Integrating Liquification of the Gelated Tumor Interstitium around Nanomedicines with Biconditional GD2-Targeting for Precise and Safe Chemotherapy.

The quick diffusion of nanomedicines in the polysaccharide-gel-filling tumor interstitium and precise active targeting are two major obstacles that have not yet been overcome. Here, a poly(L-glutamyl-L-lysine(EK) (p(EK))-camouflaged, doxorubicin (Dox)-conjugated nanomedicine is developed to demonstrate the underlying mechanism of zwitterionic shell in synchronous barrier-penetration and biconditional active targeting. The zwitterionic p(EK) shell liquifies its surrounding water molecules in the polysaccharide gel of tumor interstitium, leading to five times faster diffusion than the pegylated Doxil with similar size in tumor tissue. Its doped sulfonate groups lead to more precise active tumor-targeting than disialoganglioside (GD2) antibody by meeting the dual requirements of tumor microenvironment (TME) pH and overexpression of GD2 on tumor. Consequently, the concentrations of the nanomedicine in tumor are always higher than in life-supported organs in whole accumulation process, reaching over ten times higher Dox in GD2-overexpressing MCF-7 tumors than in life-supporting organs. Furthermore, the nanomedicine also avoids anti-GD2-like accumulation in GD2-expressing kidney in a mouse model. Thus, the nanomedicine expands the therapeutic window of Doxil by more than three times and eliminates tumors with negligible myocardial and acute toxicity. This new insight paves an avenue to design nanodelivery systems for highly precise and safe chemotherapy.

Spontaneously Restoring Specific Bioaffinity of RGD in Linear RGD-containing Peptides by Conjugation with Zwitterionic Dendrimers.

Peptides are more versatile than small molecule drugs, but their specific bioaffinities are usually lower than their original native proteins because of the loss of preferred conformations. To overcome this key obstacle, we demonstrated a hydrogen bond-induced conformational constraint method to enhance the specific bioaffinities of peptides to achieve a high success rate by using linear RGD-containing peptides as a model of bioactive peptides. By performing molecular simulation, we found that the chemically immobilized linear CRGDS via cysteine (C) at the N-terminus on zwitterionic PAMAM G-5 can not only spontaneously restore the natural conformation of the RGD segment through the assistance of the dynamic hydrogen bond from serine (S) at the C-terminus of the peptide, but it can also narrow the distribution of all possible conformations. Consequently, the conjugates showed comparable or even better high affinity than native proteins without the use of conventional, labor-intensive, synthesis-based structure search methods to construct a binding conformation. In addition, the conjugates showed globular protein-like characteristics chemically, physically, and physiologically. They exhibited not only high efficacy and biosafety both in vitro and in vivo, but they also showed extremely high thermostability even upon boiling in a solution. This approach offers great design flexibility for reviving functional peptides without impairing their high specific affinity for their targets. STATEMENT OF SIGNIFICANCE: In this work, we developed a swift approach to spontaneously restore the natural conformation of a linear peptide from a nature protein and thus enhance its specific bioaffinity instead of constructing a binding conformation by the labor-intensive, synthesis-based structure search method. In details, our new approach involves dynamically constraining the linear peptide on a zwitterionic PAMAM G-5 surface by a combination of chemical bonding at one terminus and dynamic hydrogen bonding at the other terminus of the linear peptide. The zwitterionic background offers abundant interaction sites for hydrogen bonding as well as resistance to nonspecific interactions. This approach fully restores the specific bioaffinity of RGD segments on a zwitterionic PAMAM G-5 through only one conjugation point at the C-terminus of the peptide. Moreover, the bioaffinity of all three types of RGD-containing peptides is successfully restored, which indicates the high rate of success of this approach in affinity restoring.

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. Results showed that the hydrogel crosslinked by only 2 mg/mL mGOa nano chemical crosslinker in the poly(2-hydroxyethyl methacrylate-co-acrylamide) hydrogel (molar ratio: 1:1) can effectively enhance the mechanical strength up to 14.1 ± 2.1 MPa at a high compressive strain (90.6%) with an elastic modulus of less than 0.03 MPa at the initial 5% compression, whereas the hydrogel crosslinked by methacrylated single-layer graphene oxide (sGOa) or a small-molecule chemical crosslinker, N,N'-methylene bisacrylamide, can only reach 2.3 ± 0.8 MPa and 1.4 ± 0.4 MPa, respectively. In addition, the instantaneous modulus of the mGOa crosslinked hydrogel rapidly increased to the peak value with the increase of strain. The repeated compression test of HcA-mGOa hydrogels showed the responsive increase of the modulus, which was promoted by the synergism of polymer chains under compression. This indicated that the interlayer sliding of mGOa is the key contributor to mechanical strength enhancement, which provides a new rationale to design tough hydrogels.

Development of Nonfouling Zwitterionic Copolymerized Peptides Based on Glutamic Acid and Lysine Dimers for Adjustable Enzymatic Degradation.

Nonspecific protein adsorption-resistant materials, the so-called nonfouling materials, are crucial biomaterials in biomedical applications. Up-to-date, little attention was paid to the biodegradability of these materials. In this work, nonfouling zwitterionic copolymerized peptides composed of the N-l-glumatyl-l-lysine dimer (EK) and δ-l-lysinyl-l-glutamic acid dimer (E-K, glutamic acid with the lysine side chain) at various ratios were synthesized to investigate the enzymatic degradation rate. Two types of proteases (trypsin and alkaline protease), which represent a site-specific and less site-specific cleavage protease, respectively, were used to demonstrate the adjustable degradability by tracking the molecular weight (Mw) at different digestion times. Results showed that higher compositions of the E-K dimer lead to slower degradation rates by both proteases and larger fragments after 120 min digestion. With the composition of the E-K dimer over 50%, the degradation of copolymerized peptides by both proteases becomes very slow. This indicated that the bulky lysinyl side chain on E-K can alter the enzymolysis process for adjusting the enzymatic degradability of the newly synthesized zwitterionic copolymerized peptides, which could be promising candidates for biomedical applications in vivo.

Resistance to Long-Term Bacterial Biofilm Formation Based on Hydrolysis-Induced Zwitterion Material with Biodegradable and Self-Healing Properties.

Long-term resistance of biomaterials to the bacterial biofilm formation without antibiotic or biocide is highly demanded for biomedical applications. In this work, a novel biodegradable biomaterial with excellent capability to prevent long-term bacterial biofilm formation is prepared by the following two steps. Ethylcarboxybetaine ester analogue methacrylate (ECBEMA), poly(ethylene glycol) monomethacrylate (PEGMA), and 3-methacryloxypropyletris(trimethylsiloxy)silane (TRIS) were copolymerized to obtain p(ECBEMA-PEGMA-TRIS) (PEPT). Then, PEPT was cross-linked by isocyanate-terminated polylactic acid (IPDI-PLA-IPDI) to obtain the final PEPTx-PLAy (x and y are the number-average molecular weights (Mn) of PEPT and PLA, respectively) with optimal mechanical strength and adjustable surface regeneration rate. Static contact angle measurement, protein adsorption measurement, and attenuated total reflectance infrared (ATR-IR) results show that the PEPT19800-PLA800 film surface can generate a zwitterionic layer to resist nonspecific protein adsorption after surface hydrolysis. Quartz crystal microbalance with dissipation (QCM-D) results indicates that the PEPT19800-PLA800 film can undergo gradual degradation of the surface layer at the lowest swelling rate. Particularly, this material can efficiently resist the bacterial biofilm formation of both Gram-positive bacteria and Gram-negative bacteria over 14 and 6 days, respectively. Moreover, the material also shows an ideal self-healing feature to adapt to harsh conditions. Thus, this nonfouling material shows great potential in biomedical applications and marine antifouling coatings without antibiotic or biocide.

An electrospun polyurethane scaffold-reinforced zwitterionic hydrogel as a biocompatible device.

Although zwitterionic hydrogels exhibit excellent hemocompatibility, their extremely low tensile strength is an obstacle for their use in blood-contacting devices. Electrospun fiber scaffold-reinforced zwitterionic hydrogels are a possible solution to overcome the challenges of both mechanical strength and hemocompatibility. In this work, electrospun polyurethane (ePU) fiber scaffold-reinforced sulfobetaine methacrylate (SBMA) hydrogels (SRgels) were prepared. The SRgels exhibited 4.7 ± 0.5 MPa tensile fracture stress, while the interpenetration between the hydrogel and the fiber scaffold remained intact even under 2.8 MPa tensile stress at 3.0 mm mm-1 strain load; this confirms that the SRgels maintain excellent hemocompatibility for both blood cell adhesion and fibrinogen adsorption under physiological dynamic loading and that dynamically structural matching is achieved between the scaffold and the zwitterionic hydrogels. Mechano-induced self-enhancement was also observed after preloading more than 2.0 mm mm-1 tensile strain to resist fracture. In short, the preparation of SRgels can enable zwitterionic hydrogels to meet the requirement for mechanical strength in bio-applications as blood-contacting devices.

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. The pH-induced disintegration and enzyme-induced degradation of the nanoformulation were confirmed by dynamic light scattering and gel permeation chromatography. Efficient internalization of DOX in the cells and high antitumor activity in vitro was observed. Compared with the free drug, this nanoformulation showed higher accumulation in tumor and lower systemic toxicity in vivo. The DOX-loaded zwitterionic RGD-conjugated polypeptide vesicles show potential application for targeted drug delivery in the clinic.

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. Hydrogels loaded with two model drugs, doxorubicin hydrochloride (DOX·HCl) (positively charged anti-cancer drug) and diclofenac sodium (negatively charged anti-inflammatory drug), showed accelerated complete drug release and full enzymatic degradation in the presence of trypsin, which was reported to be expressed in various carcinomas and inflammations. The drug release also responds to the pH change through tuning charge-charge interaction. These indicated that the prepared hydrogels were promising candidates for drug delivery systems.

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. The doxorubicin (DOX) loaded PALLZ micelles showed excellent resistance to nonspecific protein adsorption in FBS, which leads to very low internalization. Moreover, PALLZ micelles showed no cytotoxicity to MCF7, HeLa and HepG-2 cells up to 500 µg mL-1. All these results indicated that zwitterionic amphiphilic block polypeptides could be promising materials for NDVs.

[A case of Keutel syndrome in child (review the literature)].

OBJECTIVE: The purpose is to report a calcification of the cartilaginous of the tracheobronchial case in child, and to recognize the clinical and imaging features on Keutel syndrome. METHOD: A comprehensive analysis of the clinical data and X-ray,CT. Some literatures involving some symptoms of this child were reviewed. RESULT: This patient diagnosed with Keutel syndrome finally. CONCLUSION: When we meet calcification of the cartilaginous of the tracheobronchial patient in clinic, it may be Keutel syndrome.