Application of nanotechnology for enhancing photodynamic therapy via ameliorating, neglecting, or exploiting tumor hypoxia

Abstract

Photodynamic therapy (PDT), an oxygen‐dependent modality, has been clinically approved and is considered a promising approach for cancer treatment. However, PDT shows noticeable limits due to the hypoxic nature of most solid tumor microenvironments. In recent years, various strategies have been developed to overcome tumor hypoxia either via oxygen‐replenishing approaches or via diminishing oxygen dependence. Both of these approaches have shown promise in reversing hypoxia‐relevant PDT resistance and thus improve antitumor efficacy. However, the low oxygen level at the tumor site is also an opportunity for the development of new therapeutic modalities, such as hypoxia‐activated chemotherapy, hypoxia‐inducible drug release, and starvation therapy. Therefore, a combination of these therapeutic modalities with PDT could promote their synergetic efficacy. Herein, we present an overview of the recent trend in the modulation and utilization of tumor hypoxia via nanomedicine‐based strategies, followed by a summary of the design and mechanisms of these nanosystems to improve PDT. Finally, current challenges and future perspectives for how PDT can achieve more extensive clinical applications for cancer therapy are discussed.

Improved Stability and Photothermal Performance of Polydopamine‐Modified Fe3O4 Nanocomposites for Highly Efficient Magnetic Resonance Imaging‐Guided Photothermal Therapy

“…Various nanomaterials have been explored for biomedical applications in recent decades due to their unique advantages of tunable sizes, controllable surface properties, good biocompatibility, and passive targeting ability, which is caused by an enhanced permeability and retention (EPR) effect. [ 14–18 ] Among them, magnetic iron oxide nanoparticles have attracted extensive attention, and some of them, such as Feridex and Resovist, have been approved as T 2 ‐weighted MRI contrast agents for clinical liver disease diagnosis. [ 19–22 ] These commercial magnetic iron oxide nanoparticles were synthesized by a coprecipitation method in an aqueous solution at low temperature, resulting in poor stability, low crystallinity, and low transverse relaxivity.…”

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

“…70B), PDT can be divided into type I and type II mechanisms. 450,451 For the type I mechanism, the triplet excited PS interacts with biological substrates to generate free radicals by transferring electrons. These free radicals subsequently react with oxygen or water to form ROS such as hydrogen peroxide (H 2 O 2 ), hydroxyl radical (cOH), and superoxide anion (cO 2 À ).…”

In Vivo Dynamic Monitoring of Bacterial Infection by NIR‐II Fluorescence Imaging

“…A balance exists between bacterial infection and the immune system in a variety of diseases. [4][5][6] The ideal time to initiate antibiotic treatment is a stage when our immune system cannot bear the bacterial burden, facing an imminent threat to health. On the other hand, it is unnecessary to adopt antibiotics when this balance has not been interrupted by bacterial infection yet, as our immune system is capable of clearing up a certain number of invasive bacteria on its own, thus preventing deterioration into a bacterial infectious disease.…”