Abstract：Latent fingerprints (LFs) are commonly encountered at crime scenes. Developing the LFs clearly is the precondition for further analysis and identification. In this work, titanium dioxide-coated carbon dots (CDs@TiO2) fluorescent nanosuspensions were prepared and used for high-quality LF development. Firstly, carbon dots (CDs) were synthesized via a solvothermal approach using citric acid and urea as raw materials and N,N-dimethylformamide as solvent. Then, CDs@TiO2 nanomaterials (NMs) were formed by coating CDs with a layer of TiO2 shell based on the ammonia-catalyzed hydrolysis of titanium butoxide, and the synthesis conditions were optimized. The optimized synthesis conditions were as follows: the amount of CDs, tetrabutyl orthotitanate, water, and ammonium hydroxide was 3.0, 1.5, 1.5, and 0.1 mL, respectively, the reaction temperature was 50 ℃, and the dropping period was 30 min. After that, the morphology, composition, structure, and optics properties of CDs and CDs@TiO2 NMs were characterized. Characterization results showed that, CDs were near spherical with an average diameter of 7.54 nm, they could give characteristic Raman scattering peaks as well as infrared absorption peaks of CDs, and possessed the crystal structure of hexagonal graphite, their UV absorption peak was at 343 nm, and their maximum fluorescence excitation and emission wavelength was at 450 and 567 nm respectively; CDs@TiO2 were irregularly spherical with an average diameter of 114.85 nm, they could give characteristic Raman scattering peaks as well as infrared absorption peaks of both CDs and TiO2, and possessed the crystal structure of both hexagonal graphite and tetragonal rutile TiO2, their UV absorption peak was at 321 nm, and their maximum fluorescence excitation and emission wavelength was at 387 and 529 nm respectively. Finally, CDs@TiO2 NMs were made into nanosuspension for developing LFs via hydrophobic interaction. The development conditions were optimized, and the results of LF development were investigated in detail. The optimized development conditions were as follows: the concentration of sodium dodecyl sulfate and choline chloride was 1.0‰~2.0‰ and 4.0‰~6.0‰ respectively, and the developing time period was 10~20 s. Experimental results showed that, the LFs could emit bright blue fluorescence under 490 nm excitation, which exhibited coherent and clear papillate ridges and distinct minutiae. Our proposed method based on CDs@TiO2 fluorescent nanosuspensions could develop the LFs on common smooth and non-porous substrates with high quality, possessing enough contrast, high sensitivity, good selectivity, and wide applicability.
马榕蔚，王 猛，李 杰，徐致泽，李 明，袁传军. 二氧化钛包覆碳点的合成、表征及手印显现应用研究[J]. 光谱学与光谱分析, 2025, 45(05): 1325-1333.
MA Rong-wei, WANG Meng, LI Jie, XU Zhi-ze, LI Ming, YUAN Chuan-jun. Synthesis and Characterization of Titanium Dioxide Coated Carbon Dots and Their Applications in Fingerprint Development. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2025, 45(05): 1325-1333.
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