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The preparation of a supramolecular nanocomposite containing BODIPY, tryptophan and gold nanoparticles capable of photosensitized generation of singlet oxygen is reported.

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The synthesis of water‐soluble chitosan nanocomposites incorporating BODIPY and the investigation of their photosensitization properties is reported. It was observed that the singlet oxygen generation capability of nanocomposites containing a mixture of BODIPY and iodine‐containing molecules are higher than that of the nanocomposites containing BODIPY alone. It is hypothesized that the supramolecular interactions between BODIPY and iodine‐containing molecules confined within the nanocomposites lead to the enhanced singlet oxygen generation.

A mesoporous magnetic nanohybrid functionalized with 14 wt% carbon nitride (CN) and loaded with curcumin (Cur) has been developed as a combination platform for photodynamic therapy and magnetic hyperthermia. CN-Cur complexes on the nanoparticle surface facilitate fast charge separation of hole-electrons under blue light irradiation and subsequent singlet oxygen generation. Cur release from the nanoparticle was significant only when exposed to both lysosomal pH (pH=5.2) and an alternating current magnetic field (AMF). The mesoporous magnetic carbon nitride (MMCN) caused a 350% increase in the level of intracellular ROS as compared to the light exposed untreated control group. The nanohybrid was non-hemolytic and found to be biocompatible with HUVEC cells at concentrations up to 360 µg/mL. A similar concentration under AMF exposure caused a localized temperature rise of 4.2 °C and resulted in a 60% reduction in C6 cell viability. The cancer cell death further increased up to 80% under sequential exposure to light and AMF. The combinatorial treatment exerted significant cytoskeletal and nuclear damage in the cancer cells as assessed by confocal microscopy. The nanohybrid also exhibited relaxivity of 88 mM-1 s-1 , imparting significant T2 weighted contrast to the cancer cells.

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Coupling of surface plasmons on metal nanoparticles with the electronic states of organic chromophores is known to result in hybrid states having unique photophysical properties. Previously, we had demonstrated that plasmon–molecule coupling in gold–BODIPY nanocomposites was effective for singlet oxygen production for photodynamic therapy (PDT). Herein, we show that gold nanoparticles can function as a matrix on which Förster resonance energy transfer (FRET) is facilitated between two electronically distinct BODIPY chromophores in a multichromophoric nanocomposite, which opens up radiative pathways, thereby making the nanocomposite fluorescent. Additionally, photoinduced hot electron transfer between BODIPY and gold allows for the efficient photosensitized generation of singlet oxygen. Our approach to achieving simultaneous FRET and plasmon–molecule interactions on gold nanoparticles is unique and hitherto unknown and makes the multichromophoric nanocomposite a potential candidate for photodynamic therapy and cell imaging.

Graphitic carbon nitride (also known as g-CN or g-C3N4) has the intrinsic ability to generate electron–hole pairs under visible light illumination, resulting in the generation of reactive oxygen species (ROS). We report g-CN quantum dots (g-CNQDs) as a standalone photodynamic transducer for imparting significant oxidative stress in glioma cells, manifested by the loss of mitochondrial membrane potential. With an optimized treatment time, visible light source, and exposure window, the photodynamic treatment with g-CNQDs could achieve ∼90% cancer cell death via apoptosis. The g-CNQDs, otherwise biocompatible with normal cells up to 5 mg/mL, showed ∼20% necrotic cancer cell death in the absence of light due to membrane damage induced by a charge shielding effect at the acidic pH prevailing in the tumor environment. Acute toxicity analysis in C57BL/6 mice with intravenously injected g-CNQDs at a 20 mg/kg dose showed no signs of inflammatory response or organ damage.