Synthesis of CdTe quantum dots coated with biocompatible materials and investigation of their identification Properties

Fingerprint identification or dactyloscopy is a method for human identification. The impressions left by a human finger on surfaces are not visible to naked eyes (latent fingerprint); therefore, they require revelation to become visible and identified. Within the last century, several fingerprint revelation techniques such as optical, physical, and chemical were studied. These traditional methods have some shortcomings including hurting and destroying finger prints, long time of the revelation process and toxicity. Therefore, utilizing fluorescent quantum dot nanoparticles is under study due to their unique optical and chemical properties in fingerprint identification. In this article, the synthesis of cadmium telluride quantum dots is discussed, as they have a wide absorption spectrum, proper optical stability, greater radiation intensity, as well as high quantum efficiency, and their radiation is adjustable by composition and the size of the particles. The aim is to identify the effect of latent fingerprint on a variety of porous surfaces such as fabrics and papers or non-porous surfaces such as ceramics, glass and metals, with rapid detection with high contrast, sensitivity and selectivity and low toxicity. The synthesis method consists of using aqueous solution with Cadmium chloride and Tellurium dioxide with an alkaline pH solution. Studying photoluminescence in 540 nanometer wavelength, showed that the maximum radiation intensity is about 751, for 15 min. synthesis time. To modify and decrease toxicity a biocompatible coating (TEOS) was applied using the Stober method. Essentially, a silica layer reduced the photoluminescence by about 25%.