Skip to main content
Log in

Combining TiO2 photonic crystals and reagents enhances the sensitivity of endotoxin detection

  • Short Communication
  • Published:
Chemical Papers Aims and scope Submit manuscript

Abstract

Endotoxins are lipopolysaccharides, which are components of the cell wall of gram-negative bacteria, and are considerable risk to human health. Additionally, endotoxins are heat-stable and cannot be degenerated under normal sterilization conditions. Therefore, it is important to ensure that pharmaceuticals are not contaminated with endotoxins or that the contamination level is below the standard value. The simple gelation method has been widely used for endotoxin detection using limulus amebocyte lysate (LAL) reagents, but this detection sensitivity is quite low. We improved the sensitivity of endotoxin detection by combining a simple optical system using titanium oxide (TiO2) photonic crystals (PhCs) and LAL reagents. The response principle was to measure changes in the refractive index during the gelation process of LAL reagents induced by endotoxins. TiO2 PhC can be fabricated using a liquid phase deposition method. The TiO2 PhCs exhibited a peak derived from the nanostructure, and the wavelength peak at 630 nm was used for endotoxin detection based on the calculations of finite-difference time-domain simulation. We evaluated the detection method by performing spectral measurement of the gelation process of LAL reagents on PhCs. We confirmed that the peak wavelength shifted with increasing endotoxin concentrations and reaction times. We obtained the limit of detection for endotoxins as 0.0002 endotoxin units/mL and linear range of 0.001–1 EU/mL from the result at a reaction time of 60 min. The limit of detection was the lowest limit reported to date.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4

References

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Tatsuro Endo.

Ethics declarations

Conflict of interest

The authors declare no conflict of interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (DOCX 2266 KB)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Nishitsuji, R., Ueda, S., Sueyoshi, K. et al. Combining TiO2 photonic crystals and reagents enhances the sensitivity of endotoxin detection. Chem. Pap. 77, 611–615 (2023). https://doi.org/10.1007/s11696-022-02485-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s11696-022-02485-6

Keywords

Navigation