# Proteomics in Forensic Analysis: Applications for Human Samples
###### Abstract  
Proteomics, the large-scale study of all proteins of an organism or system, is a powerful tool for studying biological systems. It can provide a holistic view of the physiological and biochemical states of given samples through identification and quantification of large numbers of peptides and proteins. In forensic science, proteomics can be used as a confirmatory and orthogonal technique for well-built genomic analyses. Proteomics is highly valuable in cases where nucleic acids are absent or degraded, such as hair and bone samples. It can be used to identify body fluids, ethnic group, gender, individual, and estimate post-mortem interval using bone, muscle, and decomposition fluid samples. Compared to genomic analysis, proteomics can provide a better global picture of a sample. It has been used in forensic science for a wide range of sample types and applications. In this review, we briefly introduce proteomic methods, including sample preparation techniques, data acquisition using liquid chromatography-tandem mass spectrometry, and data analysis using database search, spectral library search, and de novo sequencing. We also summarize recent applications in the past decade of proteomics in forensic science with a special focus on human samples, including hair, bone, body fluids, fingernail, muscle, brain, and fingermark, and address the challenges, considerations, and future developments of forensic proteomics. forensics; proteomics; biomarker; human identification; serology; hair; bone +
Footnote †: journal: Medical  
a holistic view of the physiological and biochemical states of given samples [2]. A proteome profile, including proteins and their abundances, provides a better global picture of a sample than static DNA information. In other words, proteomics can determine biological processes that are occurring [5]. While traditional gel-based proteomics is labor-intensive and time-consuming, the development of LC-MS/MS-based proteomics in the last two decades allows separation and analysis of thousands of peptides and proteins in several hours, which considerably increases the throughput of proteomics [6]. It also possesses some advantages as compared with the well-established immunoassays, such as higher specificity and repeatability, reduced time, labor, and long-term cost, the ability of multiplexing. Particularly, proteomics can avoid the requirement of genetically tagged proteins and specific antibodies for each protein [7]. In addition, the sample preparation workflow of proteomics can be automated using some liquid handling workstations, such as Agilent AssayMAP Bravo [8] and Biomek NXP Span-8 [9]. Most of the steps in bottom-up and top-down proteomics can be automated to increase precision, repeatability, and high-throughput performance [10]. In biological forensics, DNA is undoubtedly effective for human identification from various sample types, such as blood, skin, urine, and hair. However, in some cases, DNA might not answer all questions relating to forensics, such as the biological fluid or tissue type of a sample [4]. DNA in samples is sometimes unavailable or degraded, whereas proteins can persist and thus, can be analyzed instead [11]. Proteins themselves are also the targeted biomolecules when analyzing protein toxins, protein drugs, and hormones. Therefore, proteomics can be a confirmatory and orthogonal technique for well-built DNA sequencing, and an additional strategy to reveal other information [4]. Currently, forensic proteomics is in the early stages of development. An increasing number of studies have used proteomics in forensics, such as identification of tissue and body fluid [12; 13; 14], identification and quantification of protein toxins [15; 16], human individualization [17; 18], detection of protein drugs and hormones in sports [19; 20], and discrimination of wild strains and laboratory-adapted strains of bacteria [21; 22]. Several reviews and book chapters on forensic proteomics are available. Recently, [PERSON] et al.