Internal Light Sources-Mediated Photodynamic Therapy Nanoplatforms: Hope for the Resolution of the Traditional Penetration Problem

Photodynamic therapy (PDT) is an alternative cancer treatment technique with a noninvasive nature, high selectivity, and minimal adverse effects. The indispensable light source used in PDT is a critical factor in determining the energy conversion of photosensitizers (PSs). Traditional light sources are primarily concentrated in the visible light region, severely limiting their penetration depth and making them prone to scattering and absorption when applied to biological tissues. For that reason, its efficacy in treating deep-seated lesions is often inadequate. Self-exciting PDT, also known as auto-PDT (APDT), is an attractive option for circumventing the limited penetration depth of traditional PDT and has acquired significant attention. APDT employs depth-independent internal light sources to excite PSs through resonance or radiative energy transfer. APDT has considerable potential for treating deep-tissue malignancies. To facilitate many researchers' comprehension of the latest research progress in this field and inspire the emergence of more novel research results. This review introduces internal light generation mechanisms and characteristics and provides an overview of current research progress based on the recently reported APDT nanoplatforms. The current challenges and possible solutions of APDT nanoplatforms are also presented and provide insights for future research in the final section of this article.

A new multimodal magnetic nanozyme and a reusable peroxymonosulfate oxidation catalyst: Manganese oxide coated-monodisperse-porous and magnetic core-shell microspheres

Monodisperse-porous, polydopamine and manganese oxide coated, core-shell type, magnetic SiO2 (MagSiO2@PDA@MnO2) microspheres 6.4 μm in size were synthesized for the first time, using magnetic, monodisperse-porous SiO2 (MagSiO2) microspheres 6.2 μm in size as the starting material. MagSiO2 microspheres were obtained by a recently developed method namely "staged shape templated hydrolysis and condensation protocol". In the synthesis, MagSiO2 microspheres were consecutively coated by polydopamine (PDA) and then by a MnO2 layer in the aqueous medium. The pore volume and the specific surface area of monodisperse-porous MagSiO2@PDA@MnO2 microspheres were measured as 0.59 cm3 g-1 and 154 m2 g-1, respectively. Their Mn and Fe contents were determined as 66 ± 1 mg g-1 and 165 ± 5 mg g-1 respectively. MagSiO2@PDA@MnO2 microspheres exhibited multimodal enzyme mimetic behavior with highly superior catalase-like, oxidase-like and peroxidase-like activities. The effective production of singlet oxygen (1O2) and superoxide anion (O2-*) radicals in MagSiO2@PDA@MnO2-peroxymonosulfate (PMS) system was demonstrated by ESR spectroscopy. By evaluating this property, MagSiO2@PDA@MnO2 microspheres were tried as a reusable catalyst for dye removal via peroxymonosulfate (PMS) activation in batch experiments for the first time. The degradation runs were made with, rhodamine B (Rh B), methyl orange (MO) and methylene blue (MB) as the pollutant. The core-shell type design allowing the deposition of porous MnO2 layer onto a large surface area provided very fast, instant removals with all dyes, via both physical adsorption and degradation via PMS activation. In the reusability experiments, the removal yields of MO and Rh B decreased 1.8% and 8.9% over five consecutive runs in batch fashion. MagSiO2@PDA@MnO2 microspheres exhibited very good functional and structural stability in consecutive dye degradations. No significant change was observed in Fe content of microspheres while Mn content exhibited a decrease of 7.4% w/w over 5 consecutive degradation runs.

Peroxide-Simulating and GSH-Depleting Nanozyme for Enhanced Chemodynamic/Photodynamic Therapy via Induction of Multisource ROS

Reactive oxygen species (ROS) generation, using photodynamic therapy (PDT) and chemodynamic therapy (CDT), is a promising strategy for cancer treatment. However, the production of ROS in tumor cells is often limited by hypoxia, insufficient substrates, and high level of ROS scavengers in a tumor microenvironment, which seriously affects the efficacy of ROS-related tumor therapies. Herein, we report a lipid-supported manganese oxide nanozyme, MLP@DHA&Ce6, by decorating a MnO2 nano-shell on the liposome loaded with dihydroartemisinin (DHA) and photosensitizer Ce6 for generating multisource ROS to enhance cancer therapy. MLP@DHA&Ce6 can be accumulated in tumors and can release active components, Mn2+ ions, and O2. The conjugate generates ROS via nanozyme-catalyzed CDT using DHA as a substrate, PDT through Ce6, and the Fenton reaction catalyzed by Mn2+ ions. The production of O2 from MnO2 enhanced Ce6-mediated PDT under near-infrared light irradiation. Meanwhile, MLP@DHA&Ce6 showed prominent glutathione depletion, which allowed ROS to retain high activity in tumor cells. In addition, the release of Mn2+ ions and DHA in tumor cells induced ferroptosis. This multisource ROS generation and ferroptosis effect of MLP@DHA&Ce6 led to enhanced therapeutic effects in vivo.

Theranostics through Utilizing Cherenkov Radiation of Radioisotope Zr-89 with a Nanocomposite Combination of TiO2 and MnO2

Cherenkov radiation (CR) derived from the decay of diagnostic and therapeutic radionuclides is currently being studied by the scientific community to determine if these emissions can be harnessed for cancer detection and therapy. While Cherenkov luminescence imaging (CLI) has been studied in the preclinical and clinical settings, Cherenkov radiation-induced cancer therapy (CRICT) is a relatively new area of research that harnesses the emitted photons to kill cancer cells through free radical generation and DNA damage. Nanoparticles seem well suited for developing a theranostic platform that would allow researchers to visualize therapy delivery and also generate the reactive oxygen species necessary to kill cancer cells. Herein, we report the preparation of an ⁸⁹Zr-TiO₂-MnO₂ nanocomposite that incorporates transferrin onto the nanoparticle surface to enhance cancer cell growth inhibition. The incorporation of the positron emission tomography (PET) radioisotope ⁸⁹Zr (half-life: 3.3 days) allowed for the detection of the nanoparticle using PET and for the creation of Cherenkov emissions that interacted with the nanoparticle surface to generate free radicals for therapy delivery. After preparation, these systems were observed to be stable in various media and provided excellent tumor growth control after being intratumorally injected into mice bearing CT-26 tumors. These results demonstrate that a therapeutically efficient CRICT platform can be generated using commercially available and affordable materials.

Manganese-based hollow nanoplatforms for MR imaging-guided cancer therapies

Theranostic nanoplatforms integrating diagnostic and therapeutic functions have received considerable attention in the past decade. Among them, hollow manganese (Mn)-based nanoplatforms are superior since they combine the advantages of hollow structures and the intrinsic theranostic features of Mn²⁺. Specifically, the hollow cavity can encapsulate a variety of small-molecule drugs, such as chemotherapeutic agents, photosensitizers and photothermal agents, for chemotherapy, photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. After degradation in the tumor microenvironment (TME), the released Mn²⁺ is able to act simultaneously as a magnetic resonance (MR) imaging contrast agent (CA) and as a Fenton-like agent for chemodynamic therapy (CDT). More importantly, synergistic treatment outcomes can be realized by reasonable and optimized design of the hollow nanosystems. This review summarizes various Mn-based hollow nanoplatforms, including hollow Mn_xO_y, hollow matrix-supported Mn_xO_y, hollow Mn-doped nanoparticles, hollow Mn complex-based nanoparticles, hollow Mn-cobalt (Co)-based nanoparticles, and hollow Mn-iron (Fe)-based nanoparticles, for MR imaging-guided cancer therapies. Finally, we discuss the potential obstacles and perspectives of these hollow Mn-based nanotheranostics for translational applications.

Targeted carbon monoxide delivery combined with chemodynamic, chemotherapeutic and photothermal therapies for enhanced antitumor efficacy

Polydopamine-coated hollow mesoporous copper sulfide loaded with DHA and CO-releasing molecules selectively delivered DHA and CO to tumor cells under 808 nm light irradiation, demonstrating multimodal synergistic antitumor efficacy.

Advances in FePt-involved nano-system design and application for bioeffect and biosafety

The rapid development and wide application of nanomaterial-involved theranostic agents have drawn surging attention for improving the living standard of humankind and healthcare conditions. In this review, recent developments in the design, synthesis, biocompatibility evaluation and potential nanomedicine applications of FePt-involved nano-systems are summarized, especially for cancer theranostic and biological molecule detection. The in vivo multi-model imaging capability is discussed in detail, including magnetic resonance imaging and computed tomography. Furthermore, we highlight the significant achievements of various FePt-involved nanotherapeutics for cancer treatment, such as drug delivery, chemodynamic therapy, photodynamic therapy, radiotherapy and immunotherapy. In addition, a series of FePt-involved nanocomposites are also applied for biological molecule detection, such as H₂O₂, glucose and naked-eye detection of cancer cells. Ultimately, we also summarize the challenges and prospects of FePt-involved nano-systems in nanocatalytic medicine. This review is expected to give a general pattern for the development of FePt-involved nano-systems in the field of nanocatalytic medicine and analytical determination.