An Engineered Nanocomplex with Photodynamic and Photothermal Synergistic Properties for Cancer Treatment.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are promising therapeutic methods for cancer treatment; however, as single modality therapies, either PDT or PTT is still limited in its success rate. A dual application of both PDT and PTT, in a combined protocol, has gained immense interest. In this study, gold nanoparticles (AuNPs) were conjugated with a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, designed as nanotherapeutic agents that can activate a dual photodynamic/photothermal therapy in SH-SY5Y human neuroblastoma cells. The AuNP-mTHPC complex is biocompatible, soluble, and photostable. PDT efficiency is high because of immediate reactive oxygen species (ROS) production upon mTHPC activation by the 650-nm laser, which decreased mitochondrial membrane potential (∆ψm). Likewise, the AuNP-mTHPC complex is used as a photoabsorbing (PTA) agent for PTT, due to efficient plasmon absorption and excellent photothermal conversion characteristics of AuNPs under laser irradiation at 532 nm. Under the laser irradiation of a PDT/PTT combination, a twofold phototoxicity outcome follows, compared to PDT-only or PTT-only treatment. This indicates that PDT and PTT have synergistic effects together as a combined therapeutic method. Our study aimed at applying the AuNP-mTHPC approach as a potential treatment of cancer in the biomedical field.

meso-Tetrahydroxyphenylchlorin-Conjugated Gold Nanoparticles as a Tool To Improve Photodynamic Therapy.

Photodynamic therapy (PDT) is a promising therapeutic modality for cancer. However, current protocols using bare drugs suffer from several limitations that impede its beneficial clinical effects. Here, we introduce a new approach for an efficient PDT treatment. It involves conjugating a PDT agent, meso-tetrahydroxyphenylchlorin (mTHPC) photosensitizer, to gold nanoparticles (AuNPs) that serve as carriers for the drug. AuNPs have a number of characteristics that make them highly suitable to function as drug carriers: they are biocompatible, serve as biomarkers, and function as contrast agents in vitro and in vivo. We synthesized AuNPs and covalently conjugated the mTHPC drug molecules through a linker. The resultant functional complex, AuNP-mTHPC, is a stable, soluble compound. SH-SY5Y human neuroblastoma cells were incubated with the complex, showing possible administration of higher doses of drug when conjugated to the AuNPs. Then cells were irradiated with a laser beam at 650 nm to mimic the PDT procedure. Our study shows higher rates of cell death in cells incubated with the AuNP-mTHPC complex compared to the incubation with the free drug. Using the new complex may form the basis for a better PDT strategy for a wide range of cancers.

Low temperature, template-free route to nickel thin films and nanowires.

In this manuscript, we report on the elaboration of nickel thin films, isolated clusters and nanowires on silicon, glass and polymers by a low temperature deposition technique. The process is based on the thermal decomposition of Ni (η(4)-C(8)H(12))(2) at temperatures as low as 80 °C, which exclusively yields metallic Ni and a volatile by-product. The low temperature of the process makes it compatible with most of the substrates, even polymers and organic layers. Several deposition techniques are explored, among them spin coating of the organometallic complex in solution, which allows controlling nickel film thickness down to several nanometers. The density of the film can be varied by the speed of the spin coater with the formation of nanowires being observed for an optimized speed. The nanowires form a network of parallel lines on silicon and the phenomenon will be discussed as a selective dewetting of the organometallic precursor. All samples are fully characterized by SEM, EDS, cross-sectional HRTEM, ellipsometry, AFM, MFM and SQUID magnetic measurements.