Transmission of light to the young primate retina: possible implications for the formation of lipofuscin

The purpose of this study was to determine the transmission properties of the anterior segment of young primate eyes and potentially relate those changes to photochemical processes in the retina that lead to the early, rapid formation of lipofuscin. A simple method has been developed to determine the optical properties of the anterior segment of the intact eye. Using this technique, the transmission/absorption properties of primate cadaver eyes were determined. A young primate anterior segment has a maximum absorption at 365nm due to the presence of the O-β-glucoside of 3-hydroxykynurenine in the lens. This is synthesized in the last trimester of gestation. Although this compound filters out most of the UV light from reaching the retina, there is a small window of transmission centered on an absorption minimum at 320nm. This closes by the second decade of life. The window of transmission of UV light to the primate retina may explain the initial accelerated formation of lipofuscin in the young human retina by a photochemical process. This would be exacerbated by any decrease in the ozone layer with concomitant increase in UV-B reaching the earth's surface.     

Near-IR Method for Determining Percent Carbon in Alkylated Materials

Abstract

A simple near-IR transmission spectroscopy method for the determination of percent carbon coverage in trimethylsilylated silicas has been developed. The alkylated silica is slurried in carbon tetrachloride, a solvent with a similar refractive index to silica, to reduce light scattering. Percent carbon is then determined by measuring either the peak height or peak area ratio of the peak at 1180 nm (due to the second overtone of the C-H stretch) to the peak at 1385 nm (due to the overtone of the SiO-H stretch). Comparison with results from elemental analysis permits construction of a correlation curve that can then be used to determine % carbon in unknown samples.     

Study on interaction between cationic polystyrene nanoparticles and DNA, and the detection of DNA by resonance light scattering technology

Monodisperse cationic polystyrene nanoparticles (PS-NPs) were prepared through microemulsion polymerization. Photon correlation spectrometry and transmission electron microscopy revealed that these cationic PS-NPs have a z-average particle size of 30 nm. Size analysis, circular dichroism spectroscopy and transmission electron microscopy indicate that the PS-NPs nanoparticles undergo electrostatic interaction with DNA to form a PS–DNA complex that obviously enhances the resonance light scattering (RLS) signal. A method is presented where the PS-NPs act as a probe for the detection of DNA by RLS. The method is convenient, sensitive, reproducible, and enables high-throughput. The PS-NPs are inexpensive and exhibit low toxicity.     

Age-Related Absorption of the Human Lens in the Near-Ultraviolet Range

The purpose of the present study was to determine the age dependence of the ultraviolet (UV) absorption of the different parts of the human crystalline lens. Cryostat sections of human cadaveric lenses (60 μm) were cut. The UV absorbance of nine samples, derived from different parts of the lens, was determined using a Shimadzu scanning spectrophotometer. The absorbance of the anterior and posterior lens capsules was measured separately. The absorption coefficients were calculated from the measured absorbance and values taken at 280 as well as at 360 nm were compared statistically. ANCOVA analysis of the values taken at 280 and at 360 nm wavelengths shows that correlation between the absorption coefficients and age can be found only in the case of the posterior layers. These results suggest a differential age-dependent increase of the UV absorption of the posterior layers compared to the anterior ones and can be related to the differential protein expression in the anterior and posterior parts. Posterior crystalline lens capsules have higher absorption coefficients than the anterior ones regardless of age.     

Photochemical behavior and Na+,K+-ATPase sensitivity of voltage-sensitive styrylpyridinium fluorescent membrane probes

RH421 is a widely used voltage-sensitive fluorescent membrane probe. Its exposure to continuous illumination with 577 nm light from an Hg lamp leads, however, to an increase in its steady-state fluorescence level when bound to lipid membranes. The increase occurs on the second time scale at typical light intensities and was found to be due to a single-photon excited-state isomerization. Modifications to the dye structure are, therefore, necessary to increase photochemical stability and allow wider application of such dyes in kinetic studies of ion-transporting membrane proteins. The related probe ANNINE 5, which has a rigid polycyclic structure, shows no observable photochemical reaction when bound to DMPC vesicles on irradiation with 436 nm light. The voltage sensitivity of ANNINE 5 was tested with the use of Na+,K+-ATPase membrane fragments. As long as ANNINE 5 is excited on the far red edge of its visible absorption band, it shows a similar sensitivity to RH421 in detecting charge-translocating reactions triggered by ATP phosphorylation. Unfortunately the wavelengths necessary for ANNINE 5 excitation are in a region where the Hg lamps routinely used in stopped-flow apparatus have no significant lines available for excitation.     

Carbazole‐based colorimetric and fluorescent probe for Cu2+ and its utility in bio‐imaging and real water samples

A new carbazole functionalized Schiff base CBM was synthesized and characterized. CBM can selectively recognize Cu²⁺ via UV–vis and fluorescence signal among common biologically relevant metal ions. When Cu²⁺ was added to CBM, there was a significant enhancement at the maximum absorption wavelength of 393 nm and with a distinct blue shift. The maximum emission peak was significantly attenuated by a factor of about 15 times at 535 nm and the blue shift of emission wavelength was observed. When other metal ions were added, there was no remarkable change at the maximum absorption and emission peak. Under the illumination of 365 nm ultraviolet lamp, the color of the CBM solution changed from light blue to dark blue after the addition of Cu²⁺. The combination mechanism of CBM with Cu²⁺ was nicely explored by density functional theory studies. The probe CBM has good cell permeability, fluorescence electron microscopy experiments show that CBM can be used as a fluorescent probe to detect the presence or absence of Cu²⁺ in Hela cells. Furthermore, the probe CBM can also be used for the detection of copper ions in actual water samples.     

A biologically friendly single step method for gold nanoparticle formation

There has been a keen interest for developing a biologically friendly approach for the preparation of gold nanoparticles for their application reasons. A biocompatible, quick and single step method is established for the preparation of gold nanoparticles in lecithin (Egg phosphatidylcholine)/water systems where lecithin itself acts as a reductant for hydrogen tetrachloro aurate (HAuCl(4)) to form the gold nanoparticles. Small gold nanoparticles (5-7 nm in diameter) were prepared in lamellar phases formed by lecithin within 6-7h of HAuCl(4) addition. Sonication of aqueous mixture of lecithin/HAuCl(4) reduces the time of reduction process to seconds when a sonicator with probe (100 W) is used. Most of the particles are found attached to lecithin structures and are comparatively large in size. Some 10nm particles are found attached to small lecithin vesicles (～100 nm) formed during sonication. The nanoparticles formed were stabilized by an anionic surfactant sodium dodecylsulfate (SDS) which proved to be a good stabilizer, the nanoparticles being stable up to six months. To the best of our knowledge, this is the first report where a biological surfactant lecithin itself has acted as a reductant and no other chemical reductants were required for the gold nanoparticle formation. Particles were characterized by Uv-vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Lamellar phases were characterized by a polarizing microscope.     

Application of analytical transmission electron microscopy to the characterization of interlayers in fibre-reinforced composites with ceramic and glass matrices

The microchemistry of interfaces and corresponding interlayers in different fibre-reinforced ceramic and glass composite systems has been investigated by using a dedicated scanning transmission electron microscope demonstrating the potential applicabilities of such an instrument to this large field of materials science. Energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy were used to determine the materials composition on a nanometre scale. Besides analyses performed in the spot mode of the electron probe the distributions of the elements present in the interface region were measured as line profiles across the relevant interface structure by X-ray spectroscopy with a lateral resolution of about 5 nm, even for the detection of a light element as carbon. Moreover, in the composite systems under investigation the two-dimensional element distribution was also attained by energy-filtered imaging. In addition, first results of energy loss near edge structure analyses are presented indicating variations of the chemical bonding of silicon at the interface in a Nicalon fibre/Duran glass composite.     

Differential Light Scattering Spectroscopy for Studying Biospecific Assembling of Gold Nanoparticles with Protein or Oligonucleotide Probes

A new method is proposed for studying biospecific interactions in systems of conjugates of colloidal gold nanoparticles. The method is based on measuring the differential spectra of light scattered at 90° within wavelength range 350–800 nm. Addition of complementary component to bioconjugate probe results in the nanoparticle aggregation that can be monitored by the light scattering or extinction spectra. To this end, we developed a special attachment to a Specord M-40 spectrophotometer and a corresponding measurement procedure called by us the differential light scattering spectroscopy. The method is compared with the common spectrophotometry as applied to colloidal gold conjugates to various polymers including proteins and oligonucleotides. Our experiments with the gold nanoparticles of different sizes showed a higher potential sensitivity of the suggested method as compared to spectrophotometry. It is expected that the differential light scattering spectroscopy can be used to develop sensitive analytical biospecific test for various biopolymers.     

ZnTiO3-TiO2纳米复合材料的光催化性能

通过溶胶 凝胶（Sol-Gel）法制备了ZnTiO3-TiO2纳米复合光催化剂,利用透射电子显微镜、X射线衍射、紫外-可见吸收光谱和ζ电位等测试技术对其形貌、晶体结构及其光谱响应特性进行了表征。 以亚甲基蓝（MB）溶液的脱色降解为模型反应,考察了光源和焙烧温度对该纳米复合材料光催化性能的影响。 结果表明,所得纳米复合材料的催化性能与材料的尺寸、在介质中的分散性能、表面荷电性质等有关。 600 ℃下焙烧3 h所得的ZnTiO3-TiO2纳米复合材料尺寸小（约60 nm）、分散性能好、表面荷负电荷量最高、催化性能最好,且在太阳光下的活性高于紫外光下的。 如太阳光下7 h可使亚甲基蓝（MB）溶液的脱色降解率达到93%,而在紫外光下只有82%;并且其催化活性高于纯TiO2和ZnO的。 该纳米复合催化剂重复使用4次仍能使亚甲基蓝（MB）溶液的脱色降解率在80%以上。 因此,具有较好的光催化稳定性能。     

MEASUREMENT OF CELL LYSIS BY LIGHT SCATTERING

Abstract— A method is presented which is capable of continuously monitoring the degree of hemolysis in erythrocyte suspensions too dilute to be monitored by conventional light transmission techniques. Scattered light is used to non-destructively assess hemolysis in sparse monolayers which are particularly well suited to many photohemolytic studies. The small angle scattering (<10°), measured here, shows a transient decline as cells settle in a culture dish and then is constant if no lysis occurs. Lysis is indicated by a decrease in scattered light to < 20% of initial intensity when lysis is complete. The light used to monitor lysis is restricted to wavelengths longer than 700 nm which is outside the absorption band of many. photosensitizers of current interest, and is a wavelength range at which light scattering is relatively independent of changes in cell volume. In photohemolytic studies with phloxine B lysis values from light scattering are shown to correlate well with lysis values from hemoglobin release. An apparatus is described which is capable of periodically measuring lysis in eight suspensions without intervention by the experimenter.     

Determination of phase transition temperatures of liquid crystals by a light scattering method

A simple analytical system using light scattering (LS) method has been developed to determine phase transition temperatures of liquid crystals (LCs). Intensity changes of the transmission light through a sample were measured as a function of temperature. All LCs and non-LCs showed appreciable changes in the transmission intensity at the phase transition temperature. The transition temperatures determined by the LS method were identical to those by differential scanning calorimetry (DSC).     

基于环状DNA-银纳米簇荧光探针对微囊藻毒素-LR的传感检测

以新型环状DNA为模板, 制备了环状DNA-银纳米簇(Circular DNA-AgNCs)荧光探针, 构建了一种无酶无标记检测微囊藻毒素-LR(MC-LR)的荧光传感分析方法. 设计的环状DNA由MC-LR适体链(Apt)和适体链的互补链(cDNA)杂交形成, 且cDNA可作为DNA模板用于合成AgNCs. 利用透射电子显微镜(TEM)、 紫外-可见光谱(UV-Vis)和荧光光谱(FL)表征了AgNCs的形貌和光学特性.结果表明, 当存在目标物MC-LR时, 由于MC-LR与环状DNA中Apt高特异性和高亲和力结合, 导致环状DNA解体, 释放出的cDNA-AgNCs在610 nm处呈现强荧光. 在优化实验条件下, 环状DNA-AgNCs荧光探针对MC-LR检测的线性范围为0.005~500 μg/L, 检出限为1.7 ng/L(S/N=3). 该荧光探针具有制备简单、 无需任何标记和灵敏度高等特点, 为环境水样中微囊藻毒素-LR的快速和准确测定提供了一种简单、 可靠和有效的方法.     

曙红Y共振光散射探针测定盐酸丙米嗪

在弱酸性介质中,盐酸丙米嗪与曙红Y依靠静电引力和疏水作用力形成离子缔合物,使曙红Y溶液的吸收光谱、荧光光谱和共振光散射光谱发生变化。其中以共振光散射法灵敏度最高。据此,建立了使用曙红Y作为共振光散射探针测定盐酸丙米嗪的新方法。研究了体系的吸收光谱、荧光光谱和共振光散射光谱特征。在最大散射峰364 nm处,测得盐酸丙米嗪的线性范围为0.025～2.5μg/mL,检测限为5.32 ng/mL,并将方法用于药物中盐酸丙米嗪含量的测定。     

ORIENTATION OF RETINYLIDENE CHROMOPHORE OF HYPSORHODOPSIN IN FROG RETINA

Abstract— Hypsorhodopsin and bathorhodopsin were formed in the frog retina by irradiating rhodopsin at liquid He temperature (9 K) with orange light (> 520 nm) and blue light (437 nm), respectively. Hypsorhodopsin was converted to bathorhodopsin in the retina by warming above 32 K in the dark. Similar phenomena were observed in the rod outer segment suspension. A difference spectrum between hypsorhodopsin and bathorhodopsin in the retina produced by warming was almost identical with that in the rod outer segment suspension. This suggests that the transition dipole moment of hypsorhodopsin is parallel to the disk membrane plane which is also parallel to that of bathorhodopsin.     

On the use of single-photon ionization for inorganic surface analysis

Summary A general surface analysis method has been developed based on non-selective photoionization of sputtered or desorbed neutral atoms and molecules above the surface, followed by time-of-flight mass spectrometry. The approach, currently utilizes two main types of ionizing radiation and a variety of desorption probes. For photoionization, coherent untuned sources are used; an intense focused pulsed UV laser beam is used for non-resonant multiphoton ionization to give elemental and limited chemical information, usually used for inorganic analysis; a coherent VUV source is used for single-photon ionization at 118 nm (10.5 eV) produced by frequency tripling of 355 nm light from a Nd:YAG laser. This paper focuses on single-photon ionization for inorganic systems. The desorption probes used are ion, electron, and laser beams as well as thermal desorption. For depth profiling, ion beams are specifically used. Any focused desorption probe beam can provide lateral spatial resolution.     

Optimization of DNA-tagged dye-encapsulating liposomes for lateral-flow assays based on sandwich hybridization

A novel protocol for the synthesis of dye-encapsulating liposomes tagged with DNA oligonucleotides at their outer surface was developed. These liposomes were optimized for use as signal enhancement agents in lateral-flow sandwich-hybridization assays for the detection of single-stranded RNA and DNA sequences. Liposomes were synthesized using the reverse-phase evaporation method and tagged with oligonucleotides by adding cholesteryl-modified DNA probes to the initial lipid mixture. This resulted in a greatly simplified protocol that provided excellent control of the probe coverage on the liposomes and cut the preparation time from 16 hours to just 6 hours. Liposomes were prepared using probe concentrations ranging from 0.00077 to 0.152 mol% of the total lipid, several hydrophobic and polyethylene glycol-based spacers between the cholesteryl anchor and the probe, and liposome diameters ranging from 208 nm to 365 nm. The liposomes were characterized by dynamic light scattering, visible spectroscopy, and fluorescence spectroscopy. Their signal enhancement functionality was compared by using them in lateral-flow optical biosensors for the detection of single-stranded DNA sequences. In these assays, an optimal reporter probe concentration of 0.013 mol%, liposome diameter of 315 nm, and liposome optical density of 0.4–0.6 at 532 nm were found. The spacer length between the cholesteryl anchor and the probe showed no significant effect on the signals in the lateral-flow assays. The results presented here provide important data for the general use of liposomes as labels in analytical assays, with specific emphasis on nucleic acid detection via lateral flow assays.     

Glycine-conjugated porphyrin fluorescent probe with iRGD for live cell imaging

A porphyrin modified by glycine has been synthesized and developed as a near-infrared(NIR) fluorescence probe to detect tumor.Porphyrins'longwavelength emission at ~650 nm can efficiently avoid the spectral crosstalk with Spontaneous fluorescence in the visible light region.A disulfide-based cyclic RGD peptide named iRGD c(CRGDKGPDC),a tumor homing peptide,harbors a cryptic C-end Rule (CendR)motif that is responsible for neuropilin-1(NRP-1)binding and for triggering extravasation and tumor penetration of the peptide to improve the imaging sensitivity and therapeutic efficacy.We used N-hydroxy succinimide as an activator to introduce the glycine methyl ester to detect tumor.We got a porphyrin modified by glycine.The affinity between probe and tumor cell entered GLC-82 cells(human glandular lung cancer cell line)can be observed by Confocal Microscope.The toxicity of probe has been identified by MTT Assay.The summary has been gotten that the porphyrins were nontoxic to GLC-82 cells and glycine modified porphyrin has a good affinity with GLC-82 cells under the iRGD function by our experiment.     

导数光谱法快速测定混合稀土中的钕

光度法单一稀土的测定主要依靠4/电子的跃迁及其受配位场或环境影响后的超灵敏光谱^[1~6],钕与钛铁试剂络合后使其特征峰增强约4倍^[2]可用于测定钕。我们发现此络合物在紫外区尚有二强吸收峰,镧、铈、错、钕、钐、钇的峰位均相同,且摩尔吸光系数很接近,因而可用以代替称量测定总稀土(在255nm)。为提高灵敏度与消除干扰,我们用其三阶导数光谱测钕。据此拟定的快速测定钕法曾试用于合成样及实物,均获得满意的结果。     

Lipid Nanoparticles Traverse Non-Corneal Path to Reach the Posterior Eye Segment: In Vivo Evidence

Lipid-based nanocarriers (LNs) have made it possible to prolong corneal residence time and improve the ocular bioavailability of ophthalmic drugs. In order to investigate how the LNs interact with the ocular mucosa and reach the posterior eye segment, we have formulated lipid nanocarriers that were designed to bear a traceable fluorescent probe in the present work. The chosen fluorescent probe was obtained by a conjugation reaction between fluoresceinamine and the solid lipid excipient stearic acid, forming a chemically synthesized adduct (ODAF, N-(3′,6′-dihydroxy-3-oxospiro [isobenzofuran-1(3H),9′-[9H] xanthen]-5-yl)-octadecanamide). The novel formulation (LN-ODAF) has been formulated and characterized in terms of its technological parameters (polydispersity index, mean particle size and zeta potential), while an in vivo study was carried out to assess the ability of LN-ODAF to diffuse through different ocular compartments. LN-ODAF were in nanometric range (112.7 nm ± 0.4), showing a good homogeneity and long-term stability. A TEM (transmission electron microscopy) study corroborated these results of characterization. In vivo results pointed out that after ocular instillation, LN ODAF were concentrated in the cornea (two hours), while at a longer time (from the second hour to the eighth hour), the fluorescent signals extended gradually towards the back of the eye. From the results obtained, LN-ODAF demonstrated a potential use of lipid-based nanoparticles as efficient carriers of an active pharmaceutical ingredient (API) involved in the management of retinal diseases.