Photoluminescent Oxygeneous-Graphitic Carbon Nitride Nanodot-Incorporated Bioderived Hyperbranched Polyurethane Nanocomposite with Anticounterfeiting Attribute

Photoluminescent Self-Healable Waterborne Polyurethane/Mo and S Codoped Graphitic Carbon Nitride Nanocomposite with Bioimaging and Encryption Capability

Creating polymers that combine various functions within a single system expands the potential applications of such polymeric materials. However, achieving polymer materials that possess simultaneously elevated strength, toughness, and self-healing capabilities, along with special properties, remains a significant challenge. The present study demonstrates the preparation of S and Mo codoped graphitic carbon nitride (g-C3N4) (Mo@S-CN) nanohybrid and the fabrication of self-healing waterborne polyurethane (SHWPU)/Mo@S-CN (SHWPU/NS) nanocomposites for advanced applications. Mo@S-CN is an intriguing combination of g-C3N4 nanosheets and molybdenum oxide (MoOx) nanorods, forming a complex lamellar structure. This unique arrangement significantly improves the inborn properties of SHWPU to an impressive degree, especially mechanical strength (28.37-34.11 MPa), fracture toughness (73.65-140.98 MJ m-2), and thermal stability (340.17-348.01 °C), and introduces fluorescence activity into the matrix. Interestingly, a representative SHWPU/NS0.5 film is so tough that a dumbbell of 15 kg, which is 53,003 times heavier than the weight of the film, can be successfully lifted without any significant crack. Remarkably, fluorescence activity is developed because of electronic excitations occurring within the repeating polymeric tris-triazine units of the Mo@S-CN nanohybrid. This fascinating feature was effectively harnessed by assessing the usability of aqueous dispersions of the Mo@S-CN nanohybrid and photoluminescent SHWPU/NS nanocomposites as sustainable stains for bioimaging of human dermal fibroblast cells and anticounterfeiting materials, respectively. The in vitro fluorescence tagging test showed blue emission from 365 nm excitation, green emission from 470 nm excitation, and red emission from 545 nm excitation. Most importantly, in vitro hemocompatibility assessment, in vitro cytocompatibility, cell proliferation assessment, and cellular morphology assessment supported the biocompatibility nature of the Mo@S-CN nanohybrid and SHWPU/NS nanocomposites. Thus, these materials can be used for advanced applications including bioimaging.

Graphitic Carbon Nitride Quantum Dots (g-C3 N4 QDs): From Chemistry to Applications

Since their emergence in 2014, graphitic carbon nitride quantum dots (g-C3 N4 QDs) have attracted much interest from the scientific community due to their distinctive physicochemical features, including structural, morphological, electrochemical, and optoelectronic properties. Owing to their desirable characteristics, such as non-zero band gap, ability to be chemically functionalized or doped, possessing tunable properties, outstanding dispersibility in different media, and biocompatibility, g-C3 N4 QDs have shown promise for photocatalysis, energy devices, sensing, bioimaging, solar cells, optoelectronics, among other applications. As these fields are rapidly evolving, it is very strenuous to pinpoint the emerging challenges of the g-C3 N4 QDs development and application during the last decade, mainly due to the lack of critical reviews of the innovations in the g-C3 N4 QDs synthesis pathways and domains of application. Herein, an extensive survey is conducted on the g-C3 N4 QDs synthesis, characterization, and applications. Scenarios for the future development of g-C3 N4 QDs and their potential applications are highlighted and discussed in detail. The provided critical section suggests a myriad of opportunities for g-C3 N4 QDs, especially for their synthesis and functionalization, where a combination of eco-friendly/single step synthesis and chemical modification may be used to prepare g-C3 N4 QDs with, for example, enhanced photoluminescence and production yields.

Recent Advances in Carbon Nanodots: A Promising Nanomaterial for Biomedical Applications

Carbon nanodots (CNDs) are an emerging class of nanomaterials and have generated much interest in the field of biomedicine by way of unique properties, such as superior biocompatibility, stability, excellent photoluminescence, simple green synthesis, and easy surface modification. CNDs have been featured in a host of applications, including bioimaging, biosensing, and therapy. In this review, we summarize the latest research progress of CNDs and discuss key advances in our comprehension of CNDs and their potential as biomedical tools. We highlighted the recent developments in the understanding of the functional tailoring of CNDs by modifying dopants and surface molecules, which have yielded a deeper understanding of their antioxidant behavior and mechanisms of action. The increasing amount of in vitro research regarding CNDs has also spawned interest in in vivo practices. Chief among them, we discuss the emergence of research analyzing CNDs as useful therapeutic agents in various disease states. Each subject is debated with reflection on future studies that may further our grasp of CNDs.

Luminescent nanohybrid of ZnO quantum dot and cellulose nanocrystal as anti-counterfeiting ink

Luminescent quantum dot (QD) ink is currently a powerful tool for generating hidden information on paper substrates. Herein, we fabricated a nanohybrid ink of bacterial cellulose nanocrystal (BCNC) and UV-responsive ZnO QD via electrostatic self-assembly for improving solvent resistance and message encryption process. Under investigations on the printed areas, the nanohybrid can slightly infiltrate into the paper fibers and form a thin layer on the top of paper substrates, conferring an enhanced print permanence against wetting conditions while maintaining the daylight unobservability and its luminescent stability. The water resistance of the proposed nanohybrid ink enables developing a higher security level that the prints can be submerged in CuCl₂ aqueous solutions to quench the luminescent message. The concealed message can eventually be revealed under UV light again after submerging in EDTA solution. Our ZnO QD/BCNC nanohybrid with eco-friendly nature therefore exhibits great potential as security marking ink for counterfeit protection with sustainable uses.

Synthesis and Characterization of New Mesoporous Polyurethane-Nitrogen Doped Carbon Dot Nanocomposites: Ultrafast, Highly Selective and Sensitive Turn-off Fluorescent Sensors for Fe3+ Ions

A new fluorescent mesoporous polyurethane (PU) (9) was synthesized by reaction between 2,2'-(methylenebis(4,1-phenylene))bis(5-isocyanatoisoindoline-1,3-dione) (Diisocyanate) (5) and 4,4',4″-((1,3,5-triazine-2,4,6-triyl)tris (azanediyl))triphenol (Triol, TO) (8) (molar ratio 3:2). PU was characterized by using FT-IR, ¹H-NMR, XRD, UV-Vis, TGA, Nitrogen adsorption-desorption isotherm, BET, FE-SEM and Photoluminescence (PL) analyses. To the best of our knowledge, this is the first time that a fluorescent polyurethane has been made without the use of commercial fluorescent materials. PU has high fluorescent intensity and it is ultrafast (about few seconds), highly selective and sensitive turn-off fluorescent sensor for Fe³⁺ ions. This chemosensor exhibited a wide concentration range of (10-250)×10^-6 M Fe³⁺ with quenching efficiency (η) 97.50%. Limit of detection (LOD), limit of quantification (LOQ) and quenching constant (Ksv) values were calculated 10.10×10^-6 M, 30.60×10^-6 M and 6919.31 M^-1, respectively. Nitrogen doped carbon dots (N-doped CDs) as fluorescent nanoparticles and with the aim of improving Fe³⁺ detecting were synthesized by microwave-assisted and using citric acid monohydrate (10) and ethylenediamine (11) as carbon and nitrogen sources, respectively. Fluorescent nanocomposites (FNCs) were prepared by using casting and in-situ methods. In both methods, two nanocomposites containing 5 and 10%w of N-doped CDs were prepared. FNCs were characterized by using FT-IR, UV-Vis, XRD, TGA, Nitrogen adsorption-desorption isotherm, BET, FE-SEM and PL analyses. All nanocomposites showed better thermal property and sensitivity and lower LOD values in lower concentration of Fe³⁺ related to PU. Among them, FNC10in exhibited the best results as η, LOD, LOQ, Ksv reached 99.80%, 1.15×10^-6 M, 3.48×10^-6 M and 53,551.48 M^-1, respectively.