中国激光, 2021, 48(3): 0307002, 网络出版: 2021-03-01

基于荧光光谱法的皮肤胆固醇快速无创检测技术

Rapid Non-Invasive Technology for Skin Cholesterol Detection Based on Fluorescent Spectrometry
作者单位

1安徽师范大学物理与电子信息学院, 安徽 芜湖 241000

2中国科学院合肥物质科学研究院安徽光学精密机械研究所, 安徽省医用光学诊疗技术与装备工程实验室, 安徽 合肥 230026

3中国科学技术大学附属第一医院健康管理中心, 安徽 合肥 230001

4皖江新兴产业技术发展中心, 安徽省生物医学光学仪器工程技术研究中心, 安徽 铜陵 244000

摘要
皮肤胆固醇含量可以作为评价动脉粥样硬化的重要指标之一,现有的皮肤胆固醇含量检测主要基于实验室活检进行,缺少快速无创的检测技术和装备。针对以皮肤胆固醇含量为评价指标的动脉粥样硬化的早期快速筛查需求,本文提出了基于荧光光谱法的皮肤胆固醇快速无创检测方法,研发了一种皮肤胆固醇无创检测系统。为了提高测量的准确性和稳定性,该系统对温度引起的检测试剂荧光效率的波动进行了修正。本文结合气相色谱法对测量结果的准确性进行了验证,并通过检测正常人群和动脉粥样硬化高风险人群的皮肤胆固醇含量,明确了该系统的临床应用价值。本文的研究结果表明,462~520 nm波段内的平均荧光强度与温度的相关系数为-0.995(p<0.0001),可据此建立温度校准曲线对由温度差异引起的荧光波动进行修正。校正后,系统测量的皮肤胆固醇含量与气相色谱测量值的相关性显著,相关系数为0.905(p<0.0001)。在动脉粥样硬化高风险人群的筛查实验中,动脉粥样硬化高风险人群和正常人群的皮肤胆固醇检测结果具有显著差异(P=0.0004)。与现有技术相比,基于荧光光谱法的皮肤胆固醇检测技术具有测量快速无创等优势,为大规模开展动脉粥样硬化的早期风险筛查提供了先进技术手段。
Abstract

Objective Skin cholesterol is an important biomarker for early atherosclerosis screening. Atherosclerosis is the leading cause of disability and death from cardiovascular disease. Effective control of pathogenic factors in the early pathological stage may delay or prevent the development of asymptomatic atherosclerosis into cardiovascular diseases. Thus, skin cholesterol detection becomes relevant in the prevention of cardiovascular diseases. Traditional skin cholesterol detection methods, such as skin biopsy or tape stripping, are invasive and usually time consuming. Alternatively, the recent three-drop method is being widely studied. In this method, three specific concentrations of reagents that bind to skin cholesterol are used on the skin surface of a subject, and atherosclerosis can be diagnosed by analyzing the reagent color changes. However, the three-drop method is sensitive to the application habits of the operator. Moreover, the detection reagents contain enzymes, polymers, and small molecule compounds, hindering quality control and increasing the sensitivity to environmental factors such as temperature and pH levels. We report a non-invasive skin cholesterol detection technique based on fluorescent spectrometry. By measuring the fluorescence spectrum of fluorescent-labeled skin, the cholesterol content can be calculated from the fluorescence spectra. This method corrects the influence of temperature on the test results and provides stability under various environmental conditions. Moreover, the skin cholesterol content can be obtained within 4 minutes. The proposed method provides a rapid non-invasive and stable method for skin cholesterol detection and corresponding applications including early atherosclerosis screening.

Methods The proposed non-invasive skin cholesterol detection system is composed of a light source, fiber probe, spectrometer, photodiode, infrared temperature sensor, and computer. The fluorescence fluctuation of the detection reagent caused by temperature variation is corrected by establishing the relation between temperature and the fluorescence intensity of the detection reagent. To confirm the accuracy of the proposed skin cholesterol detection system, we extract skin cholesterol with absolute ethanol after the non-invasive measurement. The cholesterol content in the extraction liquid is determined by gas chromatography, and the correlation between the two results are analyzed. Finally, the clinical applicability of the proposed system is confirmed by measuring skin cholesterol content from both healthy subjects and subjects with high risk of presenting atherosclerosis.

Results and Discussions The schematic of the proposed non-invasive skin cholesterol detection system based on fluorescent spectrometry is shown in Fig. 1. The system accurately detects skin cholesterol content after correcting for temperature. The average fluorescence intensity of the detection reagent in the 462--520 nm wavelength band decreases with increasing temperature, resulting in a significant negative correlation between fluorescence intensity and temperature (r=-0.995, p<0.0001). This relation can be used to establish a calibration curve to correct for temperature (Fig. 5). We recruited 80 subjects to verify the accuracy of the proposed system. The skin cholesterol content measured using the proposed temperature-corrected system is highly correlated (correlation coefficient of 0.905) with that measured using gas chromatography (Fig. 6). These results verify the accuracy of the proposed system to measure skin cholesterol. To verify whether the proposed system can distinguish healthy subjects from subjects with high risk of presenting atherosclerosis, we used the system in 43 and 46 subjects from the respective groups. There is a significant difference in skin cholesterol content between the healthy and high risk samples (p=0.0004) (Fig. 7). The proposed non-invasive skin cholesterol detection system can screen subjects with high risk of presenting atherosclerosis. Nevertheless, clinical trials are required for verification given the small sample size used in this study.

Conclusions We propose a rapid non-invasive detection system for skin cholesterol based on fluorescent spectrometry. The system quickly provides the skin cholesterol content on-site from the fluorescence spectrum of detection reagents that specifically bind to skin cholesterol. The proposed system performs temperature correction to prevent deviations of the measurement results and improve accuracy and stability. The system and its detection accuracy are verified through comparisons with skin cholesterol results obtained from gas chromatography. The proposed system may be used to screen people with high risk of presenting atherosclerosis by detecting skin cholesterol content in healthy subjects and subjects at high risk. Overall, the proposed system can detect skin cholesterol accurately, non-invasively, and quickly. We expect that the widespread adoption of this technology will contribute to the prevention and control of cardiovascular diseases.

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