells inside hydrogel microstructures

A microfluidic approach to generate hydrogel microstructures inside microchannels for controlled encapsulation of single cells was developed. The method was based on a modified microscope projection photolithography which allowed for the photopolymerization of poly(ethylene glycol) diacrylate (PEG-DA) inside microchannels. Uniform-sized hydrogel microstructures (~50 μm in diameter) were generated one by one with determined positions to encapsulate single cells without losing the viability. Cells of interest could be identified by any kinds of visible labels to be selectively encapsulated inside the formed hydrogel microstructures. Large-scale encapsulation of single cells was achieved with a relatively high efficiency of 80% and the viability of encapsulated cells could be guaranteed by removing the dead cells identified with Trypan blue. This method is simple, fast and convenient to pattern the microchannels with single cells for a wide range of cell-based applications. For demonstration, two intracellular enzyme assays of carboxylesterase were performed to investigate the distribution of enzyme concentrations and the kinetic information within the encapsulated single HepG2 cells.     

Detection of the potential tumor marker of AFP using surface‐enhanced Raman scattering‐based immunoassay

The development of rapid, highly sensitive detection methods for α‐fetoprotein (AFP) is very important. As hepatocellular carcinoma is closely related to the level of AFP in the blood, it is necessary to maintain an AFP concentration below the safety limit. In this paper, we propose a universal, rapid, sensitive, and highly specific immunoassay system utilizing gold nanoparticles (AuNPs) and surface‐enhanced Raman scattering (SERS). This new system features a sandwich structure combining mercaptobenzoic acid‐labeled immunogold nanoparticles with the antigen and the antibody atop a pre‐designed substrate made of a glass slide modified with AuNPs. This SERS‐based immunoassay can detect AFP concentrations as low as 100 pg/ml, which is a significant improvement on the capabilities of the enzyme‐linked immunosorbent assay method. A good linear relationship between the SERS peak intensity and the logarithm of antigen concentrations (from 1 ng/ml to 100 ng/ml) was observed. This technique provides an effective model for the detection of biomarkers in medical diagnostics, criminal investigation, and other fields. Copyright © 2013 John Wiley & Sons, Ltd.     

Exploration of Displacement Reaction/Sorption Strategies in Spectrometric Analysis

Abstract

Displacement reactions are very popular in nature, ranging from texbook knowledge of the Zn-CuSO₄ system to modern functional nucleic acid–involved metal ion displacement. Though synthetic chemistry harvests a lot from displacement reactions, analytical chemistry benefits greatly from various displacement reaction strategies, such as sensitivity improvement. In particular, the use of indicator displacement assay for new sensor development is of great interest worldwide. In this review, we summarize the advances in utilization of displacement reactions for improved spectrometric analysis. The main contents include displacement-based preconcentration schemes for trace metal analysis by analytical atomic spectrometry, indicator displacement assays focusing on the use of advanced nanomaterials, and displacement immunoassays using spectrometric measurements, with 117 references.     

Comparison Between Two Assays for Plasma Cortisol

Abstract

We have compared the results obtained for plasma cortisol when two methods were used to measure this steroid. The first method, a Competitive protein binding (CPB) assay, used transcortin as binding protein for cortisol. The second method is a radioimmunoassay (RIA) utilizing as binding reagent, a specific antibody against cortisol. Nineteen samples were tested covering a wide range of values. The CPB assay consistently overestimated the levels of plasma cortisol compared to the RIA method.     

Pre-Incubation and Low Temperatures in Quantitative Radioreceptor Assays

Abstract

The detection limits of drugs in quantitative RRA are primarily determined by their affinities towards the receptor. Yet, the concentration of radiolabeled ligand, necessary for quantification of receptor-bound drug, increases the theoretical detection limit. Therefore the influences of low temperatures and pre-incubation on the detection limit was studied.     

Determination of Phenols Using Various Peroxidases

Abstract

Peroxidases of different origin — horseradish peroxidase isozyme C, alfalfa and peanut cationic peroxidases, tobacco leaves and novel fungal anionic peroxidases – were used to determine phenol and its analogues. Phenol and resorcinol were shown to be the inhibitors of the peroxidase activity towards o—dianisidine for all the enzymes tested, whereas pyrogallol and hydroquinone caused an appearance of a lag—period on a kinetic curve. The duration of a lag—period was proportional to the effector concentration and could be used to determine it. The novel fungal peroxidase from Phellinus igniarius exhibited the highest sensitivity towards phenols and they could be determined at the 10–6 – 10–7 M concentration levels.