Tianfu Zhang

Bio: Tianfu Zhang is an academic researcher from Hong Kong University of Science and Technology. The author has contributed to research in topics: OLED & Red Color. The author has an hindex of 3, co-authored 5 publications receiving 301 citations.

Bright Near-Infrared Aggregation-Induced Emission Luminogens with Strong Two-Photon Absorption, Excellent Organelle Specificity, and Efficient Photodynamic Therapy Potential.

Abstract: Far-red and near-infrared (NIR) fluorescent materials possessing the characteristics of strong two-photon absorption and aggregation-induced emission (AIE) as well as specific targeting capability are much-sought-after for bioimaging and therapeutic applications due to their deep penetration depth and high resolution. Herein, a series of dipolar far-red and NIR AIE luminogens with a strong push-pull effect are designed and synthesized. The obtained fluorophores display bright far-red and NIR solid-state fluorescence with a high quantum yield of up to 30%, large Stokes shifts of up to 244 nm, and large two-photon absorption cross-sections of up to 887 GM. A total of three neutral AIEgens show specific lipid droplet (LD)-targeting capability, while the one with cationic and lipophilic characteristics tends to target the mitochondria specifically. All of the molecules demonstrate good biocompatibility, high brightness, and superior photostability. They also serve as efficient two-photon fluorescence-imaging agents for the clear visualization of LDs or mitochondria in living cells and tissues with deep tissue penetration (up to 150 μm) and high contrast. These AIEgens can efficiently generate singlet oxygen upon light irradiation for the photodynamic ablation of cancer cells. All of these intriguing results prove that these far-red and NIR AIEgens are excellent candidates for the two-photon fluorescence imaging of LDs or mitochondria and organelle-targeting photodynamic cancer therapy.

In Situ Monitoring Apoptosis Process by a Self-Reporting Photosensitizer.

Abstract: Although photodynamic therapy (PDT) has thrived as a promising treatment, highly active photosensitizers (PSs) and intense light power can cause treatment overdose. However, extra therapeutic response probes make the monitoring process complicated, ex situ and delayed. Now, this challenge is addressed by a self-reporting cationic PS, named TPE-4EP+, with aggregation-induced emission characteristic. The molecule undergoes mitochondria-to-nucleus translocation during apoptosis induced by PDT, thus enabling the in situ real-time monitoring via fluorescence migration. Moreover, by molecular charge engineering, we prove that the in situ translocation of TPE-4EP+ is mainly attributed to the enhanced interaction with DNA imposed by its multivalent positive charge. The ability of PS to provide PDT with real-time diagnosis help control the treatment dose that can avoid excessive phototoxicity and minimize potential side effect. Future development of new generation of PS is envisioned.

Multifunctional Supramolecular Assemblies with Aggregation-Induced Emission (AIE) for Cell Line Identification, Cell Contamination Evaluation, and Cancer Cell Discrimination.

Abstract: It is undoubted the important role of cells in biology and medicine, but worldwide misidentified and cross-contaminated cell lines have caused much trouble in related fields. Herein, three kinds of supramolecular AIE (aggregation-induced emission) nanoassemblies were constructed by the host-guest interaction between tetraphenylethene (TPE) derivatives and cucurbit[8]uril (CB[8]). Based on the recognized mechanism of AIE, the TPE derivatives could achieve stronger fluorescence emission and higher fluorescence quantum yield after assembling with CB[8]. Moreover, the constructed supramolecular AIE complexes obtained well-confirmed nanostructures and exhibited different sizes and shapes. Correspondingly, they generated characteristic biological properties and fluorescence enhancement of cells. Inspired by the concept of Big Data Analysis, these fluorescence signals were further transformed into a unique fingerprint of cells via linear discriminant analysis. Immediately, we realized the veracious identification between a normal cell line, two cancer cell lines, and two metastasized cancer cell lines in a qualitative analysis. More importantly, it was well used to monitor the evaluation of cross-contaminated cells and the discrimination of cancer cells. As a proper bioapplication of ideal supramolecular nanomaterials, this system was easy to learn and apply, and the whole procedure was kept to 20 min, without cell disruption, centrifugation, or washing steps.

Recent Advances in Aggregation-Induced Emission Materials and Their Biomedical and Healthcare Applications.

Abstract: The emergence of the concept of aggregation-induced emission (AIE) has opened new opportunities in many research areas, such as biopsy analysis, biological processes monitoring, and elucidation of key physiological and pathological behaviors. As a new class of luminescent materials, AIE luminogens (AIEgens) possess many prominent advantages such as tunable molecular structures, high molar absorptivity, high brightness, large Stokes shift, excellent photostability, and good biocompatibility. The past two decades have witnessed a dramatic growth of research interest in AIE, and many AIE-based bioprobes with excellent performance have been widely explored in biomedical fields. This review summarizes some of the latest advancements of AIE molecular probes and AIE nanoparticles (NPs) with regards to biomedical and healthcare applications. According to the research areas, the review is divided into five sections, which are imaging and identification of cells and bacteria, photodynamic therapy, multimodal theranostics, deep tissue imaging, and fluorescence-guided surgery. The challenges and future opportunities of AIE materials in the advanced biomedical fields are briefly discussed. In perspective, the AIE-based bioprobes play vital roles in the exploration of advanced bioapplications for the ultimate goal of addressing more healthcare issues by integrating various cutting-edge modalities and techniques.

“Simple” AIEgens for Non‐doped Solution‐Processed OLEDs with Emission Close to Pure Red in sRGB Gamut

Abstract: Herein, two red luminogens with aggregation-induced emission (AIE) characteristics based on simple D–A structures with high performance in the film state are explored. Efficient non-doped solution-processed organic light emitting diodes (OLEDs) are fabricated and emit bright red electroluminescence at 652 nm and 711 nm, respectively. Most importantly, they exhibit CIE coordinates of (0.63, 0.36) and (0.64, 0.35), respectively, which are close to that of primary red color (0.63, 0.34) according to the digital television standard.

Aggregation-Induced Emission: New Vistas at the Aggregate Level

Abstract: Aggregation-induced emission (AIE) describes a photophysical phenomenon in which molecular aggregates exhibit stronger emission than the single molecules. Over the course of the last 20 years, AIE research has made great strides in material development, mechanistic study and high-tech applications. The achievements of AIE research demonstrate that molecular aggregates show many properties and functions that are absent in molecular species. In this review, we summarize the advances in the field of AIE and its related areas. We specifically focus on the new properties of materials attained by molecular aggregates beyond the microscopic molecular level. We hope this review will inspire more research into molecular ensembles at and beyond the meso level and lead to the significant progress in material and biological science.

Photosensitizers for Photodynamic Therapy

Abstract: As an emerging clinical modality for cancer treatment, photodynamic therapy (PDT) takes advantage of the cytotoxic activity of reactive oxygen species (ROS) that are generated by light irradiating photosensitizers (PSs) in the presence of oxygen (O2 ). However, further advancements including tumor selectivity and ROS generation efficiency are still required. Substantial efforts are devoted to design and synthesize smart PSs with optimized properties for achieving a desirable therapeutic efficacy. This review summarizes the recent progress in developing intelligent PSs for efficient PDT, ranging from single molecules to delicate nanomaterials. The strategies to improve ROS generation through optimizing photoinduced electron transfer and energy transfer processes of PSs are highlighted. Moreover, the approaches that combine PDT with other therapeutics (e.g., chemotherapy, photothermal therapy, and radiotherapy) and the targeted delivery in cancer cells or tumor tissue are introduced. The main challenges for the clinical application of PSs are also discussed.

Supramolecular materials based on AIE luminogens (AIEgens): construction and applications

Abstract: The emergence of aggregation-induced emission luminogens (AIEgens) has significantly stimulated the development of luminescent supramolecular materials because their strong emissions in the aggregated state have resolved the notorious obstacle of the aggregation-caused quenching (ACQ) effect, thereby enabling AIEgen-based supramolecular materials to have a promising prospect in the fields of luminescent materials, sensors, bioimaging, drug delivery, and theranostics. Moreover, in contrast to conventional fluorescent molecules, the configuration of AIEgens is highly twisted in space. Investigating AIEgens and the corresponding supramolecular materials provides fundamental insights into the self-assembly of nonplanar molecules, drastically expands the building blocks of supramolecular materials, and pushes forward the frontiers of supramolecular chemistry. In this review, we will summarize the basic concepts, seminal studies, recent trends, and perspectives in the construction and applications of AIEgen-based supramolecular materials with the hope to inspire more interest and additional ideas from researchers and further advance the development of supramolecular chemistry.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy.

Abstract: This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Antibiotic-Free Antibacterial Strategies Enabled by Nanomaterials: Progress and Perspectives.

Abstract: Bacterial infection is one of the top ten leading causes of death globally and the worst killer in low-income countries. The overuse of antibiotics leads to ever-increasing antibiotic resistance, posing a severe threat to human health. Recent advances in nanotechnology provide new opportunities to address the challenges in bacterial infection by killing germs without using antibiotics. Antibiotic-free antibacterial strategies enabled by advanced nanomaterials are presented. Nanomaterials are classified on the basis of their mode of action: nanomaterials with intrinsic or light-mediated bactericidal properties and others that serve as vehicles for the delivery of natural antibacterial compounds. Specific attention is given to antibacterial mechanisms and the structure-performance relationship. Practical antibacterial applications employing these antibiotic-free strategies are also introduced. Current challenges in this field and future perspectives are presented to stimulate new technologies and their translation to fight against bacterial infection.