Towards Fingermark Dating: A Raman Spectroscopy Proof-of-Concept Study

Dhvar5- and MSI78-coated titanium are bactericidal against methicillin-resistant Staphylococcus aureus, immunomodulatory and osteogenic

Infection is one of the major issues associated with the failure of orthopedic devices, mainly due to implant bacterial colonization, biofilm formation, and associated antibiotic resistance. Antimicrobial peptides (AMP) are a promising alternative to conventional antibiotics given their broad-spectrum of activity, low propensity to induce bacterial resistance, and ability to modulate host immune responses. Dhvar5 (LLLFLLKKRKKRKY) and MSI78 (GIGKFLKKAKKFGKAFVKILKK) are two AMP with broad-spectrum activity against bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), one of the most problematic etiologic agents in Orthopedic Devices-Related Infections (ODRI). This work aims to evaluate the bactericidal, immunomodulatory and osteogenic potential of Dhvar5- and MSI78-coated titanium surfaces (AMP-Ti). Two AMP-Ti surfaces were successfully obtained by grafting Dhvar5 (0.8 ± 0.1 µM/mm2) or MSI78 (0.5 ± 0.3 µM/mm2) onto titanium substrates through a polydopamine layer. Both AMP-Ti were bactericidal against MRSA, eradicating bacteria upon contact for 6 h in a culture medium supplemented with human plasma proteins. The AMP-Ti immunomodulatory potential was evaluated using human primary macrophages, by assessing surfaces capacity to induce pro-/anti-inflammatory (M1/M2) markers and cytokines. While in naïve conditions both AMP-Ti surfaces slightly promoted the M2 marker CD163, in response to LPS and IFN-γ (simulating a bacterial infection), both AMP increased the M1 marker CCR7 and enhanced macrophage secretion of pro-inflammatory IL-6 and TNF-α cytokines, particularly for Ti-MSI78 surfaces. Additionally, both AMP-Ti surfaces were cytocompatible and promoted osteoblastic cell differentiation. This proof-of-concept study demonstrated the high potential of Dhvar5- and MSI78-Ti as antimicrobial coatings for ODRI prevention. STATEMENT OF SIGNIFICANCE: This study investigates the bactericidal effects of the antimicrobial peptides Dhvar5 and MSI78, immobilized on titanium (Ti) surfaces through a polydopamine coating, aiming at the prevention of Orthopedic-Device Related Infections (ODRIs). The developed coatings displayed MRSA-sterilizing activity, while revealing an immunomodulatory potential towards macrophages and promoting osteoblastic cell differentiation. This strategy allows a quick and easy immobilization of high quantities of AMP, unlike most other approaches, thus favoring its clinical translation.

Short communications: Exploring temporal fluorescent changes in the composition of human semen stains

Semen traces are considered important pieces of evidence in forensic investigations, especially those involving sexsual offenses. Recently, our research group developed a fluorescence-based technique to accurately determine the age of semen traces. However, the specific compounds resonsible for the fluoresescent behaviour of ageing semens remain unknown. As such, in this exploratory study, the aim is to identify the components associated with the fluorescent behavior of ageing semen traces. In this investigation semen stains and various biofluorophores commonly found in body fluids were left to aged for 0, 2, 4, 7, 14 and 21 days. Subsequently, thin-layer chromatography (TLC) and ultra-performance liquid chromatography (UPLC) mass spectrometry were performed to identify the biofluorophores present in semen. Several contributors to the autofluorescence could be identified in semen stain, these include tryptophan, kynurenine, kynurenic acid, and norharman. The study sheds light on the.

Predicting Fingerprint Age Based on Ozonolysis Kinetics of Unsaturated Triacylglycerol Degradation

Answering the question, "How old is a fingerprint?", is a highly sought-after aim in forensic science. Despite several decades of studies to find an empirical correlation in fingerprint aging, there has been no reliable method so far. In this study, we attempt to determine the time since deposition (TSD) of aged fingerprints from the chemical profile captured within a matrix-assisted laser desorption/ionization mass spectrometry data set. Our approach is based on the chemical kinetics associated with the ambient ozonolysis of unsaturated triacylglycerols (TGs), a major component in fingerprint lipids. First, ozone concentration and ambient temperature were determined to be the major factors in the degradation of unsaturated TGs. A simple kinetics model is then developed to describe the decay of unsaturated TGs, dictated only by the temperature and ozone concentration. This model is then applied to the degradation of TGs in a mixture of TG standards and multiple individuals' fingerprints. The overall decay of unsaturated TGs follows the pseudo-first-order reaction kinetics, validating our hypothesis; however, there are significant person-to-person variations in the initial abundance of unsaturated TGs and the decay rate, hampering the accurate prediction of TSD unless they are corrected for each individual. Nevertheless, the model's applicability for ambient fingerprint aging data was successfully demonstrated.

Characterization of the Striatal Extracellular Matrix in a Mouse Model of Parkinson's Disease

Parkinson’s disease’s etiology is unknown, although evidence suggests the involvement of oxidative modifications of intracellular components in disease pathobiology. Despite the known involvement of the extracellular matrix in physiology and disease, the influence of oxidative stress on the matrix has been neglected. The chemical modifications that might accumulate in matrix components due to their long half-live and the low amount of extracellular antioxidants could also contribute to the disease and explain ineffective cellular therapies. The enriched striatal extracellular matrix from a mouse model of Parkinson’s disease was characterized by Raman spectroscopy. We found a matrix fingerprint of increased oxalate content and oxidative modifications. To uncover the effects of these changes on brain cells, we morphologically characterized the primary microglia used to repopulate this matrix and further quantified the effects on cellular mechanical stress by an intracellular fluorescence resonance energy transfer (FRET)-mechanosensor using the U-2 OS cell line. Our data suggest changes in microglia survival and morphology, and a decrease in cytoskeletal tension in response to the modified matrix from both hemispheres of 6-hydroxydopamine (6-OHDA)-lesioned animals. Collectively, these data suggest that the extracellular matrix is modified, and underscore the need for its thorough investigation, which may reveal new ways to improve therapies or may even reveal new therapies.

Determination of Time since Deposition of Fingerprints via Colorimetric Assays

Past investigations involving fingerprints have revolved heavily around the image of the fingerprint-including the minutiae, scarring, and other distinguishing features-to visually find a match to its originator. Recently, it has been proven that the biochemical composition can be used to determine originator attributes, such as sex, via chemical and enzymatic cascades. While this provides pertinent information about the originator's identity, it is not the only piece of information that can be provided. This research was designed with three goals in mind: (1) identify how long it would take before an aged female fingerprint could no longer be differentiated from a male fingerprint, (2) identify a correlation between the data collected and a specific time since deposition (TSD) time point, and (3) identify if a specific amino acid could be contributing to the decreasing response seen for the aging fingerprints. Using ultraviolet-visible (UV-vis) spectroscopy, aged fingerprints were evaluated over the course of 12 weeks via three chemical assays previously used for fingerprint analysis-the ninhydrin assay, the Bradford assay, and the Sakaguchi assay. As fingerprints age, the conditions they are exposed to cause the biochemical composition to decompose. As this occurs, there is less available to be detected by analytical means. This results in a less intense color production and, thus, a lower measured absorbance. The results displayed here afforded the ability to conclude that all three goals set forth for this research were accomplished-a female fingerprint can be differentiated from a male fingerprint for at least 12 weeks, UV-vis data collected from aged fingerprints can be correlated to a TSD range but not necessarily a specific time point, and the decomposition of at least a single amino acid can afford the ability to estimate the TSD of the fingerprint.

Advances in fingermark age determination techniques

Fingermarks have long been recognized as one of the most reliable and valuable evidence for personal identification. In practice, fingerprint analysis primarily concentrates on latent fingerprint visualization. However, fingerprint visualization techniques do not always enable individualization when fingermarks collected in crime scenes are fragmentary, ambiguous, or deformed. Age determination techniques based on physical and chemical composition changes in fingerprints over time have attracted researchers' attention in recent years. Nevertheless, the components of fingerprints are liable to factors including donor features, deposition conditions, substrate properties, environmental conditions and revealing methods. All the influences mainly contribute to unreliable outcomes of age estimation. Recent developments in fingermark age determination have moved forward to more precise approaches. The advanced methods can be classified into two categories including techniques based on the modifications of physical characteristics and chemical composition characteristics. Herein, the review includes the five types of variables that influence the aging process. The methodologies are subsequently highlighted along with their advantages and disadvantages. Furthermore, photography, optical, microscopy and electrochemical methods, and vibrational spectroscopy and mass spectrometry (MS) techniques are summarized in detail, with an emphasis on their utilization.

Changes in latent fingermark glyceride composition as a function of sample age using UPLC-IMS-QToF-MSE

The composition of fingermark residue has been an important topic in forensic science, mainly in efforts to better understand and eventually improve the efficacy of latent fingermark detection methods. While the lipid fraction has been extensively studied, there is currently little information about how the glyceride fraction of latent fingermarks is chemically altered over time following deposition. A previously reported untargeted ultra performance liquid chromatography-ion mobility spectrometry-quadrupole time-of-flight mass spectrometry (UPLC-IMS-QToF-MS^E) method was used to investigate changes over time in fingermark di- and triglycerides. Charged latent fingermark samples from 5 donors were analysed up to 28 days following deposition. Significant changes in glyceride composition occurred with increased sample age, attributed primarily to the oxidation of unsaturated triglycerides through ozonolysis. Considerably fewer unsaturated TGs were identified in samples 7 and 28 days following deposition, while mono- and diozonides of these lipids were identified as major components of aged samples. Additional compounds were identified as possible aldehyde and carboxylic acid derivatives resulting from the reaction of water with ozonolysis intermediates. While the onset of these processes occurred rapidly following deposition, continuing oxidation over time was seen via the progressive ozonolysis of diunsaturated triglycerides. These results represent a further step towards understanding the factors affecting fingermark composition, ageing and subsequent detection under operational conditions.

Interpol review of fingermarks and other body impressions 2016-2019

This review paper covers the forensic-relevant literature in fingerprint and bodily impression sciences from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20 Review%20 Papers%202019. pdf.

Methodologies Applied to Fingerprint Analysis

This systematic review deals with the last 10 years of research in analytical methodologies for the analysis of fingerprints, regarding their chemical and biological constituents. A total of 123 manuscripts, which fit the search criteria defined using the descriptor "latent fingermarks analysis," were selected. Its main instrumental areas (mass spectrometry, spectroscopy, and innovative methods) were analyzed and summarized in a specific table, highlighting its main analytical parameters. The results show that most studies in this field use mass spectrometry to identify the constituents of fingerprints, both to determine the chemical profile and for aging. There is also a marked use of mass spectrometry coupled with chromatographic methods, and it provides accurate results for a fatty acid profile. Additional significant results are achieved by spectroscopic methods, mainly Raman and infrared. It is noteworthy that spectroscopic methods using microscopy assist in the accuracy of the analyzed region of the fingerprint, contributing to more robust results. There was also a significant increase in studies using methods focused on finding new developers or identifying components present in fingerprints by rapid tests. This systematic review of analytical techniques applied to the detection of fingerprints explores different approaches to contribute to future studies in forensic identification, verifying new demands in the forensic sciences and assisting in the selection of studies for the progress of research.

Towards Fingermark Dating: A Raman Spectroscopy Proof-of-Concept Study

Fingermarks have, for a long time, been vital in the forensic community for the identification of individuals, and a possibility to non‐destructively date the fingermarks would of course be beneficial. Raman spectroscopy is, herein, evaluated for the purpose of estimating the age of fingermarks deposits. Well‐resolved spectra were non‐destructively acquired to reveal spectral uniqueness, resembling those of epidermis, and several molecular markers were identified that showed different decay kinetics: carotenoids > squalene > unsaturated fatty acids > proteins. The degradation rates were accelerated, less pronounced for proteins, when samples were stored under ambient light conditions, likely owing to photo‐oxidation. It is hypothesized that fibrous proteins are present and that oxidation of amino acid side chains can be observed both through Raman and fluorescence spectroscopy. Clearly, Raman spectroscopy is a useful technique to non‐destructively study the aging processes of fingermarks.