The synthesis of newly modified CdTe quantum dots and their application for improvement of latent fingerprint detection

Motivated by the urgent demand for the detection of latent fingerprints using fluorescence-based nanotechnology, this work was devoted to developing a simple synthetic approach to obtain positively charged CdTe QDs with enhanced fluorescence and affinity for the improvement of latent fingerprint detection. Through this synthetic method, the positively charged CdTe-COONH3NH3+ QDs were successfully achieved by using hydrazine hydrate as both the surface stabilizer and pH adjuster during the preparation process. In comparison to the negatively charged CdTe-COO-QDs prepared by using sodium hydroxide as the pH adjuster, the CdTe-COONH3NH3+ QDs showed enhanced fluorescence. The effectiveness of CdTe-COO- and CdTe-COONH3NH3+ QDs for detection of latent fingerprints present on a large variety of smooth objects was systematically and comparatively studied. The results indicate that the detection of latent fingerprints by using CdTe-COONH3NH3+ QDs as fluorescent labeling marks was greatly enhanced, and more characteristic finger ridge details were detected and identified due to their enhanced affinity with latent fingerprints, in comparison to the detection by using CdTe-COO-QDs as fluorescent labeling marks. The CdTe-COONH3NH3+ QDs show superior detection capability than the CdTe-COO-QDs, which greatly improves the applicability of CdTe QDs for practical application in latent fingerprint detection.