Tumor Acidity-Sensitive Polymeric Vector for Active Targeted siRNA Delivery

An acid-activatable fluorouracil prodrug for colorectal cancer synergistic therapy

5-Fluorouracil has demonstrated certain efficiency in patients with colorectal cancer. However, significant side effects of use by injection are common. To address this issue defects, a reengineered 5'-deoxy-5-fluorocytidine (DFCR) based drug delivery system (POACa) is developed as a prominent tumor-selective nano-activator. Investigations demonstrate that the constructed nano-activator exhibits good biocompatibility and high therapeutic efficiency in mice with subcutaneous and orthotopic SW-480 colorectal tumors, as its activity is strictly dependent on the tumor-associated acid environment and thymidine phosphorylase. These strategies diminish the off-target toxicity and improve the specificity and sensitivity of human colorectal cancer cells to 5-Fu, obtaining potent efficiency by the combination of H2O2 mediated oxidative stress, calcium overload and 5-Fu-induced chemotherapy (the combination index is 0.11). Overall, the engineered nano-activator exhibits a high therapeutic index in vitro and in vivo. STATEMENT OF SIGNIFICANCE: In this study, we designed and prepared a pH-responsive polymer to synchronously deliver DFCR (5'-deoxy-5-fluorocytidine, a prodrug of 5-Fu), Ca2+ and H2O2. The constructed nano-activator was denoted as POACa. (1) To address the problem of premature leakage of cargo by physical embedding, our research modified the inactive prodrug DFCR through chemical bonding. (2) The activation of the prepared nano-activator was strictly dependent on the tumor-associated acid environment and thymidine phosphorylase, providing the drug delivery system with inherent safety. (3) A distinctly low combination index value (0.11) of CaO2 and DFCR indicated that POACa has a prominent tumor suppression effect by tumor calcium overload sensitized chemotherapy and H2O2 mediated cytotoxicity.

A Triterpene-Based bioactive drug delivery system for combined chemotherapy of liver cancer

Carrier materials always account for the majority particularly in nanosized formulations, which are administrated along with the active ingredient part might result in metabolism related toxicity. The usage of bioactive excipients could not only reduce the sided effect but also provide additional therapeutic effects. In the present study, a triterpene based micellar drug delivery system was developed using a bioactive solanesol derivative. Solanesylamine was prepared firstly followed by conjugating with poly (ethylene glycol) using maleic acid amide linkage. The amphiphilic drug carrier PEGylated (2-propyl-3-methylmaleic acid)-block-solanesol amine (mPEG-CDM-NH-SOL) could be formed into micelles and loaded with doxorubicin (DOX) inside. The micelles were about 112 nm in size and the drug loading content was about 5.97 wt%. An acid triggered drug release behavior was obviously observed for the DOX loaded pH-sensitive micelle mPEG-CDM-NH-SOL-DOX. While not for DOX-loaded micelles without pH-sensitivity (mPEG-NHS-NH-SOL). CCK8 assay showed that the micelles of PEGylated solanesylamines exhibited certain inhibitory effect on tumor cells at high concentration and the pH sensitive ones seemed more toxic. In vivo studies showed that the pH sensitive mPEG-CDM-NH-SOL-DOX had a superior anti-tumor effect, indicating its great potential in cancer treatment.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Bridging Smart Nanosystems with Clinically Relevant Models and Advanced Imaging for Precision Drug Delivery

Intracellular delivery of nano-drug-carriers (NDC) to specific cells, diseased regions, or solid tumors has entered the era of precision medicine that requires systematic knowledge of nano-biological interactions from multidisciplinary perspectives. To this end, this review first provides an overview of membrane-disruption methods such as electroporation, sonoporation, photoporation, microfluidic delivery, and microinjection with the merits of high-throughput and enhanced efficiency for in vitro NDC delivery. The impact of NDC characteristics including particle size, shape, charge, hydrophobicity, and elasticity on cellular uptake are elaborated and several types of NDC systems aiming for hierarchical targeting and delivery in vivo are reviewed. Emerging in vitro or ex vivo human/animal-derived pathophysiological models are further explored and highly recommended for use in NDC studies since they might mimic in vivo delivery features and fill the translational gaps from animals to humans. The exploration of modern microscopy techniques for precise nanoparticle (NP) tracking at the cellular, organ, and organismal levels informs the tailored development of NDCs for in vivo application and clinical translation. Overall, the review integrates the latest insights into smart nanosystem engineering, physiological models, imaging-based validation tools, all directed towards enhancing the precise and efficient intracellular delivery of NDCs.

Precisely Activating cGAS-STING Pathway with a Novel Peptide-Based Nanoagonist to Potentiate Immune Checkpoint Blockade Cancer Immunotherapy

As an essential intracellular immune activation pathway, the cGAS-STING pathway has attracted broad attention in cancer treatment. However, low bioavailability, nonspecificity, and adverse effects of small molecule STING agonists severely limit their therapeutic efficacy and in vivo application. In this study, a peptide-based STING agonist is first proposed, and KLA is screened out to activate the cGAS-STING pathway by promoting mitochondrial DNA (mtDNA) leakage. To precisely activate the cGAS-STING pathway and block the PD-1/PD-L1 pathway, a multi-stimuli activatable peptide nanodrug (MAPN) is developed for the effective delivery of KLA and PD-L1 antagonist peptide (CVR). With rational design, MAPN achieved the site-specific release of KLA and CVR in response to multiple endogenous stimuli, simultaneously activating the cGAS-STING pathway and blocking PD-1/PD-L1 pathway, ultimately initiating robust and durable T cell anti-tumor immunity with a tumor growth inhibition rate of 78% and extending the median survival time of B16F10 tumor-bearing mice to 40 days. Overall, antimicrobial peptides, which can promote mtDNA leakage through damaging mitochondrial membranes, may be potential alternatives for small molecule STING agonists and giving a new insight for the design of novel STING agonists. Furthermore, MAPN presents a universal delivery platform for the effective synergy of multiple peptides.

Biopolymer-based tumor microenvironment-responsive nanomedicine for targeted cancer therapy

Nanomedicine has opened up new avenues for cancer treatment by enhancing drug solubility, permeability and targeted delivery to cancer cells. Despite its numerous advantages over conventional therapies, nanomedicine may exhibit off-target drug distribution, harming nontarget regions. The increased permeation and retention effect of nanomedicine in tumor sites also has its limitations, as abnormal tumor vasculature, dense stroma structure and altered tumor microenvironment (TME) may result in limited intratumor distribution and therapeutic failure. However, TME-responsive nanomedicine has exhibited immense potential for efficient, safe and precise delivery of therapeutics utilizing stimuli specific to the TME. This review discusses the mechanistic aspects of various TME-responsive biopolymers and their application in developing various types of TME-responsive nanomedicine.

Chemically Modified Platforms for Better RNA Therapeutics

RNA-based therapies have catalyzed a revolutionary transformation in the biomedical landscape, offering unprecedented potential in disease prevention and treatment. However, despite their remarkable achievements, these therapies encounter substantial challenges including low stability, susceptibility to degradation by nucleases, and a prominent negative charge, thereby hindering further development. Chemically modified platforms have emerged as a strategic innovation, focusing on precise alterations either on the RNA moieties or their associated delivery vectors. This comprehensive review delves into these platforms, underscoring their significance in augmenting the performance and translational prospects of RNA-based therapeutics. It encompasses an in-depth analysis of various chemically modified delivery platforms that have been instrumental in propelling RNA therapeutics toward clinical utility. Moreover, the review scrutinizes the rationale behind diverse chemical modification techniques aiming at optimizing the therapeutic efficacy of RNA molecules, thereby facilitating robust disease management. Recent empirical studies corroborating the efficacy enhancement of RNA therapeutics through chemical modifications are highlighted. Conclusively, we offer profound insights into the transformative impact of chemical modifications on RNA drugs and delineates prospective trajectories for their future development and clinical integration.

Development of polypeptide-based materials toward messenger RNA delivery

Messenger RNA (mRNA)-based therapeutic agents have demonstrated significant potential in recent times, particularly in the context of the COVID-19 pandemic outbreak. As a promising prophylactic and therapeutic strategy, polypeptide-based mRNA delivery systems attract significant interest because of their low cost, simple preparation, tuneable sizes and morphology, convenient large-scale production, biocompatibility, and biodegradability. In this review, we begin with a brief discussion of the synthesis of polypeptides, followed by a review of commonly used polypeptides in mRNA delivery, including classical polypeptides and cell-penetrating peptides. Then, the challenges against mRNA delivery, including extracellular, intracellular, and clinical barriers, are discussed in detail. Finally, we highlight a range of strategies for polypeptide-based mRNA delivery, offering valuable insights into the advancement of polypeptide-based mRNA carrier development.

Efficient TNBC immunotherapy by dual reprogramming tumor-infiltrating dendritic cells and tumor-associated macrophages with stimulus-responsive miR155 nanocomplexes

Triple negative breast cancer (TNBC) remains to be a formidable adversary with high mortality and unfavorable prognosis. Tumor microenvironment comprises of various constituents, among them, tumor infiltrating dendritic cells (TIDCs) and tumor-associated macrophages (TAMs) which have been recognized as pivotal factors responsible for mediating immune responses. Overcoming the refractory properties of TIDCs and TAMs is critical for inducing a robust and sustained immune response against cancer cells. In this study, pH/ROS-responsive microRNA-155 (miR155) nanocomplexes (MiR@PCPmP NPs) were developed to reprogram TIDCs and TAMs for efficient TNBC immunotherapy. This nanoplatform was based on a pH/ROS cleavable copolymer of poly(ethylene glycol)-carboxydimethyl maleate-poly(ethyleneimine)-peroxalate ester-poly(ε-caprolactone) grafted with mannose moieties (PEG-CDM-PEI[Man]-ox-PCL) which self-assembled with miRNA to form nanocomplexes. In the tumor microenvironment, the nanocomplexes showed selective cellular uptake by TIDCs and TAMs through PEG detachment and mannose exposure, followed by efficient endosomal escape, cytosolic miR155 release, and the dual-reprogramming of TIDCs and TAMs. Our results showed that MiR@PCPmP NPs significantly improved antitumor immune responses with highly infiltrating CD8+ T cells while restraining immunosuppressive components in 4T1 tumor-bearing mice. Furthermore, the nanoparticles effectively suppressed both primary tumors and pulmonary metastatic nodules without obvious systemic toxicity. This research highlights the potential of dual-reprogramming of TIDCs and TAMs with the miR155 nanocomplexes as a promising strategy for TNBC immunotherapy, with potential for translation to other cancers with a similar microenvironment.

Enhancement of Microglia Functions by Developed Nano-Immuno-Synergist to Ameliorate Immunodeficiency for Malignant Glioma Treatment

Resident microglia are key factors in mediating immunity against brain tumors, but the microglia in malignant glioma are functionally impaired. Little immunotherapy is explored to restore microglial function against glioma. Herein, oleanolic acid (OA) (microglia "restorer") and D PPA-1 peptide (immune checkpoint blockade) are integrated on a nano-immuno-synergist (D PAM@OA) to work coordinately. The self-assembled OA core is coated with macrophage membrane for efficient blood-brain barrier penetration and microglia targeting, on which D PPA-1 peptide is attached via acid-sensitive bonds for specific release in tumor microenvironment. With the enhanced accumulation of the dual drugs in their respective action sites, D PAM@OA effectively promotes the recruitment and activation of effector T cells by inhibiting aberrant activation of Signal transducer and activator of transcription (STAT-3) pathway in microglia, and assists activated effector T cells in killing tumor cells by blocking elevated immune checkpoint proteins in malignant glioma. Eventually, as adjuvant therapy, the rationally designed nano-immuno-synergist hinders malignant glioma progression and recurrence with or without temozolomide. The work demonstrates the feasibility of a nano-formulation for microglia-based immunotherapy, which may provide a new direction for the treatment of brain tumors.

Stimuli-Responsive Nanotechnology for RNA Delivery

Ribonucleic acid (RNA) drugs have shown promising therapeutic effects for various diseases in clinical and preclinical studies, owing to their capability to regulate the expression of genes of interest or control protein synthesis. Different strategies, such as chemical modification, ligand conjugation, and nanotechnology, have contributed to the successful clinical translation of RNA medicine, including small interfering RNA (siRNA) for gene silencing and messenger RNA (mRNA) for vaccine development. Among these, nanotechnology can protect RNAs from enzymatic degradation, increase cellular uptake and cytosolic transportation, prolong systemic circulation, and improve tissue/cell targeting. Here, a focused overview of stimuli-responsive nanotechnologies for RNA delivery, which have shown unique benefits in promoting RNA bioactivity and cell/organ selectivity, is provided. Many tissue/cell-specific microenvironmental features, such as pH, enzyme, hypoxia, and redox, are utilized in designing internal stimuli-responsive RNA nanoparticles (NPs). In addition, external stimuli, such as light, magnetic field, and ultrasound, have also been used for controlling RNA release and transportation. This review summarizes a wide range of stimuli-responsive NP systems for RNA delivery, which may facilitate the development of next-generation RNA medicines.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Synergistic chemo-photo anticancer therapy by using reversible Diels-Alder dynamic covalent bond mediated polyprodrug amphiphiles and immunoactivation investigation

Highly efficient endocytosis and multi-approach integrated therapeutic tactics are important factors in oncotherapy. With the aid of thermally reversible furan-maleimide dynamic covalent bonds and the "polyprodrug amphiphiles" concept, thermo- and reduction-responsive PEG(-COOH)Fu/MI(-SS-)CPT copolymers were fabricated by the Diels-Alder (D-A) coupling of hydrophilic Fu(-COOH)-PEG and hydrophobic MI(-SS-)-CPT building blocks. The copolymers could self-assemble to form composite nanoparticles with a photothermal conversion reagent (IR780) and maintain excellent stability. In the in vitro simulated environments, the composite nanoparticles could detach Fu(-COOH)-PEG chains by a retro-D-A reaction upon near-infrared light (NIR) irradiation and reduce the size to facilitate endocytosis. Once in the intracellular environment, glutathione (GSH) could trigger a cascade reaction to release active CPT drugs to achieve chemotherapy, which could be further promoted by NIR light induced photothermal therapy. The in vivo mouse tumor model experiments demonstrated that these nanoparticles had an excellent therapeutic effect on solid tumors and inhibited their recurrence. Not only that, the synergistic chemical and optical therapy induced body immune response was also systematically evaluated; the maturation of dendritic cells, the proliferation of T cells, the increase of high mobility group box protein 1, and the decrease of immunosuppressive regulatory T cells confirmed that such synergistic therapy could effectively provide immune protection to the body. We believe such in situ generation of small-sized therapeutic units brought by a dynamically reversible D-A reaction could expand the pathway to design next generation drug delivery systems possessing superior design philosophy and excellent practice effects compared to currently available ones.

Self-Amplified Cascade Degradation and Oxidative Stress Via Rational pH Regulation of Oxidation-Responsive Poly(ferrocene) Aggregates

Precise activation of polymer nanoparticles at lesion sites is crucial to achieve favorable therapeutic efficacy. However, conventional endogenous stimuli-responsive polymer nanoparticles probably suffer from few triggers to stimulate the polymer degradation and subsequent functions. Here, we describe oxidation-responsive poly(ferrocene) amphiphiles containing phenylboronic acid ester and ferrocene as the repeating backbone units. Upon triggering by hydrogen peroxide inside the tumor cells, the phenylboronic acid ester bonds are broken and poly(ferrocene) units are degraded to afford free ferrocene and noticeable hydroxide ions. The released hydroxide ions can immediately improve the pH value within the poly(ferrocene) aggregates, and the degradation rate of the phenylboronic acid ester backbone is further promoted by the upregulated pH; thereupon, the accelerated degradation can release much more additional hydroxide ions to improve the pH, thus achieving a positive self-amplified cascade degradation of poly(ferrocene) aggregates accompanied by oxidative stress boosting and efficient cargo release. Specifically, the poly(ferrocene) aggregates can be degraded up to ∼90% within 12 h when triggered by H2O2, while ferrocene-free control nanoparticles are degraded by only 30% within 12 days. In addition, the maleimide moieties tethered in the hydrophilic corona can capture blood albumin to form an albumin-rich protein corona and significantly improve favorable tumor accumulation. The current oxidation-responsive poly(ferrocene) amphiphiles can efficiently inhibit tumors in vitro and in vivo. This work provides a proof-of-concept paradigm for self-amplified polymer degradation and concurrent oxidative stress, which is promising in actively regulated precision medicine.

Nanomedicine in cancer therapy

Cancer remains a highly lethal disease in the world. Currently, either conventional cancer therapies or modern immunotherapies are non-tumor-targeted therapeutic approaches that cannot accurately distinguish malignant cells from healthy ones, giving rise to multiple undesired side effects. Recent advances in nanotechnology, accompanied by our growing understanding of cancer biology and nano-bio interactions, have led to the development of a series of nanocarriers, which aim to improve the therapeutic efficacy while reducing off-target toxicity of the encapsulated anticancer agents through tumor tissue-, cell-, or organelle-specific targeting. However, the vast majority of nanocarriers do not possess hierarchical targeting capability, and their therapeutic indices are often compromised by either poor tumor accumulation, inefficient cellular internalization, or inaccurate subcellular localization. This Review outlines current and prospective strategies in the design of tumor tissue-, cell-, and organelle-targeted cancer nanomedicines, and highlights the latest progress in hierarchical targeting technologies that can dynamically integrate these three different stages of static tumor targeting to maximize therapeutic outcomes. Finally, we briefly discuss the current challenges and future opportunities for the clinical translation of cancer nanomedicines.

Advancements in pH-responsive nanocarriers: enhancing drug delivery for tumor therapy

INTRODUCTION

Tumors pose a significant global economic and health burden, with conventional cancer treatments lacking tumor specificity, leading to limited efficiency and undesirable side effects. Targeted tumor therapy is imminent. Tumor cells produce lactate and hydrogen ions (H+) by Warburg effect, forming an acidic tumor microenvironment (TME), which can be employed to design targeted tumor therapy. Recently, progress in nanotechnology has led to the development of pH-responsive nanocarriers, which have gathered significant attention. Under acidic tumor conditions, they exhibit targeted accumulation within tumor sites and controlled release profiles of therapeutic reagents, enabling precise tumor therapy.

AREAS COVERED

This review comprehensively summarize the principles underlying pH-responsive features, discussing various types of pH-responsive nanocarriers, their advantages, and limitations. Innovative therapeutic drugs are also examined, followed by an exploration of recent advancements in applying various pH-responsive nanocarriers as delivery systems for enhanced tumor therapy.

EXPERT OPINIONS

pH-responsive nanocarriers have garnered significant attention for their capability to achieve targeted accumulation of therapeutic agents at tumor sites and controlled drug delivery profiles, ultimately increasing the efficiency of tumor eradication. It is anticipated that the employment of pH-responsive nanocarriers will elevate the effectiveness and safety of tumor therapy, contributing to improved overall outcomes.

Inhalable siRNA Nanoparticles for Enhanced Tumor-Targeting Treatment of KRAS-Mutant Non-Small-Cell Lung Cancer

Kirsten rat sarcoma (KRAS) is the most commonly mutated oncogene in lung cancers. Gene therapy is emerging as a promising cancer treatment modality; however, the systemic administration of gene therapy has been limited by inefficient delivery to the lungs and systemic toxicity. Herein, we report a noninvasive aerosol inhalation nanoparticle (NP) system, termed "siKRAS@GCLPP NPs," to treat KRAS-mutant non-small-cell lung cancer (NSCLC). The self-assembled siKRAS@GCLPP NPs are capable of maintaining structural integrity during nebulization, with preferential distribution within the tumor-bearing lung. Inhalable siKRAS@GCLPP NPs show not only significant tumor-targeting capability but also enhanced antitumor activity in an orthotopic mouse model of human KRAS-mutant NSCLC. The nebulized delivery of siKRAS@GCLPP NPs demonstrates potent knockdown of mutated KRAS in tumor-bearing lungs without causing any observable adverse effects, exhibiting a better biosafety profile than the systemic delivery approach. The results present a promising inhaled gene therapy approach for the treatment of KRAS-mutant NSCLC and other respiratory diseases.

Efficient transfected liposomes co-loaded with pNrf2 and pirfenidone improves safe delivery for enhanced pulmonary fibrosis reversion

Pulmonary fibrosis (PF) is an interstitial lung disease with complex pathological mechanism, and there is currently a lack of therapeutics that can heal it completely. Using gene therapy with drugs provides promising therapeutic strategies for synergistically reversing PF. However, improving the intracellular accumulation and transfection efficiency of therapeutic nucleic acids is still a critical issue that urgently needs to be addressed. Herein, we developed lipid nanoparticles (PEDPs) with high transfection efficiency coloaded with pDNA of nuclear factor erythroid 2-related factor 2 (pNrf2) and pirfenidone (PFD) for PF therapy. PEDPs can penetrate biological barriers, accumulate at the target, and exert therapeutic effects, eventually alleviating the oxidative stress imbalance in type II alveolar epithelial cells (AECs II) and inhibiting myofibroblast overactivation through the synergistic effects of Nrf2 combined with PFD, thus reversing PF. In addition, we systematically engineered various liposomes (LNPs), demonstrated that reducing the polyethylene glycol (PEG) proportion could significantly improve the uptake and transfection efficiency of the LNPs, and proposed a possible mechanism for this influence. This study clearly reveals that controlling the composition ratio of PEG in PEDPs can efficiently deliver therapeutics into AECs II, improve pNrf2 transfection, and synergize with PFD in a prospective strategy to reverse PF.

Smart Nanosystems for Overcoming Multiple Biological Barriers in Cancer Nanomedicines Transport: Design Principles, Progress, and Challenges

The development of smart nanosystems, which could overcome diverse biological barriers of nanomedicine transport, has received intense scientific interest in improving the therapeutic efficacies of traditional nanomedicines. However, the reported nanosystems generally hold disparate structures and functions, and the knowledge of involved biological barriers is usually scattered. There is an imperative need for a summary of biological barriers and how these smart nanosystems conquer biological barriers, to guide the rational design of the new-generation nanomedicines. This review starts from the discussion of major biological barriers existing in nanomedicine transport, including blood circulation, tumoral accumulation and penetration, cellular uptake, drug release, and response. Design principles and recent progress of smart nanosystems in overcoming the biological barriers are overviewed. The designated physicochemical properties of nanosystems can dictate their functions in biological environments, such as protein absorption inhibition, tumor accumulation, penetration, cellular internalization, endosomal escape, and controlled release, as well as modulation of tumor cells and their resident tumor microenvironment. The challenges facing smart nanosystems on the road heading to clinical approval are discussed, followed by the proposals that could further advance the nanomedicine field. It is expected that this review will provide guidelines for the rational design of the new-generation nanomedicines for clinical use.

Peptide-based siRNA delivery system for tumor vascular normalization and gene silencing in 4T1 cells

Efficient gene delivery in an integrated drug delivery system is urgent for multimodal antitumor therapy. Herein, we describe a protocol for constructing a peptide-based siRNA delivery system to achieve tumor vascular normalization and gene silencing in 4T1 cells. We highlighted four major steps, including (1) synthesis of the chimeric peptide, (2) preparation and characterization of PA7R@siRNA micelleplexes, (3) in vitro tube formation assay and transwell cell migration assay, and (4) siRNA transfection in 4T1 cells. This delivery system is expected to be used to silence gene expression, normalize tumor vasculature, and perform other treatments based on the different peptide segments. For complete details on the use and execution of this protocol, please refer to Yi et al. (2022).1.

Repolarization of macrophages to improve sorafenib sensitivity for combination cancer therapy

Sorafenib is the first line drug for hepatocellular carcinoma (HCC) therapy. However, HCC patients usually acquire resistance to sorafenib treatment within 6 months. Recent evidences have shown that anticancer drugs with antiangiogenesis effect (e.g., sorafenib) can aggravate the hypoxia microenvironment and promote the infiltration of more tumor-associated macrophages (TAMs) into the tumor tissues. Therefore, repolarization of TAMs phenotype could be expected to not only eliminate the influence of TAMs on sorafenib lethality to HCC cells, but also provide an additional anticancer effect to achieve combination therapy. However, immune side effects remain a great challenge due to the non-specific macrophage repolarization in normal tissues. We herein employed a tumor microenvironment (TME) pH-responsive nanoplatform to concurrently transport sorafenib and modified resiquimod (R848-C16). This nanoparticle (NP) platform is made with a TME pH-responsive methoxyl-poly(ethylene glycol)-b-poly(lactic-co-glycolic acid) copolymer. After intravenous administration, the co-delivery NPs could highly accumulate in the tumor tissues and then respond to the TME pH to detach their surface PEG chains. With this PEG detachment to enhance uptake by TAMs and HCC cells, the co-delivery NPs could combinatorially inhibit HCC tumor growth via sorafenib-mediated lethality to HCC cells and R848-mediated repolarization of TAMs into tumoricidal M1-like macrophages. STATEMENT OF SIGNIFICANCE: Anticancer drugs with antiangiogenesis effect (e.g., sorafenib) can aggravate the hypoxia microenvironment and promote the infiltration of more tumor-associated macrophages (TAMs) into the tumor tissues to restrict the anticancer effect. In this work, we designed and developed a tumor microenvironment (TME) pH-responsive nanoplatform for systemic co-delivery of sorafenib and resiquimod in hepatocellular carcinoma (HCC) therapy. These co-delivery NPs show high tumor accumulation and could respond to the TME pH to enhance uptake by TAMs and HCC cells. With the sorafenib-mediated lethality to HCC cells and R848-mediated repolarization of TAMs, the co-delivery NPs show a combinational inhibition of HCC tumor growth in both xenograft and orthotopic tumor models.

Tuning the corona-core ratio of polyplex micelles for selective oligonucleotide delivery to hepatocytes or hepatic immune cells

Targeted delivery of oligonucleotides or small molecular drugs to hepatocytes, the liver's parenchymal cells, is challenging without targeting moiety due to the highly efficient mononuclear phagocyte system (MPS) of the liver. The MPS comprises Kupffer cells and specialized sinusoidal endothelial cells, efficiently clearing nanocarriers regardless of their size and surface properties. Physiologically, this non-parenchymal shield protects hepatocytes; however, these local barriers must be overcome for drug delivery. Nanocarrier structural properties strongly influence tissue penetration, in vivo pharmacokinetics, and biodistribution profile. Here we demonstrate the in vivo biodistribution of polyplex micelles formed by polyion complexation of short interfering (si)RNA with modified poly(ethylene glycol)-block-poly(allyl glycidyl ether) (PEG-b-PAGE) diblock copolymer that carries amino moieties in the side chain. The ratio between PEG corona and siRNA complexed PAGE core of polyplex micelles was chemically varied by altering the degree of polymerization of PAGE. Applying Raman-spectroscopy and dynamic in silico modeling on the polyplex micelles, we determined the corona-core ratio (CCR) and visualized the possible micellar structure with varying CCR. The results for this model system reveal that polyplex micelles with higher CCR, i.e., better PEG coverage, exclusively accumulate and thus allow passive cell-type-specific targeting towards hepatocytes, overcoming the macrophage-rich reticuloendothelial barrier of the liver.

Stimuli-Responsive Gene Delivery Nanocarriers for Cancer Therapy

Gene therapy provides a promising approach in treating cancers with high efficacy and selectivity and few adverse effects. Currently, the development of functional vectors with safety and effectiveness is the intense focus for improving the delivery of nucleic acid drugs for gene therapy. For this purpose, stimuli-responsive nanocarriers displayed strong potential in improving the overall efficiencies of gene therapy and reducing adverse effects via effective protection, prolonged blood circulation, specific tumor accumulation, and controlled release profile of nucleic acid drugs. Besides, synergistic therapy could be achieved when combined with other therapeutic regimens. This review summarizes recent advances in various stimuli-responsive nanocarriers for gene delivery. Particularly, the nanocarriers responding to endogenous stimuli including pH, reactive oxygen species, glutathione, and enzyme, etc., and exogenous stimuli including light, thermo, ultrasound, magnetic field, etc., are introduced. Finally, the future challenges and prospects of stimuli-responsive gene delivery nanocarriers toward potential clinical translation are well discussed. The major objective of this review is to present the biomedical potential of stimuli-responsive gene delivery nanocarriers for cancer therapy and provide guidance for developing novel nanoplatforms that are clinically applicable.

NIR-triggered ligand-presenting nanocarriers for enhancing synergistic photothermal-chemotherapy

Surface PEGylation of nanomedicine is effective for prolonging blood circulation time and facilitating the EPR effect, whereas the hydrophilic stealth surface inhibits effective cellular uptake and hinders active targeting. To address the dilemma, herein, a NIR light-triggered dePEGylation/ligand-presenting strategy based on thermal decomposition of azo bonds is developed, whereby Dox/Pz-IR nanoparticle is self-assembled from thermo-labile azo molecule-linked long PEG chain polymer (Pz-IR), cRGD-conjugated IR783 with short PEG chains (rP-IR) and doxorubicin. The long PEG chains could mask cRGD peptides in the blood circulation, preventing serum degradation and nonspecific interaction with normal cells. Once exposed to NIR laser, the PEG corona is stripped off owing to the rupture of azo bonds through the photothermal effect of IR783, and the masked cRGD peptides are exposed, which remarkably enhances cellular uptake by tumor cells and improves tumor accumulation. Dox/Pz-IR achieves the optimal synergy of photothermal-chemotherapy at mild temperature through progressive tumor accumulation, precisely regulated photothermal effect and NIR-PTT induced pulsated drug release. The strategy of NIR photo-driven dePEGylation/targeting offers a new approach to overcoming the "PEG dilemma", and provides a noval avenue for programmed tumor-targeted drug delivery.

Linear-like polypeptide-based micelle with pH-sensitive detachable PEG to deliver dimeric camptothecin for cancer therapy

Nano drug delivery systems have made significant progress in delivering anticancer drugs camptothecin (CPT). However, many challenges for CPT delivery remain, including low drug loading efficiency, premature drug leakage, and poor cellular internalization. Herein, we report a novel dual-sensitive polypeptide-based micelle with remarkably high drug loading of CPT for cancer therapy. This self-assembled micelle possesses the following essential components for CPT: (1) pH-sensitive PEG (OHC-PEG-CHO) for prolonging blood circulation and allowing biocompatibility by shielding the cationic micelles, which can be detached under the tumor acidic microenvironment and facilitates the cellular uptake; (2) polypeptide polylysine-polyphenylalanine (PKF) synthesized via ring-opening polymerization for micelle formation and CPT analogue loading; (3) dimeric CPT (DCPT) with redox-sensitive linker for increasing CPT loading and ensuring drug release at tumor sites. Interestingly, the linear-like morphology of PEG-PKF/DCPT micelles was able to enhance their cellular internalization when compared with the spherical blank PKF micelles. Also, the anticancer efficacy of DCPT against lung cancer cells was significantly improved by the micelle formation. In conclusion, this work provides a promising strategy facilitating the safety and effective application of CPT in cancer therapy.

Nanoparticles (NPs)-mediated systemic mRNA delivery to reverse trastuzumab resistance for effective breast cancer therapy

Monoclonal antibody-based therapy has achieved great success and is now one of the most crucial therapeutic modalities for cancer therapy. The first monoclonal antibody authorized for treating human epidermal growth receptor 2 (HER2)-positive breast cancer is trastuzumab. However, resistance to trastuzumab therapy is frequently encountered and thus significantly restricts the therapeutic outcomes. To address this issue, tumor microenvironment (TME) pH-responsive nanoparticles (NPs) were herein developed for systemic mRNA delivery to reverse the trastuzumab resistance of breast cancer (BCa). This nanoplatform is comprised of a methoxyl-poly (ethylene glycol)-b-poly (lactic-co-glycolic acid) copolymer with a TME pH-liable linker (Meo-PEG-Dlink _m -PLGA) and an amphiphilic cationic lipid that can complex PTEN mRNA via electrostatic interaction. When the long-circulating mRNA-loaded NPs build up in the tumor after being delivered intravenously, they could be efficiently internalized by tumor cells due to the TME pH-triggered PEG detachment from the NP surface. With the intracellular mRNA release to up-regulate PTEN expression, the constantly activated PI3K/Akt signaling pathway could be blocked in the trastuzumab-resistant BCa cells, thereby resulting in the reversal of trastuzumab resistance and effectively suppress the development of BCa.

Engineering Poly(ethylene glycol) Nanoparticles for Accelerated Blood Clearance Inhibition and Targeted Drug Delivery

Surface modification with poly(ethylene glycol) (PEGylation) is an effective strategy to improve the colloidal stability of nanoparticles (NPs) and is often used to minimize cellular uptake and clearance of NPs by the immune system. However, PEGylation can also trigger the accelerated blood clearance (ABC) phenomenon, which is known to reduce the circulation time of PEGylated NPs. Herein, we report the engineering of stealth PEG NPs that can avoid the ABC phenomenon and, when modified with hyaluronic acid (HA), show specific cancer cell targeting and drug delivery. PEG NPs cross-linked with disulfide bonds are prepared by using zeolitic imidazolate framework-8 NPs as templates. The reported templating strategy enables the simultaneous removal of the template and formation of PEG NPs under mild conditions (pH 5.5 buffer). Compared to PEGylated liposomes, PEG NPs avoid the secretion of anti-PEG antibodies and the presence of anti-PEG IgM and IgG did not significantly accelerate the blood clearance of PEG NPs, indicating the inhibition of the ABC effect for the PEG NPs. Functionalization of the PEG NPs with HA affords PEG NPs that retain their stealth properties against macrophages, target CD44-expressed cancer cells and, when loaded with the anticancer drug doxorubicin, effectively inhibit tumor growth. The innovation of this study lies in the engineering of PEG NPs that can circumvent the ABC phenomenon and that can be functionalized for the improved and targeted delivery of drugs.

Intelligent Drug Delivery by Peptide-Based Dual-Function Micelles

To endow the polymeric prodrug with smart properties through a safe and simple method, matrix metalloproteinase (MMPs) responsive peptide GPLGVRGDG was introduced into the block copolymer to prepare TPGS₃₃₅₀-GPLGVRGDG-DOX&DOX micelles, where TPGS₃₃₅₀ is D-α-tocopheryl polyethylene glycol 3350 succinate. During the doxorubicin delivery, the cleavage of the peptide chain triggers de-PEGylation, and the remaining VRGDG sequence was retained on the surface of the micelles, which can act as a ligand to facilitate cell uptake. Moreover, the cytotoxicity of TPGS₃₃₅₀-GPLGVRGDG-DOX&DOX micelles against 4T1 cells was significantly improved, compared with TPGS₃₃₅₀-GPLGVRG-DOX&DOX micelles and TPGS₃₃₅₀-DOX&DOX micelles. During in vivo studies, TPGS₃₃₅₀-GPLGVRGDG-DOX&DOX micelles exhibited good anticancer efficacy with long circulation in the body and more efficient accumulation at the tumor site. Therefore, TPGS₃₃₅₀-GPLGVRGDG-DOX&DOX micelles have improved antitumor activity and reduced toxic side effects. This work opens new potential for exploring the strategy of drug delivery in clinical applications.

Nanocarriers escaping from hyperacidified endo/lysosomes in cancer cells allow tumor-targeted intracellular delivery of antibodies to therapeutically inhibit c-MYC

Intracellular protein delivery is a powerful strategy for developing innovative therapeutics. Nanocarriers present great potential to deliver proteins inside cells by promoting cellular uptake and overcoming entrapment and degradation in acidic endo/lysosomal compartments. Thus, because cytosolic access is essential for eliciting the function of proteins, significant efforts have been dedicated to engineering nanocarriers with maximal endosomal escape regardless of the cell type. On the other hand, controlling the ability of nanocarriers to escape from the endo/lysosomal compartments of particular cells may offer the opportunity for enhancing delivery precision. To test this hypothesis, we developed pH-sensitive polymeric nanocarriers with adjustable endosomal escape potency for selectively reaching the cytosol of defined cancer cells with dysregulated endo/lysosomal acidification. By loading antibodies against nuclear pore complex in the nanocarriers, we demonstrated the selective delivery into the cytosol and subsequent nucleus targeting of cancer cells rather than non-cancerous cells both in vitro and in vivo. Systemically injected nanocarriers loading anti-c-MYC antibodies suppressed c-MYC in solid tumors and inhibit tumor growth without side effects, confirming the therapeutic potential of our approach. These results indicated that regulating the ability of nanocarriers to escape from endo/lysosomal compartments in particular cells is a practical approach for gaining delivery specificity.

Construction of Folate-Conjugated and pH-Responsive Cell Membrane Mimetic Mixed Micelles for Desirable DOX Release and Enhanced Tumor-Cellular Target

Smart multifunctional polymeric micelles are in urgent demand for future cancer diagnosis and therapy. In this paper, doxorubicin (DOX)-loaded folic acid (FA)-targeting and pH-responsive cell membrane mimetic mixed micelles of P(DMAEMA-co-MaPCL) (PCD) and FA-P(MPC-co-MaPCL) (PMCF) (mass ratio 5/5) were prepared by a dialysis method. The micelle size, morphology, X-ray powder diffraction (XRD), pH responsiveness, in vitro DOX release, cytotoxicity, and cellular uptake were studied in detail. The results indicated that DOX could be efficiently loaded into mixed micelles (PDMCF micelles), and the DOX-loaded mixed micelles (DOX@PDMCF micelles) exhibited a size of 150 nm and pH-responsive DOX release in an extended period. Furthermore, the DOX@PDMCF micelles could efficiently suppress the proliferation of tumor cells, HeLa and MCF-7 cells. Our data suggest that the DOX@PDMCF micelles have the potential to be applied in tumor therapy, especially for treating various folate receptor overexpressed tumors.

Recent Progress in Bio-Responsive Drug Delivery Systems for Tumor Therapy

Spatially- and/or temporally-controlled drug release has always been the pursuit of drug delivery systems (DDSs) to achieve the ideal therapeutic effect. The abnormal pathophysiological characteristics of the tumor microenvironment, including acidosis, overexpression of special enzymes, hypoxia, and high levels of ROS, GSH, and ATP, offer the possibility for the design of stimulus-responsive DDSs for controlled drug release to realize more efficient drug delivery and anti-tumor activity. With the help of these stimulus signals, responsive DDSs can realize controlled drug release more precisely within the local tumor site and decrease the injected dose and systemic toxicity. This review first describes the major pathophysiological characteristics of the tumor microenvironment, and highlights the recent cutting-edge advances in DDSs responding to the tumor pathophysiological environment for cancer therapy. Finally, the challenges and future directions of bio-responsive DDSs are discussed.

Fluorinated PEG-PEI Coated Magnetic Nanoparticles for siRNA Delivery and CXCR4 Knockdown

CXC chemokine receptor 4 (CXCR4) is a promising therapeutic target. Previous studies have shown that intracellular delivery of siRNA to knockdown CXCR4 expression in cancer cells is an effective therapeutic strategy. To prepare efficient magnetic nucleic acid carriers, it is now necessary to improve the endocytosis efficiency of PEGylated magnetic nanoparticles. In our work, Heptafluorobutyryl-polyethylene glycol-polyethyleneimine (FPP) was first prepared and then used to coat magnetic nanoparticles (MNPs) to obtain magnetic nanocarriers FPP@MNPs. The materials were characterized by 19 F-Nuclear Magnetic Resonance (NMR), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS), and dynamic light scattering (DLS). The biosecurity of FPP@MNPs was confirmed by cell viability and apoptosis experiments. Cellular uptake of FPP@MNPs and siRNA transfection enhanced by external magnetic fields were detected by fluorescence microscopy, confocal laser microscopy, and flow cytometry. The results show that the cellular uptake efficiency of FPP@MNPs was significantly improved, and transfection efficiency reached more than 90%. The knockdown of CXCR4 on the 4 T1 cell membrane was confirmed by real-time polymerase chain reaction (RT-PCR) and flow cytometry. In conclusion, the fluorinated cationic polymer-coated magnetic nanoparticles FPP@MNPs can be loaded with siRNA to reduce CXCR4 expression as well as be expected to be efficient universal siRNA carriers.

Smart Methylcellulose Hydrogels for pH-Triggered Delivery of Silver Nanoparticles

Infection is a severe complication in chronic wounds, often leading to morbidity or mortality. Current treatments rely on dressings, which frequently contain silver as a broad-spectrum antibacterial agent, although improper dosing can result in severe side effects. This work proposes a novel methylcellulose (MC)-based hydrogel designed for the topical release of silver nanoparticles (AgNPs) via an intelligent mechanism activated by the pH variations in infected wounds. A preliminary optimization of the physicochemical and rheological properties of MC hydrogels allowed defining the optimal processing conditions in terms of crosslinker (citric acid) concentration, crosslinking time, and temperature. MC/AgNPs nanocomposite hydrogels were obtained via an in situ synthesis process, exploiting MC both as a capping and reducing agent. AgNPs with a 12.2 ± 2.8 nm diameter were obtained. MC hydrogels showed a dependence of the swelling and degradation behavior on both pH and temperature and a noteworthy pH-triggered release of AgNPs (release ~10 times higher at pH 12 than pH 4). 1H-NMR analysis revealed the role of alkaline hydrolysis of the ester bonds (i.e., crosslinks) in governing the pH-responsive behavior. Overall, MC/AgNPs hydrogels represent an innovative platform for the pH-triggered release of AgNPs in an alkaline milieu.

Enhancing cancer chemo-immunotherapy by biomimetic nanogel with tumor targeting capacity and rapid drug-releasing in tumor microenvironment

In the development of chemo-immunotherapy, many efforts have been focusing on designing suitable carriers to realize the co-delivery of chemotherapeutic and immunotherapeutic with different physicochemical properties and mechanisms of action. Besides, rapid drug release at the tumor site with minimal drug degradation is also essential to facilitate the antitumor effect in a short time. Here, we reported a cancer cell membrane-coated pH-responsive nanogel (NG@M) to co-deliver chemotherapeutic paclitaxel (PTX) and immunotherapeutic agent interleukin-2 (IL-2) under mild conditions for combinational treatment of triple-negative breast cancer. In the designed nanogels, the synthetic copolymer PDEA-co-HP-β-cyclodextrin-co-Pluronic F127 and charge reversible polymer dimethylmaleic anhydride-modified polyethyleneimine endowed nanogels with excellent drug-loading capacity and rapid responsive drug-releasing behavior under acidic tumor microenvironment. Benefited from tumor homologous targeting capacity, NG@M exhibited 4.59-fold higher accumulation at the homologous tumor site than heterologous cancer cell membrane-coated NG. Rapidly released PTX and IL-2 enhanced the maturation of dendritic cells and quickly activated the antitumor immune response in situ, followed by prompted infiltration of immune effector cells. By the combined chemo-immunotherapy, enhanced antitumor effect and efficient pulmonary metastasis inhibition were achieved with a prolonged median survival rate (39 days).

Biomedical polymers: synthesis, properties, and applications

Biomedical polymers have been extensively developed for promising applications in a lot of biomedical fields, such as therapeutic medicine delivery, disease detection and diagnosis, biosensing, regenerative medicine, and disease treatment. In this review, we summarize the most recent advances in the synthesis and application of biomedical polymers, and discuss the comprehensive understanding of their property-function relationship for corresponding biomedical applications. In particular, a few burgeoning bioactive polymers, such as peptide/biomembrane/microorganism/cell-based biomedical polymers, are also introduced and highlighted as the emerging biomaterials for cancer precision therapy. Furthermore, the foreseeable challenges and outlook of the development of more efficient, healthier and safer biomedical polymers are discussed. We wish this systemic and comprehensive review on highlighting frontier progress of biomedical polymers could inspire and promote new breakthrough in fundamental research and clinical translation.

How Nanotechniques Could Vitalize the O-GlcNAcylation-Targeting Approach for Cancer Therapy

Accumulated data indicated that many types of cancers have increased protein O-GlcNAcylation at cell surface and inside cells. The aberrant O-GlcNAcylation is considered a potential therapeutic target. Although several types of compounds capable of inhibiting O-GlcNAcylation have been developed, their low solubility, poor permeability and delivery efficiency have impeded the application for in vivo and pre-clinical studies. Nanocarriers have the advantages of controllable drug release and active cancer-targeting capability. Moreover, nanoparticles can improve drug delivery efficiency and reduce the non-specific distribution in normal tissues by the enhanced permeability and retention (EPR) effect in cancer. Taking the advantage of O-GlcNAc-specific antibodies or lectins, nanoparticles could further improve their cancer-targeting capability. Although nanocarriers targeting the canonical N- and O-linked glycosylation have been extensively investigated for cancer detection and therapy, application of nanotechniques for the specific targeting of O-GlcNAcylation has not been actively pursued. This review summarizes the general features of GlcNAcylation and its alterations in cancers. Analyses are focused on the following areas: How the nanocarriers may improve the solubility and/or cell permeability of O-GlcNAc transferase (OGT) inhibitors; The modification of nanocarriers with lectins or antibodies for active targeting of O-GlcNAc; The nanocarriers-mediated co-delivery of OGT inhibitors and conventional drugs, which may lead to synergistic effects. Unsolved issues impeding the research progression on O-GlcNAcylation-targeting scheme are also discussed.

Nanocluster-Based Drug Delivery and Theranostic Systems: Towards Cancer Therapy

Over the last decades, the global life expectancy of the population has increased, and so, consequently, has the risk of cancer development. Despite the improvement in cancer therapies (e.g., drug delivery systems (DDS) and theranostics), in many cases recurrence continues to be a challenging issue. In this matter, the development of nanotechnology has led to an array of possibilities for cancer treatment. One of the most promising therapies focuses on the assembly of hierarchical structures in the form of nanoclusters, as this approach involves preparing individual building blocks while avoiding handling toxic chemicals in the presence of biomolecules. This review aims at presenting an overview of the major advances made in developing nanoclusters based on polymeric nanoparticles (PNPs) and/or inorganic NPs. The preparation methods and the features of the NPs used in the construction of the nanoclusters were described. Afterwards, the design, fabrication and properties of the two main classes of nanoclusters, namely noble-metal nanoclusters and hybrid (i.e., hetero) nanoclusters and their mode of action in cancer therapy, were summarized.

Degradable Bactericide Constructed Using a Charge-Reversal Surfactant against Plant Pathogenic Bacteria

Plant bacterial diseases are serious problems in agriculture, posing threats to global food security and the agricultural economy. Here, a degradable agricultural bactericide AMC-10 constructed using a charge-reversal surfactant, from being positively charged to negatively charged, was designed and synthesized. AMC-10 possessed high bactericidal activity toward plant pathogenic bacteria, consequently being able to inhibit the corresponding plant bacterial diseases. After degradation by water, the hydrolyzed products were nontoxic to bacteria and human cells. Such a degradable bactericide provides new ideas for the design of environmentally friendly agricultural bactericides. It is anticipated that degradable bactericides such as AMC-10 can be applied in the prevention and control of plant bacterial diseases, being less likely to produce toxicity or drug resistance.

Rational Design of Nanotherapeutics Based on the Five Features Principle for Potent Elimination of Cancer Stem Cells

Cancer stem cells (CSCs), also known as tumor initiating cells or tumor repopulating cells, which comprise only a small fraction of tumor, have received tremendous attention during the past two decades, as they are considered as the ringleader for initiation and progression of tumors, therapy resistance, metastasis, and recurrence in the clinic. Hence, eradicating CSCs is critical for successful cancer treatment. To that end, various CSC-targeting therapeutic agents have been pursued. However, these CSC-specific drugs are ineffective toward bulk cancer cells. Furthermore, these anti-CSC drugs not only eradicate CSCs but also affect conventional stem cells in normal organs or tissues. By virtue of the enhanced permeability and retention (EPR) effect, nanomaterial drug delivery systems (NDDSs) passively accumulate in tumor tissues, thereby alleviating severe side effects toward normal viscera. NDDSs can be further functionalized with CSC-specific binding molecules to promote targeted drug delivery toward CSCs. Moreover, NDDSs have unique advantages in encapsulating CSC-specific drugs and cytotoxic agents, realizing synchronized killing of CSCs and bulk cancer cells both temporally and spatially. For these reasons, leveraging nanotherapeutic strategies to target CSCs has gained tremendous attention recently.Some ten years ago, we summarized five basic features of efficient nanotherapeutics (the five features principle), which consist of long circulation, tumor accumulation, deep penetration, cellular internalization, and drug release. Based on this design rationale, we constructed several NDDSs, including nanogels with adaptive hydrophobicity, CSC-derived microparticles with tailored softness, and tumor exosome sheathed porous silicon biomimetic nanoparticles, for targeted drug delivery to tumor. To our astonishment, these NDDSs that possess the five basic features achieve decent drug delivery efficiency toward not only bulk tumor cells but more importantly CSCs. Consequently, such nanotherapeutics as-designed based on the five features principle are potent in eradicating CSCs, even with only cytotoxic drugs, for instance, doxorubicin. Furthermore, commercialized nanomedicines, such as Doxil and Abraxane, can be endowed with these five basic features by hyperbaric oxygen therapy and therefore achieve outstanding drug delivery efficiency, potent CSC elimination, and efficient cancer therapy. These studies suggest that intractable CSCs can be tackled with a material-based approach, highlight the critical role of the five features principle in designing effective nanotherapeutics, and pinpoint the significance of drug delivery efficiency in eliminating CSCs and bulk cancer cells.

Design of Smart Size-, Surface-, and Shape-Switching Nanoparticles to Improve Therapeutic Efficacy

Multiple biological barriers must be considered in the design of nanomedicines, including prolonged blood circulation, efficient accumulation at the target site, effective penetration into the target tissue, selective uptake of the nanoparticles into target cells, and successful endosomal escape. However, different particle sizes, surface chemistries, and sometimes shapes are required to achieve the desired transport properties at each step of the delivery process. In response, this review highlights recent developments in the design of switchable nanoparticles whose size, surface chemistry, shape, or a combination thereof can be altered as a function of time, a disease-specific microenvironment, and/or via an externally applied stimulus to enable improved optimization of nanoparticle properties in each step of the delivery process. The practical use of such nanoparticles in chemotherapy, bioimaging, photothermal therapy, and other applications is also discussed.

Natural Killer Cell Membrane-Cloaked Virus-Mimicking Nanogenerator with NIR-Triggered Shape Reversal and •C/•OH Storm for Synergistic Thermodynamic-Chemodynamic Therapy

Free radical-based anticancer modality has been widely applied to cancer therapies. However, it still faces challenges of low delivery efficiency and poor selectivity of free radical generation specifically toward tumors. Herein, a virus-mimicking hollow mesoporous disulfide-bridged organosilica is designed to encapsulate •C precursor 2, 2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH), which is then enclosed by tannic acid (TA)/Fe^III photothermal assembly and further cloaked by natural killer (NK) cell membrane to achieve synergistic thermodynamic-chemodynamic therapy. The nanogenerator can first evade immune surveillance via NK cell membrane "cloaking" mechanism to strongly accumulate in tumors. Interestingly, the NIR laser-induced heat can trigger NK cell membrane rupture for "shape reversal" to expose a virus-like surface to amplify the cellular uptake, and simultaneously break the azo bonds of AIPH for in situ controlled •C generation. Then upon glutathione (GSH) triggering, the nanogenerator disintegrates via disulfide-thiol exchange and efficiently generates •OH by lysosomal pH-initiated TA-Fe^III reaction; notably, the consumption of GSH can amplify oxidative stress to enhance free radical therapy by weakening the self-defense mechanism of tumor cells. It is envisioned that the NK cell membrane-cloaked virus-mimicking and NIR/GSH sequentially activated •C/•OH radical nanogenerator can provide a promising strategy for oxidative stress-based anticancer therapy.

Injectable and pH-responsive self-assembled peptide hydrogel for promoted tumor cell uptake and enhanced cancer chemotherapy

Chemotherapy is the main treatment for cancer therapy. However, its anti-tumor efficiency is always impaired by the poor bioavailability and low tumor accumulation of chemotherapeutic drugs. The variation between the tumor microenvironment and normal tissue has been recognized as an effective tool to improve drug anti-tumor efficiency. Herein, we developed an injectable, pH-responsive, in situ self-assembled drug-peptide hydrogel (MTX-KKFKFEFEF(DA)) for highly efficient local tumor chemotherapy with few side effects. The small molecule drug, methotrexate (MTX), and pH-responsive linker, 2,3-dimethylmaleic anhydride (DA), were facilely conjugated onto the chain of the KKFKFEFEF peptide via an amidation reaction. The negatively charged drug-peptide (pH 7.4) can be activated to be positive and achieve a sol-gel phase transition under an acidic microenvironment (pH 6.5) both in vitro and in vivo, resulting in highly efficient cellular uptake and endocytosis capacities. Moreover, the in vivo anti-tumor therapeutic effect revealed that the MTX-KKFKFEFEF(DA) hydrogel exhibits long-term tumor retention time, much better tumor inhibition rate and negligible side effects after intratumoral injection into breast tumor-bearing mice. Therefore, this study reveals a versatile strategy for fabricating a pH-responsive drug-peptide hydrogel to improve the chemotherapeutic efficacy of drugs in cancer treatment.

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

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

Delivery of siRNA based on engineered exosomes for glioblastoma therapy by targeting STAT3

Small interfering RNA (siRNA) has been considered as a promising strategy for treatment of glioblastoma (GBM), which is an aggressive brain disease with the poor prognosis. However, siRNA therapy for...

A pH-Responsive Nanoplatform Based on Fluorescent Conjugated Polymer Dots for Imaging-Guided Multitherapeutics Delivery and Combination Cancer Therapy

For cancer treatment, nanocarriers were designed with cationic lipids and polymers to improve the cytosolic delivery efficiency of siRNA. Though the positively charged nanocarriers showed great potential for RNA therapy, it was inevitable to generate the potential cytotoxicity. We constructed a pH-responsive nanoplatform, which co-carried siRNA and anticancer drug (hydroxycamptothecine, HCPT), to integrate gene therapy and chemotherapy for combination cancer therapy. The fluorescent conjugated polymer nanoparticles (CPNPs) modified with cell-penetrating peptides were employed as cores to carry siRNA molecules (siRNA-CPNPs) and track the biodistribution of nanotherapeutics by virtue of fluorescence. Calcium phosphate (CaP) nanocoatings were deposited on the surface of siRNA-CPNPs, followed by loading with HCPT and aptamers targeting cancer cells to obtain a targeted and tumor acid-responsive biocompatible nanoplatform. After the uptake of cancer cells, the CaP nanocoatings were decomposed in the acidic endo/lysosomes to release HCPT, and the siRNA-CPNPs were exposed to facilitate the siRNA endo/lysosome escape and cytoplasm delivery. Results obtained from both in vitro and in vivo studies in tumor inhibition expressed that the combined therapy exhibited a better therapeutic efficacy than any monotherapy.