Targeted optical injection of gold nanoparticles into single mammalian cells

We present an all optical technique for the targeted delivery of single 100 nm diameter gold nanoparticles into a specified region of the interior of an individual mammalian cell through a combination of optical tweezing and optical injection. The internalisation of the nanoparticle is verified by confocal laser scanning microscopy and confocal laser scanning reflectance microscopy. This represents the first time that nano sized particles have been tweezed and optically injected into mammalian cells using only light, and provides a novel methodology for internalising nanosphere based biosensors within specific intracellular regions of a mammalian cell. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Using Optics to Measure Biological Forces and Mechanics

Spanning all size levels, regulating biological forces and transport are fundamental life processes. Used by various investigators over the last dozen years, optical techniques offer unique advantages for studying biological forces. The most mature of these techniques, optical tweezers, or the single-beam optical trap, is commercially available and is used by numerous investigators. Although technical innovations have improved the versatility of optical tweezers, simple optical tweezers continue to provide insights into cell biology. Two new, promising optical technologies, laser-tracking microrheology and the optical stretcher, allow mechanical measurements that are not possible with optical tweezers. Here, I review these various optical technologies and their roles in understanding mechanical forces in cell biology.     

皮肤的光学模型

基于人体皮肤的组织结构,光在皮肤组织中的传输特性以及皮肤各层的组织光学参数,建立了正常皮肤的光学模型,介绍了该模型中的组织光学参数的确定方法。本文建立的皮肤组织光学模型及其方法,可应用于皮肤光学基础与临床的其它研究中。     

一种微距测量组织光学参数的方法

测量生物组织的光学参数是近红外光学检测(NIR)的主要任务之一,然而常规的近红外光学检测由于受扩散近似的限制,测量的距离一般大于2cm-3cm。本文从提高近红外光学检测空间分辨率的角度,设计了一种可用于测量生物组织局部、浅表光学参数的方法。通过使用光纤探针,实现了在微小光源-探测器间距时(＜1mm)测量组织光学参数。模型实验的结果表明该方法可反映生物组织中吸收系数及散射系数的变化率。     

Integrating photoacoustic microscopy with other imaging technologies for multimodal imaging

As a hybrid optical microscopic imaging technology, photoacoustic microscopy images the optical absorption contrasts and takes advantage of low acoustic scattering of biological tissues to achieve high-resolution anatomical and functional imaging. When combined with other imaging modalities, photoacoustic microscopy-based multimodal technologies can provide complementary contrast mechanisms to reveal complementary information of biological tissues. To achieve intrinsically and precisely registered images in a multimodal photoacoustic microscopy imaging system, either the ultrasonic transducer or the light source can be shared among the different imaging modalities. These technologies are the major focus of this minireview. It also covered the progress of the recently developed penta-modal photoacoustic microscopy imaging system featuring a novel dynamic focusing technique enabled by OCT contour scan.     

鲍氏层孔菌培养条件的研究

本项研究对分离于野外的鲍氏层孔菌从不同的温度、pH值以及不同的碳源和氮源的营养成分三方面进行室内培养,其结果显示鲍氏层孔菌营养菌丝生长的最适温度为28℃;最佳碳源为甘露醇和葡萄糖;最佳氮源为蛋白胨,其次为牛肉膏;而pH值在6.0-8.0的范围内变化对其菌丝体生长影响不大。这些结果为将来大规模人工培植鲍氏层孔菌提供了很好的指导作用。     

Synthesis and luminescence properties of a blue-emitting Sr(3.5) Y(6.5) O(2) (PO(4) )(1.5) (SiO(4) )(4.5) :Eu(2+) phosphor

A novel blue‐emitting Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:Eu²⁺ phosphor was synthesized via a solid‐state reaction. Powder X‐ray diffraction (XRD) analysis demonstrated that the Sr_3.5Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5 host had a hexagonal crystal structure in the space group P6₃/m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as‐prepared phosphor showed a blue emission and all the main emission peaks were located at around 466 nm for different excitation wavelengths of 297, 333 and 391 nm. The temperature dependence of the photoluminescence property was investigated in the range 20–250 °C, and the emission intensity decreased to 71% of the initial value at room temperature on increasing the temperature to 150 °C. According to the classical theory of fluorescent thermal quenching, the activation energy (ΔE) for the thermal quenching luminescence of the as‐prepared Sr_3.45Y_6.5O₂(PO₄)_1.5(SiO₄)_4.5:0.05Eu²⁺ phosphor was determined to be 0.20 eV. Copyright © 2011 John Wiley & Sons, Ltd.     

Label‐free bioanalysis of Leishmania infantum using refractive index tomography with partially coherent illumination

In this work, we report the use of refractive index (RI) tomography for quantitative analysis of unstained DH82 cell line infected with Leishmania infantum. The cell RI is reconstructed by using a modality of optical diffraction tomography technique that employs partially coherent illumination, thus enabling inherent compatibility with conventional wide‐field microscopes. The experimental results demonstrate that the cell dry mass concentration (DMC) obtained from the RI allows for reliable detection and quantitative characterization of the infection and its temporal evolution. The RI provides important insight for studying morphological changes, particularly membrane blebbing linked to an apoptosis (cell death) process induced by the disease. Moreover, the results evidence that infected DH82 cells exhibit a higher DMC than healthy samples. These findings open up promising perspectives for clinical diagnosis of Leishmania.     

Announcement - Reference List

A (Ca²⁺, Mg²⁺)-ATPase activity and a (Ca²⁺, Mg²⁺)-dependent phosphorylation from ATP have been found in plasma membrane fragments from squid optical nerves under conditions where contamination by intracellular organelles is unlikely. The properties of this (Ca²⁺, Mg²⁺)-ATPase activity are almost identical to those of the ATP-dependent uncoupled Ca²⁺ efflux observed in dialyzed squid giant axons. This gives further support to the notion that the mechanism responsible for maintaining the low levels of ionized Ca concentration in nerves at rest is not a Na⁺-Ca²⁺ exchange system but an ATP-driven uncoupled Ca²⁺ pump.     

Luminescence properties of red‐emission Mg4Nb2O9:Eu3+ phosphor

Red‐emitting Mg₄Nb₂O₉:Eu³⁺ phosphor is synthesized via a solid‐state reaction method in air, and its crystal structure and luminescence are investigated. The phosphor can be excited efficiently by ~ 395 nm light, coupled well with a ~ 395 nm near‐ultraviolet chip and emits red light at ~ 613 nm with sharp spectra due to ⁵D₀ → ⁷ F₂ transition of the Eu³⁺ ion. Mg₄Nb₂O₉:Eu³⁺ phosphor sintered at 1350 ºC shows Commission international de I'Eclairage (CIE) chromaticity coordinates of x = 0.6354, y = 0.3592, and is a potential red‐emitting phosphor candidate for white light‐emitting diodes (W‐LEDs) under ~ 395 nm near‐ultraviolet LED chip excitation. Copyright © 2014 John Wiley & Sons, Ltd.     

高斯光束中细胞横向受力分析

按照几何光学的原理建立了高斯光束中细胞受力的力学模型,并利用数值计算,得到了细胞偏离光轴受到的向轴回复力大小与细胞的离轴距离X0、直径2R等的关系.结果表明高斯光束对大小不同的细胞有相同的光学势阱宽度,对较大细胞势阱较深所以较容易稳定俘获.讨论了光钳设计中注意的问题.     

采用OCT系统对组织光学通透的研究

组织通透方法采用高折射率化学试剂对生物组织进行渗透,改变组织的光学均匀性,可以有效地改善光学成像的穿透深度,受到生物医学光学研究领域的重视。利用光学相干层析成像技术,测量通透过程中不同测量深度下组织的散射特征的变化。通过采用系统信号对数的梯度值近似地表征光学散射系数,研究了通透过程中组织的散射特征随渗透时间和测量深度的动态关系。实验证明了组织通透可以有效地增加光子的穿透深度,并改善成像质量。研究发现:不同测量深度处组织的散射系数及其变化幅度、变化过程和变化趋势等均存在一定的差异性,并与组织的微观结构、其通透效果,化学试剂在组织中的渗透行为等有密切关系,有助于组织通透过程的理解,并为组织通透机制提供可能的实验依据。     

Quantitative Histology Using Confocal Microscopy: Implementation of Unbiased Stereology Procedures

Direct, two-dimensional counting or measuring of cells as they appear in histological sections is subject to a number of artifacts that can lead to erroneous conclusions about changes in cellular populations. Numerous correction procedures devised to compensate for these artifacts are collectively termed model-based stereology due to their reliance on a model of cell geometry for correction formulas. These corrections are valid only to the degree that the geometric model reflects cellular morphology. In addition, there are requirements for population homogeneity that are often not met in biological material. The development of design-based stereology provides a way to directly count or measure cells in three dimensions, avoiding errors (biases) and the need for assumptions regarding cell size, shape, and orientation to be validated. On this basis, these procedures are described as unbiased stereology. The recent commercial availability of semiautomated stereology systems has substantially reduced the effort and experimenter error (bias) associated with the use of design-based stereology. The optical resolution of confocal microscopy and the ability to collect registered series of focal planes is ideally suited for the three-dimensional sampling of design-based stereology. Unfortunately, stereological procedures are not available in any confocal microscope software and it is up to the user to implement these procedures. Strategies and illustrations of approaches to implementing stereological procedures on a confocal microscope are presented. Where possible, particular design issues are discussed and solutions suggested. With user requests, future generations of confocal software may integrate collection of confocal images with the implementation of design-based stereology.     

Application of polydimethylsiloxane-based optical system for measuring optical density of microbial culture

The performance of recently developed polydimethylsiloxane (PDMS)-based optical system was tested for measuring optical density of microbial culture. The data showed that PDMS-based spectrometer is superior to “one drop” spectrometers in the accuracy, and has an advantage over conventional spectrometers in measuring dense culture without dilution.     

Optical clearing methods: An overview of the techniques used for the imaging of 3D spheroids

Spheroids have emerged as in vitro models that reproduce in a great extent the architectural microenvironment found in human tissues. However, the imaging of 3D cell cultures is highly challenging due to its high thickness, which results in a light-scattering phenomenon that limits light penetration. Therefore, several optical clearing methods, widely used in the imaging of animal tissues, have been recently explored to render spheroids with enhanced transparency. These methods are aimed to homogenize the microtissue refractive index (RI) and can be grouped into four different categories, namely (a) simple immersion in an aqueous solution with high RI; (b) delipidation and dehydration followed by RI matching; (c) delipidation and hyperhydration followed by RI matching; and (d) hydrogel embedding followed by delipidation and RI matching. In this review, the main optical clearing methods, their mechanism of action, advantages, and disadvantages are described. Furthermore, the practical examples of the optical clearing methods application for the imaging of 3D spheroids are highlighted.     

General model for depth‐resolved estimation of the optical attenuation coefficients in optical coherence tomography

We present the proof of concept of a general model that uses the tissue sample transmittance as input to estimate the depth‐resolved attenuation coefficient of tissue samples using optical coherence tomography (OCT). This method allows us to obtain an image of tissue optical properties instead of intensity contrast, guiding diagnosis and tissues differentiation, extending its application from thick to thin samples. The performance of our method was simulated and tested with the assistance of a home built single‐layered and multilayered phantoms (~100 μm each layer) with known attenuation coefficient on the range of 0.9 to 2.32 mm^?1. It is shown that the estimated depth‐resolved attenuation coefficient recovers the reference values, measured by using an integrating sphere followed by the inverse adding doubling processing technique. That was corroborated for all situations when the correct transmittance value is used with an average difference of 7%. Finally, we applied the proposed method to estimate the depth‐resolved attenuation coefficient for a thin biological sample, demonstrating the ability of our method on real OCT images.     

Closed loop tracked Doppler optical coherence tomography based heart monitor for the Drosophila melanogaster larvae

This paper presents a novel instrument for biosciences, useful for studies of moving embryos. A dual sequential imaging/measurement channel is assembled via a closed‐loop tracking architecture. The dual channel system can operate in two regimes: (i) single‐point Doppler signal monitoring or (ii) fast 3‐D swept source OCT imaging. The system is demonstrated for characterizing cardiac dynamics in Drosophila melanogaster larva. Closed loop tracking enables long term in vivo monitoring of the larvae heart without anesthetic or physical restraint. Such an instrument can be used to measure subtle variations in the cardiac behavior otherwise obscured by the larvae movements.

A fruit fly larva (top) was continuously tracked for continuous remote monitoring. A heartbeat trace of freely moving larva (bottom) was obtained by a low coherence interferometry based doppler sensing technique.     

In vivo optoretinography of phototransduction activation and energy metabolism in retinal photoreceptors

The objective of this study is to verify the anatomic correlate of the second (2nd) outer retina band in optical coherence tomography (OCT), and to demonstrate the potential of using intrinsic optical signal (IOS) imaging for concurrent optoretinography (ORG) of phototransduction activation and energy metabolism in stimulus activated retinal photoreceptors. A custom-designed OCT was employed for depth-resolved IOS imaging in mouse retina activated by a visible light flicker stimulation. The spatiotemporal properties of the IOS changes at the photoreceptor outer segment (OS) and inner segment (IS) were quantitatively evaluated. Rapid IOS change was observed at the OS almost right away, and the IOS at the IS was relatively slow. Comparative analysis indicates that the OS-IOS reflects transient OS deformation caused by the phototransduction activation, and IS-IOS might reflect the energy metabolism caused by mitochondria activation in retinal photoreceptors. The consistency of the distribution of the IS-IOS and the 2nd OCT band supports the IS ellipsoid (ISe), which has abundant mitochondria, as the signal source of the 2nd OCT band of the outer retina.     

‘Go with the flow ’: A review of methods and advancements in blood flow imaging

Physics has delivered extraordinary developments in almost every facet of modern life. From the humble thermometer and stethoscope to X‐Ray, CT, MRI, ultrasound, PET and radiotherapy, our health has been transformed by these advances yielding both morphological and functional metrics. Recently high resolution label‐free imaging of the microcirculation at clinically relevant depths has become available in the research domain. In this paper, we present a comprehensive review on current imaging techniques, state‐of‐the‐art advancements and applications, and general perspectives on the prospects for these modalities in the clinical realm. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Capillary blood flow imaging within human finger cuticle using optical microangiography

We report non‐invasive 3D imaging of capillary blood flow within human finger cuticle by the use of Doppler optical microangiography (DOMAG) and ultra‐high sensitive optical microangiography (UHS‐OMAG) techniques. Wide velocity range DOMAG method is applied to provide red blood cell (RBC) axial velocity mapping in capillary loops with ranges of ±0.9 mm/s and ±0.3 mm/s. Additionally, UHS‐OMAG technique is engineered to acquire high resolution image of capillary morphology. The presented results are promising to facilitate clinical trials of treatment and diagnosis of various diseases such as diabetes, Raynaud's phenomenon, and connective tissue diseases by quantifying cutaneous blood flow changes within human finger cuticle. (© 2013 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)