Surface plasmon-photosensitizer resonance coupling: an enhanced singlet oxygen production platform for broad-spectrum photodynamic inactivation of bacteria

Abstract

A general platform to improve singlet oxygen productionviaresonance coupling between surface plasmon and photosensitizers, and for broad-spectrum photodynamic inactivation of bacteria.

Light‐Harvesting Photosensitizers for Photodynamic Inactivation of Bacteria under Both Visible and Near‐Infrared Excitations

“…As shown in Figure , the riboflavin‐containing hybrid has a much higher singlet oxygen production than free riboflavin or PDDA‐coated AgNPs, separately, under 446 nm excitation, with an enhancement factor of ∼14.6. This observation is consistent with our previous work involving a different photosensitizing molecule . More strikingly, significant singlet oxygen production can also be observed from the same hybrid under 880 nm (near‐infrared) excitation, where free riboflavin molecules do not produce singlet oxygen.…”

“…We have previously demonstrated that plasmon‐photosensitizer hybrids display potent efficacy in broad‐spectrum PDI of bacteria, including gram‐positive, gram‐negative, and even drug‐resistant bacteria . Inspired by the broadened excitation profiles of these plasmon‐photosensitizer hybrids observed spectroscopically, we examined their efficacy in inactivating bacteria upon the irradiation with near‐infrared and visible light, respectively (Figures S3–S5).…”

“…The synthesis of silver‐mesoporous silica core–shell nanoparticles (Ag@mSiO 2 ) is the same as previously reported, using silver nitrate as the precursor, formaldehyde as the reducing agent, CTAB as the stabilizer and template, TEOS as the silica source, and sodium hydroxide as the catalyst . In a typical run, CTAB (20 mg) was dissolved in a solution containing 9.8 mL of water and 0.24 mL of 0.5 m NaOH.…”

“…[17] We have recently reported that plasmon photosensitizers can serve as ag eneral platform for the third-generation photosensitizers, where strong resonance coupling between the absorption of photosensitizers and the localized surfacep lasmon of metal nanostructures can greatly enhancet he singlet oxygen productiona nd improvet he PDI efficacya gainst bacteria. [18] Other studies have also suggested that light-harvesting is ak ey element for the design of the third-generation photosensitizers. [19][20][21][22][23][24][25] Here we demonstrate the light-harvesting capability of plasmon-photosensitizer hybrids, especially in the near-infrared spectralr egion, where free photosensitizing molecules do not otherwise absorb.…”

Using photochemistry to understand and control the production of reactive oxygen species in biological environments

“…This approach proved to be successful, and both Ag and Au MNPs coated with mesoporous silica shells loaded with photosensitizers exhibit an enhancement of 1 O 2 production. [135,136] A potential drawback of this strategy is that 1 O 2 has to diffuse outside the silica matrix in order to have any potential use. [137] To alleviate this difficulty, an alternate approach would be to covalently attach the photosensitizer onto the MNPs surface.…”