Multifunctional Nanovectors Based on Polyamidoamine Polymers for Theranostic Application

AIE active polymers for biological applications

The discovery of aggregation-induced emission (AIE) phenomenon, significantly altered the understanding of the scientific world about the luminophore aggregation. Polymers with AIE features have recently emerged as promising materials with wide range of applications in optoelectronics devices, chemosensors, bioimaging, cancer theranostics and drug delivery. By introducing the AIE active molecule into the polymer structure, novel materials encompassing the characteristics properties of both the functional materials such as excellent brightness, versatile structure modification, high biocompatibility, exceptional stability and facile processability are achieved. This chapter presents the advances in synthetic design as well as potential biological applications of AIE active polymers, beginning with a brief introduction to the AIE phenomenon. The versatile synthetic route, easier functionalization, and light up feature of the AIE active polymers offer direct visualization of the physiological processes within or outside the living organisms. This chapter also precisely describes the photodynamic therapy/photothermal therapy (PDT/PTT) with up-to-date advancement of AIE active polymer and their emerging applications in biomedical field. The AIE active Photosensitizers (PSs) are much more efficient in singlet oxygen (¹O₂) production than their small molecule AIE active PSs due to their enhanced inter system crossing (ISC) process and improved light-harvesting ability. Additionally, the present chapter aims to focus on all recent AIE active polymers for drug screening and drug delivery. The AIE active polymer often shows decent drug loading capacity, high stability and good biocompatibility comprising image guided drug monitoring features. Lastly, the concluding discussion reveals the future prospective of the AIE active polymers.

Donor-Acceptor-Type Conjugated Polymer-Based Multicolored Drug Carriers with Tunable Aggregation-Induced Emission Behavior for Self-Illuminating Cancer Therapy

Nowadays, multicolored drug carriers have exhibited high significance in designing self-illuminating drug delivery systems to adapt different experimental conditions. In this study, we developed an efficient strategy for self-illuminating antitumor therapy using multicolored aggregation-induced emission (AIE)-active drug carriers by tuning electron donor moieties in donor-acceptor (D-A) structures. Three amphipathic conjugated polymers, P1 to P3, were successfully synthesized using an AIE-active tetraphenylethylene (TPE) moiety and donor-acceptor (D-A)-type electronic structure. Interestingly, the fluorescence behavior of P1 to P3 could be tuned between aggregation-caused quenching and AIE by changing the electron donor moiety. Their fluorescence color in aqueous solution could be easily adjusted from yellow to red by choosing stronger electron donors. After the anticancer drug paclitaxel was loaded, two AIE-active polymers, P1 and P2, could be engineered into polymer dots (Pdots) and applied in self-illuminating cancer therapy. The Pdots could not only reveal their location by a yellow- or red-colored fluorescence signal but also exhibit almost two times in vivo antitumor efficacy, high biocompatibility, and obvious tumor-targeting behavior compared to the commercially available anticancer drug Taxol. Furthermore, P2dots exhibited similar in vivo antitumor efficacy and biocompatibility compared to nonemission Abraxane, a commercially available drug delivery system. This work demonstrates the significant application of a D-A-type structure in the design of self-illuminating drug delivery systems.

Superparamagnetic Oxygen-Loaded Nanobubbles to Enhance Tumor Oxygenation During Hyperthermia

Tumor oxygenation is a critical issue for enhancing radiotherapy (RT) effectiveness. Alternating RT with hyperthermia improves tumor radiosensitivity by inducing a massive vasodilation of the neoangiogenic vasculature provided the whole tumor is properly heated. The aim of this work was to develop superparamagnetic oxygen-loaded nanobubbles (MOLNBs) as innovative theranostic hyperthermic agents to potentiate tumor oxygenation by direct intracellular oxygen administration. Magnetic oxygen-loaded nanobubbles were obtained by functionalizing dextran-shelled and perfluoropentane-cored nanobubbles with superparamagnetic iron oxide nanoparticles. Magnetic oxygen-loaded nanobubbles with sizes of about 380 nm were manufactured, and they were able to store oxygen and in vitro release it with prolonged kinetics. In vitro investigation showed that MOLNBs can increase tissue temperature when exposed to radiofrequency magnetic fields. Moreover, they are easily internalized by tumor cells, herein releasing oxygen with a sustained kinetics. In conclusion, MOLNBs can be considered a multimodal theranostic platform since, beyond their nature of contrast agent for magnetic resonance imaging due to magnetic characteristics, they showed echogenic properties and can be visualized using medical ultrasound.