Communicating Particles: Identification Taggant and Temperature Recorder in One Single Supraparticle

Abstract

“Communicating particles” are reported that combine an identification (ID) taggant and a temperature recorder in one single entity—a micron‐scaled supraparticle. The optical information carriers within the hybrid inorganic‐organic supraparticles are three different types of luminescent nanoparticles, which can be read‐out using single‐wavelength excitation. These three nanoparticle types are assembled into a core‐satellite structure via a two‐step droplet evaporation technique. The core is built‐up from Tb3+ and Eu3+‐doped nanophosphors, providing an environmentally stable ID that is easily tunable through ratiometric spectral coding. This core is surrounded by organic, dye‐doped polymer nanoparticle satellites, acting as thermal‐history‐recorders of their environment. Exposed to a threshold temperature, the luminescence of the utilized 7‐diethylamino‐4‐methylcoumarin‐doped polymer nanoparticles is irreversibly quenched. This “turn‐off ” signal response is attributed to conformational changes in the dyes’ excited state and an alteration of their molecular environment, respectively, triggered by the polymer nanoparticles’ glass transition. Thus, the sensitivity of the temperature recorder can be configured over a wide temperature range by varying the dye‐hosting polymer. At the same time, the ID of the particle, stemming from its inorganic building blocks, stays unaffected, thus stable against thermal changes. The idea of communicating particles introduces a promising concept for smart additives.

Colorful Luminescent Magnetic Supraparticles: Expanding the Applicability, Information Capacity, and Security of Micrometer‐Scaled Identification Taggants by Dual‐Spectral Encoding

“…The cobalt-doped SPIONs were synthesized following the same procedure, but partial substitution of FeCl Synthesis of Polymer Nanocomposite Particles: Fluorescent (LBBs) and magnetic nanoparticle nanocomposite particles (MBBs) were synthesized via an emulsion-solvent evaporation method (Figure S1, Supporting Information) slightly modified from previous studies. [29,111,112] As signal carriers for the LBBs, stock solutions (1 mg mL −1 ) of C1 and RhB in chloroform and C6 in dichloromethane were used. For the MBBs, the prepared ferrofluids of SPIONs and Co-doped SPIONs were utilized as magnetic signal carriers.…”

“…[102] Therefore, the observed interaction may stem from cross-coupling of the LBBs (emission-reabsorption events). [28,29,121] Note that also the emission of LBB-blue and the absorption of LBB-green overlap. However, the overlap is smaller, leading to less pronounced cross-coupling.…”

“…excitation should be used. [22,23,28,29] Therefore, as luminescent building blocks (LBBs), PS nanocomposite particles doped with highly luminescent commercial dyes that emit light in the blue (7-diethylamnio-4-methylcoumarin, coumarin 1, LBB-blue), green (3-(2-benzothiazolyl)-7-(diethylamino)coumarin, coumarin 6, LBB-green), and red wavelength areas (rhodamine B, LBB-red) were selected (Figure 1e) to grant the necessary spectral separation (Figure S2, Supporting Information).…”

“…[8][9][10][11][12][13][14][15][16][17][18][19] Strategies that utilize designed physicochemical material properties for the spectral encoding of information have come to the forefront as they promise to achieve a plethora of encoding options and a high level of ID security. [20][21][22][23][24][25][26][27][28][29] Lately, optically resolved signals, including UV-vis, [30][31][32] infrared, [33][34][35] surface-enhanced Raman scattering (SERS), [36][37][38] and fluorescence, [22,23,27,28,[39][40][41][42][43][44][45][46][47][48][49][50][51][52]…”

“…[97] Among optomagnetic (nano)materials, the combination of magnetic and luminescent signal characteristics is especially attractive due to spectral, spatial, as well as time resolved readout options of the luminescence from a certain distance with often unmatched sensitivity. [29,98,99] Many of these innovative materials show great performance, albeit the true potential of the magnetic functionality in luminescent magnetic hybrid materials is not retrieved yet.…”