Magnetic-Responsive Photosensitizer Nanoplatform for Optimized Inactivation of Dental Caries-Related Biofilms: Technology Development and Proof of Principle

Abstract

Conventional antibiotic therapies for biofilm-trigged oral diseases are becoming less efficient due to the emergence of antibiotic-resistant bacterial strains. Antimicrobial photodynamic therapy (aPDT) is hampered by restricted access to bacterial communities embedded within the dense extracellular matrix of mature biofilms. Herein, a versatile photosensitizer nanoplatform (named MagTBO) was designed to overcome this obstacle by integrating toluidine-blue ortho (TBO) photosensitizer and superparamagnetic iron oxide nanoparticles (SPIONs) via a microemulsion method. In this study, we reported the preparation, characterization, and application of MagTBO for aPDT. In the presence of an external magnetic field, the MagTBO microemulsion can be driven and penetrate deep sites inside the biofilms, resulting in an improved photodynamic disinfection effect compared to using TBO alone. Besides, the obtained MagTBO microemulsions revealed excellent water solubility and stability over time, enhanced the aPDT performance against S. mutans and saliva-derived multispecies biofilms, and improved the TBO’s biocompatibility. Such results demonstrate a proof-of-principle for using microemulsion as a delivery vehicle and magnetic field as a navigation approach to intensify the antibacterial action of currently available photosensitizers, leading to efficient modulation of pathogenic oral biofilms.

Applications of Antimicrobial Photodynamic Therapy against Bacterial Biofilms

“…However, to the extent of our literature search, no studies of MHT in combination with PDT have been reported. When an external magnetic field was used for targeting of chlorin e6-laden and mesoporous silica-capped iron oxide magnetic nanoparticles during aPDT [ 135 ], it caused the magnetic nanoparticles to move deep into the biofilm, without an alternating magnetic field as in MHT [ 136 ]. A nanoconjugate consisting of superparamagnetic iron oxide nanoparticles capped with the photosensitizer curcumin showed magneto-thermal conversion upon application of an alternating magnetic field and excellent PDT effects upon irradiation with blue light, eradicating planktonic Staphylococcus aureus .…”

“…The combinations with photothermal therapy are also limited by light penetration depth to skin wound therapeutic applications [ 126 ]. The low interest in combinations with MHT may be attributed to the low biofilm weakening efficacy of magnetic hyperthermia [ 136 ] and the high cost of the applicator [ 138 ]. Although a number of devices are now commercially available for the combination with CAP, the combination is still limited to skin and low depth wound infections [ 34 , 35 , 36 , 37 ].…”

Metal and Metal Oxide Nanomaterials for Fighting Planktonic Bacteria and Biofilms: A Review Emphasizing on Mechanistic Aspects

“…In the action of an external magnetic field, the nanorobot-loaded photosensitizer entered the deep region of the biofilm. The effect of the photodynamic therapy was improved by the direct interaction between the photosensitizer and the bacteria ( Figure 10 d) [ 106 ]. It has been reported that EPS elimination may result from the degradation of EPS components.…”

Dental Materials for Oral Microbiota Dysbiosis: An Update

“…A. Balhaddad et al constructed a nanoplatform by assembling TBO and magnetic Fe 3 O 4 . In addition to the photodynamic antibacterial property of Ce 6, Fe 3 O 4 equipped the nanoplatform with the capability to penetrate deep sites under external magnetic forces, resulting in an improved disinfection effect (Balhaddad et al, 2021).…”