Low-Temperature Photothermal Therapy Based on Borneol-Containing Polymer-Modified MXene Nanosheets

Abstract

Noninvasive photothermal therapy (PTT) is an emerging strategy for eliminating multidrug-resistant (MDR) bacteria that achieve sterilization by generating temperatures above 50 °C; however, such a high temperature also causes collateral damage to healthy tissues. In this study, we developed a low-temperature PTT based on borneol-containing polymer-modified MXene nanosheets (BPM) with bacteria-targeting capabilities. BPM was fabricated through the electrostatic coassembly of negatively charged two-dimensional MXene nanosheets (2DM) and positively charged quaternized α-(+)-borneol-poly­(N,N-dimethyl ethyl methacrylate) (BPQ) polymers. Integrating BPQ with 2DM improved the stability of 2DM in physiological environments and enabled the bacterial membrane to be targeted due to the presence of a borneol group and the partially positive charge of BPQ. With the aid of near-infrared irradiation, BPM was able to effectively eliminate methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) through targeted photothermal hyperthermia. More importantly, BPM effectively eradicated more than 99.999% (>5 orders of magnitude) of MRSA by localized heating at a temperature that is safe for the human body (≤40 °C). Together, these findings suggest that BPM has good biocompatibility and that membrane-targeting low-temperature PTT could have great therapeutic potential against MDR infections.

Multifunctional Plasmon-Tunable Au Nanostars and Their Applications in Highly Efficient Photothermal Inactivation and Ultra-Sensitive SERS Detection

“…However, once S. aureus is treated with the A1 under laser irradiation, almost all of the S. aureus are killed. The possible bactericidal mechanism behind this is that the heat produced by Au NSs after NIR laser irradiation can cause the damage of membrane and denaturation of proteins and enzymes, which leads to bacterial death [ 74 , 75 ].…”

Constructing a self-healing injectable SABA/Borax/PDA@AgNPs hydrogel for synergistic low-temperature photothermal antibacterial therapy

“…9 To overcome this problem, low-temperature PTT (LT-PTT, ≤45 °C) has been considered as an expected modality to protect healthy tissues against high temperature injury. 10–13 Nevertheless, its efficiency is still restrained due to the relative low temperature during the treatment process. The introduction of an extra antibacterial method to realize combination therapy has become an important approach to boost bactericidal efficiency.…”

Bacteria-targeted photothermal therapy for combating drug-resistant bacterial infections

“…5,8 To address this issue, PTAs have been decorated with bacteria-targeting moieties, such as vancomycin (Van), anti-protein A IgG, aptamers and natural borneol-derived polymers. [9][10][11][12][13] MXenes are a new family of two-dimensional (2D) carbides and nitrides of transition metals with the general formula M n+1 X n T x (n = 1, 2 or 3), which are prepared by selective etching of the A element layer from the pristine M n+1 AX n phase. [14][15][16] Due to their intrinsic high conductivity, large specific surface area, hydrophilicity, and excellent near-infrared photothermal conversion capability, 2D MXene nanosheets (2DM) are widely used in energy storage, photocatalysis, environmental science and biomedical engineering.…”

“…5,8 To address this issue, PTAs have been decorated with bacteria-targeting moieties, such as vancomycin (Van), anti-protein A IgG, aptamers and natural borneol-derived polymers. 9–13…”

“…22 However, in physiological media, negatively charged 2DM rapidly aggregate and precipitate due to charge shielding. 13 Consequently, their bactericidal activity will be reduced due to the embedding of sharp edges and the reduction of light-to-heat conversion efficiency. Additionally, 2DM may also damage normal tissue cells as a result of their inability to target bacteria.…”