Low-Temperature Photothermal Therapy: Strategies and Applications

Abstract

Although photothermal therapy (PTT) with the assistance of nanotechnology has been considered as an indispensable strategy in the biomedical field, it still encounters some severe problems that need to be solved. Excessive heat can induce treated cells to develop thermal resistance, and thus, the efficacy of PTT may be dramatically decreased. In the meantime, the uncontrollable diffusion of heat can pose a threat to the surrounding healthy tissues. Recently, low-temperature PTT (also known as mild PTT or mild-temperature PTT) has demonstrated its remarkable capacity of conquering these obstacles and has shown excellent performance in bacterial elimination, wound healing, and cancer treatments. Herein, we summarize the recently proposed strategies for achieving low-temperature PTT based on nanomaterials and introduce the synthesis, characteristics, and applications of these nanoplatforms. Additionally, the combination of PTT and other therapeutic modalities for defeating cancers and the synergistic cancer therapeutic effect of the combined treatments are discussed. Finally, the current limitations and future directions are proposed for inspiring more researchers to make contributions to promoting low-temperature PTT toward more successful preclinical and clinical disease treatments.

Cyclic RGD functionalized PLGA nanoparticles loaded with noncovalent complex of indocyanine green with urokinase for synergistic thrombolysis

“…Following irradiation for 10 min, the temperature of 5 μg/ml sample rose to approximately 48°C and reached 55°C at the concentration of 10 μg/ml solution. Studies have shown that high-temperature exposure poses thermal damage to surrounding healthy tissues and potentially induces local inflammation due to thermal diffusion, and mild-temperature (42–45°C) photothermal treatment has been proven to achieve ideal therapeutic performance ( Huang et al, 2020 ; Xiao et al, 2020 ; Yi et al, 2021 ). Accordingly, the concentration of ICG was set at 5 μg/ml in our study.…”

Microbial resistance to nanotechnologies: An important but understudied consideration using antimicrobial nanotechnologies in orthopaedic implants

“…By reducing the functional temperature to below 48 °C, along with the synergistic effects of other antibacterial agents such as metal nanoparticles, NO, antibiotics, and other bactericidal modalities [ [205] , [206] , [207] ], satisfactory therapeutic outcome can be retained while the potential threat to the nearby tissues can be maximally alleviated [ 208 ]. Of note is that at temperature >48 °C, even a short-term treatment (4–6 min) can lead to a significant damage to cellular proteins and DNA [ 208 , 209 ], thus low-temperature PTT in comparison to the high-temperature modality is preferred as it preserves the protective functions of the host immune system against microbial. Regardless of current laboratory success in applying PTT to combat resistant bacterial infections, clinical use of PTT often suffers from insufficient penetration into deep tissue to remove bacteria therefrom [ 210 ].…”

Heat Treatment Promotes Ubiquitin-Mediated Proteolysis of SARS-CoV-2 RNA Polymerase and Decreases Viral Load

“…Heat treatment in the form of sauna or hot bath is a facile, widely accessible, and inexpensive approach practiced widely for therapeutic and recreational purposes, making it a quickly scalable measure for emerging new variants. In fact, mild heat treatment has already been applied in the management of other diseases like cancer, wound, and microbial infection [ 20 , 21 ]. Our recent work also demonstrated heat treatment as an efficient approach to destabilize thermal-sensitive oncogenic proteins in acute promyelocytic leukemia patients with clinical benefits [ 12 ].…”