Fingerprint Residues Research Articles

A preliminary evaluation of the effects of aquatic environments on the recovery of fingermarks on porous substrates

Latent fingermark detection can become increasingly difficult in the weeks following deposition, due to chemical and physical changes influenced by environment. There has been increased research interest into ageing mechanisms of fingermark residue, however these studies have typically been conducted in dry, indoors conditions. Less information is available regarding degradation processes that may occur in scenarios involving water and the potential longevity of porous substrates under such conditions. A pilot study was conducted to investigate the performances of Oil Red O (ORO) and physical developer (PD) on samples submerged in different aquatic environments in a laboratory setting. Charged fingermarks from three donors were deposited on copy paper and immersed in either salt water or freshwater; still or with water flow. Samples were treated at multiple intervals (1, 12, 20 and 40 days) after submersion. Results showed that high quality of development could be achieved up to 40 days after immersion. The overall performances of ORO and PD were generally unaffected in the early stages of the study. Physical and chemical degradation of both latent residue and substrate were observed, which were increased by salt and water movement. While PD appeared to be less affected by potential chemical changes, it was less effective than ORO due to substrate degradation in moving salt water. These results present the first steps towards better understanding the practical effects of degradation processes specific to fingermarks on porous substrates underwater.

Desorption Electrospray Ionization Mass Spectrometry Imaging of Powder-Treated Fingermarks on Forensic Gelatin Lifters and its Application for Separating Overlapping Fingermarks.

Fingermarks are frequently collected at crime scenes by using gelatin lifters for preservation and transport of the marks to a forensic laboratory for inspection. The gelatin lifters preserve both the imprint of the fingermark pattern necessary for identification purposes and the chemical residue of the mark potentially useful for profiling the person who left the fingermark. The fingermark patterns are traditionally recorded using photography/optical imaging, but methods for chemical analysis of fingermark residues on gelatin lifters are scarce. Here we report the first method for the chemical analysis of fingermarks on gelatin lifters using desorption electrospray ionization mass spectrometry (DESI-MS) imaging. The imaging can be done directly on the gelatin support without any sample preparation, supporting immediate operational use of the method for fingermarks collected at crime scenes. Operational use of the method is further supported by successful chemical imaging of fingermarks enhanced by traditional dusting with forensic powders and lifted off different surfaces (glass, stainless steel, painted aluminum, polystyrene, cardboard, and plastic) as well as fingermarks lifted multiple times. We also demonstrate that the present method can be used to visually separate natural overlapping powder-treated fingermarks, and the chemical composition of the fingermarks can be analyzed on the gelatin support by DESI-MS/MS. The presented method has potential for integration into the traditional workflow for fingermark analysis, and will allow more fingermarks collected at crime scenes to be evaluated both visually and chemically.

Non-destructive and simultaneous development and enhancement of latent fingerprints on stainless steel based on the electrochromic effect of electrodeposited manganese oxides

Latent fingerprints, as one of the most frequently encountered traces in crime scene investigation and also one of the largest sources of forensic evidence, can play a critical role in determining the identity of a person who may be involved in a crime. Due to the invisible characteristic of latent fingerprints, exploring efficient techniques to visualize them (especially the ones resided on metallic surfaces) while retain the biological and chemical information (e.g., touch DNA) has become a multidisciplinary research focus. Herein we reported a new and highly sensitive electrochemical interfacial strategy of simultaneously developing and enhancing latent fingerprints on stainless steel based on synchronous electrodeposition and electrochromism of manganese oxides in a neutral aqueous electrolyte. By utilizing a specially designed device for electrochemical testing and image capture, a series of electrochemical measurements, physical characterization and image analysis have been applied to evaluate the feasibility, development accuracy and enhancement efficacy of the proposed electrochemical system. The qualitative and quantitative analysis on the in situ and ex situ fingerprint images indicates that the three levels of fingerprint features can be precisely developed and effectively enhanced. Forensic DNA typing has also been performed to reveal actual impact of the proposed electrochemical system on subsequent analysis of touch DNA in fingerprint residues. The ratio of detected loci after electrochemical treatment reaches up to 98.5 %, showing non-destructive nature of this fingerprint development and enhancement technique.

Showcasing water-based delivery of an amino acid targeting fingermark developer in a hydrogel

Most recommended methods for visualising fingermarks on paper rely on chemical developers that target and react with amino acids. Traditionally, these developers are sprayed onto paper substrates in solutions of per- and polyfluoroalkyl substances (PFAS), but now those same PFAS chemicals are undergoing phaseout or phasedown, which threatens to undermine forensic capabilities. This situation provides an opportunity to pivot towards greener approaches to fingermark visualisation. The ideal methodology would be a water-based treatment, as these provide superior safety for practitioners, combined with environmental sustainability. A major hurdle to implementing a water-based fingermark developer targeting amino acids is that water, as a universal solvent, can dissolve the eccrine components in fingermarks, as well as any optical or luminescent dyes that are created, causing the ridge detail to run or dissolve. This work circumvents this problem by delivering the amino acid developer alloxan in a hydrogel, which enables sharp fingermark ridge details to be observed despite it being a water-based treatment. Alloxan dissolved in a viscous hydrogel is shown here to react with the amino acids in fingerprint residues to form the coloured dye murexide, supported by optimisation and characterisation studies.

Role of doped ZnO variants for the development of latent fingerprint

Here we are presenting a promising approach for the green synthesis of zinc oxide (ZnO) nanomaterials by using lemon grass with minimal environmental impact. The fabricated zinc oxide (ZnO) doped with different dyes ranging from 25 −100 nm were applied to read the minutiae points of finger prints that can lead for person identification. In this model project, we doped different dyes on ZnO and used for the development of latent finger prints on different surfaces and at time duration (1 h to 24 h). The linkage between nanomaterials and fingerprint residues is among oxide group and amine group. We presented that these designed materials have the ability to develop fingerprints on variety of substrates. We displayed that with the passing of time the chroma index and intensity reduce but still at 24 h we can read the minutiae details. This research opens a new era to enhance and quantifying contrast between surface and applied material.

DNA recovery after sequential processing of latent fingerprints on black polyethylene plastic.

Latent fingerprints on plastic substrates can be visualized by using sequential treatments to enhance the contrast between the fingerprint residues and underlying substrate; however, the extent to which these processes affect subsequent DNA analysis is mostly unknown. Latent fingerprints deposited on black plastic by one donor were visualized with single-process fingerprint powders (i.e., white powder, bichromatic powder, or bichromatic magnetic powder) or sequential treatments (i.e., laser → reflected ultraviolet imaging system (RUVIS) → CA fuming → RUVIS → Rhodamine 6G, Ardrox, and MBD (RAM) or CA fuming → RAM/laser → bichromatic magnetic powder). Samples were examined after the addition of each treatment. DNA was collected using cotton swabs, extracted, quantified, and amplified. DNA yields, peak heights, number of alleles obtained, and percentage of DNA profiles eligible for CODIS upload were examined. Latent fingerprints processed with the laser and up to three sequential treatments generated DNA profiles with significantly higher peaks heights than those of the untreated samples. Fingerprints processed with the laser and up to two sequential treatments generated DNA profiles with significantly more alleles. All methods beginning with laser enhancement generated more CODIS-eligible profiles. Additional research is needed to determine the extent to which initial laser enhancement impacts the success of downstream DNA profiling results. Although DNA profile development is not guaranteed due to the variable quantities of DNA contained within latent fingerprints, the selection of an appropriate latent fingerprint visualization method could maximize both fingerprint detection and the generation of CODIS-eligible DNA profiles.

Endowing an amphiphilic aggregation-induced emission molecule with turn-on fluorescence in both latent fingerprints development and antibiotics detection

The water-soluble aggregation-induced emission (AIE) molecule is desirable as a turn-on fluorescence probe, but it is challenging because most AIE-based molecules are lipophilic and can emit strong fluorescence in water. To address the problem, tetraphenylethene (TPE) backbones are decorated with hydrophilic pyridine ethanol-related groups, and a series of novel amphiphilic TPE-based pyridinium salts (denoted as TPE-Py-OH, TPE-2Py-2OH and TPE-4Py-4OH) are synthesized. Encouragingly, TPE-2Py-2OH aqueous solution which is almost non-emissive can be used as a bifunctional turn-on fluorescent probe for developing latent fingerprints (LFPs) and detecting antibiotics. Level 3 details in LFPs are developed via soaking/ spraying method, owing to that AIE phenomenon is activated by the combination of lipophilic part in TPE-2Py-2OH and fatty acid residues in fingerprints. The method is worthy to promote, because it displays the advantages of water solubility, low working concentration, ease of operation, good stability, high safety, high contrast, high sensitivity, and high selectivity. It can also response to penicillin potassium (PNG) with a detection limit of 0.18 μM because the electrostatic interaction between TPE-2Py-2OH and PNG can mainly induce the enhanced fluorescence. This discovery provides a facile approach to design more promising amphiphilic AIE-based turn-on fluorescence probes.

(Invited) Exploitation of Electron Transfer Reactions for Latent Fingerprint Visualization: Fundamental Concepts and Technology Transfer

A fingerprint is a unique time-invariant attribute of an individual and is the most frequent physical evidence used to identify a suspect in a criminal investigation. An image of the fingerprint left on a surface by the transfer of material between the fingertip and the surface can establish contact between the individual and an object (e.g. weapon) or a fixed location (crime scene). In practice, most marks are so-called latent (non-visible) fingermarks that require chemical treatment to generate a visible image. This presentation describes the contribution of electron transfer reactions (redox processes) to this endeavor and reveals the variety of reaction type, reagent materials, and substrate surfaces.The key to a successful fingermark reagent is the facility to deliver it with high spatial selectivity to either the deposited residue (representing ridges on the finger) or the bare substrate (representing furrows on the finger), such that there is visual contrast between the ridge and furrow areas. The lateral (horizontal) patterning of so-called second level features (such as ridge endings, crossovers and bifurcations) is the basis of the identification. Superficially, the distance scale is macroscopic (ridge width ca. 100 mm), but the aspiration of a suitably sharp image involves so-called third level detail at the mesoscopic level (ridge edge shape resolution ca. 1 mm). However, this lateral image quality requires vertical control of reagent deposition at the nanoscale. Here we explore how latent fingermark visualization can be accomplished by controlled molecular mechanisms involving metallic and polymeric materials.Two established (but previously poorly mechanistically understood) metal deposition processes are physical developer (PD) and multi-metal deposition (MMD). PD involves redox generation of silver nanoparticles that deposit selectively on fingermark residue on paper substrates (e.g., documents, correspondence, paper currency). We show how mechanistic understanding [1] of a recent PD re-formulation [2] has been used to overcome the environmental outlawing of a critical surfactant in the classical process, revealing latent marks up to a century after deposition. MMD is a more sophisticated variant, in which gold nanoparticles are pre-deposited on the residue and act as nucleation sites for silver deposition to reveal marks on thin plastic films (e.g., drugs and explosives wrappings). We show how the kinetics of redox-driven silver deposition on ridge vs furrow regions define image contrast.In a complementary strategy, we use the fingerprint residue as a template (“mask”) to direct electrochemically generated reagent to the bare surface between the deposited ridges, creating a negative image of the fingerprint. When the surface is a reactive metal (Cu or Fe), a more noble metal (Ag) can oxidize exposed substrate atoms. The electron transfer process results in solution oxidant (here, Ag) being reduced to elemental metal that deposits on the surface and dissolution of an equivalent amount of substrate. Complexing agents influence both reaction thermodynamics and kinetics. Optical and SEM imaging and EDAX surface analysis reveal high quality images with clear third level detail.When the surface is an inert metal, exemplified by stainless steel (forensically relevant to knife crime), the above galvanic exchange cannot take place. In this instance, electrochemically driven oxidation of aromatic monomers creates negative images of latent marks via polyaniline [3], PEDOT [4] or poly(pyrrole-co-EDOT) [5] films. We show how these electrochromic systems offer the prospect of optimization of visual contrast via light absorption. More recently, we have explored the prospect of incorporating fluorescent dyes (Methyl Red, Methyl Orange, Indigo Carmine, Basic Yellow 40) in the polymer films, using functionalization, ion-exchange and physical encapsulation strategies [6].We discuss the practicalities and prospects for technology transfer of these approaches to the practitioner environment; even for the nominally established PD and MMD processes, this is not trivial. Positive outcomes lie at the core of collaborative expertise provided by practitioners, researchers, regulatory authorities and investigators. We discuss how this can be realized through engagement of these parties and researcher use of the image capture and enhancement technologies used by practitioners.

Development of latent fingerprints by degradable highly-adhering powder——a long-term strategy for the fading of fingerprint residues

The development of highly efficient and harmless reagent for visualization of latent fingerprints (LFPs) on variety substrates is of great importance for criminal investigations. Herein, a kind of “green” and cost-effective fingerprint development powder (polydopamine nanospheres, PDA NSs) is facilely synthesized via self-polymerization of dopamine under mild condition. Due to the abundant functional groups (catechol and amine), PDA-based powder can firmly adhere to the fingerprint residues via supermolecule interactions on various substrates (permeable or not) rapidly. The apparent LFPs from male or female were successfully obtained and analyzed. The fingerprint images exhibited clear first level (fingerprint patterns) and second level (detail features) fingerprint information on the challenging substrates (colored lid, cambered cup, paper, wood, and leather). Even fingerprint aged for more than 90 days on the non-permeable substrate surface can be recognized obviously with extremely lower detection limit. In addition, the gray value analysis further verified the advantage of PDA-based fingerprint development with good contrast, resolution and selectivity. Moreover, the excellent properties of the novel PDA NSs powder endow it highly competitiveness to the commercial low hazard black magnetic powder, which may be expected to make it become an attractive nanomaterial in crime scenes and forensic investigations.

ZnO@SiO2 Nanocapsules: Efficient Fluorescence for Latent Fingerprint Detection

AbstractAs advanced fingerprint powders, fluorescent materials generally provide high sensitivity and improved contrast on the pigments or patterned surface, with high resolution. In this study, ZnO nanoparticles are used as fluorescent materials and are homogeneously embedded into SiO2 matrix to prepare ZnO@SiO2 nanocapsules. Compared with conventional methods, ZnO@SiO2 nanocapsules are fabricated using the transparent ethanol solution of ZnO NPs and n‐Octyltriethoxysilane without any surfactants. Interestingly, a large number of ZnO NPs can be homogeneously embedded in the silica matrix, reducing the aggregation‐induced quenching effect. The maximum emission of the ZnO@SiO2 nanocapsules powder is located at 530 nm under 325 nm irradiation, and the photoluminescence intensity and the sensitivity of latent fingerprints development depend on the quantity of ZnO NPs in the composites. The prepared fluorescent ZnO@SiO2 nanocapsules show outstanding property applied as effective fluorescent eikonogens for the high‐sensitivity visualization of latent fingerprints on different porous and non‐porous substrates. It has been demonstrated that ZnO@SiO2 nanocapsules compounds combine the admirable adhesion of silica powders to fingerprint residues with the excellent photoluminescence properties of ZnO to form a promising light‐emitting material for fingerprint.

Preferential Contamination in Electroadhesive Touchscreens: Mechanisms, Multiphysics Model, and Solutions

AbstractElectroadhesive surface haptic touchscreens can help augment user experiences by providing tactile effects. The electrode layout in current commercialized designs has separated electrodes for the sensing and actuating functions. During regular use, it is observed that fingerprint residue preferentially deposits on the actuating electrodes far more than the sensing electrodes, which makes the underlying electrode pattern apparent and is highly undesirable for touchscreen users. To address this issue, various physical phenomena (electrohydrodynamic deformation, capillary bridge stabilization, electrowetting, and electrophoretic deposition) are investigated to understand the mechanism. Through experimentation, multiphysics modeling, and surface characterization, it is found that the root cause can be attributed to two mechanisms occurring in the actuating regions: 1) electrohydrodynamic deformation of sebum droplets attached to the finger valleys leading to the formation of additional capillary bridges and residual droplets on the screen surface after their rupture, and 2) electric field‐induced stabilization of sebum capillary bridges existing between the finger ridges and the screen, leading to the coalescence and formation of larger‐sized droplets. The developed model can then be used to address the issue during the screen design process. An example of using the model to explore the impact of changes in screen oleophobicity is shown.

Can latent fingerprint disclose the sex of the donor? A preliminary test study using GC-MS analysis of latent fingerprints.

While fingerprints are a highly used means of identification, not every fingerprint left behind on a potential crime scene can be used for identification purposes. In some cases, the fingerprint may be smudged, partially preserved or overlapping with other prints hence distorting the ridge pattern and may therefore be not appropriate for identification. Further, fingermark residue yields a very low abundance of genetic material for DNA analysis. In such cases, the fingermark may be used to retrieve basic donor information such as sex. The focus of this paper was to assess the possibility of differentiating between the sexes of the donor of latent fingermarks. Analytical method was GC-MS analysis of the chemical compounds of latent fingermarks using 22 male and 22 female donors. Results showed 44 identified compounds. Two alcohols, octadecanol C18 and eicosanol C20 , were found to show a difference that was statistically significant between male and female donors. There is also some evidence for the possibility of distinguishing sex of the fingermark donor based on the distribution of branched chain fatty acids, as free compounds or esterified in wax esters.

Use of conductive Ti2O3 nanoparticles for optical and electrochemical imaging of latent fingerprints on various substrates

The personal identification technology based on fingerprint features has great application value in the fields of public security and consumer electronics due to its extensiveness and reliability. However, current fingerprint development methods do not work efficiently for latent fingerprints (LFPs) deposited on some problematic objects. In this work, conductive Ti2O3 nanoparticles (NPs) with black color were used as a novel optical and electrochemical dual-mode enhancer for the development of LFPs with high sensitivity, resolution and low background interference on various substrates. For the majority of substrates, black Ti2O3 NPs were able to acquire the high-sensitivity optical development of LFPs (levels 1–3 features), which maybe result from spatially selective adhesion between Ti2O3 NPs and fingerprint residues. However, for dark substrates with strong background color interference, the obtained images from Ti2O3-developed fingerprints were severely blurry. Significantly, by virtue of the electroactivity of Ti2O3 powder, the Ti2O3-developed fingerprints could be further electrochemically imaged with high contrast and high resolution by scanning electrochemical microscopy (SECM) to eliminate background color interference. The current changes at the probe of SECM could reflect the pattern information of the fingerprint because the redox mediator could be regenerated at the surface of Ti2O3 powders adhered to the ridge regions. These results demonstrated that Ti2O3 NPs could be considered as a bi-functional developer for enhancing LFPs.

Differentiating individuals through the chemical composition of their fingermarks

Fingermark patterns are one of the oldest means of biometric identification. During this last decade, the molecules that constitute the fingermark residue have gained interest among the forensic research community to gain additional intelligence regarding its donor profile including its gender, age, lifestyle or even its pathological state. In this work, the molecular composition of fingermarks have been studied to monitor the variability between donors and to explore its capacity to differentiate individuals using supervised multi-class classification models. Over one year, fingermarks from thirteen donors have been analysed by Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (n = 716) and mined by different machine learning approaches. We demonstrate the potential of the fingermark chemical composition to help differentiating individuals with an accuracy between 80% and 96% depending on the period of sample collection for each donor and size of the pool of donors. It would be premature at this stage to transpose the results of this research to real cases, however the conclusions of this study can provide a better understanding of the variations of the chemical composition of the fingermark residue in between individuals over long periods and help clarifying the notion of donorship.

Physical visualization and squalene-based scanning electrochemical microscopy imaging of latent fingerprints on PVDF membrane.

Fingerprints have long been the gold standard for personal identification in forensic science. However, realizing the high-resolution enhancement of eccrine LFPs is difficult using the traditional methods and the label-free detection of fingerprint residue information is also challenging. Herein, we propose two enhancement strategies for LFPs on PVDF membrane (LFPs/PVDF) using blue-black ink staining and scanning electrochemical microscopy (SECM). The blue-black ink staining method was used for the first time to develop three types (sebaceous, natural and eccrine) of LFPs/PVDF based on the difference in wettability between the fingerprint residues and PVDF membrane. The enhanced fingerprints clearly displayed levels 1-3 features with high contrast and low background interference. Furthermore, we achieved chemical imaging of the LFP/PVDF samples, where their possible visualization mechanisms were ascribed to the electrochemical reactivity of squalene and difference in wettability between the LFP and PVDF membrane, which was first proposed and investigated by SECM imaging and water contact angle (WCA) measurements, respectively. Significantly, SECM imaging not only provided fingerprint patterns without any labelling but also revealed the spatial distribution information of squalene in LFPs simultaneously. In addition, it was also demonstrated that LFPs deposited on various surfaces were first successfully transferred to the PVDF membrane, and then further developed with both methods, making them general for personal identity-related applications. Taken together, the blue-black ink staining method can easily and quickly obtain level 3 features of LFPs/PVDF and the SECM approach can non-invasively image the topography and chemical information of LFPs/PVDF, and thus they can be potentially selected according to various requirements in forensic scenarios.

Nanosheets of two-dimensional photoluminescent lanthanide phosphonocarboxylate frameworks decorated with free carboxylic groups for latent fingerprint imaging.

The synthesis, structural characterization, exfoliation, and photophysical studies of two-dimensional (2-D) lanthanide phosphonates, named Ln(m-pbc); [Ln(m-Hpbc)(m-H2pbc)(H2O)] (Ln = Eu, Tb; m-pbc = 3-phosphonobenzoic acid) based on the phosphonocarboxylate ligand, are reported. These compounds are neutral polymeric 2D layered structures with pendent uncoordinated carboxylic groups between layers. The nanosheets were obtained by a top-down strategy involving sonication-assisted solution exfoliation and characterized by atomic force microscopy and transmission electron microscropy, showing lateral dimensions from nano- to micro-meter scales, and thicknesses down to several layers. The photoluminescence studies demonstrate that the m-pbc ligand acts as an efficient antenna toward Eu and Tb(III) ions. The emission intensities of dimetallic compounds are clearly enhanced after incorporation of Y(III) ions due to the dilution effect. Ln(m-pbc)s were then applied for labelling latent fingerprints. It is worth noting that the reaction between active carboxylic groups and fingerprint residues benefits the labelling, showing efficient imaging for fingerprints on all kinds of material surfaces.

A REVIEW STUDY ON DETECTION OF COCAINE FROM FINGERPRINT RESIDUE

Illicit drug trafficking and drug abuse are highly reported crimes around the world. Detection of criminals in such types of cases are often very difficult. It is expected that criminals’ fingerprint residue will have traces of such evidence and will leave behind at scene of occurrence. Researchers have reported so many analytical techniques i. e. Raman Spectroscopy, Mass spectrometric analysis techniques such as PS-MS, LC-MS-MS, and imaging techniques such as ATR-FTIR for extraction and quantitative analysis of such drugs from remnants. This study is an attempt to trace the evidences of cocaine from fingerprint residue and to detect external deposition of cocaine either from primary contact or secondary contact can be detected based on concentration variations. Excretion of cocaine metabolites through sweat can be detected from fingerprint residue using mass spectrometric analysis techniques as well as immunoassays. The result of this study will encourage the researchers for the extraction of drug particles from fingerprints and apprehend the people involved in crime related to drugs.

From nanomaterials to macromolecules: Innovative technologies for latent fingerprint development

AbstractThe majority of conventional techniques for latent fingerprint enhancement are based on chemical reactions or interactions between the developer and fingermark residue components, providing contrast between the surface and the fingerprint ridges. However, these methods might be limited by factors associated with particle size, toxicity of the reagent, selectivity, or sensitivity, that may be circumvented by the synthetic design of innovative materials based on nanoparticles or macromolecular materials, such as conducting polymers, applied as latent fingerprint developers on different surfaces and conditions. Since the structural, optical and electronic properties of the material can be tailored by its molecular scale, the size control of the developer plays an important role to improve the interaction with the latent fingermark residue and/or the surface, enhancing the color contrast and the quality of the developed image (or dactylogram). Hence, creating new reagents and strategies to apply nano‐ and macromolecular scale materials as latent fingermark developers constitutes an exciting rapidly expanding area, generating a wealth of new materials that lead to forensic methodologies with enhanced performance. Recent progress in the application of such materials for development of latent fingermarks present on different surfaces and subject to complex circumstances will be discussed. This will focus on the main barriers to making nanoparticles and conducting polymers viable—and occasionally preferred—materials routinely used by forensic experts, and the potential advantages over conventional methodologies in the acquisition and analysis of crime scene evidence.This article is categorized under: Forensic Chemistry and Trace Evidence > Trace Evidence Forensic Chemistry and Trace Evidence > Fingermarks and Other Marks Forensic Chemistry and Trace Evidence > Emerging Technologies and Methods

Molecular docking study on europium nanoparticles and mussel adhesive protein for effective detection of latent fingerprints

Background: Reflecting on the difficulty of finding the evidence of latent fingerprints on wet and rough surfaces, scientists need to visualise those fingermarks without any background interference and stable adhesion of visualising material over the fingermark residues. Objective: To stabilize the interaction with the fingermarks, the synthesized nanoparticles were conjugated with a highly adhesive biopolymer, Mussel Adhesive Protein (MAP) which can effectively interact with fingerprint deposits. Material and Methods: Rare earth metal, europium oxide and nanoparticles were used as a visualisation material to get high contrast and reduced background interference-based fingerprints. To stabilise the interaction with the fingermarks, the synthesised nanoparticles were conjugated with highly adhesive biopolymer, Mussel Adhesive Protein (MAP) which can effectively interacts with fingerprint deposits. A molecular docking study was done using Auto-Dock to find the binding affinity between the metal nanoparticle and the protein. Further, the stability of the bioconjugated with fingerprint residues was analysed by protein-protein interaction study through patch dock and PDB Sum. Results: The docking analysis between europium and nanoparticles with MAP was found to be −8.77 kcal/mol and −47.49 kcal/mol respectively. Protein-protein interaction studies showed a highest affinity for dermcidin and keratin with a binding affinity of −16.76 kcal/mol and −24.76 kcal/mol respectively. Conclusions: The docking studies showed an efficient interaction between the synthesised molecules and the fingermark residues. Results of these interaction studies proved that this bio-conjugated complex can be explored for efficient visualisation of low intensified fingermarks.

Hydrophobic‐Binding‐Driven and Fluoresence‐Free Development of Aged Fingerprints Based on Zinc Oxide Nanoparticles

AbstractThe requirement of nonfluorescent developers for aged latent fingerprint development is still of great urgency in forensic science. To enhance the specific interaction between fingerprint residue and nano‐developers, a γ‐methacryloxy propyl trimethoxyl silane (MPTS) modified zinc oxide nanoparticle (ZnO NP) was synthesized. The crystal structure, morphology, surface functional group, thermostability, UV/Vis spectra, photoluminescence and stability of sedimentation were characterized to prove the hydrophobicity, UV blocking nature and nonfluorescence of as‐prepared MPTS‐modified ZnO NPs. Additionally, after the specific surface area (SSA) of samples with different MPTS amount was analyzed by BET, a competitive adsorption mechanism between silane‐ZnO bonding and silane oligomer‐ZnO deposition was suggested. In the demonstration of latent fingerprint development, the powder dusting method was utilized on various surfaces both in positive and reversed imaging modes, exhibiting the high contrast, high sensitivity, high selectivity and wide applicability, even for aged fingerprints. Therefore, it provides a new strategy for fast, efficient and inexpensive development of older latent fingerprints in forensic analysis.