Carbon Dot Powders with Cross-Linking-Based Long-Wavelength Emission for Multicolor Imaging of Latent Fingerprints

Abstract

A simple and convenient preparation of multicolor carbon dot (CD) solutions was proposed using neutral red as the carbon and nitrogen sources by a layering and extraction procedure. After poly­(vinylpyrrolidone) (PVP) as the cross-linking agent was doped into as-prepared solutions, red-, orange-, and yellow-emitting CD powders were finally fabricated with solid-state fluorescence quantum (QY) yields of 6.33, 16.5, and 43.6%, respectively. Through studies of surface functional groups and photoluminescence (PL) property compared with solution and powder states of CDs, the cross-linking effect emission (CEE) brought by PVP was confirmed in charge of the high solid-state QY of CD powders. In addition, the conjugate structure of neutral red and increasing hydrophobicity are believed to be responsible for the long-wavelength emission of CD powders. Notably, multicolor imaging of latent fingerprints (LFPs) was successfully achieved on complex background surfaces under 365 nm UV illumination. As a result, these carbon-based phosphors are promising in forensic investigation, bioimaging, and sensing fields.

One-step facile preparation of carbon dots with high fluorescence quantum yield and application in rapid latent fingerprint detection

“…3a), which again indicated the presence of a disordered graphitic structure and formation of carbon dots. 24–27…”

“…3a), which again indicated the presence of a disordered graphitic structure and formation of carbon dots. [24][25][26][27] To determine the optical properties of GCDs and GCD-starch powder, the UV-Vis absorption spectra of starch, GCDs, and GCD-starch powder were compared, as shown in Fig. 3b.…”

Instantaneous High‐Resolution Visual Imaging of Latent Fingerprints in Water Using Color‐Tunable AIE Pincer Complexes

“…A number of fluorescent materials have been used, including organic fluorophores, [ 7 ] organometallics, [ 8 ] nanoparticles, [ 9 ] quantum dots, [ 2a,10 ] conjugated polymer [ 2b,11 ] as well as metal–organic frameworks. [ 1c,12 ] In particular, aggregation‐induced emission (AIE) materials [ 13 ] have shown great potential in the visualization of LFPs due to their strong fluorescence, easy functionalization, and intrinsic AIE characteristics.…”

Solid-Phase Synthesis of Red Fluorescent Carbon Dots for the Dual-Mode Detection of Hexavalent Chromium and Cell Imaging

“…Specially, red fluorescence CDs (R-CDs) possess unique advantages for bioimaging and biosensing application, which can effectively eliminate the interference of background fluorescence from biological tissue [ 22 ]. However, current R-CDs still suffer from low photoluminescence efficiency and product yield, and the synthesis of them also usually cannot remove their dependence on organic solvent and inorganic acid [ 23 , 24 , 25 , 26 ]. The solid-phase synthesis method was advocated for in the preparation of CDs to overcome the deficiencies of traditional solvothermal and microwave methods because of its simplicity, solvent-free, easy operation and repetition.…”