Tetrahedraphene: A Csp3 -centered 3D Molecular Nanographene Showing Aggregation-Induced Emission

Aggregation-induced emission silence-mediated pathogen detection using a rapidly degradable nanographene-embedded polymersome

Typical pathogen detection processes are time-consuming and require expensive equipment and professional operators, limiting their practical applicability. Developing a rapid and easy-to-read method of accurately sensing pathogenic bacteria is critical for reducing the spread and risk of infection in high-risk areas. Herein, the synthesis of nanographene (nanoG) that exhibits aggregation-induced emission (AIE) is described. The nanoG was embedded into a hydrophobic shell of poly(lactic-co-glycolic acid) (PLGA) polymersome in a double-emulsion process, significantly enhancing the nanoG luminescence under irradiation at 330 nm due to the enrichment of nanoG between the inner and outer PLGA shells. Both Gram-positive and Gram-negative bacteria can rapidly degrade the PLGA vesicular structure, leading to dispersal of the nanoG inside the shell and silencing the AIE effect. A linear relationship between the bacterial concentration and emissivity was established, and the detection limit was identified. Moreover, the polymersome has excellent selectivity for methicillin-resistant Staphylococcus aureus (MRSA) detection after a screening pretreatment of a bacterial mixture with suitable antibiotics. The AIE silencing could be observed with the naked eye in an MRSA-infected wound treated with the polymersome after 1 h of incubation, demonstrating a high potential for clinical rapid screening applications.

Multi-heteroatom doped nanographenes: enhancing photosensitization capacity by forming an electron donor-acceptor architecture

Systematically tuning and optimizing the properties of synthetic nanographenes (NGs) is particularly important for NG applications in diverse areas. Herein, by devising novel electron donor-acceptor (D-A) type structures, we reported a series of multi-heteroatom-doped NGs possessing an electron-rich chalcogen and electron-deficient pyrimidine or pyrimidinium rings. Comprehensive experimental and theoretical investigations revealed significantly different physical, optical, and energetic properties compared to the non-doped HBC or chalcogen-doped, non-D-A analogues. Some intriguing properties of the new NGs such as unique electrostatically oriented molecular stacking, red-shifted optical spectra, solvatochromism, and enhanced triplet excitons were observed due to the formation of the D-A electron pattern. More importantly, these D-A type structures can serve as photosensitizers to generate efficiently reactive-oxygen species (ROS), and the structure-related photosensitization capacity that strengthens the electron transfer (ET) process leads to significantly enhanced ROS which was revealed by experimental and calculated studies. As a result, the cell-based photodynamic therapy (PDT) indicated that the cationic NG 1-Me+ is a robust photosensitizer with excellent water-solubility and biocompatibility.

Intermediate Color Emission via Nanographenes with Organic Fluorophores

Photoluminescence (PL) color can be tuned by mixing fluorophores emitting the three primary colors in an appropriate ratio. When color tuning is achieved on a single substrate, we can simplify device structures. We demonstrated that nanographenes (NGs), which are graphene fragments with a size of tens of nanometers, could be utilized as carriers of fluorophores. The addition of red- and blue-light-emitting fluorophores on the edge successfully reproduced the purple light. The relative PL intensities of the fluorophores could be regulated by the excitation wavelength, enabling multicolor emission between blue and red light. Owing to the triphenylamine units of the fluorophores, the NGs showed PL enhancement due to aggregation. This characteristic was valuable for the fabrication of solid polymer materials. Specifically, the functionalized NGs can be dispersed into polyvinylidene difluoride. The resultant polymer films emitted red, blue, and purple color. Our study demonstrated the potential applicability of NGs for fluorophore carriers capable of reproducing intermediate colors of light.