Hybrid Inorganic–Organic Luminescent Supraparticle Taggants with Switchable Dual‐Level ID

Abstract

Tracking and tracing of objects are of paramount importance for realizing a Circular Economy and can be achieved by incorporating micrometer‐scaled luminescent identification (ID) taggants. While established systems are passive, displaying merely an ID feature, for monitoring a products’ life cycle, conscious taggants with stimuli‐triggered switchable ID signals, e.g., to record a recycling step, are desired. Herein, micrometer‐scaled hybrid inorganic–organic taggants with a temperature‐triggered switchable luminescent ID are reported. They are produced by assembling eight different types of organic and inorganic nanoparticles (NPs) via a two‐step spray‐drying process into supraparticles (SPs) with a core–shell structure. This hierarchical structure and well‐balanced mass‐ratios of the utilized nanosized building blocks are key to controlling the occurring coupling effects within SPs, thus, to obtain the switchable ID functionality. Initially, the temperature‐inert inorganic luminescent ID‐level, located in the core, is concealed by a mutable organic ID‐level, emitted by the shell. Upon specific heat treatment, the ID is switched by irreversible quenching of the organic ID‐level, revealing the inorganic ID‐level. Furthermore, both ID‐levels are read out ratiometrically using the same excitation wavelength for their detection. Based on the SPs’ toolbox‐like manufacturing, the ID signals are adjustable to yield the demanded code variety on both ID‐levels.

Modulating the Microenvironment of Coumarin Dyes within Multihierarchical Supraparticles: En Route toward Versatile Luminescent Dual‐Threshold Temperature Indicators with Ratiometric Readout

“…This processing step introduces the first level of hierarchy to the final SPs. In previous studies, [23,27,34] we exploited a versatile synthetic approach to incorporate hydrophobic coumarin dyes into thermoplastic polymer NPs via an emulsionsolvent evaporation approach utilizing sodium dodecyl sulfate (SDS) as a surfactant (schematic depiction, Figure S1, Supporting Information). [35] This approach offers an almost free choice of dye type, dye concentration, and polymer type.…”

Communicating Supraparticles to Enable Perceptual, Information‐Providing Matter

“…Pioneering examples showed that it is likely possible to control the interaction of signal carriers by assembling them into appropriate SP architectures. [54,94,95,170,173] Whether this level of interaction control can also be achieved for CSPs is, however, an open research question, which requires an in-depth investigation. If an all-rounder method to assemble all selected building blocks into CSPs with an appropriate architecture cannot be identified, combinations of different, consecutively conducted assembly methods could be exploited.…”

“…As another option, some pioneering strategies to reprogram the ID signature of a tag using external triggers without the need to extract the integrated CSPs have been described. [151,170] To realize this vision in its entirety, including the reactivation of the recorder features, however, many additional innovation cycles are required. If CSPs can neither be recovered nor reprogrammed, they should be deactivated upon exposure to specific external triggers to thereby pave the way toward fresh tagging with customized CSPs for the second use of the material.…”

“…Alternatively, the distribution of signal carriers can be altered by the addition of nonsignal-carrying, environmentally robust, NPs, e.g., SiO 2 NPs, and their utilization as spacers (Figure 5a4). [54,114,170,171] Such an architecture reduces the interplay between interacting species by increasing their distances. Another strategy to reduce the interaction of all signal-carrying building blocks is the encapsulation of individual or soft-agglomerated signal carrier types into, for instance, polymer NPs and their subsequent assembly into multihierarchical SP architectures (Figure 5a5).…”

Rising Like a Phoenix from the Ashes: Fire‐Proof Magnetically Retrievable Supraparticles with an Optical Fingerprint for Postmortem Identification of Products

“…[16][17][18][19][20][21][22][23] These spectral markers are promising for the development of postmortem identification (ID) tags, assuming their code-giving physical properties can withstand the harsh conditions of a fire event. [24][25][26][27] However, this is not the case for the vast majority of marking technologies relying on organic [24,[28][29][30][31][32][33][34][35] or metallic materials [22,[36][37][38][39] that either decompose or oxidize under fire conditions and lose their signaling properties. Previous work supports the assumption that inorganic Ln 3+ doped hydroxyapatite (HAp) nanowires are fire resistant.…”