Orthogonal Reconstruction of Upconversion and Holographic Images for Anticounterfeiting Based on Energy Transfer

Algorithm in chemistry: molecular logic gate-based data protection

Data security is crucial for safeguarding the integrity, authenticity, and confidentiality of documents, currency, merchant labels, and other paper-based assets, which sequentially has a profound impact on personal privacy and even national security. High-security-level logic data protection paradigms are typically limited to software (digital circuits) and rarely applied to physical devices using stimuli-responsive materials (SRMs). The main reason is that most SRMs lack programmable and controllable switching behaviors. Traditional SRMs usually produce static, singular, and highly predictable signals in response to stimuli, restricting them to simple "BUFFER" or "INVERT" logic operations with a low security level. However, recent advancements in SRMs have collectively enabled dynamic, multidimensional, and less predictable output signals under external stimuli. This breakthrough paves the way for sophisticated encryption and anti-counterfeiting hardware based on SRMs with complicated logic operations and algorithms. This review focuses on SRM-based data protection, emphasizing the integration of intricate logic and algorithms in SRM-constructed hardware, rather than chemical or material structural evolutions. It also discusses current challenges and explores the future directions of the field-such as combining SRMs with artificial intelligence (AI). This review fills a gap in the existing literature and represents a pioneering step into the uncharted territory of SRM-based encryption and anti-counterfeiting technologies.

"All-in-One Functionalization and Synergic Ordering" Strategy Enables Multimode Anti-Counterfeiting Patterns

Conventional multimode anticounterfeiting systems usually suffer high cost, complicated structures, and different optical channel interferences. In this study, we demonstrate a simple strategy named "all-in-one functionalization and synergic ordering" to prepare quadruple mode patterns on a photoresponsive alternating copolymer P(DPA-alt-BP) film. Herein, a 9,10-diphenylanthracene (DPA) nonanoate unit serves as the multipurpose moiety with photoresponse and fluorescence, performing photodimerization upon 365 nm UV irradiation. The liquid crystal mesogen biphenyl (BP) caproate units can orderly align along strain for polarized sight and improve the microphase separation. Upon UV irradiation through a photomask followed by solvent annealing, the P(DPA-alt-BP) film is first gradient-cross-linked and then undergoes stress relief and microphase separation, giving rise to a synergic ordering effect that enables fabrication of an anticounterfeiting pattern with quadruple modes, i.e., wrinkled pattern, substructure on a wrinkled surface, distinguishable fluorescent emission, and polarized sight on the film. This strategy is promising for high-level anticounterfeiting applications and provides helpful inspiration to the development of innovative photoresponsive materials.

Advanced Anticounterfeiting: Angle-Dependent Structural Color-Based CuO/ZnO Nanopatterns with Deep Neural Network Supervised Learning

Current anticounterfeiting technologies rely on deterministic processes that are easily replicable, require specialized devices for authentication, and involve complex manufacturing, resulting in high costs and limited scalability. This study presents a low-cost, mass-producible structural color-based anticounterfeiting pattern and a simple algorithm for discrimination. Nanopatterns aligned with the direction of incident light were fabricated by electrospinning, while CuO and ZnO were grown independently through a solution process. CuO acts as a reflective layer, imparting an angle-dependent color dependence, while ZnO allows the structural color to be tuned by controlling the hydrothermal synthesis time. The inherent randomness of electrospinning enables the creation of unclonable patterns, providing a robust anticounterfeiting solution. The fabricated CuO/ZnO nanopatterns exhibit strong angular color dependence and are capable of encoding high-density information. It uses deep learning algorithms to achieve an average discrimination accuracy of 94%, with a streamlined computational structure based on shape and color features to achieve a processing speed of 80 ms per sample. The training images are acquired with standard high-resolution cameras, ensuring accessibility and practicality. This approach offers an efficient and scalable next-generation solution for anticounterfeiting applications, including documents, currency, and brand labels.

Orthogonal upconversion nanocarriers for combined photodynamic therapy and precisely triggered gene silencing in combating keloids

Keloids are pathological scars characterized by excessive fibroblast proliferation, abnormal collagen deposition, and chronic inflammation, which often result in high recurrence rates and limited treatment success. Targeting BACH1 with gene therapy has shown promise in regulating fibroblast activity and reducing inflammation. However, effective delivery systems for targeted gene therapy in keloids remain a major challenge. Here, we develop a novel nanocarrier platform based on orthogonal upconversion nanoparticles (OUNCs) to achieve spatiotemporal silencing of BACH1 and combined photodynamic therapy (PDT). The OUNCs are composed of orthogonal upconversion nanoparticles (UCNPs), photosensitizer (Rose Bengal), ROS-sensitive diselenide bonds (SeSe), therapeutic siBACH1, and an active targeting moiety (hyaluronic acid) to specifically target keloid fibroblasts (KFs). We demonstrate that the OUNCs can effectively induce KFs apoptosis, inhibit KFs proliferation, and reduce M2 macrophages recruitment by modulating the Rap1/MEK/ERK signaling pathway. Our study represents a breakthrough in precision therapy for keloids, providing a promising platform that integrates siBACH1-based gene therapy with NIR light-triggered PDT.

Energy Aggregation for Illuminating Upconversion Multicolor Emission Based on Ho3+ Ions

Lanthanide-doped upconversion luminescent nanoparticles (UCNPs) have garnered extensive attention due to their notable anti-Stokes shifts and superior photostability. Notably, Ho3+-based UCNPs present a complex energy level configuration, which poses challenges in augmenting their luminescence efficiency. Herein, a rational design strategy was used to enhance the upconversion luminescence intensity of Ho3+ ions by improving the photon absorption ability and energy utilization efficiency. Efficient absorption and transfer of excitation light energy were achieved through carefully selected host materials, precisely controlled sensitizers, and the design of external energy antennas using organic dyes, enhancing upconversion luminescence. Due to the attenuation effect of hydroxyl vibration on upconversion luminescence, the nanomaterials exhibit multicolor luminescent characteristics in different solution environments. Significantly, the composites exhibit intense upconversion of red light in aqueous solution, showing great application potential in biomedicine and colorimetry.

Towards core-shell engineering for efficient luminescence and temperature sensing

Research on the core-shell design of rare earth-doped nanoparticles has recently gained significant attention, particularly in exploring the synergistic effects of combining active and inert shell layers. In this study, we successfully synthesized 8 types of spherical core-shell Na-based nanoparticles to enhance the efficiency of core-shell design in upconversion luminescence and temperature sensing through the strategic arrangement of inert and active layers. The most effective upconversion luminescence was observed under 980 nm and 808 nm laser excitation using NaYF4 inert shell NaYF4:Yb3+, Er3+@ NaYF4 and NaYF4@ NaYF4:Yb3+, Nd3+ core-shell nanostructures. Moreover, the incorporation of the NaYbF4 active shell structure led to a significant increase in relative sensitivity in ratio luminescence thermometry. Notably, the NaYF4:Yb3+, Nd3+, Er3+@ NaYbF4 core-shell structure demonstrated the highest relative sensitivity of 1.12 %K-1. This research underscores the crucial role of inert shell layers in enhancing upconversion luminescence in core-shell structure design, while active layers play a key role in achieving high-sensitivity temperature detection capabilities.

Tm3+ mediated multicolor luminescence of NaYbF4:Er,Tm@NaYF4 for advanced anti-counterfeiting

Lanthanide doped multicolor luminescent materials have attracted extensive attention due to their advanced anti-counterfeiting properties. However, designing a simple, hard-to-copy and multicolor anti-counterfeiting strategy based on upconversion nanoparticles (UCNPs) remains a huge challenge. Herein, a strategy to modulate luminescence color by altering the mediating action of Tm3+ was proposed. As a proof of concept, the mediating action of Tm3+ was explored in NaYbF4:30%Er,1%Tm@NaYF4 by changing the doping ratio of Yb3+/Er3+/Tm3+, and red, yellow and blue luminescence was successfully obtained. Then, NaYbF4:x%Er,1%Tm@NaYF4 (x = 2, 10, 30, 50, 99), NaYbF4:x%Er@NaYF4 (x = 2, 10, 30, 50, 100) and NaYbF4:1%Tm@NaYF4:x%Er@NaYF4 (x = 2, 10, 30, 50, 100) were synthesized to further identify that the mediating action of Tm3+ was related to the doping ratio and distance between dopant ions. In addition, the luminescence color of NaYbF4:30%Er,1%Tm@NaYF4 changed from red to yellow with the increase of excitation power density. Based on the above, NaYbF4:Er,Tm@NaYF4 UCNPs show excellent performance in anti-counterfeiting of paintings, thus revealing their great potential in advanced anti-counterfeiting applications.

Stimulus-responsive polymer materials toward multi-mode and multi-level information anti-counterfeiting: recent advances and future challenges

Information storage and security is one of the perennial hot issues in society, while the further advancements of related chemical anti-counterfeiting systems remain a formidable challenge. As emerging anti-counterfeiting materials, stimulus-responsive polymers (SRPs) have attracted extensive attention due to their unique stimulus-responsiveness and charming discoloration performance. At the same time, single-channel decryption technology with low-security levels has been unable to effectively prevent information from being stolen or mimicked. As a result, it would be of great significance to develop SRPs with multi-mode and multi-level anti-counterfeiting characteristics. This study summarizes the latest achievements in advance anti-counterfeiting strategies based on SRPs, including multi-mode anti-counterfeiting (static information) and multi-level anti-counterfeiting (dynamic information). In addition, the promising applications of such materials in anti-counterfeiting labels, identification platforms, intelligent displays, and others are briefly reviewed. Finally, the challenges and opportunities in this emerging field are discussed. This review serves as a useful resource for manipulating SRP-based anti-counterfeiting materials and creating cutting-edge information security and encryption systems.

Integrating biopolymer design with physical unclonable functions for anticounterfeiting and product traceability in agriculture

Smallholder farmers and manufacturers in the Agri-Food sector face substantial challenges because of increasing circulation of counterfeit products (e.g., seeds), for which current countermeasures are implemented mainly at the secondary packaging level, and are generally vulnerable because of limited security guarantees. Here, by integrating biopolymer design with physical unclonable functions (PUFs), we propose a cryptographic protocol for seed authentication using biodegradable and miniaturized PUF tags made of silk microparticles. By simply drop casting a mixture of variant silk microparticles on a seed surface, tamper-evident PUF tags can be seamlessly fabricated on a variety of seeds, where the unclonability comes from the stochastic assembly of spectrally and visually distinct silk microparticles in the tag. Unique, reproducible, and unpredictable PUF codes are generated from both Raman mapping and microscopy imaging of the silk tags. Together, the proposed technology offers a highly secure solution for anticounterfeiting and product traceability in agriculture.

Lanthanide-Doped Upconversion Nanoparticles: Exploring A Treasure Trove of NIR-Mediated Emerging Applications

Lanthanide-doped upconversion nanoparticles (UCNPs) possess the remarkable ability to convert multiple near-infrared (NIR) photons into higher energy ultraviolet-visible (UV-vis) photons, making them a prime candidate for several advanced applications within the realm of nanotechnology. Compared to traditional organic fluorophores and quantum dots (QDs), UCNPs possess narrower emission bands (fwhm of 10-50 nm), large anti-Stokes shifts, low toxicity, high chemical stability, and resistance to photobleaching and blinking. In addition, unlike UV-vis excitation, NIR excitation is nondestructive at lower power intensities and has high tissue penetration depths (up to 2 mm) with low autofluorescence and scattering. Together, these properties make UCNPs exceedingly favored for advanced bioanalytical and theranostic applications, where these systems have been well-explored. UCNPs are also well-suited for bioimaging, optically modulating chemistries, forensic science, and other state-of-the-art research applications. In this review, an up-to-date account of emerging applications in UCNP research, beyond bioanalytical and theranostics, are presented including optogenetics, super-resolution imaging, encoded barcodes, fingerprinting, NIR vision, UCNP-assisted photochemical manipulations, optical tweezers, 3D printing, lasing, NIR-II imaging, UCNP-molecule nanohybrids, and UCNP-based persistent luminescent nanocrystals.

Invisible Thermoplasmonic Indium Tin Oxide Nanoparticle Ink for Anti-counterfeiting Applications

In this study, we present a thermoplasmonic transparent ink based on a colloidal dispersion of indium tin oxide (ITO) nanoparticles, which can offer several advantages as anti-counterfeiting technology. The custom ink could be directly printed on several substrates, and it is transparent under visible light but is able to generate heat by absorption of NIR radiation. Dynamic temperature mapping of the printed motifs was performed by using a thermal camera while irradiating the samples with an IR lamp. The printed samples presented fine features (in the order of 75 μm) and high thermal resolution (of about 250 μm). The findings are supported by thermal finite-element simulations, which also allow us to explore the effect of different substrate characteristics on the thermal readout. Finally, we built a demonstrator comprising a QR Code invisible to the naked eye, which became visible in thermal images under NIR radiation. The high transparency of the printed ink and the high speed of the thermal reading (figures appear/disappear in less than 1 s) offer an extremely promising strategy toward low-cost, scalable production of photothermally active invisible labels.

Nanocomposites based on lanthanide-doped upconversion nanoparticles: diverse designs and applications

Lanthanide-doped upconversion nanoparticles (UCNPs) have aroused extraordinary interest due to the unique physical and chemical properties. Combining UCNPs with other functional materials to construct nanocomposites and achieve synergistic effect abound recently, and the resulting nanocomposites have shown great potentials in various fields based on the specific design and components. This review presents a summary of diverse designs and synthesis strategies of UCNPs-based nanocomposites, including self-assembly, in-situ growth and epitaxial growth, as well as the emerging applications in bioimaging, cancer treatments, anti-counterfeiting, and photocatalytic fields. We then discuss the challenges, opportunities, and development tendency for developing UCNPs-based nanocomposites.

Upconversion/Downshifting Multimode Luminescence of Lanthanide-doped Nanocrystals for Multidimensional Information Encoding Security

Information encoding security has always been a research hotspot in the optical field. Although many studies focused on luminescent materials and techniques for information security, the optical information encoding is limited by low information capacity and security. Herein, we present new core-shell-shell (CSS) lanthanide-doped nanocrystals which display multi-stimuli-responsive and multimode emission. In the designed CSS nanostructure, the Stokes and anti-Stokes processes can be both achieved in the same nanocrystals under the excitation of 1532, 980, and 254 nm via self-excited Er³⁺ and Ce³⁺ -sensitized mechanisms. Subsequently, a group of unique multimode emission CSS nanocrystals were designed as optical modules and successfully utilized in multidimensional information encoding, which demonstrates high-level information encoding capability and security. This work brings a powerful idea for information encoding security designs based on multimode luminesce materials.

Tuning Luminescence of Lanthanide-Doped Upconversion Nanoparticles through Simultaneous Binary Cation Exchange

Dual-mode luminescent nanomaterials have outstanding performance in biosensing and multistage anticounterfeiting. Herein, we report the tuning of optical attributes of lanthanide-doped nanoparticles (NPs) via simultaneous binary cation exchange. We show that cation exchange of NaYF₄:Yb/Er (18/2 mol %)@NaLnF₄ (Ln = Y and Gd) NPs with a combination of Ce³⁺ and Tb³⁺ enables the resultant nanoparticles to exhibit both upconversion and downshifting emissions upon excitation at 980 and 254 nm, respectively. We find that in addition to introducing downshifting emission attributes, the use of Tb³⁺ ions allows conservation of the integrity of the parent core@shell NPs by decreasing the dissociation tendency caused by Ce³⁺ ions during the cation exchange. The upconversion color output can be tuned from green to red and blue by changing lanthanide combinations in the core NPs. This work not only provides an effective strategy for the optical tuning of lanthanide-doped NPs but also builds a platform for probing the difference in the reactivity nature of lanthanides.

Development of highly sensitive metal-ion chemosensor and key-lock anticounterfeiting technology based on oxazolidine

Optical chemosensors and ionochromic cellulosic papers based on oxazolidine chromophores were developed for selective photosensing of metal ions and information encryption as security tags, respectively. The oxazolidine molecules have been displayed highly intense fluorescent emission and coloration characteristics that are usable in sensing and anticounterfeiting applications. Obtained results indicated that oxazolidine molecules can be used for selective detection of pb²⁺ (0.01 M), and photosensing of Fe³⁺, Co²⁺ and Ag⁺ metal ion solutions by colorimetric and fluorometric mechanisms with higher intensity and sensitivity. Also, oxazolidine derivatives were coated on cellulosic papers via layer-by-layer method to prepare ionochromic papers. Prepared ionochromic papers were used for printing and handwriting of optical security tags by using of metal ion solutions as a new class of anticounterfeiting inks with dual-mode fluorometric and colorimetric securities. The ionochromic cellulosic papers can be used for photodetection of metal ions in a fast and facile manner that presence of metal ions is detectable by naked eyes. Also, key-lock anticounterfeiting technology based on ionochromic papers and metal ion solution as ink is the most significant strategy for encryption of information to optical tags with higher security.

Acenaphthoquinoxaline Derivatives as Dental Photoinitiators of Acrylates Polymerization

A series of dyes based on the acenaphthoquinoxaline skeleton was synthesized. Their structure was modified by introducing electron-withdrawing and electron-donating groups, increasing the number of conjugated double bonds and the number and position of nitrogen atoms, as well as the arrangement of aromatic rings (linear or angular). The dyes were investigated as a component in the photoinitiating systems of radical polymerization for a potential application in dentistry. They acted as the primary absorber of visible light and the acceptor of an electron, which was generated from a second component being an electron donor. Thus, the radicals were generated by the photoinduced intermolecular electron transfer (PET) process. Electron donors used differed in the type of heteroatom, i.e., O, S and N and the number and position of methoxy substituents. To test the ability to initiate the polymerization reaction by photoinduced hydrogen atom transfer, we used 2-mercaptobenzoxazole as a co-initiator. The effectiveness of the photoinitiating systems clearly depends on both the modified acenaphthoquinocaline structure and the type of co-initiator. The lower amount of heat released during the chain reaction and the polymerization rate comparable to this achieved for the photoinitiator traditionally used in dentistry (camphorquinone) indicates that the studied dyes may be valuable in this field.