pH-sensitive prodrug conjugated polydopamine for NIR-triggered synergistic chemo-photothermal therapy

Polydopamine Nanoparticle-Based Combined Chemotherapy and Photothermal Therapy for the Treatment of Liver Cancer

Polydopamine nanoparticles (PDA NPs) are proposed as an anti-cancer tool against hepatocellular carcinoma through the combination of near-infrared (NIR)-mediated hyperthermia and loading with a chemotherapeutic drug, sorafenib (SRF). Cell membranes isolated from a liver cancer cell line (HepG2) have been exploited for the coating of the nanoparticles (thus obtaining CM-SRF-PDA NPs), to promote homotypic targeting toward cancer cells. The selective targeting ability and the combined photothermal and chemotherapeutic activity of the CM-SRF-PDA NPs following NIR irradiation have been evaluated on cell cultures in static and dynamic conditions, besides three-dimensional culture models. Eventually, the therapeutic effectiveness of the proposed approach has also been tested ex ovo on HepG2 spheroid-grafted quail embryos. This comprehensive investigation, supported by proteomic analysis, showed the effectiveness of the proposed nanoplatform and strongly suggests further pre-clinical testing in the treatment of liver cancer.

Stimulus-Responsive Nano-Prodrug Strategies for Cancer Therapy: A Focus on Camptothecin Delivery

Camptothecin (CPT) is a highly cytotoxic molecule with excellent antitumor activity against various cancers. However, its clinical application is severely limited by poor water solubility, easy inactivation, and severe toxicity. Structural modifications and nanoformulations represent two crucial avenues for camptothecin's development. However, the potential for further structural modifications is limited, and camptothecin nanoparticles fabricated via physical loading have the drawbacks of low drug loading and leakage. Prodrug-based CPT nanoformulations have shown unique advantages, including increased drug loading, reduced burst release, improved bioavailability, and minimal toxic side effects. Stimulus-responsive CPT nano-prodrugs that respond to various endogenous or exogenous stimuli by introducing various activatable linkers to achieve spatiotemporally responsive drug release at the tumor site. This review comprehensively summarizes the latest research advances in stimulus-responsive CPT nano-prodrugs, including preparation strategies, responsive release mechanisms, and their applications in cancer therapy. Special focus is placed on the release mechanisms and characteristics of various stimulus-responsive CPT nano-prodrugs and their application in cancer treatment. Furthermore, clinical applications of CPT prodrugs are discussed. Finally, challenges and future research directions for CPT nano-prodrugs are discussed. This review to be valuable to readers engaged in prodrug research is expected.

Stimuli-sensitive polymer prodrug nanocarriers by reversible-deactivation radical polymerization

Polymer prodrugs are based on the covalent linkage of therapeutic molecules to a polymer structure which avoids the problems and limitations commonly encountered with traditional drug-loaded nanocarriers in which drugs are just physically entrapped (e.g., burst release, poor drug loadings). In the past few years, reversible-deactivation radical polymerization (RDRP) techniques have been extensively used to design tailor-made polymer prodrug nanocarriers. This synthesis strategy has received a lot of attention due to the possibility of fine tuning their structural parameters (e.g., polymer nature and macromolecular characteristics, linker nature, physico-chemical properties, functionalization, etc.), to achieve optimized drug delivery and therapeutic efficacy. In particular, adjusting the nature of the drug-polymer linker has enabled the easy synthesis of stimuli-responsive polymer prodrugs for efficient spatiotemporal drug release. In this context, this review article will give an overview of the different stimuli-sensitive polymer prodrug structures designed by RDRP techniques, with a strong focus on the synthesis strategies, the macromolecular architectures and in particular the drug-polymer linker, which governs the drug release kinetics and eventually the therapeutic effect. Their biological evaluations will also be discussed.

Shape-Regulated Photothermal-Catalytic Tumor Therapy Using Polydopamine@Pt Nanozymes with the Elicitation of an Immune Response

Recently, nanozyme-based photothermal-catalytic therapy has emerged as a promising strategy for antitumor treatment. Extensive research has focused on optimizing the catalytic activity and photothermal conversion performance of nanozymes through size, morphology, and surface property regulations. However, the biological effects of nanozymes, such as cellular uptake and cytotoxicity, resulting from their physicochemical properties, remain largely unexplored. In this study, two types of polydopamine/platinum (PDA@Pt) nanozymes, flower-like (FPDA@Pt) and mesoporous spherical-like (MPDA@Pt), to comprehensively compare their enzyme-mimicking activity, photothermal conversion capacity, and antitumor efficiency are designed. These findings revealed that FPDA@Pt exhibited superior peroxidase-like activity and higher photothermal conversion efficiency compared to MPDA@Pt. This led to enhanced production of reactive oxygen species (ROS) and increased heat generation at tumor sites. Importantly, it is observed thatthe flower-like structure of FPDA@Pt facilitated enhanced cellular uptake, leading to an increased accumulation of nanozymes within tumor cells. Furthermore, the light irradiation on tumors also triggered a series of anti-tumor immune responses, further enhancing the therapeutic efficacy. This work provides a possible design orientation for nanozyme-based photothermal-catalytic tumor therapy, highlighting the importance of considering the physicochemical properties of nanozymes to optimize their therapeutic potential in antitumor strategies.

Camptothecin-based prodrug nanomedicines for cancer therapy

Camptothecin (CPT) is a cytotoxic alkaloid that attenuates the replication of cancer cells via blocking DNA topoisomerase 1. Despite its encouraging and wide-spectrum antitumour activity, its application is significantly restricted owing to its instability, low solubility, significant toxicity, and acquired tumour cell resistance. This has resulted in the development of many CPT-based therapeutic agents, especially CPT-based nanomedicines, with improved pharmacokinetic and pharmacodynamic profiles. Specifically, smart CPT-based prodrug nanomedicines with stimuli-responsive release capacity have been extensively explored owing to the advantages such as high drug loading, improved stability, and decreased potential toxicity caused by the carrier materials in comparison with normal nanodrugs and traditional delivery systems. In this review, the potential strategies and applications of CPT-based nanoprodrugs for enhanced CPT delivery toward cancer cells are summarized. We appraise in detail the chemical structures and release mechanisms of these nanoprodrugs and guide materials chemists to develop more powerful nanomedicines that have real clinical therapeutic capacities.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Smart DNA nanogel coated polydopamine nanoparticle with high drug loading for chemo-photothermal therapy of cancer

A smart deoxyribose nucleic acid nanogel coated polydopamine nanosphere hybrid was designed for chemo-photothermal therapy of cancer. The nanohybrid showed good colloid stability, narrow size distribution, high drug loading, good biocompatibility, and high photothermal conversion efficiency, and could release the drug on desired tumor sites.

Overview of Nanoparticle-Based Approaches for the Combination of Photodynamic Therapy (PDT) and Chemotherapy at the Preclinical Stage

Simple Summary

The present review represents the outstanding and promising recent literature reports (2017–2022) on nanoparticle-based formulations developed for anticancer therapy with photodynamic therapy (PDT), photosensitizers, and chemotherapeutics. Besides brief descriptions of chemotherapeutics’ classification and of PDT mechanisms and limitations, several examples of nanosystems endowed with different responsiveness (e.g., acidic pH and reactive oxygen species) and peculiarity (e.g., tumor oxygenation capacity, active tumor targeting, and biomimetic features) are described, and for each drug combination, in vitro and in vivo results on preclinical cancer models are reported.

Abstract

The widespread diffusion of photodynamic therapy (PDT) as a clinical treatment for solid tumors is mainly limited by the patient’s adverse reaction (skin photosensivity), insufficient light penetration in deeply seated neoplastic lesions, unfavorable photosensitizers (PSs) biodistribution, and photokilling efficiency due to PS aggregation in biological environments. Despite this, recent preclinical studies reported on successful combinatorial regimes of PSs with chemotherapeutics obtained through the drugs encapsulation in multifunctional nanometric delivery systems. The aim of the present review deals with the punctual description of several nanosystems designed not only with the objective of co-transporting a PS and a chemodrug for combination therapy, but also with the goal of improving the therapeutic efficacy by facing the main critical issues of both therapies (side effects, scarce tumor oxygenation and light penetration, premature drug clearance, unspecific biodistribution, etc.). Therefore, particular attention is paid to the description of bio-responsive drugs and nanoparticles (NPs), targeted nanosystems, biomimetic approaches, and upconverting NPs, including analyzing the therapeutic efficacy of the proposed photo-chemotherapeutic regimens in in vitro and in vivo cancer models.

PDA-Based Drug Delivery Nanosystems: A Potential Approach for Glioma Treatment

Glioma is characterized by high mortality and low postoperative survival. Despite the availability of various therapeutic approaches and molecular typing, the treatment failure rate and the recurrence rate of glioma remain high. Given the limitations of existing therapeutic tools, nanotechnology has emerged as an alternative treatment option. Nanoparticles, such as polydopamine (PDA)-based nanoparticles, are embodied with reliable biodegradability, efficient drug loading rate, relatively low toxicity, considerable biocompatibility, excellent adhesion properties, precisely targeted delivery, and strong photothermal conversion properties. Therefore, they can further enhance the therapeutic effects in patients with glioma. Moreover, polydopamine contains pyrocatechol, amino and carboxyl groups, active double bonds, catechol, and other reactive groups that can react with biofunctional molecules containing amino, aldehyde, or sulfhydryl groups (main including, self-polymerization, non-covalent self-assembly, π-π stacking, electrostatic attraction interaction, chelation, coating and covalent co-assembly), which form a reversible dynamic covalent Schiff base bond that is extremely sensitive to pH values. Meanwhile, PDA has excellent adhesion capability that can be further functionally modified. Consequently, the aim of this review is to summarize the application of PDA-based NPs in glioma and to acquire insight into the therapeutic effect of the drug-loaded PDA-based nanocarriers (PDA NPs). A wealthy understanding and argument of these sides is anticipated to afford a better approach to develop more reasonable and valid PDA-based cancer nano-drug delivery systems. Finally, we discuss the expectation for the prospective application of PDA in this sphere and some individual viewpoints.

Injectable and Temperature-Sensitive Titanium Carbide-Loaded Hydrogel System for Photothermal Therapy of Breast Cancer

Recently, organic–inorganic hybrid materials have gained much attention as effective photothermal agents for cancer treatment. In this study, Pluronic F127 hydrogel-coated titanium carbide (Ti₃C₂) nanoparticles were utilized as an injectable photothermal agent. The advantages of these nanoparticles are their green synthesis and excellent photothermal efficiency. In this system, lasers were mainly used to irradiate Ti₃C₂ nanoparticles to produce a constant high temperature, which damaged cancer cells. The nanoparticles were found to be stable during storage at low temperatures for at least 2 weeks. The Ti₃C₂ nanoparticles exhibited a shuttle-shaped structure, and the hydrogels presented a loosely meshed structure. In addition, Ti₃C₂ nanoparticles did not affect the reversible temperature sensitivity of the gel, and the hydrogel did not affect the photothermal properties of Ti₃C₂ nanoparticles. The in vitro and in vivo results show that this hydrogel system can effectively inhibit tumor growth upon exposure to near-infrared irradiation with excellent biocompatibility and biosafety. The photothermal agent-embedded hydrogel is a promising photothermal therapeutic strategy for cancer treatment by enhancing the retention in vivo and elevating the local temperature in tumors.

Targeted Gold Nanohybrids Functionalized with Folate-Hydrophobic-Quaternized Pullulan Delivering Camptothecin for Enhancing Hydrophobic Anticancer Drug Efficacy

This study presented a green, facile and efficient approach for a new combination of targeted gold nanohybrids functionalized with folate-hydrophobic-quaternized pullulan delivering hydrophobic camptothecin (CPT-GNHs@FHQ-PUL) to enhance the efficacy, selectivity, and safety of these systems. New formulations of spherical CPT-GNHs@FHQ-PUL obtained by bio-inspired strategy were fully characterized by TEM, EDS, DLS, zeta-potential, UV-vis, XRD, and ATR-FTIR analyses, showing a homogeneous particles size with an average size of approximately 10.97 ± 2.29 nm. CPT was successfully loaded on multifunctional GNHs@FHQ-PUL via intermolecular interactions. Moreover, pH-responsive CPT release from newly formulated-CPT-GNHs@FHQ-PUL exhibited a faster release rate under acidic conditions. The intelligent CPT-GNHs@FHQ-PUL (IC50 = 6.2 μM) displayed a 2.82-time higher cytotoxicity against human lung cancer cells (Chago-k1) than CPT alone (IC50 = 2.2 μM), while simultaneously exhibiting less toxicity toward normal human lung cells (Wi-38). These systems also showed specific uptake by folate receptor-mediated endocytosis, exhibited excellent anticancer activity, induced the death of cells by increasing apoptosis pathway (13.97%), and arrested the cell cycle at the G0-G1 phase. The results of this study showed that the delivery of CPT by smart GNHs@FHQ-PUL systems proved to be a promising strategy for increasing its chemotherapeutic effects.

Amplification of oxidative stress with lycorine and gold-based nanocomposites for synergistic cascade cancer therapy

BACKGROUND

Despite advances of surgery and neoadjuvant chemotherapy during the past few decades, the therapeutic efficacy of current therapeutic protocol for osteosarcoma (OS) is still seriously compromised by multi-drug resistance and severe side effects. Amplification of intracellular oxidative stress is considered as an effective strategy to induce cancer cell death. The purpose of this study was to develop a novel strategy that can amplify the intracellular oxidative stress for synergistic cascade cancer therapy.

METHODS AND RESULTS

A novel nanocomposite, composed of folic acid (FA) modified mesoporous silica-coated gold nanostar (GNS@MSNs-FA) and traditional Chinese medicine lycorine (Ly), was rationally designed and developed. Under near-infrared (NIR) irradiation, the obtained GNS@MSNs-FA/Ly could promote a high level of ROS production via inducing mitochondrial dysfunction and potent endoplasmic reticulum (ER) stress. Moreover, glutathione (GSH) depletion during ER stress could reduce ROS scavenging and further enable efficient amplification of intracellular oxidative stress. Both in vitro and in vivo studies demonstrated that GNS@MSNs-FA/Ly coupled with NIR irradiation exhibited excellent antitumor efficacy without noticeable toxicity in MNNG/HOS tumor-bearing mice.

CONCLUSION

All these results demonstrated that GNS@MSNs-FA/Ly coupled with NIR irradiation could dramatically amplify the intra-tumoral oxidative stress, exhibiting excellent antitumor ability without obvious systemic toxicity. Taken together, this promising strategy provides a new avenue for the effective cancer synergetic therapy and future clinical translation.

Recent near-infrared light-activated nanomedicine toward precision cancer therapy

Light has been present throughout the history of mankind and even the universe. It is of great significance to human life, contributing to energy, agriculture, communication, and much more. In the biomedical field, light has been developed as a switch to control medical processes with minimal invasion and high spatiotemporal selectivity. During the past three years, near-infrared (NIR) light as long-wavelength light has been applied to more than 3000 achievements in biological applications due to its deep penetration depth and low phototoxicity. Remotely controlled cancer therapy usually involves the conversion of biologically inert NIR light. Thus, various materials, especially nanomaterials that can generate reactive oxygen species (ROS), ultraviolet (UV)/visual light, or thermal energy and so on under NIR illumination achieve great potential for the research of nanomedicine. Here, we offered an overview of recent advances in NIR light-activated nanomedicine for cancer therapeutic applications. NIR-light-conversion nanotechnologies for both directly triggering nanodrugs and smart drug delivery toward tumor therapy were discussed emphatically. The challenges and future trends of the use of NIR light in biomedical applications were also provided as a conclusion. We expect that this review will spark inspiration for biologists, materials scientists, pharmacologists, and chemists to fight against diseases and boost the future clinical-translational applications of NIR technology-based precision nanomedicine.

Recent Advances in Improved Anticancer Efficacies of Camptothecin Nano-Formulations: A Systematic Review

Camptothecin (CPT), a natural plant alkaloid, has indicated potent antitumor activities via targeting intracellular topoisomerase I. The promise that CPT holds in therapies is restricted through factors that include lactone ring instability and water insolubility, which limits the drug oral solubility and bioavailability in blood plasma. Novel strategies involving CPT pharmacological and low doses combined with nanoparticles have indicated potent anticancer activity in vitro and in vivo. This systematic review aims to provide a comprehensive and critical evaluation of the anticancer ability of nano-CPT in various cancers as a novel and more efficient natural compound for drug development. Studies were identified through systematic searches of PubMed, Scopus, and ScienceDirect. Eligibility checks were performed based on predefined selection criteria. Eighty-two papers were included in this systematic review. There was strong evidence for the association between antitumor activity and CPT treatment. Furthermore, studies indicated that CPT nano-formulations have higher antitumor activity in comparison to free CPT, which results in enhanced efficacy for cancer treatment. The results of our study indicate that CPT nano-formulations are a potent candidate for cancer treatment and may provide further support for the clinical application of natural antitumor agents with passive targeting of tumors in the future.

Polydopamine-Based Nanoparticles for Photothermal Therapy/Chemotherapy and their Synergistic Therapy with Autophagy Inhibitor to Promote Antitumor Treatment

Polydopamine (PDA) has attracted much attention recently due to its strong adhesion capability to most substrates. After combining with organic (such as organic metal framework, micelles, hydrogel, polypeptide copolymer) or inorganic nanomaterials (such as gold, silicon, carbon), polydopamine-based nanoparticles (PDA NPs) exhibit the merging of characteristics. Until now, the preparation methods, polymerization mechanism, and photothermal therapy (PTT) or chemotherapy (CT) applications of PDA NPs have been reported detailly. Since the PTT or CT treatment process is often accompanied by exogenous stimuli, tumor cells usually induce pro-survival autophagy to protect the cells from further damage, which will weaken the therapeutic effect. Therefore, an in-depth understanding of PDA NPs modulated PTT, CT, and autophagy is required. However, this association is rarely reviewed. Herein, we briefly described the relationship between PTT/CT, autophagy, and tumor treatment. Then, the outstanding performances of PDA NPs in PTT/CT and their combination with autophagy inhibitors for tumor synergistic therapy have been summarized. This work is expected to shed light on the multi-strategy antitumor therapy applications of PDA NPs.

Stimulus-cleavable chemistry in the field of controlled drug delivery

This review comprehensively summarises stimulus-cleavable linkers from various research areas and their cleavage mechanisms, thus provides an insightful guideline to extend their potential applications to controlled drug release from nanomaterials.

Lymph node-targeted immune-activation mediated by imiquimod-loaded mesoporous polydopamine based-nanocarriers

Toll-like receptor (TLR) agonists are the potent stimulants of innate immune system and hold promises as an adjuvant for anticancer immunotherapy. Unfortunately, most of them are limited by a prompt dissemination, and thus caused "wasted inflammation". Hence, how to restrict their action radius into lymphoid tissues is of great relevance to enhance their efficacy and concomitantly alleviates the side effects. Here, imiquimod (R837), a TLR 7 agonist, was loaded into mesoporous polydopamine (MPDA) nanocarriers with high efficiency. Moreover, its surface was modified by polyvinyl pyrrolidone (PVP) to enhance their lymphatic drainage ability. These nano-adjuvants have obvious advantages in promoting dendritic cell (DC) maturation in comparison to free R837. Moreover, their transportation and retention ability in proximal lymph nodes (LNs) were also confirmed, by which lymphatic drug exposure can be maximized to a great extent. Consequently, effective DC activation and CD8⁺ T cell responses were observed as expected by R837 released in draining LNs. This effect was further enhanced by the presence of endogenous tumor antigens from apoptosis debris induced by MPDA-based photothermal effect, and thus led to the growth inhibition of subcutaneous B16 melanomas. The results demonstrated the great potency against melanoma of the designed PVP-MPDA@R837 nano-adjuvants by combining photothermal conversion property of MPDA with lymphatic-focused immune-activation.

Synergistic combination of chemo‑phototherapy based on temozolomide/ICG‑loaded iron oxide nanoparticles for brain cancer treatment

Chemo‑photothermal therapy for cancer treatment has received increasing attention due to its selective therapeutic effects. In the present study, the anticancer effects of drug‑loaded Fe3O4 magnetic nanoparticles (MNPs) by chemo‑photothermal therapy on U‑87 MG human glioblastoma cells was investigated. Anticancer drug‑loaded Fe3O4 MNPs were prepared by loading temozolomide (TMZ) and indocyanine green (ICG), and were characterized by X‑ray diffraction, UV‑vis spectroscopy, thermal gravimetric analysis, transmission electron microscope, as well as drug‑loading capacity. Following treatment with near‑infrared (NIR) light irradiation, the administration of Fe3O4‑TMZ‑ICG MNPs resulted in the apoptosis of U‑87 MG glioblastoma cells through the generation of reactive oxygen species. Western blot analysis and reverse transcription‑quantitative polymerase chain reaction revealed that Fe3O4‑TMZ‑ICG MNPs with NIR laser irradiation lead to significantly enhanced anticancer effects on U‑87 MG glioblastoma cells through the modulation of intrinsic and extrinsic apoptosis genes, including Bcl‑2‑associated X protein, Bcl‑2, cytochrome c, caspase‑3, Fas associated via death domain and caspase‑8. These results suggest that Fe3O4‑TMZ‑ICG MNPs may be potential candidates when administered as chemo‑phototherapy for the treatment of brain cancer.

Size Matters in the Cytotoxicity of Polydopamine Nanoparticles in Different Types of Tumors

Polydopamine has acquired great relevance in the field of nanomedicine due to its physicochemical properties. Previously, it has been reported that nanoparticles synthetized from this polymer are able to decrease the viability of breast and colon tumor cells. In addition, it is well known that the size of therapeutic particles plays an essential role in their effect. As a consequence, the influence of this parameter on the cytotoxicity of polydopamine nanoparticles was studied in this work. For this purpose, polydopamine nanoparticles with three different diameters (115, 200 and 420 nm) were synthetized and characterized. Their effect on the viability of distinct sorts of human carcinomas (breast, colon, liver and lung) and stromal cells was investigated, as well as the possible mechanisms that could be responsible for such cytotoxicity. Moreover, polydopamine nanoparticles were also loaded with doxorubicin and the therapeutic action of the resulting nanosystem was analyzed. As a result, it was demonstrated that a smaller nanoparticle size is related to a more enhanced antiproliferative activity, which may be a consequence of polydopamine's affinity for iron ions. Smaller nanoparticles would be able to adsorb more lysosomal Fe3+ and, when they are loaded with doxorubicin, a synergistic effect can be achieved.

A polydopamine-based platform for anti-cancer drug delivery

Cancer is the second leading cause of death in the world with around 9.6 million deaths in 2018, approximately 70% of which occurred in the middle- and low-income countries; moreover, the economic impact of cancer is significant and escalating day by day. The total annual economic cost of cancer treatment in 2010 was estimated at approximately US$ 1.16 trillion. Researchers have explored cancer mitigation therapies such as chemo-thermal therapy, chemo-photothermal therapy and photodynamic-photothermal therapy. These combinational therapies facilitate better control on the tunability of the carrier for effectively diminishing cancer cells than individual therapies such as chemotherapy, photothermal therapy and targeted therapy. All these therapies come under novel drug delivery systems in which anti-cancer drugs attack the cancerous cells due to various stimuli (e.g. pH, thermal, UV, IR, acoustic and magnetic)-responsive properties of the anti-cancer drug carriers. Compared to conventional drug delivery systems, the novel drug delivery systems have several advantages such as targeted drug release, sustained and consistent blood levels within the therapeutic window, and decreased dosing frequency. Among the numerous polymeric carriers developed for drug delivery, polydopamine has been found to be more suitable as a carrier for these drug delivery functions due to its easy and cost-effective fabrication, excellent biocompatibility, multi-drug carrier capacity and stimuli sensitivity. Therefore, in this review, we have explored polydopamine-based carriers for anti-cancer drug delivery systems to mitigate cancer and simultaneously discussed basic synthesis routes for polydopamine.

Hyaluronic acid conjugated polydopamine functionalized mesoporous silica nanoparticles for synergistic targeted chemo-photothermal therapy

The integration of chemotherapy and photothermal therapy into one nanoplatform has attracted much attention for synergistic tumor treatment, but the practical clinical applications were usually limited by their synergistic effects and low selectivity for disease sites. To overcome these limitations, a tumor-specific and pH/NIR dual-responsive multifunctional nanocarrier coated with mussel inspired polydopamine and further conjugated with targeting molecular hyaluronic acid (HA) was designed and fabricated for synergistic targeted chemo-photothermal therapy. The synthesized versatile nanoplatform displayed strong near-infrared absorption because of the successful formation of polydopamine coating. Furthermore, the nanosystem revealed high storage capacity for drugs and pH/NIR dual-responsive release performance, which could effectively enhance the chemo-photothermal therapy effect. With this smart design, in vitro experimental results confirmed that the drug loaded multifunctional nanoparticles could be efficiently taken up by cancer cells, and exhibited remarkable tumor cell killing efficiency and excellent photothermal properties. Meanwhile, significant tumor regression in the tumor-bearing mice model was also observed due to the combination of chemotherapy and photothermal therapy. Thus, this work indicated that the simple multifunctional nanoplatform can be applied as an efficient therapeutic agent for site-specific synergistic chemo-photothermal therapy.

pH-activatable polymeric nanodrugs enhanced tumor chemo/antiangiogenic combination therapy through improving targeting drug release

It was widely accepted that polymeric nanodrugs held superiority in enhancing antitumor efficacy, reducing side effect and achieving better long-term prognosis. However, there still existed disputes that whether their therapeutic efficiency was closely related to insure effective release of hydrophobic drug located in their hydrophobic core in tumor site. In order to investigate this controversy, we constructed two polymeric nanodrugs (pH-activatable sLMWH-UOA and non-sensitive LMWH-UOA) with low molecular weight heparin (LMWH) and ursolic acid (UOA) for chemo-and anti-angiogenic combination therapy in hepatocellular carcinoma. The degradation ratio of pH-activatable sLMWH-UOA increased by 33% compared with non-sensitive LMWH-UOA in in vitro degradation study. Besides, confocal microscopy captured that sLMWH-UOA could effectively release drug in acidic microenvironment of lysosome while LMWH-UOA nearly could not. More importantly, in contrast with LMWH-UOA, sLMWH-UOA presented pH-dependent cytotoxicity, indicating that promoting drug release played a key role in enhancing the cytotoxicity of polymeric nanodrugs. Additionally, in vivo pharmacodynamic evaluation showed that although non-sensitive LMWH-UOA had benefited from enhanced tumor targeting drug delivery ability to achieve absolute advantage over free drug combination therapy in antitumor combination therapy, sLMWH-UOA could acquire further optimized combined therapeutic effect with better drug release in tumor. All above, application of tumor-triggered chemical bonds to construct polymeric nanodrugs held vast prospect for improving the therapeutic efficiency for tumor cells.

Redox-Responsive Dual Chemophotothermal Therapeutic Nanomedicine for Imaging-Guided Combinational Therapy

Chemotherapy is currently the major therapeutic method against cancer. However, chemo drugs are usually lacking in the specificity towards cancer cells over normal cells. In this study, we prepared a novel multifunctional trimeric prodrug by linking the chemo drug camptothecin (CPT) and the exceptional photostable near infrared (NIR) croconaine dye (CR) via a glutathione (GSH)-sensitive disulfide linker. Compared with CPT, our novel trimeric CR-(SS-CPT)2 is more hydrophobic and bulky, making it highly effcient to be encapsulated into biocompatible polymeric nanocarrier. The prodrug underwent rapid drug release specifically in cancer cells with high GSH concentration. The hyperthermia produced by CR upon laser irradiation could further accelerate the break of disulfide bond, which makes the release of CPT even more controllable. We further loaded the CR-(SS-CPT)2 into folate modified lipid-polymer nanoparticles, which demonstrated high in vivo tumor accumulation and retention. The biodistribution of these nanoparticles can be directly monitored in real time via NIR fluorescence and photoacoustic imaging. Under the imaging guided chemo- and photothermal- synergistic therapy, the tumors were completely ablated with no recurrence. The design not only highly enhanced the therapeutic specificity and effeciency of CPT, but also provide a "all in one" nanomedicine for imaging-guided dual modality therapy.