A Study on Uptake and Localization of Merocyanine 540 (MC540) in Murine Myeloid Leukemia Cells by Confocal Laser Scanning Microscopy (CLSM)

The intracellular localization of merocyanine 540 (MC540), a photosensitizer commonly used in the photo-inactivation of leukemia cells, was studied using confocal laser scanning microscopy. It was found for the first time that MC540 not only localized in the plasma membrane but also in the cytoplasm and the nuclear membrane of the murine myeloid leukemia M1 and WEHI 3B (JCS) cells. Exposure of MC540 treated leukemia cells to light under conditions that could cause photobleaching did not cause the redistribution of cell-bound MC540. Rapid localization of MC540 in the cytoplasm was observed 5 minutes after exposure of leukemia cell to MC540, indicating that MC540 could promptly be internalized by these two leukemia cell lines. In contrast, localization of MC540 was limited only to the plasma membrane of erythrocytes. These results suggest that the binding pattern of MC540 is cell type dependent and may be related to the efficacy of photosenitization in photodynamic therapy.     

高分辨阿达玛变换显微荧光图像分析(Ⅰ)——系统的成像能力及其在单个肿瘤细胞分析中的应用

阿达玛变换(Hadamard transform, HT)是一种类似于傅里叶变换的光谱调制技术, 具有多通道同时检测和多通道成像能力. 实现高分辨HT成像的关键在于阿达玛模板的制作, 阿达玛模板有两种, 即移动式机械编码模板(Movable mechanical mask)和固定式光电模板(Stationary electro-optic mask). 在实际成像方面, 移动模板和固定模板各有优缺点: 前者一般用石英玻璃制作, 对光信号不会因模板吸收而导致信号损失, 因此数据很可靠, 而且模板的制作也较为容易, 但由于采用步进电机驱动而容易导致机械故障, 难以实现快速编码; 后者无移动部件, 无机械故障, 因此系统比较紧凑, 但由于它是由液晶材料制成的(可导致信号损失), 从而限制了其在某些光谱区域的使用. 此外, 它对系统的软件设计要求比前者高, 实现高分辨成像更加困难. 正是由于上述原因, 实现快速、高分辨HT成像具有一定难度, 最近有关HT成像技术的报道极少.     

Phase morphology of blends of polycarbonate with poly(methyl methacrylate-co-cyclohexyl methacrylate), and of polycarbonate with poly(methyl methacrylate) by solid state nuclear magnetic resonance,differential scanning calorimetry,and transmission electron microscopy

The miscibility of polycarbonate (PC) with poly(methyl methacrylate-co-cyclohexyl methacrylate) (PMCHM) and with poly(methyl methacrylate) (PMMA) was studied by nuclear magnetic resonance (NMR) ¹H spin-lattice relaxation time in the rotating frame (¹H T_1p), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). A blend of PC/PMCHM (50/50 wt/wt) with the acrylic component PMCHM, a copolymer of PMMA and poly(cyclohexyl methacrylate) (80/20 wt/wt), shows only one T_1p value, which indicates high miscibility in this blend. A blend of PC/PMMA (50/50 wt/wt) shows two ¹H T_1p values, which are similar to those of the homopolymers PC and PMMA. These results indicate high immiscibility. The “domain size” calculated from NMR results of the miscible blend PC/PMCHM is approximately 40 Å. The results of DSC and TEM are similar to the NMR results. However, TEM results show the presence of 3% PC domains in the PC/PMCHM blend, which are not seen by NMR or DSC. Those PC domains are approximately 500 Å. A strong intramolecular repulsion in the copolymer PMCHM and specific intermolecular interactions between PC and PMMA may explain the miscibility in the PC/PMCHM system. © 1994 John Wiley & Sons, Inc.     

Polymeric microspheres as support to co-immobilized Agaricus bisporus and Trametes versicolor laccases and their application in diazinon degradation

The laccase enzymes of Agaricus bisporus and Trametes versicolor were successfully covalently co-immobilized on poly(glycidyl methacrylate) microspheres. The enzyme load reached after the co-immobilization of both enzymes was 6.75 U g⁻¹ carrier. The resulting biocatalyst showed the combined properties of both immobilized enzymes, increasing their optimum pH and temperature ranges. The storage and operational stabilities were also improved after co-immobilization. In presence of mediator (ABTS) the organophosphate pesticide diazinon was 100% biodegraded after 48 h of reaction with 0.2 U/mL of co-immobilized enzymes (at the two maximum activity pH values: 2.0 and 3.0). In the absence of a mediator, the degradation percentages were above 88%. Data showed that, compared with single enzymatic immobilization, the co-immobilization of the two laccases is an easy, efficient, and low cost alternative to expanding the range of work of the biocatalyst, thereby improving the stability and some biochemical properties to generate a powerful alternative for pesticide degradation in a wide range of conditions.     

Multi-walled BN nanotubes synthesized by carbon-free method

Pure multi-walled BN nanotubes were synthesized via a carbon-free chemical vapor deposition process using boron and gallium oxide mixture as reaction precursor. Transmission electron microscopy was used to investigate their structure, morphology and defects. The wall deformation, dependent on tube diameter, was observed and explained in terms of strain relaxation of bond rotation. Opposed to carbon nanotubes, bending of BN nanotubes typically results in fracture at their concave side. Ring defect-related mechanism was proposed to interpret the fracture. The ring defects also result in the formation of a nanocone with 300° disclination. The nanocones end up with BN nanotubes exhibiting the small innermost shell ∼0.4 nm in diameter.     

Microscopic study of ultra-thin gold layers on polyethyleneterephthalate

Continuous and discontinuous gold layers sputtered on polyethyleneterephthalate (PET) were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM) and by reflection of microwave radiation. The changes in the surface morphology of the continuous and discontinuous gold layers as a function of the sputtering time were clearly observed by AFM technique. SEM imaging of very thin gold layers was adversely affected by specimen charging. For medium sputtering times, when a continuous gold coverage is already formed, the SEM technique still show the presence of regions with very thin gold coverage which gradually disappear at longer sputtering times. Both, the AFM and SEM techniques confirmed that in the course of the gold deposition the initially small gold clusters grow and finally associate in a continuous layer. It was shown that the sub-microne metallic structures could be modeled by artificial, significantly larger structures prepared on PET by lithographic etching.     

Vibrational study of tamoxifen citrate polymorphism

The trans isomer of (Z)-2-[p-(1,2-diphenyl-butenyl)phenoxy]-N,N-dimethyletylamine (tamoxifen) is well known for its endocrine activity as an antiestrogenic agent. Its citrate salt, a widely used pharmaceutical agent, appears in three main polymorphic forms, two of which are well known (I and II) and another form not yet well evidenced.

A vibrational study has been conducted for identifying the two known polymorphic forms of tamoxifen citrate (I and II) and for characterising the other form (form III) examined in this study.

Other techniques for the characterization of the different polymorphs, such as XRDP, have been used.     

The variable projection algorithm in time-resolved spectroscopy,microscopy and mass spectrometry applications

Nonlinear least squares optimization problems in which the parameters can be partitioned into two sets such that optimal estimates of parameters in one set are easy to solve for given fixed values of the parameters in the other set are common in practice. Particularly ubiquitous are data fitting problems in which the model function is a linear combination of nonlinear functions, which may be addressed with the variable projection algorithm due to Golub and Pereyra. In this paper we review variable projection, with special emphasis on its application to matrix data. The generalization of the algorithm to separable problems in which the linear coefficients of the nonlinear functions are subject to constraints is also discussed. Variable projection has been instrumental for model-based data analysis in multi-way spectroscopy, time-resolved microscopy and gas or liquid chromatography mass spectrometry, and we give an overview of applications in these domains, illustrated by brief case studies.     

Iron nanoparticles produced by high-energy ball milling

In this investigation, the chemical and structural characteristics of Fe nanoparticles synthesized by high-energy ball milling have been explored. After the milling process the nanoparticles were collected using a magnetic field. The structure, morphology and composition of the powders were obtained using high-resolution electron microscopy. HREM images confirmed the nanoparticles’ presence with approximately 2–4 nm in size. It was found that using this method allowed the formation of nanoparticles in a smaller size range than other synthesis methods. Also, it was confirmed by HREM images that the obtained nanoparticles were mainly of the fcc nature and some of them of the MTP type.     

Identification of archaeological ivories using FT-Raman spectroscopy

FT-Raman spectroscopy has been used successfully for the non-destructive identification of modern ivories and is evaluated here for the identification of osseous materials from archaeological sites. Results on archaeological ivories are reported and the problems faced in matching FT-Raman spectra to standards for the validation of these materials are highlighted. Archaeological specimens of different dates, provenance and taphonomic history, including both conserved and unconserved items, have been analysed.