Zwitterionic Janus Dendrimer with distinct functional disparity for enhanced protein delivery

Telodendrimer functionalized hydrogel platform for sustained antibiotics release in infection control

Wound infection commonly causes delayed healing, especially in the setting of chronic wounds. Local release of antibiotics is considered a viable approach to treat chronic wounds. We have developed a versatile telodendrimer (TD) platform for efficient loading of charged antibiotic molecules via a combination of multivalent and synergistic charge and hydrophobic interactions. The conjugation of TD in biocompatible hydrogel allows for topical application to provide sustained antibiotic release. Notably, a drug loading capacity as high as 20 % of the drug-to-resin dry weight ratio can be achieved. The payload content (PC) and release profile of the various antibiotics can be optimized by fine-tuning TD density and valency in hydrogel based on the charge and hydrophobic features of the drug, e.g., polymyxin B (PMB), gentamycin (GM), and daptomycin (Dap), for effective infection control. We have shown that hydrogel with moderately reduced TD density demonstrates a more favorable release profile than hydrogel with higher TD density. Antibiotics loaded in TD hydrogel have comparable antimicrobial potency and reduced cytotoxicity compared to the free antibiotics due to a prolonged, controlled drug release profile. In a mouse model of skin and soft tissue infection, the subcutaneous administration of PMB-loaded TD hydrogel effectively eliminated the bacterial burden. Overall, these results suggest that engineerable TD hydrogels have great potential as a topical treatment to control infection for wound healing. STATEMENT OF SIGNIFICANCE: Wound infection causes a significant delay in the wound healing process, which results in a significant financial and resource burden to the healthcare system. PEGA-telodendrimer (TD) resin hydrogel is an innovative and versatile platform that can be fine-tuned to efficiently encapsulate different antibiotics by altering charged and hydrophobic structural moieties. Additionally, this platform is advantageous as the TD density in the resin can also be fine-tuned to provide the desired antibiotic payload release profile. Sustained antibiotics release through optimization of TD density provides a prolonged therapeutic window and reduces burst release-induced cytotoxicity compared to conventional antibiotics application. Studies in a preclinical mouse model of bacteria-induced skin and soft tissue infection demonstrated promising therapeutic efficacy as evidenced by effective infection control and prolonged antibacterial efficacy of antibiotics-loaded PEGA-TD resin. In conclusion, the PEGA-TD resin platform provides a highly customizable approach for effective antibiotics release with significant potential for topical application to treat various bacterial wound infections to promote wound healing.

In Vivo Applications of Dendrimers: A Step toward the Future of Nanoparticle-Mediated Therapeutics

Over the last few years, the development of nanotechnology has allowed for the synthesis of many different nanostructures with controlled sizes, shapes, and chemical properties, with dendrimers being the best-characterized of them. In this review, we present a succinct view of the structure and the synthetic procedures used for dendrimer synthesis, as well as the cellular uptake mechanisms used by these nanoparticles to gain access to the cell. In addition, the manuscript reviews the reported in vivo applications of dendrimers as drug carriers for drugs used in the treatment of cancer, neurodegenerative diseases, infections, and ocular diseases. The dendrimer-based formulations that have reached different phases of clinical trials, including safety and pharmacokinetic studies, or as delivery agents for therapeutic compounds are also presented. The continuous development of nanotechnology which makes it possible to produce increasingly sophisticated and complex dendrimers indicates that this fascinating family of nanoparticles has a wide potential in the pharmaceutical industry, especially for applications in drug delivery systems, and that the number of dendrimer-based compounds entering clinical trials will markedly increase during the coming years.

Unveiling cytokine charge disparity as a potential mechanism for immune regulation

Cytokines are small signaling proteins that regulate the immune responses to infection and tissue damage. Surface charges of cytokines determine their in vivo fate in immune regulation, e.g., half-life and distribution. The overall negative charges in the extracellular microenvironment and the acidosis during inflammation and infection may differentially impact cytokines with different surface charges for fine-tuned immune regulation via controlling tissue residential properties. However, the trend and role of cytokine surface charges has yet to be elucidated in the literature. Interestingly, we have observed that most pro-inflammatory cytokines have a negative charge, while most anti-inflammatory cytokines and chemokines have a positive charge. In this review, we extensively examined the surface charges of all cytokines and chemokines, summarized the pharmacokinetics and tissue adhesion of major cytokines, and analyzed the link of surface charge with cytokine biodistribution, activation, and function in immune regulation. Additionally, we identified that the general trend of charge disparity between pro- and anti-inflammatory cytokines represents a unique opportunity to develop precise immune modulation approaches, which can be applied to many inflammation-associated diseases including solid tumors, chronic wounds, infection, and sepsis.

Engineering Nanotrap Hydrogel for Immune Modulation in Wound Healing

Imbalanced immune regulation leads to the abnormal wound healing process, e.g., chronic unhealing wound or hypertrophic scar formation. Thus, the attenuation of the overflowing inflammatory factors is a viable approach to maintain the homeostatic immune regulation to facilitate normal wound healing. A versatile telodendrimer (TD) nanotrap (NT) platform is developed for efficient biomolecular protein binding. The conjugation of TD NT in size-exclusive biocompatible hydrogel resin allows for topical application for cytokine scavenging. Fine-tuning the TD NT density/valency in hydrogel resin controls resin swelling, optimizes molecular diffusion, and improves cytokine capture for effective immune modulation. The hydrogel with reduced TD NT density allows for higher protein/cytokine adsorption capacity with faster kinetics, due to the reduced barrier of TD NT nano-assembly. The positively charged TD NT hydrogel exhibits superior removal of negatively charged proinflammatory cytokines from the lipopolysaccharide (LPS, a potent endotoxin) primed immune cell culture medium. The negatively charged TD NT hydrogel removes positively charged anti-inflammatory cytokines efficiently from cell culture medium. TD NT hydrogel effectively constrains the local inflammation induced by subcutaneous LPS injection in mice. These results indicate the great potential applications of the engineered TD NT hydrogel as topical immune modulatory treatments to attenuate local inflammation.

A novel biosensing platform for detection of glaucoma biomarker GDF15 via an integrated BLI-ELASA strategy

Glaucoma is a leading cause of irreversible blindness worldwide. Early discovery and prioritized intervention significantly impact its prognosis. Precise monitoring of the biomarker GDF15 contributes towards effective diagnosis and assessment of glaucoma. In this study, we demonstrate that GDF15 monitoring can also aid screening for glaucoma risk and early diagnosis. We obtained an aptamer (APT2TM) with high affinity, high specificity, and high stability for binding to both human-derived and rat-derived GDF15. Simulation results showed that the binding capabilities of APT2TM are mainly affected by the interplay between van der Waals forces and polar solvation energy, and that salt bridges and hydrogen bonds play critical roles. We then integrated an enzyme-linked aptamer sandwich assay (ELASA) into a biolayer interferometry (BLI) system to develop an automated, high-throughput, real-time monitoring BLI-ELASA biosensing platform. This platform exhibited a wide linear detection window (10-810 pg/mL range) and high sensitivity for GDF15 (detection limit of 5-6 pg/mL). Moreover, we confirmed its excellent performance when applied to GDF15 quantification in real samples from glaucomatous rats and clinical patients. We believe that this technology represents a robust, convenient, and cost-effective approach for risk screening, early diagnosis, and animal modeling evaluation of glaucoma in the near future.

Properties and Bioapplications of Amphiphilic Janus Dendrimers: A Review

Amphiphilic Janus dendrimers are arrangements containing both hydrophilic and hydrophobic units, capable of forming ordered aggregates by intermolecular noncovalent interactions between the dendrimer units. Compared to conventional dendrimers, these molecular self-assemblies possess particular and effective attributes i.e., the presence of different terminal groups, essential to design new elaborated materials. The present review will focus on the pharmaceutical and biomedical application of amphiphilic Janus dendrimers. Important information for the development of novel optimized pharmaceutical formulations, such as structural classification, synthetic pathways, properties and applications, will offer the complete characterization of this type of Janus dendrimers. This work will constitute an up-to-date background for dendrimer specialists involved in designing amphiphilic Janus dendrimer-based nanomaterials for future innovations in this promising field.

Hybrid Molecules Consisting of Lysine Dendrons with Several Hydrophobic Tails: A SCF Study of Self-Assembling

In this article, we used the numerical self-consistent field method of Scheutjens-Fleer to study the micellization of hybrid molecules consisting of one polylysine dendron with charged end groups and several linear hydrophobic tails attached to its root. The main attention was paid to spherical micelles and the determination of the range of parameters at which they can appear. A relationship has been established between the size and internal structure of the resulting spherical micelles and the length and number of hydrophobic tails, as well as the number of dendron generations. It is shown that the splitting of the same number of hydrophobic monomers from one long tail into several short tails leads to a decrease in the aggregation number and, accordingly, the number of terminal charges in micelles. At the same time, it was shown that the surface area per dendron does not depend on the number of hydrophobic monomers or tails in the hybrid molecule. The relationship between the structure of hybrid molecules and the electrostatic properties of the resulting micelles has also been studied. It is found that the charge distribution in the corona depends on the number of dendron generations G in the hybrid molecule. For a small number of generations (up to G=3), a standard double electric layer is observed. For a larger number of generations (G=4), the charges of dendrons in the corona are divided into two populations: in the first population, the charges are in the spherical layer near the boundary between the micelle core and shell, and in the second population, the charges are near the periphery of the spherical shell. As a result, a part of the counterions is localized in the wide region between them. These results are of potential interest for the use of spherical dendromicelles as nanocontainers for drug delivery.

Robust Construction of Supersmall Zwitterionic Micelles Based on Hyperbranched Polycarbonates Mediates High Tumor Accumulation

Despite the numerous advantages of nanomedicines, their therapeutic efficacy is hampered by biological barriers, including fast in vivo clearance, poor tumor accumulation, inefficient penetration, and cellular uptake. Herein, cross-linked supersmall micelles based on zwitterionic hyperbranched polycarbonates can overcome these challenges for efficiently targeted drug delivery. Biodegradable acryloyl/zwitterion-functionalized hyperbranched polycarbonates are synthesized by a one-pot sequential reaction of Michael-type addition and ring-opening polymerization, followed by controlled modification with carboxybetaine thiol. Cross-linked supersmall zwitterionic micelles (X-CBMs) are readily prepared by straightforward self-assembly and UV cross-linking. X-CBMs exhibit prolonged blood circulation because of their cross-linked structure and zwitterion decoration, which resist protein corona formation and facilitate escaping RES recognition. Combined with the advantage of supersmall size (7.0 nm), X-CBMs mediate high tumor accumulation and deep penetration, which significantly enhance the targeted antitumor outcome against the 4T1 tumor model by administration of the paclitaxel (PTX) formulation (X-CBM@PTX).

Zwitterionic Biomaterials

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

Binding of Proteins to Copolymers of Varying Charges and Hydrophobicity: A Molecular Mechanism and Computational Strategies

Because of their ability to selectively bind to a target protein, copolymer nanoparticles (NPs) containing a selected combination of hydrophobic and charged groups have been frequently reported as potent antibody-like analogues. However, due to the intrinsic disorder of the copolymer NP in terms of its random monomer sequence and the cross-linked copolymer matrix, the copolymer NP is indeed strikingly different from a well-folded protein antibody and the complexation between the copolymer NP and a target protein is likely not due to a lock-key type of interaction but possibly due to a novel and unexplored molecular mechanism. Here, we study a key biomarker protein, vimentin, interacting with a set of random copolymer chains using implicit-water explicit-ion coarse-grained (CG) molecular dynamics (MD) simulations along with biolayer interferometry (BLI) analysis. Due to the charge and hydrophobicity anisotropy on the vimentin dimer (VD) surface, a set of bound copolymers are found inhomogenously adsorbed on the VD, with energetic heterogeneity for different binding sites and cooperative effect in the adsorption. Increasing the charge or hydrophobicity of the copolymer may have different consequences on the adsorption. In this study, we found that with more copolymer charges, the protein coverage increases for copolymers of low hydrophobicity and decreases of high hydrophobicity, which is explained by the distribution and size of various functional patches on the VD in loading those copolymers. Employing a coverage-dependent Langmuir model, we propose a simulation protocol to address the full profile of the copolymer binding free energy through the fit to the simulated binding isotherm. The obtained results correlate well with those from the BLI experiment, indicating the significance of this method for the rational design of the copolymer NP with engineered protein binding affinity.

Dendrimer-based drug delivery systems: history, challenges, and latest developments

Since the first dendrimer was reported in 1978 by Fritz Vögtle, dendrimer research has grown exponentially, from synthesis to application in the past four decades. The distinct structure characteristics of dendrimers include nanoscopic size, multi-functionalized surface, high branching, cavernous interior, and so on, making dendrimers themselves ideal drug delivery vehicles. This mini review article provides a brief overview of dendrimer’s history and properties and the latest developments of dendrimers as drug delivery systems. This review focuses on the latest progress in the applications of dendrimers as drug and gene carriers, including 1) active drug release strategies to dissociate drug/gene from dendrimer in response to stimuli; 2) size-adaptive and charge reversal dendrimer delivery systems that can better take advantage of the size and surface properties of dendrimer; 3) bulk and micro/nano dendrimer gel delivery systems. The recent advances in dendrimer formulations may lead to the generation of new drug and gene products and enable the development of novel combination therapies.

Recent advances on next generation of polyzwitterion-based nano-vectors for targeted drug delivery

Poly (ethylene glycol) (PEG)-based nanomedicines are perplexed by the challenges of oxidation damage, immune responses after repeated injections, and limited excretion from the body. As an alternative to PEG, bioinspired zwitterions bearing an identical number of positive and negative ions, exhibit exceptional hydrophilicity, excellent biomimetic nature and chemical malleability, endowing zwitterionic nano-vectors with biocompatibility, non-fouling feature, extended blood circulation and multifunctionality. In this review, we innovatively classify zwitterionic nano-vectors into linear, hyperbranched, crosslinked, and hybrid nanoparticles according to different chemical architectures in rational design of zwitterionic nano-vectors for enhanced drug delivery with an emphasis on zwitterionic engineering innovations as alternatives of PEG-based nanomedicines. Through combination with other nanostratagies, the intelligent zwitterionic nano-vectors can orchestrate stealth and other biological functionalities together to improve the efficacy in the whole journey of drug delivery.

Tailoring Hyperbranched Poly(β-amino ester) as a Robust and Universal Platform for Cytosolic Protein Delivery

Cytosolic protein delivery is a prerequisite for protein-based biotechnologies and therapeutics on intracellular targets. Polymers that can complex with proteins to form nano-assemblies represent one of the most important categories of materials, because of the ease of nano-fabrication, high protein loading efficiency, no need for purification, and maintenance of protein bioactivity. Stable protein encapsulation and efficient intracellular liberation are two critical yet opposite processes toward cytosolic delivery, and polymers that can resolve these two conflicting challenges are still lacking. Herein, hyperbranched poly(β-amino ester) (HPAE) with backbone-embedded phenylboronic acid (PBA) is developed to synchronize these two processes, wherein PBA enhanced protein encapsulation via nitrogen-boronate (N-B) coordination while triggered polymer degradation and protein release upon oxidation by H₂ O₂ in cancer cells. Upon optimization of the branching degree, charge density, and PBA distribution, the best-performing A2-B3-C2-S₂ -P₂ is identified, which mediates robust delivery of various native proteins/peptides with distinct molecular weights (1.6-430 kDa) and isoelectric points (4.1-10.3) into cancer cells, including enzymes, toxins, antibodies, and CRISPR-Cas9 ribonucleoproteins (RNPs). Moreover, A2-B3-C2-S₂ -P₂ mediates effective cytosolic delivery of saporin both in vitro and in vivo to provoke remarkable anti-tumor efficacy. Such a potent and universal platform holds transformative potentials for protein pharmaceuticals.

Molecular dynamics simulation insights into the cellular uptake of elastic nanoparticles through human pulmonary surfactant

The interaction between inhaled nanoparticles (NPs) and the pulmonary surfactant (PS) monolayer has drawn significant attention due to its potential in drug delivery design and application for respiratory therapeutics in active and passive cellular uptake pathways. Even though much attention has been given to explore the interaction between NPs and the PS monolayer, the effects of the NP elasticity on the translocation across the PS monolayer have not been thoroughly studied. Here, we performed a series of coarse-grained (CG) molecular dynamics simulations to study active or passive cellular uptake pathways of three NPs with different elasticities through a PS monolayer. The differences between active and passive pathways underly the enhanced targeting ability by ligand–receptor interaction (L–R interaction). In the active or passive cellular uptake pathways, it is found that the increase in stiffness level leads to a higher penetrability of NPs at the same time range. The soft NP has always been withheld inside the PS monolayer due to the lowest level of elasticity, while the other two types of NPs penetrate through the PS monolayer as the simulation progresses toward the end. The NPs in the active cellular uptake pathways take a longer time to penetrate the PS monolayer, resulting in a longer average penetration distance of approximately 40.55% and a higher average number of contacts, approximately 36.11%, than passive cellular uptake pathways, due to the L–R interaction. Moreover, it demonstrates that NPs in active cellular uptake pathways have a significantly higher targeting ability with the PS monolayer. We conclude that the level of NP elasticities has a substantial link to the penetrability in active or passive cellular uptake pathways. These results provide valuable insights into drug delivery and nanoprobe design for inhaled NPs within the lungs.

Adjusting inhaled NP elasticity affects their permeability across the human pulmonary surfactant monolayer.

Recent advances of zwitterionic based topological polymers for biomedical applications

Zwitterionic polymers, comprising hydrophilic anionic and cationic groups with the same total number of positive and negative charges on the same monomer residue, have received increasing attention due to their...

Modular amphiphilic poly(aryl ether)-based supramolecular nanomicelles: an efficient endocytic drug carrier

A rationally designed amphiphilic poly(aryl ether)-based dendrimer self-assembles into nanomicelles and exhibits tunable morphology upon varying the hydrophilic chain length. The 30 nm-sized dendrimer nanomicelles successfully entrapped Doxorubicin, demonstrated the sustained release of Doxorubicin and can successfully penetrate cancer cells through caveolae-dependent endocytosis, compared to the free drug.

Design of Polymeric Carriers for Intracellular Peptide Delivery in Oncology Applications

In recent decades, peptides, which can possess high potency, excellent selectivity, and low toxicity, have emerged as promising therapeutics for cancer applications. Combined with an improved understanding of tumor biology and immuno-oncology, peptides have demonstrated robust antitumor efficacy in preclinical tumor models. However, the translation of peptides with intracellular targets into clinical therapies has been severely hindered by limitations in their intrinsic structure, such as low systemic stability, rapid clearance, and poor membrane permeability, that impede intracellular delivery. In this Review, we summarize recent advances in polymer-mediated intracellular delivery of peptides for cancer therapy, including both therapeutic peptides and peptide antigens. We highlight strategies to engineer polymeric materials to increase peptide delivery efficiency, especially cytosolic delivery, which plays a crucial role in potentiating peptide-based therapies. Finally, we discuss future opportunities for peptides in cancer treatment, with an emphasis on the design of polymer nanocarriers for optimized peptide delivery.

Effect of Hydrophobicity and Charge Separation on the Antifouling Properties of Surface-Tethered Zwitterionic Peptides

Zwitterionic peptides emerge as a class of highly effective antifouling material in a wide range of applications such as biosensors, biomedical devices, and implants. We incorporated neutral amino acid spacers with different hydrophobicities, including serine (Ser), glycine (Gly), and leucine (Leu), into zwitterionic peptides with lysine-glutamic acid repeating units and investigated the structure and antifouling performance of the zwitterionic peptide brushes by surface plasma resonance, surface force apparatus (SFA), and all-atomistic molecular dynamics (MD) simulation techniques. Our results demonstrate that the hydrophilicity of neutral spacers alters the structure and antifouling performance of the peptide-modified surface. Hydrophilic Ser-inserted peptides reduced the interaction between the peptide monolayer and protein foulants, while hydrophobic Leu significantly increased the protein adhesion. SFA force measurements show that the presence of more spacers would increase the adhesion between the peptide monolayer and the modeling foulant lysozyme, especially for the hydrophobic spacers. MD simulations reveal that hydrophilic Ser spacers retain the hydrophilicity of the peptide monolayer and improve the antifouling performance, and Gly spacers give rise to more interchain cross-links. Leu spacers result in a more hydrophobic peptide monolayer, which leads to dehydration of the peptide monolayer and reduces the antifouling performances.

Facial Solid-Phase Synthesis of Well-Defined Zwitterionic Amphiphiles for Enhanced Anticancer Drug Delivery

Serum protein adsorption on the nanoparticle surface determines the biological identity of polymeric nanocarriers and critically impacts the in vivo stability following intravenous injection. Ultrahydrophilic surfaces are desired in delivery systems to reduce the serum protein corona formation, prolong drug pharmacokinetics, and improve the in vivo performance of nanotherapeutics. Zwitterionic polymers have been explored as alternative stealth materials for biomedical applications. In this study, we employed facial solid-phase peptide chemistry (SPPC) to synthesize multifunctional zwitterionic amphiphiles for application as a drug delivery vehicle. SPPC facilitates synthesis and purification of the well-defined dendritic amphiphiles, yielding high-purity and precise architecture. Zwitterionic glycerylphosphorylcholine (GPC) was selected as a surface moiety for the construction of a ultrahydrophilic dendron, which was coupled on solid phase to a hydrophobic dendron using multiple rhein (Rh) molecules as drug-binding moieties (DBMs) for doxorubicin (DOX) loading via pi-pi stacking and hydrogen bonding. The resulting zwitterionic amphiphilic Janus dendrimer (denoted as GPC₈-Rh₄) showed improved stabilities and sustained drug release compared to the analogue with poly(ethylene glycol) (PEG) surface (PEG^5k-Rh₄). In vivo studies in xenograft mouse tumor models demonstrated that the DOX-GPC₈-Rh₄ nanoformulation significantly improved anticancer effects compared to DOX-PEG^5k-Rh₄, owing to the improved in vivo pharmacokinetics and increased tumor accumulation.

pyPolyBuilder: Automated Preparation of Molecular Topologies and Initial Configurations for Molecular Dynamics Simulations of Arbitrary Supramolecules

The construction of a molecular topology file is a prerequisite for any classical molecular dynamics simulation. However, the generation of such a file may be very challenging at times, especially for large supramolecules. While many tools are available to provide topologies for large proteins and other biomolecules, the scientific community researching nonbiological systems is not equally well equipped. Here, we present a practical tool to generate topologies for arbitrary supramolecules: The pyPolyBuilder. In addition to linear polymer chains, it also provides the possibility to generate topologies of arbitrary, large, branched molecules, such as, e.g., dendrimers. Furthermore, it also generates reasonable starting structures for simulations of these molecules. pyPolyBuilder is a standalone command-line tool implemented in python. Therefore, it may be easily incorporated in persisting simulation pipelines on any operating systems and with different simulation engines. pyPolyBuilder is freely available on github: https://github.com/mssm-labmmol/pypolybuilder.

Antifouling Strategies of Nanoparticles for Diagnostic and Therapeutic Application: A Systematic Review of the Literature

Nanoparticles (NPs) are promising platforms for the development of diagnostic and therapeutic tools. One of the main hurdle to their medical application and translation into the clinic is the fact that they accumulate in the spleen and liver due to opsonization and scavenging by the mononuclear phagocyte system. The “protein corona” controls the fate of NPs in vivo and becomes the interface with cells, influencing their physiological response like cellular uptake and targeting efficiency. For these reasons, the surface properties play a pivotal role in fouling and antifouling behavior of particles. Therefore, surface engineering of the nanocarriers is an extremely important issue for the design of useful diagnostic and therapeutic systems. In recent decades, a huge number of studies have proposed and developed different strategies to improve antifouling features and produce NPs as safe and performing as possible. However, it is not always easy to compare the various approaches and understand their advantages and disadvantages in terms of interaction with biological systems. Here, we propose a systematic study of literature with the aim of summarizing current knowledge on promising antifouling coatings to render NPs more biocompatible and performing for diagnostic and therapeutic purposes. Thirty-nine studies from 2009 were included and investigated. Our findings have shown that two main classes of non-fouling materials (i.e., pegylated and zwitterionic) are associated with NPs and their applications are discussed here highlighting pitfalls and challenges to develop biocompatible tools for diagnostic and therapeutic uses. In conclusion, although the complexity of biofouling strategies and the field is still young, the collective data selected in this review indicate that a careful tuning of surface moieties is a pivotal step to lead NPs through their future clinical applications.

Hypoxia-degradable and long-circulating zwitterionic phosphorylcholine-based nanogel for enhanced tumor drug delivery

Tumor microenvironment has been widely utilized for advanced drug delivery in recent years, among which hypoxia-responsive drug delivery systems have become the research hotspot. Although hypoxia-responsive micelles or polymersomes have been successfully developed, a type of hypoxia-degradable nanogel has rarely been reported and the advantages of hypoxia-degradable nanogel over other kinds of degradable nanogels in tumor drug delivery remain unclear. Herein, we reported the synthesis of a novel hypoxia-responsive crosslinker and the fabrication of a hypoxia-degradable zwitterionic poly(phosphorylcholine)-based (^HPMPC) nanogel for tumor drug delivery. The obtained ^HPMPC nanogel showed ultra-long blood circulation and desirable immune compatibility, which leads to high and long-lasting accumulation in tumor tissue. Furthermore, ^HPMPC nanogel could rapidly degrade into oligomers of low molecule weight owing to the degradation of azo bond in hypoxic environment, which leads to the effective release of the loaded drug. Impressively, ^HPMPC nanogel showed superior tumor inhibition effect both in vitro and in vivo compared to the reduction-responsive phosphorylcholine-based nanogel, owing to the more complete drug release. Overall, the drug-loaded ^HPMPC nanogel exhibits a pronounced tumor inhibition effect in a humanized subcutaneous liver cancer model with negligible side effects, which showed great potential as nanocarrier for advanced tumor drug delivery.

Recent advances in development of dendritic polymer-based nanomedicines for cancer diagnosis

Dendritic polymers have highly branched three-dimensional architectures, the fourth type apart from linear, cross-linked, and branched one. They possess not only a large number of terminal functional units and interior cavities, but also a low viscosity with weak or no entanglement. These features endow them with great potential in various biomedicine applications, including drug delivery, gene therapy, tissue engineering, immunoassay and bioimaging. Most review articles related to bio-related applications of dendritic polymers focus on their drug or gene delivery, while very few of them are devoted to their function as cancer diagnosis agents, which are essential for cancer treatment. In this review, we will provide comprehensive insights into various dendritic polymer-based cancer diagnosis agents. Their classification and preparation are presented for readers to have a precise understanding of dendritic polymers. On account of physical/chemical properties of dendritic polymers and biological properties of cancer, we will suggest a few design strategies for constructing dendritic polymer-based diagnosis agents, such as active or passive targeting strategies, imaging reporters-incorporating strategies, and/or internal stimuli-responsive degradable/enhanced imaging strategies. Their recent applications in in vitro diagnosis of cancer cells or exosomes and in vivo diagnosis of primary and metastasis tumor sites with the aid of single/multiple imaging modalities will be discussed in great detail. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > in vivo Nanodiagnostics and Imaging Diagnostic Tools > in vitro Nanoparticle-Based Sensing.

Bistratal Au@Bi2S3 nanobones for excellent NIR-triggered/multimodal imaging-guided synergistic therapy for liver cancer

To fabricate a highly biocompatible nanoplatform enabling synergistic therapy and real-time imaging, novel Au@Bi₂S₃ core shell nanobones (NBs) (Au@Bi₂S₃ NBs) with Au nanorods as cores were synthesized. The combination of Au nanorods with Bi₂S₃ film made the Au@Bi₂S₃ NBs exhibit ultrahigh photothermal (PT) conversion efficiency, remarkable photoacoustic (PA) imaging and high computed tomography (CT) performance; these Au@Bi₂S₃ NBs thus are a promising nanotheranostic agent for PT/PA/CT imaging. Subsequently, poly(N-vinylpyrrolidone)-modified Au@Bi₂S₃ NBs (Au@Bi₂S₃-PVP NBs) were successfully loaded with the anticancer drug doxorubicin (DOX), and a satisfactory pH sensitive release profile was achieved, thus revealing the great potential of Au@Bi₂S₃-PVP NBs in chemotherapy as a drug carrier to deliver DOX into cancer cells. Both in vitro and in vivo investigations demonstrated that the Au@Bi₂S₃-PVP NBs possessed multiple desired features for cancer therapy, including extremely low toxicity, good biocompatibility, high drug loading ability, precise tumor targeting and effective accumulation. Highly efficient ablation of the human liver cancer cell HepG2 was achieved through Au@Bi₂S₃-PVP NB-mediated photothermal therapy (PTT). As both a contrast enhancement probe and therapeutic agent, Au@Bi₂S₃-PVP NBs provided outstanding NIR-triggered multi-modal PT/PA/CT imaging-guided PTT and effectively inhibited the growth of HepG2 liver cancer cells via synergistic chemo/PT therapy.

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Novel Au@Bi₂S₃ core shell NBs were synthesized with ultrahigh photothermal conversion efficiency (η=68.1%).

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The Au@Bi₂S₃-PVP NBs can serve as a multimodal imaging agent for PT/PA/CT imaging.

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The Au@Bi₂S₃-PVP NBs can act as nanocarrier for anticancer drug DOX in a pH sensitive DOX release profile.

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This work reports outstanding NIR-triggered trimodal PT/PA/CT imaging-guided chemo/PT synergistic therapy of liver cancer.

A nanotrap improves survival in severe sepsis by attenuating hyperinflammation

Targeting single mediators has failed to reduce the mortality of sepsis. We developed a telodendrimer (TD) nanotrap (NT) to capture various biomolecules via multivalent, hybrid and synergistic interactions. Here, we report that the immobilization of TD-NTs in size-exclusive hydrogel resins simultaneously adsorbs septic molecules, e.g. lipopolysaccharides (LPS), cytokines and damage- or pathogen-associated molecular patterns (DAMPs/PAMPs) from blood with high efficiency (92-99%). Distinct surface charges displayed on the majority of pro-inflammatory cytokines (negative) and anti-inflammatory cytokines (positive) allow for the selective capture via TD NTs with different charge moieties. The efficacy of NT therapies in murine sepsis is both time-dependent and charge-dependent. The combination of the optimized NT therapy with a moderate antibiotic treatment results in a 100% survival in severe septic mice by controlling both infection and hyperinflammation, whereas survival are only 50-60% with the individual therapies. Cytokine analysis, inflammatory gene activation and tissue histopathology strongly support the survival benefits of treatments.

Functional zwitterionic biomaterials for administration of insulin

This review summarizes the structures and biomedical applications of zwitterionic biomaterials in the administration of insulin.

Recent advances and challenges of repurposing nanoparticle-based drug delivery systems to enhance cancer immunotherapy

Cancer immunotherapy is an attractive treatment option under clinical settings. However, the major challenges of immunotherapy include limited patient response, limited tumor specificity, immune-related adverse events, and immunosuppressive tumor microenvironment. Therefore, nanoparticle (NP)-based drug delivery has been used to not only increase the efficacy of immunotherapeutic agents, but it also significantly reduces the toxicity. In particular, NP-based drug delivery systems alter the pharmacokinetic (PK) profile of encapsulated or conjugated immunotherapeutic agents to targeted cancer cells or immune cells and facilitate the delivery of multiple therapeutic combinations to targeted cells using single NPs. Recently, advanced NP-based drug delivery systems were effectively utilized in cancer immunotherapy to reduce the toxic side effects and immune-related adverse events. Repurposing these NPs as delivery systems of immunotherapeutic agents may overcome the limitations of current cancer immunotherapy. In this review, we focus on recent advances in NP-based immunotherapeutic delivery systems, such as immunogenic cell death (ICD)-inducing drugs, cytokines and adjuvants for promising cancer immunotherapy. Finally, we discuss the challenges facing current NP-based drug delivery systems that need to be addressed for successful clinical application.