Honeycomb-Satellite Structured pH/H2O2-Responsive Degradable Nanoplatform for Efficient Photodynamic Therapy and Multimodal Imaging

Tumor microenvironment responsive mesoporous silica nanoparticles for dual delivery of doxorubicin and chemodynamic therapy (CDT) agent

We engineered a tumor microenvironment-triggered MSN-based anti-cancer nanocarrier for simultaneous delivery of DOX and chemodynamic agent.

NIR Light-Degradable Antimony Nanoparticle-Based Drug-Delivery Nanosystem for Synergistic Chemo-Photothermal Therapy in Vitro

A novel drug-delivery nanosystem based on near-infrared (NIR) light-degradable antimony nanoparticles (AMNP) have been developed for synergistic chemo-phototherapy in vitro. The monodispersed AMNP were synthesized by using a simple and cost-effective method. Positively charged doxorubicin hydrochloride (DOX) was loaded onto the negatively charged surface of AMNP via electrostatic interaction and finally modified by polyacrylic acid (PAA) to enhance biocompatibility. Under NIR (808 nm) laser irradiation of the AMNP-DOX-PAA nanosystem, not only was high photothermal conversion efficiency of AMNP achieved but also pH-dependent DOX release was enhanced due to laser-induced hyperthermia. As a consequence, almost all of the HeLa cells (around 97%) were killed because of the combined effects of chemotherapy and photothermal therapy. More interestingly, AMNP showed very fast (about 10 min) laser-induced degradation that may help to minimize long-term toxicity after therapy by using same-wavelength NIR laser irradiation (808 nm). Computational total energy calculations and molecular dynamics simulations based on density functional theory (DFT) suggest that the NIR laser irradiation induces a photothermally activated reaction on the surface of AMNP in water, which can lead to surface degradation via the formation of Sb-H bonds first and then Sb-OH bonds upon further increase of temperature. This work demonstrates a simple platform that has potential applications for synergistic and highly effective chemo-photothermal therapy based on photodegradable nanoparticles.

Manganese Oxide Nanoparticles As MRI Contrast Agents In Tumor Multimodal Imaging And Therapy

Contrast agents (CAs) play a crucial role in high-quality magnetic resonance imaging (MRI) applications. At present, as a result of the Gd-based CAs which are associated with renal fibrosis as well as the inherent dark imaging characteristics of superparamagnetic iron oxide nanoparticles, Mn-based CAs which have a good biocompatibility and bright images are considered ideal for MRI. In addition, manganese oxide nanoparticles (MONs, such as MnO, MnO2, Mn3O4, and MnOx) have attracted attention as T1-weighted magnetic resonance CAs due to the short circulation time of Mn(II) ion chelate and the size-controlled circulation time of colloidal nanoparticles. In this review, recent advances in the use of MONs as MRI contrast agents for tumor detection and diagnosis are reported, as are the advances in in vivo toxicity, distribution and tumor microenvironment-responsive enhanced tumor chemotherapy and radiotherapy as well as photothermal and photodynamic therapies.

Tumor self-responsive upconversion nanomedicines for theranostic applications

To date, malignant tumors continue to be the most lethal disease, causing more than 8.2 million deaths worldwide each year. In recent years, nanostructures based on rare-earth upconversion luminescent nanoparticles have shown significant advantages in the integration of multimodal imaging and therapy. Compared with normal tissues, the tumor microenvironment (TME) exhibits unique characteristics including high interstitial fluid pressure, abnormal blood vessels, a hypoxic and slightly acidic environment, and high levels of glutathione (GSH) and hydrogen peroxide (H2O2). According to these characteristics, increasing attention in the antitumor field has been given to designing nanomedicines with specific responses to the TME based on rare-earth upconversion nanoparticles (UCNPs) and to achieving efficient tumor diagnosis and treatment under the premise of reducing side effects. Nevertheless, a review that systematically summarizes TME-responsive upconversion nanomedicines (UCNMs) for realizing tumor self-enhanced theranostics has not been published to date. In this review, we summarize the recent progress made in UCNP-based nanotherapeutics by highlighting the increasingly developing trend of TME-responsive UCNMs. The general characteristics of the TME are introduced in detail and their utilization in designing TME-responsive UCNMs is systematically discussed. Based on NIR light-excited optical imaging, we discuss the superiority of UCNMs when applied in tumor theranostics with an emphasis on how to use them to realize TME-mediated multimodal imaging-guided therapy.

Single NIR Laser-Activated Multifunctional Nanoparticles for Cascaded Photothermal and Oxygen-Independent Photodynamic Therapy

Inconvenient dual-laser irradiation and tumor hypoxic environment as well as limited judgment of treating region have impeded the development of combined photothermal and photodynamic therapies (PTT and PDT). Herein, Bi₂Se₃@AIPH nanoparticles (NPs) are facilely developed to overcome these problems. Through a one-step method, free radical generator (AIPH) and phase transition material (lauric acid, LA, 44-46 °C) are encapsulated in hollow bismuth selenide nanoparticles (Bi₂Se₃ NPs). Under a single 808-nm laser irradiation at the tumor area, hyperthermia produced by Bi₂Se₃ not only directly leads to cell death, but also promotes AIPH release by melting LA and triggers free radical generation, which could further eradicate tumor cells in hypoxic environments. Moreover, Bi₂Se₃ with high X-ray attenuation coefficient endows the NPs with high computed tomography (CT) imaging capability, which is important for treating area determination. The results exhibit that Bi₂Se₃@AIPH NPs possesses 31.2% photothermal conversion efficiency for enhanced PTT, ideal free radical generation for oxygen-independent PDT, and 37.77 HU mL mg^-1 X-ray attenuation coefficient for CT imaging with high quality. Most importantly, the tumor growth inhibition rate by synergistic PTT, PDT, and following immunotherapy is 99.6%, and even one tumor disappears completely, which demonstrates excellent cascaded synergistic effect of Bi₂Se₃@AIPH NPs for the tumor therapy.

Activatable Hybrid Polyphosphazene-AuNP Nanoprobe for ROS Detection by Bimodal PA/CT Imaging

Overproduction of reactive oxygen species (ROS) is often related to inflammation or cancer and can cause tissue damage. Probes that have been previously reported to image ROS typically rely on imaging techniques that have low depth penetration in tissue, thus limiting their use to superficial disease sites. We report herein a novel formulation of hybrid nanogels loaded with gold nanoparticles (AuNP) to produce contrast for computed tomography (CT) and photoacoustics (PA), both being deep-tissue imaging techniques. The polyphosphazene polymer has been designed to selectively degrade upon ROS exposure, which triggers a switch-off of the PA signal by AuNP disassembly. This ROS-triggered degradation of the nanoprobes leads to a significant decrease in the PA contrast, thus allowing ratiometric ROS imaging by comparing the PA to CT signal. Furthermore, ROS imaging using these nanoprobes was applied to an in vitro model of inflammation, that is, LPS-stimulated macrophages, where ROS-triggered disassembly of the nanoprobe was confirmed via reduction of the PA signal. In summary, these hybrid nanoprobes are a novel responsive imaging agent that have the potential to image ROS overproduction by comparing PA to CT contrast.

Facile Phototherapeutic Nanoplatform by Integrating a Multifunctional Polymer and MnO2 for Enhancing Tumor Synergistic Therapy

Recent studies indicate that the synergistic phototherapy (SPT) process can simultaneously generate heat for photothermal therapy (PTT) and singlet oxygen (¹ O₂ ) for photodynamic therapy (PDT) to overcome the recurrence of tumors. However, the hypoxic environment in tumors seriously limits the therapeutic effect of the oxygen-dependent PDT, leading to the domination of PTT in the SPT process. Therefore, it is urgent to develop a novel SPT platform for overcoming hypoxia in tumors and improving the therapeutic effect of both PTT and PDT. In this work, a novel phototherapeutic platform based on a nanocomposite of aza-BODIPY/manganese dioxide (MnO₂ ) is developed via simple electrostatic self-assembly. In this design, MnO₂ nanosheets, which could produce heat and catalyze endogenous hydrogen peroxide (H₂ O₂ ) to generate oxygen, are prepared as a nanocarrier. After being coated with the as-prepared water-soluble aza-BODIPY-based polymer (PPAIB), the obtained MnO₂ @PPAIB performs as a smart phototherapeutic agent for enhancing the efficiency of both PTT and PDT. More importantly, compared to PPAIB, MnO₂ @PPAIB generates more heat and reactive oxygen species to realize the enhanced therapy effects of PTT and PDT. Hence, this work provides a new method to enhance the therapeutic efficacy of SPT by using a polymer/MnO₂ nanoplatform to improve the oxygen concentration and produce more heat.

Fluorescence-enhanced covalent organic framework nanosystem for tumor imaging and photothermal therapy

Fluorescent dyes, as a key factor in fluorescence imaging, usually exhibit a low signal-to-noise ratio (SNR) due to the limited loading capacities of delivery systems (usually less than 10.0 wt%) and their uncontrolled release. Herein, we developed a type of pH-responsive nanoplatform (MnO2/ZnCOF@Au&BSA) based on a zinc porphyrin covalent organic framework (COF), in which the zinc porphyrin (ZnPor) loading rate is 22.5 wt%. At pH = 7.4, the interlinked ZnPor in the assembly state did not show a fluorescence signal ("off" state). Together with the pH-triggered disintegration of ZnCOF in tumor cells (pH = 5.5), the scattered ZnPor displayed an obvious fluorescence signal recovery ("on" state). Simultaneously, the shed BSA-coated gold nanoparticles ingeniously caused the fluorescence signal to be further amplified through the metal-enhanced fluorescence effect, which was about 3.0-fold higher in vivo than in the free ZnPor group. Combined with the excellent photothermal therapy effect by the nanoplatform itself with the tumor inhibition rate of 79.5%, this nanosystem effectively solves the problem of low loading capacities and imaging SNR by traditional delivery systems, and successfully develops the potential of COFs for fluorescence imaging, achieving the purpose of integration of diagnosis and treatment.

Nanoparticle-Based Paramagnetic Contrast Agents for Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive medical imaging modality that is routinely used in clinics, providing anatomical information with micron resolution, soft tissue contrast, and deep penetration. Exogenous contrast agents increase image contrast by shortening longitudinal (T 1) and transversal (T 2) relaxation times. Most of the T 1 agents used in clinical MRI are based on paramagnetic lanthanide complexes (largely Gd-based). In moving to translatable formats of reduced toxicity, greater chemical stability, longer circulation times, higher contrast, more controlled functionalisation and additional imaging modalities, considerable effort has been applied to the development of nanoparticles bearing paramagnetic ions. This review summarises the most relevant examples in the synthesis and biomedical applications of paramagnetic nanoparticles as contrast agents for MRI and multimodal imaging. It includes the most recent developments in the field of production of agents with high relaxivities, which are key for effective contrast enhancement, exemplified through clinically relevant examples.

Photothermal-Controlled Generation of Alkyl Radical from Organic Nanoparticles for Tumor Treatment

The therapeutic properties of light are well known for photodynamic or photothermal therapy, which could cause irreversible photodamage to tumor tissues. Although photodynamic therapy (PDT) has been proved in the clinic, the efficacy is not satisfactory because of complicated tumor microenvironments. For example, the hypoxia in solid tumor has a negative effect on the generation of singlet oxygen. To address the hypoxia issues in PDT, leveraging alkyl radical is an available option due to the oxygen-independent feature. In this work, a new kind of organic nanoparticles (tripolyphosphate (TPP)-NN NPs) from porphyrin and radical initiator is developed. Under near-infrared light irradiation, TPP-NN NPs will split and release alkyl radical, which could induce obvious cytotoxicity both in normal and hypoxia environment. The photothermal-controlled generation of alkyl radical could significantly inhibit the growth of cervical cancer and show ignorable systemic toxicity. This activatable radical therapy opens up new possibilities for the application of PDT in hypoxia condition.