Fluorescein–Metal Hybrid Surfactant Conjugates as a Smart Material for Antimicrobial Photodynamic Therapy against Staphylococcus aureus

Abstract

Photodynamic therapy (PDT) has been extensively used as an effective alternative for the treatment of bacterial infection using photosensitizers (PSs) in the presence of appropriate light. However, the limitation in the effectiveness of PDT is because of the low yield of singlet oxygen from existing PSs because of their low solubility. Thus, we have developed a platform to enhance the solubility and the photodynamic activity of PSs against bacterial cells using metallosurfactants. Herein, we have used manganese metal-containing single-(MnC I) and doublechain metallosurfactants (MnC II) which show an interplay of electrostatic/hydrophobic interactions with fluorescein (FL) dye (as a PS) and when used in the presence of light enhances the PDT. These interactions play a significant role in enhancing the singlet oxygen generation efficiency of FL. MnC I and MnC II have shown good antimicrobial activity against Gram-positive Staphylococcus aureus (S. aureus) bacteria. More interestingly, these metallosurfactants when combined with FL significantly enhanced the affectivity against S. aureus, wherein 100% killing was achieved. As compared to experiments performed in the dark, the metallosurfactant, by enhancing the solubility of FL, increases the formation of singlet oxygen upon light irradiation and thus increases cell death. Therefore, the synergistic effect of FL (light toxicity) and metallosurfactants (dark toxicity) defined excellent reduction in the colony formation of bacteria. These results were corroborated through field-emission scanning electron microscopy and optical microscopy, where the rupturing of the cell wall of bacterial cells was observed during this therapy. Moreover, the binding of metallosurfactants to the genomic DNA of S. aureus was also evaluated by gel retardation analysis and UV−visible spectroscopy. The outcomes from this study will deliver formulations for PDT which can be used in clinical medical applications and cancer therapy in the future.

Efficient Photodynamic Therapy against Gram-Positive and Gram-Negative Bacteria Using Rose Bengal Encapsulated in Metallocatanionic Vesicles in the Presence of Visible Light

“…The chemical quenching method was employed for the quantitative analysis of singlet oxygen by utilizing UA, a buffer-soluble quencher. , Eosin was taken as a standard to determine Φ Δ 1 O 2 . Initially, the laser (alone) was irradiated on the buffer solution of UA and RB, and no change in UA and RB absorbance ruled out the effect of laser on these solutions (Figure S1).…”

“…aureus (MRSA; MTCC 290, Gram-positive) were received as a friendly gesture from Guru Jambheshwar University of Science and Technology, Hisar, India. The colony-forming unit (CFU) method was used to check the cytocidal effect by counting the living cells with and without dose. , The whole experiment was divided into two sections, one with light irradiation and the other without light, i.e., dark toxicity. The nutrient agar was used for E.…”

“…The colonyforming unit (CFU) method was used to check the cytocidal effect by counting the living cells with and without dose. 40,41 The whole experiment was divided into two sections, one with light irradiation and the other without light, i.e., dark toxicity. The nutrient agar was used for E. coli and mannitol salt agar was used for MRSA growth.…”

Advances and Perspective on Antimicrobial Nanomaterials for Biomedical Applications

“…A broad range of nanomaterials such as carbon and metal-based nanomaterials, nanocomposites, dendrimers, polymers, nanoemulsions, micelles, liposomes, etc. have been shown to exhibit a remarkable antimicrobial properties (Chauhan et al, 2019;Kaur et al, 2019;Garg et al, 2020;Garg et al, 2021;Makabenta et al, 2021;Singh et al, 2022). They are considered more capable as compared to their micro/macroscale counterparts in terms of inhibiting microbial growth (Zare et al, 2015).…”

Metallo-Liposomes Derived from the [Ru(bpy)3]2+ Complex as Nanocarriers of Therapeutic Agents

“…Metallosurfactants are amphiphilic molecules containing metal ions anchored in their structure. The metal ion is usually located at the head group of the molecule [1,2], although it can also be found in the hydrophobic tail [3,4] or acting as counter ion of the polar head group [5,6]. The presence of a metal ion in the surfactant confers the molecule characteristic properties for applications such as catalyst in heterogeneous processes or electron storage devices in photoredox processes.…”