Doxorubicin‐Conjugated Immuno‐Nanoparticles for Intracellular Anticancer Drug Delivery

A polymeric nanoparticle comprised of surface furan groups is used to bind, by Diels–Alder (DA) coupling chemistry, both targeting anti‐human epidermal growth factor receptor 2 (anti‐HER2) antibodies and chemotherapeutic doxorubicin (DOX) for targeted, intracellular delivery of DOX. In this new approach for delivery, where both chemotherapeutic and targeting ligand are attached, for the first time, to the surface of the delivery vehicle, the nuclear localization of DOX in HER2‐overexpressing breast cancer SKBR‐3 cells is demonstrated, as determined by confocal laser scanning microscopy. Flow cytometric analysis shows that the conjugated DOX maintains its biological function and induces similar apoptotic progression in SKBR‐3 cells as free DOX. The viable cell counts of SKBR‐3 cancer cells following incubation with different nanoparticle formulations demonstrates that the combined DOX and anti‐HER2 nanoparticle is more efficacious than the nanoparticle formulation with either DOX or anti‐HER2 alone. While free DOX shows similar cytotoxicity against both cancerous SKBR‐3 cells and healthy HMEC‐1 cells, the combined DOX‐anti‐HER2 nanoparticle is significantly more cytotoxic against SKBR‐3 cells than HMEC‐1 cells, suggesting the benefit of nanoparticle‐conjugated DOX for cell type‐specific targeting. The DOX‐conjugated immuno‐nanoparticle represents an entirely new method for localized co‐delivery of chemotherapeutics and antibodies.     

Tumor‐Microenvironment‐Adaptive Nanoparticles Codeliver Paclitaxel and siRNA to Inhibit Growth and Lung Metastasis of Breast Cancer

Prolonged circulation, specific and effective uptake by tumor cells, and rapid intracellular drug release are three main factors for the drug delivery systems to win the battle against metastatic breast cancer. In this work, a tumor microenvironment‐adaptive nanoparticle co‐loading paclitaxel (PTX) and the anti‐metastasis siRNA targeting Twist is prepared. The nanoparticle consists of a pH‐sensitive core, a cationic shell, and a matrix metalloproteinase (MMP)‐cleavable polyethylene glycol (PEG) corona conjugated via a peptide linker. PEG will be cut away by MMPs at the tumor site, which endows the nanoparticle with smaller particle size and higher positive charge, leading to more efficient cellular uptake in tumor cells and higher intra‐tumor accumulation of both PTX and siRNA in the 4T1 tumor‐bearing mice models compared to the nanoparticles with irremovable PEG. In addition, acid‐triggered drug release in endo/lysosomes is achieved through the pH‐sensitive core. As a result, the MMP/pH dual‐sensitive nanoparticles significantly inhibit tumor growth and pulmonary metastasis. Therefore, this tumor‐microenvironment‐adaptive nanoparticle can be a promising codelivery vector for effective therapy of metastatic breast cancer due to simultaneously satisfying the requirements of long circulating time, efficient tumor cell targeting, and fast intracellular drug release.     

Two‐Step Targeted Hybrid Nanoconstructs Increase Brain Penetration and Efficacy of the Therapeutic Antibody Trastuzumab against Brain Metastasis of HER2‐Positive Breast Cancer

Therapeutic antibodies (e.g., trastuzumab, TRA) against human epidermal growth factor receptor 2 (HER2)‐positive breast cancers have shown benefits in controlling primary tumors, yet are ineffective against brain metastases due to their inability to cross the blood‐brain barrier (BBB). A novel hybrid nanoconstruct system is designed to deliver trastuzumab to brain metastasis of HER2‐positive breast cancer via a two‐step sequential targeting approach. Self‐assembly of a polysorbate 80 (PS 80)‐containing polymer, lipid, and polymer‐conjugated TRA forms hybrid nanoconstructs (TRA–terpolymer nanoparticles (TPN)) with high encapsulation efficiency and bioactivity. The PS 80 moiety enables the first‐step targeting and receptor‐mediated trancytosis across BBB is demonstrated in vitro with a 3D human BBB model in healthy and brain tumor‐bearing mice. The subsequent partial dissociation of the nanoconstructs exposes the encapsulated TRA for the second‐step targeting to HER2‐positive cancer cells in the brain. Intravenously injected TRA–TPN delivers 50‐fold TRA compared to free TRA to the brain metastasis of HER2‐positive breast cancer. Treatment with TRA–TPN increases tumor cell apoptosis by 4‐fold, inhibits tumor growth by 43‐fold, and prolongs median survival by >1.3‐fold compared to free TRA, without causing noticeable organ toxicity. These findings suggest the two‐step targeted nanoconstruct system is promising for shuttling therapeutic antibodies to treat central nervous system diseases.     

Binary Targeting of siRNA to Hematologic Cancer Cells In Vivo Using Layer‐by‐Layer Nanoparticles

Using siRNA therapeutics to treat hematologic malignancies has been unsuccessful because blood cancer cells exhibit remarkable resistance to standard transfection methods. Herein, the successful delivery of siRNA therapeutics with a dual‐targeted, layer‐by‐layer nanoparticle (LbL‐NP) is reported. The LbL‐NP protects siRNA from nucleases in the bloodstream by embedding it within polyelectrolyte layers that coat a polymeric core. The outermost layer consists of hyaluronic acid (a CD44‐ligand) covalently conjugated to CD20 antibodies. The CD20/CD44 dual‐targeting outer layer provides precise binding to blood cancer cells, followed by receptor‐mediated endocytosis of the LbL‐NP. This siRNA delivery platform is used to silence B‐cell lymphoma 2 (BCL‐2), a pro‐survival protein, in vitro and in vivo. The dual‐targeting approach significantly enhances internalization of BCL‐2 siRNA in lymphoma and leukemia cells, which leads to significant downregulation of BCL‐2 expression. Systemic administration of the dual‐targeted, siRNA‐loaded nanoparticle induces apoptosis and hampers proliferation of blood cancer cells, both in cell culture and in orthotopic non‐Hodgkin's lymphoma animal models. These results provide the basis for approaches to targeting blood‐borne cancers and other diseases and suggest that LbL nanoassemblies are a promising approach for delivering therapeutic siRNA to hematopoetic cell types that are known to evade transfection by other means.     

MAPK‐Targeted Drug Delivered by a pH‐Sensitive MSNP Nanocarrier Synergizes with PD‐1 Blockade in Melanoma without T‐Cell Suppression

The combination of BRAF/MEK‐targeted therapy with immune checkpoint blockade is regarded as a promising regimen for patients with metastatic melanoma due to their complementary advantages. However, MEK‐inhibitor‐induced T‐cell toxicity impedes effective cooperation. In this experiment, a pH‐responsive on‐demand controlled release mesoporous silica nanoparticles (MSNPs) system is designed. Fluorescein‐isothiocyanate‐loaded MSNP can be specifically delivered into tumor cells rather than T‐cells. MEK‐inhibitor‐loaded MSNP avoids proliferative and functional inhibitions of T‐cells, while preserving growth suppression of tumor cells in vitro. In an in vivo model, MSNP encapsulation reverses the MEK‐inhibitor‐induced suppression of activated CD8⁺ T‐cells, and enhances the secretion of INF‐γ and IL‐2. The combination of BRAF inhibitor plus MSNP‐loaded MEK inhibitor and anti‐PD‐1 antibody synergistically inhibits tumor growth via promoting robust immune‐related antitumor response. This work provides a novel and generalized framework for combining T‐cell‐impaired targeted therapy and immune checkpoint blockade by using a nanoparticle‐based delivery system.     

A Multi‐Gradient Targeting Drug Delivery System Based on RGD‐l‐TRAIL‐Labeled Magnetic Microbubbles for Cancer Theranostics

The accurately and efficiently targeted delivery of therapeutic/diagnostic agents into tumor areas in a controllable fashion remains a big challenge. Here, a novel cancer targeting magnetic microbubble is elaborately fabricated. First, the γ‐Fe₂O₃ magnetic iron oxide nanoparticles are optimized to chemically conjugate on the surface of polymer microbubbles. Then, arginine‐glycine‐aspartic acid‐l ‐tumor necrosis factor‐related apoptosis‐inducing ligand (RGD‐l ‐TRAIL), antitumor targeting fusion protein, is precisely conjugated with magnetic nanoparticles of microbubbles to construct RGD molecularly targeted magnetic microbubble, which is defined as RGD‐l ‐TRAIL@MMBs. Such RGD‐l ‐TRAIL@MMBs is endowed with the multigradient cascade targeting ability following by magnetic targeting, RGD, as well as enhanced permeability and retention effect regulated targeting to result in high cancerous tissue targeting efficiency. Due to the highly specific accumulation of RGD‐l ‐TRAIL@MMBs in the tumor, the accurate diagnostic information of tumor can be obtained by dual ultrasound and magnetic resonance imaging. After imaging, the TRAIL molecules as anticancer agent also get right into the cancer cells by nanoparticle‐ and RGD‐mediated endocytosis to effectively induce the tumor cell apoptosis. Therefore, RGD‐l ‐TRAIL conjugated magnetic microbubbles could be developed as a molecularly targeted multimodality imaging delivery system with the addition of chemotherapeutic cargoes to improve cancer diagnosis and therapy.     

Transformable Nanoparticle‐Enabled Synergistic Elicitation and Promotion of Immunogenic Cell Death for Triple‐Negative Breast Cancer Immunotherapy

Although cisplatin‐based neoadjuvant chemotherapy is an efficient therapy approach for triple‐negative breast cancer (TNBC), it has dismal prognosis and modestly improved survival benefit. Here, a synergistic immunotherapy of TNBC premised on the elicitation and promotion of immunogenic cell death (ICD) response, through a transformable nanoparticle‐enabled approach for contemporaneous delivery of cisplatin, adjudin, and WKYMVm is reported. The nanoparticles can sequentially respond to matrix metalloproteinases‐2, pH, and glutathione to achieve structural transformation with the advantages of optimal size change, efficient drug delivery, and well‐controlled release. Cisplatin and adjudin can synergistically amplify reactive oxygen species (ROS) cascade and eventually increase the formation of hydrogen peroxide and downstream highly toxic ROS like ?OH, which can elicit ICD response by mechanisms of endoplasmic reticulum stress, apoptotic cell death, and autophagy. WKYMVm can further promote anti‐TNBC immunity by activation of formyl peptide receptor 1 to build stable interactions between dendritic cells and dying cancer cells. Thus, the nanoparticles achieve significant primary tumor regression and pulmonary metastasis inhibition as well as a remarkable survival benefit, with boosting of the innate and adaptive anti‐TNBC immunity.     

Polyhedral Oligomeric Silsesquioxanes‐Containing Conjugated Polymer Loaded PLGA Nanoparticles with Trastuzumab (Herceptin) Functionalization for HER2‐Positive Cancer Cell Detection

The synthesis of polyhedral oligomeric silsesquioxanes (POSS)‐containing conjugated polymer (CP) and the polymer loaded poly(lactic‐co‐glycolic‐acid) (PLGA) nanoparticles (NPs) with surface antibody functionalization for human epidermal growth factor receptor 2 (HER2)‐positive cancer cell detection are reported. Due to the steric hindrance of POSS, NPs prepared from POSS‐containing CP show improved photoluminescence quantum yield as compared to that for the corresponding linear CP encapsulated NPs. In addition, the amount of ‐NH₂ groups on NP surface is well‐controlled by changing the molar ratio of poly(lactic‐co‐glycolic‐acid)‐b‐poly(ethylene glycol) (PLGA‐b‐PEG‐NH₂) to PLGA‐OCH₃ during NP formulation. Further conjugation of the NH₂‐functionalized CP NPs with trastuzumab (Herceptin) yields NPs with fine‐tuned protein density. These NPs are able to discriminate SKBR‐3 breast cancer cells from MCF‐7 breast cancer cells and NIH/3T3 fibroblast cells both on substrate and in suspension by taking advantage of the specific binding affinity between trastuzumab and HER2 overexpressed in SKBR‐3 breast cancer cell membrane. The high quantum yield and fine‐tuned surface specific protein functionalization make the POSS‐containing CP loaded NPs a good candidate for targeted biological imaging and detection.     

Cancer Detection: Polyhedral Oligomeric Silsesquioxanes‐Containing Conjugated Polymer Loaded PLGA Nanoparticles with Trastuzumab (Herceptin) Functionalization for HER2‐Positive Cancer Cell Detection (Adv. Funct. Mater. 2/2011)

The synthesis of polyhedral oligomeric silsesquioxanes (POSS)‐containing conjugated polymer (CP) and the polymer loaded poly(lactic‐co‐glycolic‐acid) (PLGA) nanoparticles (NPs) with surface antibody functionalization for human epidermal growth factor receptor 2 (HER2)‐positive cancer cell detection are reported. Due to the steric hindrance of POSS, NPs prepared from POSS‐containing CP show improved photoluminescence quantum yield as compared to that for the corresponding linear CP encapsulated NPs. In addition, the amount of ‐NH₂ groups on NP surface is well‐controlled by changing the molar ratio of poly(lactic‐co‐glycolic‐acid)‐b‐poly(ethylene glycol) (PLGA‐b‐PEG‐NH₂) to PLGA‐OCH₃ during NP formulation. Further conjugation of the NH₂‐functionalized CP NPs with trastuzumab (Herceptin) yields NPs with fine‐tuned protein density. These NPs are able to discriminate SKBR‐3 breast cancer cells from MCF‐7 breast cancer cells and NIH/3T3 fibroblast cells both on substrate and in suspension by taking advantage of the specific binding affinity between trastuzumab and HER2 overexpressed in SKBR‐3 breast cancer cell membrane. The high quantum yield and fine‐tuned surface specific protein functionalization make the POSS‐containing CP loaded NPs a good candidate for targeted biological imaging and detection.     

iRGD Modified Chemo‐immunotherapeutic Nanoparticles for Enhanced Immunotherapy against Glioblastoma

Glioblastoma is the most common primary brain tumor in adults and still remains incurable, due to the limited accumulation of drugs in the tumor area. Herein, iRGD‐modified nanoparticles, DOX@MSN‐SS‐iRGD&1MT, are developed for simultaneous delivery of chemotherapeutic agents (doxorubicin, DOX) and immune checkpoint inhibitor (1‐methyltryptophan, 1MT) into orthotopic glioma. The nanoparticles are comprised of mesoporous silica nanoparticles loaded with DOX, combined with Asp‐Glu‐Val‐Asp (DEVD) connected 1MT, and finally modified by iRGD. These nanoparticles show the capability of penetrating through blood brain barrier into the tumor area, and significantly improve accumulation of drugs in orthotopic brain tumors with minimal side effects. The nanoparticles also activate cytotoxic CD8⁺ T lymphocytes and inhibit CD4⁺ T cells in both GL261 cells cocultured with splenocytes in vitro and GL261‐luc orthotopic tumors in vivo. Moreover, the expression of antitumor cytokines IFNα/β, IFN‐γ, TNF, IL‐17, STING, and GrzB is upregulated while protumor proteins p‐STAT3 and IL‐10 are downregulated in the brain tumor area. This study demonstrates the advantages of chemo‐immunotherapeutic nanoparticles accumulated in the brain tumor area and their effectively inhibiting tumor proliferation, which establishes a delivery platform to promote antitumor immunity against glioblastoma.     

A Fabricated siRNA Nanoparticle for Ultralong Gene Silencing In Vivo

Persistent gene silencing is crucially required for the successful therapeutics of short interfering RNA (siRNA). Here, a nanoparticle‐based delivery system is presented which assembles by layering siRNAs between protease degradable polypeptides to extend the therapeutic window. These tightly packed nanoparticles are efficiently taken up by cells by endocytosis, and the fabricated siRNAs are gradually released following intracellular degradation of the polypeptide layers. During cell division, the particles are distributed to the daughter cells. Due to the slow degradation through the multiple layers, the particles continuously release siRNA in all cells. Using this controlled release construct, the in vivo gene silencing effect of siRNA is consistent for an ultralong period of time (>3 weeks) with only a single treatment.     

A Sequentially Triggered Nanosystem for Precise Drug Delivery and Simultaneous Inhibition of Cancer Growth,Migration, and Invasion

The rational design of cancer‐targeted and bioresponsive drug delivery vehicles can enhance the anticancer efficacy of conventional chemotherapeutics and reduce their adverse side effects. However, the complexity of precise delivery and the ability to trigger drug release in specific tumor sites remain a challenging puzzle. Here, a sequentially triggered nanosystem composed of HER2 antibody with disulfide linkage as a surface decorator (HER2@NPs) is constructed for precise drug delivery and the simultaneous inhibition of cancer growth, migration, and invasion. The nanosystem actively accumulates in cancer cells, undergoes self‐immolative cleavage in response to biological thiols, and is degraded to form small nanoparticles. After internalization by receptor‐mediated endocytosis, the nanoparticles further disassemble under acidic conditions in the presence of lysozymes and cell lysates, leading to sequentially triggered drug release. The released payload triggers overproduction of reactive oxygen species and activates p53 and MAPKs pathways to induce cancer cell apoptosis. Moreover, HER2@NPs markedly suppress the migration and invasion of human bladder cancer cells at nontoxic concentrations. HER2@NPs demonstrate potent in vivo anticancer efficacy, but show no obvious histological damage to the major organs. Taken together, this study provides a valid tactic for the rational design of sequentially triggered nanosystems for precise drug delivery and cancer therapy.     

Effective and Selective Anti‐Cancer Protein Delivery via All‐Functions‐in‐One Nanocarriers Coupled with Visible Light‐Responsive,Reversible Protein Engineering

Efficient intracellular delivery of protein drugs and tumor‐specific activation of protein functions are critical toward anti‐cancer protein therapy. However, an omnipotent protein delivery system that can harmonize the complicated systemic barriers as well as spatiotemporally manipulate protein function is lacking. Herein, an “all‐functions‐in‐one” nanocarrier doped with photosensitizer (PS) is developed and coupled with reactive oxygen species (ROS)‐responsive, reversible protein engineering to realize cancer‐targeted protein delivery, and spatiotemporal manipulation of protein activities using long‐wavelength visible light (635 nm) at low power density (5 mW cm^?2). Particularly, RNase A is caged with H₂O₂‐cleavable phenylboronic acid to form 4‐nitrophenyl 4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)benzyl carbonate (NBC)‐modified RNase (RNBC), which is encapsulated in acid‐degradable, ketal‐crosslinked PEI (KPEI)‐based nanocomplexes (NCs) coated with PS‐modified hyaluronic acid (HA). Such NCs harmonize the critical processes for protein delivery, wherein HA coating renders NCs with long blood circulation and cancer cell targeting, and KPEI enables endosomal escape as well as acid‐triggered intracellular RNBC release. Tumor‐specific light irradiation generates H₂O₂ to kill cancer cells and restore the protein activity, thus achieving synergistic anti‐cancer efficacy. It is the first time to photomanipulate protein functions by coupling ROS‐cleavable protein caging with PS‐mediated ROS generation, and the “all‐functions‐in‐one” nanocarrier represents a promising example for the programmed anti‐cancer protein delivery.     

Biomimetic Natural Killer Membrane Camouflaged Polymeric Nanoparticle for Targeted Bioimaging

In the present study, a biomimetic nanoconstruct (BNc) with a multimodal imaging system is engineered using tumor homing natural killer cell membrane (NKM), near‐infrared (NIR) fluorescent dye, and gadolinium (Gd) conjugate‐based magnetic resonance imaging contrast agent onto the surface of a polymeric nanoparticle. The engineered BNc is 110 ± 20 nm in size and showed successful retention of NKM proteins. The magnetic properties of the BNc are found to be tunable from 2.1 ± 0.17 to 5.3 ± 0.5 mm ^?1 s^?1 under 14.1 T, by adjusting the concentration of Gd‐lipid conjugate onto the surface of the BNc. Confocal imaging and cell sorting analysis reveal a distinguishable cellular interaction of the BNc with MCF‐7 cells in comparison to that of bare polymeric nanoparticles suggesting the tumor homing properties of NKM camouflage system. The in vitro cellular interaction results are further confirmed by in vivo NIR fluorescent tumor imaging and ex vivo MR imaging, respectively. Pharmacokinetics and biodistribution analysis of the BNc show longer circulation half‐life (≈9.5 h) and higher tumor accumulation (10% of injected dose) in MCF‐7 induced tumor‐bearing immunodeficient NU/NU nude mice. Owing to the proven immunosurveillance potential of NK‐cell in the field of immunotherapy, the BNc engineered herein would hold promises in the design consideration of nanomedicine engineering.     

Engineered Proteinticles for Targeted Delivery of siRNA to Cancer Cells

Considering the problems of small interfering RNA (siRNA) delivery using traditional viral and nonviral vehicles, a new siRNA delivery system to enhance efficiency and safety needs to be developed. Here human ferritin‐based proteinticles are genetically engineered to simultaneously display various functional peptides on the surface of proteinticles: cationic peptide to capture siRNA, tumor cell targeting and penetrating peptides, and enzymatically cleaved peptide to release siRNA inside tumor cell. In the in vitro treatment of poly‐siRNA‐proteinticle complex, both of the tumor cell targeting and penetrating peptides are important for efficient delivery of siRNA, and the red fluorescent protein (RFP) expression in RFP‐expressing tumor cells is notably suppressed by the delivered siRNA with the complementary sequence to RFP mRNA. It seems that the human ferritin‐based proteinticle is an efficient, stable, and safe tool for siRNA delivery, having a great potential for application to in vivo cancer treatment. The unique feature of proteinticles is that multiple and functional peptides can be simultaneously and evenly placed and also easily switched on the proteinticle surface through a simple genetic modification, which is likely to make proteinticles appropriate for targeted delivery of siRNA to a wide range of cancer cells.     

A Fluorinated Bola‐Amphiphilic Dendrimer for On‐Demand Delivery of siRNA,via Specific Response to Reactive Oxygen Species

Functional materials capable of responding to stimuli intrinsic to diseases are extremely important for specific drug delivery at the disease site. However, developing on‐demand stimulus‐responsive vectors for targeted delivery is highly challenging. Here, a stimulus‐responsive fluorinated bola‐amphiphilic dendrimer is reported for on‐demand delivery of small interfering RNA (siRNA) in response to the characteristic high level of reactive oxygen species (ROS) in cancer cells. This dendrimer bears a ROS‐sensitive thioacetal in the hydrophobic core and positively charged poly(amidoamine) dendrons at the terminals, capable of interacting and compacting the negatively charged siRNA into nanoparticles to protect the siRNA and promote cellular uptake. The ROS‐sensitive feature of this dendrimer boosts specific and efficient disassembly of the siRNA/vector complexes in ROS‐rich cancer cells for effective siRNA delivery and gene silencing. Moreover, the fluorine tags in the vector enable ¹⁹F‐NMR analysis of the ROS‐responsive delivery process. In addition, this ingenious and distinct bola‐amphiphilic dendrimer is also able to combine the advantageous delivery features of both lipid and dendrimer vectors. Therefore, it represents an innovative on‐demand stimulus‐responsive delivery platform.     

Lipid‐Like Nanoparticles for Small Interfering RNA Delivery to Endothelial Cells

Here, nanoparticles composed of lipid‐like materials (lipidoids) to facilitate non‐viral delivery of small interfering RNA (siRNA) to endothelial cells (ECs) are developed. Nanoparticles composed of siRNA and lipidoids with small size (～200 nm) and positive charge (～34 mV) are formed by self‐assembly of lipidoids and siRNA. Ten lipidoids are synthesized and screened for their ability to facilitate the delivery of siRNA into ECs. Particles composed of leading lipidoids show significantly better delivery to ECs than a leading commercially available transfection reagent, Lipofectamine 2000. As a model of potential therapeutic application, nanoparticles composed of the top performing lipidoid, NA114, are studied for their ability to deliver siRNA targeting anti‐angiogenic factor (SHP‐1) to human ECs. Silencing of SHP‐1 expression significantly enhances EC proliferation and decreases EC apoptosis under a simulated ischemic condition.     

Injectable Hydrogels from Triblock Copolymers of Vitamin E‐Functionalized Polycarbonate and Poly(ethylene glycol) for Subcutaneous Delivery of Antibodies for Cancer Therapy

In this study, ‘ABA’‐type triblock copolymers of vitamin E‐functionalized polycarbonate and poly(ethylene glycol) , i.e., VitE_m‐PEG‐VitE_m, with extremely short hydrophobic block VitE_m, are synthesized and employed to form physically cross‐linked injectable hydrogels for local and sustained delivery of Herceptin. The hydrogels are formed at low concentrations (4–8 wt%). By varying polymer composition and concentration, the rheological behavior, porosity, and drug release properties of hydrogels are readily tunable. The in vitro antitumor specificity and efficacy of Herceptin in hydrogel and solution are investigated by MTT assay against normal and human breast cancer cell lines with different HER2 expression levels. The results demonstrate that the Herceptin‐loaded hydrogel is specific towards HER2‐overexpressing cancer cells and cytotoxic action is comparable to that of the Herceptin solution. The biocompatibility and biodegradability of hydrogel are evaluated in mice with subcutaneous injection by histological examination. It is observed that the hydrogel does not evoke a chronic inflammatory response and degrades within 6 weeks post administration. Biodistribution and anti‐tumor efficacy studies performed in BT474 tumor‐bearing mice show that single subcutaneous injection of Herceptin‐loaded hydrogel at a site close to the tumor enhances the retention of the antibody within the tumor. This leads to superior anti‐tumor efficacy as compared to intravenous (i.v.) and subcutaneous (s.c.) delivery of Herceptin in solution. The tumor size shrank by 77% at Day 28. When the hydrogel is injected at a distal location away from the tumor site, anti‐tumor efficacy is similar to that of weekly i.v. injections of Herceptin solution over 4 weeks, with the number of injections reduced from 4 to 1. These findings suggest that this hydrogel has great potential for use in subcutaneous and sustained delivery of antibodies to increase therapeutic efficacy and/or improve patient compliance.     

Dual‐Targeting Heparin‐Based Nanoparticles that Re‐Assemble in Blood for Glioma Therapy through Both Anti‐Proliferation and Anti‐Angiogenesis

The efficient and specific delivery of nanoparticles (NPs) to brain tumors is crucial for successful glioma treatment. Heparin‐based polymers decorated with two peptides self‐assemble into multi‐functional NPs that specifically target glioma cells. These NPs re‐self‐assemble to a smaller size in blood, which is beneficial for in‐vivo brain drug delivery. The hydrodynamic size of one type of these NPs is 63 ± 11 nm under blood‐mimic conditions (10% fetal bovine serum), but it is 164 ± 16 nm in water. Additionally their zeta potential is more neutral in the blood‐mimic conditions. Transmission electron microscopy reveals the morphology of the spherical NPs. In vitro experiments demonstrate that the NPs exhibit a high cellular uptake and the ability to efficiently discourage proliferation, endothelial‐lined vessels, and vasculogenic mimicry. In vivo studies demonstrate that the NPs can by‐pass the normal blood–brain and blood–(brain tumor) barriers and specifically accumulate in glioma tissues; moreover, they present an excellent anti‐glioma effect in subcutaneous/intracranial glioma‐bearing mice. Their superiority is due to their appropriate size in blood and the synergic effect arising from their targeting of two different receptors. The data suggests that these NPs are ideal for anti‐glioma therapy.     

Strategies for Delivering Nanoparticles across Tumor Blood Vessels

Nanoparticle transport across tumor blood vessels is a key step in nanoparticle delivery to solid tumors. However, the specific pathways and mechanisms of this nanoparticle delivery process are not fully understood. Here, the biological and physical characteristics of the tumor vasculature and the tumor microenvironment are explored and how these features affect nanoparticle transport across tumor blood vessels is discussed. The biological and physical methods to deliver nanoparticles into tumors are reviewed and paracellular and transcellular nanoparticle transport pathways are explored. Understanding the underlying pathways and mechanisms of nanoparticle tumor delivery will inform the engineering of safer and more effective nanomedicines for clinical translation.