Polymer–Upconverting Nanoparticle Hybrid Micelles for Enhanced Synergistic Chemo–Photodynamic Therapy: Effects of Emission–Absorption Spectral Match

Multifunctional Nanoplatform for Single NIR Laser-Regulated Efficient PDT/PTT/Chemotherapy

The combination of phototherapy and chemotherapy with superior advantages is a promising strategy for cancer therapy. However, combination therapy is generally regulated by two different wavelengths of light or other stimuli, which results in complex operations and inevitable systemic side effects, even affecting therapeutic efficacy. Herein, we design a signal NIR light-regulated nanoplatform via the self-assembly process of reactive oxygen species (ROS)-sensitive prodrug (DTD), human serum albumin (HSA), and IR780 for combined photothermal/photodynamic therapy and chemotherapy. Upon 808 nm laser irradiation, IR780 in nanoparticles generates abundant ROS and a significant photothermal effect to achieve photothermal/photodynamic therapy. Meanwhile, the generating ROS further cleans up the thioketal link to release DOX for chemotherapy. Hence, signal NIR light can effectively control the process of combination therapy. In vivo and in vitro experiment results demonstrate that the multifunctional nanoparticles exhibit excellent antitumor efficacy via the combination of phototherapy and chemotherapy controlled by a signal NIR laser. Overall, the signal NIR light-regulated nanoparticles with combination therapy performance provide a versatile platform for enhancing antitumor efficacy.

Overcoming challenges in cancer treatment: Nano-enabled photodynamic therapy as a viable solution

Cancer presents a formidable challenge, necessitating innovative therapies that maximize effectiveness while minimizing harm to healthy tissues. Nanotechnology has emerged as a transformative force in cancer treatment, particularly through nano-enabled photodynamic therapy (NE-PDT), which leverages precise and targeted interventions. NE-PDT capitalizes on photosensitizers activated by light to generate reactive oxygen species (ROS) that initiate apoptotic pathways in cancer cells. Nanoparticle enhancements optimize this process, improving drug delivery, selectivity, and ROS production within tumors. This review dissects NE-PDT's mechanistic framework, showcasing its potential to harness apoptosis as a potent tool in cancer therapy. Furthermore, the review explores the synergy between NE-PDT and complementary treatments like chemotherapy, immunotherapy, and targeted therapies, highlighting the potential to amplify apoptotic responses, enhance immune recognition of cancer cells, and inhibit resistance mechanisms. Preclinical and clinical advancements in NE-PDT demonstrate its efficacy across various cancer types. Challenges in translating NE-PDT into clinical practice are also addressed, emphasizing the need for optimizing nanoparticle design, refining dosimetry, and ensuring long-term safety. Ultimately, NE-PDT represents a promising approach in cancer therapy, utilizing the intricate mechanisms of apoptosis to address therapeutic hurdles. The review underscores the importance of understanding the interplay between nanoparticles, ROS generation, and apoptotic pathways, contributing to a deeper comprehension of cancer biology and novel therapeutic strategies. As interdisciplinary collaborations continue to thrive, NE-PDT offers hope for effective and targeted cancer interventions, where apoptosis manipulation becomes central to conquering cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Mitochondria-Targeting Upconversion Nanoparticles@MOF for Multiple-Enhanced Photodynamic Therapy in Hypoxic Tumor

The effect of photodynamic therapy (PDT) is severely limited by tumor hypoxia and the short half-life of reactive oxygen species (ROS). Herein, we constructed a near-infrared (NIR) light-regulated PDT nanoplatform (TPP-UCNPs@MOF-Pt) consisting of an upconversion nanoparticle (UCNP) core and porphyrin-based metal-organic framework (MOF) shell with platinum nanoparticles (PtNPs) and a mitochondria-targeting triphenylphosphine (TPP) group on the surface. TPP-UCNPs@MOF-Pt could effectively relieve the tumor hypoxia by converting intracellular H₂O₂ to oxygen (O₂) and elevated the ROS level to enhance PDT efficacy under NIR light irradiation. In addition, the mitochondria-targeting TPP-UCNPs@MOF-Pt was localized on the mitochondria, leading to severe depolarization of the mitochondrial membrane and activation of the apoptotic pathway, further amplifying the therapeutic efficacy. In vitro and in vivo experiments demonstrated that the greatly enhanced photodynamic therapeutic efficacy of TPP-UCNPs@MOF-Pt was achieved by combining relief of tumor hypoxia with mitochondrial targeting and NIR activation. This study provides a promising strategy for construction of an MOF-based multifunctional nanoplatform to address the current limitations of PDT treatment for hypoxic tumors.

Doxorubicin-loaded micelles in tumor cell-specific chemotherapy

Nanomedicine is a field that combines biology and engineering to improve disease treatment, particularly in cancer therapy. One of the promising techniques utilized in this area is the use of micelles, which are nanoscale delivery systems that are known for their simple preparation, high biocompatibility, small particle size, and the ability to be functionalized. A commonly employed chemotherapy drug, Doxorubicin (DOX), is an effective inhibitor of topoisomerase II that prevents DNA replication in cancer cells. However, its efficacy is frequently limited by resistance resulting from various factors, including increased activity of drug efflux transporters, heightened oncogenic factors, and lack of targeted delivery. This review aims to highlight the potential of micelles as new nanocarriers for delivering DOX and to examine the challenges involved with employing chemotherapy to treat cancer. Micelles that respond to changes in pH, redox, and light are known as stimuli-responsive micelles, which can improve the targeted delivery of DOX and its cytotoxicity by facilitating its uptake in tumor cells. Additionally, micelles can be utilized to administer a combination of DOX and other drugs and genes to overcome drug resistance mechanisms and improve tumor suppression. Furthermore, micelles can be used in phototherapy, both photodynamic and photothermal, to promote cell death and increase DOX sensitivity in human cancers. Finally, the alteration of micelle surfaces with ligands can further enhance their targeted delivery for cancer suppression.

NIR regulated upconversion nanoparticles@metal-organic framework composite hydrogel dressing with catalase-like performance and enhanced antibacterial efficacy for accelerating wound healing

Developing a hydrogel dressing with excellent antibacterial efficacy for accelerating wound healing is high desirable in clinical applications. In this work, NIR regulated metal-organic framework composite hydrogel dressing was constructed for enhanced antibacterial efficacy and accelerated wound healing via the compounding between hydrogel and UCNPs@ZrMOF-Pt nanoparticles. The visible light emitted from upconvertion nanoparticles (UCNPs) activated porphyrin based metal-organic framework (MOF) in composite hydrogel to generate ¹O₂ for photodynamic antibacterial therapy under NIR laser irradiation. Moreover, the UCNPs@ZrMOF-Pt in composite hydrogel with catalase-like performance could effectively convert the high concentration H₂O₂ in wound to abundant O₂, which relieved the hypoxic in infected wound. Thus, the photodynamic antibacterial efficacy was remarkably enhanced, leading to accelerate the wound healing. This work presented a novel strategy for high efficient antibacterial therapy and accelerated wound healing.

Core-Coordinated Elliptic Polymer Nanoparticles Loading Copper(II) and Chlorambucil for Cooperative Chemodynamic/Chemotherapy

Chemodynamic therapy (CDT) reflects an innovative cancer treatment modality; however, to enhance its relatively low therapeutic efficiency, rational combination with extra therapeutic modes is highly appreciated. Here, core-coordinated amphiphilic, elliptic polymer nanoparticles (Cu/CBL-POEGEA NPs) are constructed via the self-assembly of a glutathione (GSH)-responsive polymer-drug conjugate, bearing side-chain acylthiourea (ATU) motifs which behave as ligands capable of coordinating Cu(II), such a design is featured by combined chemo (CT)/CDT with dual GSH depletion collectively triggered by the Cu(II) reduction reaction and disulfide bond breakage. To do so, an amphiphilic random copolymer poly[oligo(ethylene glycol)ethyl acrylate-co-thiourea] [P(OEGEA-co-ATU)] is synthesized, followed by conjugation of chlorambucil (CBL) to ATU motifs linked via a disulfide bond, thus yielding the targeted P[OEGEA-co-(ATU-g-CBL)]. In such a system, hydrophilic POEGEA serves as the biocompatible section and ATU motifs coordinate Cu(II), resulting in core-coordinated elliptic Cu/CBL-POEGEA NPs. Benefitting from the GSH-induced reduction reaction, Cu(II) is converted into Cu(I) and subsequently react with endogenous H₂O₂ to create ^•OH, realizing GSH-depletion-promoted CDT. Additionally, the disulfide bond endows GSH-responsive CBL release and provokes further GSH decline, finally realizing combined CDT/CT toward enhancing antitumor outcomes, and in vitro as well as in vivo studies indeed reveal remarkable efficacy. Such a system can provide valuable advantages to create novel nanomedicines toward cascade antitumor therapy.

NIR-Triggered Generation of Reactive Oxygen Species and Photodynamic Therapy Based on Mesoporous Silica-Coated LiYF4 Upconverting Nanoparticles

To date, the increase in reactive oxygen species (ROS) production for effectual photodynamic therapy (PDT) treatment still remains challenging. In this study, a facile and effective approach is utilized to coat mesoporous silica (mSiO₂) shell on the ligand-free upconversion nanoparticles (UCNPs) based on the LiYF₄ host material. Two kinds of mesoporous silica-coated UCNPs (UCNP@mSiO₂) that display green emission (doped with Ho³⁺) and red emission (doped with Er³⁺), respectively, were successfully synthesized and well characterized. Three photosensitizers (PSs), merocyanine 540 (MC 540), rose bengal (RB), and chlorin e6 (Ce6), with the function of absorption of green or red emission, were selected and loaded into the mSiO₂ shell of both UCNP@mSiO₂ nanomaterials. A comprehensive study for the three UCNP@mSiO₂/PS donor/acceptor pairs was performed to investigate the efficacy of fluorescence resonance energy transfer (FRET), ROS generation, and in vitro PDT using a MCF-7 cell line. ROS generation detection showed that as compared to the oleate-capped and ligand-free UCNP/PS pairs, the UCNP@mSiO₂/PS nanocarrier system demonstrated more pronounced ROS generation due to the UCNP@mSiO₂ nanoparticles in close vicinity to PS molecules and a higher loading capacity of the photosensitizer. As a result, the three LiYF₄ UCNP@mSiO₂/PS nanoplatforms displayed more prominent therapeutic efficacies in PDT by using in vitro cytotoxicity tests.

Phytoglycogen Encapsulation of Lanthanide-Based Nanoparticles as an Optical Imaging Platform with Therapeutic Potential

Lanthanide-based upconverting nanoparticles (UCNPs) are largely sought-after for biomedical applications ranging from bioimaging to therapy. A straightforward strategy is proposed here using the naturally sourced polymer phytoglycogen to coencapsulate UCNPs with hydrophobic photosensitizers as an optical imaging platform and light-induced therapeutic agents. The resulting multifunctional sub-micrometer-sized luminescent beads are shown to be cytocompatible as carrier materials, which encourages the assessment of their potential in biomedical applications. The loading of UCNPs of various elemental compositions enables multicolor hyperspectral imaging of the UCNP-loaded beads, endowing these materials with the potential to serve as luminescent tags for multiplexed imaging or simultaneous detection of different moieties under near-infrared (NIR) excitation. Coencapsulation of UCNPs and Rose Bengal opens the door for potential application of these microcarriers for collagen crosslinking. Alternatively, coloading UCNPs with Chlorin e6 enables NIR-light triggered generation of reactive oxygen species. Overall, the developed encapsulation methodology offers a straightforward and noncytotoxic strategy yielding water-dispersible UCNPs while preserving their bright and color-tunable upconversion emission that would allow them to fulfill their potential as multifunctional platforms for biomedical applications.

Self-Assembly of Upconversion Nanoparticles Based Materials and Their Emerging Applications

In the past few decades, significant progress of the conventional upconversion nanoparticles (UCNPs) based nanoplatform has been achieved in many fields, and with the development of nanoscience and nanotechnology, more and more complex situations need a UCNPs based nanoplatform having multifunctions for specific multimodal or multiplexed applications. Through self-assembly, different UCNPs or UCNPs with other materials could be combined together within an entity. It is more like an ideal UCNPs nanoplatform, a unique system with the properties defined by its individual components as well as by the morphology of the composite. Various designs can show their different desired properties depending on the application situation. This review provides a complete summary on the optimization of the synthesis method for the recently designed UCNPs assemblies and summarizes various applications, including dual-modality cell imaging, molecular delivery, detection, and programmed control therapy. The challenges and limitations the UCNPs assembly faces and the potential solutions in this field are also presented.

Combinatorial Therapeutic Approaches with Nanomaterial-Based Photodynamic Cancer Therapy

Photodynamic therapy (PDT), in which a light source is used in combination with a photosensitizer to induce local cell death, has shown great promise in therapeutically targeting primary tumors with negligible toxicity and minimal invasiveness. However, numerous studies have shown that noninvasive PDT alone is not sufficient to completely ablate tumors in deep tissues, due to its inherent shortcomings. Therefore, depending on the characteristics and type of tumor, PDT can be combined with surgery, radiotherapy, immunomodulators, chemotherapy, and/or targeted therapy, preferably in a patient-tailored manner. Nanoparticles are attractive delivery vehicles that can overcome the shortcomings of traditional photosensitizers, as well as enable the codelivery of multiple therapeutic drugs in a spatiotemporally controlled manner. Nanotechnology-based combination strategies have provided inspiration to improve the anticancer effects of PDT. Here, we briefly introduce the mechanism of PDT and summarize the photosensitizers that have been tested preclinically for various cancer types and clinically approved for cancer treatment. Moreover, we discuss the current challenges facing the combination of PDT and multiple cancer treatment options, and we highlight the opportunities of nanoparticle-based PDT in cancer therapies.

Spatially confined photoexcitation with triplet-triplet annihilation upconversion

Two-photon absorption (TPA) has been widely used in confocal microscopy, photo-initiated three-dimensional (3D) polymerization, and 3D-micro/nanofabrication. These applications are based on the spatial confinement of the TPA excitation, due to the quadratic excitation power dependency of the excitation. However, an expensive and high-power femtosecond (fs) pulsed laser has to be used. Herein, we show a new technique as a promising alternative to the TPA to achieve spatially confined excitation, but no fs laser and TPA dyes are required. This new spatially confined excitation with a continuous wave laser is based on triplet-triplet-annihilation upconversion. The potential of the new technique was demonstrated by spatially confined photopolymerization.

808 nm Near-Infrared Light-Triggered Payload Release from Green Light-Responsive Donor-Acceptor Stenhouse Adducts Polymer-Coated Upconversion Nanoparticles

Owing to deep activation in biotissues and enhanced targeting efficiency, developing photoresponsive polymer-upconversion nanoparticles (PP-UCNPs) nanovectors has witnessed rapid growth in the past decade. However, up to date, all developed nanovectors require high-order photon processes to initiate the release of cargos. The photodamage caused by high-power near-infrared laser light may be a critical obstacle to their clinical application. Here, for the first time, by leveraging absorption-emission spectral matching between donor-acceptor Stenhouse adducts (DASA) PP and UCNPs (λ_ex , 808 nm) in the green region (≈530 nm), the designed nanovector is capable of releasing cargos at a low-power 808 nm excitation (0.2 W). Considering the high molar absorptivity, biobenign, and synthetic tunability of DASA, DASA PP can be utilized as an up-and-coming candidate to design and synthesize the next generation of upconversion nanovectors without photodamage.

Living polymerizations of propylene sulfide initiated with potassium xanthates characterized by unprecedentedly high propagation rates

In this paper we describe the original thiol-free approach towards the polymerization of propylene sulfide (PS) under various conditions (bulk, solution, and emulsion) initiated with potassium xanthates.

NIR-Light-Activated Ratiometric Fluorescent Hybrid Micelles for High Spatiotemporally Controlled Biological Imaging and Chemotherapy

Intelligent-responsive imaging-therapy strategy has shown great significance for biomedicine. However, it is still a challenge to construct spatiotemporally controlled imaging-therapy systems triggered by near infrared (NIR) light. In this work, NIR-light-activated ratiometric fluorescent hybrid micelles (RFHM) are prepared via the co-assembly of upconversion nanoparticles (UCNPs), doxorubicin (DOX), and UV-light-responsive amphiphilic block copolymer for the spatiotemporally controlled imaging and chemotherapy. Upon NIR light irradiation, UCNPs can convert NIR light to UV light. The emitted UV light induces the photoreaction of copolymer to further trigger ratiometric fluorescence imaging and degradation of hybrid micelles, resulting in rapid DOX release from hybrid micelles for antitumor therapy. The animal experiments reveal that NIR light can not only remotely regulate the ratiometric fluorescence imaging of RFHM in tumor tissue, but also trigger DOX release from RFHM to inhibit tumor growth. Therefore, this study provides a new strategy to achieve high spatial-temporal-controlled biological imaging and chemotherapy.