Chirality-mediated polypeptide micelles for regulated drug delivery

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Polypeptide-Based Systems: From Synthesis to Application in Drug Delivery

Synthetic polypeptides are biocompatible and biodegradable macromolecules whose composition and architecture can vary over a wide range. Their unique ability to form secondary structures, as well as different pathways of modification and biofunctionalization due to the diversity of amino acids, provide variation in the physicochemical and biological properties of polypeptide-containing materials. In this review article, we summarize the advances in the synthesis of polypeptides and their copolymers and the application of these systems for drug delivery in the form of (nano)particles or hydrogels. The issues, such as the diversity of polypeptide-containing (nano)particle types, the methods for their preparation and drug loading, as well as the influence of physicochemical characteristics on stability, degradability, cellular uptake, cytotoxicity, hemolysis, and immunogenicity of polypeptide-containing nanoparticles and their drug formulations, are comprehensively discussed. Finally, recent advances in the development of certain drug nanoformulations for peptides, proteins, gene delivery, cancer therapy, and antimicrobial and anti-inflammatory systems are summarized.

Rational design and engineering of polypeptide/protein vesicles for advanced biological applications

Synthetic vesicles have gained considerable popularity in recent years for numerous biological and medical applications. Among the various types of synthetic vesicles, the utilization of polypeptides and/or proteins as fundamental constituents has garnered significant interest for vesicle construction owing to the unique bio-functionalities inherent in rationally designed amino acid sequences. Especially the incorporation of functional proteins onto the vesicle surface facilitates a wide range of advanced biological applications that are not easily attainable with traditional building blocks, such as lipids and polymers. The main goal of this review is to provide a comprehensive overview of the latest advancements in polypeptide/protein vesicles. Moreover, this review encompasses the rational design and engineering strategies employed in the creation of polypeptide/protein vesicles, including the synthesis of building blocks, the modulation of their self-assembly, as well as their diverse applications. Furthermore, this work includes an in-depth discussion of the key challenges and opportunities associated with polypeptide/protein vesicles, providing valuable insights for future research. By offering an up-to-date review of this burgeoning field of polypeptide/protein vesicle research, this review will shed light on the potential applications of these biomaterials.

The Role of Nanotechnology in Spinal Cord Tumors

The efficacy of current multimodal therapeutic strategies in spinal cord tumors is limited by the lack of specific therapies. Importantly, sufficient amount of therapeutic materials should be concentrated in tumors in order to be efficient. Overcoming the blood-brain barrier is the major obstacle for chemotherapeutics, which cannot reach the tumor bed in efficacious doses. The intrinsic properties of nanoparticles make them suitable for activating numerous processes both at the cellular and subcellular levels, making them good candidates to be used for different purposes in medicine. Furthermore, the adaptability characteristic of NPs may enable them to pass through the blood-brain barrier and transport different pharmacological compounds. Nanoparticle systems provide prolonged drug delivery directly to the tumor or by functionalizing the material surface with peptides and ligands allowing the drug-loaded material to specifically target the tumor cells. In this chapter, various preclinical and/or clinical studies in treatment of spinal cord tumors are discussed.

Molecular Targeted Agent and Immune Checkpoint Inhibitor Co-Loaded Thermosensitive Hydrogel for Synergistic Therapy of Rectal Cancer

Molecular targeted therapy has been proved effective in treatment of rectal cancer. Up-regulated expression of programmed death ligand-1 (PD-L1) was observed after the management of molecular targeted therapy, which made the therapeutic effect discounted. Tumors with higher PD-L1 expression were more sensitive and responsive to treatment of PD-L1 inhibitor. Therefore, the combination of molecular targeted therapy and immune checkpoint blockade makes sense. In this study, the copolymers of poly (ethylene glycol)-block-poly (_L-leucine) (PEG-PLLeu) were synthesized as a thermosensitive hydrogel composite for consecutive release of regorafenib (REG) and BMS202. The mechanical properties of PEG-PLLeu were investigated, confirming that PEG-PLLeu (5 wt.%) was suitable for in situ injection as drug-delivery composite at low temperature and stable after sol-gel transition at body temperature. Importantly, the double drug loaded hydrogel showed superior antitumour activity over single drugs in an orthotopic rectal cancer model (CT26-Luc). Further analysis of the tumor tissues suggested that REG upregulated the expression of PD-L1 in tumor tissues. In addition, the immunosuppressive tumor microenvironment of CT26-Luc tumor was distinctly relieved under the effect of BMS202, as characterized by increased infiltration of CD8⁺ T cells in tumors and enhanced secretion of antitumour cytokines (IFN-γ and TNF-α). Moreover, the drug-loaded composite showed no obvious toxicity in histological analysis. Taken together, the administration of REG and BMS202 in the PEG-PLLeu composite could induce a synergistic effect in in situ treatment of rectal cancer without obvious toxicity, and thus represented a potential strategy for enhanced in situ therapeutic modality.

Calcium-mineralized polypeptide nanoparticle for intracellular drug delivery in osteosarcoma chemotherapy

The acidic microenvironments of tumor tissue and cells provide an opportunity for the development of pH-responsive drug delivery systems in cancer therapy. In this work, we designed a calcium carbonate (CaCO₃)-core-crosslinked nanoparticle of methoxy poly(ethylene glycol)-block-poly(l-glutamic acid) through mineralization for intracellular delivery of doxorubicin (DOX), referred to as ^CaNP/DOX. ^CaNP/DOX exhibited high drug loading capability, uniform nanoparticle size, and pH-dependent DOX release. In the meantime, the enhanced cell uptake, superior cytotoxicity toward mouse osteosarcoma K7 cells, extended circulation half-life, and improved accumulation of DOX in K7 allograft tumor from ^CaNP/DOX were also demonstrated. More interestingly, ^CaNP/DOX displayed improved antitumor effect and reduced side effects against the K7 osteosarcoma-allografted mouse model and the 143B orthotopic osteosarcoma mouse model. Given the superior properties of Ca-mineralized polypeptide nanoparticle for intracellular drug delivery, the smart drug delivery system showed strong competitiveness in clinical chemotherapy of cancers.

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A doxorubicin-loaded calcium carbonate-crosslinked polypeptide nanoparticle (^CaNP/DOX) is prepared by mineralization.

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^CaNP/DOX with high drug-loading efficiency and uniform nanoparticle size is developed for intracellular drug delivery in osteosarcoma chemotherapy.

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^CaNP/DOX exhibits prolonged circulation half-life and upregulated intratumoral accumulation.

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^CaNP/DOX shows enhanced antitumor efficacy and reduced side effects toward subcutaneous and orthotopic osteosarcoma models in mice.

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^CaNP/DOX demonstrates great potential in the clinical chemotherapy of various cancers.

Prediction of Amphiphilic Cell-Penetrating Peptide Building Blocks from Protein-Derived Amino Acid Sequences for Engineering of Drug Delivery Nanoassemblies

Amphiphilic molecules, forming self-assembled nanoarchitectures, are typically composed of hydrophobic and hydrophilic domains. Peptide amphiphiles can be designed from two, three, or four building blocks imparting novel structural and functional properties and affinities for interaction with cellular membranes or intracellular organelles. Here we present a combined numerical approach to design amphiphilic peptide scaffolds that are derived from the human nuclear K_i-67 protein. K_i-67 acts, like a biosurfactant, as a steric and electrostatic charge barrier against the collapse of mitotic chromosomes. The proposed predictive design of new K_i-67 protein-derived amphiphilic amino acid sequences exploits the computational outcomes of a set of web-accessible predictors, which are based on machine learning methods. The ensemble of such artificial intelligence algorithms, involving support vector machine (SVM), random forest (RF) classifiers, and neural networks (NN), enables the nanoengineering of a broad range of innovative peptide materials for therapeutic delivery in various applications. Amphiphilic cell-penetrating peptides (CPP), derived from natural protein sequences, may spontaneously form self-assembled nanocarriers characterized by enhanced cellular uptake. Thanks to their inherent low immunogenicity, they may enable the safe delivery of therapeutic molecules across the biological barriers.

Ring opening polymerization of α-amino acids: advances in synthesis, architecture and applications of polypeptides and their hybrids

This review provides a comprehensive overview of the latest advances in the synthesis, architectural design and biomedical applications of polypeptides and their hybrids.

Polypeptide Nanogels With Different Functional Cores Promote Chemotherapy of Lung Carcinoma

Two kinds of tumor microenvironment-responsive polypeptide nanogels were developed for intracellular delivery of cytotoxics to enhance the antitumor efficacies and reduce the side effects in the chemotherapy of lung carcinoma. The sizes of both doxorubicin (DOX)-loaded nanogels methoxy poly(ethylene glycol)-poly(L-phenylalanine-co-L-cystine) [mPEG-P(LP-co-LC)] and methoxy poly(ethylene glycol)-poly(L-glutamic acid-co-L-cystine) [mPEG-P(LG-co-LC)] (NGP/DOX and NGG/DOX) were less than 100 nm, which was appropriate for the enhanced permeability and retention (EPR) effect. The bigger and smaller scale of nanoparticle could induce the elimination of reticuloendothelial system (RES) and decrease the in vivo circulating half-life, respectively. The loading nanogels were stable in the neutral environment while quickly degraded in the mimic intracellular microenvironment. Furthermore, the DOX-loaded reduction-responsive nanogels showed significantly higher tumor cell uptake than free DOX⋅HCl as time went on from 2 to 6 h. In addition, these DOX-loaded nanogels showed efficient antitumor effects in vivo, which was verified by the obviously increased necrosis areas in the tumor tissues. Furthermore, these DOX-loaded nanogels efficiently reduced the side effects of DOX. In conclusion, these reduction-responsive polypeptides based nanogels are suitable for the efficient therapy of lung carcinoma.

Self-Stabilized Hyaluronate Nanogel for Intracellular Codelivery of Doxorubicin and Cisplatin to Osteosarcoma

Osteosarcoma is one of the most serious bone malignancies with rapid speed of deterioration and low survival rate in children and teenagers. Chemotherapy is an important treatment for osteosarcoma, while the conventional small-molecule therapeutics exhibit low efficacies and severe side effects in the clinic. Drug-delivery platforms based on nanotechnology, particularly for self-stabilized delivery platforms with prolonged blood circulation, enhanced intratumoral accumulation, improved antitumor efficacy, and diminished side effects, may break the deadlock on osteosarcoma chemotherapy. Here, a cisplatin (CDDP)-crosslinked hyaluronic acid (HA) nanogel (CDDPHANG) is prepared for effective delivery of doxorubicin (DOX) to treat osteosarcoma. Importantly, both DOX and CDDP have led clinically used antitumor drugs, and CDDP acts as a crosslinker and ancillary anticarcinogen to prevent the premature release of DOX and to achieve synergistic therapeutic performance. Because of the enhanced stability of the nanogel, this CDDP-crosslinked DOX-loaded nanomedicine (CDDPHANG/DOX) exhibits an obviously prolonged circulation time compared to free drugs. Moreover, after valid tumor accumulation, DOX and CDDP are synergistically delivered into the tumor cells and synchronously released into the intracellular acidic environment. Based on the synergistic apoptosis-inducing effects of DOX and CDDP, CDDPHANG/DOX reveals an evidently enhanced antitumor efficacy compared to free drugs and their combination, indicating its great prospects for the chemotherapy of osteosarcoma.

Polypeptide self-assemblies: nanostructures and bioapplications

Polypeptide copolymers can self-assemble into diverse aggregates. The morphology and structure of aggregates can be varied by changing molecular architectures, self-assembling conditions, and introducing secondary components such as polymers and nanoparticles. Polypeptide self-assemblies have gained significant attention because of their potential applications as delivery vehicles for therapeutic payloads and as additives in the biomimetic mineralization of inorganics. This review article provides an overview of recent advances in nanostructures and bioapplications related to polypeptide self-assemblies. We highlight recent contributions to developing strategies for the construction of polypeptide assemblies with increasing complexity and novel functionality that are suitable for bioapplications. The relationship between the structure and properties of the polypeptide aggregates is emphasized. Finally, we briefly outline our perspectives and discuss the challenges in the field.

Environment-stimulated nanocarriers enabling multi-active sites for high drug encapsulation as an “on demand” drug release system

Limited active sites in polyesters hinder fabrication of multifunctional biodegradable nanocarriers for successful clinical applications.

Polymer micro/nanocarrier-assisted synergistic chemohormonal therapy for prostate cancer

Polymer micro/nanocarrier-assisted chemohormonal therapy upregulates chemotherapy efficacy and down-regulates hormone level, effectively inhibiting the progression of prostate cancer.

Biodegradable Micelles Based on Poly(ethylene glycol)-b-polylipopeptide Copolymer: A Robust and Versatile Nanoplatform for Anticancer Drug Delivery

Poly(ethylene glycol)-b-polypeptide block copolymer micelles, with excellent safety, are one of the most clinically studied nanocarriers for anticancer drug delivery. Notably, self-assembled nanosystems based on hydrophobic polypeptides showing typically a low drug loading and burst drug release are limited to preclinical studies. Here, we report that poly(ethylene glycol)-b-poly(α-aminopalmitic acid) (PEG-b-PAPA) block copolymer could be easily prepared with tailored M_n through ring-opening polymerization of α-aminopalmitic acid N-carboxyanhydride (APA-NCA). Interestingly, PEG-b-PAPA copolymers exhibited superb solubility in common organic solvents (including CHCl₃, CH₂Cl₂, and THF), while stable nanomicelles were formed in phosphate buffer, with a small size of 59 nm and a low critical micelle concentration of 2.38 mg/L. These polylipopeptide micelles (Lipep-Ms) allowed facile loading of a potent anticancer drug, docetaxel (DTX), likely due to the existence of a strong interaction between the lipophilic drug and polylipopeptide in the core. Notably, cRGD-peptide-functionalized Lipep-Ms (cRGD-Lipep-Ms) were also obtained with similar biophysical characteristics. The in vitro studies showed efficient cellular uptake of DTX-loaded cRGD-Lipep-Ms by B16F10 cells and fast intracellular drug release due to the enzymatic degradation of PAPA blocks in endo/lysosome, leading to a pronounced anticancer effect (IC₅₀ = 0.15 μg DTX equiv/mL). The in vivo therapy studies showed that DTX-cRGD-Lipep-Ms exhibited superior tumor growth inhibition of B16F10 melanoma, improved survival rate, and little side effects as compared to free DTX. These polylipopeptide micelles appear as a promising and robust nanoplatform for anticancer drug delivery.

Micelles Formed by Polypeptide Containing Polymers Synthesized Via N-Carboxy Anhydrides and Their Application for Cancer Treatment

The development of multifunctional polymeric materials for biological applications is mainly guided by the goal of achieving the encapsulation of pharmaceutical compounds through a self-assembly process to form nanoconstructs that control the biodistribution of the active compounds, and therefore minimize systemic side effects. Micelles are formed from amphiphilic polymers in a selective solvent. In biological applications, micelles are formed in water, and their cores are loaded with hydrophobic pharmaceutics, where they are solubilized and are usually delivered through the blood compartment. Even though a large number of polymeric materials that form nanocarrier delivery systems has been investigated, a surprisingly small subset of these technologies has demonstrated potentially curative preclinical results, and fewer have progressed towards commercialization. One of the most promising classes of polymeric materials for drug delivery applications is polypeptides, which combine the properties of the conventional polymers with the 3D structure of natural proteins, i.e., α-helices and β-sheets. In this article, the synthetic pathways followed to develop well-defined polymeric micelles based on polypeptides prepared through ring-opening polymerization (ROP) of N-carboxy anhydrides are reviewed. Among these works, we focus on studies performed on micellar delivery systems to treat cancer. The review is limited to systems presented from 2000⁻2017.

Boronic Acid as Glucose-Sensitive Agent Regulates Drug Delivery for Diabetes Treatment

In recent years, glucose-sensitive drug delivery systems have attracted considerable attention in the treatment of diabetes. These systems can regulate payload release by the changes of blood glucose levels continuously and automatically with potential application in self-regulated drug delivery. Boronic acid (BA), especially phenylboronic acid (PBA), as glucose-sensitive agent has been the focus of research in the design of glucose-sensitive platforms. This article reviews the previous attempts at the developments of PBA-based glucose-sensitive drug delivery systems regarding the PBA-functionalized materials and glucose-triggered drug delivery. The obstacles and potential developments of glucose-sensitive drug delivery systems based on PBA for diabetes treatment in the future are also described. The PBA-functionalized platforms that regulate drug delivery induced by glucose are expected to contribute significantly to the design and development of advanced intelligent self-regulated drug delivery systems for treatment of diabetes.

Strategies for improving the payload of small molecular drugs in polymeric micelles

In the past few years, substantial efforts have been made in the design and preparation of polymeric micelles as novel drug delivery vehicles. Typically, polymeric micelles possess a spherical core-shell structure, with a hydrophobic core and a hydrophilic shell. Consequently, poorly water-soluble drugs can be effectively solubilized within the hydrophobic core, which can significantly boost their drug loading in aqueous media. This leads to new opportunities for some bioactive compounds that have previously been abandoned due to their low aqueous solubility. Even so, the payload of small molecular drugs is still not often satisfactory due to low drug loading and premature release, which makes it difficult to meet the requirements of in vivo studies. This problem has been a major focus in recent years. Following an analysis of the published literature in this field, several strategies towards achieving polymeric micelles with high drug loading and stability are presented in this review, in order to ensure adequate drug levels reach target sites.

Injectable Hydrogel-Microsphere Construct with Sequential Degradation for Locally Synergistic Chemotherapy

In recent years, in situ chemotherapy mediated by biodegradable polymer platforms has attracted increased attention. Herein, an advanced drug delivery system, combretastatin A-4 (CA4) and docetaxel (DTX)-loaded microsphere embedded in injectable thermosensitive polypeptide hydrogel (i.e., hydrogel-microsphere (Gel-MP) construct), was reported for sequential release of drugs with different mechanisms to treat osteosarcoma synergistically. The Gel-MP construct showed sequential biodegradability and excellent biocompatibility. CA4 was preferentially released from hydrogel with faster degradation to disturb the vascular structure of the tumor and reduce the exchange of nutrients between the tumor and surrounding tissues, which created interstitial space in the tissue for DTX penetration to inhibit tumor cell proliferation. The in vivo treatment with Gel/CA4-MP/DTX efficiently suppressed the growth of mouse K7 osteosarcoma compared to other formulations. More importantly, by systematical study of histopathology and immunohistochemistry, the Gel-MP construct can significantly upregulate antiproliferation effect and reduce toxicity of drugs. Therefore, this injectable and locally sequential delivery system has a bright prospect in clinical application of in situ synergistic chemotherapy.

Polypeptide-participating complex nanoparticles with improved salt-tolerance as excellent candidates for intelligent insulin delivery

The strategy of introducing synthetic polypeptides with hierarchical ordered structures into glucose-responsive materials is reported in this study to achieve self-regulated release of insulin under physiological salt concentration.

Synthetic polypeptides: from polymer design to supramolecular assembly and biomedical application

This review highlights the recent advances in the chemical design, supramolecular assembly, and biomedical application of synthetic polypeptides fromN-carboxyanhydrides.

Thermosensitive Polypeptide Hydrogels as a Platform for ROS-Triggered Cargo Release with Innate Cytoprotective Ability under Oxidative Stress

Reactive oxygen species (ROS) play important roles in cell signaling pathways, while increased production of ROS may disrupt cellular homeostasis, giving rise to a series of diseases. Therefore, materials responding to ROS at physiological levels are of great significance. In this work, a novel ROS-responsive thermogelling hydrogel based on methoxy poly(ethylene glycol)-poly(l-methionine) diblock copolymers is designed and synthesized. The mechanism for solution-to-hydrogel (sol-gel) phase transitions of the copolymer aqueous solutions is studied. Incubation of the hydrogels in the presence of peroxide hydrogen (H2 O2 ) displays a H2 O2 -responsive degradation process. The hydrogels containing Rhodamine 6G exhibit sustained release profiles that are accelerated in response to H2 O2 . An innate cytoprotective ability of the hydrogels is revealed by incubation of L929 cells with the hydrogels under oxidative stress, which reduces H2 O2 -mediated cell death. ROS produced by activated macrophages can accelerate the erosion of the hydrogel, suggesting that the hydrogel is also responsive to pathological level of H2 O2 . Meanwhile, the poly(l-methionine)-based hydrogels degrade within 6 weeks after subcutaneous injection into rats, with a good biocompatibility in vivo. Overall, the injectable, ROS-responsive hydrogels may serve as promising platforms for sustained drug delivery and cell-based therapies in treatment of diseases with local oxidative stress.

One-pot synthesis of dextran decorated reduced graphene oxide nanoparticles for targeted photo-chemotherapy

Graphene-based nanocarriers show great potential in photo-chemotherapy, however, to prepare desired reduced graphene oxide (rGO) nanoparticles in a facile way is still a challenge. Herein, a novel strategy has been presented to prepare rGO nanoparticle using dextran (Dex) as a reducing agent. In this strategy, Dex was directly conjugated on rGO by hydrogen bond and then self-assemble to form rGO/Dex nanoparticles. After decorated by dextran, rGO-based nanoparticles not only show excellent biocompatibility but also can load anticancer drug for photo-chemotherapy. The data of fourier transform infrared (FT-IR) analysis, Raman spectrum analysis, thermos-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), the transmission electron microscope (TEM) image and dynamic light scattering (DLS) measurements powerfully proved that the stable rGO-based nanoparticles with desired nanosize have been successfully prepared. To verify the photo-chemotherapy, anticancer drug, doxorubicin (DOX), has been loaded on rGO/Dex nanoparticles (rGO/DOX/Dex). And RGD, a kind of oligopeptide which can improve the intracellular uptake by αvβ3 recognition, also has been introduced (rGO/DOX/RDex). Compared with single chemotherapy, rGO/DOX/Dex and rGO/DOX/RDex combining the local specific chemotherapy and external near-infrared (NIR) photo-thermal therapy show higher therapeutic efficacy, endowing the desired rGO-based nanoparticle with great potential for cancer treatments.

Zwitterionic-Modified Starch-Based Stealth Micelles for Prolonging Circulation Time and Reducing Macrophage Response

Over the last few decades, nanoparticles have been emerging as useful means to improve the therapeutic efficacy of drug delivery and medical diagnoses. However, the heterogeneity and complexity of blood as a medium is a fundamental problem; large amounts of protein can be adsorbed onto the surface of nanoparticles and cause their rapid clearance before reaching their target sites, resulting in the failure of drug delivery. To overcome this challenge, we present a rationally designed starch derivative (SB-ST-OC) with both a superhydrophilic moiety of zwitterionic sulfobetaine (SB) and a hydrophobic segment of octane (OC) as functional groups, which can self-assemble into "stealth" micelles (SSO micelles). The superhydrophilic SB kept the micelles stable against aggregation in complex media and imbued them with "stealth" properties, eventually extending their circulation time in blood. In stability and hemolysis tests the SSO micelles showed excellent protein resistance properties and hemocompatibility. Moreover, a phagocytosis test and cytokine secretion assay confirmed that the SSO micelles had less potential to trigger the activation of macrophages and were more suitable as a drug delivery candidate in vivo. On the basis of these results, doxorubicin (DOX), a hydrophobic drug, was used to investigate the potential application of this novel starch derivative in vivo. The results of the pharmacokinetic study showed that the values of the plasma area under the concentration curve (AUC) and elimination half-life (T1/2) of the SSO micelles were higher than those of micelles without SB modifications. In conclusion, the combination of excellent protein resistance, lower macrophage activation, and longer circulation time in vivo makes this synthesized novel starch derivative a promising candidate as a hydrophobic drug carrier for long-term circulation in vivo.

Decorated reduced graphene oxide for photo-chemotherapy

The biocompatibility and toxicity are still the key issues for graphene-based nanocarriers in the application of photothermal therapy. Herein, a novel surface modification strategy to prepare dextran decorated reduced graphene oxide (rGO) sheets has been presented. In this strategy, octadecanic acid is conjugated on dextran and used as a hydrophobic anchor to prepare dextran decorated rGO sheets. After being decorated by dextran, rGO sheets not only show excellent biocompatibility but also can load anticancer drugs for photo-chemotherapy. The data of Fourier transform infrared (FT-IR) analysis, Raman spectrum analysis, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), the transmission electron microscopy (TEM) image and dynamic light scattering (DLS) measurements powerfully prove that the desired rGO compound with the ideal nano-size has been successfully prepared and is stable enough. To verify the photo-chemotherapy, an anticancer drug, doxorubicin (DOX), has been loaded into the decorated rGO sheets (rGO/DOX/C18D). Furthermore, to improve the intracellular uptake, folic acid (FA), as a common target molecule, has been introduced (rGO/DOX/C18DF). Compared with single chemotherapy, rGO/DOX/C18D and rGO/DOX/C18DF combining the local specific chemotherapy and external near-infrared (NIR) photo-thermal therapy show higher therapeutic efficacy, endowing the decorated rGO nanoparticle with great potential for cancer treatments.

Mesomeric configuration makes polyleucine micelle an optimal nanocarrier

Mesomeric polyleucine micelle with cRGD decoration is selected as a promising targeting drug delivery system.

Stereocomplex micelle from nonlinear enantiomeric copolymers efficiently transports antineoplastic drug

Nanoscale polymeric micelles have attracted more and more attention as a promising nanocarrier for controlled delivery of antineoplastic drugs. Herein, the doxorubicin (DOX)-loaded poly(D-lactide)-based micelle (PDM/DOX), poly(L-lactide)-based micelle (PLM/DOX), and stereocomplex micelle (SCM/DOX) from the equimolar mixture of the enantiomeric four-armed poly(ethylene glycol)-polylactide (PEG-PLA) copolymers were successfully fabricated. In phosphate-buffered saline (PBS) at pH 7.4, SCM/DOX exhibited the smallest hydrodynamic diameter (D h) of 90 ± 4.2 nm and the slowest DOX release compared with PDM/DOX and PLM/DOX. Moreover, PDM/DOX, PLM/DOX, and SCM/DOX exhibited almost stable D hs of around 115, 105, and 90 nm at above normal physiological condition, respectively, which endowed them with great potential in controlled drug delivery. The intracellular DOX fluorescence intensity after the incubation with the laden micelles was different degrees weaker than that incubated with free DOX · HCl within 12 h, probably due to the slow DOX release from micelles. As the incubation time reached to 24 h, all the cells incubated with the laden micelles, especially SCM/DOX, demonstrated a stronger intracellular DOX fluorescence intensity than free DOX · HCl-cultured ones. More importantly, all the DOX-loaded micelles, especially SCM/DOX, exhibited potent antineoplastic efficacy in vitro, excellent serum albumin-tolerance stability, and satisfactory hemocompatibility. These encouraging data indicated that the loading micelles from nonlinear enantiomeric copolymers, especially SCM/DOX, might be promising in clinical systemic chemotherapy through intravenous injection.

Reduction-responsive polypeptide nanogel delivers antitumor drug for improved efficacy and safety

Chemotherapy plays an irreplaceable role in the treatment of various malignant tumors today. The traditional drug formulations lack of selectivity, cause serious damage to normal tissues, and can't achieve a desired therapeutic efficacy. For this situation, a facilely prepared reduction-responsive polypeptide nanogel was employed for targeting intracellular delivery of antitumor drug in this study. Doxorubicin (DOX) as a model drug was loaded into nanogel through a sequential dispersion and dialysis approach with a drug loading efficiency (DLE) of 56.8wt.%. The loading nanogel, i.e., NG/DOX, exhibited a medium hydrodynamic radius of 56.1±3.5nm, glutathione-accelerated DOX release, and efficient cellular uptake and proliferation inhibition. Moreover, NG/DOX exhibited upregulated intratumoral accumulation and improved antitumor efficacy toward HepG2 hepatoma-xenografted BALB/c nude mouse model compared with free drug. The enhanced tumor suppression of NG/DOX was further confirmed by the histopathological and immunohistochemical analyses. Furthermore, the excellent in vivo security of NG/DOX was systematically demonstrated by the variation detection of body weight, histopathological assay, levels of bone marrow cell micronucleus rate (BMMR) and white blood cells (WBCs), and detection of clinical parameters in corresponding organs and serum. With controllable large-scale preparation and fascinating properties in vitro and in vivo, the reduction-responsive polypeptide nanogel is revealed to exhibit great potential for on-demand intracellular delivery of antitumor drugs, and shows a good prospect for clinical chemotherapy.

STATEMENT OF SIGNIFICANCE

The traditional drug formulations lack of selectivity, cause serious damage to normal tissues, and can't achieve a desired therapeutic effect. For this situation, a facilely prepared reduction-responsive polypeptide nanogel is employed for targeting intracellular delivery of antitumor drug in this study. The laden nanogel keeps structural integrity and less drug release in the circulatory system after intravenous injection, releases the payload triggered by the intracellular high concentration of GSH, and exhibits the excellent tumor inhibition and security in vivo. Furthermore, the other hydrophobic antitumor drugs can also be on-demand delivered by the smart nanogel. All of the above advantages confirm the bright prospect of reduction-responsive nanogel on the road of malignancy chemotherapy.