Charge-convertible polymers for improved tumor targeting and enhanced therapy

Tumor microenvironment activated mussel-inspired hollow mesoporous nanotheranostic for enhanced synergistic photodynamic/chemodynamic therapy

Anti-tumor therapies reliant on reactive oxygen species (ROS) as primary therapeutic agents face challenges due to a limited oxygen substrate. Photodynamic therapy (PDT) is particularly hindered by inherent hypoxia, while chemodynamic therapy (CDT) encounters obstacles from insufficient endogenous hydrogen peroxide (H2O2) levels. In this study, we engineered biodegradable tumor microenvironment (TME)-activated hollow mesoporous MnO2-based nanotheranostic agents, designated as HAMnO2A. This construct entails loading artemisinin (ART) into the cavity and surface modification with a mussel-inspired polymer ligand, namely hyaluronic acid-linked poly(ethylene glycol)-diethylenetriamine-conjugated (3,4-dihydroxyphenyl) acetic acid, and the photosensitizer Chlorin e6 (mPEG-HA-Dien-(Dhpa/Ce6)), facilitating dual-modal imaging-guided PDT/CDT synergistic therapy. In vitro experimentation revealed that HAMnO2A exhibited ideal physiological stability and enhanced cellular uptake capability via CD44-mediated endocytosis. Additionally, it was demonstrated that accelerated endo-lysosomal escape through the pH-dependent protonation of Dien. Within the acidic and highly glutathione (GSH)-rich TME, the active component of HAMnO2A, MnO2, underwent decomposition, liberating oxygen and releasing both Mn2+ and ART. This process alleviates hypoxia within the tumor region and initiates a Fenton-like reaction through the combination of ART and Mn2+, thereby enhancing the effectiveness of PDT and CDT by generating increased singlet oxygen (1O2) and hydroxyl radicals (•OH). Moreover, the presence of Mn2+ ions enabled the activation of T1-weighted magnetic resonance imaging. In vivo findings further validated that HAMnO2A displayed meaningful tumor-targeting capabilities, prolonged circulation time in the bloodstream, and outstanding efficacy in restraining tumor growth while inducing minimal damage to normal tissues. Hence, this nanoplatform serves as an efficient all-in-one solution by facilitating the integration of multiple functions, ultimately enhancing the effectiveness of tumor theranostics.

Amino-Acid-Derived Anionic Polyacrylamides with Tailored Hydrophobicity-Physicochemical Properties and Cellular Interactions

Polyanions can internalize into cells via endocytosis without any cell disruption and are therefore interesting materials for biomedical applications. In this study, amino-acid-derived polyanions with different alkyl side-chains are synthesized via postpolymerization modification of poly(pentafluorophenyl acrylate), which is synthesized via reversible addition-fragmentation chain-transfer (RAFT) polymerization, to obtain polyanions with tailored hydrophobicity and alkyl branching. The success of the reaction is verified by size-exclusion chromatography, NMR spectroscopy, and infrared spectroscopy. The hydrophobicity, surface charge, and pH dependence are investigated in detail by titrations, high-performance liquid chromatography, and partition coefficient measurements. Remarkably, the determined pK a-values for all synthesized polyanions are very similar to those of poly(acrylic acid) (pK a = 4.5), despite detectable differences in hydrophobicity. Interactions between amino-acid-derived polyanions with L929 fibroblasts reveal very slow cell association as well as accumulation of polymers in the cell membrane. Notably, the more hydrophobic amino-acid-derived polyanions show higher cell association. Our results emphasize the importance of macromolecular engineering toward ideal charge and hydrophobicity for polymer association with cell membranes and internalization. This study further highlights the potential of amino-acid-derived polymers and the diversity they provide for tailoring properties toward drug delivery applications.

Exploring the Frontier of Biopolymer-Assisted Drug Delivery: Advancements, Clinical Applications, and Future Perspectives in Cancer Nanomedicine

The burgeoning global mortality rates attributed to cancer have precipitated a critical reassessment of conventional therapeutic modalities, most notably chemotherapy, due to their pronounced adverse effects. This reassessment has instigated a paradigmatic shift towards nanomedicine, with a particular emphasis on the potentialities of biopolymer-assisted drug delivery systems. Biopolymers, distinguished by their impeccable biocompatibility, versatility, and intrinsic biomimetic properties, are rapidly ascending as formidable vectors within the cancer theragnostic arena. This review endeavors to meticulously dissect the avant-garde methodologies central to biopolymer-based nanomedicine, exploring their synthesis, functional mechanisms, and subsequent clinical ramifications. A key focus of this analysis is the pioneering roles and efficacies of lipid-based, polysaccharide, and composite nano-carriers in enhancing drug delivery, notably amplifying the enhanced permeation and retention effect. This examination is further enriched by referencing flagship nano formulations that have received FDA endorsement, thereby underscoring the transformative potential and clinical viability of biopolymer-based nanomedicines. Furthermore, this discourse illuminates groundbreaking advancements in the realm of photodynamic therapy and elucidates the implications of advanced imaging techniques in live models. Conclusively, this review not only synthesizes current research trajectories but also delineates visionary pathways for the integration of cutting-edge biomaterials in cancer treatment. It charts a course for future explorations within the dynamic domain of biopolymer-nanomedicine, thereby contributing to a deeper understanding and enhanced application of these novel therapeutic strategies.

Tumor Microenvironment-Responsive Polymer-Based RNA Delivery Systems for Cancer Treatment

Ribonucleic acid (RNA) therapeutics offer a broad prospect in cancer treatment. However, their successful application requires overcoming various physiological barriers to effectively deliver RNAs to the target sites. Currently, a number of RNA delivery systems based on polymeric nanoparticles are developed to overcome these barriers in RNA delivery. This work provides an overview of the existing RNA therapeutics for cancer gene therapy, and particularly summarizes those that are entering the clinical phase. This work then discusses the core features and latest research developments of tumor microenvironment-responsive polymer-based RNA delivery carriers which are designed based on the pathological characteristics of the tumor microenvironment. Finally, this work also proposes opportunities for the transformation of RNA therapies into cancer immunotherapy methods in clinical applications.

Hydralazine loaded nanodroplets combined with ultrasound-targeted microbubble destruction to induce pyroptosis for tumor treatment

Pyroptosis, a novel type of programmed cell death (PCD), which provides a feasible therapeutic option for the treatment of tumors. However, due to the hypermethylation of the promoter, the critical protein Gasdermin E (GSDME) is lacking in the majority of cancer cells, which cannot start the pyroptosis process and leads to dissatisfactory therapeutic effects. Additionally, the quick clearance, systemic side effects, and low concentration at the tumor site of conventional pyroptosis reagents restrict their use in clinical cancer therapy. Here, we described a combination therapy that induces tumor cell pyroptosis via the use of ultrasound-targeted microbubble destruction (UTMD) in combination with DNA demethylation. The combined application of UTMD and hydralazine-loaded nanodroplets (HYD-NDs) can lead to the rapid release of HYD (a demethylation drug), which can cause the up-regulation of GSDME expression, and produce reactive oxygen species (ROS) by UTMD to cleave up-regulated GSDME, thereby inducing pyroptosis. HYD-NDs combined with ultrasound (US) group had the strongest tumor inhibition effect, and the tumor inhibition rate was 87.15% (HYD-NDs group: 51.41 ± 3.61%, NDs + US group: 32.73%±7.72%), indicating that the strategy had a more significant synergistic anti-tumor effect. In addition, as a new drug delivery carrier, HYD-NDs have great biosafety, tumor targeting, and ultrasound imaging performance. According to the results, the combined therapy reasonably regulated the process of tumor cell pyroptosis, which offered a new strategy for optimizing the therapy of GSDME-silenced solid tumors.

Recent advances in zwitterionic nanoscale drug delivery systems to overcome biological barriers

Nanoscale drug delivery systems (nDDS) have been employed widely in enhancing the therapeutic efficacy of drugs against diseases with reduced side effects. Although several nDDS have been successfully approved for clinical use up to now, biological barriers between the administration site and the target site hinder the wider clinical adoption of nDDS in disease treatment. Polyethylene glycol (PEG)-modification (or PEGylation) has been regarded as the gold standard for stabilising nDDS in complex biological environment. However, the accelerated blood clearance (ABC) of PEGylated nDDS after repeated injections becomes great challenges for their clinical applications. Zwitterionic polymer, a novel family of anti-fouling materials, have evolved as an alternative to PEG due to their super-hydrophilicity and biocompatibility. Zwitterionic nDDS could avoid the generation of ABC phenomenon and exhibit longer blood circulation time than the PEGylated analogues. More impressively, zwitterionic nDDS have recently been shown to overcome multiple biological barriers such as nonspecific organ distribution, pressure gradients, impermeable cell membranes and lysosomal degradation without the need of any complex chemical modifications. The realization of overcoming multiple biological barriers by zwitterionic nDDS may simplify the current overly complex design of nDDS, which could facilitate their better clinical translation. Herein, we summarise the recent progress of zwitterionic nDDS at overcoming various biological barriers and analyse their underlying mechanisms. Finally, prospects and challenges are introduced to guide the rational design of zwitterionic nDDS for disease treatment.

Charge-Reversible Nanoparticles: Advanced Delivery Systems for Therapy and Diagnosis

The past two decades have witnessed a rapid progress in the development of surface charge-reversible nanoparticles (NPs) for drug delivery and diagnosis. These NPs are able to elegantly address the polycation dilemma. Converting their surface charge from negative/neutral to positive at the target site, they can substantially improve delivery of drugs and diagnostic agents. By specific stimuli like a shift in pH and redox potential, enzymes, or exogenous stimuli such as light or heat, charge reversal of NP surface can be achieved at the target site. The activated positive surface charge enhances the adhesion of NPs to target cells and facilitates cellular uptake, endosomal escape, and mitochondrial targeting. Because of these properties, the efficacy of incorporated drugs as well as the sensitivity of diagnostic agents can be essentially enhanced. Furthermore, charge-reversible NPs are shown to overcome the biofilm formed by pathogenic bacteria and to shuttle antibiotics directly to the cell membrane of these microorganisms. In this review, the up-to-date design of charge-reversible NPs and their emerging applications in drug delivery and diagnosis are highlighted.

Advancement in Biopolymer Assisted Cancer Theranostics

Applications of nanotechnology have increased the importance of research and nanocarriers, which have revolutionized the method of drug delivery to treat several diseases, including cancer, in the past few years. Cancer, one of the world's fatal diseases, has drawn scientists' attention for its multidrug resistance to various chemotherapeutic drugs. To minimize the side effects of chemotherapeutic agents on healthy cells and to develop technological advancement in drug delivery systems, scientists have developed an alternative approach to delivering chemotherapeutic drugs at the targeted site by integrating it inside the nanocarriers like synthetic polymers, nanotubes, micelles, dendrimers, magnetic nanoparticles, quantum dots (QDs), lipid nanoparticles, nano-biopolymeric substances, etc., which has shown promising results in both preclinical and clinical trials of cancer management. Besides that, nanocarriers, especially biopolymeric nanoparticles, have received much attention from researchers due to their cost-effectiveness, biodegradability, treatment efficacy, and ability to target drug delivery by crossing the blood-brain barrier. This review emphasizes the fabrication processes, the therapeutic and theragnostic applications, and the importance of different biopolymeric nanocarriers in targeting cancer both in vitro and in vivo, which conclude with the challenges and opportunities of future exploration using biopolymeric nanocarriers in onco-therapy with improved availability and reduced toxicity.

Impact of the polymer backbone chemistry on interactions of amino-acid-derived zwitterionic polymers with cells

Zwitterionic polymers are known to interact with cells and have been shown to reveal cancer cell specificity. In this work, the importance of the chemistry of the polymer backbone for the cellular specificity of amino-acid-derived polyzwitterions is demonstrated. A series of glutamic acid (Glu)-based vinyl monomers (i.e., an acrylate, a methacrylate, an acrylamide, and a methacrylamide) were prepared and used for reversible addition-fragmentation chain-transfer (RAFT) polymerisation, yielding defined polymers with narrow size distribution (Р< 1.3). All Glu-functionalised, zwitterionic polymers revealed high cytocompatibility; however, differences in cellular association and specificity were observed. In particular, the methacrylamide-derived polymers showed high association with both, breast cancer cells and non-cancerous dendritic cells and, consequently, lack specificity. In contrast, high specificity to only breast cancer cells was observed for polyacrylates, -methacrylates, and -acrylamides. Detailed analysis of the polymers revealed differences in hydrophobicity, zeta potential, and potential side chain hydrolysis, which are impacted by the polymer backbone and might be responsible for the altered the cell association of these polymers. It is shown that a slightly negative net charge is preferred over a neutral charge to retain cell specificity. This was also confirmed by association experiments in the presence of competitive amino acid transporter substrates. The affinity of slightly negatively charged Glu-derived polymers to the xCT Glu/cystine cell membrane antiporter was found to be higher than that of neutrally charged polymers. Our results emphasise the importance of the polymer backbone for the design of cell-specific polymers. This study further highlights the potential to tailor amino-acid-derived zwitterionic materials beyond their side chain functionality.

Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500-1700 nm) lanthanide nanomaterials NaGdF4:Yb3+,Er3+@NaGdF4,Nd3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

A γ-Glutamyl Transpeptidase (GGT)-Triggered Charge Reversal Drug-Delivery System for Cervical Cancer Treatment: In Vitro and In Vivo Investigation

Neutral/negatively charged nanoparticles are beneficial to reduce plasma protein adsorption and prolong their blood circulation time, while positively charged nanoparticles easily transverse the blood vessel endothelium into a tumor and easily penetrate the depth of the tumor via transcytosis. Γ-Glutamyl transpeptidase (GGT) is overexpressed on the external surface of endothelial cells of tumor blood vessels and metabolically active tumor cells. Nanocarriers modified by molecules containing γ-glutamyl moieties (such as glutathione, G-SH) can maintain a neutral/negative charge in the blood, as well as can be easily hydrolyzed by the GGT enzymes to expose the cationic surface at the tumor site, thus achieving good tumor accumulation via charge reversal. In this study, DSPE-PEG2000-GSH (DPG) was synthesized and used as a stabilizer to generate paclitaxel (PTX) nanosuspensions for the treatment of Hela cervical cancer (GGT-positive). The obtained drug-delivery system (PTX-DPG nanoparticles) was 164.6 ± 3.1 nm in diameter with a zeta potential of -9.85 ± 1.03 mV and a high drug-loaded content of 41.45 ± 0.7%. PTX-DPG NPs maintained their negative surface charge in a low concentration of GGT enzyme (0.05 U/mL), whereas they showed a significant charge-reversal property in the high-concentration solution of GGT enzyme (10 U/mL). After intravenous administration, PTX-DPG NPs mainly accumulated more in the tumor than in the liver, achieved good tumor-targetability, and significantly improved anti-tumor efficacy (68.48% vs. 24.07%, tumor inhibition rate, p < 0.05 in contrast to free PTX). This kind of GGT-triggered charge-reversal nanoparticle is promising to be a novel anti-tumor agent for the effective treatment of such GGT-positive cancers as cervical cancer.

Nanomaterials-Based Novel Immune Strategies in Clinical Translation for Cancer Therapy

Immunotherapy shows a lot of promise for addressing the problems with traditional cancer treatments. Researchers and clinicians are working to create innovative immunological techniques for cancer detection and treatment that are more selective and have lower toxicity. An emerging field in cancer therapy, immunomodulation offers patients an alternate approach to treating cancer. These therapies use the host's natural defensive systems to identify and remove malignant cells in a targeted manner. Cancer treatment is now undergoing somewhat of a revolution due to recent developments in nanotechnology. Diverse nanomaterials (NMs) have been employed to overcome the limits of conventional anti-cancer treatments such as cytotoxic, surgery, radiation, and chemotherapy. Aside from that, NMs could interact with live cells and influence immune responses. In contrast, unexpected adverse effects such as necrosis, hypersensitivity, and inflammation might result from the immune system (IS)'s interaction with NMs. Therefore, to ensure the efficacy of immunomodulatory nanomaterials, it is essential to have a comprehensive understanding of the intricate interplay that exists between the IS and NMs. This review intends to present an overview of the current achievements, challenges, and improvements in using immunomodulatory nanomaterials (iNMs) for cancer therapy, with an emphasis on elucidating the mechanisms involved in the interaction between NMs and the immune system of the host.

Charge-Convertible and Reduction-Sensitive Cholesterol-Containing Amphiphilic Copolymers for Improved Doxorubicin Delivery

For achieving successful chemotherapy against cancer, designing biocompatible drug delivery systems (DDSs) with long circulation times, high cellular endocytosis efficiency, and targeted drug release is of upmost importance. Herein, a well-defined PEG-b-P(MASSChol-co-MANBoc) block copolymer bearing redox-sensitive cholesteryl-side group was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization (with non-redox PEG-b-P(MACCChol-co-MAN-DCA) as the reference), and 1,2-dicarboxylic-cyclohexene acid (DCA) was then grafted onto the hydrophobic block to endow it with charge-convertible characteristics under a tumor microenvironment. The amphiphilic copolymer could be assembled into polymeric spherical micelles (SSMCs) with polyethylene glycol (PEG) as the corona/shell, and anti-cancer drug doxorubicin (DOX) was successfully encapsulated into the micellar core via strong hydrophobic and electrostatic interactions. This nanocarrier showed high stability in the physiological environment and demonstrated "smart" surface charge conversion from negative to positive in the slightly acidic environment of tumor tissues (pH 6.5~6.8), as determined by dynamic light scattering (DLS). Moreover, the cleavage of a disulfide bond linking the cholesterol grafts under an intracellular redox environment (10 mM GSH) resulted in micellar dissociation and accelerated drug release, with the non-redox-responsive micelles (CCMCs) as the control. Additionally, a cellular endocytosis and tumor proliferation inhibition study against MCF-7 tumor cells demonstrated the enhanced endocytosis and tumor cell inhibitory efficiency of dual-responsive SSMCs/DOX nanomedicines, revealing potentials as multifunctional nanoplatforms for effective oncology treatment.

Delivering the Promise of Gene Therapy with Nanomedicines in Treating Central Nervous System Diseases

Central Nervous System (CNS) diseases, such as Alzheimer's diseases (AD), Parkinson's Diseases (PD), brain tumors, Huntington's disease (HD), and stroke, still remain difficult to treat by the conventional molecular drugs. In recent years, various gene therapies have come into the spotlight as versatile therapeutics providing the potential to prevent and treat these diseases. Despite the significant progress that has undoubtedly been achieved in terms of the design and modification of genetic modulators with desired potency and minimized unwanted immune responses, the efficient and safe in vivo delivery of gene therapies still poses major translational challenges. Various non-viral nanomedicines have been recently explored to circumvent this limitation. In this review, an overview of gene therapies for CNS diseases is provided and describes recent advances in the development of nanomedicines, including their unique characteristics, chemical modifications, bioconjugations, and the specific applications that those nanomedicines are harnessed to deliver gene therapies.

Preparation and application of pH-responsive drug delivery systems

Microenvironment-responsive drug delivery systems (DDSs) can achieve targeted drug delivery, reduce drug side effects and improve drug efficacies. Among them, pH-responsive DDSs have gained popularity since the pH in the diseased tissues such as cancer, bacterial infection and inflammation differs from a physiological pH of 7.4 and this difference could be harnessed for DDSs to release encapsulated drugs specifically to these diseased tissues. A variety of synthetic approaches have been developed to prepare pH-sensitive DDSs, including introduction of a variety of pH-sensitive chemical bonds or protonated/deprotonated chemical groups. A myriad of nano DDSs have been explored to be pH-responsive, including liposomes, micelles, hydrogels, dendritic macromolecules and organic-inorganic hybrid nanoparticles, and micron level microspheres. The prodrugs from drug-loaded pH-sensitive nano DDSs have been applied in research on anticancer therapy and diagnosis of cancer, inflammation, antibacterial infection, and neurological diseases. We have systematically summarized synthesis strategies of pH-stimulating DDSs, illustrated commonly used and recently developed nanocarriers for these DDSs and covered their potential in different biomedical applications, which may spark new ideas for the development and application of pH-sensitive nano DDSs.

Charge Reversal Polypyrrole Nanocomplex-Mediated Gene Delivery and Photothermal Therapy for Effectively Treating Papillary Thyroid Cancer and Inhibiting Lymphatic Metastasis

As a traditional treatment for papillary thyroid cancer (PTC), surgical resection of diseased tissues often brings lots of inconveniences to patients, and the tumor recurrence and metastasis are difficult to avoid. Herein, we developed a gene and photothermal combined therapy nanosystem based on a polypyrrole (Ppy)-poly(ethylene imine)-siILK nanocomplex (PPR_ILK) to achieve minimally invasive ablation and lymphatic metastasis inhibition in PTC simultaneously. In this system, gelatin-stabilized Ppy mainly acted as a photothermal- and photoacoustic (PA)-responsive nanomaterial and contributed to its well-behaved photosensitivity in the near-infrared region. Moreover, gelatin-stabilized Ppy possessed a charge reversal function, facilitating the tight conjunction of siILK gene at physiological pH (7.35-7.45) and its automatic release into acidic lysosomes (pH 4.0-5.5); the proton sponge effect generated during this process further facilitated the escape of siILK from lysosomes to the cytoplasm and played its role in inhibiting PTC proliferation and lymphatic metastasis. With the guidance of fluorescence and PA bimodal imaging, gene delivery and Ppy location in tumor regions could be clearly observed. As a result, tumors were completely eradicated by photothermal therapy, and the recurrences and metastases were obviously restrained by siILK.

Tailoring the physicochemical properties of nanomaterials for immunomodulation

Immunomodulation is poised to revolutionize the treatment of cancer, autoimmune diseases, and many other inflammation-related disorders. The immune system in these conditions can be either activated or suppressed by nanocarriers loaded with bioactive molecules. Although immunomodulation via these therapeutics has long been recognized, and a broad range of nanocarriers have been designed to accommodate varied usages, less studies have focused on the effects of nanomaterial physicochemical properties on immune responses, especially the immunity altered by nanocarrier materials alone. Conclusions are sometimes seemly inconsistent due to the complexities of nanomaterials and the immune system. An in-depth understanding of the nanocarrier-induced immune responses is essential for clinical applications. In this review, we summarize recent studies of the immune responses influenced by nanomaterial physicochemical properties with an emphasis on the intrinsic features of nanomaterials that modulate the innate and adaptive immunities. We then provide our perspectives on the design of nanomaterials for immunomodulation.

Cascade-Responsive Hierarchical Nanosystems for Multisite Specific Drug Exposure and Boosted Chemoimmunotherapy

The precise delivery of multiple drugs to their distinct destinations plays a significant role in safe and efficient combination therapy; however, it is highly challenging to simultaneously realize the targets and overcome the intricate biological hindrances using an all-in-one nanosystem. Herein, a cascade-responsive hierarchical nanosystem containing checkpoint inhibitor anti-PD-L1 antibody (αPD-L1) and paclitaxel (PTX) is developed for spatially programed delivery of multiple drugs and simultaneously overcoming biological pathway barriers. The hierarchical nanoparticles (MPH-NP@A) are composed of pH-sensitive hyaluronic acid-acetal-PTX prodrugs (HA-ace-PTX(SH)) chaperoned by αPD-L1 and metalloproteinase-9 (MMP-9)-responsive outer shells, which could be fast cleaved to release αPD-L1 in the tumor microenvironment (TME). The released αPD-L1 sequentially synergizes with PTX released in the cytoplasm for boosted chemoimmunotherapy due to direct killing of PTX and intensified immune responses through immunogenic cell death (ICD) as well as suppression of immune escape by blocking the PD-1/PD-L1 axis. The in vitro and in vivo studies demonstrate that MPH-NP@A evokes distinct ICD, enhanced cytotoxic T lymphocytes infiltration, as well as significant tumor inhibition, thus providing a promising therapeutic nano-platform for safe and efficient combination therapy.

Self-assembled ternary hybrid nanodrugs for overcoming tumor resistance and metastasis

Traditional chemotherapy exhibits a certain therapeutic effect toward malignant cancer, but easily induce tumor multidrug resistance (MDR), thereby resulting in the progress of tumor recurrence or metastasis. In this work, we deigned ternary hybrid nanodrugs (PEI/DOX@CXB-NPs) to simultaneously combat against tumor MDR and metastasis. In vitro results demonstrate this hybrid nanodrugs could efficiently increase cellular uptake at pH 6.8 by the charge reversal, break lysosomal sequestration by the proton sponge effect and trigger drugs release by intracellular GSH, eventually leading to higher drugs accumulation and cell-killing in drug-sensitive/resistant cells. In vivo evaluation revealed that this nanodrugs could significantly inhibit MDR tumor growth and simultaneously prevent A549 tumor liver/lung metastasis owing to the specifically drugs accumulation. Mechanism studies further verified that hybrid nanodrugs were capable of down-regulating the expression of MDR or metastasis-associated proteins, lead to the enhanced anti-MDR and anti-metastasis effect. As a result, the multiple combination strategy provided an option for effective cancer treatment, which could be potentially extended to other therapeutic agents or further use in clinical test.

In vitro/vivo antitumor study of modified-chitosan/carboxymethyl chitosan "boosted" charge-reversal nanoformulation

Major obstacles in the development of nanoformulations as efficient drug delivery systems are the rapid clearance from blood circulation and lysosomal entrapment. To overcome these problems, a polysaccharide-based core-shell type charge-switchable nanoformulation (CS-LA-DMMA/CMCS/PAMAM@DOX) is constructed to improve antitumor efficacy of DOX. By applying carboxymethyl chitosan (CMCS) as bridge polymer and negatively charged chitosan-derivative as outer shell, the stability and pH-sensitivity of this nanoformulation is promisingly enhanced. Furthermore, the positively charged PAMAM@DOX could escape from lysosomes via "proton sponge effect" and "cationic-anionic interaction with lysosome membranes". Admirable cellular uptake and high apoptosis/necrosis rate were detected in this study. In vitro assays demonstrate that the CS-LA-DMMA/CMCS/PAMAM@DOX was internalized into HepG2 cells predominantly via the clathrin-mediated endocytosis pathway. Excitingly, in vivo studies showed that high accumulation of CS-LA-DMMA/CMCS/PAMAM@DOX in tumor tissue led to enhanced tumor inhibition. Compared with free DOX, the tumor inhibition rate of nanoformulation was improved up to 226%.

TMTP1-Modified, Tumor Microenvironment Responsive Nanoparticles Co-Deliver Cisplatin and Paclitaxel Prodrugs for Effective Cervical Cancer Therapy

Background and Purpose

Cisplatin-paclitaxel (TP) combination chemotherapy as the first-line therapy for numerous cancers is hindered by its inadequate accumulation in tumors and severe side effects resulting from non-specific distribution. The aim of this study is to explore whether TMTP1-modified, cisplatin and paclitaxel prodrugs co-loaded nanodrug could improve cervical cancer chemotherapy and relieve its side effects through active and passive tumor targeting accumulation and controlled drug release.

Methods

TDNP, with capacities of active targeting for tumors and controlled drug release, was prepared to co-deliver cisplatin and paclitaxel prodrugs. The characteristics were investigated, including the diameter, surface zeta potential, stability and tumor microenvironment (TME) dependent drug release profiles. Cellular uptake, cytotoxicity, drug accumulation in tumors, antitumor effects and safety analysis were evaluated in vitro and in vivo.

Results

The oxidized cisplatin and the paclitaxel linked to the polymer achieved a high loading effciency of over 80% and TME-dependent sustained drug release. Moreover, TMTP1 modification enhanced cellular uptake of TDNP and further improved the cytotoxicity of TDNP in vitro. In vivo, TDNP showed an extended blood circulation and increased accumulation in SiHa xenograft models with the aid of TMTP1. More importantly, TDNP controlled tumor growth without life-threatening side effects.

Conclusion

Our study provided a novel TP co-delivery platform for targeted chemotherapy of cervical cancer, which was promising to improve the therapeutic effcacy of TP and may also have application in other tumors.

Ultrasound responsive erythrocyte membrane-derived hybrid nanovesicles with controlled drug release for tumor therapy

An ultrasound responsive erythrocyte membrane-derived hybrid nanovesicle drug delivery system (DOX/HMME@FA-NL) is constructed by the membrane fusion functionalization strategy for controlled drug release and enhanced tumor therapy. The reliability and effectiveness of the membrane fusion strategy are confirmed through characterization of the particle size and zeta potential, Förster energy resonance transfer and fluorescence co-localization analyses. The DOX/HMME@FA-NL could be triggered for reactive oxygen species (ROS) generation under ultrasound stimulation. And the unsaturated phospholipids in DOX/HMME@FA-NL can be oxidized by ROS, leading to the destruction of the structure of the hybrid membrane to achieve the controlled release of drugs, thereby enhancing their tumor cell killing effect. Besides, the linkage of the folate targeting group also enhances the tumor targeting ability of DOX/HMME@FA-NL. H22 tumor-bearing mice were intravenously injected with DOX/HMME@FA-NL and treated with ultrasound, they achieved better than expected tumor sonodynamic response treatment effects.

Recent progress on charge-reversal polymeric nanocarriers for cancer treatments

Nanocarriers (NCs) for delivery anticancer therapeutics have been under development for decades. Although great progress has been achieved, the clinic translation is still in the infancy. The key challenge lies in the biological barriers which lie between the NCs and the target spots, including blood circulation, tumor penetration, cellular uptake, endo-/lysosomal escape, intracellular therapeutics release and organelle targeting. Each barrier has its own distinctive microenvironment and requires different surface charge. To address this challenge, charge-reversal polymeric NCs have been a hot topic, which are capable of overcoming each delivery barrier, by reversing their charges in response to certain biological stimuli in the tumor microenvironment. In this review, the triggering mechanisms of charge reversal, including pH, enzyme and redox approaches are summarized. Then the corresponding design principles of charge-reversal NCs for each delivery barrier are discussed. More importantly, the limitations and future prospects of charge-reversal NCs in clinical applications are proposed.

pH and ROS sequentially responsive podophyllotoxin prodrug micelles with surface charge-switchable and self-amplification drug release for combating multidrug resistance cancer

Multidrug resistance (MDR) is one of the main reasons for tumor chemotherapy failure. Podophyllotoxin (PPT) has been reported that can suppress MDR cancer cell growth; however, effective delivery of PPT to MDR cancer cells is challenged by cascaded bio-barriers. To effectively deliver PPT to MDR cancer cells, a PPT polymeric prodrug micelle (PCDMA) with the charge-conversion capability and self-acceleration drug release function are fabricated, which is composed of a pH and reactive oxygen species (ROS) sequentially responsive PPT-polymeric prodrug and an ROS generation agent, cucurbitacin B (CuB). After reach to tumor tissue, the surface charge of PCDMA could rapidly reverse to positive in the tumor extracellular environment to promote cellular uptake. Subsequently, the PCDMA could be degraded to release PPT and CuB in response to an intracellular high ROS condition. The released CuB is competent for generating ROS, which in turn accelerates the release of PPT and CuB. Eventually, the released PPT could kill MDR cancer cells. The in vitro and in vivo studies demonstrated that PCDMA was effectively internalized by cancer cells and produces massive ROS intracellular, rapid release drug, and effectively overcame MDR compared with the control cells, due to the tumor-specific weakly acidic and ROS-rich environment. Our results suggest that the pH/ROS dual-responsive PCDMA micelles with surface charge-reversal and self-amplifying ROS-response drug release provide an excellent platform for potential MDR cancer treatment.

Active-targeting and acid-sensitive pluronic prodrug micelles for efficiently overcoming MDR in breast cancer

Multidrug resistance (MDR) seriously hinders therapeutic efficacy in clinical cancer treatment. Herein, we reported new polymeric prodrug micelles with tumor-targeting and acid-sensitivity properties based on two different pluronic copolymers (F127 and P123) for enhancing tumor MDR reversal and chemotherapy efficiency in breast cancer. Hybrid micelles were composed of phenylboric acid (PBA)-modified F127 (active-targeting group) and doxorubicin (DOX)-grafted P123 (prodrug groups), which were named as FBP-CAD. FBP-CAD exhibited good stability in a neutral environment and accelerated drug release under mildly acidic conditions by the cleavage of β-carboxylic amides bonds. In vitro studies demonstrated that FBP-CAD significantly increased cellular uptake and drug concentration in MCF-7/ADR cells through the homing ability of PBA and the anti-MDR effect of P123. In vivo testing further indicated that hybrid micelles facilitated drug accumulation at tumor sites as well as reduced side effects to normal organs. The synergistic effect of active-targeting and MDR-reversal leads to the highest tumor growth inhibition (TGI 78.2%). Thus, these multifunctional micelles provide a feasible approach in nanomedicine for resistant-cancer treatment.

pH-Responsive expandable polycarbonate–doxorubicin conjugate nanoparticles for fast intracellular drug release

Nanoparticles with tertiary amines were prepared, which are pH-responsive, expanding to expose the acid-sensitive chemical bond and accelerating drug release.

A pH-activated charge convertible quantum dot as a novel nanocarrier for targeted protein delivery and real-time cancer cell imaging

The rapid developments of nanocarriers based on quantum dots (QDs) have been confirmed to show substantial promise for drug delivery and bioimaging. However, optimal QDs-based nanocarriers still need to have their controlled behavior in vitro and in vivo and decrease heavy metal-associated cytotoxicity. Herein, a pH-activated charge convertible QD-based nanocarrier was fabricated by capping multifunctional polypeptide ligands (mPEG-block-poly(ethylenediamine-dihydrolipoic acid-2,3-dimethylmaleic anhydride)-L-glutamate, PEG-P(ED-DLA-DMA)LG) onto the surface of core/multishell CdSe@ZnS/ZnS QD by means of a ligand exchange strategy, followed by uploading of cytochrome C (CC) (CC-loaded QD-PEG-P(ED-DLA-DMA)LG) via electrostatic interactions, in which QDs that were water-soluble and protein-loading were perfectly integrated. That is, the CC-loaded QD-PEG-P(ED-DLA-DMA)LG inherited excellent fluorescence properties from CdSe@ZnS/ZnS QD for real-time imaging, as well as tumor-microenvironment sensitivities from PEG-P(ED-DLA-DMA)LG for enhanced cellular uptake and CC release. Experimental results verified that the QD-PEG-P(ED-DLA-DMA)LG showed enhanced internalization, rapid endo/lysosomal escape, and supplied legible real-time imaging for lung carcinoma cells. Furthermore, pH-triggered charge-convertible ability enabled the QD-PEG-P(ED-DLA-DMA)LG-CC to effectively kill cancer cells better than did the control groups. Hence, constructing smart nanocomposites by facile ligand-exchange strategy is beneficial to QD-based nanocarrier for tumor-targeting cancer therapy.

Lapatinib-loaded acidity-triggered charge switchable polycarbonate-doxorubicin conjugate micelles for synergistic breast cancer chemotherapy

Stimulus-responsive nanosystem is a powerful method to improve the bioavailability and reduce the side effects of anticancer agents. In the present study, a customized dual pH-responsive micellar nanoplatform (DOX+LAP-M) based on polycarbonate-doxorubicin conjugate micelles was prepared to co-deliver the chemotherapeutic agent lapatinib for inhibiting tumor growth and metastasis. DOX+LAP-M micelles with spherical morphology had a size of ~112 nm and had an initial negative surface charge, which are favorable characteristics for long-term circulation in the blood. Once the micelles accumulated in tumor tissues, the intrinsic tumor extracellular acidity triggered the charge switch of DOX+LAP-M micelles from -1 to 9 mV, thereby facilitating cell internalization and tumor penetration. Subsequently, the pH-sensitive micellar core accelerated the release of doxorubicin and lapatinib in the acidic intracellular environment. DOX+LAP-M micelles effectively inhibited the proliferation, migration, and invasion of 4T1 cells in vitro; furthermore, the administration of DOX+LAP-M micelles in 4T1 xenograft-bearing mice suppressed solid tumor growth with an inhibitory rate of 90.2% and significantly decreased pulmonary metastatic nodules, without significant systemic toxicity. This multifunctional micellar system has high potential for clinical cancer therapy.

Dual activatable self-assembled nanotheranostics for bioimaging and photodynamic therapy

Multifunctional nanosystems that can transport therapeutic and diagnostic agents into tumor sites and activate their respective functions via tumor-microenvironment recognition are highly desirable for clinical applications. We fabricated pH and redox dual-activatable self-assembled nanotheranostics (named as DA-SNs) via coordination-driven self-assembly of chlorin e6 (Ce6) disulfide-linked pH sensitive polymer ligand, poly (isobutylene-alt-maleic anhydride-graft-methoxy-poly (ethyleneglycol)-graft-imidazole-graft-Cystamine-Ce6) [PIMA-mPEG-API-SS-Ce6], and gadolinium ions (Gd³⁺). DA-SNs exhibited uniform particle size of ~48 nm, excellent stability, and inherent biosafety. Negatively charged DA-SNs could prolong blood circulation time (t_1/2 = 2.91 h) and improve tumor accumulation. Moreover, DA-SNs could undergo surface charge switch from negative charge to positive one in a slightly acidic tumor extracellular environment (pH 6.8), thus enhancing cellular uptake. After entering tumor cells, fluorescence, photodynamic therapeutic activity, and T₁MR contrast from DA-SNs could be activated within this intracellular environment with lowered pH and high level of GSH. Importantly, human tumors implanted in mice could be successfully visualized via distinct pH and redox dual-sensitive T₁MR contrast and fluorescence imaging, indicating that DA-SNs could serve as a dual-modal MR/fluorescence imaging probe for tumor-targeting diagnosis. In addition, DA-SNs exhibited superior photodynamic therapeutic efficiency with negligible side effects. Therefore, this DA-SN shows great promise for synergistic photodynamic therapy and diagnostic imaging.

Targeted drug therapy in nonsmall cell lung cancer: clinical significance and possible solutions-part II (role of nanocarriers)

INTRODUCTION

Nonsmall cell lung cancer (NSCLC) accounts for 80-85% of the cases of lung cancer. The conventional therapeutic effective dosage forms used to treat NSCLC are associated with rigid administration schedules, adverse effects, and may be associated with acquired resistance to therapy. Nanocarriers may provide a suitable alternative to regular formulations to overcome inherent drawbacks and provide better treatment modalities for the patient.

AREAS COVERED

The article explores the application of drug loaded nanocarriers for lung cancer treatment. Drug-loaded nanocarriers can be modified to achieve controlled delivery at the desired tumor infested site. The type of nanocarriers employed are diverse based on polymers, liposomes, metals and a combination of two or more different base materials (hybrids). These may be designed for systemic delivery or local delivery to the lung compartment (via inhalation).

EXPERT OPINION

Nanocarriers can improve pharmacokinetics of the drug payload by improving its delivery to the desired location and can reduce associated systemic toxicities. Through nanocarriers, a wide variety of therapeutics can be administered and targeted to the cancerous site. Some examples of the utilities of nanocarriers are codelivery of drugs, gene delivery, and delivery of other biologics. Overall, the nanocarriers have promising potential in improving therapeutic efficacy of drugs used in NSCLC.

Dual-responsive doxorubicin-loaded nanomicelles for enhanced cancer therapy

BACKGROUND

The enhancement of tumor retention and cellular uptake of drugs are important factors in maximizing anticancer therapy and minimizing side effects of encapsulated drugs. Herein, a delivery nanoplatform, armed with a pH-triggered charge-reversal capability and self-amplifiable reactive oxygen species (ROS)-induced drug release, is constructed by encapsulating doxorubicin (DOX) in pH/ROS-responsive polymeric micelle.

RESULTS

The surface charge of this system was converted from negative to positive from pH 7.4 to pH 6.8, which facilitated the cellular uptake. In addition, methionine-based system was dissociated in a ROS-rich and acidic intracellular environment, resulting in the release of DOX and α-tocopheryl succinate (TOS). Then, the exposed TOS segments further induced the generation of ROS, leading to self-amplifiable disassembly of the micelles and drug release.

CONCLUSIONS

We confirms efficient DOX delivery into cancer cells, upregulation of tumoral ROS level and induction of the apoptotic capability in vitro. The system exhibits outstanding tumor inhibition capability in vivo, indicating that dual stimuli nano-system has great potential to function as an anticancer drug delivery platform.

Nanomedicine and chemotherapeutics drug delivery: challenges and opportunities

Cancer is considered as one of the biggest threats to humans worldwide. Researchers suggest that tumour is not just a single mass, it comprises cancerous cells surrounded by noncancerous cells such as immune cells, adipocytes and cancer stem cells (CSCs) in the extracellular matrix (ECM) containing distinct components such as proteins, glycoproteins and enzymes; thus tumour microenvironment (TME) is partially complex. Multiple interactions happen in the dynamic microenvironment (ME) lead to an acidic, hypoxic and stiff ME that is considered as one of the major contributors to cancer progression and metastasis. Furthermore, TME involves in drug resistance mechanisms and affects enhanced permeability and retention (EPR) in tumours. In such a scenario, the first step to accomplish satisfying results is the identification and recognition of this ME. Then designing proper drug delivery systems can perform selectively towards cancerous cells. In this way, several targeting and stimuli/enzyme responsive drug delivery systems have been designed. More importantly, it is necessary to design a drug delivery system that can penetrate deeper into the tumours, efficiently and selectively. Various drug delivery systems such as exosomes and size-switchable nanocarriers (NCs) could decrease side effects and increase tumour treatment results by selective accumulation in tumours. In this review, TME features, current drug delivery approaches, challenges and promising strategies towards cancer treatment are discussed.

Polymer Capsules with Hydrophobic Liquid Cores as Functional Nanocarriers

Recent developments in the fabrication of core-shell polymer nanocapsules, as well as their current and future applications, are reported here. Special attention is paid to the newly introduced surfactant-free fabrication method of aqueous dispersions of nanocapsules with hydrophobic liquid cores stabilized by amphiphilic copolymers. Various approaches to the efficient stabilization of such vehicles, tailoring their cores and shells for the fabrication of multifunctional, navigable nanocarriers and/or nanoreactors useful in various fields, are discussed. The emphasis is placed on biomedical applications of polymer nanocapsules, including the delivery of poorly soluble active compounds and contrast agents, as well as their use as theranostic platforms. Other methods of fabrication of polymer-based nanocapsules are briefly presented and compared in the context of their biomedical applications.

Recent advances in improving tumor-targeted delivery of imaging nanoprobes

Tumor-targeted delivery of imaging nanoprobes provides a promising approach for the precision imaging diagnosis of cancers. Nanoprobes with desired bio-nano interface properties can preferably enter tumor tissues through the vascular endothelium, penetrate into deep tissues, and detect target lesions. Surface engineering of nanoparticles offers a critical strategy to improve tumor-targeting capacities of nanoprobes. Improvements to the efficacy of targeted nanoprobes have been intensively explored and much of this work centers on the selection of suitable targeting ligands. Herein, in this review, various recent strategies based on different targeting ligands to improve tumor-targeting of imaging nanoprobes have been developed, ranging from small molecule ligands to biomimetic coatings, with highlights on emerging coating techniques using cell membranes and dual-targeting ligands. In particular, construction and surface modification methods, targeting capacities, and imaging/theranostic performance with key issues and potential questions have been described and discussed together with considerations for future development and innovations.

Multi-transformable nanocarrier with tumor extracellular acidity-activated charge reversal, size reduction and ligand reemergence for in vitro efficient doxorubicin loading and delivery

Various nanoparticles as drug delivery system provide significant improvements in the cancer treatment. However, their clinical success remains elusive in large part due to their inability to overcome both systemic and tumor tissue barriers. The nanosystems with nanoproperty-transformability (surface, size, stability and target) hold great promise for achieving enhanced delivery efficacy. However, currently available systems that are mainly polymer-based assemblies usually suffer from the intrinsic drawbacks of poor stability, premature leakage and low drug loading as well as limited transformability. In this study, we designed a facile strategy to build a novel multi-transformable MSNs@GO nanosystem for efficient doxorubicin (DOX) loading and delivery. This novel nanosystem was well characterized and investigated in vitro. The results indicated that the MSNs@GO can realize a very high drug loading ability due to the large pore surface area of MSNs and the demonstrated donor-acceptor (boron‑nitrogen) coordination interactions between phenylboronic acid-containing nanocarriers and electron donor-containing DOX. More importantly, the novel nanocarriers can simultaneously achieve charge reversal, size reduction and ligand reemergence by shielding/deshielding transition via acid-cleavable dynamic boronate bonds under in vitro simulated acidic microenvironment of tumor tissues, opening a new avenue for improving delivery efficiency of chemotherapeutics.

Cationic Liposome/DNA Complexes Mediate Antitumor Immunotherapy by Promoting Immunogenic Tumor Cell Death and Dendritic Cell Activation

Immunotherapy has been successfully used in the treatment of multiple malignancies, but clinical studies revealed low response rates. Thus, the development of new effective immunotherapeutic modalities is urgently needed. Successfully inducing tumor cell death with enhanced antigenicity is important for the expansion and differentiation of tumor-specific CD8⁺ cytotoxic T lymphocytes. Cationic liposome/DNA complexes (CLN/DNA), which usually have obvious cytotoxic effects, may improve the antitumor immunity through enhancing the immunogenicity of dying tumor cells. Herein, we report that a plasmid DNA-encapsulated cationic lipid nanoparticle formulated with cholesterol, DOTAP, and DSPE-mPEG₂₀₀₀ significantly increases the tumor cell death with high antigenicity in vitro. Furthermore, the cationic liposome/DNA complex (CLN/DNA) treatment promotes the activation of dendritic cells (DCs). We also find that the intratumorally injected CLN/DNA successfully promoted the activation of DCs in the tumor-draining lymph node. Importantly, both local tumor growth and distant tumor formation were significantly inhibited by T cell-dependent antitumor immune responses after intratumoral injection of CLN/DNA. This study presents a simple and effective strategy for improving the cancer immunotherapy.

Overcoming the biological barriers in the tumor microenvironment for improving drug delivery and efficacy

The delivery of drugs to tumors by nanoparticles is a rapidly growing field. However, the complex tumor microenvironment (TME) barriers greatly hinder drug delivery to tumors. In this study, we first summarized the barriers in TME, including anomalous vasculature, rigid extracellular matrix, hypoxia, acidic pH, irregular enzyme level, altered metabolism pathway and immunosuppressive conditions. To overcome these barriers, many strategies have been developed, such as modulating TME, active targeting by ligand modification and biomimetic strategies, and TME-responsive drug delivery strategies to improve nanoparticle penetration, cellular uptake and drug release. Although extensive progress has been achieved, there are still many challenges, which are discussed in the last section. Overall, we carefully discuss the landscape of TME, development for improving drug delivery, and challenges that need to be further addressed.

Size and charge dual-transformable mesoporous nanoassemblies for enhanced drug delivery and tumor penetration

A series of biological barriers in a nanoparticle-formulated drug delivery process inevitably result in the current low delivery efficiency, limited tumor penetration and insufficient cellular internalization of drugs. These multiple biological barriers are intimately related to the physicochemical properties of nanoparticles, especially the contradictory demand on size and surface charge for long blood circulation (larger and negative) and deep tumor penetration (smaller) as well as efficient cellular internalization (positive). Herein, we report tumor microenvironment triggered size and charge dual-transformable nanoassemblies. The nanoassembly is realized by immobilizing positive up/downconverting luminescent nanoparticles (U/DCNPs) onto large mesoporous silica nanoparticles (MSNs) via acid-labile bonds to form core@satellite structured MSN@U/DCNPs nanoassemblies, and subsequent capping of charge reversible polymers. At physiological pH, the integrated nanoassemblies with a larger size (∼180 nm) and negative charge can effectively achieve a prolonged blood circulation and high tumor accumulation. While under an acidic tumor microenvironment, the charge reversal of outer polymers and cleavage of linkers between MSNs and U/DCNPs can induce disintegration of the nanoassemblies into isolated MSNs and smaller U/DCNPs, both with a positively charged surface, which thereby potentiate the tumor penetration and cell uptake of dissociated nanoparticles. Combined with the independent near-infrared (NIR)-to-visible and NIR-to-NIR luminescence of U/DCNPs and high surface area of MSNs, the nanoassemblies can implement NIR bioimaging guided chemo- and photodynamic combined therapy with remarkable antitumor efficiency because of the high accumulation and deep tumor penetration induced by the dual transformability of the nanoassemblies.

Size and charge dual-transformable core@satellite structured nanoassemblies are developed to overcome multiple biological barriers in a drug delivery system.

Synthesis of a biodegradable branched copolymer mPEG-b-PLGA-g-OCol and its pH-sensitive micelle

An amphiphilic biodegradable branched copolymer, mPEG-b-PLGA-g-OCol, was synthesized by grafting copolymer (methoxy polyethylene glycol)-b-Poly (l,d-lactic-co-glycolic acid) (mPEG-b-PLGA) on oligomeric collagen (OCol), to form a branched structure with mPEG-b-PLGA as side chain and OCol as backbone. mPEG-b-PLGA and mPEG-b-PLGA-g-OCol were both amphipathic and can self-assemble into micelles in aqueous solution. The mPEG-b-PLGA-g-OCol micelles showed pH-sensitive behaviors and the particle size below 100 nm in slightly acidic environment such as tumor tissue milieu interieur to perform passive targeting. Observed by SEM, when the solution pH increased from 5 to 9, the morphology of mPEG-b-PLGA-g-OCol micelles changed from small spheres to larger ones to rings. For biodegradable mPEG-b-PLGA-g-OCol, the micelles will gradually degrade in body. Further, doxorubicin (DOX) was effectively loaded in the micelles with drug loading and encapsulation efficiency of 3.48% and 25.8%, respectively. To evaluate antineoplastic effect of DOX-laden micelles in vitro, MTT test, flow cytometry and CLSM were performed and found that DOX-laden micelles exhibited higher cellular proliferation inhibition against HeLa cells. These features indicated that the mPEG-b-PLGA-g-OCol micelles were potential drug carrier for cancer therapy.

An anticancer agent-loaded PLGA nanomedicine with glutathione-response and targeted delivery for the treatment of lung cancer

Stimuli response or controlled release is a new research hotspot in nanomedicine; however, there is scarce research on organic nanomedicines with stimuli responses, which limits their practical biological applications. In addition, homoharringtonine (HHT) has been used as an effective anticancer agent, but reducing its toxicity and side effects is an urgent problem to be solved. Herein, an EGFR (epidermal growth factor receptor) aptamer-modified HHT-loaded PLGA-SS-PEG nanomedicine was developed. The nanomaterial possesses spherical morphology and admirable biocompatibility. After targeted endocytosis in tumour cells via the selective recognition between EGFR and its aptamer, the PLGA nanomedicine is triggered by a high GSH level and releases its cargo in lung cancer cells. The in vitro and in vivo results reveal that the PLGA nanomedicine not only inhibited the proliferation and promoted the apoptosis of lung cancer cells, but also possessed better therapeutic efficacy and less toxic side effects compared with the free anticancer agent. Consequently, this study provides a novel approach to construct a biodegradable nanomedicine with targeted recognition and stimuli response. Moreover, it inhibited the proliferation of lung cancer cells with high efficiency and low toxicity. Importantly, the PLGA nanomedicine demonstrates encouraging potential as a multifunctional nano-system applicable for cancer therapy.

Applications of Surface Modification Technologies in Nanomedicine for Deep Tumor Penetration

The impermeable barrier of solid tumors due to the complexity of their components limits the treatment effect of nanomedicine and hinders its clinical translation. Several methods are available to increase the penetrability of nanomedicine, yet they are too complex to be effective, operational, or practical. Surface modification employs the characteristics of direct contact between multiphase surfaces to achieve the most direct and efficient penetration of solid tumors. Furthermore, their simple operation makes their use feasible. In this review, the latest surface modification strategies for the penetration of nanomedicine into solid tumors are summarized and classified into "bulldozer strategies" and "mouse strategies." Additionally, the evaluation methods, existing problems, and the development prospects of these technologies are discussed.