窄等离子体吸收谱线宽度的纳米金锥用于光声成像

无损光声成像技术结合了纯光学成像高选择特性和纯超声成像中深穿透特性的优点,克服了光散射限制,实现了对活体深层组织的高分辨、高对比度成像。该成像技术对内源物质例如脱氧血红蛋白、含氧血红蛋白、黑色素、脂质等进行成像,提供了活体生物组织结构和功能信息,已经在生物医学领域表现出巨大的应用前景。然而,很多与病理过程相关的特征分子的光吸收能力较弱,在活体环境中难以被光声成像系统所识别,从而限制了光声成像技术的应用范围。基于功能纳米探针的光声成像-光声分子成像极大拓展光声成像的应用范围,可以在活体层面对病理过程进行分子水平的定性和定量研究,将为实现目标疾病的早期诊断提供强大的技术支持。本文发展在近红外具有窄吸收线宽(半高宽仅为60 nm)的纳米金锥作为新型的光声探针。通过选择不同径长比的纳米金锥,可以任意调节纳米金锥的吸收峰。通过调谐激光器的波长,可实现对不同吸收峰纳米金锥的选择性激发。纳米金锥将有可能用于多光谱光声成像,实现对不同靶标的目标分子探测。     

基于直线电机的大视场快速光声显微成像系统

光声成像技术是近年来发展的一种新型的无损医学成像技术,它是以脉冲激光作为激发源,以检测的声信号为信息载体,通过相应的图像重建算法重建组织内部结构和功能信息的成像方法。该方法结合了光学成像和声学成像的特点,可提供深层组织高分辨率和高对比度的组织层析图像,在生物医学临床诊断以及在体成像领域具有广泛的应用前景。目前光声成像的扫描方式主要有基于步进电机扫描方式和基于振镜的扫描方式,本文针对目前步进电机扫描速度慢(10 mm×10 mm;0.001帧/s),振镜扫描范围小(1 mm2)的不足,发展了基于直线电机扫描的大视场快速光声显微成像系统。同一条扫描线过程中直线电机速度最高可达200 mm/s。该技术采用逐线采集光声信号的方式,比逐点采集光声信号的步进电机快800倍。该系统对10 mm×10 mm全场扫描的扫描速度为0.8帧/s。最大可扫描视场范围可以达到50 mm×50 mm。大视场快速光声显微成像系统的发展将为生物医学提供新的成像工具。     

在体光声成像检测损伤组织及体内异物

利用旋转扫描光声成像采集系统对脑损伤动物进行在体成像检测研究.对由金属物刺伤的脑内组织损伤和出血现象进行高分辨成像;光声成像成功定位小鼠颅骨内针刺损伤的位置和清晰展现组织损伤引致的颅内瘀血;成功利用光声成像观测到外损伤金属异物在颅内的形态结构及位置信息,分析了光声成像对金属异物定位检测和组织损伤出血分布的检测可行性,为提出新型的脑外伤检测技术作应用基础的研究.     

光声成像及其在生物医学中的应用

光声成像是一种新近迅速发展起来、基于生物组织内部光学吸收差异、以超声作媒介的无损生物光子成像方法,它结合了纯光学成像的高对比度特性和纯超声成像的高穿透深度特性的优点,以超声探测器探测光声波代替光学成像中的光子检测,从原理上避开了光学散射的影响,可以提供高对比度和高分辨率的组织影像,为研究生物组织的结构形态、生理特征、代谢功能、病理特征等提供了重要手段,在生物医学临床诊断以及在体组织结构和功能成像领域具有广泛的应用前景.对光声成像技术的机理、光声成像技术和方法、光声图像重建算法以及光声成像在生物医学上的应用情况作一个简单介绍,希望有助于推动我国在该领域的科研和开发应用工作的迅速发展.     

光声结构与功能成像技术研究进展

光声成像技术利用短脉冲激光激发产生光声信号,可重建出组织的光吸收分布图像,它结合了纯光学成像的高对比度和纯声学成像的高分辨率特性.光声成像技术不仅能够有效的刻画生物组织结构,还能够精确实现无损功能成像,为研究生物组织的形态结构,生理、病理特征,代谢功能等提供了全新手段.本文简要分析了光声信号产生的机理,总结报道了目前实验室几套典型的成像系统及其最新应用进展,指出光声成像作为一种新型的生物医学成像方法,可望引发生物医学影像领域的一次革新.     

基于光谱编码的血管内光声组分成像

光声成像突破了传统的光学成像和超声成像在生物组织成像领域的困境,该技术基于光声(Photoacoustic,PA)效应,脉冲激光激励下的生物组织产生超声信号,超声信号被接收后,通过反投影算法将其携带的时间信息和强度信息转化为能够反映生物组织吸收结构和分布的可视化图像。基于不同生物组织的光吸收差异,当激发光强度均匀且稳定时,光声成像反映的就是该物质对于该波长光的吸收特性。本文中,我们基于导管式的血管内光声断层扫描平台结合多波长激发的光声成像算法开发了基于光谱编码的血管内光声组分成像系统,实现了在离体血管斑块中脂质组分的定量成像,高分辨获得了脂质核心的大小形态和边界信息,表征了斑块内的脂质相对含量。     

一体化的光声-荧光显微镜用于活体肿瘤成像

报道了一种利用单一波长激发的同时产生光声和荧光信号的显微成像系统,本成像系统具有超高的成像分辨率(<6μm)。借助外源的造影剂在近红外的吸收特性,利用光声-荧光显微成像系统对活体肿瘤进行光声/荧光成像。实验结果表明,光声-荧光显微镜在早期肿瘤的成像和检测等方面具有潜在的应用价值。因此,通过研究和选择适当的双模态造影剂,该系统在不同病理模型中可以提供更准确的组织信息及生理参数。     

基于非线性热扩散效应的亚衍射极限光声二次谐波显微成像技术

本文提出了一种基于非线性热扩散效应的光声二次谐波显微SH-PAM成像技术,用于实现亚衍射极限光声成像。生物组织受到强度调制的高斯激光束辐射时,组织吸收光子形成高斯分布的温度场,由于热扩散系数非线性热效应引起的非线性光声PA效应,从而产生光声二次谐波信号。模拟和试验结果均表明,重建后的光声二次谐波成像的横向分辨率超过了传统光学成像分辨率。本文通过仿体样品验证了该方法的可行性,并且对人表层皮肤细胞进行了成像,以证明其对生物样品的成像能力。该方法扩展了传统光声成像的范围,为超分辨成像开辟了新的可能性,为生物医学成像和材料检测提供了新的方法。     

基于压缩感知理论的光声成像方法研究现状

光声成像是一种新兴的无损生物医学成像方法,因其兼具高灵敏的光学对比度和超声能够对深层组织进行高分辨成像的优点,已经成为当前生物医学成像领域发展最快的技术之一。光声成像的光吸收对比度能够反映生物组织微小的组织病变,与血氧饱和度等多种功能和生理信息紧密相关,目前已被证明在肿瘤血管新生研究、早期癌症检测和心血管疾病诊断等方面有很大的应用潜力。基于超声阵列探测的常规光声计算层析成像系统,数据采集量大,由此导致的较低数据采集和成像速度成为制约该技术临床应用和转化的重要因素。压缩感知理论可以在远低于Nyquist采样定理的欠采样方式下,高质量重建信号,已被广泛用于信号处理和传统的医学图像重建领域。自2009年压缩感知理论被应用于光声成像以来,已有的研究结果表明,该方法为解决目前大区域光声成像的数据采集和成像速度问题提供了一条有效的途径。本文将重点介绍压缩感知理论用于光声成像的基本原理、研究现状、面临的问题和应用前景。     

基于光声和LIBS双模态成像技术在生物医学中的发展现状及趋势

光声成像和激光诱导击穿光谱技术（LIBS）是近些年在成像领域发展非常迅速的两种技术,在医学影像学方面有着巨大的潜力。当激光照射到组织时,组织表面会同时产生光声信号和等离子体,光声信号携带着生物组织内光吸收的特征信息,等离子体特征光谱也可以示踪组织内的元素信息。本文总结了两种技术的研究背景和成像原理,然后,通过对光声成像和LIBS成像模式进行分析,进一步展现了两种技术结合的可能性,并介绍了它们在病理切片成像和组织金属元素示踪等领域的应用。最后,我们对两种技术结合的双模态成像系统进行了深入的探讨和展望,以期其在医学诊断和图像领域发挥重要作用。     

光动力学疗法剂量学的研究进展

随着光动力学疗法 ( photodynamic therapy,PDT ) 基础研究的不断深入和临床应用的广泛开展,如何精确量化光动力剂量,并根据患者的个体差异进行剂量的实时调整和优化已成为亟待解决的挑战性难题,属PDT研究的前沿热点．综述了现有PDT剂量学研究方法及其相应检测技术的研究进展,其中包括：a．测定光通量密度、光敏剂浓度和氧分压;b．测量光敏剂的光漂白速率和光致产物;c．监测PDT前后组织的光生物学响应;d．检测单态氧在1 270 nm的近红外发光．同时,还分析了这些PDT剂量学方法的优点和局限性．最后,讨论了PDT剂量学研究中所面临的挑战．     

基于CdSe-ZnS量子点的PDT体外灭活 HL60最佳实验参数的研究

随着光动力学疗法( photodynamic therapy,PDT)基础研究的不断深入和临床应用的广泛开展,根据患者的个体差异寻求高性能的光敏剂和精确量化光动力剂量,已成为亟待解决的难题,并日渐成为PDT研究的热点.以ZnS包裹的CdSe量子点(CdSe-ZnS)作为光敏剂,以人前髓细胞（早幼细胞）株HI6O为研究对...     

Cytotoxic Efficacy of Photodynamic Therapy in Osteosarcoma Cells In Vitro

In recent years, there has been the difficulty in finding more effective therapies against cancer with less systemic side effects. Therefore Photodynamic Therapy is a novel approach for a more tumor selective treatment.Photodynamic Therapy (PDT) that makes use of a nontoxic photosensitizer (PS), which, upon activation with light of a specific wavelength in the presence of oxygen, generates oxygen radicals that elicit a cytotoxic response¹. Despite its approval almost twenty years ago by the FDA, PDT is nowadays only used to treat a limited number of cancer types (skin, bladder) and nononcological diseases (psoriasis, actinic keratosis)².The major advantage of the use of PDT is the ability to perform a local treatment, which prevents systemic side effects. Moreover, it allows the treatment of tumors at delicate sites (e.g. around nerves or blood vessels). Here, an intraoperative application of PDT is considered in osteosarcoma (OS), a tumor of the bone, to target primary tumor satellites left behind in tumor surrounding tissue after surgical tumor resection. The treatment aims at decreasing the number of recurrences and at reducing the risk for (postoperative) metastasis.In the present study, we present in vitro PDT procedures to establish the optimal PDT settings for effective treatment of widely used OS cell lines that are used to reproduce the human disease in well established intratibial OS mouse models. The uptake of the PS mTHPC was examined with a spectrophotometer and phototoxicity was provoked with laser light excitation of mTHPC at 652 nm to induce cell death assessed with a WST-1 assay and by the counting of surviving cells. The established techniques enable us to define the optimal PDT settings for future studies in animal models. They are an easy and quick tool for the evaluation of the efficacy of PDT in vitro before an application in vivo.     

Synthesis and biological evaluation of glucose conjugated phthalocyanine as a second-generation photosensitizer

Photodynamic therapy (PDT) is a treatment method using light and photosensitizers (PSs), which is categorized as a non-invasive surgery treatment for cancers. When the tumor is exposed to a specific light, the PSs become active and generate reactive oxygen species (ROS), mainly singlet oxygen which kills nearby cancer cells. PDT is becoming more widely recognized as a valuable treatment option for localized cancers and pre-cancers of skin as it has no long-term effects on the patient. But, due to the limited penetration rate of light into the skin and other organs, PDT can’t be used to treat large cancer cells or cancer cells that have grown deeply into the skin or other organs. Hence, in this study, our focus centers on synthesizing glucose-conjugated phthalocyanine (Pc) compatible with near-infrared (NIR) irradiation as second-generation photosensitizer, so that PDT can be used in a wider range to treat cancers without obstacles.     

Involvement of both caspase-dependent and -independent pathways in apoptotic induction by hexaminolevulinate-mediated photodynamic therapy in human lymphoma cells

Photodynamic therapy (PDT) is a cancer treatment based on the interaction of a photosensitizer, light and oxygen. PDT with the endogenous photosensitizer, protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (ALA) or its derivatives is a modification of this treatment modality with successful application in dermatology. However, the mechanism of cell destruction by ALA-PDT has not been elucidated. In this study a human T-cell lymphoma Jurkat cell line was treated with PDT using hexaminolevulinate (HAL, hexylester of ALA). Four hours following treatment nearly 80% of the cells exhibited typical apoptotic features. Mitochondrial pro-apoptotic proteins were evaluated by Western blots in subcellular fractionated samples. PDT caused cytosolic translocation of cytochrome c and nuclear redistribution of apoptosis-inducing factor (AIF), but the release of mitochondrial Smac/DIABLO, Omi/HtrA2 and EndoG was not observed. The release of cytochrome c was followed by the cleavage of caspase-9 and caspase-3 as well as its downstream substrates, together with oligonucleosomal DNA fragmentation. The pan-caspases inhibitor, z-VAD.fmk, prevented oligonucleosomal DNA fragmentation, but failed to inhibit PDT-mediated apoptosis. The apoptotic induction by AIF-mediated caspase-independent pathway was also found after HAL-PDT with large-scale DNA fragmentation in the presence of z-VAD.fmk. These results demonstrate that cytochrome c-mediated caspase-dependent pathway and AIF-induced caspase-independent pathway are simultaneously involved in the apoptotic induction by PDT. When the cytochrome c-induced caspase-dependent pathway is blocked, the cells go into apoptosis via AIF-mediated pathway, clearly demonstrating that the cytochrome c-mediated caspase-dependent pathway is not required for such apoptotic induction. This finding may have an impact on improved PDT effectiveness.     

The role of oxygen monitoring during photodynamic therapy and its potential for treatment dosimetry.

Understanding of the biology of photodynamic therapy (PDT) has expanded tremendously over the past few years. However, in the clinical situation, it is still a challenge to match the extent of PDT effects to the extent of the disease process being treated. PDT requires drug, light and oxygen, any of which can be the limiting factor in determining efficacy at each point in a target organ. This article reviews techniques available for monitoring tissue oxygenation during PDT. Point measurements can be made using oxygen electrodes or luminescence-based optodes for direct measurements of tissue pO2, or using optical spectroscopy for measuring the oxygen saturation of haemoglobin. Imaging is considerably more complex, but may become feasible with techniques like BOLD MRI. Pre-clinical studies have shown dramatic changes in oxygenation during PDT, which vary with the photosensitizer used and the light delivery regimen. Better oxygenation throughout treatment is achieved if the light fluence rate is kept low as this reduces the rate of oxygen consumption. The relationship between tissue oxygenation and PDT effect is complex and remarkably few studies have directly correlated oxygenation changes during PDT with the final biological effect, although those that have confirm the value of maintaining good oxygenation. Real time monitoring to ensure adequate oxygenation at strategic points in target tissues during PDT is likely to be important, particularly in the image guided treatment of tumours of solid organs.     

Online electrochemical monitoring of nitric oxide during photodynamic therapy

Photodynamic therapy (PDT), as a novel treatment modality, is based on the use of a photosensitizing agent with an excitation light source for the treatment of various malignancies. Its effect is mediated through reactive oxygen species and nitric oxide (NO), which are shown to be present in apoptosis. Individual differences among patients and even in different areas of the same tumor in one patient may cause a major problem with PDT: dose calculation during application of the light. An electrochemical sensor is proposed for online monitoring of NO generation as a solution of this problem. 5-Aminolevulinic acid (ALA) was administered as the photosensitizer in rat cerebellum. An amperometric sensor, selective to NO, was designed and tested both in vitro and in vivo during PDT. ALA-mediated PDT resulted in rapid generation of NO, starting as early as the application of light on the tissue. Simultaneous amperometric recordings have been carried out for 5 min during PDT. The progressive increase in NO concentration peaked at 1.10 min and then the response current began to decrease until it reached a plateau at around 70% of its peak value. This study, for the first time, electrochemically demonstrates the generation of NO during PDT. Rapid and stable responses obtained by the experimental setup confirmed that this method could be used as an online monitoring system for PDT-mediated apoptosis.     

光动力疗法治疗感染性疾病的动物模型

光动力疗法(photodynamic therapy,PDT)是利用特定波长的激发光照射生物靶标上的光敏剂,从而产生活性氧并有效杀伤多种耐药病原体的新型治疗方式,具有作用广、安全可控、不易耐受等优点。大量体外实验已证实了PDT疗效,但目前动物实验数据较少,且治疗参数不一,一定程度上影响了PDT在临床治疗中的广泛应用。本文综述近年来PDT用于体内抗感染治疗的动物模型构建、治疗方案设计等方面的研究进展,为未来PDT抗感染研究及临床应用提供参考。     

藻红蛋白光敏剂研究进展

光动力学治疗法作为一种新的肿瘤治疗方法,近年来发展十分迅速。从红藻中提取的藻红蛋白可以作为光动力学治疗法的一种新的光敏剂。本概述了我国红藻藻红蛋白资源概况、光疗法和光敏剂作用机理及其研究发展历史与现状,重点阐述了藻红蛋白光敏剂的应用现状、前景和发展趋势,并认为藻红蛋白是光动力学治疗法中一种非常有前景的光敏剂。藻红蛋白在490nm有吸收光谱,而发射光谱位于560nm;藻红蛋白能特异性地聚集在肿瘤细胞周围,吸收周围环境光能并传递给氧分子,使氧分子转化为具有强氧化性的多线态氧,从而可以大量杀死肿瘤细胞。     

Antiangiogenic photodynamic therapy (PDT) by using long-circulating liposomes modified with peptide specific to angiogenic vessels

For the improvement of therapeutic efficacy in photodynamic therapy (PDT) by using a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA), we previously prepared polyethylene glycol (PEG)-modified liposomes encapsulating BPD-MA (PEG-Lip BPD-MA). PEGylation of liposomes enhanced the accumulation of BPD-MA in tumor tissue at 3 h after injection of it into Meth-A-sarcoma-bearing mice, but, unexpectedly, decreased the suitability of the drug for PDT when laser irradiation was performed at 3 h after the injection of the liposomal photosensitizer. To improve the bioavailability of PEG-Lip BPD-MA, we endowed the liposomes with active-targeting characteristics by using Ala-Pro-Arg-Pro-Gly (APRPG) pentapeptide, which had earlier been isolated as a peptide specific to angiogenic endothelial cells. APRPG-PEG-modified liposomal BPD-MA (APRPG-PEG-Lip BPD-MA) accumulated in tumor tissue similarly as PEG-Lip BPD-MA and to an approx. 4-fold higher degree than BPD-MA delivered with non-modified liposomes at 3 h after the injection of the drugs into tumor-bearing mice. On the contrary, unlike the treatment with PEG-Lip BPD-MA, APRPG-PEG-Lip BPD-MA treatment strongly suppressed tumor growth after laser irradiation at 3 h after injection. Finally, we observed vasculature damage in the dorsal air sac angiogenesis model by APRPG-PEG-Lip BPD-MA-mediated PDT. The present results suggest that antiangiogenic PDT is an efficient modality for tumor treatment and that tumor neovessel-targeted, long-circulating liposomes are a useful carrier for delivering photosensitizer to angiogenic endothelial cells.