Photothermal treatment of ESBL E. coli via Fe3O4 nanoparticles
Te-Wei Chang 1、Yi-Chun Chiu2、Chih-Chia Huang3
1Urology department, Zhongxiao Branch, Taipei City Hospital
2Urology department, Heping Branch, Taipei City Hospital
3Dept. of Photonics, National Cheng Kung University, Tainan
Purpose: Iron oxide-mediated photothermal treatment has been revealed as the next generation of noninvasive nanoagent. Nevertheless, the limitations of short-lasting of photon-to-thermal conversion, poor production rate, and only NIR absorption were compromised its clinical application. Therefore, we developed a Fe3O4 nanostructure with an interfacial charge between tannic acid (TNA) and iron ions to improve photon-to-thermal conversion rate and to broaden the absorption wavelengths.
Materials and Methods: After TNA-assisted hydrothermal reaction, commercial Fe2O3 nanopowder (IONP) was transferred to black colloidal IONP-TNA nanoparticles (NPs). Then, d-mannose was mixed with IONP-TNA for 1 hour and IONP-TNA@Man NPs were synthesized. Ultraviolet–visible spectroscopy was used to identify the absorption wavelengths band. Furthermore, we cultured extended-spectrum β-lactamases (ESBL) E. coli with 200ppm[Fe] IONP-TNA@Man NPs. TEM image was used to determine the adhesion ability to E. coli. After 30 minutes co-culture, the bacteria was exposed to an 808nm light irradiation at 135mW (2.25W/cm2) for 10 minutes. Bactericidal effect was exhibited via photograph of LIVE/DEAD BacLight™ assay and measurement of ATP level of bacteria. Besides bacteria, the human bladder SV-HUC1 cell was also cultured for 24 hours with IONP-TNA@Man NPs to determine the cytotoxicity to human urothelium.
Results: Via TNA assist, a gram-scaled synthesis with 88% production rate was observed. The absorption spectrum of IONP-TNA@Man NPs was elevated in the visible light region, comparing to IONP. The LIVE/DEAD BacLight™ assay changed from massive green (alive) to massive red (dead) signals after culture with IONP-TNA@Man NPs and light irradiation. ATP level remarkably dropped to below than 50% at 4 minutes irradiation and only 20% left after 10 minutes irradiation. The viability of human bladder SV-HUC1 cell showed no significant change from control group to 800 ppm[Fe] IONP-TNA@Man NPs.
Conclusion: We developed a Fe3O4 nanostructure with higher production rate and wider absorption wavelength. Photothermal treatment to ESBL E. coli by IONP-TNA@Man NPs exhibited not only good bactericidal effect but also minimal cytotoxicity to human bladder cell. Further studies in vivo were needed to valid its character in future clinical application.