Ingestible light source for intragastric antibacterial phototherapy: a device safety study on a minipig model

Exploring the phototherapy modalities and dosages for an ingestible light-emitting diode capsule to eliminate Helicobacter pylori infection

Helicobacter pylori (H. pylori) infection presents increasing challenges to antibiotic therapies owing to limited drug bioavailability, multi-drug resistance and collateral damage to commensal intestinal microflora. To address these problems, here, an ingestible magnetically controlled light-emitting diode (LED) light source was designed for an ingestible capsule to perform antimicrobial photodynamic therapy (aPDT) without an exogenous photosensitizer (ex-PS) at 630 nm. Specifically, we first optimized the antibacterial rates of aPDT with ex-PS and aPDT without ex-PS against H. pylori at the bacterial suspension level by varying the wavelength (405, 530, 630 nm), photosensitizer concentration (2, 4, 6, 8, 10 μg/mL), power density (15, 30 mW/cm2), and energy density (0, 3.6, 7.2, 10.8, 14.4, 18.0 J/cm2). Then, we compared the antibacterial effect of aPDT with ex-PS and aPDT without ex-PS against H. pylori at the biofilm level, revealing that the antibacterial rate of aPDT without ex-PS reached approximately 97 % at 405 nm and 18 J/cm2, similar to that of aPDT with ex-PS under the same conditions. Furthermore, 80 SD rats infected with H. pylori were treated with aPDT with ex-PS and aPDT without ex-PS at the above wavelengths. Histopathological analysis of rat gastrointestinal tissues revealed that aPDT with ex-PS and aPDT without ex-PS exhibited significant antibacterial activity against H. pylori, without side effects on normal tissues. Additionally, aPDT without ex-PS at 630 nm induced an anti-inflammatory response and regulated the intestinal flora. Ultimately, we developed a magnetically controlled LED capsule for in vivo aPDT without ex-PS at 630 nm against H. pylori.

Research progress in photodynamic therapy for Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a pathogenic microorganism that colonizes the human gastric mucosa and can lead to various gastric disorders, including gastritis, gastric ulcers, and gastric cancer. However, the increasing prevalence of antibiotic resistance in H. pylori has prompted the search for alternative treatment options. Photodynamic therapy has emerged as a potential alternative therapy, thus offering the advantage of avoiding some of the side effects associated with antibiotics and effectively targeting drug-resistant strains. In the postantibiotic era, photodynamic therapy (PDT) has shown promise as a novel treatment for H. pylori infection. This review focused on elucidating the mechanism of photodynamic therapy in the treatment of H. pylori. Additionally, we present an overview of the current research on photodynamic therapy by examining both standalone photodynamic therapy and combination therapies for H. pylori infection treatment. Furthermore, the safety profile of photodynamic therapy was also evaluated. Finally, we discuss the challenges and prospects associated with this innovative technology, with an aim to provide new insights and methodologies for the treatment of H. pylori infection.

Miniaturized Capsule System Toward Real-Time Electrochemical Detection of H2 S in the Gastrointestinal Tract

Hydrogen sulfide (H2 S) is a gaseous inflammatory mediator and important signaling molecule for maintaining gastrointestinal (GI) homeostasis. Excess intraluminal H2 S in the GI tract has been implicated in inflammatory bowel disease and neurodegenerative disorders; however, the role of H2 S in disease pathogenesis and progression is unclear. Herein, an electrochemical gas-sensing ingestible capsule is developed to enable real-time, wireless amperometric measurement of H2 S in GI conditions. A gold (Au) three-electrode sensor is modified with a Nafion solid-polymer electrolyte (Nafion-Au) to enhance selectivity toward H2 S in humid environments. The Nafion-Au sensor-integrated capsule shows a linear current response in H2 S concentration ranging from 0.21 to 4.5 ppm (R2 = 0.954) with a normalized sensitivity of 12.4% ppm-1 when evaluated in a benchtop setting. The sensor proves highly selective toward H2 S in the presence of known interferent gases, such as hydrogen (H2 ), with a selectivity ratio of H2 S:H2 = 1340, as well as toward methane (CH4 ) and carbon dioxide (CO2 ). The packaged capsule demonstrates reliable wireless communication through abdominal tissue analogues, comparable to GI dielectric properties. Also, an assessment of sensor drift and threshold-based notification is investigated, showing potential for in vivo application. Thus, the developed H2 S capsule platform provides an analytical tool to uncover the complex biology-modulating effects of intraluminal H2 S.