Oral Microalgae-Nano Integrated System against Radiation-Induced Injury

Abstract

The increasing applications of ionizing radiation in society raise the risk of radiation-induced intestinal and whole-body injury. Astaxanthin is a powerful antioxidant to reduce the reactive oxygen generated from radiation and the subsequent damage. However, the oral administration of astaxanthin remains challenging owing to its low solubility and poor bioavailability. Herein, we facilely construct an orally used microalgae-nano integrated system (SP@ASXnano) against radiation-induced intestinal and whole-body injury, combining natural microalgae Spirulina platensis (SP) with astaxanthin nanoparticles (ASXnano). SP and ASXnano show complementation in drug delivery to improve distribution in the intestine and blood. SP displays limited gastric drug loss, prolonged intestinal retention, constant ASXnano release, and progressive degradation. ASXnano improves drug solubility, gastric stability, cell uptake, and intestinal absorption. SP and ASXnano have synergy in many aspects such as anti-inflammation, microbiota protection, and fecal short-chain fatty acid up-regulation. In addition, the system is ensured with biosafety for long-term administration. The system organically combines the properties of microalgae and nanoparticles, which was expected to expand the medical application of SP as a versatile drug delivery platform.

Oral administration microrobots for drug delivery

“…Until recent years, their application as biological entities in the field of biomedicine have gained attention. Many types of microalgae are considered non-toxic, biocompatible, and biodegradable natural materials, such as spirulina [ 16 ], chlorella [ 17 ], diatoms [ 18 ], etc.…”

“…The oral administration of this digestible microalga has shown antioxidative, anti-inflammatory effects, and regulation of intestinal microbiota, which would be beneficial to the prevention and treatment of many intestinal diseases [ 20 ]. Many researchers have reported the use of SP as a microcarrier to construct oral drug delivery microrobots, and has shown effective improvement in intestinal retention, slow release, anti-inflammatory and other effects [ 16 ]. Diatoms are single-celled eukaryotic microalgae with numerous metal-binding sites on their surfaces, exhibiting high adsorption capacity for heavy metals [ 18 ].…”

“…Combining natural microalgae Spirulina platensis (SP) with astaxanthin nanoparticles (ASXnano) allows for the full utilization of their complementary and synergistic effects. This achieves improvements in the distribution of drugs in the intestines and blood, protects intestinal microbial populations, and ultimately mitigates radiation-induced intestinal and systemic damage [ 16 ].

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Janus ACSP Nanoparticle for Synergistic Chemodynamic Therapy and Radiosensitization

“…6,7 The key issue in radiotherapy is the relatively high dose of X-rays, leading to side effects on peripheral normal tissues. 8,9 Hypoxic tumor cells are not sensitive to ionizing radiation. 10−12 The mild damaged DNA can be repaired through nonhomologous end joining 13 and homologous recombination (HR) repair pathways, 14,15 protecting the tumor cells from necrosis and apoptosis.…”

“…Radiotherapy (RT) serves as a valid common treatment modality for postoperative or neoadjuvant cancer treatment in the clinic. − The radiotherapy efficacy is determined by the direct damage of tumor cell DNA owing to the high-energy hydrated electrons without depth limitation and indirect damage of the generated reactive oxygen species (ROS), , and is influenced by multiple factors, such as irradiation resistance and DNA damage repair capability. , The key issue in radiotherapy is the relatively high dose of X-rays, leading to side effects on peripheral normal tissues. , Hypoxic tumor cells are not sensitive to ionizing radiation. − The mild damaged DNA can be repaired through nonhomologous end joining and homologous recombination (HR) repair pathways, , protecting the tumor cells from necrosis and apoptosis.…”