PUKYONG

Investigation of photothermal treatment on biological tissues and microbial biofilms

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Abstract
Several thermal treatment techniques (radiofrequency RF, microwave MW, high-intensity focused ultrasound HIFU, cryotherapy, and photothermal treatment PTT) have been currently deployed to treat tumors and cancers. PTT is considered a minimally invasive surgery with high precision and less complication post-operation. However, carbonization is one of the common concerns for surgeons and patients during the disease treatment because it diminishes the light optical penetration and delays the wound healing process. Thus, planning and monitoring are necessary for the effectiveness and safety of PTT. Moreover, a flexible endoscope is commonly used to assist the PTT of internal organs by capturing images and transmitting the laser light to the selected target. However, endoscope-integrated PTT often suffers from secondary infection due to microorganism biofilms, which forms inside the working channel of the endoscope. Therefore, the endoscope is required to disinfect the microorganism biofilms before the next use. In this research, either a bare optical fiber or a basket-integrated diffusing optical device was used to deliver the laser lights (wavelengths = 1470 nm, 1064 nm, 808 nm, and 405 nm) to both treat the tumors/cancers and eradicate the microbial biofilms forming on the endoscope channels after use. Laser energy was modulated in a controllable manner to effectively coagulate the target region of the tissue without carbonization. The thermal response of biological tissues was investigated and validated by both computational and experimental models. Two laser lights (wavelengths = 808 nm and 405 nm) were also combined with a chemical agent (glutaraldehyde) to study the collective effects on the microorganism biofilms (Pseudomonas aeruginosa and Staphylococcus aureus) growing in both Teflon and clinical endoscope channels. To understand the physical interactions of bacteria and fungus within the dual biofilm, a microfluidic platform was then deployed to investigate the cross-kingdom biofilm (Staphylococcus aureus and Candida albicans) formation at a single-cell level under various hydrodynamic conditions. The current findings show effective coagulation of various tissue models ex vivo for both non-tubular and tubular organs suggesting potential modalities for the tumor/cancer treatment. The proposed techniques in this research monitored and controlled competently the temperature and coagulation region on the treated tumors/cancers. Furthermore, the proposed PTT combined with a chemical agent showed a more effective eradication of bacterial biofilms grown in the endoscope channel than the current standard treatment with 2% glutaraldehyde, implying an alternative approach of endoscope reprocessing for the surgeons. The microchannel in the microfluidic platform showed an apparent visualization of the adhesion, formation, and treatment of microorganism biofilms at the single-cell level, suggesting a real-time dose determination for biofilm cleaning/sterilization. The proposed feasible techniques will be further developed and validated in clinical settings in terms of treatment effectiveness, safety, and cost.
Author(s)
TRAN VAN NAM
Issued Date
2022
Awarded Date
2022. 2
Type
Dissertation
Publisher
부경대학교
URI
https://repository.pknu.ac.kr:8443/handle/2021.oak/24130
http://pknu.dcollection.net/common/orgView/200000606612
Affiliation
Pukyong National university, Graduate school
Department
대학원 의생명기계전기융합공학협동과정
Advisor
Hyun Wook Kang
Table Of Contents
Chapter 1: Introduction 1
1.1. Motivation 1
1.2. Therapeutic modalities for tumors and cancers 1
1.3. Energy modulation for photothermal treatment 3
1.4. Treatment methods of microbial biofilms 4
1.5. Goal and outline of thesis 5
1.6. References 7
Chapter 2: Numerical and experimental model of linear energy modulation for photothermal treatment of thyroid cancer 9
2.1. Introduction 9
2.2. Materials and Methods 11
2.3. Results 19
2.4. Discussion 26
2.5. Conclusion 32
2.6. References 32
Chapter 3: Investigation of laser-tissue interactions under optical energy modulation: numerical and experimental evaluations 35
3.1. Introduction 35
3.2. Materials and Methods 38
3.3. Results 47
3.4. Discussion 54
3.5. Conclusion 61
3.6. References 62
Chapter 4: Concentric photothermal treatment of tracheal stenosis with basketintegrated optical device 66
4.1. Introduction 66
4.2. Materials and Methods 68
4.3. Results 76
4.4. Discussion 85
4.5. Conclusion 89
4.6. References 90
Chapter 5: Photochemical treatment of bacterial biofilm using glutaraldehyde,near-infrared light, and blue light 93
5.1. Introduction 93
5.2. Materials and Methods 96
5.3. Results 103
5.4. Discussion 113
5.5. Conclusion 118
5.6. References 118
Chapter 6: Photochemical treatment for enhanced high-level disinfection of mature biofilm in Teflon and clinical models of endoscope channels 123
6.1. Introduction 123
6.2. Materials and Methods 127
6.3. Results 137
6.4. Discussion 151
6.5. Conclusion 154
6.6. References 154
Chapter 7: A real-time evaluation of microfluidic-assisted laser treatment of mono- and dual-species biofilms 158
7.1. Introduction 158
7.2. Materials and Methods 161
7.3. Results 166
7.4. Discussion 178
7.5. Conclusion 181
7.6. References 181
Chapter 8: Conclusion 185
8.1. Findings 185
8.2. Future works 187
Acknowledgments 190
Publications 191
Degree
Doctor
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대학원 > 의생명기계전기융합공학협동과정
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