Semiconducting Polymer Nanoparticles for Photoactivatable Cancer Immunotherapy and Imaging of Immunoactivation

Self-amplified activatable nanophotosensitizers for HIF-1α inhibition-enhanced photodynamic therapy

Activatable photodynamic therapy (PDT) has shown great potential in cancer therapy owing to its high tumor specificity and minimized side effect. However, the relatively low level of biomarkers within tumor tissue rescricts the photosensitizer to get thoroughly activated. In this study, we design a self-amplified activatable nanophotosensitizer (CPPa NP) for enhanced PDT. CPPa NP is prepared by encapsulating a hypoxia-inducible factor 1α (HIF-1α) inhibitor CI-994 with an amphiphilic hydrogen peroxide (H2O2) responsive copolymer PPa-CA-PEG. Upon the addition of H2O2, the thioketal linker within CPPa NP is cleaved, resulting in the simultaneous release of thiol-modified pyropheophorbide a (PPa-SH), cinnamic aldehyde (CA), and CI-994. PPa-SH can be encapsulated by albumin to turn on its photodynamic efficiency, while CI-994 may inhibit the expression of HIF-1α to improve the PDT efficacy. CA is able to deplete glutathione (GSH) and upregulate reactive oxygen species (ROS) within tumor cells, accelerating the dissociation of nanoparticles and disrupting the redox balance of tumor cells. In vitro and in vivo studies showed that CPPa NP can successfully elevate the ROS level within 4T1 cells and has a better anticancer efficacy than PPa NP without CI-994 under laser irradiation. This study thus provides an effective approach to develop self-amplified activatable nanoparticles for enhanced PDT.

Size Modulation of Conjugated Polymer Nanoparticles for Improved NIR-II Fluorescence Imaging and Photothermal Therapy

Near-infrared-II fluorescence imaging (NIR-II FI) has become a powerful imaging technique for disease diagnosis owing to its superiorities, including high sensitivity, high spatial resolution, deep imaging depth, and low background interference. Despite the widespread application of conjugated polymer nanoparticles (CPNs) for NIR-II FI, most of the developed CPNs have quite low NIR-II fluorescence quantum yields based on the energy gap law, which makes high-sensitivity and high-resolution imaging toward deep lesions still a huge challenge. This work proposes a nanoengineering strategy to modulate the size of CPNs aimed at optimizing their NIR-II fluorescence performance for improved NIR-II phototheranostics. By adjusting the initial concentration of the synthesized conjugated polymer, a series of CPNs with different particle sizes are successfully prepared via a nanoprecipitation approach. Results show that the NIR-II fluorescence brightness of CPNs gradually amplifies with decreasing particle size, and the optimal CPNs, NP0.2, demonstrate up to a 2.05-fold fluorescence enhancement compared with the counterpart nanoparticles. With the merits of reliable biocompatibility, high photostability, and efficient light-heat conversion, the optimal NP0.2 has been successfully employed for NIR-II FI-guided photothermal therapy both in vitro and in vivo. Our work highlights an effective strategy of nanoengineering to improve the NIR-II performance of CPNs, advancing the development of NIR-II FI in life sciences.

Nano-phototherapy: Favorable prospects for cancer treatment

Nanotechnology-based phototherapies have drawn interest in the fight against cancer because of its noninvasiveness, high flexibility, and precision in terms of cancer targeting and drug delivery based on its surface properties and size. Phototherapy has made remarkable development in recent decades. Approaches to phototherapy, which utilize nanomaterials or nanotechnology have emerged to contribute to advances around nanotechnologies in medicine, particularly for cancers. A brief overviews of the development of photodynamic therapy as well as its mechanism in cancer treatment is provided. We emphasize the design of novel nanoparticles utilized in photodynamic therapy while summarizing the representative progress during the recent years. Finally, to forecast important future research in this area, we examine the viability and promise of photodynamic therapy systems based on nanoparticles in clinical anticancer treatment applications and briefly make mention of the elimination of all reactive metabolites pertaining to nano formulations inside living organisms providing insight into clinical mechanistic processes. Future developments and therapeutic prospects for photodynamic treatments are anticipated. Our viewpoints might encourage scientists to create more potent phototherapy-based cancer therapeutic modalities. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Leveraging Semiconducting Polymer Nanoparticles for Combination Cancer Immunotherapy

Cancer immunotherapy has become a promising method for cancer treatment, bringing hope to advanced cancer patients. However, immune-related adverse events caused by immunotherapy also bring heavy burden to patients. Semiconducting polymer nanoparticles (SPNs) as an emerging nanomaterial with high biocompatibility, can eliminate tumors and induce tumor immunogenic cell death through different therapeutic modalities, including photothermal therapy, photodynamic therapy, and sonodynamic therapy. In addition, SPNs can work as a functional nanocarrier to synergize with a variety of immunomodulators to amplify anti-tumor immune responses. In this review, SPNs-based combination cancer immunotherapy is comprehensively summarized according to the SPNs' therapeutic modalities and the type of loaded immunomodulators. The in-depth understanding of existing SPNs-based therapeutic modalities will hopefully inspire the design of more novel nanomaterials with potent anti-tumor immune effects, and ultimately promote their clinical translation.

Stimuli-responsive (nano)architectures for phytochemical delivery in cancer therapy

The use of phytochemicals for purpose of cancer therapy has been accelerated due to resistance of tumor cells to conventional chemotherapy drugs and therefore, monotherapy does not cause significant improvement in the prognosis and survival of patients. Therefore, administration of natural products alone or in combination with chemotherapy drugs due to various mechanisms of action has been suggested. However, cancer therapy using phytochemicals requires more attention because of poor bioavailability of compounds and lack of specific accumulation at tumor site. Hence, nanocarriers for specific delivery of phytochemicals in tumor therapy has been suggested. The pharmacokinetic profile of natural products and their therapeutic indices can be improved. The nanocarriers can improve potential of natural products in crossing over BBB and also, promote internalization in cancer cells through endocytosis. Moreover, (nano)platforms can deliver both natural and synthetic anti-cancer drugs in combination cancer therapy. The surface functionalization of nanostructures with ligands improves ability in internalization in tumor cells and improving cytotoxicity of natural compounds. Interestingly, stimuli-responsive nanostructures that respond to endogenous and exogenous stimuli have been employed for delivery of natural compounds in cancer therapy. The decrease in pH in tumor microenvironment causes degradation of bonds in nanostructures to release cargo and when changes in GSH levels occur, it also mediates drug release from nanocarriers. Moreover, enzymes in the tumor microenvironment such as MMP-2 can mediate drug release from nanocarriers and more progresses in targeted drug delivery obtained by application of nanoparticles that are responsive to exogenous stimulus including light.

Immuno-photodynamic Therapy (IPDT): Organic Photosensitizers and Their Application in Cancer Ablation

Photosensitizer-based photodynamic therapy (PDT) has been considered as a promising modality for fighting diverse types of cancers. PDT directly inhibits local tumors by a minimally invasive strategy, but it seems to be incapable of achieving complete eradication and fails to prevent metastasis and recurrence. Recently, increasing events proved that PDT was associated with immunotherapy by triggering immunogenic cell death (ICD). Upon a specific wavelength of light irradiation, the photosensitizers will turn the surrounding oxygen molecules into cytotoxic reactive oxygen species (ROS) for killing the cancer cells. Simultaneously, the dying tumor cells release tumor-associated antigens, which could improve immunogenicity to activate immune cells. However, the progressively enhanced immunity is typically limited by the intrinsic immunosuppressive tumor microenvironment (TME). To overcome this obstacle, immuno-photodynamic therapy (IPDT) has come to be one of the most beneficial strategies, which takes advantage of PDT to stimulate the immune response and unite immunotherapy for inducing immune-OFF tumors to immune-ON ones, to achieve systemic immune response and prevent cancer recurrence. In this Perspective, we provide a review of recent advances in organic photosensitizer-based IPDT. The general process of immune responses triggered by photosensitizers (PSs) and how to enhance the antitumor immune pathway by modifying the chemical structure or conjugating with a targeting component was discussed. In addition, future perspectives and challenges associated with IPDT strategies are also discussed. We hope this Perspective could inspire more innovative ideas and provide executable strategies for future developments in the war against cancer.

A novel donor-acceptor structured diketopyrrolopyrrole-based conjugated polymer synthesized by direct arylation polycondensation (DArP) for highly efficient antimicrobial photothermal therapy

A novel donor (D)-acceptor (A) structured conjugated polymer (PDPP-TP), which contains two alternating D-A pairs, namely thiophene (T)-diketopyrrolopyrrole (DPP) and thiophenen (T)-thieno[3,4-b]pyrazine (TP) along the main chain of the polymer, was synthesized by direct arylation polycondensation (DArP) for a highly efficient photothermal antibacterial treatment. The hydrophilic PDPP-TP-based nanoparticles (PTNPs) with a hydration diameter of about 120 nm were obtained by self-assembly using DSPE-mPEG₂₀₀₀ as the polymer matrix. PTNPs show strong near-infrared (NIR) absorbance with a λ_max at 910 nm (ε = 2.25 × 10⁴ L mol^-1 cm^-1) and NIR light-triggered photoactivity with a high photothermal conversion efficiency (PTCE) of 52.8% under 880 nm laser irradiation. Keeping the merits of excellent biocompatibility and photostability, PTNPs exhibited remarkable bacterial inhibition efficiency of almost 100% against Gram-negative E. coli and Gram-positive S. aureus with the help of an 880 nm laser (0.7 W cm^-2, 6 min), demonstrating its great potential as photothermal materials with a broad spectrum of activity for the effective treatment of microbial infections.

Recent advances in mixing-induced nanoprecipitation: from creating complex nanostructures to emerging applications beyond biomedicine

Mixing-induced nanoprecipitation (MINP) is an efficient, controllable, scalable, versatile, and cost-effective technique for the preparation of nanoparticles. In addition to the formulation of drugs, MINP has attracted tremendous interest in other fields. In this review, we highlight recent advances in the preparation of nanoparticles with complex nanostructures via MINP and their emerging applications beyond biomedicine. First, the mechanisms of nanoprecipitation and four mixing approaches for MINP are briefly discussed. Next, three strategies for the preparation of nanoparticles with complex nanostructures including sequential nanoprecipitation, controlling phase separation, and incorporating inorganic nanoparticles, are summarized. Then, emerging applications including the engineering of catalytic nanomaterials, environmentally friendly photovoltaic inks, colloidal surfactants for the preparation of Pickering emulsions, and green templates for the synthesis of nanomaterials, are reviewed. Furthermore, we discuss the structure-function relationships to gain more insight into design principles for the development of functional nanoparticles via MINP. Finally, the remaining issues and future applications are discussed. This review will stimulate the development of nanoparticles with complex nanostructures and their broader applications beyond biomedicine.

Nanoparticles-based phototherapy systems for cancer treatment: Current status and clinical potential

Remarkable progress in phototherapy has been made in recent decades, due to its non-invasiveness and instant therapeutic efficacy. In addition, with the rapid development of nanoscience and nanotechnology, phototherapy systems based on nanoparticles or nanocomposites also evolved as an emerging hotspot in nanomedicine research, especially in cancer. In this review, first we briefly introduce the history of phototherapy, and the mechanisms of phototherapy in cancer treatment. Then, we summarize the representative development over the past three to five years in nanoparticle-based phototherapy and highlight the design of the innovative nanoparticles thereof. Finally, we discuss the feasibility and the potential of the nanoparticle-based phototherapy systems in clinical anticancer therapeutic applications, aiming to predict future research directions in this field. Our review is a tutorial work, aiming at providing useful insights to researchers in the field of nanotechnology, nanoscience and cancer.

Oncolytic virus: A catalyst for the treatment of gastric cancer

Gastric cancer (GC) is a leading contributor to global cancer incidence and mortality. According to the GLOBOCAN 2020 estimates of incidence and mortality for 36 cancers in 185 countries produced by the International Agency for Research on Cancer (IARC), GC ranks fifth and fourth, respectively, and seriously threatens the survival and health of people all over the world. Therefore, how to effectively treat GC has become an urgent problem for medical personnel and scientific workers at this stage. Due to the unobvious early symptoms and the influence of some adverse factors such as tumor heterogeneity and low immunogenicity, patients with advanced gastric cancer (AGC) cannot benefit significantly from treatments such as radical surgical resection, radiotherapy, chemotherapy, and targeted therapy. As an emerging cancer immunotherapy, oncolytic virotherapies (OVTs) can not only selectively lyse cancer cells, but also induce a systemic antitumor immune response. This unique ability to turn unresponsive 'cold' tumors into responsive 'hot' tumors gives them great potential in GC therapy. This review integrates most experimental studies and clinical trials of various oncolytic viruses (OVs) in the diagnosis and treatment of GC. It also exhaustively introduces the concrete mechanism of invading GC cells and the viral genome composition of adenovirus and herpes simplex virus type 1 (HSV-1). At the end of the article, some prospects are put forward to determine the developmental directions of OVTs for GC in the future.

Self-Splittable Transcytosis Nanoraspberry for NIR-II Photo-Immunometabolic Cancer Therapy in Deep Tumor Tissue

Cancer photo-immunotherapy (CPIT) as an ideal strategy can rapidly release hostile signals by appropriate dosage of focal laser irradiation to unmask primary tumor immunogenicity and can activate adaptive immunity to control distant metastases. However, many factors, including disordered immunometabolism, poor penetration of photothermal agents and immuno-regulators, inadequate laser penetration into the deep tumor region, restrict the therapeutic outcomes of CPIT. Here, a second near-infrared window (NIR-II) photo-immunometabolic cancer therapy (PICT) by a programmed raspberry-structured nanoadjuvant (PRN^MT ) is presented that can potentiates efficient immunogenic cell death (ICD) in deep tumor tissue and alleviates immunometabolic disorder. The PRN^MT is architected through self-assembly of indoleamine 2,3-dioxygenase 1 (IDO-1) inhibitor modified small-sized CuS nanoparticles (CuS₅ ) and tumor microenvironment (TME) responsive cationized polymeric matrix. The TME can trigger the splitting and surface cationization of PRN^MT into small cationized CuS₅ that feature high transcytosis potential and TME immunometabolic regulation. Upon NIR-II irradiation, CuS₅ induce homogeneous ICD and release immunometabolic regulator in deep tumor tissues, which ameliorates IDO-1 mediated immunometabolic disorder and further suppresses regulatory T cells infiltration. PRN^MT mediated PICT effectively delays the primary murine mammary carcinoma 4T1 tumor growth and inhibits the lethal pulmonary metastasis in combination with programmed cell death protein 1 (PD1) blockade.

Co-delivery of proanthocyanidin and mitoxantrone induce synergistic immunogenic cell death to potentiate cancer immunotherapy

Immunological checkpoint inhibitors provide a revolutionary method for cancer treatment. However, due to low tumor mutations and insufficient infiltration of immune cells in the tumor microenvironment, 85% of colorectal cancer...