Extracellular vesicles incorporating retrovirus-like capsids for the enhanced packaging and systemic delivery of mRNA into neurons.

The blood-brain barrier (BBB) restricts the systemic delivery of messenger RNAs (mRNAs) into diseased neurons. Although leucocyte-derived extracellular vesicles (EVs) can cross the BBB at inflammatory sites, it is difficult to efficiently load long mRNAs into the EVs and to enhance their neuronal uptake. Here we show that the packaging of mRNA into leucocyte-derived EVs and the endocytosis of the EVs by neurons can be enhanced by engineering leucocytes to produce EVs that incorporate retrovirus-like mRNA-packaging capsids.

Minimizing the off-target frequency of the CRISPR/Cas9 system zwitterionic polymer conjugation and peptide fusion.

The clustered, regularly interspaced, short palindromic repeats (CRISPR)-associated protein 9 (Cas9) system is a powerful genome-editing tool that is widely used in many different applications. However, the high-frequency mutations induced by RNA-guided Cas9 at sites other than the intended on-target sites are a major concern that impedes therapeutic and clinical applications. A deeper analysis shows that most off-target events result from the non-specific mismatch between single guide RNA (sgRNA) and target DNA.

Hidden hydrophobicity impacts polymer immunogenicity.

Antibodies against poly(ethylene glycol) (PEG) have been found to be the culprit of side reactions and efficacy loss of a number of PEGylated drugs. Fundamental mechanisms of PEG immunogenicity and design principles for PEG alternatives still have not been fully explored. By using hydrophobic interaction chromatography (HIC) under varied salt conditions, we reveal the "hidden" hydrophobicity of those polymers which are generally considered as hydrophilic.

Mitigating the Immunogenicity of AAV-Mediated Gene Therapy with an Immunosuppressive Phosphoserine-Containing Zwitterionic Peptide.

Although recombinant adeno-associated viruses (AAVs) are considered low immunogenic and safe for gene delivery, the immunogenicity of capsids still represents a major obstacle to the readministration of AAV vectors. Here, we design an immunosuppressive zwitterionic phosphoserine (PS)-containing polypeptide to induce AAV-specific immune tolerance and eradicate the immunological response. AAVs modified with the zwitterionic PS polypeptide maintain their transduction activity and tissue tropism but suppress the induction of AAV-specific antibodies.

Phosphatidylserine Lipid Nanoparticles Promote Systemic RNA Delivery to Secondary Lymphoid Organs.

Secondary lymphoid organs (SLOs) are an important target for mRNA delivery in various applications. While the current delivery method relies on the drainage of nanoparticles to lymph nodes by intramuscular (IM) or subcutaneous (SC) injections, an efficient mRNA delivery carrier for SLOs-targeting delivery by systemic administration (IV) is highly desirable but yet to be available. In this study, we developed an efficient SLOs-targeting carrier using phosphatidylserine (PS), a well-known signaling molecule that promotes the endocytic activity of phagocytes and cellular entry of enveloped viruses.

3D Interlayer Slidable Multilayer Nano-Graphene Oxide Acrylate Crosslinked Tough Hydrogel.

The design of three-dimensional crosslinked units with a spatial structure is of great significance for improving the mechanical properties of hydrogels. However, almost all the nanocomposites incorporated in hydrogels were defined as rigid nanofillers without further discussion on the potential contribution from the spatial structure change. In this work, the 3D nano chemical crosslinker multilayer graphene oxide acrylate (mGOa) was developed as a pressure-responsive crosslinker to achieve both low elastic modulus and high compression stress by synergizing more polymer chains against the loading force through interlayer sliding.

High-Strength and Nonfouling Zwitterionic Triple-Network Hydrogel in Saline Environments.

Zwitterionic hydrogels have received great attention due to their excellent nonfouling and biocompatible properties, but they suffer from weak mechanical strength in the saline environments important for biomedical and engineering applications due to the "anti-polyelectrolyte" effect. Conventional strategies to introduce hydrophobic or non-zwitterionic components to increase mechanical strength compromise their nonfouling properties. Here, a highly effective strategy is reported to achieve both high mechanical strength and excellent nonfouling properties by constructing a pure zwitterionic triple-network (ZTN) hydrogel.

Zwitterionic Peptide Cloak Mimics Protein Surfaces for Protein Protection.

Inspired by the amino acid composition of natural protein surfaces, we developed a zwitterionic cloak containing multi-layers of short alternating glutamic acid and lysine (EK) peptides as a facile, highly effective and low-immunogenicity approach for the protection and delivery of biotherapeutics. Each EK layer grafted to proteins provides multiple times of new lysine reaction sites for the growth of subsequent EK layers. This unique design allows EK peptides to achieve high coating density on proteins, overcoming the limitation of traditional conjugation strategies that rely on the number of innate lysine groups.

De novo design of functional zwitterionic biomimetic material for immunomodulation.

Superhydrophilic zwitterionic polymers are a class of nonfouling materials capable of effectively resisting any nonspecific interactions with biological systems. We designed here a functional zwitterionic polymer that achieves a trade-off between nonspecific interactions providing the nonfouling property and a specific interaction for bioactive functionality. Built from phosphoserine, an immune-signaling molecule in nature, this zwitterionic polymer exhibits both nonfouling and immunomodulatory properties.

Zwitterionic Polymer Conjugated Glucagon-like Peptide-1 for Prolonged Glycemic Control.

Glucagon-like peptide-1 (GLP-1) is of particular interest for treating type 2 diabetes mellitus (T2DM), as it induces insulin secretion in a glucose-dependent fashion and has the potential to facilitate weight control. However, native GLP-1 is a short incretin peptide that is susceptible to fast proteolytic inactivation and rapid clearance from the circulation. Various GLP-1 analogs and bioconjugation of GLP-1 analogs have been developed to counter these issues, but these modifications are frequently accompanied by the sacrifice of potency and the induction of immunogenicity.

Zwitterionic Nanoconjugate Enables Safe and Efficient Lymphatic Drug Delivery.

The lymphatic system provides a major route for the dissemination of many diseases such as tumor metastasis and virus infection. At present, treating these diseases remains a knotty task due to the difficulty of delivering sufficient drugs into lymphatics. After subcutaneous (SC) injection, the transferring of drugs to lymphatic vessels is significantly attenuated by physiological barriers in the interstitial space.

Enhanced pulmonary systemic delivery of protein drugs via zwitterionic polymer conjugation.

Pulmonary delivery of protein drugs into the systemic circulation is highly desirable as the lung provides a large absorption surface area and a more favorable environment for biologics compared to other delivery routes. However, pulmonary systemic delivery of proteins presents several challenges such as poor protein stability and limited bioavailability, especially for large proteins (molecular weight > 50 kDa), which exhibit an average bioavailability of 1% to 5% when delivered via the pulmonary route. Here, we demonstrated that with the conjugation of zwitterionic poly(carboxybetaine) (pCB) polymer, the bioavailability of organophosphate hydrolase (OPH) was significantly increased from 5% to 53%.

Elucidating Molecular Design Principles for Charge-Alternating Peptides.

The therapeutic potential of protein drugs has been hindered by difficulties with long-term stability and rapid clearance from the body. Recombinant fusion proteins provide a scalable platform for engineered biologics, whereby a polypeptide domain is appended to alter the physical characteristics of a therapeutic protein and enhance its pharmaceutical viability. Two simple design principles for recombinant fusion proteins, based on the physical properties of the polypeptide domain, have been separately applied to address issues with the stability and delivery of biologics.

Trimethylamine -oxide-derived zwitterionic polymers: A new class of ultralow fouling bioinspired materials.

Materials that resist nonspecific protein adsorption are needed for many applications. However, few are able to achieve ultralow fouling in complex biological milieu. Zwitterionic polymers emerge as a class of highly effective ultralow fouling materials due to their superhydrophilicity, outperforming other hydrophilic materials such as poly(ethylene glycol).

Nanoscavenger provides long-term prophylactic protection against nerve agents in rodents.

Nerve agents are a class of organophosphorus compounds (OPs) that blocks communication between nerves and organs. Because of their acute neurotoxicity, it is extremely difficult to rescue the victims after exposure. Numerous efforts have been devoted to search for an effective prophylactic nerve agent bioscavenger to prevent the deleterious effects of these compounds.

Zwitterlation mitigates protein bioactivity loss over PEGylation.

Conjugation with poly(ethylene glycol) (PEG) or PEGylation is a widely used tool to overcome the shortcomings of native proteins, such as poor stability, inadequate pharmacokinetic (PK) profiles, and immunogenicity. However, PEGylation is often accompanied by an unwanted detrimental effect on bioactivity, particularly, resulting from the amphiphilic nature of PEG. This is especially true for PEGylated proteins with large binding targets.

A Chromatin-Mimetic Nanomedicine for Therapeutic Tolerance Induction.

The undesirable immune response poses a life-threatening challenge to human health. It not only deteriorates the therapeutic performance of biologic drugs but also contributes to various diseases such as allergies and autoimmune diseases. Inspired by the role of chromatin in the maintenance of natural immune tolerance, here we report a DNA-protein polymeric nanocomplex that can mimic the tolerogenic function of chromatin and induce an immune tolerance to its protein cargos.

Ultralow Fouling and Functionalizable Surface Chemistry Based on Zwitterionic Carboxybetaine Random Copolymers.

Here, we report a simple yet effective surface-modification approach to imparting hydrophobic surfaces with superhydrophilicity using ultralow fouling/functionalizable carboxybetaine (CB) copolymers via a dip-coating technique. A new series of CB random copolymers with varying amphiphilicities were synthesized and coated on hydrophobic polypropylene (PP) and polystyrene (PS) surfaces. The nonfouling capability of each coating was screened by an enzyme-linked immunosorbent assay (ELISA) and further comprehensively assessed against 100% human serum by a Micro BCA protein assay kit.

Revealing the Immunogenic Risk of Polymers.

Poly(ethylene glycol) (PEG) conjugation has been the gold standard to ameliorate the pharmacokinetic (PK) and immunological profiles of proteins. PEG polymer does become immunogenic once attached to proteins, evoking PEG-specific antibody (Ab) responses. The anti-PEG Abs could cause PEGylated biologic treatments to fail and even result in lethal adverse reactions.

Development of Zwitterionic Polypeptide Nanoformulation with High Doxorubicin Loading Content for Targeted Drug Delivery.

Much attention has been drawn to targeted nanodrug delivery systems due to their high therapeutic efficacy in cancer treatment. In this work, doxorubicin (DOX) was incorporated into a zwitterionic arginyl-glycyl-aspartic acid (RGD)-conjugated polypeptide by an emulsion solvent evaporation technique with high drug loading content (45%) and high drug loading efficiency (95%). This zwitterionic nanoformulation showed excellent colloidal stability at high dilution and in serum.

Polypeptides with High Zwitterion Density for Safe and Effective Therapeutics.

The commonly used "stealth material" poly(ethylene glycol) (PEG) effectively promotes the pharmacokinetics of therapeutic cargos while reducing their immune response. However, recent studies have suggested that PEG could induce adverse reactions, including the emergence of anti-PEG antibodies and tissue histologic changes. An alternative stealth material with no or less immunogenicity and organ toxicity is thus urgently needed.

Zwitterionic Nanocages Overcome the Efficacy Loss of Biologic Drugs.

For biotherapeutics that require multiple administrations to fully cure diseases, the induction of undesirable immune response is one common cause for the failure of their treatment. Covalent binding of hydrophilic polymers to proteins is commonly employed to mitigate potential immune responses. However, while this technique is proved to partially reduce the antibodies (Abs) reactive to proteins, it may induce Abs toward their associated polymers and thus result in the loss of efficacy.

Mitigation of Inflammatory Immune Responses with Hydrophilic Nanoparticles.

While hydrophobic nanoparticles (NPs) have been long recognized to boost the immune activation, whether hydrophilic NPs modulate an immune system challenged by immune stimulators and how their hydrophilic properties may affect the immune response is still unclear. To answer this question, three polymers, poly(ethylene glycol) (PEG), poly(sulfobetaine) (PSB) and poly(carboxybetaine) (PCB), which are commonly considered hydrophilic, are studied in this work. For comparison, nanogels with uniform size and homogeneous surface functionalities were made from these polymers.

Development of ionic strength/pH/enzyme triple-responsive zwitterionic hydrogel of the mixed l-glutamic acid and l-lysine polypeptide for site-specific drug delivery.

Environmentally responsive hydrogels show enormous potential in various applications, such as tissue engineering and drug delivery. The site-specific controlled drug delivery of hydrogels can improve the therapeutic outcome and minimize the negative side effects. In this work, enzymatically digestible hydrogels, which are composed of equally mixed l-glutamic acid (E) and l-lysine (K) polypeptides after being crosslinked by the coupling reaction between carboxyl groups and primary amines catalyzed by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide·HCl (EDC·HCl), were prepared to improve the biocompatibility through reducing the nonspecific protein adsorption and cell attachment.

Development of polypeptide-based zwitterionic amphiphilic micelles for nanodrug delivery.

Protein molecules, which typically have a hydrophobic core and a zwitterionic shell with a polypeptide backbone, could be ideal materials for nanodrug vehicles (NDVs) with low side effects. Here, we synthesized poly(l-aspartic acid(lysine))-b-poly(l-lysine(Z)) (PAsp(Lys)-b-PLys(Z)) (PALLZ), a novel amphiphilic block polypeptide with key structures of protein to investigate the possibility for use as a NDV. This polypeptide can spontaneously self-assemble into micelles in aqueous solution with a zwitterionic brush (the PAsp(Lys) part) to provide the nonfouling shell and a hydrophobic core (the PLys(Z) part) for loading hydrophobic drugs.