Photodynamic therapy (PDT) involves the cellular uptake of a photosensitizer (PS) combined with oxygen molecules and light at a specific wavelength to be able to trigger cancer cell death via the apoptosis pathway, which is less harmful and has less inflammatory side effect than necrosis. However, the traditional PDT treatment has two main deficiencies: the dark toxicity of the PS and the poor selectivity of the cellular uptake of PS between the target cells and normal tissues. In this work, methylene blue (MB), a known effective PS, combined with Au nanoparticles (NPs) was prepared using an intermolecular interaction between a polystyrene-alt-maleic acid (PSMA) layer on the Au NPs and MB. The Au@polymer/MB NPs produced a high quantum yield of singlet oxygen molecules, over 50% as much as that of free MB, when they were excited by a dark red light source at 660 nm, but without significant dark toxicity. Furthermore, transferrin (Tf) was conjugated on the Au@polymer/MB NPs via an EDC/NHS reaction to enhance the selectivity to HeLa cells compared to 3T3 fibroblasts. With a hand-held single laser treatment (32 mW/cm) for 4 min, the new Au@polymer/MB-Tf NPs showed a 2-fold enhancement of PDT efficiency toward HeLa cells over the use of free MB at 4 times dosage. Cellular staining examinations showed that the HeLa cells reacted with Au@polymer/MB-Tf NPs and the 660 nm light excitation triggered PDT, which caused the cells to undergo apoptosis ("programmed" cell death). We propose that applying this therapeutic Au@polymer/MB-Tf nanoagent is facile and safe for delivery and cancer cell targeting to simultaneously minimize side effects and accomplish a significant enhancement in photodynamic therapeutic efficiency toward next-generation nanomedicine development.

Extensive efforts have been devoted to the development of a new biophotonic system using near infrared (NIR) nano-agents for non-invasive cancer diagnosis and therapy. Here, we developed a simple synthesis reaction of ligands, hydrazine, and iron(ii) chloride to fabricate Fe3O4 cluster-structured nanoparticles (CNPs) with interesting NIR photonics and high magnetization (Ms: 98.3 emu g(-1) and proton relaxivity r2: 234.6 mM(-1) s(-1)). These Fe3O4 CNPs exhibited optical absorption and reflection over all wavelengths, showing a U-shape absorption band with a low absorbance at a range of 750-950 nm and a progressive evolution in the second near infrared region. Strengthening of the scattering effect by incubating Fe3O4 CNPs with HeLa cells was observed when optical contrast enhancement was performed in an optical coherence tomography (OCT) microscope system with a laser light source at 860 nm. Using a 1064 nm laser at a low power density (380 mW cm(-2)) to excite the Fe3O4 CNPs (375 ppm[Fe]) led to a rise in the water temperature from 25 °C to 58 °C within 10 min. Finally, we present the first example of magnetomotive OCT cellular imaging combined with enhanced photothermal therapy using Fe3O4 CNPs and applying a magnetic field, which is promising for preclinical and clinical trials in the future.

A PCR provides not only valuable genetic information that enables precise differential disease diagnosis but also quantitative data to assess various clinical states. We report the successful integration of novel dual-mode magnetic Fe 3 O 4 nanoclusters that deliver photothermal conversion. The clusters can be excited with pulsed laser light for precision thermal cycle modulation to develop an ultrafast quantitative PCR system. Traditional PCR heats and cools the sample from outside the PCR tube; the heat needs to pass through the heat block, tube wall and transfer to the DNA through water molecules. In contrast, our system uses nanoparticles inside the liquid phase as numerous 'nanoheaters'; thus the thermal transfer between particles and adjacent water or DNA molecules becomes extremely efficient because of proximity at the molecular level. Moreover, the defective mitochondrial DNA from cybrid cell lines of a patient with chronic progressive external ophthalmoplegia syndrome, a mitochondrial disease, was efficaciously detected. The system has a simple design, is extremely energy efficient and is faster than traditional qPCR. Our finding provides new insight into rapid and accurate quantitative diagnostics for future point-of-care applications.