A Sequential Target-Responsive Nanocarrier with Enhanced Tumor Penetration and Neighboring Effect In Vivo

Peptide nanovaccine conjugated via a retro-Diels-Alder reaction linker for overcoming the obstacle in lymph node penetration and eliciting robust cellular immunity

Nanoparticles have been regarded as a promising vaccine adjuvant due to their innate immune potentiation and enhanced antigen transport. However, the inefficient infiltration into the lymph node (LN) paracortex of nanoparticles caused by subcapsular sinus (SCS) obstruction is the main challenge in further improvement of nanovaccine immune efficacy. Herein, we propose to overcome paracortex penetration by using nanovaccine to spontaneously and continuously release antigens after retention in the SCS. In detail, we utilized a spontaneous retro-Diels-Alder (r-D-A) reaction linker to connect poly{(2-methyl-2-oxazoline)80-co-[(2-butyl-2-oxazoline)15-r-(2-thioethyl-2-oxazoline)8]} (PMBOxSH) and peptides for the peptide nanovaccine construction. The r-D-A reaction linker can spontaneously break over time, allowing the nanovaccine to release free antigens and adjuvants upon reaching the LN, thereby facilitating the entry of released antigens and adjuvants into the interior of the LNs. We showed that the efficacy of the peptide nanovaccine constructed using this dynamic linker could be significantly improved, thus greatly enhancing the tumor inhibition efficacy in the B16-OVA model. This dynamic-covalent-chemistry-based vaccine strategy may inspire designing more efficient therapeutic vaccines, especially those that require eliciting high-amount T cell responses.

Tumor Microenvironment Activatable Nanoprodrug System for In Situ Fluorescence Imaging and Therapy of Liver Cancer

The development of new imaging and treatment nanoprodrug systems is highly demanded for diagnosis and therapy of liver cancer, a severe disease characterized by a high recurrence rate. Currently, available small molecule drugs are not possible for cancer diagnosis because of the fast diffusion of imaging agents and low efficacy in treatment due to poor water solubility and significant toxic side effects. In this study, we report the development of a tumor microenvironment activatable nanoprodrug system for the diagnosis and treatment of liver cancer. This nanoprodrug system can accumulate in the tumor site and be selectively activated by an excess of hydrogen peroxide (H2O2) in the tumor microenvironment, releasing near-infrared solid-state organic fluorescent probe (HPQCY-1) and phenylboronic acid-modified camptothecin (CPT) prodrug. Both HPQCY-1 and CPT prodrugs can be further activated in tumor sites for achieving more precise in situ near-infrared (NIR) fluorescence imaging and treatment while reducing the toxic effects of drugs on normal tissues. Additionally, the incorporation of hydrophilic multivalent chitosan as a carrier effectively improved the water solubility of the system. This research thus provides a practical new approach for the diagnosis and treatment of liver cancer.

Multifunctional ZnO@DOX/ICG-LMHP Nanoparticles for Synergistic Multimodal Antitumor Activity

Multifunctional nanoparticles are of significant importance for synergistic multimodal antitumor activity. Herein, zinc oxide (ZnO) was used as pH-sensitive nanoparticles for loading the chemotherapy agent doxorubicin (DOX) and the photosensitizer agent indocyanine green (ICG), and biocompatible low-molecular-weight heparin (LMHP) was used as the gatekeepers for synergistic photothermal therapy/photodynamic therapy/chemotherapy/immunotherapy. ZnO was decomposed into cytotoxic Zn2+ ions, leading to a tumor-specific release of ICG and DOX. ZnO simultaneously produced oxygen (O2) and reactive oxygen species (ROS) for photodynamic therapy (PDT). The released ICG under laser irradiation produced ROS for PDT and raised the tumor temperature for photothermal therapy (PTT). The released DOX directly caused tumor cell death for chemotherapy. Both DOX and ICG also induced immunogenic cell death (ICD) for immunotherapy. The in vivo and in vitro results presented a superior inhibition of tumor progression, metastasis and recurrence. Therefore, this study could provide an efficient approach for designing multifunctional nanoparticles for synergistic multimodal antitumor therapy.

Photocurrent Polarity Switchable Sensing of Hyaluronidase Activity by Regulating Electrostatic Interactions between Two Semiconductors

Photocurrent polarity switchable photoelectrochemical (PEC) sensing has superior accuracy and anti-interference ability to conventional PEC sensing. The development of a novel strategy for photocurrent polarity switchable sensing is of great interest. Herein, a novel strategy for photocurrent polarity switchable sensing is reported by regulating electrostatic interactions between two semiconductor photoactive materials. Hyaluronic acid (HA)-modified CuO nanosheets show a negatively charged surface, which prevents the attachment of CuO nanosheets to negatively charged CdS nanodendrite-modified photoelectrodes because of the strong electrostatic repulsion. In the presence of hyaluronidase (HAase), the specific hydrolysis of HA on the surface of CuO by HAase can yield a positively charged surface, so CuO can be attached to a CdS-modified photoelectrode via electrostatic attraction, leading to photocurrent polarity switching. The photocurrent polarity switchable detection of HAase activity is achieved with an ultralow detection limit of 2 × 10-3 U mL-1 and a wide linear detection range between 0.01 and 100 U mL-1. This work provides a new and effective photocurrent polarity switching strategy for PEC sensing and a simple and efficient method for detecting HAase activity.

Glutathione-sensitive mesoporous nanoparticles loaded with cinnamaldehyde for chemodynamic and immunological therapy of cancer

Chemodynamic therapy as a novel type of chemotherapy can damage the DNA structures and induce cell apoptosis and immunogenic cell death (ICD) through generating reactive oxygen species (ROS) to aggravate oxidative stress. Nonetheless, as an intrinsic antioxidative response of tumor cells, the expression of glutathione (GSH) can be upregulated to maintain the cellular redox balance and protect the tumor cells from ROS-mediated damage. In this context, it is feasible to simultaneously boost ROS generation and GSH depletion in tumor cells; however, the precise delivery and release of GSH scavengers at specific subcellular sites is of great importance. Herein, we propose a GSH-responsive mesoporous organosilica nanoparticle (MON)-based nanomedicine MON-CA-TPP@HA through sequentially covalently attaching triphenylphosphine (TPP) and electrostatically coating hyaluronic acid (HA) onto the surface of cinnamaldehyde (CA)-loaded MONs, known as MON-CA-TPP@HA, which has been demonstrated to be an extremely effective therapeutic strategy for cancer treatment through inducing ICD and apoptosis of breast cancer cells. Systematic in vitro experimental results clearly revealed that the nanomedicine can actively target the tumor cells with the help of HA, subsequently enter the tumor cells, and precisely bind with the mitochondria through TPP residues. Upon cleavaging the disulfide bond in the MONs triggered by over-expressed GSH within tumors, the CA molecules can be released inducing the excessive ROS in situ surrounding the mitochondria to activate oxidative stress to induce apoptosis and ICD of breast cancer cells. The results of the in vivo experiments confirm that the MON-CA-TPP@HA nanomedicine can effectively promote dendritic cell (DC) maturation and CD 8+ T cell activation and regulate the ratio of M1/M2 macrophages, which improve tumor immunosuppressive microenvironment. It is thus believed that the current nanomedicine has paved a new way for future cancer therapy.

pH-Sensitive Biomimetic Nanosystem Based on Large-Pore Mesoporous Silica Nanoparticles with High Hyaluronidase Loading for Tumor Deep Penetration

Loading hyaluronidase (Hyal) in a nanocarrier is a potent strategy to degrade the tumor extracellular matrix for tumor deep penetration and enhanced tumor therapy. Herein, a pH-sensitive biomimicking nanosystem with high Hyal loading, effective tumor targeting, and controllable release is constructed. Specifically, cationic mesoporous silica nanoparticles (CMSNs) with large pores 13.52 nm in diameter were synthesized in a one-pot manner by adding N-[3-trimethoxysilylpropyl]-N,N,N-trimethylammonium to a reversed microemulsion reaction system. The Hyal loading rate was as high as 19.47% owing to matched pore size and the cationic surface charge. Subsequently, a pH-sensitive biomimetic hybrid membrane (pHH) composed of pH-sensitive liposome (pHL), red blood cell membrane, and pancreatic cancer cell membrane was camouflaged on the pHL-coated and doxorubicin/Hyal-loaded CMSNs (shortened as DHCM). The DHCM@pHL@pHH is stable at neutral pH while it releases the payloads smoothly in the tumor acidic microenvironment. Consequently, it can escape from macrophage clearance, be specifically taken up by pancreatic cancer cells, and efficiently accumulate at the tumor site. More importantly, it can penetrate deeply in pancreatic tumors with a tumor growth inhibition ratio of 80.46%. The nanosystem is biocompatible and has potential for clinical transformation, and the nanocarrier is promisingly applicable as a platform for encapsulation of various macromolecules for smart and tumor-targeted delivery.

Multicolor biosensor for hyaluronidase based on target-responsive hydrogel and etching of gold nanorods by H2O2

Hyaluronidase (HAase) is a potential tumor biomarker for diseases of the digestive tract and nervous system, the development of simple and sensitive techniques for HAase determination is urgent needed. Gold nanorods (Au NRs) can be etched by H₂O₂ with high efficiency and display color changing. In this work, a HAase-responsive hydrogel system had been designed and the amount of H₂O₂ spilled from the system had a close relationship with the amount of HAase, then the spilled H₂O₂ had been applied to etch Au NRs. The color change of the solution was used to realize semi-quantitative determination of HAase. Furthermore, the longitudinal peak shift of Au NRs had a linear correlation with the concentration of HAase in the range of 10-60 U/mL (within 40 min) and the limit of detection (LOD) was 3.8 U/mL (S/N = 3), which can be used to realize accurate quantitative analysis of HAase. The proposed method has been applied to monitor HAase in serum of pancreatic cancer patients with satisfied results.

Design of Disintegrable Nanoassemblies to Release Multiple Small-Sized Nanoparticles

The therapeutic and diagnostic effects of nanoparticles depend on the efficiency of their delivery to targeted tissues, such as tumors. The size of nanoparticles, among other characteristics, plays a crucial role in determining their tissue penetration and retention. Small nanoparticles may penetrate deeper into tumor parenchyma but are poorly retained, whereas large ones are distributed around tumor blood vessels. Thus, compared to smaller individual nanoparticles, assemblies of such nanoparticles due to their larger size are favorable for prolonged blood circulation and enhanced tumor accumulation. Upon reaching the targeted tissues, nanoassemblies may dissociate at the target region and release the smaller nanoparticles, which is beneficial for their distribution at the target site and ultimate clearance. The recent emerging strategy that combines small nanoparticles into larger, biodegradable nanoassemblies has been demonstrated by several groups. This review summarizes a variety of chemical and structural designs for constructing stimuli-responsive disintegrable nanoassemblies as well as their different disassembly routes. These nanoassemblies have been applied as demonstrators in the fields of cancer therapy, antibacterial infection, ischemic stroke recovery, bioimaging, and diagnostics. Finally, we summarize stimuli-responsive mechanisms and their corresponding nanomedicine designing strategies, and discuss potential challenges and barriers towards clinical translation.

A Motor-Based Carbonaceous Nanocalabash Catalyst for Deep-Layered Bioorthogonal Chemistry

Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has been widely regarded as a promising avenue in bioorthogonal chemistry. The emerging heterogeneous copper catalysts have been developed with a series of exciting applications such as in situ activation of prodrugs because of their excellent stability and biocompatibility. However, due largely to the complex biophysical barriers in living organisms, most synthetic bioorthogonal drugs cannot penetrate deep pathological tissues. Especially in biofilm-associated infections, the biofilms severely block the penetration of traditional antimicrobial agents and increase the antibiotic resistance, which makes it extremely difficult to eliminate the biofilms. Inspired by self-propelled biological motors, such as enzymes, herein, we develop a NIR light-controllable carbonaceous nanocalabash (CNC) motor catalyst with good biocompatibility for active targeted synthesis of drugs inside the biofilms as a robust general-purpose bioorthogonal platform. Under the NIR laser, the CNC motor catalysts display a rapid autonomous motion and generate active molecules in the deep biofilm layers, removing the biofilms and eradicating the shielded bacteria. Our work will shed light on developing a robust bioorthogonal platform for active targeted synthesis of drugs in deep-layered living systems.

A Two-Pronged Strategy for Enhanced Deep-Tumor Penetration and NIR-II Multimodal Imaging-Monitored Photothermal Therapy

The second near-infrared (NIR-II)-induced photothermal therapy (PTT) has attracted a great deal of attention in recent years due to its non-invasiveness and because it uses less energy. However, the penetration of photothermal agents into solid tumors is seriously impeded by the dense-tumor extracellular matrix (ECM) containing cross-linked hyaluronic acid (HA), thereby compromising the ultimate therapeutic effects. Herein, acid-labile metal-organic frameworks were employed as nanocarriers to efficiently mineralize hyaluronidase (HAase) and encapsulate Ag₂S nanodots by a one-pot approach under mild conditions. The obtained nanocomposites (AHZ NPs) maintained enzyme activity and changed in size to prolong blood circulation and complete delivery of the cargo to the tumor. Moreover, the released HAase could specifically break out the HA to loosen ECM and enable the Ag₂S nanodots to breeze through the tumor matrix space and gain access to the deep tumor. Under near-infrared laser irradiation, the AHZ NPs displayed remarkable fluorescence, outstanding photoacoustic signals, and excellent photothermal properties in the whole tumor. This work offers a promising two-pronged strategy via a decrease in nanoparticle size and the degradation of dense ECM for NIR-II multimodal imaging-guided PTT of deep tumors.

A porphyrin-based metallacage for enhanced photodynamic therapy

In this study, we designed an effective nanoplatform to improve the photodynamic therapy (PDT) of porphyrins. Combining a porphyrin-based metallacage (PM), hyaluronidase (HAase) and DSPE-mPEG2000 together, the nanoparticle (PM@HAase-mPEG) showed enhanced PDT efficacy. The PM improved the stability of the porphyrin, avoided its aggregation and provided cavities to concentrate oxygen molecules, which was beneficial for enhancing PDT. HAase degraded HA to increase the intracellular accumulation of nanoparticles, normalized blood vessels and relieved hypoxia in tumors. PM@HAase-mPEG inhibited the growth of tumors in a 4T1 mouse model by the generated singlet oxygen with excellent PDT efficacy. This study resolved the problems of the instability of PSs, less cellular accumulation of drugs, and tumor hypoxia that limited the anti-tumor application of PDT.

pH-Sensitive and Charge-Reversal Polymeric Nanoplatform Enhanced Photothermal/Photodynamic Synergistic Therapy for Breast Cancer

As reported, breast cancer is one of the most common malignancies in women and has overtaken lung cancer as the most commonly diagnosed cancer worldwide by 2020. Currently, phototherapy is a promising anti-tumor therapy due to its fewer side effects, less invasiveness, and lower cost. However, its application in cancer therapeutics is limited by the incomplete therapeutic effect caused by low drug penetration and monotherapy. Herein, we built a charge-reversal nanoplatform (Ce6-PLGA@PDA-PAH-DMMA NPs), including polydopamine (PDA) and chlorin e6 (Ce6) for enhancing photothermal/photodynamic synergistic therapy. The PAH-DMMA charge-reversal layer enabled Ce6-PLGA@PDA-PAH-DMMA NPs to have long blood circulation at the normal physiological environment and to successfully realize charge reversal under the weakly acidic tumor microenvironment, improving cellular uptake. Besides, in vitro tests demonstrated that Ce6-PLGA@PDA-PAH-DMMA NPs had high photothermal conversion and greater anti-tumor activity than no charge-reversal nanoparticles, which overcame the limited tumor therapeutic efficacy of PTT or photodynamic therapy alone. Overall, the design of pH-responsive and charge-reversal nanoparticles (Ce6-PLGA@PDA-PAH-DMMA NPs) provided a promising approach for synergistic PTT/PDT therapy against breast cancer.

Precise Anti-Tumor Effect of a Metallopolysaccharide-Based Nanotheranostic: Turning Phototherapy into Programmed Chemotherapy

Phototheranostic, a regional-focused treatment, can endow cancer theranostic with low damage due to its spatial precision. However, precise elimination of residual cancer cells in laser-focused field and in non-laser-focused field...

Tumor targeting and penetrating biomimetic mesoporous polydopamine nanoparticles facilitate photothermal killing and autophagy blocking for synergistic tumor ablation

The synergistic manipulation of autophagy blocking with tumor targeting and penetration effects to enhance cancer cell killing during photothermal therapy (PTT) remains a substantial challenge. Herein, we fabricated a biomimetic nanoplatform by precisely coating homologous prostate cancer cell membranes (CMs) onto the surface of mesoporous polydopamine nanoparticles (mPDA NPs) encapsulating the autophagy inhibitor chloroquine (CQ) for synergistically manipulating PTT and autophagy for anticancer treatment. The resulting biomimetic mPDA@CMs NPs-CQ system could escape macrophage phagocytosis, overcome the vascular barrier, and home in the homologous prostate tumor xenograft with high tumor targeting and penetrating efficiency. The mPDA NPs core endowed the mPDA@CMs NPs-CQ with good photothermal capability to mediate PTT killing of prostate cancer cells, while NIR-triggered CQ release from the nanosystem further arrested PTT-induced protective autophagy of cancer cells, thus weakening the resistance of prostate cancer cells to PTT. This combined PTT killing and autophagy blocking anticancer strategy could induce significant autophagosome accumulation, ROS generation, mitochondrial damage, endoplasmic reticulum stress, and apoptotic signal transduction, which finally results in synergistic prostate tumor ablation in vivo. This prostate cancer biomimetic nanosystem with synergistically enhanced anticancer efficiency achieved by manipulating PTT killing and autophagy blocking is expected to serve as a more effective anticancer strategy against prostate cancer. STATEMENT OF SIGNIFICANCE: Autophagy is considered as one of the most efficient rescuer and reinforcement mechanisms of cancer cells against photothermal therapy (PTT)-induced cancer cell eradication. How to synergistically manipulate autophagy blocking with significant tumor targeting and penetration to enhance PTT-mediated cancer cell killing remains a substantial challenge. Herein, we fabricated a biomimetic nanoplatform by precisely coating homologous cancer cell membranes onto the surface of mesoporous polydopamine nanoparticles with encapsulation of the autophagy inhibitor chloroquine for synergistic antitumor treatment with high tumor targeting and penetrating efficiency both in vitro and in vivo. This biomimetic nanosystem with synergistically enhanced anticancer efficiency by manipulating PTT killing and autophagy blocking is expected to serve as a more effective anticancer strategy.

A smart O2-generating nanocarrier optimizes drug transportation comprehensively for chemotherapy improving

Drug transportation is impeded by various barriers in the hypoxic solid tumor, resulting in compromised anticancer efficacy. Herein, a solid lipid monostearin (MS)-coated CaO₂/MnO₂ nanocarrier was designed to optimize doxorubicin (DOX) transportation comprehensively for chemotherapy enhancement. The MS shell of nanoparticles could be destroyed selectively by highly-expressed lipase within cancer cells, exposing water-sensitive cores to release DOX and produce O₂. After the cancer cell death, the core-exposed nanoparticles could be further liberated and continue to react with water in the tumor extracellular matrix (ECM) and thoroughly release O₂ and DOX, which exhibited cytotoxicity to neighboring cells. Small DOX molecules could readily diffuse through ECM, in which the collagen deposition was decreased by O₂-mediated hypoxia-inducible factor-1 inhibition, leading to synergistically improved drug penetration. Concurrently, DOX-efflux-associated P-glycoprotein was also inhibited by O₂, prolonging drug retention in cancer cells. Overall, the DOX transporting processes from nanoparticles to deep tumor cells including drug release, penetration, and retention were optimized comprehensively, which significantly boosted antitumor benefits.

Tumor-Specific ONOO- Nanogenerator for Improved Drug Delivery and Enhanced Chemotherapy of Tumor

Multiple biological barriers in solid tumors severely restrict the penetration of nanomedicines, which is a main cause for therapeutic failure in traditional tumor treatment. Here, a tumor-specific nanogenerator of peroxynitrite (ONOO^-), prepared by loading cisplatin and sodium nitroprusside into poly(d,l-lactide-co-glycolide) polymersomes, was designed to improve drug delivery and enhance tumor chemotherapy. After a cascade of nicotinamide adenine dinucleotide phosphate oxidases catalysis and glutathione reduction, the nanogenerator, namely, PMCS, could selectively induce the generation of ONOO^- in tumor. The generated ONOO^- could not only strengthen vascular permeability significantly but also improve the accumulation and penetration of PMCS in tumor by activating matrix metalloproteinases-mediated degradation of extracellular matrix. Along with endocytosis, PMCS released cisplatin to induce tumor cell apoptosis. Moreover, free cisplatin liberated from dead cells infected neighboring tumor cells quickly via ONOO^--mediated up-regulated copper transporter 1, further amplifying chemotherapeutic efficacy. This study advances ONOO^- as a potent modality to address the main issues of therapeutic delivery, including but not limited to chemotherapy.

Tumor microenvironment remodeling-based penetration strategies to amplify nanodrug accessibility to tumor parenchyma

Remarkable advances in nano delivery systems have provided new hope for tumor prevention, diagnosis and treatment. However, only limited clinical therapeutic effects against solid tumors were achieved. One of the main reasons is the presence of abundant physiological and pathological barriers in vivo that impair tumoral penetration and distribution of the nanodrugs. These barriers are related to the components of tumor microenvironment (TME) including abnormal tumor vasculature, rich composition of the extracellular matrix (ECM), and abundant stroma cells. Herein, we review the advanced strategies of TME remodeling to overcome these biological obstacles against nanodrug delivery. This review aims to offer a perspective guideline for the implementation of promising approaches to facilitate intratumoral permeation of nanodrugs through alleviation of biological barriers. At the same time, we analyze the advantages and disadvantages of the corresponding methods and put forward possible directions for the future researches.

Icebreaker-inspired Janus nanomotors to combat barriers in the delivery of chemotherapeutic agents

Cancer chemotherapy remains challenging to pass through various biological and pathological barriers such as blood circulation, tumor infiltration and cellular uptake before the intracellular release of antineoplastic agents. Herein, icebreaker-inspired Janus nanomotors (JMs) are developed to address these transportation barriers. Janus nanorods (JRs) are constructed via seed-defined growth of mesoporous silica nanoparticles on doxorubicin (DOX)-loaded hydroxyapatite (HAp) nanorods. One side of JRs is grafted with urease as the motion power via catalysis of physiologically existed urea, and hyaluronidase (HAase) is on the other side to digest the viscous extracellular matrices (ECM) of tumor tissues. The rod-like feature of JMs prolongs the blood circulation, and the self-propelling force and instantaneous digestion of hyaluronic acid along the moving paths promote extravasation across blood vessels and penetration in tumor mass, leading to 2-fold higher drug levels in tumors after JM administration than those with JRs. The digestion of ECM in the diffusion paths is more effective to enhance drug retention and diffusion in tumors compared with enzyme-mediated motion. The ECM digestion and motion capabilities of JMs show no influence on the endocytosis mechanism, but lead to over 3-fold higher cellular uptake than those of pristine JRs. The JM treatment promotes therapeutic efficacy in terms of survival prolongation, tumor growth inhibition and cell apoptosis induction and causes no tumor metastasis to lungs with normal alveolar spaces. Thus, the self-driven motion and instantaneous clearance of diffusion routes demonstrate a feasible strategy to combat a series of biological barriers in the delivery of chemotherapeutic agents in favor of antitumor efficacy.

Dual-Responsive and Deep-Penetrating Nanomicelles for Tumor Therapy via Extracellular Matrix Degradation and Oxidative Stress

Tumor microenvironment (TME), with complex composition, plays a vital role in the occurrence, development, and metastasis of tumors. TME becomes an important obstacle to the accessibility of nanotherapy, thus indicating the need to improve the functional design to overcome this challenge. In this study, we generate an intelligent nano-drug-delivery system (DOX@PssP-Hh NPs) with dual environmental response, which involves heparanase (HPSE) in TME and glutathione (GSH) in tumor cells. The nanosystem consists of a nanoskeleton formed by self-assembly of mPEG-ss-PEI and α-CD (PssP), chemotherapy drug doxorubicin (DOX) for enhancing antitumor efficacy, together with hyaluronidase (HAase), which is designed to degrade extracellular matrix to increase drug penetration, and an outer shell of heparin. Through the process of "responsive disintegration-remodeling tumor microenvironment-enhancing drug penetration-inducing oxidative stress", the semi-rotaxaneself-assembled nanomicelles were constructed to achieve the progressive function. DOX@PssP-Hh NPs with the size of 81.85 ± 1.85 nm exhibited satisfactory cytotoxicity (IC₅₀ = 0.80 ± 0.33 μg/mL). With the disulfide bond-mediated GSH depletion and DOX-mediated reactive oxygen species (ROS) production, treatment with DOX@PssP-Hh NPs prominently reduced glutathione peroxidase 4 (GPX4) level and would lead to enhanced oxidative stresses. Hyaluronic acid (HA), collagen I, and α-smooth muscle actin (α-SMA) were significantly reduced for TME remodulation. Moreover, the antitumor effect in vivo implied that DOX@PssP-Hh NPs could inhibit tumor growth effectively and reduce tumor interstitial fluid pressure (IFP) evidently. In conclusion, DOX@PssP-Hh NPs improved the penetration of drugs and exhibited enhanced antitumor efficacy.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

An Activatable Nano-Prodrug for Treating Tyrosine-Kinase-Inhibitor-Resistant Non-Small Cell Lung Cancer and for Optoacoustic and Fluorescent Imaging

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer and the cause of high rate of mortality. The epidermal growth factor receptor (EGFR)-targeted tyrosine kinase inhibitors are used to treat NSCLC, yet their curative effects are usually compromised by drug resistance. This study demonstrates a nanodrug for treating tyrosine-kinase-inhibitor-resistant NSCLC through inhibiting upstream and downstream EGFR signaling pathways. The main molecule of the nanodrug is synthesized by linking a tyrosine kinase inhibitor gefitinib and a near-infrared dye (NIR) on each side of a disulfide via carbonate bonds, and the nanodrug is then obtained through nanoparticle formation of the main molecule in aqueous medium and concomitant encapsulation of a serine threonine protein kinase (Akt) inhibitor celastrol. Upon administration, the nanodrug accumulates at the tumor region of NSCLC-bearing mice and releases the drugs for tumor inhibition, and the dye for fluorescence and optoacoustic imaging. Through suppressing the phosphorylation of upstream EGFR and downstream Akt in the EGFR pathway by gefitinib and celastrol, respectively, the nanodrug exhibits high inhibition efficacy against orthotopic NSCLC in mouse models.

Enhancement of tumour penetration by nanomedicines through strategies based on transport processes and barriers

Nanomedicines for antitumour therapy have been widely studied in recent decades, but only a few have been used in clinical applications. One of the most important reasons is the poor tumour permeability of the nanomedicines. In this three-part review, intravascular, transvascular and extravascular transport were introduced one by one according to their roles in the overall process of nanomedicine transport into tumours. Transportation obstacles, such as elevated interstitial fluid pressure (IFP), abnormal blood vessels, dense tumour extracellular matrix (ECM) and binding site barriers (BSB), were each discussed in the context of the respective transport processes. Furthermore, homologous resolution strategies were summarized on the basis of each transportation obstacle, such as the normalization of blood vessels, regulation of the tumour microenvironment (TME) and application of transformable nanoparticles. At the end of this review, we propose holistic, concrete, and innovative views for better tumour penetration of nanomedicines.

Mechanism Investigation of Hyaluronidase-Combined Multistage Nanoparticles for Solid Tumor Penetration and Antitumor Effect

Background

Hyaluronic acid (HA) is a major component of extracellular matrix (ECM) and its over expression in tumor tissues contributes to the increase of interstitial fluid pressure (IFP) and hinders the penetration of nanoparticles into solid tumors.

Materials and Methods

We here reported a tumoral microenvironment responsive multistage drug delivery system (NPs-EPI/HAase) which was formed layer by layer via electrostatic interaction with epirubicin (EPI)-loaded PEG-b-poly(2-(diisopropylamino)ethyl methacrylate)-b-poly(2-guanidinoethylmethacrylate) (mPEG-PDPA-PG, PEDG) micelles (NPs-EPI) and hyaluronidase (HAase). In this paper, we focused on the hyaluronidase-combined nanoparticles (NPs-EPI/HAase) for tumor penetration in tumor spheroid and solid tumor models in vitro and in vivo.

Results

Our results showed that NPs-EPI/HAase effectively degrade the HA in ECM and facilitate deep penetration of NPs-EPI into solid tumor. Moreover, NPs-EPI mainly employed clathrin-mediated and macropinocytosis-mediated endocytic pathways for cellular uptake and were subsequently directed to the lysosomes for further drug release triggered by proton sponge effect. Compared with NPs-EPI, the HAase coating group showed an enhanced tumoral drug delivery efficacy and inhibition of tumor growth.

Conclusion

Overall, our studies demonstrated that coating nanoparticles with HAase can provide a simple but efficient strategy for nano-drug carriers to enhance solid tumor penetration and chemotherapeutic efficacy.

Reduction/Oxidation-Responsive Hierarchical Nanoparticles with Self-Driven Degradability for Enhanced Tumor Penetration and Precise Chemotherapy

Deep tumor penetration, long blood circulation, rapid drug release, and sufficient stability are the most concerning dilemmas of nano-drug-delivery systems for efficient chemotherapy. Herein, we develop reduction/oxidation-responsive hierarchical nanoparticles co-encapsulating paclitaxel (PTX) and pH-stimulated hyaluronidase (pSH) to surmount the sequential biological barriers for precise cancer therapy. Poly(ethylene glycol) diamine (PEG-dia) is applied to collaboratively cross-link the shell of nanoparticles self-assembled by a hyaluronic acid-stearic acid conjugate linked via a disulfide bond (HA-SS-SA, HSS) to fabricate the hierarchical nanoparticles (PHSS). The PTX and pSH coloaded hierarchical nanoparticles (PTX/pSH-PHSS) enhance the stability in normal physiological conditions and accelerate drug release at tumorous pH, and highly reductive or oxidative environments. Functionalized with PEG and HA, the hierarchical nanoparticles preferentially prolong the circulation time, accumulate at the tumor site, and enter MDA-MB-231 cells via CD44-mediated endocytosis. Within the acidic tumor micro-environment, pSH would be partially reactivated to decompose the dense tumor extracellular matrix for deep tumor penetration. Interestingly, PTX/pSH-PHSS could be degraded apace by the completely activated pSH within endo/lysosomes and the intracellular redox micro-environment to facilitate drug release to produce the highest tumor inhibition (93.71%) in breast cancer models.

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance.