Ligand-Functionalized Poly(ethylene glycol) Particles for Tumor Targeting and Intracellular Uptake

Engineering poly(ethylene glycol) particles for targeted drug delivery

Poly(ethylene glycol) (PEG) is considered to be the "gold standard" among the stealth polymers employed for drug delivery. Using PEG to modify or engineer particles has thus gained increasing interest because of the ability to prolong blood circulation time and reduce nonspecific biodistribution of particles in vivo, owing to the low fouling and stealth properties of PEG. In addition, endowing PEG-based particles with targeting and drug-loading properties is essential to achieve enhanced drug accumulation at target sites in vivo. In this feature article, we focus on recent work on the synthesis of PEG particles, in which PEG is the main component in the particles. We highlight different synthesis methods used to generate PEG particles, the influence of the physiochemical properties of PEG particles on their stealth and targeting properties, and the application of PEG particles in targeted drug delivery.

Dual stimuli-responsive mesoporous silica nanoparticles for efficient loading and smart delivery of doxorubicin to cancer with RGD-integrin targeting

The recent progress in nanoparticle applications, such as tumor-targeting, has enabled specific delivery of chemotherapeutics to malignant tissues with enhanced local efficacy while limiting side effects. However, existing delivery systems leave much room for improvement in terms of achieving enhanced colloidal stability in fluid medium, efficient targeting of intended sites, and effective release of therapeutic drugs into diseased cells. Here, an efficient stimuli-responsive nanocarrier for mammalian cells, termed RGD-NAMs, was developed, which enabled temperature- and pH-sensitive release of drug loads. The RGD-NAMs comprise two parts: a stimuli-responsive copolymer shell (NIBIm-AA-RGD) and drug-container core (MSNs). The RGD-NAMs have a stable drug-loading capacity with a marked difference in the release rate depending on the temperature and pH conditions. The RGD-NAMs also exhibit high colloidal stability in SBF (Stimulated body fluid) solutions and minimal toxicity in skeletal myoblasts (C2C12) and bovine arterial endothelial cells (BAEC). The doxorubicin-loaded RGD-NAMs induced a cytotoxic effect in a dose-dependent manner, which was furthered by an increase in temperature from 37 to 40 °C. Moreover, significant control of the release rate and the amount were achieved through pH change. This novel, smart drug-delivery system with high responsiveness to temperature and pH changes has wide application prospects in biomedical fields, including the theragnosis of tumors and vascular diseases.

Magnetically Enhanced Intracellular Uptake of Superparamagnetic Iron Oxide Nanoparticles for Antitumor Therapy

Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely employed in biomedical fields, including targeted delivery of antitumor therapy. Conventional magnetic tumor targeting has used simple static magnetic fields (SMFs), which cause SPIONs to linearly aggregate into a long chain-like shape. Such agglomeration greatly hinders the intracellular targeting of SPIONs into tumors, thus reducing the therapeutic efficacy. In this study, we investigated the enhancement of the intracellular uptake of SPIONs through the application of rotating magnetic fields (RMFs). Based on the physical principles of SPION chain disassembly, we investigated physical parameters to predict the chain length favorable for intracellular uptake. Our prediction was validated by clear visualization of the intracellular distributions of SPIONs in tumor cells at both cellular and three-dimensional microtissue levels. To identify the potential therapeutic effects of enhanced intracellular uptake, magnetic hyperthermia as antitumor therapy was investigated under varying conditions of magnetic hyperthermia and RMFs. The results showed that enhanced intracellular uptake reduced magnetic hyperthermia time and strength as well as particle concentration. The proposed method will be useful in the development of techniques to determine the optimized physical conditions for the enhanced intracellular uptake of SPIONs in antitumor therapy.

Fe-involved nanostructures act as photothermal transduction agents in cancer photothermal therapy

Cancer, a disease notorious for its difficult therapy regimen, has long puzzled researchers. Despite attempts to cure cancer using surgery, chemotherapy, radiotherapy, and immunotherapy, their effectiveness is limited. Recently, photothermal therapy (PTT), a rising strategy, has gained attention. PTT can increase the surrounding temperature of cancer tissues and cause damage to them. Fe is widely used in PTT nanostructures due to its strong chelating ability, good biocompatibility, and the potential to induce ferroptosis. In recent years, many nanostructures incorporating Fe3+ have been developed. In this article, we summarize PTT nanostructures containing Fe and introduce their synthesis and therapy strategy. However, PTT nanostructures containing Fe are still in their infancy, and more effort must be devoted to improving their effectiveness so that they can eventually be used in clinics.

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

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

Structure-function relationships in polymeric multilayer capsules designed for cancer drug delivery

The targeted delivery of cancer drugs to tumor-specific molecular targets represents a major challenge in modern personalized cancer medicine. Engineering of micron and submicron polymeric multilayer capsules allows the obtaining of multifunctional theranostic systems serving as controllable stimulus-responsive tools with a high clinical potential to be used in cancer therapy and detection. The functionalities of such theranostic systems are determined by the design and structural properties of the capsules. This review (1) describes the current issues in designing cancer cell-targeting polymeric multilayer capsules, (2) analyzes the effects of the interactions of the capsules with the cellular and molecular constituents of biological fluids, and (3) presents the key structural parameters determining the effectiveness of capsule targeting. The influence of the morphological and physicochemical parameters and the origin of the structural components and surface ligands on the functional activity of polymeric multilayer capsules at the molecular, cellular, and whole-body levels are summarized. The basic structural and functional principles determining the future trends of theranostic capsule development are established and discussed.

Nano-Based Theranostic Platforms for Breast Cancer: A Review of Latest Advancements

Breast cancer (BC) is a highly metastatic multifactorial disease with various histological and molecular subtypes. Due to recent advancements, the mortality rate in BC has improved over the past five decades. Detection and treatment of many cancers are now possible due to the application of nanomedicine in clinical practice. Nanomedicine products such as Doxil^® and Abraxane^® have already been extensively used for BC adjuvant therapy with favorable clinical outcomes. However, these products were designed initially for generic anticancer purposes and not specifically for BC treatment. With a better understanding of the molecular biology of BC, several novel and promising nanotherapeutic strategies and devices have been developed in recent years. In this context, multi-functionalized nanostructures are becoming potential carriers for enhanced chemotherapy in BC patients. To design these nanostructures, a wide range of materials, such as proteins, lipids, polymers, and hybrid materials, can be used and tailored for specific purposes against BC. Selective targeting of BC cells results in the activation of programmed cell death in BC cells and can be considered a promising strategy for managing triple-negative BC. Currently, conventional BC screening methods such as mammography, digital breast tomosynthesis (DBT), ultrasonography, and magnetic resonance imaging (MRI) are either costly or expose the user to hazardous radiation that could harm them. Therefore, there is a need for such analytical techniques for detecting BC that are highly selective and sensitive, have a very low detection limit, are durable, biocompatible, and reproducible. In detecting BC biomarkers, nanostructures are used alone or in conjunction with numerous molecules. This review intends to highlight the recent advances in nanomedicine in BC treatment and diagnosis, emphasizing the targeting of BC cells that overexpress receptors of epidermal growth factors. Researchers may gain insight from these strategies to design and develop more tailored nanomedicine for BC to achieve further improvements in cancer specificity, antitumorigenic effects, anti-metastasis effects, and drug resistance reversal effects.

Protein precoating modulates biomolecular coronas and nanocapsule-immune cell interactions in human blood

The biomolecular corona that forms on particles upon contact with blood plays a key role in the fate and utility of nanomedicines. Recent studies have shown that precoating nanoparticles with serum proteins can improve the biocompatibility and stealth properties of nanoparticles. However, it is not fully clear how precoating influences biomolecular corona formation and downstream biological responses. Herein, we systematically examine three precoating strategies by coating bovine serum albumin (single protein), fetal bovine serum (FBS, mixed proteins without immunoglobulins), or bovine serum (mixed proteins) on three nanoparticle systems, namely supramolecular template nanoparticles, metal-phenolic network (MPN)-coated template (core-shell) nanoparticles, and MPN nanocapsules (obtained after template removal). The effect of protein precoating on biomolecular corona compositions and particle-immune cell interactions in human blood was characterized. In the absence of a pre-coating, the MPN nanocapsules displayed lower leukocyte association, which correlated to the lower amount (by 2-3 fold) of adsorbed proteins and substantially fewer immunoglobulins (more than 100 times) in the biomolecular corona relative to the template and core-shell nanoparticles. Among the three coating strategies, FBS precoating demonstrated the most significant reduction in leukocyte association (up to 97% of all three nanoparticles). A correlation analysis highlights that immunoglobulins and apolipoproteins may regulate leukocyte recognition. This study demonstrates the impact of different precoating strategies on nanoparticle-immune cell association and the role of immunoglobulins in bio-nano interactions.

PEGylation of Metal Oxide Nanoparticles Modulates Neutrophil Extracellular Trap Formation

Novel metal oxide nanoparticle (NP) contrast agents may offer safety and functionality advantages over conventional gadolinium-based contrast agents (GBCAs) for cancer diagnosis by magnetic resonance imaging. However, little is known about the behavior of metal oxide NPs, or of their effect, upon coming into contact with the innate immune system. As neutrophils are the body's first line of defense, we sought to understand how manganese oxide and iron oxide NPs impact leukocyte functionality. Specifically, we evaluated whether contrast agents caused neutrophils to release web-like fibers of DNA known as neutrophil extracellular traps (NETs), which are known to enhance metastasis and thrombosis in cancer patients. Murine neutrophils were treated with GBCA, bare manganese oxide or iron oxide NPs, or poly(lactic-co-glycolic acid) (PLGA)-coated metal oxide NPs with different incorporated levels of poly(ethylene glycol) (PEG). Manganese oxide NPs elicited the highest NETosis rates and had enhanced neutrophil uptake properties compared to iron oxide NPs. Interestingly, NPs with low levels of PEGylation produced more NETs than those with higher PEGylation. Despite generating a low rate of NETosis, GBCA altered neutrophil cytokine expression more than NP treatments. This study is the first to investigate whether manganese oxide NPs and GBCAs modulate NETosis and reveals that contrast agents may have unintended off-target effects which warrant further investigation.

Bioresponsive Polyphenol-Based Nanoparticles as Thrombolytic Drug Carriers

Thrombolytic (clot-busting) therapies with plasminogen activators (PAs) are first-line treatments against acute thrombosis and ischemic stroke. However, limitations such as narrow therapeutic windows, low success rates, and bleeding complications hinder their clinical use. Drug-loaded polyphenol-based nanoparticles (NPs) could address these shortfalls by delivering a more targeted and safer thrombolysis, coupled with advantages such as improved biocompatibility and higher stability in vivo. Herein, a template-mediated polyphenol-based supramolecular assembly strategy is used to prepare nanocarriers of thrombolytic drugs. A thrombin-dependent drug release mechanism is integrated using tannic acid (TA) to cross-link urokinase-type PA (uPA) and a thrombin-cleavable peptide on a sacrificial mesoporous silica template via noncovalent interactions. Following drug loading and template removal, the resulting NPs retain active uPA and demonstrate enhanced plasminogen activation in the presence of thrombin (1.14-fold; p < 0.05). Additionally, they display lower association with macrophage (RAW 264.7) and monocytic (THP-1) cell lines (43 and 7% reduction, respectively), reduced hepatic accumulation, and delayed blood clearance in vivo (90% clearance at 60 min vs 5 min) compared with the template-containing NPs. Our thrombin-responsive, polyphenol-based NPs represent a promising platform for advanced drug delivery applications, with potential to improve thrombolytic therapies.

Intelligent Pore Switch of Hollow Mesoporous Organosilica Nanoparticles for High Contrast Magnetic Resonance Imaging and Tumor-Specific Chemotherapy

Hollow mesoporous organosilica nanoparticles (HMONs) are widely considered as a promising drug nanocarrier, but the loaded drugs can easily leak from HMONs, resulting in the considerably decreased drug loading capacity and increased biosafety risk. This study reports the smart use of core/shell Fe₃O₄/Gd₂O₃ (FG) hybrid nanoparticles as a gatekeeper to block the pores of HMONs, which can yield an unreported large loading content (up to 20.4%) of DOX. The conjugation of RGD dimer (R2) onto the DOX-loaded HMON with FG capping (D@HMON@FG@R2) allowed for active tumor-targeted delivery. The aggregated FG in D@HMON@FG@R2 could darken the normal tissue surrounding the tumor due to the high r₂ value (253.7 mM^-1 s^-1) and high r₂/r₁ ratio (19.13), and the intratumorally released FG as a result of reducibility-triggered HMON degradation could brighten the tumor because of the high r₁ value (20.1 mM^-1 s^-1) and low r₂/r₁ ratio (7.01), which contributed to high contrast magnetic resonance imaging (MRI) for guiding highly efficient tumor-specific DOX release and chemotherapy.

Recent Advances in Metal-Phenolic Networks for Cancer Theranostics

Nanomedicine integrates different functional materials to realize the customization of carriers, aiming at increasing the cancer therapeutic efficacy and reducing the off-target toxicity. However, efforts on developing new drug carriers that combine precise diagnosis and accurate treatment have met challenges of uneasy synthesis, poor stability, difficult metabolism, and high cytotoxicity. Metal-phenolic networks (MPNs), making use of the coordination between phenolic ligands and metal ions, have emerged as promising candidates for nanomedicine, most notably through the service as multifunctional theranostic nanoplatforms. MPNs present unique properties, such as rapid preparation, negligible cytotoxicity, and pH responsiveness. Additionally, MPNs can be further modified and functionalized to meet specific application requirements. Here, the classification of polyphenols is first summarized, followed by the introduction of the properties and preparation strategies of MPNs. Then, their recent advances in biomedical sciences including bioimaging and anti-tumor therapies are highlighted. Finally, the main limitations, challenges, and outlooks regarding MPNs are raised and discussed.

Cationic Liposome Decorated with Cyclic RGD Peptide for Targeted Delivery of anti-STAT3 siRNA to Melanoma Cancer Cells

Gene therapy is regarded as a valuable strategy for efficient cancer treatment. However, the design of effective delivery systems that can deliver gene materials such as siRNA specifically to the tumour tissues plays a pivotal role in cancer therapy. For this reason, a targeted cationic liposome for melanoma treatment was developed. This system consists of cyclic RGD peptide conjugated to DSPE-PEG2000, cholesterol, DOTAP, and DSPC as cationic and neutral lipids, respectively. Cyclic RGD was selected based on speculation that cyclic RGD would effectively transport anti-signal transducer and activator of transcription 3 (STAT3) siRNA into melanoma cell via integrin receptors. The prepared liposomes provided excellent stability against electrolyte and serum nucleases. Targeted liposomes remarkably exhibited higher cellular internalisation in comparison with the non-targeted system in flow cytometry and confocal microscopy. Furthermore, incorporating peptide on the surface of liposomes resulted in considerably high cytotoxicity, a 2.1-times raise in apoptosis induction, and a significantly enhanced STAT3 gene suppression as compared with the corresponding non-targeted formulation on B16F10 murine melanoma cells. Whole-body imaging confirmed the more significant tumour accumulation of targeted liposomes in B16F10 melanoma xenograft tumour-bearing mice. Consequently, c-RGD peptide modified liposome suggests a promising option for specific siRNA delivery into melanoma cells.

Modifications of polysaccharide-based biomaterials under structure-property relationship for biomedical applications

Polysaccharides are well accepted biomaterials that have attracted considerable attention. Compared with other materials under research, polysaccharides show unique advantages: they are available in nature and are normally easily acquired, those acquired from nature show favorable immunogenicity, and are biodegradable and bioavailable. The bioactivity and possible applications are based on their chemical structure; however, naturally acquired polysaccharides sometimes have unwanted flaws that limit further applications. For this reason, carefully summarizing the possible modifications of polysaccharides to improve them is crucial. Structural modifications can not only provide polysaccharides with additional functional groups but also change their physicochemical properties. This review based on the structure-property relation summarizes the common chemical modifications of polysaccharides, the related bioactivity changes, possible functionalization methods, and major possible biomedical applications based on modified polysaccharides.

Quantitatively Tracking Bio-Nano Interactions of Metal-Phenolic Nanocapsules by Mass Cytometry

Polymer nanocapsules, with a hollow structure, are increasingly finding widespread use as drug delivery carriers; however, quantitatively evaluating the bio-nano interactions of nanocapsules remains challenging. Herein, poly(ethylene glycol) (PEG)-based metal-phenolic network (MPN) nanocapsules of three sizes (50, 100, and 150 nm) are engineered via supramolecular template-assisted assembly and the effect of the nanocapsule size on bio-nano interactions is investigated using in vitro cell experiments, ex vivo whole blood assays, and in vivo rat models. To track the nanocapsules by mass cytometry, a preformed gold nanoparticle (14 nm) is encapsulated into each PEG-MPN nanocapsule. The results reveal that decreasing the size of the PEG-MPN nanocapsules from 150 to 50 nm leads to reduced association (up to 70%) with phagocytic blood cells in human blood and prolongs in vivo systemic exposure in rat models. The findings provide insights into MPN-based nanocapsules and represent a platform for studying bio-nano interactions.

Influence of Poly(ethylene glycol) Molecular Architecture on Particle Assembly and Ex Vivo Particle-Immune Cell Interactions in Human Blood

Poly(ethylene glycol) (PEG) is widely used in particle assembly to impart biocompatibility and stealth-like properties in vivo for diverse biomedical applications. Previous studies have examined the effect of PEG molecular weight and PEG coating density on the biological fate of various particles; however, there are few studies that detail the fundamental role of PEG molecular architecture in particle engineering and bio-nano interactions. Herein, we engineered PEG particles using a mesoporous silica (MS) templating method and investigated how the PEG building block architecture impacted the physicochemical properties (e.g., surface chemistry and mechanical characteristics) of the PEG particles and subsequently modulated particle-immune cell interactions in human blood. Varying the PEG architecture from 3-arm to 4-arm, 6-arm, and 8-arm generated PEG particles with a denser, stiffer structure, with increasing elastic modulus from 1.5 to 14.9 kPa, inducing an increasing level of immune cell association (from 15% for 3-arm to 45% for 8-arm) with monocytes. In contrast, the precursor PEG particles with the template intact (MS@PEG) were stiffer and generally displayed higher levels of immune cell association but showed the opposite trend-immune cell association decreased with increasing PEG arm numbers. Proteomics analysis demonstrated that the biomolecular corona that formed on the PEG particles minimally influenced particle-immune cell interactions, whereas the MS@PEG particle-cell interactions correlated with the composition of the corona that was abundant in histidine-rich glycoproteins. Our work highlights the role of PEG architecture in the design of stealth PEG-based particles, thus providing a link between the synthetic nature of particles and their biological behavior in blood.

Controllable synthesis of iron-polyphenol colloidal nanoparticles with composition-dependent photothermal performance

Iron-polyphenol nanoparticles are usually prepared with nontoxic plant polyphenols as a main building block, which are an emerging photothermal agent for photothermal therapy. However, till now, few works have been made on the controllable synthesis of iron-polyphenol nanoparticles with tunable composition, as well as investigation of the relationship between material composition and photothermal property. In the present study, iron-polyphenol colloidal nanoparticles with tunable diameter (21-303 nm) and ion content (9.2-97.6 mg/g), as well as high colloidal stability are successfully synthesized using different polyphenols (such as tannic acid, epigallocatechin gallate, gallic acid, epicatechin and proanthocyanidin) as a ligand. In addition, photothermal performance is highly dependent on the organic ligand, iron content and particle size. Higher iron content and smaller diameter can contribute to higher photothermal performance. The iron-polyphenol nanoparticles with the optimal iron content and particle size are selected as a photothermal agent. They can effectively inhibit the tumour growth in vivo. The current work demonstrates a general synthesis strategy for iron-polyphenol colloidal nanoparticles with tailorable composition and clarifies the relationship between material composition and photothermal performance. Moreover, it is conductive to the rational design of polyphenol-based photothermal agents for theranostic applications.

Microemulsion-Assisted Templating of Metal-Stabilized Poly(ethylene glycol) Nanoparticles

Poly(ethylene glycol) (PEG) is well known to endow nanoparticles (NPs) with low-fouling and stealth-like properties that can reduce immune system clearance in vivo, making PEG-based NPs (particularly sub-100 nm) of interest for diverse biomedical applications. However, the preparation of sub-100 nm PEG NPs with controllable size and morphology is challenging. Herein, we report a strategy based on the noncovalent coordination between PEG-polyphenolic ligands (PEG-gallol) and transition metal ions using a water-in-oil microemulsion phase to synthesize sub-100 nm PEG NPs with tunable size and morphology. The metal-phenolic coordination drives the self-assembly of the PEG-gallol/metal NPs: complexation between Mn^II and PEG-gallol within the microemulsions yields a series of metal-stabilized PEG NPs, including 30-50 nm solid and hollow NPs, depending on the Mn^II/gallol feed ratio. Variations in size and morphology are attributed to the changes in hydrophobicity of the PEG-gallol/Mn^II complexes at varying Mn^II/gallol ratios based on contact angle measurements. Small-angle X-ray scattering analysis, which is used to monitor the particle size and intermolecular interactions during NP evolution, reveals that ionic interactions are the dominant driving force in the formation of the PEG-gallol/Mn^II NPs. pH and cytotoxicity studies, and the low-fouling properties of the PEG-gallol/Mn^II NPs confirm their high biocompatibility and functionality, suggesting that PEG polyphenol-metal NPs are promising systems for biomedical applications.

Person-Specific Biomolecular Coronas Modulate Nanoparticle Interactions with Immune Cells in Human Blood

When nanoparticles interact with human blood, a multitude of plasma components adsorb onto the surface of the nanoparticles, forming a biomolecular corona. Corona composition is known to be influenced by the chemical composition of nanoparticles. In contrast, the possible effects of variations in the human blood proteome between healthy individuals on the formation of the corona and its subsequent interactions with immune cells in blood are unknown. Herein, we prepared and examined a matrix of 11 particles (including organic and inorganic particles of three sizes and five surface chemistries) and plasma samples from 23 healthy donors to form donor-specific biomolecular coronas (personalized coronas) and investigated the impact of the personalized coronas on particle interactions with immune cells in human blood. Among the particles examined, poly(ethylene glycol) (PEG)-coated mesoporous silica (MS) particles, irrespective of particle size (800, 450, or 100 nm in diameter), displayed the widest range (up to 60-fold difference) of donor-dependent variance in immune cell association. In contrast, PEG particles (after MS core removal) of 860, 518, or 133 nm in diameter displayed consistent stealth behavior (negligible cell association), irrespective of plasma donor. For comparison, clinically relevant PEGylated doxorubicin-encapsulated liposomes (Doxil) (74 nm in diameter) showed significant variance in association with monocytes and B cells across all plasma donors studied. An in-depth proteomic analysis of each biomolecular corona studied was performed, and the results were compared against the nanoparticle-blood cell association results, with individual variance in the proteome driving differential association with specific immune cell types. We identified key immunoglobulin and complement proteins that explicitly enriched or depleted within the corona and which strongly correlated with the cell association pattern observed across the 23 donors. This study demonstrates how plasma variance in healthy individuals significantly influences the blood immune cell interactions of nanoparticles.

Bispecific antibody (HER2 × mPEG) enhances anti-cancer effects by precise targeting and accumulation of mPEGylated liposomes

Targeted antibodies and methoxy-PEGylated nanocarriers have gradually become a mainstream of cancer therapy. To increase the anti-cancer effects of targeted antibodies combined with mPEGylated liposomes (mPEG-liposomes), we describe a bispecific antibody in which an anti-methoxy-polyethylene glycol scFv (αmPEG scFv) was fused to the C-terminus of an anti-HER2 (αHER2) antibody to generate a HER2 × mPEG BsAb that retained the original efficacy of a targeted antibody while actively attracting mPEG-liposomes to accumulate at tumor sites. HER2 ×mPEG BsAb can simultaneously bind to HER2-high expressing MCF7/HER2 tumor cells and mPEG molecules on mPEG-liposomal doxorubicin (Lipo-Dox). Pre-incubation of HER2 × mPEG BsAb with cells increased the endocytosis of Lipo-DiD and enhanced the cytotoxicity of Lipo-Dox to MCF7/HER2 tumor cells. Furthermore, pre-treatment of HER2 × mPEG BsAb enhanced the tumor accumulation and retention of Lipo-DiR 2.2-fold in HER2-high expressing MCF7/HER2 tumors as compared to HER2-low expressing MCF7/neo1 tumors. Importantly, HER2 × mPEG BsAb plus Lipo-Dox significantly suppressed tumor growth as compared to control BsAb plus Lipo-Dox in MCF7/HER2 tumor-bearing mice. These results indicate that HER2 × mPEG BsAb can enhance tumor accumulation of mPEG-liposomes to improve the therapeutic efficacy of combination treatment. Anti-mPEG scFv can be fused to any kind of targeted antibody to generate BsAbs to actively attract mPEG-drugs and improve anti-cancer efficacy. STATEMENT OF SIGNIFICANCE: Antibody targeted therapy and PEGylated drugs have gradually become the mainstream of cancer therapy. To enhance the anti-cancer effects of targeted antibodies combined with PEGylated drugs is very important. To this aim, we fused an anti-PEG scFv to the C-terminal of HER2 targeted antibodies to generate a HER2×mPEG bispecific antibody (BsAb) to retain the original efficacy of targeted antibody whilst actively attract mPEG-liposomal drugs to accumulate at tumor sites. The present study demonstrates pre-treatment of HER2×mPEG BsAb can enhance tumor accumulation of mPEG-liposomal drugs to improve the therapeutic efficacy of combination treatment. Anti-mPEG scFv can be fused to any kind of targeted antibody to generate BsAbs to actively attract mPEG-drugs and improve anti-cancer efficacy.

Modulating the Selectivity and Stealth Properties of Ellipsoidal Polymersomes through a Multivalent Peptide Ligand Display

There is a need for improved nanomaterials to simultaneously target cancer cells and avoid non-specific clearance by phagocytes. An ellipsoidal polymersome system is developed with a unique tunable size and shape property. These particles are functionalized with in-house phage-display cell-targeting peptide to target a medulloblastoma cell line in vitro. Particle association with medulloblastoma cells is modulated by tuning the peptide ligand density on the particles. These polymersomes has low levels of association with primary human blood phagocytes. The stealth properties of the polymersomes are further improved by including the peptide targeting moiety, an effect that is likely driven by the peptide protecting the particles from binding blood plasma proteins. Overall, this ellipsoidal polymersome system provides a promising platform to explore tumor cell targeting in vivo.

Recent advances in molecular imaging of atherosclerotic plaques and thrombosis

As the complications of atherosclerosis such as myocardial infarction and stroke are still one of the leading causes of mortality worldwide, the development of new diagnostic tools for the early detection of plaque instability and thrombosis is urgently needed. Advanced molecular imaging probes based on functional nanomaterials in combination with cutting edge imaging techniques are now paving the way for novel and unique approaches to monitor the inflammatory progress in atherosclerosis. This review focuses on the development of various molecular probes for the diagnosis of plaques and thrombosis in atherosclerosis, along with perspectives of their diagnostic applications in cardiovascular diseases. Specifically, we summarize the biological targets that can be used for atherosclerosis and thrombosis imaging. Then we describe the emerging molecular imaging techniques based on the utilization of engineered nanoprobes together with their challenges in clinical translation.

Poly(ethylene glycol)-mediated mineralization of metal–organic frameworks

Scalable mineralization of zeolitic imidazolate framework-8 nanoparticles with versatility of cargo encapsulation and excellent colloidal dispersibility and stability is engineered using poly(ethylene glycol) as the mineralizer for therapeutic delivery.

Sono-Polymerization of Poly(ethylene glycol)-Based Nanoparticles for Targeted Drug Delivery

Engineering functional nanoparticles (NPs) with low nonspecific interactions and a high specific targeting property is highly desired for improved drug delivery. Herein, we report a targeted poly(ethylene glycol) (PEG)-based chemotherapy system synthesized via a catalyst-free sono-polymerization process for drug delivery. The polymerization process was fast (20 min), and different monomers were able to be polymerized to form NPs in a one-pot process. Glutathione (GSH)-responsive platinum prodrugs and fluorescent dyes could be encapsulated in NPs by amidation formation. Cyclic peptides containing Arg-Gly-Asp (RGD)-modified PEG-based NPs possessed a much higher cell targeting (∼90%) than the unmodified PEG-based NPs (∼10%) after a 12 h incubation with U87 MG cells, which could improve drug delivery efficacy. The IC₅₀ (50% inhibitory concentration) could also be reduced more than 50% compared to the nontargeted PEG-based NPs. Importantly, these PEG-based NPs can be freeze-dried into a powder form and redispersed in an aqueous solution without aggregation, which may facilitate the storage and transportation of nanomedicine. This study establishes a green and efficient method to engineer targeted drug carriers for drug delivery.