Facile Synthesis of Glycopolypeptides by Combination of Ring-Opening Polymerization of an Alkyne-Substituted N -carboxyanhydride and Click “Glycosylation”

Polytyrosine-Coated Paper Electrode for Sensitive and Selective Sensing of NADH

Reduced nicotinamide adenine dinucleotide (NADH)-detecting electrochemical sensors are attractive in monitoring and diagnosing various physiological disorders of NADH abnormalities. The NADH detection methods using conventional electrodes are challenging due to slow electron transfer and fouling effect. Interestingly, paper-based flexible and disposable electrodes (PE) are superior for sensing biomolecules through simple detection procedures with excellent sensitivity and selectivity. Herein, to construct a conducting polypeptide-modified paper electrode, initially, polytyrosine (PTyr) is synthesized from l-tyrosine N-carboxy anhydride through ring-opening polymerization, and PTyr is drop-coated on the PE. The PTyr-modified paper electrode (PMPE) demonstrated excellent electrochemical properties and facilitated the electrooxidation of NADH at a lower potential of 576 mV. The PMPE displayed a linear detection between 25 and 145 μM of NADH concentration, with a lower detection limit of 0.340 μM. Under ideal circumstances, the sensor developed displayed an excellent NADH detection capability without interference with the most common electroactive species, ascorbic acid. The PMPE facilitates good electrocatalytic activity toward NADH, which can also be employed as a substrate material for biofuel cells.

Recent advances in post-polymerization modifications on polypeptides: synthesis and applications

Polypeptides, a kind of very promising biomaterial, have shown a wide range of applications due to their excellent biocompatibility, easy accessibility, and structural variability. To synthesize polypeptides with desired functions, post-polymerization modification (PPM) plays an important role in introducing novel chemical structure on their side-chains. The key of PPM strategy is to develop highly selective and efficient reactions that can couple the additional functional moieties with pre-installed side-chain functionalities on polypeptides. In this minireview, classic PPM reactions and especially their recent progresses are summarized, including different modification approaches for unsaturated alkyl group, oxygen-containing functional group, nitrogen-containing functional group, sulfur-containing functional group and other special functional group on side chains. In addition, this review also highlights the applications of structure-diversified polypeptides generated via PPM strategy in the field of biomaterial.

Crucial Impact of Residue Chirality on the Gelation Process and Biodegradability of Thermoresponsive Polypeptide Hydrogels

Thermosensitive polypeptide hydrogels have gained considerable attention in potential biomedical applications, of which the polymer structure may be tuned by residue chirality. In this study, polypeptide-based block copolymers with different chiralities were synthesized by ring-opening polymerization of γ-ethyl-l-glutamate N-carboxyanhydride and/or γ-ethyl-d-glutamate N-carboxyanhydride using amino-terminated monomethoxy poly(ethylene glycol) as a macroinitiator. All mPEG-polypeptide copolymers underwent sol-gel transition with an increase in temperature. The block copolymers with mixed enantiomeric residues of γ-ethyl-l-glutamate (ELG) and γ-ethyl-d-glutamate (EDG) in the polypeptide blocks exhibited lower critical gelation concentrations and lower critical gelation temperatures compared with those composed of pure ELG or EDG residues. We established that the difference in gelation properties between the copolymers was derived from the distinction of the secondary structures. We further demonstrated the influence of polypeptide chirality on the degradability and biocompatibility of hydrogels in vivo. Our findings provide insights into the design of hydrogels having tailored secondary conformation, gelation property, and biodegradability.

Synthetic linear glycopolymers and their biological applications

As typical affinities of carbohydrates with their receptors are modest, polymers of carbohydrates (glycopolymers) are exciting tools to probe the multifaceted biological activities of glycans. In this review, the linear glycopolymers and the multivalency effects are first introduced. This is followed by discussions of methods to synthesize these polymers. Subsequently, the interactions of glycopolymers with plant lectins and viral/bacterial carbohydrate binding proteins are discussed. In addition, applications of the glycopolymers in facilitating glycan microarray studies, mimicking cell surface glycans, modulation of the immune system, cryoprotection of protein, and electron-beam lithography are presented to stimulate further development of this fascinating technology.

Design, synthesis and biological applications of glycopolypeptides

Carbohydrates play essential structural and biochemical roles in all living organisms. Glycopolymers are attractive as well-defined biomimetic analogs to study carbohydrate-dependent processes, and are widely applicable biocompatible materials in their own right. Glycopolypeptides have shown great promise in this area since they are closer structural mimics of natural glycoproteins than other synthetic glycopolymers and can serve as carriers for biologically active carbohydrates. This review highlights advances in the area of design and synthesis of such materials, and their biomedical applications in therapeutic delivery, tissue engineering, and beyond.

Reduction-responsive sulfur dioxide polymer prodrug nanoparticles loaded with irinotecan for combination osteosarcoma therapy

Combination therapy can boost the therapeutic effectiveness of monotherapies by achieving synergy between therapeutic agents. Herein, a reduction-responsive sulfur dioxide (SO₂) polymer prodrug was synthesized as a nanocarrier to load irinotecan (IRN) to be used in combination osteosarcoma therapy. The SO₂ prodrug (denoted as mPEG-PLG (DNs)) was synthesized by coupling a small-molecule SO₂ donor, N-(3-azidopropyl)-2,4-dinitrobenzenesulfonamide (AP-DNs), to the side chains of methoxy poly (ethylene glycol)-block-poly (γ-propargyl-_L-glutamate) block copolymer. The mPEG-PLG (DNs) had the ability to self-assemble into micelles while simultaneously encapsulating IRN in aqueous media. The formed micelles led to enhanced SO₂ and IRN release in reductive conditions. Using nile red as a model drug, the loaded micelles were efficiently internalized by cancer cells, demonstrated by confocal laser scanning microscopy and flow cytometry. The release of SO₂ within nanoparticles (NPs) in tumor cells led to enhanced intracellular reactive oxygen species amounts together with induced oxidative destruction to cancer cells. Furthermore, the IRN-loaded SO₂ polymer prodrug NPs mediated synergistic therapeutic effects against osteosarcoma cells, leading to improved biodistribution and enhanced tumor growth inhibition over control groups in a murine osteosarcoma model. Taken together, this work highlights the potential of SO₂ polymer prodrugs as reduction-responsive nanocarriers to load chemotherapeutics for effective combination osteosarcoma therapy.

Using Polypeptide Bearing Furan Side Chains as a General Platform to Achieve Highly Effective Preparation of Smart Glycopolypeptide Analogue-Based Nano-Prodrugs for Cancer Treatment

Although several synthetic polypeptide-based nano-prodrugs (NPDs) have entered clinical trials for cancer treatment, achieving a highly effective production of the NPDs for clinical translation remains a challenge. Herein, we develop a typical preparation of pH/glutathione (GSH) dual-responsive glycopolypeptide analogue NPDs having a high drug capsulation/loading efficiency of ca. 93% and ca. 27% even based on ring-opening polymerization (ROP) of a novel and general furan-containing N-carboxyanhydride (NCA) monomer, which facilitates the Diels-Alder (D-A) side-chain functionalization by maleimide modified chemotherapy drug without using any reactive additives. High reactivity of the D-A reaction resulting in the high preparation efficiency of the NPDs is confirmed by ¹H NMR and density functional theory (DFT) calculations. The self-assembled properties as well as the dual-responsiveness of the NPDs are systemically studied by particle size and zeta potential assay, transmission electron microscopy and drug-delivery dynamics. The cell uptake mechanism, intracellular drug distribution, in vitro/vivo antitumor activity evaluations and the main organ damages of the NPDs are all investigated. Our work can provide a good solution to solve the inefficient fabrication of the smart synthetic polypeptide-based micelles for cancer treatment by following this general and sophisticated platform.

Functional Glycopolypeptides: Synthesis and Biomedical Applications

Employing natural-based renewable sugar and saccharide resources to construct functional biopolymer mimics is a promising research frontier for green chemistry and sustainable biotechnology. As the mimics/analogues of natural glycoproteins, synthetic glycopolypeptides attracted great attention in the field of biomaterials and nanobiotechnology. This review describes the synthetic strategies and methods of glycopolypeptides and their analogues, the functional self-assemblies of the synthesized glycopolypeptides, and their biological applications such as biomolecular recognition, drug/gene delivery, and cell adhesion and targeting, as well as cell culture and tissue engineering. Future outlook of the synthetic glycopolypeptides was also discussed.

Helical polymers for biological and medical applications

Helices are the most prevalent secondary structure in biomolecules and play vital roles in their activity. Chemists have been fascinated with mimicking this molecular conformation with synthetic materials. Research has now been devoted to the synthesis and characterization of helical materials, and to understand the design principles behind this molecular architecture. In parallel, work has been done to develop synthetic polymers for biological and medical applications. We now have access to materials with controlled size, molecular conformation, multivalency or functionality. As a result, synthetic polymers are being investigated in areas such as drug and gene delivery, tissue engineering, imaging and sensing, or as polymer therapeutics. Here, we provide a critical view of where these two fields, helical polymers and polymers for biological and medical applications, overlap. We have selected relevant polymer families and examples to illustrate the range of applications that can be targeted and the impact of the helical conformation on the performance. For each family of polymers, we briefly describe how they can be prepared, what helical conformations are observed and what parameters control helicity. We close this Review with an outlook of the challenges ahead, including the characterization of helicity through the process and the identification of biocompatibility.

Hypoxia-Responsive Polypeptide Nanoparticles Loaded with Doxorubicin for Breast Cancer Therapy

Microenvironments of various solid tumors are characterized by hypoxia. Herein, we report a novel nanoparticle that can selectively release loaded drugs in hypoxic environments. The nanoparticle was prepared using a hypoxia-responsive amphiphilic polymer in aqueous media. The polymer was synthesized by conjugating a hydrophobic small molecule, 4-nitrobenzyl (3-azidopropyl) carbamate, to the side chains of an mPEG-PPLG copolymer. Doxorubicin (DOX) could be loaded into the nanoparticles with a high efficiency of 97.8%. The generated drug-loaded micellar nanoparticles (PPGN@DOX) presented hypoxia-sensitive drug release behavior in vitro. Meanwhile, PPGN@DOX could be effectively internalized by 4T1 cells and could release DOX into the cell nuclei under hypoxic conditions. The in vitro anticancer results suggested that PPGN@DOX presented superior tumor cell-killing ability compared with free DOX in hypoxic environments. Furthermore, PPGN@DOX prolonged the blood circulation time and improved the biological distribution of DOX, resulting in increased antitumor outcomes and reduced side effects in vivo. Overall, the present work demonstrates that hypoxia-responsive nanoparticles have great application potential in the treatment of hypoxic tumors.

Dual stimuli-responsive polypeptide prepared by thiol-ene click reaction of poly(l-cysteine) and N, N-dimethylaminoethyl acrylate

Stimuli-responsive polymers that can undergo conformational changes with external triggers have enabled themselves as smart materials for various utilizations, among which biodegradability is of particular importance to be engineered for biomedical application. In this study, a thermo and pH dual responsive polypeptide (N, N-dimethylaminoethyl acrylate-modified poly(l-cysteine)) (PLC-g-DMAEA) was prepared by the combination of N-carboxyanhydride ring-open polymerization and thiol-ene click chemistry. The biodegradable poly(l-cysteine) (PLC) with pendant thiol groups provided an easily clickable backbone for postmodification, which was demonstrated by reacting with a well-known monomer of N, N-dimethylaminoethyl acrylate (DMAEA) to achieve both temperature and pH responsiveness. The irreversible thermo-response of PLC-g-DMAEA could be attributed to the ordered β-sheets formed upon heating, leading to the trapped side groups with poor water accessibility. Moreover, this copolymer precipitated at pH ranging from 7.5 to 9.7, but protonation of tertiary amine groups (pH < 7.5) and salt forming of masked thiol groups (pH > 9.7) rendered it soluble in water. Our results revealed that a ready available vinyl monomer could be easily clicked onto the biodegradable PLC and its stimuli responsiveness would be reserved. Moreover, the primary and secondary structures of PLC might influence the conformation, thus leading to the unique responsive behavior of the resulted copolymer.

Functional biodegradable polymers via ring-opening polymerization of monomers without protective groups

Biodegradable polymers are of current interest and chemical functionality in such materials is often demanded in advanced biomedical applications. Functional groups often are not tolerated in the polymerization process of ring-opening polymerization (ROP) and therefore protective groups need to be applied. Advantageously, several orthogonally reactive functions are available, which do not demand protection during ROP. We give an insight into available, orthogonally reactive cyclic monomers and the corresponding functional synthetic and biodegradable polymers, obtained from ROP. Functionalities in the monomer are reviewed, which are tolerated by ROP without further protection and allow further post-modification of the corresponding chemically functional polymers after polymerization. Synthetic concepts to these monomers are summarized in detail, preferably using precursor molecules. Post-modification strategies for the reported functionalities are presented and selected applications highlighted.

Biologically Active Branched Polysaccharide Mimetics: Synthesis via Ring-Opening Polymerization of a Maltose-Based β-Lactam

Stereoregular poly-amido-saccharides bearing α-glucopyranose branches (Mal-PASs) are synthesized by anionic ring-opening polymerization of a maltose-based β-lactam monomer followed by debenzylation. The polymerization affords high molecular weight polymers (up to 31500 g/mol) with narrow dispersities (Đ < 1.1). Deprotected Mal-PASs are highly soluble in water and adopt a left-handed helical conformation in solution. Turbidimetric assay shows that Mal-PASs are multivalent ligands to lectin Concanavalin A.

Pyrene-Terminated, Amphiphilic Polypeptide and Its Hydrogen-Bonded Interpolymer Complex as Delivery Systems of Doxorubicin

The intensity ratio between the first (373 nm) and the third (383 nm) vibronic peaks [I ₁/I ₃, as the pyrene (Py) scale] of fluorescent Py was used to monitor the critical concentration, drug-loading, and -releasing behaviors of a Py-terminated, amphiphilic polypeptide PPM and its hydrogen-bonded interpolymer complex (HIPC) with poly(acrylic acid) (PAA). Primarily, an amphiphilic PPM with a hydrophobic Py terminal and hydrophilic methoxy-bis(ethylene oxide) pendant groups was synthesized through multiple preparative steps, and the resultant PPM was thoroughly mixed with PAA through a preferable hydrogen bond (H bond) interaction to form HIPC. The emission study suggested that the I ₁/I ₃ ratio and the quantum yield (Φ_F) are effective in determining the critical concentrations of the aqueous PPM and PPM/PAA solutions. Moreover, the I ₁/I ₃ ratio and Φ_F were found to be convenient measures for determining the amounts of doxorubicin drugs loaded by and released from the aqueous PPM and PPM/PAA solutions.

Diphenylpyrenylamine-functionalized polypeptides: secondary structures, aggregation-induced emission, and carbon nanotube dispersibility

In this study we prepared-through ring-opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA) initiated by N,N-di(4-aminophenyl)-1-aminopyrene (pyrene-DPA-2NH2)-poly(γ-benzyl-l-glutamate) (PBLG) polymers with various degrees of polymerization (DP), each featuring a di(4-aminophenyl)pyrenylamine (DPA) luminophore on the main backbone. The secondary structures of these pyrene-DPA-PBLG polypeptides were investigated using Fourier transform infrared spectroscopy and wide-angle X-ray diffraction, revealing that the polypeptides with DPs of less than 19 were mixtures of α-helical and β-sheet conformations, whereas the α-helical structures were preferred for longer chains. Interestingly, pyrene-DPA-2NH2 exhibited weak photoluminescence (PL), yet the emission of the pyrene-DPA-PBLG polypeptides was 16-fold stronger, suggesting that attaching PBLG chains to pyrene-DPA-2NH2 turned on a radiative pathway for the non-fluorescent molecule. Furthermore, pyrene-DPA-2NH2 exhibited aggregation-caused quenching; in contrast, after incorporation into the PBLG segments with rigid-rod conformations, the resulting pyrene-DPA-PBLG polypeptides displayed aggregation-induced emission. Transmission electron microscopy revealed that mixing these polypeptides with multiwalled carbon nanotubes (MWCNTs) in DMF led to the formation of extremely dispersible pyrene-DPA-PBLG/MWCNT composites. The fabrication of MWCNT composites with such biocompatible polymers should lead to bio-inspired carbon nanostructures with useful biomedical applications.

Multivalent effect of glycopolypeptide based nanoparticles for galectin binding

Synthetic glycopolypeptides are versatile glycopolymers used to conceive bioinspired nanoassemblies. In this work, novel amphiphilic glycopolypeptides were designed to incorporate lactose or galactan in order to prepare polymeric nanoassemblies with sizes below 50 nm. The bioactivity of the two different outer surface sugar units was evaluated by defining glycan relative binding affinities to human galectins 1 and 3. A specific multivalent effect was found only for polymeric nanoparticles displaying galactan with a significant increase of the binding activity as compared to free glycan in solution. Such synthetic designs present great potential as therapeutic tools to address galectin related pathologies.

A glutathione-responsive sulfur dioxide polymer prodrug as a nanocarrier for combating drug-resistance in cancer chemotherapy

Multidrug resistance (MDR) in cancer remains a significant challenge for curing cancer by chemotherapy. In this work, a kind of glutathione (GSH)-responsive polymer prodrug of SO₂ was designed and synthesized, which presented synergistic effect with doxorubicin (DOX) for combating MCF-7 ADR human breast cancer cell. Firstly, a small molecular prodrug of SO₂, N-(3-azidopropyl)-2,4-dinitrobenzenesulfonamide (AP-DNs), was chemically conjugated onto the side chain of methoxy poly (ethylene glycol)-block-poly (γ-propargyl-l-glutamate) (mPEG-PPLG) block copolymer to generate an amphiphilic polymer prodrug of SO₂, mPEG-PLG (DNs). The obtained mPEG-PLG (DNs) prodrug could self-assemble into micelles in aqueous media and release SO₂ rapidly in response to thiol compounds. Then, DOX was loaded into mPEG-PLG (DNs) nanoparticles with ultrahigh drug-loading efficiency (97.3%). In vitro drug release tests indicated that the DOX-loaded nanoparticles could simultaneously release SO₂ and DOX by GSH triggering. Moreover, the effective cellular uptake of the DOX-loaded nanoparticles and subsequent intracellular release of SO₂ and DOX were verified by confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) analyses. The released SO₂ could promote the reactive oxygen species (ROS) level in tumor cells, which thereby resulted in oxidative damages of cancer cells, together with restoration of MCF-7 ADR cells sensitivity to DOX. As a result, the released DOX and SO₂ showed synergistic therapeutic effect against MCF-7 ADR cells. In vivo antitumor evaluation further indicated that, compared with free DOX, the DOX-loaded nanoparticles exhibited better antitumor effect in a MCF-7 ADR-xenografted nude mice model while had lower system toxicity. Overall, we demonstrated, for the first time, that a SO₂ polymer prodrug, acting as a stimuli-responsive nanocarrier to codeliver DOX, can efficiently inhibit the proliferation of MDR tumor cells, which may offer a new weapon for combating MDR in cancer therapy.

Tuning carbohydrate density enhances protein binding and inhibition by glycosylated β-sheet peptide nanofibers

The efficacy of glycosylated β-sheet peptide nanofibers for inhibiting carbohydrate-binding proteins can be increased by tuning carbohydrate density to maximize protein binding affinity.

Amino acid-derived stimuli-responsive polymers and their applications

The recent advances achieved in the study of various stimuli-responsive polymers derived from natural amino acids have been reviewed.

Strategies to Fabricate Polypeptide-Based Structures via Ring-Opening Polymerization of N-Carboxyanhydrides

In this review, we provide a general and clear overview about the different alternatives reported to fabricate a myriad of polypeptide architectures based on the ring-opening polymerization of N-carbonyanhydrides (ROP NCAs). First of all, the strategies for the preparation of NCA monomers directly from natural occurring or from modified amino acids are analyzed. The synthetic alternatives to prepare non-functionalized and functionalized NCAs are presented. Protection/deprotection protocols, as well as other functionalization chemistries are discussed in this section. Later on, the mechanisms involved in the ROP NCA polymerization, as well as the strategies developed to reduce the eventually occurring side reactions are presented. Finally, a general overview of the synthetic strategies described in the literature to fabricate different polypeptide architectures is provided. This part of the review is organized depending on the complexity of the macromolecular topology prepared. Therefore, linear homopolypeptides, random and block copolypeptides are described first. The next sections include cyclic and branched polymers such as star polypeptides, polymer brushes and highly branched structures including arborescent or dendrigraft structures.

Glycoproteins functionalized natural and synthetic polymers for prospective biomedical applications: A review

Glycoproteins have multidimensional properties such as biodegradability, biocompatibility, non-toxicity, antimicrobial and adsorption properties; therefore, they have wide range of applications. They are blended with different polymers such as chitosan, carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), polycaprolactone (PCL), heparin, polystyrene fluorescent nanoparticles (PS-NPs) and carboxyl pullulan (PC) to improve their properties like thermal stability, mechanical properties, resistance to pH, chemical stability and toughness. Considering the versatile charateristics of glycoprotein based polymers, this review sheds light on synthesis and characterization of blends and composites of glycoproteins, with natural and synthetic polymers and their potential applications in biomedical field such as drug delivery system, insulin delivery, antimicrobial wound dressing uses, targeting of cancer cells, development of anticancer vaccines, development of new biopolymers, glycoproteome research, food product and detection of dengue glycoproteins. All the technical scientific issues have been addressed; highlighting the recent advancement.

Bioreducible amphiphilic block copolymers based on PCL and glycopolypeptide as multifunctional theranostic nanocarriers for drug delivery and MR imaging

Amphiphilic diblock poly(ε-caprolactone)-b-glycopolypeptides (PCL–SS–GPPs) bearing disulfide bonds were synthesized from a clickable poly(ε-caprolactone)–SS–poly(2-azidoethyl-l-glutamate) diblock copolymer.

Orthogonally reactive amino acids and end groups in NCA polymerization

We summarize recent strategies for the synthesis of orthogonally reactive polypeptides and polypeptoids by direct and post-polymerization approaches.

Controlled Synthesis of End-Functionalized Mannose-6-phosphate Glycopolypeptides for Lysosome Targeting

The ubiquitous expression of the mannose-6-phosphate receptor on the majority of human cells makes it a valid target in the quest to deliver therapeutics selectively to the lysosome. In this work end-functionalized polyvalent mannose-6-phosphate glycopolypeptides (M6P-GPs) with high molecular weights (up to 22 kDa) have been synthesized via NCA polymerization. These synthetic M6P-GPs were found to display minimal toxicity to cells in vitro and show exceptional selectivity for trafficking into lysosomes in various cell lines. Comparison of the cellular uptake behavior of M6P-GP and the corresponding mannose-GP polymer reveals that incorporation of the phosphate moiety at the 6-position of mannose completely alters its trafficking behavior and becomes exclusively lysosome specific. We also demonstrate that trafficking of M6P-GPs in mammalian cells is likely associated with the CI-MPR receptor pathway.

One-Step "Click Chemistry"-Synthesized Cross-Linked Prodrug Nanogel for Highly Selective Intracellular Drug Delivery and Upregulated Antitumor Efficacy

Polymeric prodrugs formed by the conjugation of drugs onto polymers have shown great promise in cancer therapy because of the enhancement of water solubility, elimination of premature drug release, and the improvement of pharmacokinetics. To integrate the two advantages of upregulated stability during circulation and selective release of drug in cancer cells, a pH and reduction dual-sensitive prodrug nanogel (CLP) was synthesized via a simple one step "click chemistry". CLP was spherically shaped with a uniform diameter of 60.6 ± 13.7 nm and exhibited great stability in size against large volume dilution, high salt concentration, and long-time incubation in phosphate-buffered saline. Owing to the presence of hydrazone-bonded doxorubicin (DOX) and disulfide cross-linker, CLP released minimal amount (7.8%) of drug under normal physiological pH (i.e., 7.4) condition. But it released 85.5% of the loaded DOX at endosomal pH (i.e., 5.5) plus the presence of 5.0 mM GSH in 120 h. CLP could be effectively internalized by tumor cells and subsequently release DOX in the intracellular environment, resulting in effective proliferation inhibition of HeLa and MCF-7 cells. Furthermore, compared with free DOX and non-cross-linked prodrug micelle (NCLP), CLP accumulated more in tumor site but less in the normal organs, so that CLP performed the enhanced antitumor efficiency and reduced side-toxicities toward the MCF-7 human breast cancer xenograft nude mouse model. With convenient fabrication, favorable stability, controlled release properties, optimized biodistribution, and enhanced suppression of tumor growth, CLP held great potential for optimal antitumor therapy.

Well-defined (co)polypeptides bearing pendant alkyne groups

A novel metal-free strategy, using hydrogen-bonding catalytic ring opening polymerization of alkyne-functionalized N-carboxy anhydrites of α-amino acids, was developed for the synthesis of well-defined polypeptides bearing pendant alkyne groups.

Biodegradable thermal- and redox-responsive poly(l-glutamate) with Y-shaped oligo(ethylene glycol) side-chain and tunable phase transition temperature

A series of poly(l-glutamate) bearing Y-shaped oligo(ethylene glycol)_x side-chains were synthesized via a combination of ROP and thiol–yne photoaddition. The polypeptides showed dual thermal and redox-responsive properties.

Controlled Synthesis and Enzyme-Induced Hydrogelation of Poly(l-phosphotyrosine)s via Ring-Opening Polymerization of α-Amino Acid N-Carboxyanhydride

Tyrosine phosphorylation is an important post-translational modification (PTM) that governs numerous cellular processes. Constructing synthetic phosphotyrosine polypeptides helps expand the horizon of our understanding regarding the fundamental aspects and biological consequences of this PTM. Here, we report the synthesis of a novel monomer, O-diethylphospho l-tyrosine N-carboxyanhydride (pOEt TyrNCA), whose ring-opening polymerization (ROP) mediated by hexamethyldisilazane (HMDS) leads to poly(l-phosphotyrosine) (P(pTyr)) derivatives with controllable molecular weights and narrow molecular-weight distributions. Moreover, P(pTyr)₁₅-b-PEG-b-P(pTyr)₁₅ triblock copolymer (TBP15) undergo sol-gel transition in the presence of alkaline phosphatase. The stiffness of the gel is reinforced by the addition of horseradish peroxidase and hydrogen peroxide. These phosphotyrosine-mimicking polymers are realized for the first time by NCA polymerization and are promising materials for a variety of biological applications.

ε-Methacryloyl-l-lysine based polypeptides and their thiol–ene click functionalization

l-Lysine-based polypeptides containing methacryloyl pendants were synthesized, which can be facilely functionalized with various functional molecules through a “thiol–ene” reaction.