The ability to perform direct rapid analysis in air and at atmospheric pressure is a remarkable attraction of laser-induced breakdown spectroscopy (LIBS) for the diagnostic quantification of disease biomarker metals in body tissue. However, accurate trace analysis is limited by matrix effects and a pronounced background that masks the subtle (peak-free) analyte signals because tissue plasma is dense and most lines are optically thick. In this work, a peak-free chemometric LIBS method based on a single-shot (for rapidity and nondestructiveness) and an artificial neural network multivariate calibration strategy with spectral feature selection was evaluated for its utility for direct trace quantitative analysis of copper (Cu), iron (Fe), manganese (Mg), magnesium (Mg), and zinc (Zn) in model soft body tissue. The spectral signatures corresponding to the biometals (so-called because the metals are intrinsic to tissue biochemistry) were generated by spiking their known human-body-representative concentrations in molten paraffin wax. The developed multivariate analytical model achieved ≥95% accuracy as determined from the analysis of oyster tissue-certified reference material. The analytical models were tested on the liver, breast, and abdominal tissue biopsies. The results of applying the model to the clinical tissues indicated the absence or presence (including severity) of cancer as either malignant or benign, in agreement with the pathological examination report.

中文翻译：

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通过组织中的痕量金属生物标志物直接快速检测癌症的无峰化学计量激光诱导击穿光谱方法的评估

在空气和大气压下进行直接快速分析的能力是激光诱导击穿光谱 (LIBS) 对身体组织中疾病生物标志物金属的诊断量化的显着吸引力。然而，准确的痕量分析受到基质效应和显着背景的限制，该背景掩盖了细微的（无峰）分析物信号，因为组织血浆是致密的，并且大多数线在光学上很厚。在这项工作中，评估了基于单次（快速和无损）和具有光谱特征选择的人工神经网络多元校准策略的无峰化学计量 LIBS 方法在铜 (Cu) 直接痕量定量分析中的实用性、模型软体组织中的铁 (Fe)、锰 (Mg)、镁 (Mg) 和锌 (Zn)。与生物金属相对应的光谱特征（所谓的因为金属是组织生物化学所固有的）是通过在熔融石蜡中添加已知的人体代表浓度来产生的。根据牡蛎组织认证的参考材料的分析确定，开发的多变量分析模型的准确度≥95%。分析模型在肝脏、乳房和腹部组织活检上进行了测试。将该模型应用于临床组织的结果表明癌症的不存在或存在（包括严重程度）为恶性或良性，与病理检查报告一致。根据牡蛎组织认证的参考材料的分析确定，开发的多变量分析模型的准确度≥95%。分析模型在肝脏、乳房和腹部组织活检上进行了测试。将该模型应用于临床组织的结果表明癌症的不存在或存在（包括严重程度）为恶性或良性，与病理检查报告一致。根据牡蛎组织认证的参考材料的分析确定，开发的多变量分析模型的准确度≥95%。分析模型在肝脏、乳房和腹部组织活检上进行了测试。将该模型应用于临床组织的结果表明癌症的不存在或存在（包括严重程度）为恶性或良性，与病理检查报告一致。