Drug delivery micelles with efficient near-infrared photosensitizer for combined image-guided photodynamic therapy and chemotherapy of drug-resistant cancer

A carrier-free nanovaccine combined with cancer immunotherapy overcomes gemcitabine resistance

Drug resistance is a significant challenge in cancer chemotherapy and is a primary factor contributing to poor recovery for cancer patients. Although drug-loaded nanoparticles have shown promise in overcoming chemotherapy resistance, they often carry a combination of drugs and require advanced design and manufacturing processes. Furthermore, they seldom approach chemotherapy-resistant tumors from an immunotherapy perspective. In this study, we developed a therapeutic nanovaccine composed solely of chemotherapy-induced resistant tumor antigens (CIRTAs) and the immune adjuvant Toll-like receptor (TLR) 7/8 agonist R848 (CIRTAs@R848). This nanovaccine does not require additional carriers and has a simple production process. It efficiently delivers antigens and immune stimulants to dendritic cells (DCs) simultaneously, promoting DCs maturation. CIRTAs@R848 demonstrated significant tumor suppression, particularly when used in combination with the immune checkpoint blockade (ICB) anti-PD-1 (αPD-1). The combined therapy increased the infiltration of T cells into the tumor while decreasing the proportion of regulatory T cells (Tregs) and modulating the tumor microenvironment, resulting in long-term immune memory. Overall, this study introduces an innovative strategy for treating chemotherapy-resistant tumors from a novel perspective, with potential applications in personalized immunotherapy and precision medicine.

Recent Applications of Amphiphilic Copolymers in Drug Release Systems for Skin Treatment

Amphiphilic copolymers (ACs) are versatile systems with self-assembling and aggregating properties, enabling the formation of nanomaterials (NMs) such as micelles, vesicles, nanocapsules, and nanogels. These materials have been extensively explored for the delivery of various drugs and active compounds, enhancing the solubility and permeation of poorly water-soluble drugs into skin tissue. This improvement facilitates the treatment of skin diseases, including chronic conditions like cancer, as well as infections caused by bacteria, fungi, and viruses. This review summarizes recent applications of ACs in skin treatment, with a particular focus on their use in anti-cancer drug therapy. It covers the synthesis, classification, and characterization of ACs using various experimental techniques. Additionally, it discusses recent research on different drug delivery pathways using ACs, including encapsulation efficiency, release behavior, characteristics, applications, and responses to various chemical and physical stimuli (both in vivo and in vitro). Furthermore, this review provides a comprehensive analysis of the effects of ACs NMs on several skin diseases, highlighting their potential as alternative treatments.

Smart delivery vehicles for cancer: categories, unique roles and therapeutic strategies

Chemotherapy and surgery remain the primary treatment modalities for cancers; however, these techniques have drawbacks, such as cancer recurrence and toxic side effects, necessitating more efficient cancer treatment strategies. Recent advancements in research and medical technology have provided novel insights and expanded our understanding of cancer development; consequently, scholars have investigated several delivery vehicles for cancer therapy to improve the efficiency of cancer treatment and patient outcomes. Herein, we summarize several types of smart therapeutic carriers and elaborate on the mechanism underlying drug delivery. We reveal the advantages of smart therapeutic carriers for cancer treatment, focus on their effectiveness in cancer immunotherapy, and discuss the application of smart cancer therapy vehicles in combination with other emerging therapeutic strategies for cancer treatment. Finally, we summarize the bottlenecks encountered in the development of smart cancer therapeutic vehicles and suggest directions for future research. This review will promote progress in smart cancer therapy and facilitate related research.

Recent advances in photodynamic therapy combined with chemotherapy for cervical cancer: a systematic review

INTRODUCTION

Despite the evidence that photodynamic therapy (PDT) associated with chemotherapy presents great potential to overcome the limitations of monotherapy, little is known about the current status of this combination against cervical cancer. This systematic review aimed to address the currently available advances in combining PDT and chemotherapy in different research models and clinical trials of cervical cancer.

METHODS

We conducted a systematic review based on PRISMA Statement and Open Science Framework review protocol using PubMed, Web of Science, Embase, Scopus, LILACS, and Cochrane databases. We selected original articles focusing on 'Uterine Cervical Neoplasms' and 'Photochemotherapy and Chemotherapy' published in the last 10 years. The risk of bias in the studies was assessed using the CONSORT and SYRCLE tools.

RESULTS

Twenty-three original articles were included, focusing on HeLa cells, derived from endocervical adenocarcinoma and on combinations of several chemotherapeutics. Most of the combinations used modern drug delivery systems for improved simultaneous delivery and presented promising results with increased cytotoxicity compared to monotherapy.

CONCLUSION

Despite the scarcity of animal studies and the absence of clinical studies, the combination of chemotherapy with PDT presents a potential option for cervical cancer therapy requiring additional studies.

OSF REGISTRATION

https://doi.org/10.17605/OSF.IO/WPHN5 [Figure: see text].

FAP Targeting of Photosensitizer-Loaded Polymersomes for Increased Light-Activated Cell Killing

As current chemo- and photodynamic cancer therapies are associated with severe side effects due to a lack of specificity and to systemic toxicity, innovative solutions in terms of targeting and controlled functionality are in high demand. Here, we present the development of a polymersome nanocarrier equipped with targeting molecules and loaded with photosensitizers for efficient uptake and light-activated cell killing. Polymersomes were self-assembled in the presence of photosensitizers from a mixture of nonfunctionalized and functionalized PDMS-b-PMOXA diblock copolymers, the latter designed for coupling with targeting ligands. By encapsulation inside the polymersomes, the photosensitizer Rose Bengal was protected, and its uptake into cells was mediated by the nanocarrier. Inhibitor of fibroblast activation protein α (FAPi), a ligand for FAP, was attached to the polymersomes' surface and improved their uptake in MCF-7 breast cancer cells expressing relatively high levels of FAP on their surface. Once internalized by MCF-7, irradiation of Rose Bengal-loaded FAPi-polymersomes generated reactive oxygen species at levels high enough to induce cell death. By combining photosensitizer encapsulation and specific targeting, polymersomes represent ideal candidates as therapeutic nanocarriers in cancer treatment.

Advancing Cancer Treatment: Enhanced Combination Therapy through Functionalized Porous Nanoparticles

Cancer remains a major global health challenge, necessitating the development of innovative treatment strategies. This review focuses on the functionalization of porous nanoparticles for combination therapy, a promising approach to enhance cancer treatment efficacy while mitigating the limitations associated with conventional methods. Combination therapy, integrating multiple treatment modalities such as chemotherapy, phototherapy, immunotherapy, and others, has emerged as an effective strategy to address the shortcomings of individual treatments. The unique properties of mesoporous silica nanoparticles (MSN) and other porous materials, like nanoparticles coated with mesoporous silica (NP@MS), metal-organic frameworks (MOF), mesoporous platinum nanoparticles (mesoPt), and carbon dots (CDs), are being explored for drug solubility, bioavailability, targeted delivery, and controlled drug release. Recent advancements in the functionalization of mesoporous nanoparticles with ligands, biomaterials, and polymers are reviewed here, highlighting their role in enhancing the efficacy of combination therapy. Various research has demonstrated the effectiveness of these nanoparticles in co-delivering drugs and photosensitizers, achieving targeted delivery, and responding to multiple stimuli for controlled drug release. This review introduces the synthesis and functionalization methods of these porous nanoparticles, along with their applications in combination therapy.

NIR light-facilitated bone tissue engineering

In the last decades, near-infrared (NIR) light has attracted considerable attention due to its unique properties and numerous potential applications in bioimaging and disease treatment. Bone tissue engineering for bone regeneration with the help of biomaterials is currently an effective means of treating bone defects. As a controlled light source with deeper tissue penetration, NIR light can provide real-time feedback of key information on bone regeneration in vivo utilizing fluorescence imaging and be used for bone disease treatment. This review provides a comprehensive overview of NIR light-facilitated bone tissue engineering, from the introduction of NIR probes as well as NIR light-responsive materials, and the visualization of bone regeneration to the treatment of bone-related diseases. Furthermore, the existing challenges and future development directions of NIR light-based bone tissue engineering are also discussed. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

The diverse effects of cisplatin on tumor microenvironment: Insights and challenges for the delivery of cisplatin by nanoparticles

Cisplatin is a well-known platinum-based chemotherapy medication that is widely utilized for some malignancies. Despite the direct cytotoxic consequences of cisplatin on tumor cells, studies in the recent decade have revealed that cisplatin can also affect different cells and their secretions in the tumor microenvironment (TME). Cisplatin has complex impacts on the TME, which may contribute to its anti-tumor activity or drug resistance mechanisms. These regulatory effects of cisplatin play a paramount function in tumor growth, invasion, and metastasis. This paper aims to review the diverse impacts of cisplatin and nanoparticles loaded with cisplatin on cancer cells and also non-cancerous cells in TME. The impacts of cisplatin on immune cells, tumor stroma, cancer cells, and also hypoxia will be discussed in the current review. Furthermore, we emphasize the challenges and prospects of using cisplatin in combination with other adjuvants and therapeutic modalities that target TME. We also discuss the potential synergistic effects of cisplatin with immune checkpoint inhibitors (ICIs) and other agents with anticancer potentials such as polyphenols and photosensitizers. Furthermore, the potential of nanoparticles for targeting TME and better delivery of cisplatin into tumors will be discussed.

Rational design of β-carboline as an efficient type I/II photosensitizer to enable hypoxia-tolerant chemo-photodynamic therapy

Photodynamic therapy (PDT) is a clinically approved treatment for cancer due to its high spatiotemporal selectivity and non-invasive modality. However, its therapeutic outcomes are always limited to the severe hypoxia environment of the solid tumor. Herein, two novel photosensitizers HY and HYM based on naturally antitumor alkaloids β-carboline were designed and synthesized. Through a series of experiments, we found HY and HYM can produce type II ROS (singlet oxygen) after light irradiation. HYM had higher singlet oxygen quantum yield and molar extinction coefficient than HY, as well as type I PDT behavior, which further let us find that HYM could exhibit robust phototoxicity activities in both normoxia and hypoxia. Meanwhile, HYM showed tumor-selective cytotoxicity with minimal toxicity toward normal cells. Notably, thanks to HYM's hypoxia-tolerant type I/II PDT and tumor selective chemotherapy, HYM showed synergistic inhibitory effect on tumor growth (inhibition rate > 91%). Our research provides a promising photosensitizer for hypoxia-tolerant chemo-photodynamic therapy, and may also give a novel molecular skeleton for photosensitizer design.

Conjugated Polymeric Materials in Biological Imaging and Cancer Therapy

Conjugated polymers (CPs) have attracted much attention in the fields of chemistry, medicine, life science, and material science. Researchers have carried out a series of innovative researches and have made significant research progress regarding the unique photochemical and photophysical properties of CPs, expanding the application range of polymers. CPs are polymers formed by the conjugation of multiple repeating light-emitting units. Through precise control of their structure, functional molecules with different properties can be obtained. Fluorescence probes with different absorption and emission wavelengths can be obtained by changing the main chain structure. By modifying the side chain structure with water-soluble groups or selective recognition molecules, electrostatic interaction or specific binding with specific targets can be achieved; subsequently, the purpose of selective recognition can be achieved. This article reviews the research work of CPs in cell imaging, tumor diagnosis, and treatment in recent years, summarizes the latest progress in the application of CPs in imaging, tumor diagnosis, and treatment, and discusses the future development direction of CPs in cell imaging, tumor diagnosis, and treatment.

Orange/Red Benzo[1,2-b:4,5-b']dithiophene 1,1,5,5-Tetraoxide-Based Emitters for Luminescent Solar Concentrators: Effect of Structures on Fluorescence Properties and Device Performances

Luminescent solar concentrators (LSCs) are a class of optical devices able to harvest, downshift, and concentrate sunlight, thanks to the presence of emitting materials embedded in a polymer matrix. Use of LSCs in combination with silicon-based photovoltaic (PV) devices has been proposed as a viable strategy to enhance their ability to harvest diffuse light and facilitate their integration in the built environment. LSC performances can be improved by employing organic fluorophores with strong light absorption in the center of the solar spectrum and intense, red-shifted emission. In this work, we present the design, synthesis, characterization, and application in LSCs of a series of orange/red organic emitters featuring a benzo[1,2-b:4,5-b']dithiophene 1,1,5,5-tetraoxide central core as an acceptor (A) unit. The latter was connected to different donor (D) and acceptor (A') moieties by means of Pd-catalyzed direct arylation reactions, yielding compounds with either symmetric (D-A-D) or non-symmetric (D-A-A') structures. We found that upon light absorption, the compounds attained excited states with a strong intramolecular charge-transfer character, whose evolution was greatly influenced by the nature of the substituents. In general, symmetric structures showed better photophysical properties for the application in LSCs than their non-symmetric counterparts, and using a donor group of moderate strength such as triphenylamine was found preferable. The best LSC built with these compounds presented photonic (external quantum efficiency of 8.4 ± 0.1%) and PV (device efficiency of 0.94 ± 0.06%) performances close to the state-of-the-art, coupled with a sufficient stability in accelerated aging tests.

Overcoming Cancer Multi-drug Resistance (MDR): Reasons, mechanisms, nanotherapeutic solutions, and challenges

Multi-drug resistance (MDR) in cancer cells, either intrinsic or acquired through various mechanisms, significantly hinders the therapeutic efficacy of drugs. Typically, the reduced therapeutic performance of various drugs is predominantly due to the inherent over expression of ATP-binding cassette (ABC) transporter proteins on the cell membrane, resulting in the deprived uptake of drugs, augmenting drug detoxification, and DNA repair. In addition to various physiological abnormalities and extensive blood flow, MDR cancer phenotypes exhibit improved apoptotic threshold and drug efflux efficiency. These severe consequences have substantially directed researchers in the fabrication of various advanced therapeutic strategies, such as co-delivery of drugs along with various generations of MDR inhibitors, augmented dosage regimens and frequency of administration, as well as combinatorial treatment options, among others. In this review, we emphasize different reasons and mechanisms responsible for MDR in cancer, including but not limited to the known drug efflux mechanisms mediated by permeability glycoprotein (P-gp) and other pumps, reduced drug uptake, altered DNA repair, and drug targets, among others. Further, an emphasis on specific cancers that share pathogenesis in executing MDR and effluxed drugs in common is provided. Then, the aspects related to various nanomaterials-based supramolecular programmable designs (organic- and inorganic-based materials), as well as physical approaches (light- and ultrasound-based therapies), are discussed, highlighting the unsolved issues and future advancements. Finally, we summarize the review with interesting perspectives and future trends, exploring further opportunities to overcome MDR.

Apoptosis-Amplified Assembly of Porphyrin Nanofiber Enhances Photodynamic Therapy of Oral Tumor

Oral squamous cell carcinoma (OSCC) is the most common oral cancer, having high recurrence and metastasis features. In addition to surgery, photodynamic therapy (PDT) is considered as another effective approach for OSCC treatment. The water solubility of currently available PDT photosensitizers (PSs) is poor, lowering their singlet oxygen (¹O₂) yield and consequent PDT efficiency. Strategies of PS assembly have been reported to increase ¹O₂ yield, but it is still possible to further enhance PDT efficiency. In this work, we utilized apoptosis to amplify the assembly of porphyrin nanofibers for enhanced PDT of OSCC. A water-soluble porphyrin derivative, Ac-Asp-Glu-Val-Asp-Asp-TPP (Ac-DEVDD-TPP), was designed for this purpose. Upon caspase-3 (Casp3, an activated enzyme during apoptosis) cleavage and laser irradiation, Ac-DEVDD-TPP was converted to D-TPP, which spontaneously self-assembled into porphyrin nanofibers, accompanied by 1.4-fold and 2.1-fold ¹O₂ generations in vitro and in cells, respectively. The as-formed porphyrin nanofiber induced efficient cell apoptosis and pyroptosis. In vivo experiments demonstrated that, compared with the scrambled control compound Ac-DEDVD-TPP, Ac-DEVDD-TPP led to 6.2-fold and 1.3-fold expressions of Casp3 in subcutaneous and orthotopic oral tumor models, respectively, and significantly suppressed the tumors. We envision that our strategy of apoptosis-amplified porphyrin assembly might be applied for OSCC treatment in the clinic in the near future.

Translational albumin nanocarrier caging photosensitizer for efficient cancer photodynamic therapy

It still remains a great challenge to efficiently treat malignant cancers which severely threaten human health. Photodynamic therapy (PDT) as a localized therapeutic modality has improved the therapeutic efficacy via chemical damage through reactive oxygen species (ROS). However, their efficacy is severely hampered by insufficient targeted delivery of photosensitizers owing to the lack of suitable carrier with facile preparation process and the clinical applicability. Herein, we applied clinically approved human serum albumin as the nanoreactor to encapsulate photosensitizers Chlorin e6 (Ce6) for enhancing their tumor accumulation and subsequently potent PDT effect against bladder cancer models. Albumin-loaded Chlorin e6 nanoparticles (CA-NPs) with rational nanoscale size exhibit increased reactive oxygen species production and excellent resistance to photobleaching. Moreover, CA-NPs could be efficiently internalized by tumor cells and locate in the lysosome, while they rapidly translocate to cytosol after irradiation to induce remarkable cytotoxicity (IC₅₀ ∼5.8 μg/ml). Furthermore, CA-NPs accumulate effectively in tumor tissue to afford total eradication of murine bladder tumor after single injection. More importantly, we also evidence the superior PDT effect in fresh human bladder tumor tissues via abundant reactive oxygen species generation and subsequent cell apoptosis. These findings demonstrate that human serum albumin acts as a universal tool to load small organic photoactivatable molecule with remarkable effectiveness and readiness for clinical translation.

A Self-Reinforcing Nanoplatform for Highly Effective Synergistic Targeted Combinatary Calcium-Overload and Photodynamic Therapy of Cancer

While calcium-overload-mediated therapy (COMT) is a promising but largely untapped therapeutic strategy, combinatory therapy greatly boosts treatment outcomes with integrated merits of different therapies. Herein, a BPQD@CaO₂ -PEG-GPC3Ab nanoplatform is formulated by integrating calcium peroxide (CaO₂ ) and black phosphorus quantum dot (BPQD, photosensitizer) with active-targeting glypican-3 antibody (GPC3Ab), for combinatory photodynamic therapy (PDT) and COMT in response to acidic pH and near-infrared (NIR) light, wherein CaO₂ serves as the reservoir of calcium ions (Ca²⁺ ) and hydrogen peroxide (H₂ O₂ ). Navigated by GPC3Ab to tumor cells at acidic pH, the nanoparticle disassembles to CaO₂ and BPQD; CaO₂ produces COMT Ca²⁺ and H₂ O₂ , while H₂ O₂ makes oxygen (O₂ ) to promote PDT; under NIR irradiation BPQD facilitates not only the conversion of O₂ to singlet oxygen (¹ O₂ ) for PDT, but also moderate hyperthermia to accelerate NP dissociation to CaO₂ and BPQD, and conversions of CaO₂ to Ca²⁺ and H₂ O₂ , and H₂ O₂ to O₂ , to enhance both COMT and PDT. After supplementary ionomycin treatment to induce intracellular Ca²⁺ bursts, the multimodal therapeutics strikingly induce hepatocellular carcinoma apoptosis, likely through the activation of the calpains and caspases 12, 9, and 3, up-regulation of Bax and down-regulation of Bcl-2 proteins. This nanoplatform enables a mutually-amplifying and self-reinforcing synergistic therapy.

Reversible covalent nanoassemblies for augmented nuclear drug translocation in drug resistance tumor

The drug efflux by P-glycoprotein (P-gp) is the primary contributor of multidrug resistance (MDR), which eventually generates insufficient nuclear drug accumulation and chemotherapy failure. In this paper, reversible covalent nanoassemblies on the basis of catechol-functionalized methoxy poly (ethylene glycol) (mPEG-dop) and phenylboronic acid-modified cholesterol (Chol-PBA) are successfully synthesized for delivery of both doxorubicin (DOX, anti-cancer drug) and tariquidar (TQR, P-glycoprotein inhibitor), which shows efficient nuclear DOX accumulation for overcoming tumor MDR. Through naturally forming phenylboronate linkage in physiological circumstances, Chol-PBA is able to bond with mPEG-dop. The resulting conjugates (PC) could self-assemble into reversible covalent nanoassemblies by dialysis method, and transmission electron microscopy analysis reveals the PC distributes in nano-scaled spherical particles before and after drug encapsulation. Under the assistance of Chol, PC can enter into lysosome of tumor cells via low-density lipoprotein (LDL) receptor-mediated endocytosis. Then the loaded TQR and DOX are released in acidic lysosomal compartments, which inhibit P-gp mediated efflux and elevate nuclear accumulation of DOX, respectively. At last, this drug loaded PC nanoassemblies show significant tumor suppression efficacy in multidrug-resistant tumor models, which suggests great potential for addressing MDR in cancer therapy.

Nanoparticle-Based Combination Therapy for Ovarian Cancer

Ovarian cancer is one of the most common malignant tumors in gynecology with a high incidence. Combination therapy, eg, administration of paclitaxel followed by a platinum anticancer drug is recommended to treat ovarian cancer due to its advantages in, eg, reducing side effects and reversing (multi)drug-resistance compared to single treatment. However, the benefits of combination therapy are often compromised. In chemo and chemo/gene combinations, co-deposition of the combined therapeutics in the tumor cells is required, which is difficult to achieve due to dramatic pharmacokinetic differences between combinational agents in free forms. Moreover, some undesired properties such as the low-water solubility of chemodrugs and the difficulty of cellular internalization of gene therapeutics also hinder the therapeutic potential. Delivery of dual or multiple agents by nanoparticles provides opportunities to tackle these limits. Nanoparticles encapsulate hydrophobic drug(s) to yield aqueous dispersions facilitating its administration and/or to accommodate hydrophilic genes facilitating its access to cells. Moreover, nanoparticle-based therapeutics can not only improve drug properties (eg, in vivo stability) and ensure the same drug disposition behavior with controlled drug ratios but also can minimize drug exposure of the normal tissues and increase drug co-accumulation at targeted tissues via passive and/or active targeting strategies. Herein, this work summarizes nanoparticle-based combination therapies, mainly including anticancer drug-based combinations and chemo/gene combinations, and emphasizes the advantageous outcomes of nanocarriers in the combination treatment of ovarian cancer. In addition, we also review mechanisms of synergetic effects resulting from different combinations.

Recent advances in anti-multidrug resistance for nano-drug delivery system

Chemotherapy for tumors occasionally results in drug resistance, which is the major reason for the treatment failure. Higher drug doses could improve the therapeutic effect, but higher toxicity limits the further treatment. For overcoming drug resistance, functional nano-drug delivery system (NDDS) has been explored to sensitize the anticancer drugs and decrease its side effects, which are applied in combating multidrug resistance (MDR) via a variety of mechanisms including bypassing drug efflux, controlling drug release, and disturbing metabolism. This review starts with a brief report on the major MDR causes. Furthermore, we searched the papers from NDDS and introduced the recent advances in sensitizing the chemotherapeutic drugs against MDR tumors. Finally, we concluded that the NDDS was based on several mechanisms, and we looked forward to the future in this field.

Intelligent poly(l-histidine)-based nanovehicles for controlled drug delivery

Stimuli-responsive drug delivery systems based on polymeric nanovehicles are among the most promising treatment regimens for malignant cancers. Such intelligent systems that release payloads in response to the physiological characteristics of tumor sites have several advantages over conventional drug carriers, offering, in particular, enhanced therapeutic effects and decreased toxicity. The tumor microenvironment (TME) is acidic, suggesting the potential of pH-responsive nanovehicles for enhancing treatment specificity and efficacy. The synthetic polypeptide poly(l-histidine) (PLH) is an appropriate candidate for the preparation of pH-responsive nanovehicles because the pK_a of PLH (approximately 6.0) is close to the pH of the acidic TME. In addition, the pendent imidazole rings of PLH yield pH-dependent hydrophobic-to-hydrophilic phase transitions in the acidic TME, triggering the destabilization of nanovehicles and the subsequent release of encapsulated chemotherapeutic agents. Herein, we highlight the state-of-the-art design and construction of pH-responsive nanovehicles based on PLH and discuss the future challenges and perspectives of this fascinating biomaterial for targeted cancer treatment and "benchtop-to-clinic" translation.

Light-triggered photodynamic nanomedicines for overcoming localized therapeutic efficacy in cancer treatment

Photodynamic nanomedicines have significantly enhanced the therapeutic efficacy of photosensitizers (PSs) by overcoming critical limitations of PSs such as poor water solubility and low tumor accumulation. Furthermore, functional photodynamic nanomedicines have enabled overcoming oxygen depletion during photodynamic therapy (PDT) and tissue light penetration limitation by supplying oxygen or upconverting light in targeted tumor tissues, resulting in providing the potential to overcome biological therapeutic barriers of PDT. Nevertheless, their localized therapeutic effects still remain a huddle for the effective treatment of metastatic- or recurrent tumors. Recently, newly designed photodynamic nanomedicines and their combination chemo- or immune checkpoint inhibitor therapy enable the systemic treatment of various metastatic tumors by eliciting antitumor immune responses via immunogenic cell death (ICD). This review introduces recent advances in photodynamic nanomedicines and their applications, focusing on overcoming current limitations. Finally, the challenges and future perspectives of the clinical translation of photodynamic nanomedicines in cancer PDT are discussed.

Enhanced Permeability and Retention Effect: A key facilitator for solid tumor targeting by nanoparticles

Exploring the enhanced permeability and retention (EPR) effect through therapeutic nanoparticles has been a subject of considerable interest in tumor biology. This passive targeting based phenomenon exploits the leaky blood vasculature and the defective lymphatic drainage system of the heterogeneous tumor microenvironment resulting in enhanced preferential accumulation of the nanoparticles within the tumor tissues. This article reviews the fundamental studies to assess how the EPR effect plays an essential role in passive targeting. Further, it summarizes various therapeutic modalities of nanoformulation including chemo-photodynamic therapy, intravascular drug release, and photothermal immunotherapy to combat cancer using enhanced EPR effect in neoplasia region.

Multifunctional Nanoplatforms as a Novel Effective Approach in Photodynamic Therapy and Chemotherapy, to Overcome Multidrug Resistance in Cancer

It is more than sixty years since the era of modern photodynamic therapy (PDT) for cancer began. Enhanced selectivity for malignant cells with a reduced selectivity for non-malignant cells and good biocompatibility along with the limited occurrence of side effects are considered to be the most significant advantages of PDT in comparison with conventional therapeutic approaches, e.g., chemotherapy. The phenomenon of multidrug resistance, which is associated with drug efflux transporters, was originally identified in relation to the application of chemotherapy. Unfortunately, over the last thirty years, numerous papers have shown that many photosensitizers are the substrates of efflux transporters, significantly restricting the effectiveness of PDT. The concept of a dynamic nanoplatform offers a possible solution to minimize the multidrug resistance effect in cells affected by PDT. Indeed, recent findings have shown that the utilization of nanoparticles could significantly enhance the therapeutic efficacy of PDT. Additionally, multifunctional nanoplatforms could induce the synergistic effect of combined treatment regimens, such as PDT with chemotherapy. Moreover, the surface modifications that are associated with nanoparticle functionalization significantly improve the target potential of PDT or chemo-PDT in multidrug resistant and cancer stem cells.

Synthesis of tetraphenylethene-based D-A conjugated molecules with near-infrared AIE features, and their application in photodynamic therapy

Herein, five aggregation-induced emission (AIE) photosensitizers (PSs) with D-π-A structures are smoothly designed and synthesized through donor and acceptor engineering. The photophysical properties and theoretical calculation results show that the synergistic effect of methoxy substituted tetraphenylethene (MTPE), 3,4-ethylenedioxythiophene can enhance the intramolecular charge transfer effect (ICT), and promote the intersystem crossing (ISC) process of the whole molecule. In these AIE-PSs, the best-performing AIE-PS (MTPE-DT-Py) has bright NIR (740 nm) emission, the highest ¹O₂ generation efficiency (5.9-fold that of Rose Bengal) and efficient mitochondrial targeting ability. Subsequently, PDT anti-cancer and anti-bacterial experiments indicate that MTPE-DT-Py could obviously target mitochondria and kill breast cancer cells (MCF-7), and selectively inactivate S. aureus (G(+)) under white light irradiation. This work mainly proposes a practical design strategy for high effect AIE-PSs and provides more excellent candidates for fluorescence imaging-guided photodynamic therapy.

Photonics of Viburnum opulus L. Extracts in Microemulsions with Oxygen and Gold Nanoparticles

In this paper, the optical properties of viburnum extract flavonoids in the visible region of the spectrum were investigated and their use as a potential photosensitizer of singlet oxygen for photodynamic therapy was evaluated. The presence of long-lived excited states in the extract molecules was established by spectral methods and time-resolved spectroscopy methods and the dependences of the absorption capacity and luminescence intensity of the extract molecules on the concentrations of oxygen and ablative nanoparticles of the gold in the reverse micelles of AOT (sodium dioctyl sulfosuccinate) were established. The plasmonic enhancement of the luminescence of the extract molecules and the processes of their complexation with oxygen were also established. Furthermore, the rate constants of the processes of conversion of exciting energy in complexes were determined.

Recent Progress of Novel Nanotechnology Challenging the Multidrug Resistance of Cancer

Multidrug resistance (MDR) of tumors is one of the clinical direct reasons for chemotherapy failure. MDR directly leads to tumor recurrence and metastasis, with extremely grievous mortality. Engineering a novel nano-delivery system for the treatment of MDR tumors has become an important part of nanotechnology. Herein, this review will take those different mechanisms of MDR as the classification standards and systematically summarize the advances in nanotechnology targeting different mechanisms of MDR in recent years. However, it still needs to be seriously considered that there are still some thorny problems in the application of the nano-delivery system against MDR tumors, including the excessive utilization of carrier materials, low drug-loading capacity, relatively narrow targeting mechanism, and so on. It is hoped that through the continuous development of nanotechnology, nano-delivery systems with more universal uses and a simpler preparation process can be obtained, for achieving the goal of defeating cancer MDR and accelerating clinical transformation.

Size-Transformable Bicomponent Peptide Nanoparticles for Deep Tumor Penetration and Photo-Chemo Combined Antitumor Therapy

The suitable size of multifunctional nanomedicines strongly influences their physicochemical properties and actions in biological systems, for example, prolonged blood circulation time, efficient tumor accumulation, and deep tumor penetration. However, it is still a great challenge to construct size-transformable nanoparticles (NPs) for both efficient accumulation and penetration throughout tumor tissue. Herein, a size-transformed multifunctional NP is developed through a simple bicomponent assembling strategy for enhanced tumor penetration and efficient photo-chemo combined antitumor therapy, due to the acidic tumor microenvironment and near infrared-laser irradiation induced size-shrink. This multifunctional bicomponent NP (PP NP) driven by electrostatic interaction is composed of negatively charged peptide amphiphile (PA1) and positively charged peptide prodrug (PA2). PP NPs (≈170 nm) have been proven to improve blood circulation time and stability in biological environments. Interestingly, PP NPs can reassemble small NPs (<30 nm) by responding to acidic tumor microenvironment and near-infrared laser irradiation, which facilitates deep tumor penetration and improves cellular internalization. By integrating fluorescence imaging, tumor targeting, deep tumor penetration, and combined photo-chemotherapy, PP NPs exhibit excellent in vivo antitumor efficacy. This study might provide an insight for developing a bicomponent assembling system with efficient tumor penetration and multimode for antitumor therapy.

Synergic Antitumor Effect of Photodynamic Therapy and Chemotherapy Mediated by Nano Drug Delivery Systems

This review provides a summary of recent progress in the development of different nano-platforms for the efficient synergistic effect between photodynamic therapy and chemotherapy. In particular, this review focuses on various methods in which photosensitizers and chemotherapeutic agents are co-delivered to the targeted tumor site. In many cases, the photosensitizers act as drug carriers, but this review, also covers different types of appropriate nanocarriers that aid in the delivery of photosensitizers to the tumor site. These nanocarriers include transition metal, silica and graphene-based materials, liposomes, dendrimers, polymers, metal–organic frameworks, nano emulsions, and biologically derived nanocarriers. Many studies have demonstrated various benefits from using these nanocarriers including enhanced water solubility, stability, longer circulation times, and higher accumulation of therapeutic agents/photosensitizers at tumor sites. This review also describes novel approaches from different research groups that utilize various targeting strategies to increase treatment efficacy through simultaneous photodynamic therapy and chemotherapy.

Novel ROS-responsive marine biomaterial fucoidan nanocarriers with AIE effect and chemodynamic therapy

Chemodynamic therapy (CDT) has been widely used in the treatment of many kinds of tumors, which can effectively induce tumor cell apoptosis by using produced reactive oxygen species (ROS). In this paper, ROS-sensitive multifunctional marine biomaterial natural polysaccharide nanoparticles were designed. Aggregation-induced emission (AIE) molecules tetraphenylethylene (TPE) labeled and caffeic acid (CA) modified fucoidan (FUC) amphiphilic carrier material (CA-FUC-TK-TPE, CFTT) was fabricated, in which the thioketal bond(TK) was used as the linkage arm between TPE and fucoidan chain, giving the CFTT material ROS sensitivity. In addition, amphiphilic carrier material (FUC-TK-VE, FTVE) composed of thioketal-linked vitamin E and fucoidan was synthesized. The mixed carrier material CFTT and FTVE self-assembled in water to form nanoparticles (CFTT - FTVE@PTX-Fe³⁺) loaded with PTX and Fe³⁺. The CDT effect was combined with the chemotherapeutic drug PTX to achieve tumor inhibition. In vitro cell studies have proved that CT/PTX nanoparticles have excellent cell permeability and tumor cytotoxicity. In vivo antitumor experiments confirmed effective antitumor activity and reduced side effects.

Covalent RGD-graphene-phthalocyanine nanocomposite for fluorescence imaging-guided dual active/passive tumor-targeted combinatorial phototherapy

Poor tumor selectivity, low stability and quenched fluorescence are the main challenges to be overcome for nanomedicine, and are mainly caused by the dissociation of the nanostructure and aggregation of chromophores in the biological environment. Herein, covalently connected nanoparticles RGD-graphene-phthalocyanine (RGD-GO-SiPc) were constructed based on RGD peptide, silicon phthalocyanine (SiPc) and graphene oxide (GO) via a conjugation reaction for fluorescence imaging-guided cancer-targeted combinatorial phototherapy. The prepared RGD-GO-SiPc exhibited supreme biological stability, high-contrast fluorescence imaging, significantly enhanced NIR absorption, high photothermal conversion efficiency (25.6%), greatly improved cancer-targeting capability, and synergistic photodynamic (PDT) and photothermal therapy (PTT) efficacy along with low toxicity. Both in vitro and in vivo biological studies showed that RGD-GO-SiPc is a kind of promising multifunctional nanomedicine for fluorescence imaging-guided combined photothermal and photodynamic therapy with dual active/passive tumor-targeting properties.

H2O2-Responsive amphiphilic polymer with aggregation-induced emission (AIE) for DOX delivery and tumor therapy

Stimuli-responsive drug delivery systems (DDSs) based on amphiphilic polymers have attracted much attention. In this study, we reported an innovative H₂O₂-responsive amphiphilic polymer (TBP), bearing a H₂O₂-sensitive phenylboronic ester, AIE fluorophore tetraphenylethene (TPE) hydrophobic, and polyethylene glycol hydrophilic (PEG) moieties. TBP could self-assemble into micelles with an encapsulation efficiency as high as 74.9% for doxorubicin (DOX) in aqueous solution. In the presence of H₂O₂, TBP micelles was decomposed by oxidation, hydrolysis and rearrangement, leading to almost 80% DOX release from TBP@DOX micelles. TBP and the corresponding degradation products were biocompatible, while TBP@DOX micelles only displayed obvious toxicity toward cancer cells. Drug delivery process was clearly monitored by confocal laser scanning microscopic (CLSM) and flow cytometry (FCM) analysis. Moreover, in vivo anticancer study showed that TBP@DOX micelles were accumulated in tumor region of nude mice and effectively inhibited tumor growth. The results suggested that the reported H₂O₂-responsive amphiphilic polymer displayed great potential in drug delivery and tumor therapy.

PEG-Polymer Encapsulated Aggregation-Induced Emission Nanoparticles for Tumor Theranostics

In the field of tumor imaging and therapy, the aggregation-caused quenching (ACQ) effect of fluorescent dyes at high concentration is a great challenge. In this regard, the aggregation-induced emission luminogens (AIEgens) show great potential, since AIEgens effectively overcome the ACQ effect and have better fluorescence quantum yield, photobleaching resistance, and photosensitivity. Polyethylene glycol (PEG)-polymer is the most commonly used carrier to prepare nanoparticles (NPs). The advantage of PEGylation is that it can greatly prolong the metabolic half-life and reduce immunogenicity and toxicity. Considering that the hydrophobicity of most AIEgens hinders their application in organisms, the use of PEG-polymer encapsulation is an effective strategy to overcome this obstacle. Importantly, bioactive functional groups can be modified on PEG-polymers to enhance the biological effect of NPs. The combination of powerful AIEgens and PEG-polymers provides a new strategy for tumor imaging and therapy, which is promising for clinical application.

Targeting X box-binding protein-1 (XBP1) enhances the sensitivity of HOS osteosarcoma cells to pyropheophorbide- α methyl ester-mediated photodynamic therapy

Photodynamic therapy (PDT), utilizes a photochemical reaction between photosensitizer and light to cause cancer death by generating reactive oxygen species (ROS). X-box binding protein 1 (XBP1), a downstream product of the IRE1α-XBP1 pathway, regulates diverse target genes, including various proto-oncogenes and its overexpression was closely related to the occurrence and progression of malignant tumors. The present study was performed to explore the role of XBP1 in human osteosarcoma HOS cells treated with pyropheophorbide-α methyl ester (MPPα)-mediated photodynamic therapy (PDT) (MPPα-PDT) and its potential mechanisms. The protein IRE1α and XBP1 increased with a time-dependent manner after MPPα-PDT treated, which indicated that MPPα-PDT induced the activation of the IRE1α-XBP1 pathway in HOS cells. Besides, MPPα-PDT treated alone or combined with XBP1 knockdown could both restrain the cell viability, but the latter one has more notable effect, which indicated that XBP1 knockdown may enhance the cell inhibitory effect by MPPα-PDT. Simultaneously, the apoptotic rate measured by flow cytometry (FCM) was increased surprisedly and the expression of apoptosis proteins was increased when knockdown XBP1 under the MPPα-PDT. In addition, antioxidant-related proteins such as the Catalase and SOD1 protein levels decreased, while the intracellular ROS content increased in HOS cells when knockdown XBP1 under the MPPα-PDT. These results suggested that the mechanism of XBP1 mediating resistance in HOS cells might be related to the expression of antioxidant molecules. In summary, this study found that the IRE1α-XBP1 pathway was activated in HOS cells after MPPα-PDT treated, and furthermore, XBP1 knockdown could decrease HOS cell viability through apoptosis and enhance the anti-tumor effect of MPPα-PDT remarkably in the meantime, which related to the regulation of oxidation-antioxidant system.

A multifunctional nano-delivery system enhances the chemo-co-phototherapy of tumor multidrug resistance via mitochondrial-targeting and inhibiting P-glycoprotein-mediated efflux

Despite the excellent progress of chemotherapy and phototherapy in tumor treatment, their effectiveness on multidrug-resistant (MDR) tumors is still unsatisfactory. One of the main obstacles is drug efflux caused by P-glycoprotein in MDR cells. Herein, we developed a nano-delivery system that combines a P-glycoprotein inhibitor with chemotherapy and phototherapy to overcome MDR. Briefly, the system is prepared by the self-assembly of a ROS-triggered doxorubicin prodrug (PTD) and mitochondrial-targeted D-α-tocopherol polyethyleneglycol succinate (TPP-TPGS), in which a photoactive drug, IR780, is encapsulated (PTD/TT/IR780). PTD/TT/IR780 can target the release of TPP-TPGS, doxorubicin and IR780 at the mitochondrial site of MDR cells through ROS trigger. D-α-Tocopherol polyethyleneglycol succinate (TPGS) is a P-glycoprotein inhibitor, which will reduce the efflux of doxorubicin and IR780 from MDR cells. Under irradiation of an 808 nm near-infrared laser, IR780 generates heat and ROS, causing mitochondrial damage and prompting MDR cell apoptosis. At the same time, ROS can reduce the ATP content, which inhibits the P-glycoprotein function. In addition, an increase in the ROS generates positive feedback, allowing more nanoparticles to be cleaved and further promoting payload release in MDR cells, thereby enhancing the synergistic efficacy of chemotherapy and phototherapy. The in vitro cellular assay showed that PTD/TT/IR780 significantly inhibited MDR cell proliferation at a very low drug concentration (IC50 = 0.27 μg mL-1 doxorubicin-equivalent concentration). In vivo animal experiments based on BALB/c nude mice bearing MCF-7/ADR tumors confirmed a superior antitumor efficacy and an excellent biosafety profile. These findings demonstrate that this multifunctional nanoplatform provides a new approach for the treatment of MDR tumors.

Nonconventional luminophores: characteristics, advancements and perspectives

Nonconventional luminophores devoid of remarkable conjugates have attracted considerable attention due to their unique luminescence behaviors, updated luminescence mechanism of organics and promising applications in optoelectronic, biological and medical fields. Unlike classic luminogens consisting of molecular segments with greatly extended electron delocalization, these unorthodox luminophores generally possess nonconjugated structures based on subgroups such as ether (-O-), hydroxyl (-OH), halogens, carbonyl (CO), carboxyl (-COOH), cyano (CN), thioether (-S-), sulfoxide (SO), sulfone (OSO), phosphate, and aliphatic amine, as well as their grouped functionalities like amide, imide, anhydride and ureido. They can exhibit intriguing intrinsic luminescence, generally featuring concentration-enhanced emission, aggregation-induced emission, excitation-dependent luminescence and prevailing phosphorescence. Herein, we review the recent progress in exploring these nonconventional luminophores and discuss the current challenges and future perspectives. Notably, different mechanisms are reviewed and the clustering-triggered emission (CTE) mechanism is highlighted, which emphasizes the clustering of the above mentioned electron rich moieties and consequent electron delocalization along with conformation rigidification. The CTE mechanism seems widely applicable for diversified natural, synthetic and supramolecular systems.

Implications of photodynamic cancer therapy: an overview of PDT mechanisms basically and practically

BACKGROUND

Tumor eradication is one of the most important challengeable categories in oncological studies. In this account, besides the molecular genetics methods including cell therapy, gene therapy, immunotherapy, and general cancer therapy procedures like surgery, radiotherapy, and chemotherapy, photodynamic adjuvant therapy is of great importance. Photodynamic therapy (PDT) as a relatively noninvasive therapeutic method utilizes the irradiation of an appropriate wavelength which is absorbed by a photosensitizing agent in the presence of oxygen. In this procedure, a series of events lead to the direct death of malignant cells such as damage to the microvasculature and also the induction of a local inflammatory function. PDT has participated with other treatment modalities especially in the early stage of malignant tumors and has resulted in decreasing morbidity besides improving survival rate and quality of life. High spatial resolution of PDT has attracted considerable attention in the field of image-guided photodynamic therapy combined with chemotherapy of multidrug resistance cancers. Although PDT outcomes vary across the different tumor types, minimal natural tissue toxicity, minor systemic effects, significant reduction in long-term disease, lack of innate or acquired resistance mechanisms, and excellent cosmetic effects, as well as limb function, make it a valuable treatment option for combination therapies.

SHORT CONCLUSION

In this review article, we tried to discuss the potential of PDT in the treatment of some dermatologic and solid tumors, particularly all its important mechanisms.

Multi-functional polymeric micelles for chemotherapy-based combined cancer therapy

Currently, the therapeutic performance of traditional mono-chemotherapy on cancers remains unsatisfactory because of the tumor heterogeneity and multidrug resistance. In light of intricate tumor structures and distinct tumor microenvironments (TMEs), combinational therapeutic strategies with multiple anticancer drugs from different mechanisms can synergistically optimize the outcomes and concomitantly minimize the adverse effects during the therapy process. Extensive research on polymeric micelles (PMs) for biomedical applications has revealed the growing importance of nanomedicines for cancer therapy in the recent decade. Starting from traditional simple delivery systems, PMs have been extended to multi-faceted therapeutic strategies. Here we review and summarize the most recent advances in combinational therapy based on multifunctional PMs including a combination of multiple anticancer drugs, chemo-gene therapy, chemo-phototherapy and chemo-immunotherapy. The design approaches, action mechanisms and therapeutic applications of these nanodrugs are summarized. In addition, we highlight the opportunities and potential challenges associated with this promising field, which will provide new guidelines for advanced combinational cancer chemotherapy.

Recent Progress in Polymeric AIE-Active Drug Delivery Systems: Design and Application

Aggregation-induced emission (AIE) provides a new opportunity to overcome the drawbacks of traditional aggregation-induced quenching of chromophores. The applications of AIE-active fluorophores have spread across various fields. In particular, the employment of AIEgens in drug delivery systems (DDSs) can achieve imaging-guided therapy and pharmacodynamic monitoring. As a result, polymeric AIE-active DDSs are attracting increasing attention due to their obvious advantages, including easy fabrication and tunable optical properties by molecular design. Additionally, the design of polymeric AIE-active DDSs is a promising method for cancer therapy, antibacterial treatment, and pharmacodynamic monitoring, which indeed helps improve the effectiveness of related disease treatments and confirms its potential social importance. Here, we summarize the current available polymeric AIE-active DDSs from design to applications. In the design section, we introduce synthetic strategies and structures of AIE-active polymers, as well as responsive strategies for specific drug delivery. In the application section, typical polymeric AIE-active DDSs used for cancer therapy, bacterial treatment, and drug delivery monitoring are summarized with selected examples to elaborate on their wide applications.

Photo-Driven Delivery of 125I-Labeled Nanomicelles for Nucleus-Targeted Internal Conversion Electron-Based Cancer Therapy

As a kind of high linear energy transfer (LET) radiation, internal conversion electrons are emitted from some radionuclides, such as ¹²⁵I, triggering severe DNA damage to tumor cells when transported into the nucleus. Herein, we develop a curcumin-loaded nanomicelle composed of a photosensitizer chlorin e6 (Ce6) and amphiphilic poly(ethylene glycol) (poly(maleic anhydride-alt-1-octadecene)-poly(ethylene glycol) (C₁₈-PMH-PEG)) to deliver ¹²⁵I into the nucleus under 660 nm laser irradiation, leading to the optimized imaging-guided internal conversion electron therapy of cancer. Ce6-containing nanomicelles (Ce6-C₁₈-PEG) self-assemble with nucleus-targeted curcumin (Cur), obtaining Ce6-C₁₈-PEG/Cur nanoparticles. After labeling Cur with ¹²⁵I, Ce6-C₁₈-PEG/Cur enables single-photon emission computed tomography and fluorescence imaging of the tumor, serving as a guide for follow-up laser irradiation. Notably, the 660 nm laser-triggered photodynamic reaction of Ce6 optimizes the delivery of Ce6-C₁₈-PEG/¹²⁵I-Cur at various stages, including tumor accumulation, cellular uptake, and lysosome escape, causing plenty of ¹²⁵I-Cur to enter the nucleus. By this strategy, Ce6-C₁₈-PEG/¹²⁵I-Cur showed optimal antitumor efficacy and high biosafety in mice treated with local 660 nm laser irradiation using efficient energy deposition of internally converted electrons over short distances. Therefore, our work provides a novel strategy to optimize ¹²⁵I delivery for tumor treatment.

In Vitro Evaluation of DSPE-PEG (5000) Amine SWCNT Toxicity and Efficacy as a Novel Nanovector Candidate in Photothermal Therapy by Response Surface Methodology (RSM)

Nowadays, finding a novel, effective, biocompatible, and minimally invasive cancer treatment is of great importance. One of the most promising research fields is the development of biocompatible photothermal nanocarriers. PTT (photothermal therapy) with an NIR (near-infrared) wavelength range (700–2000 nm) would cause cell death by increasing intercellular and intracellular temperature. PTT could also be helpful to overcome drug resistance during cancer treatments. In this study, an amine derivative of phospholipid poly ethylene glycol (DSPE-PEG (5000) amine) was conjugated with SWCNTs (single-walled carbon nanotubes) to reduce their intrinsic toxicity. Toxicity studies were performed on lung, liver, and ovarian cancer cell lines that were reported to show some degree of drug resistance to cisplatin. Toxicity results suggested that DSPE-PEG (5000) amine SWCNTs might be biocompatible photothermal nanocarriers in PTT. Therefore, our next step was to investigate the effect of DSPE-PEG (5000) amine SWCNT concentration, cell treatment time, and laser fluence on the apoptosis/necrosis of SKOV3 cells post-NIR exposure by RSM and experimental design software. It was concluded that photothermal efficacy and total apoptosis would be dose-dependent in terms of DSPE-PEG (5000) amine SWCNT concentration and fluence. Optimal solutions which showed the highest apoptosis and lowest necrosis were then achieved.

Photosensitive drug delivery systems for cancer therapy: Mechanisms and applications

Over the past three decades, various photosensitive nanoparticles have been developed as potential therapies in human health, ranging from photodynamic therapy technologies that have already reached clinical use, to drug delivery systems that are still in the preclinical stages. Many of these systems are designed to achieve a high spatial and temporal on-demand drug release via phototriggerable mechanisms. This review examines the current clinical and experimental applications in cancer treatment of photosensitive drug release systems, including nanocarriers such as liposomes, micelles, polymeric nanoparticles, and hydrogels. We will focus on the three main physicochemical mechanisms of imparting photosensitivity to a delivery system: i) photochemical reactions (oxidation, cleavage, and polymerization), ii) photoisomerization, iii) and photothermal reactions. Photosensitive nanoparticles have a multitude of different applications including controlled drug release, resulting from physical/conformational changes in the delivery systems in response to light of specific wavelengths. Most of the recent research in these delivery systems has primarily focused on improving the efficacy and safety of cancer treatments such as photodynamic and photothermal therapy. Combinations of multiple treatment modalities using photosensitive nanoparticulate delivery systems have also garnered great interest in combating multi-drug resistant cancers due to their synergistic effects. Finally, the challenges and future potential of photosensitive drug delivery systems in biomedical applications is outlined.

Functionalized Selenium Nanoparticles Synergizes With Metformin to Treat Breast Cancer Cells Through Regulation of Selenoproteins

Owing to high blood sugar level and chronic inflammation, diabetes tend to cause the overproduction of free radicals in body, which will damage tissue and cells, reduce autoimmunity, and greatly increase the incidence of tumors. Selenium nanoparticles (SeNPs) exhibit high antioxidant activity with anti-tumor ability. In addition, metformin is considered as a clinical drug commonly for the treatment of stage II diabetes. Therefore, in this study, different functionalized SeNPs combined with metformin were performed to detect the feasibility for cancer therapy. The combination of Tween 80 (TW80)-SeNPs and metformin was found to have a synergistic effect on MCF-7 cells. The mechanism of this synergistic effect involved in the induction of DNA damage by affecting the generation of reactive oxygen species through selenoproteins; the upregulation of DNA-damage-related proteins including p-ATM, p-ATR, and p38; the promotion of p21 expression; and the downregulation of cyclin-dependent kinases and cyclin-related proteins causing cell cycle arrest. Furthermore, the expression of AMPK was affected, which in turn to regulate the mitochondrial membrane potential to achieve the synergistic treatment effect.

Enhanced chemo-photodynamic therapy of an enzyme-responsive prodrug in bladder cancer patient-derived xenograft models

Patient-derived xenograft (PDX) models are powerful tools for understanding cancer biology and drug discovery. In this study, a polymeric nano-sized drug delivery system poly (OEGMA)-PTX@Ce6 (NPs@Ce6) composed of a photosensitizer chlorin e6 (Ce6) and a cathepsin B-sensitive polymer-paclitaxel (PTX) prodrug was constructed. The photochemical internalization (PCI) effect and enhanced chemo-photodynamic therapy (PDT) were achieved via a two-stage light irradiation strategy. The results showed that the NPs@Ce6 had great tumor targeting and rapid cellular uptake induced by PCI, thereby producing excellent anti-tumor effects on human bladder cancer PDX models with tumor growth inhibition greater than 98%. Bioinformatics analysis revealed that the combination of PTX chemotherapy and PDT up-regulated oxidative phosphorylation and reactive oxygen species (ROS) generation, blocked cell cycle and proliferation, and down-regulated the pathways related to tumor progression, invasion and metastasis, including hypoxia, TGF-β signaling and TNF-α signaling pathways. Western blots analysis confirmed that proteins promoting apoptosis (Bax, Cleaved caspase-3, Cleaved PARP) and DNA damage (γH2A.X) were up-regulated, while those inhibiting apoptosis (Bcl-2) and mitosis (pan-actin and α/β-tubulin) were down-regulated after chemo-PDT treatment. Therefore, this stimuli-responsive polymer-PTX prodrug-based nanomedicine with combinational chemotherapy and PDT evaluated in the PDX models could be a potential candidate for bladder cancer therapy.

ROS-Responsive Selenium-Containing Carriers for Coencapsulation of Photosensitizer and Hypoxia-Activated Prodrug and Their Cellular Behaviors

The integration of hypoxia-activated chemotherapy with photodynamic therapy (PDT) has newly become a potent strategy for tumor treatment. Herein, a reactive oxygen species (ROS)-responsive drug carriers (PS@AQ4N/mPEG-b-PSe NPs) are fabricated based on the amphiphilic selenium-containing methoxy poly(ethylene glycol)-polycarbonate (mPEG-b-PSe), the hydrophobic photosensitizer (PS), and hypoxia-activated prodrug Banoxantrone (AQ4N). The obtained nanoparticles are spherical with an average diameter of 100 nm as characterized by transmission electron microscope (TEM) and dynamic laser scattering (DLS) respectively. The encapsulation efficiency of the PS and AQ4N reaches 92.83% and 51.04% at different conditions, respectively, by UV-vis spectrophotometer. It is found that the drug release is accelerated due to the good ROS responsiveness of mPEG-b-PSe and the cumulative release of AQ4N is up to 89% within 30 h. The cell test demonstrates that the nanoparticles dissociate when triggered by the ROS stimuli in the cancer cells, thus the PS is exposed to more oxygen and the ROS generation efficiency is enhanced accordingly. The consumption of oxygen during PDT leads to the increased tumor hypoxia, and subsequently activates AQ4N into cytotoxic counterpart to inhibit tumor growth. Therefore, the synergistic therapeutic efficacy demonstrates this drug delivery has great potential for antitumor therapy.

AIE material for photodynamic therapy

Photodynamic therapy (PDT) is emerging as an excellent strategy to treat different types of cancers. The advantages of using PDT over other cancer treatment modalities are owing to its non-invasive nature, spatiotemporal precession, controllable photoactivity, and least side effects. The photosensitization ability of traditional photosensitizers (PSs) are severely curtailed by aggregation-induced quenching (ACQ). On the contrary, aggregation induced emission (AIE) molecules/fluorogens (AIEgens) show enhanced fluorescence emission and high reactive oxygen species (ROS)/singlet oxygen (¹O₂) production capability in the aggregated state. These unique characteristics of AIEgens make them potential AIE-PSs for fluorescence/luminescence image-guided combination PDT. In this chapter, we discussed the strategies that are developed to synthesize small molecule-based AIE-PSs, metal complex-based AIE-PSs, and AIE-PSs with two-photon absorbance (TPA) properties, polymer-based AIE-PSs, and nanoparticles based AIE-PSs for PDT. We have also discussed the rational design of targeting peptide conjugated AIE-PSs to selective target cancer cells over normal cells. Furthermore, recent findings on nanoparticle-based combination AIE-PSs are also discussed, where the combination AIE-PSs show synergistically improved anticancer activity and overcome the drug resistance. Finally, we shed light on the recent development, ongoing challenges, and future directions for designing better AIE-PS for PDT.