A blue spectral shift of the hemoglobin soret band correlates with the age (time since deposition) of dried bloodstains

Determination of time since deposition of bloodstains through NIR and UV-Vis spectroscopy - A critical comparison

Time elapsed since bloodstain deposition is a crucial aspect in forensic investigations, where non-destructive spectroscopic methods play a pivotal role. While extensive research has been conducted by UV-Vis spectroscopy, showcasing its utility in specific cases, there is still a paucity of studies based on NIR spectroscopy, which has the potential to overcome the limitations of the UV-Vis-based methods. To compensate for this disequilibrium, the present study aimed to evaluate the NIR applicability for estimating the age of forensic bloodstains and develop a performance comparison with UV-Vis spectroscopy methods. Capillary blood was sampled and subjected to a 16-day aging, during which it was repeatedly analyzed using both spectroscopic methods. Subsequently, chemometric analysis was applied to process the spectral data and independently assess the methods' performance. Classical preprocessing transforms (i.e., Savitzky-Golay derivatives and SNV transform) were used together with more targeted strategies, such as class centering, whose benefit was highlighted by PCA. Lastly, PLS regression models were computed to evaluate the effectiveness of both spectroscopic methods in estimating the time elapsed since blood trace deposition. Comparable root mean square errors in prediction (RMSEP) - 40 and 55 h for UV-Vis and NIR spectroscopy, respectively - were observed for both techniques, featuring an improvement with respect to the existing literature for NIR spectroscopy. Data fusion strategies for a multi-instrumental platform were also explored, evaluating advantages and disadvantages of low-level and mid-level approaches. The results indicated that NIR spectroscopy integrated with adequate chemometric strategies deserves increased appreciation in forensic bloodstain dating.

Raman Spectroscopy for the Time since Deposition Estimation of a Menstrual Bloodstain

Forensic chemistry plays a crucial role in aiding law enforcement investigations by applying analytical techniques for the analysis of evidence. While bloodstains are frequently encountered at crime scenes, distinguishing between peripheral and menstrual bloodstains presents a challenge. This is due to their similar appearance post-drying. Raman spectroscopy has emerged as a promising technique capable of discriminating between the two types of bloodstains, offering invaluable probative information. Moreover, estimating the time since deposition (TSD) of bloodstains aids in crime scene reconstruction and prioritizing what evidence to collect. Despite extensive research focusing on TSD estimations, primarily in peripheral bloodstains, a crucial gap exists in determining the TSD of menstrual bloodstains. This study demonstrates how Raman spectroscopy effectively analyzes biological samples like menstrual blood, showing similar aging patterns to those of peripheral blood and provides proof-of-concept models for determining the TSD of menstrual blood. While this work shows promising results for creating a universal model for bloodstain age determination, further testing with more donors needs to be conducted before the implementation of this method into forensic practice.

Development of novel polymer haemoglobin based particles as an antioxidant, antibacterial and an oxygen carrier agents

This innovative work aims to develop highly biocompatible and degradable nanoparticles by encapsulating haemoglobin (Hb) within poly-ε-caprolactone for novel biomedical applications. We used a modified double emulsion solvent evaporation method to fabricate the particles. A Scanning electron microscope (SEM) characterized them for surface morphology. Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-visible spectroscopies (UV-visible) elucidated preserved chemical and biological structure of encapsulated haemoglobin. The airproof equilibrium apparatus obtained the oxygen-carrying capacity and P50 values. The DPPH assay assessed free radical scavenging potential. The antibacterial properties were observed using four different bacterial strains by disk diffusion method. The MTT assay investigates the cytotoxic effects on mouse fibroblast cultured cell lines (L-929). The MTT assay showed that nanoparticles have no toxicity over large concentrations. The well-preserved structure of Hb within particles, no toxicity, high oxygen affinity, P50 value, and IC50 values open the area of new research, which may be used as artificial oxygen carriers, antioxidant, and antibacterial agents, potential therapeutic agents as well as drug carrier particles to treat the cancerous cells. The novelty of this work is the antioxidant and antibacterial properties of developed nanoparticles are not been reported yet. Results showed that the prepared particles have strong antioxidant and antibacterial potential.

Transcriptomic changes and prediction of time since deposition of blood stains

In forensics, it is important to determine the time since deposition (TSD) of bloodstains, one of the most common types of biological evidence in criminal cases. However, no effective TSD inference methods have been established despite extensive attempts in forensic science. Our study investigated the changes in the blood transcriptome over time, and we found that degradation could be divided into four stages (days 0-2, 4-14, 21-56, and 84-168) at 4 °C. A random forest prediction model based on these transcriptional changes was trained on experimental samples and tested in separate test samples. This model was able to successfully predict TSD (area under the curve [AUC] = 0.995, precision = 1, and recall = 1). Thus, this proof-of-concept pilot study has practical significance for assessing physical evidence. Meanwhile, 11 upregulated and 13 downregulated transcripts were identified as potential time-marker transcripts, laying a foundation for further development of TSD analysis methods in forensic science and crime scene investigation.

Understanding protein-nanoparticle interactions leading to protein corona formation: In vitro - in vivo correlation study

Nanoparticles (NPs) in contact with biological fluids form a biomolecular corona through interactions with proteins, lipids, and sugars, acquiring new physicochemical properties. This work explores the interaction between selected proteins (hemoglobin and fetuin-A) that may alter NP circulation time and NPs of different surface charges (neutral, positive, and negative). The interaction with key proteins albumin and transferrin, the two of the most abundant proteins in plasma was also studied. Binding affinity was investigated using quartz crystal microbalance and fluorescence quenching, while circular dichroism assessed potential conformational changes. The data obtained from in vitro experiments were compared to in vivo protein corona data. The results indicate that electrostatic interactions primarily drive protein-NP interactions, and higher binding affinity does not necessarily translate into more significant structural changes. In vitro and single protein-NP studies provide valuable insights that can be correlated with in vivo observations, opening exciting possibilities for future protein corona studies.

Forensic analysis of biological fluid stains on substrates by spectroscopic approaches and chemometrics: A review

BACKGROUND

Bodily fluid stains are one of the most relevant evidence that can be found at the crime scene as it provides a wealth of information to the investigators. They help to report on the individuals involved in the crime, to check alibis, or to determine the type of crime that has been committed. They appear as stains in different types of substrates, some of them porous, which can interfere in the analysis. The spectroscopy techniques combined with chemometrics are showing increasing potential for their use in the analysis of such samples due to them being fast, sensitive, and non-destructive.

FINDINGS

This is a comprehensive review of the studies that used different spectroscopic techniques followed by chemometrics for analysing biological fluid stains on several surfaces, and under various conditions. It focuses on the bodily fluid stains and the most suitable spectroscopic techniques to study forensic scientific problems such as the substrate's characteristics, the influence of ambient conditions, the aging process of the bodily fluids, the presence of animal bodily fluids and non-biological fluids (interfering substances), and the bodily fluid mixtures. The most widely used techniques were Raman spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR). Nonetheless, other non-destructive techniques have been also used, like near infrared hyperspectral imaging (HSI-NIR) or surface enhanced Raman spectroscopy (SERS), among others. This work provides the criteria for the selection of the most promising non-destructive techniques for the effective in situ detection of biological fluid stains at crime scene investigations.

SIGNIFICANCE AND NOVELTY

The use of the proper spectroscopic and chemometric approaches on the crime scene is expected to improve the support of forensic sciences to criminal investigations. Evidence may be analysed in a non-destructive manner and kept intact for further analysis. They will also speed up forensic investigations by allowing the selection of relevant samples from occupational ones.

Contribution of the gasotransmitter nitric oxide to the structural and functional organization of erythrocytes under conditions of hypoxia/reoxygenation

Hypoxia is accompanied by changes in metabolism and cell functioning. Erythrocyte hemoglobin can be involved in adaptation to hypoxia by acting as an oxygen sensor, providing a link between oxygen content and blood circulation. The mechanisms providing this function have not been completely established. The purpose of this study was to evaluate the effect of the gasotransmitter nitric oxide on the structural and functional organization of erythrocytes under conditions of hypoxia/reoxygenation. NO participated in adaptive reactions under hypoxia/reoxygenation conditions by changing hemoglobin conformation, followed by changes in hemoprotein spectral characteristics and hemoglobin affinity to oxygen together with increasing anisocytosis, volume and cell surface. The increase in intracellular NO concentrations under hypoxic conditions was provided by extracellular fluid nitrites. Molsidomine (a NO donor) induced a higher NO increase without involvement of the nitrite reductase mechanism, it caused an increase in the average erythrocyte volume, anisocytosis, and an increase in the cell surface.

Nucleic Acids Persistence-Benefits and Limitations in Forensic Genetics

The analysis of genetic material may be the only way to identify an unknown person or solve a criminal case. Often, the conditions in which the genetic material was found determine the choice of the analytical method. Hence, it is extremely important to understand the influence of various factors, both external and internal, on genetic material. The review presents information on DNA and RNA persistence, depending on the chemical and physical factors affecting the genetic material integrity. One of the factors taken into account is the time elapsing to genetic material recovery. Temperature can both preserve the genetic material or lead to its rapid degradation. Radiation, aquatic environments, and various types of chemical and physical factors also affect the genetic material quality. The substances used during the forensic process, i.e., for biological trace visualization or maceration, are also discussed. Proper analysis of genetic material degradation can help determine the post-mortem interval (PMI) or time since deposition (TsD), which may play a key role in criminal cases.

Interactions of ultrashort laser pulses with hemoglobin: Photophysical aspects and potential applications

Hemoglobin (Hb), a life-sustaining and highly abundant erythrocyte protein, is not readily fluorescent. A few studies have already reported Two-Photon Excited Fluorescence (TPEF) of Hb, however, the mechanisms through which Hb becomes fluorescent upon interaction with ultrashort laser pulses are not completely understood. Here, we characterized photophysically this interaction on Hb thin film and erythrocytes using fluorescence spectroscopy upon single-photon/two-photon absorption, and UV-VIS single-photon absorption spectroscopy. A gradual increase of the fluorescence intensity, ending up with saturation, is observed upon prolonged exposure of Hb thin layer and erythrocytes to ultrashort laser pulses at 730 nm. When compared to protoporphyrin IX (PpIX) and oxidized Hb by H₂O₂, TPEF spectra from a thin Hb film and erythrocytes showed good mutual agreement, broad peaking at 550 nm, supporting hemoglobin undergoes degradation and that same fluorescent specie(s) originating from the heme moiety are generated. The uniform square shaped patterns of the fluorescent photoproduct exhibited the same level of the fluorescence intensity even after 12 weeks from the formation, indicating high photoproduct stability. We finally demonstrated the full potential of the formed Hb photoproduct with TPEF scanning microscopy towards spatiotemporally controlled micropatterning in HTF and single human erythrocyte labelling and tracking in the whole blood.

Effect of environmental conditions on bloodstain metabolite analysis

Establishing a correlation between environmental variables and chemical change can significantly improve the quality of research in multiple fields. Among various environmental variables, temperature and humidity are closely related to the rate of chemical reactions. This study aimed to confirm changes in metabolite markers that were previously discovered in other temperature and humidity environment conditions and to confirm the possibility that they could act as markers. After blood collection from the subjects and bloodstain preparation, the quantitative values of the bloodstain metabolites were confirmed (when the age of the bloodstain was within a month) under eight environmental conditions (4 °C/30%, 4 °C/60%, 25 °C/30%, 25 °C/60%, 25 °C/90%, 40 °C/30%, 40 °C/60%, and 40 °C/90%). Age-of-bloodstain estimation models were constructed to confirm the applicability of bloodstain metabolites as markers for bloodstain age in various environments. The average concentration of metabolite markers exhibited a decreasing trend with the age of the bloodstain, which transformed into an increasing trend from day 7 onwards. In terms of temperature and humidity, 25 °C and 90%, respectively, showed the most dissimilar metabolite change pattern compared to other conditions. The age-of-bloodstain estimation models developed here have an R-square value of up to 0.92 for each condition and an R-square value of 0.71 when all environmental conditions were combined. The findings herein highlight the immense potential of blood metabolites for field application, confirming the possibility of predicting metabolite changes from the rates of their chemical reactions and validating the importance of metabolites as age-of-bloodstain markers under various environmental conditions.

A microfluidic finger-actuated blood lysate preparation device enabled by rapid acoustofluidic mixing

For many blood-based diagnostic tests, including prophylactic drug analysis and malaria assays, red blood cells must be lysed effectively prior to their use in an analytical workflow. We report on a finger-actuated blood lysate preparation device, which utilises a previously reported acoustofluidic micromixer module. The integrated device includes a range of innovations from a sample interface, to the integration of blisters on a laser engraved surface and a large volume (130 μL) one-stroke manual pump which could be useful in other low-cost microfluidic-based point-of-care devices. The adaptability of the acoustic mixer is demonstrated on highly viscous fluids, including whole blood, with up to 65% percent volume fraction of red blood cells. Used in conjunction with a lysis buffer, the micromixer unit is also shown to lyse a finger-prick (approximately 20 μL) blood sample in 30 seconds and benchmarked across ten donor samples. Finally, we demonstrate the ease of use of the fully integrated device. Cheap, modular, but reliable, finger-actuated microfluidic functions could open up opportunities for the development of diagnostics with minimal resources.

The estimation of bloodstain age utilizing circRNAs and mRNAs biomarkers

Determining the time since deposition (TsD) of bloodstains can provide forensic investigators with additional clues, as it can corroborate eyewitness accounts, limit the number of suspects, and help confirm alibis. Bloodstains are the most common bodily fluid stains at crime scenes. In this study, we examined the relative expression levels (REs) of circRNAs and mRNAs data in bloodstains over ten time points by Real-time quantitative polymerase chain reaction (qPCR), to determine the utility of the relative expression levels of RNA markers for TsD estimation. Forensic samples more than just appear in indoor settings, we also evaluated the use of RNA degradation rate to indicate the age of bloodstains in different environments including indoor and outdoor conditions. The expression levels of six blood-specific mRNA markers (GYPA, CD93, ALAS2, SPTB, HBB, HBA), three highly expressed circRNAs in human peripheral blood (hsa_circ_0001445, hsa_circ_0000972, hsa_circ_0000095) and three reference genes (18 S, ACTB and U6) were analyzed across numerous ageing time points. Analysis of the degradation rates of individual RNAs under indoor and outdoor conditions showed that they exhibited a unique degradation profile during the four-month storage interval, with both circRNAs and mRNAs linearly showing continuous degradation, while U6 is more stable than other reference gene markers. In the current study, we firstly used circRNAs as additional novel biomarkers for bloodstain age estimation, and at the same time proved that different environments had a significant impact on the REs of certain blood biomarkers, and sex differences did not affect the age estimation of bloodstains. The REs of the selected RNA molecules in this study showed a non-linear relationship with bloodstain age and the mathematical formula for estimating the bloodstain age based on the relative expression levels of hsa_circ_0001445, ALAS2 and HBB can be used to estimate the TsD of bloodstains from the REs of bloodstains of unknown age, which represent a potentially effective approach to looking for time-dependent changes and TsD estimation.

Estimating the time since deposition (TsD) in saliva stains using temporal changes in microbial markers

Determining the time since deposition (TsD) of traces could be helpful in the investigation of criminal offenses. However, there are no reliable markers and models available for the inference of short-term TsD. The goal of this study was to investigate the potential of the succession pattern of human salivary microbial communities to serve as an efficiency TsD prediction tool in the resolution of the forensic cases. Saliva stains exposed to indoor conditions up to 20 days were collected and analyzed by 16S rRNA profiling using high-throughput sequencing technique. Noticeable differences in microbial composition were observed between different time points, and the indoor exposure time of saliva stains were inversely correlated with alpha diversity estimates across the measured time period. The sequencing results were used to identify TsD-dependent bacterial indicators to regress a generalized random forest model, resulting in a mean absolute deviation (MAD) of 1.41 days. Furthermore, a simplified TsD predictive model was also developed utilizing Enhydrobacter, Paenisporosarcina, and Janthinobacterium by quantitative PCR (qPCR) with a MAD of 1.32 days, and then forensic practice assessment were also performed by using mock samples with a MAD of 3.53 days. In conclusion, this study revealed significant changes in salivary microbial abundance as the prolongation of TsD. It demonstrated that the microbial biomarkers could be invoked as a "clock" for TsD estimation in human dried saliva stains.

Using total RNA quality metrics for time since deposition estimates in degrading bloodstains

The physicochemical changes occurring in biomolecules in degrading bloodstains can be used to approximate the time since deposition (TSD) of bloodstains. This would provide forensic scientists with critical information regarding the timeline of the events involving bloodshed. Our study aims to quantify the timewise degradation trends and temperature dependence found in total RNA from bloodstains without the use of amplification, expanding the scope of the RNA TSD research which has traditionally targeted mRNA and miRNA. Bovine blood with ACD-A anticoagulant was deposited and stored in plastic microcentrifuge tubes at 21 or 4°C and tested over different timepoints spanning 1 week. Total RNA was extracted from each sample and analyzed using automated high sensitivity gel electrophoresis. Nine RNA metrics were visually assessed and quantified using linear and mixed models. The RNA Integrity Number equivalent (RINe) and DV200 were not influenced by the addition of anticoagulant and demonstrated strong negative trends over time. The RINe model fit was high (R²  = 0.60), and while including the biological replicate as a random effect increased the fit for all RNA metrics, no significant differences were found between biological replicates stored at the same temperature for the RINe and DV200. This suggests that these standardized metrics can be directly compared between scenarios and individuals, with DV200 having an inflection point at approximately 28 h. This study provides a novel approach for blood TSD research, revealing metrics that are not affected by inter-individual variation, and improving our understanding of the rapid RNA degradation occurring in bloodstains.

Unlocking the potential of forensic traces: Analytical approaches to generate investigative leads

Forensic investigation involves gathering the information necessary to understand the criminal events as well as linking objects or individuals to an item, location or other individual(s) for investigative purposes. For years techniques such as presumptive chemical tests, DNA profiling or fingermark analysis have been of great value to this process. However, these techniques have their limitations, whether it is a lack of confidence in the results obtained due to cross-reactivity, subjectivity and low sensitivity; or because they are dependent on holding reference samples in a pre-existing database. There is currently a need to devise new ways to gather as much information as possible from a single trace, particularly from biological traces commonly encountered in forensic casework. This review outlines the most recent advancements in the forensic analysis of biological fluids, fingermarks and hair. Special emphasis is placed on analytical methods that can expand the information obtained from the trace beyond what is achieved in the usual practices. Special attention is paid to those methods that accurately determine the nature of the sample, as well as how long it has been at the crime scene, along with individualising information regarding the donor source of the trace.

Mitochondria are specifically vulnerable to 420nm light in drosophila which undermines their function and is associated with reduced fly mobility

Increased blue light exposure has become a matter of concern as it has a range of detrimental effects, but the mechanisms remain unclear. Mitochondria absorb short wavelength light but have a specific absorbance at 420nm at the lower end of the human visual range. This 420nm absorption is probably due to the presence of porphyrin. We examine the impact of 420nm exposure on drosophila melanogaster mitochondria and its impact on fly mobility. Daily 15 mins exposures for a week significantly reduced mitochondrial complex activities and increased mitochondrial inner membrane permeability, which is a key metric of mitochondrial health. Adenosine triphosphate (ATP) levels were not significantly reduced and mobility was unchanged. There are multiple options for energy/time exposure combinations, but we then applied single 420nm exposure of 3h to increase the probability of an effect on ATP and mobility, and both were significantly reduced. ATP and mitochondrial membrane permeability recovered and over corrected at 72h post exposure. However, despite this, normal mobility did not return. Hence, the effect of short wavelengths on mitochondrial function is to reduce complex activity and increasing membrane permeability, but light exposure to reduce ATP and to translate into reduced mobility needs to be sustained.

Post deposition aging of bloodstains probed by steady-state fluorescence spectroscopy

Blood is one of the most common body fluids discovered at crime scenes involving violent actions. It is one of the most important types of forensic evidence since it allows for the identification of the individual providing that there is a match with a known DNA profile. Determining the time since deposition (TSD) can assist investigators in establishing when the crime occurred or if a bloodstain present is actually related to the investigated event. To develop a forensically sound method for determining the TSD of a bloodstain, it is necessary to understand the underlying biochemical mechanisms occurring during aging. As biochemical processes occurring in blood are necessary for the continued survival of living organisms, they are important subjects of human biology and biomedicine and are well understood. However, the biochemistry of bloodstain aging ex vivo is primarily of interest to forensic scientists and has not yet been thoroughly researched. This preliminary study utilizes steady-state fluorescence spectroscopy to probe the changes in fluorescence properties of peripheral and menstrual blood up to 24-h post deposition. Peripheral and menstrual blood exhibited similar kinetic changes over time, assigned to the presence of the fluorophores: tryptophan, nicotinamide adenine dinucleotide (NADH), and flavins in both biological fluids. The biochemical mechanism of blood aging ex vivo is discussed.

Analysis of the influence of EDTA-treated reference samples on forensic bloodstain age estimation

The age estimation of blood traces provides important leads for the chronological assessment of criminal events and their reconstruction. To determine bloodstain age, experimental comparative data from a laboratory environment are used. Under these conditions the utilization of anticoagulants such as EDTA helps to suppress the blood clotting mechanism to allow the examination over a longer time period. This unnatural prevention of blood coagulation is highly questionable when estimating bloodstain age, since the blood's physical and chemical properties are altered. For this reason, the authors determined actual influence of EDTA on blood spectra over time in order to formulate a statement as to whether this effect can be measured. Human and porcine blood samples were aged under controlled conditions. The resulting UV/VIS spectra were separated into their individual components using signal separation techniques, allowing the changes in the ratios of the individual hemoglobin derivatives to be observed over time. The results show a significant influence of EDTA on the conversion of oxyhemoglobin to methemoglobin and a minor influence on the conversion of methemoglobin to hemichrome within the relevant time range of 5-100 h. The use of EDTA thus slows down the aging process of blood spots. To illustrate the great influence of EDTA, spectra of untreated pig blood samples were included as comparison data. These show that the difference between EDTA-treated and untreated blood samples is as great as the difference between human blood and pig blood. As a consequence of our findings experimental comparative data for the age estimation of bloodstains should never result from EDTA-treated blood.

Degradation of human mRNA transcripts over time as an indicator of the time since deposition (TsD) in biological crime scene traces

Knowledge about the age of a stain, also termed as time since deposition (TsD), would provide law-enforcing authorities with valuable information for the prosecution of criminal offenses. Yet, there is no reliable method for the inference / assessment of TsD available. The aim of this study was to gain further insight into the RNA degradation pattern of forensically relevant body fluids and to find candidate markers for TsD estimation. Blood, menstrual blood, saliva, semen and vaginal secretion samples were exposed to indoor (dark, room temperature) and outdoor (exposed to sun, wind, etc. but protected from rain) conditions for up to 1.5 years. Based on expression and degradation analyses, we were able to identify body fluid specific signatures and RNA degradation patterns. The indoor samples showed a marked drop in RNA integrity after 6 months, while the outdoor samples were difficult to interpret and therefore excluded for some of the analyses. Up to 4 weeks, indoor samples showed more stable and less degrading transcripts than outdoor samples. Stable transcripts tended to be significantly shorter than degrading ones or transcripts, which are neither degrading nor stable. We reinforced the body fluid specific and the housekeeping gene nature of previously reported markers. With an unbiased approach, we selected stable and degrading genes for each body fluid in the short term and assessed their integrity during extended storage. We identified several stable and degrading gene transcripts, which could be tested in a targeted assay to assess the TsD interval e.g. by analyzing the ratio of degrading vs stable transcripts. In conclusion, we were able to detect RNA degradation patterns in samples being aged up to 1.5 years and identified several candidate markers, which could be evaluated for TsD estimation.

Hyperspectral Imaging for Bloodstain Identification

Blood is key evidence to reconstruct crime scenes in forensic sciences. Blood identification can help to confirm a suspect, and for that reason, several chemical methods are used to reconstruct the crime scene however, these methods can affect subsequent DNA analysis. Therefore, this study presents a non-destructive method for bloodstain identification using Hyperspectral Imaging (HSI, 397-1000 nm range). The proposed method is based on the visualization of heme-components bands in the 500-700 nm spectral range. For experimental and validation purposes, a total of 225 blood (different donors) and non-blood (protein-based ketchup, rust acrylic paint, red acrylic paint, brown acrylic paint, red nail polish, rust nail polish, fake blood, and red ink) samples (HSI cubes, each cube is of size 1000 × 512 × 224, in which 1000 × 512 are the spatial dimensions and 224 spectral bands) were deposited on three substrates (white cotton fabric, white tile, and PVC wall sheet). The samples are imaged for up to three days to include aging. Savitzky Golay filtering has been used to highlight the subtle bands of all samples, particularly the aged ones. Based on the derivative spectrum, important spectral bands were selected to train five different classifiers (SVM, ANN, KNN, Random Forest, and Decision Tree). The comparative analysis reveals that the proposed method outperformed several state-of-the-art methods.

Forensic transcriptome analysis using massively parallel sequencing

The application of transcriptome analyses in forensic genetics has experienced tremendous growth and development in the past decade. The earliest studies and main applications were body fluid and tissue identification, using targeted RNA transcripts and a reverse transcription endpoint PCR method. A number of markers have been identified for the forensically most relevant body fluids and tissues and the method has been successfully used in casework. The introduction of Massively Parallel Sequencing (MPS) opened up new perspectives and opportunities to advance the field. Contrary to genomic DNA where two copies of an autosomal DNA segment are present in a cell, abundant RNA species are expressed in high copy numbers. Even whole transcriptome sequencing (RNA-Seq) of forensically relevant body fluids and of postmortem material was shown to be possible. This review gives an overview on forensic transcriptome analyses and applications. The methods cover whole transcriptome as well as targeted MPS approaches. High resolution forensic transcriptome analyses using MPS are being applied to body fluid/ tissue identification, determination of the age of stains and the age of the donor, the estimation of the post-mortem interval and to post mortem death investigations.

The fibrinolytic system enables the onset of Plasmodium infection in the mosquito vector and the mammalian host

Plasmodium parasites must migrate across proteinaceous matrices to infect the mosquito and vertebrate hosts. Plasmin, a mammalian serine protease, degrades extracellular matrix proteins allowing cell migration through tissues. We report that Plasmodium gametes recruit human plasminogen to their surface where it is processed into plasmin by corecruited plasminogen activators. Inhibition of plasminogen activation arrests parasite development early during sexual reproduction, before ookinete formation. We show that increased fibrinogen and fibrin in the blood bolus, which are natural substrates of plasmin, inversely correlate with parasite infectivity of the mosquito. Furthermore, we show that sporozoites, the parasite form transmitted by the mosquito to humans, also bind plasminogen and plasminogen activators on their surface, where plasminogen is activated into plasmin. Surface-bound plasmin promotes sporozoite transmission by facilitating parasite migration across the extracellular matrices of the dermis and of the liver. The fibrinolytic system is a potential target to hamper Plasmodium transmission.

Combined total internal reflection AF spectral-imaging and Raman spectroscopy for fast assessment of surgical margins during breast cancer surgery

The standard treatment for breast cancer is surgical removal mainly through breast-conserving surgery (BCS). We developed a new technique based on auto-fluorescence (AF) spectral imaging and Raman spectroscopy for fast intraoperative assessment of excision margins in BCS. A new wide-field AF imaging unit based on total internal reflection (TIR) was combined with a Raman spectroscopy microscope equipped with a 785 nm laser. The wavelength of the AF excitation was optimized to 365 nm in order to maximize the discrimination of adipose tissue. This approach allows for the non-adipose regions of tissue, which are at a higher risk of containing a tumor, to be targeted more efficiently by the Raman spectroscopy measurements. The integrated TIR-AF-Raman was tested on small tissue samples as well as fresh wide local excisions, delivering the analysis of the entire cruciate surface of BCS specimens (5.1 × 7.6 cm²) in less than 45 minutes and also providing information regarding the location of the tumor in the specimen. Full automation of the instrument and selection of a faster translation stage would allow for the measurement of BCS specimens within an intraoperative time scale (20 minutes). This study demonstrates that the TIR-AF Raman microscope represents a feasible step towards the development of a technique for intraoperative assessment of large WLE within intraoperative timescales.

Insight into the Biological Activity of Hennosides-Glucosides Isolated from Lawsonia inermis (henna): Could They Be Regarded as Active Constituents Instead

Henna is the current name of the dye prepared from the dry leaf powder of Lawsonia inermis (Lythraceae). Several studies have focused on the chemistry and pharmacology of the henna dyeing active compound, lawsone, obtained from the main constituents of leaves, hennosides, during the processing of plant material. However, knowledge regarding the biological activity of hennosides is largely lacking. In this paper, the redox activity of three hennoside isomers is reported. The pro-oxidative activity was confirmed by their ability to induce mild lysis of erythrocytes and to increase the level of methemoglobin at the concentration ≥ 500 μg/mL. The antioxidant activity of hennosides (concentration ≥100 μg/mL) was determined by FRAP and ABTS assays. At concentration of 500 μg/mL, antioxidant activity of hennoside isomers was equivalent to 0.46 ± 0.08, 0.62 ± 0.28 and 0.35 ± 0.03 mM FeSO4 × 7H2O, and 0.15 ± 0.01, 0.30 ± 0.01 and 0.09 ± 0.01 mM Trolox. Hennosides at 100 μg/mL concentration did not influence viability of human breast cancer cell lines MDA231 and MCF-7 and primary human peripheral blood and periodontal ligament-mesenchymal stem cells, but produced a modest increase in concentration of antioxidants in the cell culture supernatants. The evidenced antioxidant and pro-oxidant activities indicate their potential to act as redox balance regulator, which opens up the possibility of using hennosides in commercial phytomedicines.

In-vitro interaction of cerium oxide nanoparticles with hemoglobin, insulin, and dsDNA at 310.15 K: Physicochemical, spectroscopic and in-silico study

Lanthanide nanoparticles and nanorods especially their biocompatible oxide forms like cerium oxide nanoparticles (CNPs) with therapeutic applications are used to cure neurological oxidative stresses. Thus it tempts to study their biocompatible aspects by interactions with several biologically significant molecules. In-Vitro interactions of 15-240 μM CNPs with water, Phosphate buffered saline (PBS), DMEM media, Insulin (Ins) hemoglobin (Hb) and ds-DNA at 37 °C were studied. Their physicochemical properties study by Borosil Mansingh Survismeter (BMS) showed the first order interaction with the protein-protein structure breaking behaviour of CNPs with Hb, Ins, and DNA. Zeta potential measurements of CNPs in different biological medium show a net increase in negative charge magnitude with good colloidal stability. K_b = 4 × 106 mM^-1 of CNPs-DNA infer noncovalent interactions. Circular dichroism and FTIR revealed a loss of secondary conformation with increasing CNPs concentration. In-silico molecular docking depicts CNP interaction via conventional hydrogen bonding, carbon hydrogen bonding and electrostatic interactions at the minor groove of DNA. The study reports in-dept unfolding functional mechanism investigated by physicochemical, spectroscopic, and In-Silico approaches of protein on interactions with CNPs for safer-by-design use in medicine and pharmaceutics. Fundamentally the CeO₂ in ~62% and Ce₂O₃ in ~38% with Ce⁴⁺ and Ce³⁺ oxidation potentials develop a unique case of electronic configurations with 4f⁰5d⁰6s⁰ and 4f¹5d⁰6s⁰ electrons respectively which these studies a novel one.

UV-Visible spectroscopic effect on Haemoglobin & DNA degradation: A forensic approach

In forensic casework, sample degradation is a largely an unsolved problem that exists due to poor preservation protocols. In Indian subcontinent, the forensic blood stains are commonly exposed to different ecological conditions for months before they are collected and transferred to the forensic laboratory for analysis. Under such conditions, the question of haemoglobin (Hb) & nucleic acid stability is of utmost importance. The biological evidence, especially the blood sample that underwent extreme conditions should further be retained in an appropriate storage facility until processed for the forensic serology/DNA testing. The present study provides the spectroscopic approach of analyzing Hb and DNA degradation of forensic blood samples preserved under varied conditions (tabulated and graphically). These samples were further subjected to and DNA analysis to assess the quality of sample based on different preservation conditions. At last, this study suggests the effective and appropriate preservation protocol of sample soon after its collection.

Physicochemical interaction of cerium oxide nanoparticles with simulated biofluids, hemoglobin, insulin, and ds-DNA at 310.15 K

Interaction study in cerium oxide nanoparticles with biofluids and biomolecules via physicochemical, spectroscopic and in silico analytical approaches, showing conformational change.

Impacts of low concentration surfactant on red blood cell dielectrophoretic responses

Cell dielectrophoretic responses have been extensively studied for biomarker expression, blood typing, sepsis, circulating tumor cell separations, and others. Surfactants are often added to the analytical buffer in electrokinetic cellular microfluidic systems to lower surface/interfacial tensions. In nonelectrokinetic systems, surfactants influence cell size, shape, and agglomeration; this has not been systematically documented in electrokinetic systems. In the present work, the impacts of the Triton X-100 surfactant on human red blood cells (RBCs) were explored via ultraviolet-visible spectroscopy (UV-Vis) and dielectrophoresis (DEP) to compare nonelectrokinetic and electrokinetic responses, respectively. The UV-Vis spectra of Triton X-100 treated RBCs were dramatically different from that of native RBCs. DEP responses of RBCs were compared to RBCs treated with low concentrations of Triton X-100 (0.07-0.17 mM) to ascertain surfactant effects on dielectric properties. A star-shaped electrode design was used to quantify RBC dielectric properties by fitting a single-shell oblate cell model to experimentally-derived DEP spectra. The presence of 0.07 and 0.11 mM of Triton X-100 shifted the RBC's DEP spectra yielding lower crossover frequencies ( f C O ) . The single-shell oblate model revealed that cell radius and membrane permittivity are the dominant influencers of DEP spectral shifts. The trends observed were similar for 0.11 mM and 0.07 mM Triton X-100 treated cells. However, a further increase of Triton X-100 to 0.17 mM caused cells to only exhibit negative DEP. The magnitude of the DEP force increased with Triton X-100 concentration. This work indicates that dynamic surfactant interactions with cell membranes alter cell dielectric responses and properties.

Peroxide-Induced Liberation of Iron from Heme Switches Catalysis during Luminol Reaction and Causes Loss of Light and Heterodyning of Luminescence Kinetics

The peroxidation of luminol yields bright luminescence when the reaction is catalyzed by heme proteins. However, an excess of peroxide leads to less light and altered luminescence kinetics, an effect commonly referred to as "suicide inactivation". The aim of this study is to present the molecular processes causing this effect. A comprehensive set of data reported here demonstrates that suicide inactivation is due to a peroxide-induced liberation of iron from its coordinating porphyrin. Liberated iron launches catalysis of the reaction at much lower efficiency. The light-yielding efficiencies of different organic and inorganic catalysts are precisely quantified and compared. It is shown that the catalysis by free iron involves superoxide. This is explained by the formation of a ferryl-oxo-iron complex. In this context, a complete reaction mechanism involving a modified Fenton-Haber-Weiss cycle is proposed for the first time. The switch from the highly efficient biogenically catalyzed luminescence to a less efficient inorganically catalyzed reaction is accompanied by a transition from "flash-type" to "glow-type" luminescence kinetics. Ethylenediaminetetraacetic acid-mediated chelation of iron is used to demonstrate this effect and to separate both kinetics. The explanation of kinetic heterodyning is underpinned by mathematical modeling. The results are able to explain the as yet unexplained phenomena discussed in the less recent literature and to settle disputes about them. It is concluded that peroxide concentrations exceeding the level tolerated by the catalyzing heme protein negatively impact performance and precision of luminol-based assays, where the light yield is used as a quantitative measure for analyte concentrations.

Internal standard metabolites for obtaining absolute quantitative information on the components of bloodstains by standardization of samples

Analysis of the components of bloodstains found at crime scenes can provide important information for solving the crime. However, components of blood and bloodstains vary with volume and various other unpredictable factors. Therefore, it is necessary to specify the volume of the initial liquid blood droplet and standardize the analysis. In this study, internal standard metabolites that remained constant in a certain amount of bloodstain, long after deposition of the stain, were identified. Liquid chromatography-electrospray ionization-tandem mass spectrometry of the metabolites extracted from the bloodstain samples at various time points (0, 7, 14, 21, and 28 days) was performed. The coefficient of variation (CV) of the obtained molecular features was calculated for each criterion: time point, subject, and all data (time and subject, triplicate of each). Five molecular features with average CVs of less than or equal to 5% were selected as candidates. Partial least squares discriminant analysis and principal component analysis showed that the effect on the candidates was very low over time. The fold-change value of abundances was confirmed according to time. Stigmasterol exhibited the most stable pattern; l-methionine remained stable until day 14 and after day 21. This study was the first attempt to identify internal standard metabolites that were maintained at a constant level in a bloodstain for a sufficiently long time. Analysis of internal standard metabolites in bloodstains will facilitate determination of the initial blood volume from which the bloodstain was made. Moreover, this method will provide an approach for standardization of bloodstains to obtain absolute quantitative information of bloodstain components at crime scenes.

Estimation of Age of Bloodstains by Mass-Spectrometry: A Metabolomic Approach

Bloodstains are common evidence in crime scenes, containing significant information, including genetic information. Although efforts have been made to reliably determine the time of incident by analyzing the elapsed time of the bloodstain, there has been limited success. To identify candidate metabolites in bloodstains over time, we prepared bloodstain samples using filter paper and analyzed the metabolites by high-performance liquid chromatography-mass spectrometry (HPLC-MS)/MS over a 21-day period. Using Venn diagrams and by multivariate analysis, we selected 62 candidate molecular features. We found by partial least-squares discriminant analysis (PLS-DA) that the group can be classified with an accuracy of 75.0%, and the R² and Q² values were 0.7513 and 0.6998, respectively. Five metabolites were successfully identified based on candidate molecular features. The level of two metabolites, l-tryptophan and ergothioneine, decreased with time. The concentration of candidate metabolites that we propose reliably increased or decreased with time, thus, enabling the measurement of elapsed time of the bloodstain. This study is the first to identify markers used to analyze the elapsed time of bloodstains through metabolomics analysis.

Design of a heme-binding peptide motif adopting a β-hairpin conformation

Heme-binding proteins constitute a large family of catalytic and transport proteins. Their widespread presence as globins and as essential oxygen and electron transporters, along with their diverse enzymatic functions, have made them targets for protein design. Most previously reported designs involved the use of α-helical scaffolds, and natural peptides also exhibit a strong preference for these scaffolds. However, the reason for this preference is not well-understood, in part because alternative protein designs, such as those with β-sheets or hairpins, are challenging to perform. Here, we report the computational design and experimental validation of a water-soluble heme-binding peptide, Pincer-1, composed of predominantly β-scaffold secondary structures. Such heme-binding proteins are rarely observed in nature, and by designing such a scaffold, we simultaneously increase the known fold space of heme-binding proteins and expand the limits of computational design methods. For a β-scaffold, two tryptophan zipper β-hairpins sandwiching a heme molecule were linked through an N-terminal cysteine disulfide bond. β-Hairpin orientations and residue selection were performed computationally. Heme binding was confirmed through absorbance experiments and surface plasmon resonance experiments (K_D = 730 ± 160 nm). CD and NMR experiments validated the β-hairpin topology of the designed peptide. Our results indicate that a helical scaffold is not essential for heme binding and reveal the first designed water-soluble, heme-binding β-hairpin peptide. This peptide could help expand the search for and design space to cytoplasmic heme-binding proteins.

Silver nanoparticle-human hemoglobin interface: time evolution of the corona formation and interaction phenomenon

In this paper, we have used spectroscopic and electron microscopic analysis to monitor the time evolution of the silver nanoparticles (Ag NP)-human hemoglobin (Hb) corona formation and to characterize the interaction of the Ag NPs with Hb. The time constants for surface plasmon resonance binding and reorganization are found to be 9.51 and 118.48 min, respectively. The drop of surface charge and the increase of the hydrodynamic diameter indicated the corona of Hb on the Ag NP surface. The auto correlation function is found to broaden with the increasing time of the corona formation. Surface zeta potential revealed that positively charged Hb interact electrostatically with negatively charged Ag NP surfaces. The change in α helix and β sheet depends on the corona formation time. The visualization of the Hb corona from HRTEM showed large number of Hb domains aggregate containing essentially Ag NPs and without Ag NPs. Emission study showed the tertiary deformation, energy transfer, nature of interaction and quenching under three different temperatures.

A Raman "spectroscopic clock" for bloodstain age determination: the first week after deposition

Knowing the time since deposition (TSD) of an evidentiary bloodstain is highly desired in forensics, yet it can be extremely complicated to accurately determine in practice. Although there have been numerous attempts to solve this problem using a variety of different techniques, currently, no established, well-accepted method exists. Here, a Raman spectroscopic approach was developed for determining the age of bloodstains up to 1 week old. Raman spectroscopy, along with two-dimensional correlation spectroscopy (2D CoS) and statistical modeling, was used to analyze fresh bloodstains at ten time points under ambient conditions. The 2D CoS results indicate a high correlation between several Raman bands and the age of a bloodstain. A regression model was built to provide quantitative predictions of the TSD, with cross-validated root mean squared error and R (2) values of 0.13 and 0.97, respectively. It was determined that a "new" (1 h) bloodstain could be easily distinguished from older bloodstains, which is very important for forensic science in helping to establish the relevant association of multiple bloodstains. Additionally, all bloodstains were confirmatively identified as blood by comparing the experimentally measured spectra to multidimensional body fluid spectroscopic signatures of blood, saliva, semen, sweat, and vaginal fluid. These results demonstrate that Raman spectroscopy can be used as a nondestructive analytical tool for discriminating between bloodstains on the scale of hours to days. This approach shows promise for immediate practical use in the field to predict the TSD with a high degree of accuracy. Graphical Abstract Bloodstain aging over time illustrating naturally ocurring processes.

A molecular method to correlate bloodstains with wound site for crime scene reconstruction

Bloodstain pattern analysis to determine the wound-of-origin of bloodstains is problematic with nonspecific patterns. In this proof-of-concept study, the authors examined a molecular approach to correlate bloodstains with injuries using the rat as a model. Specifically, investigations were conducted on the rat brain marker, rno-miR-124-3p, with the QIAGEN miScript System and real-time PCR analysis. Rno-miR-124-3p was detected in brain homogenates diluted 100,000 times; in 3-week-old, room temperature stored, simulated brain-blood stains; and in bloodstains from head gunshot wounds collected with swabs and subsequently frozen for 9-18 months; however, rno-miR-124-3p was not detected in whole blood. Proof-of-principle was demonstrated by the ability to distinguish bloodstains from a gunshot wound to the head versus bloodstains from a gunshot wound to the chest, by the testing of otherwise identical bloodstains from the two patterns for the presence of the marker. The results suggest a viable approach to a longstanding problem in casework.

Lethal photosensitization of Porphyromonas gingivalis by their endogenous porphyrins under anaerobic conditions: an in vitro study

BACKGROUND

Lethal photosensitization has been previously demonstrated in Porphyromonas gingivalis, but oxygen is considered to be essential to this process. However, since P. gingivalis is a periodontal pathogen which grows in the low oxygen conditions found in the subgingival crevice, it was considered prudent to study its photosensitivity in anaerobic conditions.

METHODS

A series of experiments were undertaken to attempt to induce lethal photosensitization in P. gingivalis (ATCC 33277) under strict anaerobic conditions using two different 405 nm light sources. Samples of P. gingivalis were grown on a blood-containing, solid growth medium before being suspended in saline and then exposed to 405 nm light delivered by either a hand-held light source (Toothcare™) (11.4 mW/cm(2)) or a laser pointer (328.5 mW/cm(2)). With the exception of the adjustment of the P. gingivalis suspensions to a fixed optical density, the experiments were carried out in their entirety within an anaerobic chamber.

RESULTS

The lowest Toothcare light dose tested (0.34 J/cm(2); 30s) yielded a statically significant kill of 63.4% which increased to 94.1% kill at higher light doses (3.42 J/cm(2); 300 s). The laser pointer similarly achieved kills of 90.2% at the lower light dose tested (9.86 J/cm(2); 30s) and 94.5% kill at the highest light dose (98.55 J/cm(2); 300 s).

CONCLUSIONS

Lethal photosensitization can be instigated in planktonic suspensions of P. gingivalis at 405 nm delivered by hand-held devices under anaerobic conditions. This suggests the possibility that lethal photosensitization occurred by the oxygen-independent type I pathway as oppose to the oxygen-dependent type II pathway.