Search Results (4)

Photodynamic therapy (PDT) is a minimally invasive treatment for several diseases. It combines light energy with a photosensitizer (PS) to destroy the targeted cells or tissues. A PS itself is a non-toxic substance, but it becomes toxic to the target cells through the activation of light at a specific wavelength. There are some limitations of PDT, although it has been used in clinical studies for a long time. Two-photon excitation (TPE) and upconversion (UC) for PDT have been recently developed. A TPE nanoparticle-based PS combines the advantages of TPE and nanotechnology that has emerged as an attractive therapeutic agent for near-infrared red (NIR) light-excited PDT, whilst UC is also used for the NIR light-triggered drug release, activation of ‘caged’ imaging, or therapeutic molecules during PDT process for the diagnosis, imaging, and treatment of cancers. Methods: Nine electronic databases were searched, including WanFang Data, PubMed, Science Direct, Scopus, Web of Science, Springer Link, SciFinder, and China National Knowledge Infrastructure (CNKI), without any language constraints. TPE and UCNP were evaluated to determine if they had different effects from PDT on cancers. All eligible studies were analyzed and summarized in this review. Results: TPE-PDT and UCNP-PDT have a high cell or tissue penetration ability through the excitation of NIR light to activate PS molecules. This is much better than the conventional PDT induced by visible or ultraviolet (UV) light. These studies showed a greater PDT efficacy, which was determined by enhanced generation of reactive oxygen species (ROS) and reduced cell viability, as well as inhibited abnormal cell growth for the treatment of cancers. Conclusions: Conventional PDT involves Type I and Type II reactions for the generation of ROS in the treatment of cancer cells, but there are some limitations. Recently, TPE-PDT and UCNP-PDT have been developed to overcome these problems with the help of nanotechnology in in vitro and in vivo studies. Full article

Background: In addition to their great optical properties, nanodiamonds (NDs) have recently proved useful for two-photon-excited photodynamic therapy (TPE-PDT) applications. Indeed, they are able to produce reactive oxygen species (ROS) directly upon two-photon excitation but not with one-photon excitation; Methods: Fluorescent NDs (FNDs) with a 100 nm diameter and detonation NDs (DNDs) of 30 nm were compared. In order to use the gems for cancer-cell theranostics, they were encapsulated in a bis(triethoxysilyl)ethylene-based (ENE) periodic mesoporous organosilica (PMO) shell, and the surface of the formed nanoparticles (NPs) was modified by the direct grafting of polyethylene glycol (PEG) and amino groups using PEG-hexyltriethoxysilane and aminoundecyltriethoxysilane during the sol–gel process. The NPs’ phototoxicity and interaction with MDA-MB-231 breast cancer cells were evaluated afterwards; Results: Transmission electronic microscopy images showed the formation of core–shell NPs. Infrared spectra and zeta-potential measurements confirmed the grafting of PEG and NH₂ groups. The encapsulation of the NDs allowed for the imaging of cancer cells with NDs and for the performance of TPE-PDT of MDA-MB-231 cancer cells with significant mortality. Conclusions: Multifunctional ND@PMO core–shell nanosystems were successfully prepared. The NPs demonstrated high biocompatibility and TPE-PDT efficiency in vitro in the cancer cell model. Such systems hold good potential for two-photon-excited PDT applications. Full article

Nitrogen doping and amino group functionalization through chemical modification lead to strong electron donation. Applying these processes to a large π-conjugated system of graphene quantum dot (GQD)-based materials as electron donors increases the charge transfer efficiency of nitrogen-doped amino acid-functionalized GQDs (amino-N-GQDs), resulting in enhanced two-photon absorption, post-two-photon excitation (TPE) stability, TPE cross-sections, and two-photon luminescence through the radiative pathway when the lifetime decreases and the quantum yield increases. Additionally, it leads to the generation of reactive oxygen species through two-photon photodynamic therapy (PDT). The sorted amino-N-GQDs prepared in this study exhibited excitation-wavelength-independent two-photon luminescence in the near-infrared region through TPE in the near-infrared-II region. The increase in size resulted in size-dependent photochemical and electrochemical efficacy, increased photoluminescence quantum yield, and efficient two-photon PDT. Therefore, the sorted amino-N-GQDs can be applicable as two-photon contrast probes to track and localize analytes in in-depth two-photon imaging executed in a biological environment along with two-photon PDT to eliminate infectious or multidrug-resistant microbes. Full article

Driven by their distinctive physiological activities, biological properties and unique theranostic modalities, silicon nanoparticles (SiNPs) are one of the promising materials for the development of novel multifunctional nanoplatforms for biomedical applications. In this work, we assessed the possibility to use laser-synthesized Si NPs as photosensitizers in two-photon excited photodynamic therapy (TPE-PDT) modality. Herein, we used an easy strategy to synthesize ultraclean and monodispersed SiNPs using laser ablation and fragmentation sequences of silicon wafer in aqueous solution, which prevent any specific purification step. Structural analysis revealed the spherical shape of the nanoparticles with a narrow size distribution centered at the mean size diameter of 62 nm ± 0.42 nm, while the negative surface charge of −40 ± 0.3 mV ensured a great stability without sedimentation over a long period of time. In vitro studies on human cancer cell lines (breast and liver) and healthy cells revealed their low cytotoxicity without any light stimulus and their therapeutic potential under TPE-PDT mode at 900 nm with a promising cell death of 45% in case of MCF-7 breast cancer cells, as a consequence of intracellular reactive oxygen species release. Their luminescence emission inside the cells was clearly observed at UV-Vis region. Compared to Si nanoparticles synthesized via chemical routes, which are often linked to additional modules with photochemical and photobiological properties to boost photodynamic effect, laser-synthesized SiNPs exhibit promising intrinsic therapeutic and imaging properties to develop advanced strategy in nanomedicine field. Full article