A Multiresponsive Nanohybrid to Enhance the Lysosomal Delivery of Oxygen and Photosensitizers

Manganese Dioxide-Based Nanomaterials for Medical Applications

Manganese dioxide (MnO2) nanomaterials can react with trace hydrogen peroxide (H2O2) to produce paramagnetic manganese (Mn2+) and oxygen (O2), which can be used for magnetic resonance imaging and alleviate the hypoxic environment of tumors, respectively. MnO2 nanomaterials also can oxidize glutathione (GSH) to produce oxidized glutathione (GSSG) to break the balance of intracellular redox reactions. As a consequence of the sensitivity of the tumor microenvironment to MnO2-based nanomaterials, these materials can be used as multifunctional diagnostic and therapeutic platforms for tumor imaging and treatment. Importantly, when MnO2 nanomaterials are implanted along with other therapeutics, synergetic tumor therapy can be achieved. In addition to tumor treatment, MnO2-based nanomaterials display promising prospects for tissue repair, organ protection, and the treatment of other diseases. Herein, we provide a thorough review of recent progress in the use of MnO2-based nanomaterials for biomedical applications, which may be helpful for the design and clinical translation of next-generation MnO2 nanomaterials.

Photodynamic therapy with light-emitting diode arrays producing different light fields induces apoptosis and necrosis in gastrointestinal cancer

Introduction

Light-emitting diodes (LEDs) have become a new light source for photodynamic therapy (PDT) because of their excellent optical properties, small size, and low cost. LED arrays have so far been designed to meet the need for accurate illumination of irregular lesions. However, LED arrays determine not only the shape of the illuminated spot but also the light field, which has a significant impact on the efficacy of PDT.

Methods

We designed three types of LED arrays producing different light fields, namely an intensive LED array for a uniform light field, a sparse LED array for a non-uniform light field, and a point LED array for a Gaussian-like light field, and investigated the effect and mechanism of these light fields on PDT for gastrointestinal cancer both in vitro and in vivo.

Results

We found that intensive LED-PDT induced earlier and more serious cell death, including apoptosis and necrosis, than sparse LED-PDT and point LED-PDT. Among the three LED arrays, the intensive LED array induced cells to produce more differential proteins (DEPs), mainly related to mitochondria, ribosomes, and nucleic acids. DEPs in cells subjected to sparse LED- and point LED-PDT were mainly involved in extracellular activities. For MGC-803 tumor-bearing mice, intensive LED-PDT and point LED-PDT had better tumor ablation effect than sparse LED-PDT. Notably, recurrence was observed on day 7 after sparse LED-PDT. VCAM-1 and ICAM-1 were highly expressed in sparse LEDs-PDT treated tumor tissues and were associated tumor angiogenesis, which in turn lead to poor tumor suppression.

Conclusions

Therefore, the type of LED array significantly affected the performance of PDT for gastrointestinal cancer. Uniform light field with low power densities work better than non-uniform and Gaussian-like light fields.

Thiolated hyaluronic acid and catalase-enhanced CD44-targeting and oxygen self-supplying nanoplatforms with photothermal/photodynamic effects against hypoxic breast cancer cells

Photothermal and photodynamic therapies (PTT/PDT) have been widely accepted as noninvasive therapeutic methods for cancer treatment. However, tumor hypoxia and insufficient delivery of photoactive compounds to cancer cells can reduce the efficacy of phototherapy. Herein, we first synthesized thiolated hyaluronic acid (THA) and then conjugated it with catalase (CAT) onto chlorin e6 (Ce6)-adsorbed small gold nanorods (Ce6@sAuNRs) with near-infrared (NIR)/visible light activated photothermal/photodynamic effects. The conjugation of THA and CAT on Ce6@sAuNRs resulted in a red-shift of the longitudinal LSPR absorption band of sAuNRs up to 1000 nm and maintained the excellent enzymatic activity of catalase. Modification of Ce6@sAuNRs with THA resulted in efficient internalization of the nanocomposite into MCF-7/ADR multidrug-resistant (MDR) breast cancer cells (CD44+), thereby significantly enhancing the intracellular accumulation of the photosensitizer Ce6. CAT endows Ce6@sAuNRs with self-supporting oxygen production, which enables them to efficiently generate singlet oxygen (¹O₂) under 660 nm laser irradiation and enhances the photodynamic effect against hypoxic breast cancer cells. The results highlight the prospect of this novel multi-functional nanoplatform integrating active biological macromolecules (THA and CAT) into photosensitizer/photothermal gold nanocomposites in overcoming the limitations of hypoxic MDR breast cancer cell treatment.