随着医疗诊断需求的增加, 生物分子检测技术越来越受到人们的重视, 液相生物芯片技术作为一种高通量, 多通道的分子检测手段在近几年得到了飞速发展。 通过层层自组装方法制备以微片为载体的拉曼光谱编码液相生物芯片, 并利用自行搭建的一套高灵敏度、 高分辨率的光学系统, 实现对液相生物芯片的定性与定量分析。 光学系统由拉曼光谱检测系统与荧光显微成像系统耦合而成。 在拉曼光谱检测系统中激光器发射出785 nm波长的激光, 通过二向色镜, 带反反射镜与物镜汇聚到样品上, 样品产生的拉曼散射光, 经物镜, 带反反射镜, 二向色镜与拉曼滤波片, 最后通过凹透镜聚焦到光谱仪的狭缝上, 光谱仪色散实现在线阵CCD上拉曼光谱的获取。 荧光显微成像系统应用光学成像原理, 通过调节凹透镜与405 nm的激发光之间的距离, 使激发光通过物镜均匀的照射到样品之上, 样品激发出的荧光, 通过物镜, 带反反射镜, 二向色镜, 滤波片与相应的凹透镜, 最后成像到面阵CCD上。 改进传统便携式拉曼光谱检测系统光路并选用相应波段的带反反射镜与焦距20倍的物镜完成拉曼光谱检测系统与荧光显微成像系统的耦合。 为了减少两路系统之间的相互影响选用合适的二向色镜以及滤波片, 在提高耦合系统获取数据的准确性中有着重要的作用。 该系统通过对反应之后的液相生物芯片进行拉曼光谱检测, 以完成对每个编码玻片的定性识别, 即解码; 同时激发反应后液相生物芯片的荧光并采集荧光强度图, 根据每个解码玻片上的荧光强度值完成对目标检测物的定量分析。 区别于传统荧光编码液相生物芯片, 拉曼光谱编码具有稳定性更强, 光谱分辨率更高等优点。 该光学系统集拉曼光谱检测系统与荧光显微成像系统于一体, 解决了目前未有基于拉曼编码的液相生物芯片的检测系统的问题, 并且可同时对多种目标物进行识别和定量分析, 提升了实验结果的准确性。

We established a photoacoustic imaging (PAI) system that can provide variable gain at different depths. The PAI system consists of a pulsed laser with an optical parametric oscillator working at a 728 nmwavelength and an imaging-acquisition-and-processing unit with an ultrasound transducer. Avoltage-controlled attenuator was used to realize variable gain at different depths when acquiring PAI signals. The proof-of-concept imaging results for variable gain at different depths were achieved using specific phantoms. Both resolution and optical contrast obtained through the results of variable gain for a targeted depth range are better than those of constant gain for all depths. To further testify the function, we imaged the sagittal section of the body of in vivo nude mice. In addition, we imaged an absorption sample embedded in a chicken breast tissue, reaching a maximum imaging depth of ~4.6 cm. The results obtained using the proposed method showed better resolution and contrast than when using 50 dB gain for all depths. The depth range resolution was ~1 mm, and the maximum imaging depth of our system reached ~4.6 cm. Furthermore, blood vessels can be revealed and targeted depth range can be selected in nude mice imaging.

目的: 本文设计了一套光声成像(photoacoustic imaging,PAI)系统,由脉冲激光、阵列换能器、临床超声(ultrasound,US)主机、软件平台以及成像样品组成。系统的图像质量、最大成像深度等重要参数需通过实验进行确定。方法: 使用本系统对黑色头发丝横截面进行成像,比较、分析光声(photoacoustic,PA)信号幅值的半极大处全宽度以量化图像分辨率。此外,使用系统对特定的光吸收体和鸡胸肉组织进行成像,确定系统的成像深度。结果: 实验结果证明了PAI系统的实现,其PA图像的平均轴向和横向分辨率分别约为0.18 mm和1.44 mm,系统的最大成像深度达到4.6 cm。结论: 本PAI系统PA图像分辨率优于US主机获得的US图像分辨率,系统最大成像深度与其他国际研究组的系统成像深度的数量级一致。通过进一步优化与活体组织实验的开展,本PAI系统将有望实现临床成像诊断。

Background: Infrared laser stimulation has been proposed as an innovative method to elicit an auditory nerve response. Most studies have focused on using long-wavelength infrared (> 980 nm) pulsed lasers with high water absorption coe±cients. This paper sought to assess whether a shortwavelength laser (465 nm) with an absorption coe±cient as low as 10-3 cm-1 would activate the auditory nerve and studied its potential mechanism. Method: Optical compound action potentials (OCAPs) were recorded when synchronous trigger laser pulses stimulate the cochlea before and after deafening, varying the pulse durations (from 800 μs to 3600 μs) and the amount of radiant energy (from 18.05 mJ/cm2 to 107.91 mJ/cm2). A thermal infrared imager was applied to monitor the temperature change of the guinea pig cochlea. Results: The results showed that pulsed laser stimulation at 465nm could invoke OCAPs and had a similar waveform compared to the acoustical compound action potentials. The amplitude of OCAPs had a positive correlation with the increasing laser peak power, while the latency of OCAPs showed a negative correlation. The imager data showed that the temperature in the cochlea rose quickly by about 0.3C right after stimulating the cochlea and decreased quickly back to the initial temperature as the stimulation ended. Conclusions: This paper demonstrates that 465-nm laser stimulation can successfully induce OCAPs outside the cochlea, and that the amplitude and latency of the invoked OCAPs are highly affected by laser peak power. This paper proposes that a photothermal effect might be the main mechanism for the auditory nerve response induced by short-wavelength laser stimulation.