1 Vol.:(0123456789) Scientific Reports | (2022) 12:14780 | https://doi.org/10.1038/s41598-022-18929-8 www.nature.com/scientificreports Preliminary forensic assessment of the visualised fingerprints on nonporous substrates immersed in water using the green and optimised novel nanobio‑based reagent Aida Rasyidah Azman 1,2* , Naji Arafat Mahat 1,2,3* , Roswanira Abdul Wahab 1,2 , Wan Azlina Ahmad 1 & Dzulkiflee Ismail 4 The discovery of forensic evidence (e.g. weapons) during forensic underwater investigations has seen an increasing trend. To date, small particle reagent (SPR) has been one of the routinely used methods for visualising fingerprints on wet, non‑porous substrates. However, the long term use of SPR is detrimental to humans and environment due to the use of toxic chemicals. Although previously we have successfully developed and optimised a greener nanobio‑based reagent (NBR), its suitable practical use in a more realistic scene (e.g. outdoor pond) was not evaluated. Therefore, this present research is aimed at (1) investigating the performance of NBR against the benchmark SPR in visualising fingerprints immersed in a natural outdoor pond and (2) evaluating the greenness of NBR against the analytical Eco‑Scale. Results showed that the performance of the optimised NBR was mostly comparable (University of Canberra (UC) comparative scale: 0) with SPR at visualising fingerprints on three different non‑porous substrates immersed in a natural outdoor pond. Observably, the NBR had higher preference towards aged fingerprints (up to 4 weeks of immersion). In addition, its greenness assessment revealed 76 points, indicating ‘excellent green analysis’. The findings gathered here further supported the practical use of the NBR in forensic investigations. Over the years, fingerprints have been globally considered the benchmark for identifying a suspect, victim or witness for forensic investigations 1 . A unique identifier on its own, fingerprints consists of a series of random ridges and furrows formed within 6–25 weeks of human fetal development 2 , supporting the fact that no two individuals have the same fingerprints 1 . Forensically, fingerprints found at crime scenes can be of patent, plastic, or the most common, latent in nature 3 . Because the latter demands the use of suitable optical, physical, and/or chemical visualisation methods to be observable by naked human eyes, continuous method developments for visualising such prints have been frequently observed 4–6 . Nevertheless, the nature of the substrate (e.g. porosity and wetness) plays an important role in selecting the suitable method to visualise the latent prints. It is important to highlight here that fingerprints are made up of eccrine (e.g. water, proteins and amino acids) and sebaceous (e.g. fatty acids and wax esters) constituents as well as other contaminants (e.g., cosmetics and bacteria) 7 . Expectedly, fingerprints leſt on wet substrates would only have a minute amount of non-water-soluble constituents, considering the water might have dissolved the water-soluble ones. erefore, fingerprints subjected to destructive environments, like those found during underwater forensic investigations, further complicate the visualisation process. On the other hand, it has been reported that ‘criminals oſten seek a watery repository for OPEN 1 Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. 2 Enzyme Technology and Green Synthesis Research Group, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. 3 Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia. 4 Forensic Science Programme, School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia. * email: aidarasyidah@utm.my; naji.arafat@utm.my