Efficacy, biocompatibility and degradability of carbon nanoparticles for photothermal therapy of lung cancer

Aim: To investigate near infrared-induced phototoxicity toward lung cancer cells, and the biodegradability and effect on immune cells of glucose-derived carbon nanoparticles (CNPs). Methods: The human A549 lung adenocarcinoma cell line was used as a model to study the phototoxicity of CNPs. The biodegradability and the effect on immune cells was demonstrated in primary human neutrophils and macrophages. Results: Near infrared-activated CNPs elicited rapid cell death, characterized by the elevation of heat shock proteins and the induction of DNA damage. CNPs were found to be noncytotoxic toward primary human macrophages and were susceptible to biodegradation when cocultured with human neutrophils. Conclusions: Our results identify CNPs as promising platforms for photothermal therapy of lung cancer.

Potential of Photodynamic Therapy Based on Sugar-Conjugated Photosensitizers

In 2015, the Japanese health insurance approved the use of a second-generation photodynamic therapy (PDT) using talaporfin sodium (TS); however, its cancer cell selectivity and antitumor effects of TS PDT are not comprehensive. The Warburg effect describes the elevated rate of glycolysis in cancer cells, despite the presence of sufficient oxygen. Because cancer cells absorb considerable amounts of glucose, they are visible using positron emission tomography (PET). We developed a third-generation PDT based on the Warburg effect by synthesizing novel photosensitizers (PSs) in the form of sugar-conjugated chlorins. Glucose-conjugated (tetrafluorophenyl) chlorin (G-chlorin) PDT revealed significantly stronger antitumor effects than TS PDT and induced immunogenic cell death (ICD). ICD induced by PDT enhances cancer immunity, and a combination therapy of PDT and immune checkpoint blockers is expected to synergize antitumor effects. Mannose-conjugated (tetrafluorophenyl) chlorin (M-chlorin) PDT, which targets cancer cells and tumor-associated macrophages (TAMs), also shows strong antitumor effects. Finally, we synthesized a glucose-conjugated chlorin e6 (SC-N003HP) that showed 10,000-50,000 times stronger antitumor effects than TS (IC₅₀) in vitro, and it was rapidly metabolized and excreted. In this review, we discuss the potential and the future of next-generation cancer cell-selective PDT and describe three types of sugar-conjugated PSs expected to be clinically developed in the future.

Hand-ground fullerene-nanodiamond composite for photosensitized water treatment and photodynamic cancer therapy

The unique capability of fullerene (C₆₀) to absorb light and generate reactive oxygen species (ROS) has been extensively studied for photosensitized water treatment and cancer therapy. Various material synthesis strategies have been proposed in parallel to overcome its intrinsic hydrophobicity and to enhance availability in water and physiological media. We present here a strikingly simple approach to make C₆₀ available to these applications by hand-grinding dry C₆₀ powder with nanodiamond (ND) using a mortar and pestle. The resulting ND-C₆₀ composite was found to form a stable aqueous colloidal suspension and efficiently drive photosensitized production of ROS under visible light illumination. ND-C₆₀ rapidly adsorbed and oxidized organic contaminants by photogenerated ROS. In the experiments for photodynamic cancer therapy, ND-C₆₀ was internalized by cancer cells and induced cell apoptosis without noticeable toxicity. Treatment of tumor-bearing mice with ND-C₆₀ and light irradiation resulted in tumor shrinkage and prolonged survival time.

Perfluorocarbon@Porphyrin Nanoparticles for Tumor Hypoxia Relief to Enhance Photodynamic Therapy against Liver Metastasis of Colon Cancer

Photodynamic therapy (PDT) shows great promise for the treatment of colon cancer. However, practically, it is a great challenge to use a nanocarrier for the codelivery of both the photosensitizer and oxygen to improve PDT against PDT-induced hypoxia, which is closely related to tumor metastasis. Hence, an effective strategy was proposed to develop an oxygen self-supplemented PDT nanocarrier based on the ultrasonic dispersion of perfluorooctyl bromide (PFOB) liquid into the preformed porphyrin grafted lipid (PGL) nanoparticles (NPs) with high porphyrin loading content of 38.5%, followed by entrapping oxygen. Interestingly, the orderly arranging mode of porphyrins and alkyl chains in PGL NPs not only guarantees a high efficacy of singlet oxygen generation but also reduces fluorescence loss of porphyrins to enable PGL NPs to be highly fluorescent. More importantly, PFOB liquid was stabilized inside PGL NPs with an ultrahigh loading content of 98.15% due to the strong hydrophobic interaction between PGL and PFOB molecules, facilitating efficient oxygen delivery. Both in vitro and in vivo results demonstrated that the obtained O₂@PFOB@PGL NPs could act as a prominent oxygen reservoir and effectively replenish oxygen into the hypoxic tumors with no need for external stimulation, conducive to augmented singlet oxygen generation, hypoxia relief, and subsequent downregulation of COX-2 expression. As a result, the use of O₂@PFOB@PGL NPs for hypoxia relief dramatically inhibits tumor growth and liver metastasis in an HT-29 colon cancer mouse model. In addition, the O₂@PFOB@PGL NPs could serve as a bimodal contrast agent to enhance fluorescence and CT imaging, visualizing nanoparticle accumulation to guide the subsequent laser irradiation for precise PDT.

Near-Infrared Light-Harvesting Fullerene-Based Nanoparticles for Promoted Synergetic Tumor Phototheranostics

A synergetic phototheranostic system, combining diagnostic photo-imaging and phototherapies [such as photothermal therapy and photodynamic therapy (PDT)], shows great potential in today's tumor precise therapy. Herein, we fabricate near-infrared (NIR) light-harvesting fullerene-based nanoparticles (DAF NPs) for photoacoustic (PA) imaging-guided synergetic tumor photothermal and PDT. The fullerene derivatives (DAF) absorbing in the NIR region have been synthesized by conjugating NIR-absorbing antenna with fullerene. In addition, DAF NPs with good biocompatibility have been fabricated via a nanoprecipitation approach. The as-prepared DAF NPs can accumulate and generate PA signals around the tumor site 6 h post injection via enhanced permeability and retention effect in vivo. More importantly, the DAF NPs exhibit better reactive oxygen species and heat generation efficacy compared with fullerene and antenna nanoparticles (DA NPs), respectively. Further in vitro and in vivo studies demonstrate that DAF NPs can effectively inhibit tumor growth through synergetic photodynamic and photothermal therapies, which provides a new sight of photosensitizer design for enhanced cancer phototheranostics.

Organo metal halide perovskites effectively photosensitize the production of singlet oxygen (1Δg)

Using the steady state and time resolved NIR emission and specific chemical trapping techniques, we show for the first time that metal halide perovskite quantum dots can effectively generate singlet oxygen with a quantum yield of up to 0.34, the highest among nano semiconductor/nano metal singlet oxygen photosensitizers. The mechanism is concluded to be due to energy transfer from triplet excitons to molecular oxygen.

Photosensitizers for Photodynamic Therapy

As an emerging clinical modality for cancer treatment, photodynamic therapy (PDT) takes advantage of the cytotoxic activity of reactive oxygen species (ROS) that are generated by light irradiating photosensitizers (PSs) in the presence of oxygen (O₂ ). However, further advancements including tumor selectivity and ROS generation efficiency are still required. Substantial efforts are devoted to design and synthesize smart PSs with optimized properties for achieving a desirable therapeutic efficacy. This review summarizes the recent progress in developing intelligent PSs for efficient PDT, ranging from single molecules to delicate nanomaterials. The strategies to improve ROS generation through optimizing photoinduced electron transfer and energy transfer processes of PSs are highlighted. Moreover, the approaches that combine PDT with other therapeutics (e.g., chemotherapy, photothermal therapy, and radiotherapy) and the targeted delivery in cancer cells or tumor tissue are introduced. The main challenges for the clinical application of PSs are also discussed.

Tumour-targeting photosensitisers for one- and two-photon activated photodynamic therapy

Efficient receptor-mediated delivery of a folate-targeted photosensitiser to kill cancer cells following two-photon excitation in the near-infrared is demonstrated.

Formation of C60 fullerene-bonded-CNTs using radio frequency plasma

Hybrid CNTs-C₆₀ (CNBs) were successfully synthesized using radio frequency plasma for the first time. It would be an efficient and easy method to build a special structure with nanotube junctions.

C60@lysozyme: a new photosensitizing agent for photodynamic therapy

C₆₀@lysozyme showed significant visible light-induced singlet oxygen generation in a physiological environment, indicating the potential of this hybrid as an agent for photodynamic therapy.