Alkaline Phosphatase for Estimating the Time since Deposition of Blood Fingerprints by Scanning Electrochemical Microscopy,Analytical Chemistry

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Alkaline Phosphatase for Estimating the Time since Deposition of Blood Fingerprints by Scanning Electrochemical Microscopy
Analytical Chemistry ( IF 6.7 ) Pub Date : 2023-12-05 , DOI: 10.1021/acs.analchem.3c03692
Hongyu Chen ₁ , Lu Tian ₁ , Xiangyu Sun ₁ , Lu Liu ₁ , Rongliang Ma ₂ , Meiqin Zhang ₁

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Blood is one of the most frequent and valuable traces encountered at crime scenes, where knowing the time since deposition (TSD) of bloodstains tremendously assists forensic experts to screen out crime-related evidence and aids in the reconstruction of the event sequence. Although increasing proof-of-concept methodologies for investigating the TSD of bloodstains have been reported, there is still no accepted strategy in forensic practice as the aging mechanism involves complex components, leading to the inaccuracy of the estimation results. Herein, an endogenous biomarker of alkaline phosphatase (ALP) was chosen to investigate the TSD by scanning electrochemical microscopy (SECM). Results demonstrate that the ALP activity acquired via SECM lateral scan assay exhibited a clear decrease over time, and a similar trend was observed on both poly(vinylidene fluoride) (PVDF) membrane and glass, with the aging kinetics on PVDF membrane being faster than glass. By means of quantitatively calculating the flux of generated p-aminophenol (PAP), we established the aging curve and realized the TSD estimation of blood fingerprints (BFPs) that was unable to be distinguished via optical measurements. Intriguingly, the as-obtained estimation accuracy ranged from 74.6 to 93.7%, proving the possibility of using an ALP biomarker and SECM. More appealingly, the predicted TSDs were capable of accurately differentiating the deposition sequence of overlapping BFPs, which was hardly achieved by optical means. Therefore, this proof-of-concept strategy demonstrates the value of SECM as a forensic tool and opens possibilities for revealing multidimensional information about crime.

中文翻译：

碱性磷酸酶用于通过扫描电化学显微镜估算血液指纹沉积后的时间

血液是犯罪现场最常见、最有价值的痕迹之一，了解血迹沉积时间 (TSD) 可以极大地帮助法医专家筛查与犯罪相关的证据，并有助于重建事件序列。尽管已有越来越多的研究血迹 TSD 的概念验证方法被报道，但由于老化机制涉及复杂的成分，导致估计结果不准确，在法医学实践中仍然没有公认的策略。在此，选择碱性磷酸酶 (ALP) 的内源性生物标志物通过扫描电化学显微镜 (SECM) 研究 TSD。结果表明，通过SECM横向扫描测定获得的ALP活性随着时间的推移表现出明显的下降，并且在聚偏二氟乙烯（PVDF）膜和玻璃上观察到类似的趋势，其中PVDF膜的老化动力学比玻璃更快。通过定量计算生成的对氨基苯酚（PAP）的通量，建立了老化曲线，实现了光学测量无法区分的血液指纹（BFP）的TSD估计。有趣的是，所获得的估计准确度范围为 74.6% 至 93.7%，证明了使用 ALP 生物标志物和 SECM 的可能性。更吸引人的是，预测的 TSD 能够准确区分重叠 BFP 的沉积顺序，这是光学手段很难实现的。因此，这种概念验证策略证明了 SECM 作为取证工具的价值，并为揭示有关犯罪的多维信息提供了可能性。

更新日期：2023-12-05

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