# TiO2 eliminates Hymenolepis nana eggs via photocatalytic activity

## TL;DR

Titanium dioxide under UV light can inactivate Hymenolepis nana eggs by damaging their structure and function, potentially improving water treatment.

## Contribution

This study is the first to demonstrate TiO2's photocatalytic inactivation of parasitic Hymenolepis nana eggs.

## Key findings

- TiO2 photocatalysis under specific conditions effectively inactivates Hymenolepis nana eggs.
- The treatment causes structural damage and reduces mitochondrial function in the eggs.
- The infection rate in mice was reduced to 12.5% after TiO2 treatment.

## Abstract

Titanium dioxide (TiO2) exhibits bactericidal, fungicidal, and virucidal effects under ultraviolet light irradiation. However, there are few reports on the photocatalytic effect of TiO2 against parasitic eggs. This study aims to preliminarily investigate the effect of TiO2 photocatalysis on the inactivation of Hymenolepis nana (H. nana) eggs. We employed the trypan blue staining method to assess the survival rate of 100 insect eggs, investigating the roles of light, TiO2 concentration, solution pH and light intensity in the process of inactivating eggs with TiO2. Morphological and structural damage to the eggs was observed using electron microscopy. The levels of reactive oxygen species (ROS) and adenosine triphosphate (ATP) within the eggs were measured using a fluorescent enzyme labeler, and the infectivity of TiO2-treated eggs was evaluated by oral-gavage in mice (8 mice per group). The results showed that under mercury lamp irradiation, with a TiO2 concentration of 1.0 mg/L, pH values ranging from 6 to 8, light intensity of 0.50 mW/cm2, and photocatalytic exposure for 2 h effectively inactivated H. nana eggs. Electron microscopy revealed that TiO2 photocatalysis caused eggs shrinkage and collapse of the spherical structure, along with the decrease number of mitochondria within the eggs. The TiO2 photocatalysis resulted in an increase in ROS content and a decrease in ATP content in eggs. These findings indicate that TiO2 photocatalysis disrupts the structural integrity and mitochondrial function of H. nana eggs by elevating ROS levels and depleting ATP, while simultaneously reducing the infection rate in mice to 12.5%. This study lays the groundwork for potential future applications of TiO2-based photoenergy-mediated inactivation of parasitic eggs in wastewater and drinking water treatment, ultimately benefiting public health.

This study preliminarily investigated the inactivation of Hymenolepis nana (H. nana) eggs using titanium dioxide (TiO2) photocatalysis. The trypan blue staining method was used to assess eggs viability under varying conditions of light, TiO2 concentration, pH, and light intensity. Under conditions of TiO2 concentration at 1.0 mg/L, pH between 6 and 8, and light intensity at 0.50 mW/cm2, optimal inactivation effects can be achieved after 2 h of exposure to mercury lamp irradiation. Electron microscopy revealed that photocatalytic treatment caused eggs shrinkage, collapse of the spherical structure, and a reduction in mitochondrial number. Furthermore, a significant increase in reactive oxygen species (ROS) and a decrease in adenosine triphosphate (ATP) levels were detected within the eggs. These findings suggest that TiO2 photocatalysis inactivates H. nana eggs by disrupting their structural integrity and mitochondrial function. This work lays a foundation for the potential application of TiO2-based technology to inactivate parasitic eggs in water treatment, offering promise for public health protection.