Conjugation of visual enhancers in lateral flow immunoassay for rapid forensic analysis: A critical review.

During crime scene investigations, numerous traces are secured and may be used as evidence for the evaluation of source and/or activity level propositions. The rapid chemical analysis of a biological trace enables the identification of body fluids and can provide significant donor profiling information, including age, sex, drug abuse, and lifestyle. Such information can be used to provide new leads, exclude from, or restrict the list of possible suspects during the investigative phase.

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.

Analysis of the fluorescent properties of vaginal fluid upon ageing.

Detection and identification of body fluids are crucial aspects of forensic investigations, aiding in crime scene reconstructions and providing important leads. Although many methods have been developed for these purposes, no method is currently in use in the forensic field that allows rapid, non-contact detection and identification of vaginal fluids directly at the crime scene. The development of such technique is mainly challenged by the complex chemistry of the constituents, which can differ between donors and exhibits changes based on woman's menstrual cycle.

DFT Study of Imine-Exchange Reactions in Iron(II)-Coordinated Pincers.

The imine bond is among the most applied motifs in dynamic covalent chemistry. Although its uses are varied and often involve coordination to a transition metal for stability, mechanistic studies on imine exchange reactions so far have not included metal coordination. Herein, we investigated the condensation and transimination reactions of an Fe -coordinated diimine pyridine pincer, employing wB97XD/6-311G(2d,2p) DFT calculations in acetonitrile.

Use of Lateral Flow Assays in Forensics.

Already for some decades lateral flow assays (LFAs) are 'common use' devices in our daily life. Also, for forensic use LFAs are developed, such as for the analysis of illicit drugs and DNA, but also for the detection of explosives and body fluid identification. Despite their advantages, including ease-of-use, LFAs are not yet frequently applied at a crime scene.

Towards Onsite Age Estimation of Semen Stains Using Fluorescence Spectroscopy.

The age estimation of biological traces is one of the holy grails in forensic investigations. We developed a method for the age estimation of semen stains using fluorescence spectroscopy in conjunction with a stoichiometric ageing model. The model describes the degradation and generation rate of proteins and fluorescent oxidation products (FOX) over time.

Specific fluorescent signatures for body fluid identification using fluorescence spectroscopy.

Non-invasive, rapid, on-site detection and identification of body fluids is highly desired in forensic investigations. The use of fluorescence-based methods for body fluid identification, have so far remain relatively unexplored. As such, the fluorescent properties of semen, serum, urine, saliva and fingermarks over time were investigated, by means of fluorescence spectroscopy, to identify specific fluorescent signatures for body fluid identification.

Characterising extracellular vesicles from individual low volume cerebrospinal fluid samples, isolated by SmartSEC.

Extracellular vesicles (EVs) are suggested to have a role in the progression of neurodegeneration, and are able to transmit pathological proteins from one cell to another. One of the biofluids from which EVs can be isolated is cerebrospinal fluid (CSF). However, so far, few studies have been performed on small volumes of CSF.

Improving the visualization of fingermarks using multi-target immunolabeling.

The development of fingermarks is an important step in visualizing ridge patterns for individualization purposes. Immunolabeling can be applied to fingermarks to selectively and sensitively detect antigens in fingermarks, and can be used as a developing method to visualize fingermarks. In this study we investigated single (the detection of one antigen) and multiple targeting approaches (the detection of multiple antigens simultaneously) to improve fingermark development.

The compatibility of immunolabeling with STR profiling.

Immunolabeling is a technique, which has recently been introduced to enhance the quality of developed fingermarks and subsequently strengthen the evidential value. The effect of this method on subsequent DNA analysis, however, has not been explored yet. Therefore, the current pilot study aimed to determine whether STR profiling is possible after immunolabeling.

Human milk triggers coagulation via tissue factor-exposing extracellular vesicles.

Almost a century ago, it was discovered that human milk activates the coagulation system, but the milk component that triggers coagulation had until now been unidentified. In the present study, we identify this component and demonstrate that extracellular vesicles (EVs) present in normal human milk expose coagulant tissue factor (TF). This coagulant activity withstands digestive conditions, mimicking those of breastfed infants, but is sensitive to pasteurization of pooled donor milk, which is routinely used in neonatal intensive care units.

Detection of extracellular vesicles in plasma and urine of prostate cancer patients by flow cytometry and surface plasmon resonance imaging.

Large (> 1 μm) tumor-derived extracellular vesicles (tdEVs) enriched from the cell fraction of centrifuged whole blood are prognostic in metastatic castration-resistant prostate cancer (mCRPC) patients. However, the highest concentration of tdEVs is expected in the cell-free plasma fraction. In this pilot study, we determine whether mCRPC patients can be discriminated from healthy controls based on detection of tdEVs (< 1μm, EpCAM+) and/or other EVs, in cell-free plasma and/or urine.

The use of crime scene detection dogs to locate semen stains on different types of fabric.

In sexual assault cases, the detection and identification of semen is extremely important as this type of evidence can be used as a source for investigative leads and contributes to case evidence. However, the detection of semen stains is often difficult, even indoors, because of different (environmental) factors, such as substrate type, coloured items and large search areas. In 2015, a project was initiated by the Dutch police to evaluate the feasibility of the use of detection dogs to locate semen stains in forensic practise.

Estimating the Time of Deposition of Semen Traces using Fluorescence Protein-Lipid Oxidation Signatures.

In the forensic field, knowledge about the time of deposition of semen traces is extremely valuable to law enforcement agencies to assess the relevance of the traces and the validity of witness testimonies. However, currently, no method exists that is able to estimate the time of deposition of semen stains, due to the complex chemistry of the constituents and variation in degradation patterns. Here, we demonstrate a non-contact age estimation method to assess the time of deposition of semen stains using fluorescence spectroscopy.

Prediction of DNA concentration in fingermarks using autofluorescence properties.

During criminal investigations trace DNA samples, including fingermarks, are submitted to laboratories for short tandem repeat (STR) analysis. For most common STR analysis systems a minimum amount of input DNA is required. Upon intake by the forensic laboratory the DNA concentration is estimated using quantitative polymerase chain reaction (qPCR) analysis after which most fingermarks are excluded.

Identification and detection of protein markers to differentiate between forensically relevant body fluids.

The identification of body fluids at a crime scene is an important aspect of forensic casework analysis, being a source for investigative leads and contributing to case evidence. Yet, current methods for the forensic identification of body fluids suffer from several limitations, ranging from poor sensitivity and specificity, to sample destruction and interference with subsequent DNA analysis. Moreover, current identification assays target only one body fluid at the time.

Techniques that acquire donor profiling information from fingermarks - A review.

Fingermarks are among the most important types of evidence that can be encountered at the scene of a crime since the unique ridge pattern of a fingerprint can be used for individualization. But fingermarks contain more than the characteristic pattern of ridges and furrows, they are composed of a wide variety of different components that originate from endogenous and exogenous sources. The chemical composition can be used to obtain additional information from the donor of the fingermark, which in turn can be used to create a donor profile.

On the autofluorescence of aged fingermarks.

Fingermark autofluorescence changes with time, both spectrally and in total intensity. In this study we investigate which components in the aged fingermarks cause this change in autofluorescent signal. Thin layer chromatography combined with fluorescence spectroscopy was used to identify fluorescent aging products.

Immunolabeling and the compatibility with a variety of fingermark development techniques.

Much information can be obtained from the chemical composition of a fingermark, which can be helpful in crime scene investigation. Immunolabeling can be used to extract information about the donor of the fingermark and it can also act as a fingermark development tool in sequence with the standard fingermark development techniques. However, before immunolabeling can be used in forensic practice more information on the possibilities and limitations of this technique is required.

Oxidation monitoring by fluorescence spectroscopy reveals the age of fingermarks.

No forensic method exists that can reliably estimate the age of fingermarks found at a crime scene. Information on time passed since fingermark deposition is desired as it can be used to distinguish between crime related and unrelated fingermarks and to support or refute statements made by the fingermark donors. We introduce a non-contact method that can estimate the age of fingermarks.

Simultaneous labeling of multiple components in a single fingermark.

A fingermark contains important forensic information of the donor, not only in its ridge pattern, but also in the chemical composition of its secretion. Detection and identification of these secretions can be done by immunolabeling. In this study, we describe for the first time a reproducible immunolabeling method that allows the simultaneous detection of multiple components of interest.

The compatibility of fingerprint visualization techniques with immunolabeling.

The chemical composition of a fingermark potentially holds a wealth of information about the fingermark donor, which can be extracted by immunolabeling. Immunolabeling can be used to detect specific components in fingermarks; however, to be applicable in the forensic field, it should be compatible with commonly used fingerprint visualization techniques. In this study, the compatibility of immunolabeling with two different fingerprint visualization techniques, magnetic powdering and ninhydrin staining, was investigated on fingermarks deposited on glass and on nitrocellulose membranes.