Cadmium-free quantum dots in aqueous solution: Potential for fingermark detection, synthesis and an application to the detection of fingermarks in blood on non-porous surfaces

Abstract

The use of quantum dots (QDs) in the area of fingermark detection is currently receiving a lot of attention in the forensic literature. Most of the research efforts have been devoted to cadmium telluride (CdTe) quantum dots often applied as powders to the surfaces of interests.Both the use of cadmium and the nano size of these particles raise important issues in terms of health and safety. This paper proposes to replace CdTe QDs by zinc sulphide QDs doped with copper (ZnS:Cu) to address these issues. Zinc sulphide-copper doped QDs were successfully synthesized, characterized in terms of size and optical properties and optimized to be applied for the detection of impressions left in blood, where CdTe QDs proved to be efficient. Effectiveness of detection was assessed in comparison with CdTe QDs and Acid Yellow 7(AY7, an effective blood reagent), using two series of depletive blood fingermarks from four donors prepared on four non-porous substrates, i.e. glass, transparent polypropylene, black polyethylene and aluminium foil. The marks were cut in half and processed separately with both reagents, leading to two comparison series (ZnS:Cu vs. CdTe, and ZnS:Cu vs. AY7).ZnS:Cu proved to be better than AY7 and at least as efficient as CdTe on most substrates.Consequently, copper-doped ZnS QDs constitute a valid substitute for cadmium-based QDs to detect blood marks on non-porous substrates and offer a safer alternative for routine use.

Fluorescent Nanomaterials for the Development of Latent Fingerprints in Forensic Sciences

“…[62] The developing mechanisms and procedures were quite similar to that reported by Becue et al in 2009. [61] In addition, both AY 7- and TGA-modified CdTe QDs (as reported by Becue et al [57] in 2009) were used to develop the blood fingerprints for comparison.…”

Nanoparticles used for fingermark detection—A comprehensive review

“…This is most certainly due to the availability and relative ease of synthesis of those compounds. Besides uncommon types of QDs such as boron carbon oxynitride (Jia et al, ), CdSSe (Algarra et al, ), and Cu 7 S 4 (Cui et al, ), it is worth mentioning the use of ZnSe (Ryu, Jung, & Lee, ) and ZnS (Cheng et al, ; S. Moret, Bécue, & Champod, ; C. Xu et al, ) that attracted attention in an endeavor to avoid the use of cadmium‐based QDs for obvious health and safety concerns. It is worth mentioning that none of the infrared fluorescence‐emitting QDs have been used for fingermark detection.…”

“…The other 15 publications all involving the use of water‐soluble QDs, with a majority being cadmium‐based particles, either CdTe (Bécue, Moret, Champod, & Margot, ; Cai, Yang, Wang, Yu, & Liu, ; Cheng, Ajimo, & Chen, ; F. Gao et al, ; Y. Li, Xu, Shu, Hou, & Wu, ; J. Liu, Shi, Yu, Yang, & Zuo, ; Shen et al, ; R. Yang, Wang, Xia, Wang, & Liu, ; Yu et al, ) or CdSe (Menzel, ; Y. F. Wang et al, ; Y. F. Wang, Yang, Wang, Shi, & Liu, ). Only one type of noncadmium‐based QDs was reported (ZnS) (Cheng, Aijmo, et al, ; S. Moret et al, ; C. Xu, Zhou, et al, ).…”

“…Aside from cadmium‐based QDs, several groups endeavored to provide nontoxic NPs alternatives using ZnS (Cheng, Aijmo, et al, ; S. Moret et al, ; C. Xu, Zhou, et al, ). Carboxyl groups were used to functionalize the NPs; sebaceous‐rich (Cheng, Aijmo, et al, ) and blood (S. Moret et al, ) fingermarks were successfully detected on aluminum, glass, and plastic. S. Moret et al () showed that ZnS QDs were a valid alternative to CdTe QDs.…”

“…This is most certainly due to the availability and relative ease of synthesis of those compounds. Besides uncommon types of QDs such as boron carbon oxynitride (Jia et al, 2018), CdSSe (Algarra et al, 2013), and Cu 7 S 4 (Cui et al, 2015), it is worth mentioning the use of ZnSe (Ryu, Jung, & Lee, 2015) and ZnS S. Moret, Bécue, & Champod, 2013;C.…”