A Bacteria‐Responsive Porphyrin for Adaptable Photodynamic/Photothermal Therapy

Abstract

We report a cationic porphyrin 5,10,15,20‐tetrakis‐(4‐N‐methylpyridyl)‐porphyrin (TMPyP) that can respond to specific bacteria, followed by adaptable photodynamic/photothermal therapy processes. TMPyP could be reduced to phlorin by facultative anaerobes with a strong reducing ability such as E. coli and S. typhimurium in hypoxic environments, possessing strong NIR absorption and remarkable photothermal conversion capacity, thus demonstrating excellent antimicrobial activity (>99 %) by photothermal therapy. While in an aerobic environment with aerobic bacteria, TMPyP functioned as a typical photosensitizer that killed bacteria effectively (>99.9 %) by photodynamic therapy. By forming a host–guest complex with cucurbit[7]uril, the biocompatibility of TMPyP significantly improved. This kind of bacteria‐responsive porphyrin shows specificity and adaptivity in antimicrobial treatment and holds potential in non‐invasive treatments of bacterial infections.

Spatiotemporal Release of Reactive Oxygen Species and NO for Overcoming Biofilm Heterogeneity

“…Fe 3+ catalyzed Fenton‐like reactions turn localized hydrogen peroxide (H 2 O 2 ) into reactive oxygen species (ROS) and is potential for biofilm treatment by a ferroptosis pathway [20] . The space‐selective generation of ROS in the biofilm was further evaluated using 2,7‐dichlorodi‐hydrofluorescein diacetate (DCFH) [21] . As shown in Supporting Information, Figure S9c, after a 2 h reaction, fluorescence continuously intensified as the GA‐Fe MOF concentration increased in the filtrates of crushed biofilm (FoCB), while GA‐Fe MOF could hardly generate ⋅OH in the filtrates of cell culture medium (FoCCM).…”

“…[20] The space-selective generation of ROS in the biofilm was further evaluated using 2,7dichlorodi-hydrofluorescein diacetate (DCFH). [21] As shown in Supporting Information, Figure S9c, after a 2 h reaction, fluorescence continuously intensified as the GA-Fe MOF concentration increased in the filtrates of crushed biofilm (FoCB), while GA-Fe MOF could hardly generate * OH in the filtrates of cell culture medium (FoCCM). To further confirm the ability of NONOate/NP@GA-Fe MOF to catalyze ROS production, we conducted electron paramagnetic resonance (EPR) spin capture with 5,5-dimethyl-1pyrrolidine nitrogen oxide (DMPO, 500 mmol), which converts free radical intermediates into long-lived spin adducts.…”

Controlling Radical Polymerization with Biocatalysts

“…This progress in searching suitable oxidases for deoxygenation illustrates how identification and incorporation of more enzymes can enrich biocatalyst selection and better serve the purpose of green bio-RDRP. Along a similar line, bacterial reduction is one of the main functions employed in RDRP and most of the bacteria have a mild reduction potential (up to −350 mV vs standard hydrogen electrode). ,, Existing methods to improve the efficiency of bacterial electron transfer include introducing transmembrane and outer-membrane silver nanoparticles into bacteria or coating bacteria with conductive polymers, which may potentially be applied to bacterial-catalyzed RDRP. , Furthermore, identifying or engineering better reductive bacteria will be beneficial, which could potentially eliminate the use of redox mediators as in RAFT or enhance the activation rate of metal catalysts as in ATRP.…”

Recent nanotechnology-based strategies for interfering with the life cycle of bacterial biofilms

“…Specifically, some nanomaterials can simultaneously perform PDT and PTT for synergistic biofilm irradiation. 139,140…”

“…Specifically, some nanomaterials can simultaneously perform PDT and PTT for synergistic biofilm irradiation. 139,140 As an external trigger, NIR light can be utilized together with both endogenous stimuli 103,104,141 and other external triggers 109 to achieve a more precise control and to promote the antibiofilm effect.…”