Synergistic Photodynamic and Photothermal Antibacterial Therapy Based on a Conjugated Polymer Nanoparticle-Doped Hydrogel

Abstract

Herein, we have developed a composite antibacterial hydrogel with photodynamic therapy (PDT) and photothermal therapy (PTT) antibacterial capabilities, triggered by white light and NIR light irradiation. A water-insoluble conjugated polymer (PDPP) with photothermal ability was prepared into nanoparticles by the nanoprecipitation method, and the cell-penetrating peptide TAT was grafted on the surface of the nanoparticles. Based on our previous work that developed a hybrid hydrogel with an enhanced PDT effect from polyisocyanide (PIC) hydrogel and cationic conjugated polythiophene (PMNT), PDPP nanoparticles (CPNs-TAT) with photothermal ability are introduced to realize the synergistic antibacterial effect of PDT and PTT. Using the PIC hydrogel to combine PIC and CPNs-TAT has the following advantages. First, the PIC hydrogel can regulate the aggregation state of PMNT, making it better dispersed and improving its capacity of reactive oxygen species (ROS) production. Second, CPNs-TAT can be uniformly dispersed in the PIC hybrid, thereby avoiding the toxicity caused by too high local concentration, achieving a uniform increase in system temperature, and enhancing the therapeutic effect of PTT. Third, the PIC hybrid has the synergistic treatment effect of PDT and PTT. The PIC hybrid intelligently regulates its antibacterial ability through white light and NIR light, which can be used in the white light and NIR light areas. When irradiated with white light and NIR light sequentially, synergistic PDT and PTT exhibit stronger antibacterial ability than PDT or PTT alone. The combination of two antibacterial methods realizes the dual-control antibacterial hydrogel of PDT and PTT and provides an antibacterial mode based on PIC hybrids. Therefore, the PIC hybrids are promising as an antibacterial excipient for clinical wounds.

A Review on Hydrogels with Photothermal Effect in Wound Healing and Bone Tissue Engineering

“…Hydrogels with a porous network have been used widely in biomedicine. One of the strategies to solve aggregation is that nanomaterials can be dispersed effectively in hydrogels [ 62 , 63 ]. In addition, nanomaterials can be surface-modified and covalently cross-linked or non-covalently cross-linked with hydrogels [ 64 , 65 ].…”

Light‐Activated Conjugated Polymers for Antibacterial Photodynamic and Photothermal Therapy

“…[ 20 ] Conjugated polymers containing diketopyrrolopyrrole (DPP) with NIR absorption, low fluorescence quantum yield, and good photothermal conversion have been used for PTT (Figure 4). [ 9,23,58,96 ] Although the association of different conjugated polymers with complementary optical properties has generated nanoparticles that can achieve aPTT and aPDT against bacteria, [ 23,96 ] a single conjugated polymer with donor–acceptor structure based on thiophene (electron‐rich) and benzothiadiazole and diketopyrrolopyrrole (electron‐deficient) (referred to as PTDBD) was able to generate sufficient ROS and heat to inactivate bacteria through both mechanisms while requiring only one light source (808 nm laser) (Figure 4). [ 81 ]…”

“…[ 95 ] In addition to constituting particle preparations, conjugated polymers could also tackle bacteria while embedded in a elastomer matrix [ 27 ] and in hydrogels. [ 28,96 ] To form CPNs, hydrophilic conjugated polymers have been synthesized [ 104 ] or they have been functionalized with cationic side chains for water solubility. [ 19,22,24,81,97 ] Alternatively, hydrophobic conjugated polymers have been encapsulated in a matrix of amphiphilic molecules, such as disodium salt 3,30‐dithiodipropionic acid (SDPA), [ 25 ] poly(styrene‐ co ‐maleic anhydride) (PSMA), [ 23 ] and 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐ N ‐[methoxy(polyethyleneglycol)] (DSPE‐PEG 2000 ).…”

“…[ 19,22,24,81,97 ] Alternatively, hydrophobic conjugated polymers have been encapsulated in a matrix of amphiphilic molecules, such as disodium salt 3,30‐dithiodipropionic acid (SDPA), [ 25 ] poly(styrene‐ co ‐maleic anhydride) (PSMA), [ 23 ] and 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐ N ‐[methoxy(polyethyleneglycol)] (DSPE‐PEG 2000 ). [ 9,96 ] Cationic surfactants, such as cetyltrimethylammonium bromide (CTAB), have also been used to prepare cationic CPNs. [ 82 ] CPNs can be generated by facile production methods, which have an important effect in the CPNs’ optical properties, all of which have been recently summarized elsewhere.…”

Semiflexible polymer scaffolds: an overview of conjugation strategies

“…254,255 Xing and coworkers used the scaffolding capacity of the PICP backbone to induce conformational changes in water-soluble conducting polymers (polythiophenes and polyfluorenes). [256][257][258] The stretched conformations red shifts the absorption band of the polymers, which allows the formation of reactive oxygen species (ROS) after irradiation with red light. The hydride forms an efficient photodynamic antimicrobial material with activity towards various pathogens.…”