Effect of Complexing with Silica Nanoparticles on the Phototoxicty of Some Photosensitisers

Evaluation of chlorophyll-loaded mesoporous silica nanoparticles for photodynamic therapy on cancer cell lines

Chlorophyll (Chl) is a promising natural photosensitizer (PS) in photodynamic treatment (PDT). Mesoporous silica nanoparticles (MSNs) were chosen to increase the effectiveness of PDT. This study aimed to evaluate the synergistic efficacy of chlorophyll-loaded mesoporous silica nanoparticles (Chl-MSNs) with photodynamic therapy (PDT) and to investigate their potential toxicity in HepG2, MDA-MB-231, and HSF cell lines. Chl-MSNs were prepared via the physical adsorption method. TEM, DLS, and zeta potential examined morphology, size, and surface characteristics. MSNs and Chl-MSNs were characterized using the same techniques. HPLC was used to assess the encapsulation efficiency. At pH 7.4, an in vitro release experiment of Chl-MSNs was performed. Chl, MSNs, and Chl-MSNs were applied to the three cell lines at different concentrations and subjected to red (650 nm) and blue (450-500 nm) lasers. MSNs and Chl-MSNs' sizes were 90.338 ± 38.49 nm and 123.84 ± 15.67 nm, respectively, as obtained by TEM; the hydrodynamic diameter for MSNs (93.69 ± 20.53 nm) and Chl-MSNs (212.95 ± 19.76 nm); and their zeta potential values are - 16.7 ± 2.19 mV and - 18.84 ± 1.40 mV. The encapsulation efficiency of Chl-MSNs was 70%. Chl-MSNs displayed no toxicity in dark conditions but showed excellent photostability under blue and red light exposure. Furthermore, using Chl over Chl-MSNs has a higher PDT efficiency than the tested cell lines. Chl-MSNs have the potential to be an effective delivery system. PDT proved to be an essential technique for cancer treatment. Blue laser is recommended over red laser with Chl and MSNs for destroying cancer cells.

Rose bengal-decorated rice husk-derived silica nanoparticles enhanced singlet oxygen generation for antimicrobial photodynamic inactivation

Rice husks are well known for their high silica content, and the RH-derived silica nanoparticles (RH NPs) are amorphous and biocompatible; therefore, they are suitable raw materials for biomedical applications. In this study, rose bengal-impregnated rice husk nanoparticles (RB-RH NPs) were prepared for their potential photosensitization and ¹O₂ generation as antimicrobial photodynamic inactivation. RB is a halogen-xanthene type's photosensitizer showing high singlet oxygen efficiency, and the superior photophysical properties are desirable for RB in the antimicrobial photodynamic inactivation of bacteria. To enhance the binding of anionic RB to RH NPs, we conducted cationization for the RH NPs using polyethyleneimine (PEI). The control of the RB adsorption state on cationic PEI-modified RH NPs was essential for RB RH-NP photosensitizers to obtain efficient ¹O₂ generation. Minimizing RB aggregation allowed highly efficient ¹O₂ production from RB-RH NPs at the molar ratio of RB with the PEI, X_RB/PEI. = 0.1. The RB-RH NPs have significant antimicrobial activity against Streptococcus mutans compared to free RB after white light irradiation. The RB-RH NP-based antimicrobial photodynamic inactivation can be employed effectively in treating Streptococcus mutans for dental applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10853-023-08194-z.

An insight into curcumin-based photosensitization as a promising and green food preservation technology

Consumer awareness on the side effects of chemical preservatives has increased the demand for natural preservation technologies. An efficient and sustainable alternative to current conventional preservation techniques should guarantee food safety and retain its quality with minimal side effects. Photosensitization, utilizing light and a natural photosensitizer, has been postulated as a viable and green alternative to the current conventional preservation techniques. The potential of curcumin as a natural photosensitizer is reviewed in this paper as a practical guide to develop a safe and effective decontamination tool for industrial use. The fundamentals of the photosensitization mechanism are discussed, with the main emphasis on the natural photosensitizer, curcumin, and its application to inactivate microorganisms as well as to enhance the shelf life of foods. Photosensitization has shown promising results in inactivating a wide spectrum of microorganisms with no reported microbial resistance due to its particular lethal mode of targeting nucleic acids. Curcumin as a natural photosensitizer has recently been investigated and demonstrated efficacy in decontamination and delaying spoilage. Moreover, studies have shown the beneficial impact of an appropriate encapsulation technique to enhance the cellular uptake of photosensitizers, and therefore, the phototoxicity. Further studies relating to improved delivery of natural photosensitizers with inherent poor solubility should be conducted. Also, detailed studies on various food products are warranted to better understand the impact of encapsulation on curcumin photophysical properties, photo-driven release mechanism, and nutritional and organoleptic properties of treated foods.

Photoinduced Dynamics and Toxicity of a Cancer Drug in Proximity of Inorganic Nanoparticles under Visible Light

Drug sensitization with various inorganic nanoparticles (NPs) has proved to be a promising and an emergent concept in the field of nanomedicine. Rose bengal (RB), a notable photosensitizer, triggers the formation of reactive oxygen species under green-light irradiation, and consequently, it induces cytotoxicity and cell death. In the present study, the effect of photoinduced dynamics of RB upon complexation with semiconductor zinc oxide NPs is explored. To accomplish this, we successfully synthesized nanohybrids of RB with ZnO NPs with a particle size of 24 nm and optically characterized them. The uniform size and integrity of the particles were confirmed by high-resolution transmission electron microscopy. UV/Vis absorption and steady-state fluorescence studies reveal the formation of the nanohybrids. ultrafast picosecond-resolved fluorescence studies of RB-ZnO nanohybrids demonstrate an efficient electron transfer from the photoexcited drug to the semiconductor NPs. Picosecond-resolved Förster resonance energy transfer from ZnO NPs to RB unravel the proximity of the drug to the semiconductor at the molecular level. The photoinduced ROS formation was monitored using a dichlorofluorescin oxidation assay, which is a conventional oxidative stress indicator. It is observed that the ROS generation under green light illumination is greater at low concentrations of RB-ZnO nanohybrids compared with free RB. Substantial photodynamic activity of the nanohybrids in bacterial and fungal cell lines validated the in vitro toxicity results. Furthermore, the cytotoxic effect of the nanohybrids in HeLa cells, which was monitored by MTT assay, is also noteworthy.