A novel bifunctional composite powder with moderate magnetic properties and intense fluorescence was prepared via a layer-by-layer assembly route. After the self-assembly procedure run up to 7 times, the as-prepared Fe₃O₄@SiO₂-CD(n) began to overcome the quenching effect from Fe₃O₄ nanoparticles and shown intense blue emission (λ_em = 434 nm) under 370 nm UV irradiation with a quantum yield of 45.04%. The morphological characterization revealed that it has a spherical and uniform core-shell structure of approximately 120 nm in diameter. The component analysis and contact angle test manifested the hydrophilic groups on the surface of the final products. As a result, this novel nanocomposite powder has two advantages over traditional fingerprint powder in both morphology/size and organic functional groups, which could provide more suitable physical adsorption and more chemical bonding in the interaction between fingerprint residues and powders. A series of fingerprint enhancement experiments and a novel quantitative evaluation both confirmed its high contrast, high sensitivity, and especially high selectivity over traditional methods for latent fingerprints. More importantly, in addition to its saturation magnetization of 6.4 emu/g, the abundant hydrophilic groups on the surface of our composite powder also played an important role in absorbing moisture in air and print residues to avoid powder dust from the user’s respiratory tract. Therefore, a fast, user-secure, and highly selective method was established and expected to be valuable in forensic science and related fields.

通过逐层组装的方法制备了具有适度磁性和强荧光的新型双功能复合粉末。自组装过程运行7次后，所制备的Fe ₃ O ₄ @SiO ₂ -CD（n）开始克服Fe ₃ O ₄纳米颗粒的猝灭作用，并显示出强烈的蓝色发射（_λem在370 nm的紫外线辐射下（= 434 nm），量子产率为45.04％。形态学特征表明其具有球形且均匀的直径约120nm的核-壳结构。成分分析和接触角测试显示了最终产品表面上的亲水基团。结果，这种新型的纳米复合粉末在形态/大小和有机官能团方面均比传统指纹粉具有两个优势，可以在指纹残基和粉末之间的相互作用中提供更合适的物理吸附和更多的化学键合。一系列指纹增强实验和新颖的定量评估均证实了其相对于传统的潜在指纹方法具有高对比度，高灵敏度以及特别高的选择性。更重要的是，除了其饱和磁化强度为6.4 emu / g外，我们复合粉体表面的丰富亲水基团在吸收空气中的水分和印刷残留物以防止粉尘从用户呼吸道中吸收方面也发挥了重要作用。因此，建立了一种快速，用户安全且高度选择性的方法，并有望在法医学和相关领域中有价值。