Photosensitizers with Aggregation-induced Emission and Their Biomedical Applications

Photodynamic bactericidal nanomaterials in food packaging: From principle to application

Compared to traditional preservatives, photodynamic inactivation (PDI) offers a promising bactericidal approach due to its nontoxic nature and low propensity for microbial resistance. In this paper, we initially investigate the principles and antibacterial mechanisms underlying PDI. We then review factors influencing PDI's germicidal efficacy in food preservation. Furthermore, we delve into the application potential of PDI nanomaterials, such as quantum dots, titanium dioxide, and graphene, in packaging and films. Special attention is given to the impact of PDI treatment on food quality and the potential for microbial tolerance development. Last, we discuss the migration and safety of PDI nanomaterials. The chemical basis of PDI involves the generation of reactive oxygen species through the activation of endogenous or exogenous photosensitizers. Its primary antibacterial mechanisms encompass the disruption of cell membranes, impairment of cellular functions, and inhibition of quorum sensing. The multi-target action of PDI significantly reduces the likelihood of resistance development. PDI has great potential for application in the field of antibacterial packaging. The information contained in this paper will provide effective reference for the design of new antibacterial packaging.

Photodynamic therapy-induced precise attenuation of light-targeted semicircular canals for treating intractable vertigo

Vertigo is a common symptom of various diseases that affects a large number of people worldwide. Current leading treatments for intractable peripheral vertigo are to intratympanically inject ototoxic drugs such as gentamicin to attenuate the semicircular canal function but inevitably cause hearing injury. Photodynamic therapy (PDT) is a noninvasive therapeutic approach by precisely targeting the diseased tissue. Here, we developed a PDT-based method for treating intractable peripheral vertigo in a mouse model using a polymer-coated photosensitizer chlorin e6 excited by red light. We found that a high dose of PDT attenuated the function of both semicircular canals and otolith organs and damaged their hair cells. Conversely, the PDT exerted no effect on hearing function or cochlear hair-cell viability. These results suggest the therapeutic potential of PDT for treating intractable peripheral vertigo without hurting hearing. Besides, the attenuation level and affected area can be precisely controlled by adjusting the light exposure time. Furthermore, we demonstrated the potential of this therapeutic approach to be minimally invasive with light irradiation through bone results. Thus, our PDT-based approach for attenuating the function of the semicircular canals offers a basis for developing a less-invasive and targeted therapeutic option for treating vertigo.

Natural AIEgens as Ultraviolet Sunscreens and Photosynergists for Solar Fuel Production

Bio-nano hybrids (BNH), combining semiconductors and microorganisms, have shown great promise for effective solar-to-fuel energy conversion. However, the high-energy ultraviolet (UV) photons in the solar spectrum can cause severe photocorrosion of semiconductors and irreversible photodamage to microorganisms within BNH. Here, we developed an encapsulation strategy using natural luminogens with aggregation-induced emission characteristics (AIEgens) to construct a protective layer for BNH, effectively shielding them against high-energy UV photons. We incorporated natural berberine (BBR) into the BNH composed of Methanosarcina barkeri and polymeric carbon nitrides (CNx). The self-assembled BNH-BBR system displayed a 2.75-fold higher CH4 yield than BNH under simulated solar irradiation. Mechanism analysis revealed that BBR acted as a UV sunscreen for BNH by converting high-energy short wavelengths into low-energy long wavelengths, thereby reducing the accumulation of reactive oxygen species and alleviating the photocorrosion of CNx. Furthermore, BBR functioned as a photosynergist for BNH by regulating photoelectron production and utilization, enhancing the intracellular energy formation in M. barkeri for growth and metabolism. This work provides important insights into the effective and scalable conversion of CO2 into valuable biofuels with BNH under light illumination containing high-energy photons.

AIE-Based & Organic Luminescent Materials: Nanoarchitectonics and Advanced Applications

Organic luminescence materials makes the molecule more enthusiastic in wide variety of applications. The luminescent organic materials are in a attraction of the researchers, and the Aggregation-Induced Emission (AIE) is attributed to the occurrence that particular chromophores (typically fluorophores) display very low or nearly no emission in the monomolecular soluble state but become highly emissive when forming aggregates in solution or in solid state. This phenomenon is relatively abnormal when compared with many other traditional fluorophores. AIE research suppresses aggregation-caused quenching (ACQ). Nevertheless, the carbon dots (CDs) and quantum dots have shown to have tyical florescence properties, therefore, recent years many researchers have also attracted for their developments. The CDs, luminescent, and AIE materials are not only used in biomedical applications and organic light-emitting diodes but also in sensing, self-assembly, and other areas. One should introduce promising material to a designed framework that exhibits AIE characteristics to ensure moral results in AIE. Amongest, AIE-active tetraphenylethylene (TPE) is attractive fluorophores due to its easy synthesis strategy. This review article discusses the synthesis properties of TPE, CDs, and luminescent materials with a broad range of applications. We have outlined linear, branched-shaped supramolecular, and hybrid macromolecules due to its potential in the future.

Extracellular Vesicle-Inspired Therapeutic Strategies for the COVID-19

Emerging infectious diseases like coronavirus pneumonia (COVID-19) present significant challenges to global health, extensively affecting both human society and the economy. Extracellular vesicles (EVs) have demonstrated remarkable potential as crucial biomedical tools for COVID-19 diagnosis and treatment. However, due to limitations in the performance and titer of natural vesicles, their clinical use remains limited. Nonetheless, EV-inspired strategies are gaining increasing attention. Notably, biomimetic vesicles, inspired by EVs, possess specific receptors that can act as "Trojan horses," preventing the virus from infecting host cells. Genetic engineering can enhance these vesicles by enabling them to carry more receptors, significantly increasing their specificity for absorbing the novel coronavirus. Additionally, biomimetic vesicles inherit numerous cytokine receptors from parent cells, allowing them to effectively mitigate the "cytokine storm" by adsorbing pro-inflammatory cytokines. Overall, this EV-inspired strategy offers new avenues for the treatment of emerging infectious diseases. Herein, this review systematically summarizes the current applications of EV-inspired strategies in the diagnosis and treatment of COVID-19. The current status and challenges associated with the clinical implementation of EV-inspired strategies are also discussed. The goal of this review is to provide new insights into the design of EV-inspired strategies and expand their application in combating emerging infectious diseases.

Robust Natural Light-Absorbable and -Degradable AIE Photosensitizers for Fluorescence Labeling and Efficient Photodynamic Eradication of Algal Pollutants

Current water pollution caused by the excessive proliferation of harmful algae urges green methods that can efficiently utilize natural light to treat algal pollution. Herein, a series of aggregation-induced emission (AIE) photosensitizers that can efficiently harness sunshine were synthesized for the environmentally friendly and biocompatible treatment of algal pollution. By tuning the number of thiophene units and the electron conjugation degree, the photosensitizers' absorptions were broadened to cover the whole visible light range. The positive charges guided photosensitizers to aggregate on algal cell surfaces, resulting in a turn-on fluorescence signal and robust reactive oxygen species generation under sunshine, thereby achieving fluorescence labeling and photodynamic eradication of algae. The eradication outcomes demonstrated that the AIE photosensitizers significantly outperformed the commercial algaecide ALG. At 20 ppm photosensitizers, 90.4% and 94.2% killing rates were achieved for C. reinhardtii and C. vulgaris, respectively, 2.8- and 3.6-fold higher than those from the same concentration of ALG. Excellent performances in inhibiting algae growth were also verified with efficiency superior to that of ALG. Importantly, the photosensitizers can self-degrade into biocompatible fragments under irradiation to avoid secondary pollution. The developed photosensitizers that possess sunshine convertibility and degradability provide an efficient tool for algal treatment, showing broad research and application prospects.

Aggregation-induced emission of TTCPy-3: A novel approach for eradicating Nocardia seriolae infections in aquatic fishes

Aquatic fishes are threatened by the strong pathogenic bacterium Nocardia seriolae, which challenges the current prevention and treatment approaches. This study introduces luminogens with aggregation-induced emission (AIE) as an innovative and non-antibiotic therapy for N. seriolae. Specifically, the AIE photosensitizer, TTCPy-3 is employed against N. seriolae. We evaluated the antibacterial activity of TTCPy-3 and investigated the killing mechanism against N. seriolae, emphasizing its ability to aggregate within the bacterium and produce reactive oxygen species (ROS). TTCPy-3 could effectively aggregate in N. seriolae, generate ROS, and perform real-time imaging of the bacteria. A bactericidal efficiency of 100% was observed while concentrations exceeding 4 μM in the presence of white light irradiation for 10 min. In vivo, evaluation on zebrafish (Danio rerio) confirmed the superior therapeutic efficacy induced by TTCPy-3 to fight against N. seriolae infections. TTCPy-3 offers a promising strategy for treating nocardiosis of fish, paving the way for alternative treatments beyond traditional antibiotics and potentially addressing antibiotic resistance.

pH-/Redox-Responsive Nanodroplet Combined with Ultrasound-Targeted Microbubble Destruction for the Targeted Treatment of Drug-Resistant Triple Negative Breast Cancer

Multiple drug resistance (MDR) exists in divergent cancers including triple negative breast cancer (TNBC) and partly results in the resistance to many first-line anti-cancer agents, bringing a big challenge to TNBC management. To develop novel TNBC therapeutics, in our study, a hyaluronic acid (HA)-carboxymethyl chitosan (CMC) conjugate linked via a disulfide-bond (HA-SS-CMC, HSC) was synthesized to fabricate nanodroplets (NDs). The NDs encapsulating doxorubicin (DOX) and perfluorohexane (DOX-HSC-NDs) were prepared via a homogenization/emulsification strategy and exhibited not only high biocompatibility but also noticeable tumor cell targeting ability and dual pH/redox responsiveness. Besides, DOX-HSC-NDs can be used as a contrast-enhanced ultrasound imaging agent for specific tumor imaging. DOX-HSC-NDs in combination with ultrasound targeted microbubble destruction could improve intracellular drug aggregation and retention of MDR cells and work against multiple mechanisms of drug resistance through synergistic strategies, including up-regulating the reactive oxygen species (ROS) level, promoting apoptosis, and scavenging glutathione, while reducing the expression levels of P-glycoprotein and inhibiting the epithelial-mesenchymal transition. This combination strategy showed protective effects against TNBC in both MDA-MB-231/ADR cells and tumor-bearing mice. Our study for the first time developed and reported the ultrasound-augmented HSC-NDs as the DOX nanocarrier and provided scientific evidence to support the future application of DOX-HSC-NDs as a potential TNBC therapy.

Stimuli-Responsive Gene Delivery Nanocarriers for Cancer Therapy

Gene therapy provides a promising approach in treating cancers with high efficacy and selectivity and few adverse effects. Currently, the development of functional vectors with safety and effectiveness is the intense focus for improving the delivery of nucleic acid drugs for gene therapy. For this purpose, stimuli-responsive nanocarriers displayed strong potential in improving the overall efficiencies of gene therapy and reducing adverse effects via effective protection, prolonged blood circulation, specific tumor accumulation, and controlled release profile of nucleic acid drugs. Besides, synergistic therapy could be achieved when combined with other therapeutic regimens. This review summarizes recent advances in various stimuli-responsive nanocarriers for gene delivery. Particularly, the nanocarriers responding to endogenous stimuli including pH, reactive oxygen species, glutathione, and enzyme, etc., and exogenous stimuli including light, thermo, ultrasound, magnetic field, etc., are introduced. Finally, the future challenges and prospects of stimuli-responsive gene delivery nanocarriers toward potential clinical translation are well discussed. The major objective of this review is to present the biomedical potential of stimuli-responsive gene delivery nanocarriers for cancer therapy and provide guidance for developing novel nanoplatforms that are clinically applicable.

Structure and functions of Aggregation-Induced Emission-Photosensitizers in anticancer and antimicrobial theranostics

Photosensitizers with Aggregation-Induced Emission (AIE) can allow the efficient light-mediated generation of Reactive Oxygen Species (ROS) based on their complex molecular structure, while interacting with living cells. They achieve better tissue targeting and allow penetration of different wavelengths of Ultraviolet-Visible-Infrared irradiation. Not surprisingly, they are useful for fluorescence image-guided Photodynamic Therapy (PDT) against cancers of diverse origin. AIE-photosensitizers can also function as broad spectrum antimicrobials, capable of destroying the outer wall of microbes such as bacteria or fungi without the issues of drug resistance, and can also bind to viruses and deactivate them. Often, they exhibit poor solubility and cellular toxicity, which compromise their theranostic efficacy. This could be circumvented by using suitable nanomaterials for improved biological compatibility and cellular targeting. Such dual-function AIE-photosensitizers nanoparticles show unparalleled precision for image-guided detection of tumors as well as generation of ROS for targeted PDT in living systems, even while using low power visible light. In short, the development of AIE-photosensitizer nanoparticles could be a better solution for light-mediated destruction of unwanted eukaryotic cells and selective elimination of prokaryotic pathogens, although, there is a dearth of pre-clinical and clinical data in the literature.