Bioreducible Polymer Nanocarrier Based on Multivalent Choline Phosphate for Enhanced Cellular Uptake and Intracellular Delivery of Doxorubicin

Protein-Nonfouling and Cell-Binding Polysulfobetaine Inducing Fast Transcytosis for Tumor-Active Drug Delivery

Long blood circulation and fast cellular uptake are essential yet paradoxical requirements for efficient tumor-targeted drug delivery carriers. For instance, polyzwitterions, generally nonfouling to proteins and cells, have been extensively explored as long-circulating drug delivery carriers but suffer ultraslow cell internalization, making them inefficient in delivering drugs to cells. Protein-resistant yet cell membrane-binding polymers will simultaneously achieve long blood circulation and fast cellular internalization, but their designs are generally complicated, such as introducing cell-membrane binding groups. Here, it is shown that the N-alkyl chain length of zwitterionic poly(sulfobetaine) can be used to tune its affinity toward proteins and cell membranes. A poly(sulfobetaine) with a moderately long N-alkyl chain became cell membrane-philic while retaining protein resistance, leading to long blood circulation and fast cellular uptake, which further triggered efficient tumor cell transcytosis and intratumor penetration. Thus, its paclitaxel (PTX)-loaded micelles demonstrated potent antitumor efficacy in triple-negative breast cancer models. This study showcases a paradigm of designing polyzwitterions harmonizing long blood circulation and fast cellular uptake properties as tumor-active drug delivery carriers.

Enhanced Antigen Capture via Cholinephosphate-Mediated Cell Membrane Interactions to Improve In Situ Tumor Vaccines

Inadequate antigen capture and insufficient antigen-presenting cell (APC) activity at tumor sites limit the effectiveness of in situ vaccines. To address this, poly(glutamic acid-cholinephosphate) (pGluCP) is introduced as a polymer with cell membrane adhesion properties capable of capturing both water-soluble and insoluble membrane antigens from necrotic tumor cells while recruiting more APCs. The approach uses manganese-mineralized black phosphorus (MnBP) coated with pGluCP and αPD-1 antibodies to create the MnBP@pGluCP-αPD-1 complex for in situ vaccines. MnBP eradicates tumor cells via photothermal effects, releasing antigens, while Mn2⁺ ions activate the intracellular STING pathway, acting as an adjuvant. pGluCP captures these antigens, forming pathogen-mimicking micro-nanoparticles, leading to an in situ vaccine (MnBP@pGluCP/antigens) that co-localizes antigens and adjuvants. The αPD-1 antibody alleviates tumor-induced immune suppression, enhancing tumor cell-specific killing. This study demonstrates the potential of leveraging cholinephosphate-cell membrane interactions to improve antigen presentation efficiency, significantly bolstering the efficacy of in situ tumor vaccines and opening new avenues for advanced cancer immunotherapy.

pH responsive and zwitterionic micelle for enhanced cellular uptake and antitumor performance

The side effects of small molecule chemotherapeutic drugs (SMCD) have brought great pain to the cancer patients. Many nanodrug carriers can relieve the shortcomings of SMCD, but they have complex synthesis processes and lack biodegradability. To overcome both problems, we synthesized a pH responsive biodegradable zwitterionic molecules (EK-D) by linking zwitterionic polypeptide (EK7) and dodecyl acrylate through a simple click reaction. Subsequently, doxorubicin (DOX) was physically encapsulated within the EK-D micelles to produce EK-D-DOX micelles, and polyethylene glycol monooleate (POO) employed as a comparative group for the preparation of POO-DOX micelles. The results show that EK-D-DOX micelles have good aqueous stability and anti-protein non-specific adsorption performance at pH 7.4, but EK-D-DOX micelles aggregate under the condition of pH = 5.5 due to the biodegradability of EK-D. The tumor cell uptake rate of EK-D-DOX micelles is higher than that of POO-DOX micelles and free DOX, which makes EK-D-DOX micelles the highest cytotoxic. Additionally, EK-D-DOX micelles release more DOX in a slightly acidic environment than at pH 7.4, and the release of DOX reaches a significant cumulative value of 75.20 % under pH conditions of 5.5. More importantly, EK-D-DOX micelles exhibit superior in vivo tumor inhibitory efficacy compared to free DOX, resulting in a remarkable tumor inhibition rate of 95.7 %. EK-D-DOX micelles not only have lower biological toxicity to normal tissues than free DOX, but also have a longer blood circulation time in mice. The method of EK-D-DOX micelles preparation represents a new method to prepare biodegradable zwitterionic nanodrug.

Phosphocholine inhibits proliferation and reduces stemness of endometrial cancer cells by downregulating mTOR-c-Myc signaling

BACKGROUND

Endometrial cancer (EC) represents a serious health concern among women globally. Excessive activation of the protooncogene c-Myc (c-Myc) is associated with the proliferation and stemness of EC cells. Phosphocholine (PC), which is synthesized by choline kinase alpha (CHKA) catalysis, is upregulated in EC tumor tissues. The present study aimed to investigate the effect of PC accumulation on EC cells and clarify the relationship between PC accumulation and c-Myc activity in EC.

METHODS

The c-Myc and CHKA expression in EC tumor tissues were examined using immunohistochemistry. Cell Counting Kit-8 assay, colony formation assay, flow cytometry, western blotting, BrdU staining, and tumorsphere formation assay were used to assess the effect of PC accumulation on EC cells. The mechanism by which PC accumulation inhibits c-Myc was evaluated using RNA-sequencing. Patient-derived organoid (PDO) models were utilised to explore the preclinical efficacy of PC against EC cells.

RESULTS

PC accumulation suppressed EC cell proliferation and stemness by inhibiting the activation of the mammalian target of rapamycin (mTOR)-c-Myc signaling. PC accumulation promoted excessive reactive oxygen species production, which reduced the expression of GTPase HRAS. This, in turn, inhibited the mTOR-c-Myc axis and induced EC cell apoptosis. Finally, PC impeded proliferation and downregulated the expression of the mTOR-MYC signaling in EC PDO models.

CONCLUSIONS

PC accumulation impairs the proliferation ability and stem cell characteristics of EC cells by inhibiting the activated mTOR-c-Myc axis, potentially offering a promising strategy to enhance the efficacy of EC clinical therapy through the promotion of PC accumulation in tumor cells.

Oral Delivery of Photopolymerizable Nanogels Loaded with Gemcitabine for Pancreatic Cancer Therapy: Formulation Design, and in vitro and in vivo Evaluations

Background

Gemcitabine (GEM) faces challenges of poor oral bioavailability and extensive first-pass metabolism. Currently, only injectable formulations are available for clinical use. Hence, there is an urgent demand for the development of advanced, efficacious, and user-friendly dosage forms to maintain its status as the primary treatment for pancreatic ductal adenocarcinoma (PDAC). Nanogels (NGs) offer a novel oral drug delivery system, ideal for hydrophilic compounds like GEM. This study aims to develop NGs tailored for GEM delivery, with the goal of enhancing cellular uptake and gastrointestinal permeability for improved administration in PDAC patients.

Methods

We developed cross-linked NGs via photopolymerization of methacryloyl for drug delivery of GEM. We reveal characterization, cytotoxicity, and cellular uptake studies in Caco-2 and MIA PaCa-2 cells. In addition, studies of in vitro permeability and pharmacokinetics were carried out to evaluate the bioavailability of the drug.

Results

Our results show NGs, formed via photopolymerization of methacryloyl, had a spherical shape with a size of 233.91±7.75 nm. Gemcitabine-loaded NGs (NGs-GEM) with 5% GelMA exhibited efficient drug loading (particle size: 244.07±19.52 nm). In vitro drug release from NGs-GEM was slower at pH 1.2 than pH 6.8. Cellular uptake studies indicated significantly enhanced uptake in both MIA PaCa-2 and Caco-2 cells. While there was no significant difference in GEM's AUC and Cmax between NGs-GEM and free-GEM groups, NGs-GEM showed markedly lower dFdU content (10.07 hr∙μg/mL) compared to oral free-GEM (19.04 hr∙μg/mL) after oral administration (p<0.01), highlighting NGs' efficacy in impeding rapid drug metabolism and enhancing retention.

Conclusion

In summary, NGs enhance cellular uptake, inhibit rapid metabolic degradation of GEM, and prolong retention after oral administration. These findings suggest NGs-GEM as a promising candidate for clinical use in oral pancreatic cancer therapy.

Preparation, stability, and in vitro transport of soybean protein-based diosgenin nanoemulsions

Soybean protein isolate (SPI)-stabilized nanoemulsions (NEs) were formulated to encapsulate diosgenin (DIO) to enhance its water solubility and bioavailability. The influence of DIO concentrations on NEs' properties was investigated, and their environmental stability and cell permeability were also assessed. Results demonstrated that DIO significantly affected all the physicochemical properties of NEs. NEs with 1.0 mg/mL of DIO exhibited smaller droplet size (209 nm), lower polydispersity index (0.17), and higher stability coefficient (95.8 %). Furthermore, DIO-SPI NEs displayed better stability under appropriate pH (<4 or > 5), NaCl concentrations (≤0.3 M), temperatures (≤60 °C), and freeze-thaw cycles (≤2), as well as storage at 4 °C. Moreover, encapsulating DIO in NEs reduced its toxicity towards cells and enhanced its transport efficiency, which reached 3.16 ∼ 4.87 × 10-6. These findings highlight the potential of SPI-based NEs as a promising carrier for the efficient delivery of DIO.

Reversible, Covalent DNA Condensation Approach Using Chemical Linkers for Enhanced Gene Delivery

Nonviral gene delivery has emerged as a promising technology for gene therapy. Nonetheless, these approaches often face challenges, primarily associated with lower efficiency, which can be attributed to the inefficient transportation of DNA into the nucleus. Here, we report a two-stage condensation approach to achieve efficient nuclear transport of DNA. First, we utilize chemical linkers to cross-link DNA plasmids via a reversible covalent bond to form smaller-sized bundled DNA (b-DNA). Then, we package the b-DNA into cationic vectors to further condense b-DNA and enable efficient gene delivery to the nucleus. We demonstrate clear improvements in the gene transfection efficiency in vitro, including with 11.6 kbp plasmids and in primary cultured neurons. Moreover, we also observed a remarkable improvement in lung-selective gene transfection efficiency in vivo by this two-stage condensation approach following intravenous administration. This reversible covalent assembly strategy demonstrates substantial value of nonviral gene delivery for clinical therapeutic applications.

Oral membrane-biomimetic nanoparticles for enhanced endocytosis and regulation of tumor-associated macrophage

Enterocyte uptake with high binding efficiency and minor endogenous interference remains a challenge in oral nanocarrier delivery. Enterocyte membrane-biomimetic lipids may universally cooperate with endogenous phosphatidyl choline via a biorthogonal group. In this study, we developed a sophorolipid-associated membrane-biomimetic choline phosphate-poly(lactic-co-glycolic) acid hybrid nanoparticle (SDPN). Aided by physical stability in the gastrointestinal tract and rapid mucus diffusion provided by association with sophorolipid, these nanoparticles show improved endocytosis, driven by dipalmitoyl choline phosphate-phosphatidyl choline interaction as well as its optimized membrane fluidity and rigidity. Luteolin- and silibinin-co-loaded with SDPN alleviated breast cancer metastasis in 4T1 tumor-bearing mice by regulating the conversion of tumor-associated M2 macrophages into the M1 phenotype and reducing the proportion of the M2-phenotype through co-action on STAT3 and HIF-1α. In addition, SDPN reduces angiogenesis and regulates the matrix barrier in the tumor microenvironment. In conclusion, this membrane-biomimetic strategy is promising for improving the enterocyte uptake of oral SDPN and shows potential to alleviate breast cancer metastasis.

Zwitterionic doxorubicin loaded micelles based on polyethyleneimine for enhanced antitumor therapy in vivo

Zwitterionic groups of doxorubicin loaded micelles enhanced their antitumor performance in vivo.

Construction of Folate-Conjugated and pH-Responsive Cell Membrane Mimetic Mixed Micelles for Desirable DOX Release and Enhanced Tumor-Cellular Target

Smart multifunctional polymeric micelles are in urgent demand for future cancer diagnosis and therapy. In this paper, doxorubicin (DOX)-loaded folic acid (FA)-targeting and pH-responsive cell membrane mimetic mixed micelles of P(DMAEMA-co-MaPCL) (PCD) and FA-P(MPC-co-MaPCL) (PMCF) (mass ratio 5/5) were prepared by a dialysis method. The micelle size, morphology, X-ray powder diffraction (XRD), pH responsiveness, in vitro DOX release, cytotoxicity, and cellular uptake were studied in detail. The results indicated that DOX could be efficiently loaded into mixed micelles (PDMCF micelles), and the DOX-loaded mixed micelles (DOX@PDMCF micelles) exhibited a size of 150 nm and pH-responsive DOX release in an extended period. Furthermore, the DOX@PDMCF micelles could efficiently suppress the proliferation of tumor cells, HeLa and MCF-7 cells. Our data suggest that the DOX@PDMCF micelles have the potential to be applied in tumor therapy, especially for treating various folate receptor overexpressed tumors.

Phosphorylcholine zwitterionic shell-detachable mixed micelles for enhanced cancerous cellular uptakes and increased DOX release

To further enhance the cancerous cellular uptakes and increase the drug release of the drug loaded micelles, herein, we fabricated a series of mixed micelles with different mass ratios using two amphiphilic copolymers P(DMAEMA-co-MaPCL) and PCL-SS-PMPC. The mixed micelles showed a prolonged circulation time due to the zwitterionic shells in a physiological environment (pH 7.4). In addition, because of the protonation of tertiary amine groups in PDMAEMA and the breakage of the disulfide bond in PMPC-SS-PCL in a tumor microenvironment, the mixed micelles aggregated, which led to enhanced cancerous cellular penetration and increased DOX release. Moreover, cytotoxicity assay showed that the mixed micelles had good biocompatibility to L929, HeLa and MCF-7 cells, even at a concentration of up to 1 mg mL^-1. Furthermore, enhanced antitumour activity and cellular uptake of HeLa and MCF-7 cells were detected after loading with DOX, which was determined by confocal laser scanning microscopy (CLSM) and flow cytometry (FC), especially for the DOX@MIX 3 micelles (20% mass ratio of the P(DMAEMA-co-MaPCL)). Therefore, the mixed strategy provides a simple and efficient ways to promote anticancer drug delivery.

Trojan Horse Delivery of Spherical Nucleic Acid Probes into the Cytoplasm for High-Fidelity Imaging of MicroRNAs

We report a Trojan horse strategy to efficiently deliver the spherical nucleic acid probes (namely, nanoflares) into the cytoplasm for microRNA (miRNA) imaging with high fidelity, breaking through the cytoplasmic transport dilemma of RNA probes in living cells. The nanoflare is encapsulated into a "Trojan horse" consisting of zwitterionic choline phosphates (CPs) and acid-degradable crosslinkers; the former effectively promotes cell uptake and the latter triggers instantaneous liberation of the nanoflare probes from the lysosome to the cytoplasm. The exposed nanoflares in the cytoplasm can be lightened up by the target miRNAs specifically. Compared with the conventional nanoflares as well as the improved ones in previous reports, the "Trojan horse" nanoflares avoid nuclease degradation and thiol displacement during the delivery process, providing unprecedentedly high accuracy for intracellular miRNA imaging.

Polylactic acid film surface functionalized by zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] with improved biocompatibility

Polylactic acid (PLA) is a non-toxic, biodegradable biological material that is widely used in tissue engineering and regenerative medicine. PLA is easy to adsorb non-specific proteins and lacks cell adhesion after implantation. Choline phosphate (CP) is a novel zwitterion with a reverse structure of phosphate choline (PC) on the cell membrane that can form a specific "CP-PC" interaction to promote cell adhesion. In our previous work, modification of choline phosphate polymers (PMCP) onto the PLA film surface improved the hydrophilicity and degradation properties. In this study, we further investigated the biocompatibility of PLA-PMCP films from protein adsorption, cell adhesion and proliferation, bacterial adhesion, blood compatibility, and inflammation in vivo. The PLA-PMCP surface can resist protein adsorption and bacterial adhesion due to the anti-fouling properties of the zwitterion PMCP. Meanwhile, the PLA-PMCP surface promotes the adhesion and proliferation of BMSCs due to the specific "CP-PC" effect. In addition, the PLA-PMCP film has good blood compatibility as well as the PLA film. During in vivo experiments, biocompatibility was improved and the inflammatory response and immune rejection of PLA-PMCP films were reduced compared to those of the original PLA film. Therefore, the PMCP-modified PLA film resists protein adsorption and bacterial adhesion, promotes cell adhesion and proliferation, and has good hemocompatibility and histocompatibility. This brings a significant potential for application in the fields of tissue engineering and regenerative medicine.

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

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

Multifunctional Biomedical Materials Derived from Biological Membranes

The delicate structure and fantastic functions of biological membranes are the successful evolutionary results of a long-term natural selection process. Their excellent biocompatibility and biofunctionality are widely utilized to construct multifunctional biomedical materials mainly by directly camouflaging materials with single or mixed biological membranes, decorating or incorporating materials with membrane-derived vesicles (e.g., exosomes), and designing multifunctional materials with the structure/functions of biological membranes. Here, the structure-function relationship of some important biological membranes and biomimetic membranes are discussed, such as various cell membranes, extracellular vesicles, and membranes from bacteria and organelles. Selected literature examples of multifunctional biomaterials derived from biological membranes for biomedical applications, such as drug- and gene-delivery systems, tissue-repair scaffolds, bioimaging, biosensors, and biological detection, are also highlighted. These designed materials show excellent properties, such as long circulation time, disease-targeted therapy, excellent biocompatibility, and selective recognition. Finally, perspectives and challenges associated with the clinical applications of biological-membrane-derived materials are discussed.

Zwitterionic PMCP-functionalized titanium surface resists protein adsorption, promotes cell adhesion, and enhances osteogenic activity

Titanium (Ti) has excellent biocompatibility and corrosion resistance and is widely used as a biomedical material for orthopedic implants. However, the bare Ti surface limits cell adhesion without biological activity and promotes unnecessary protein adsorption, which can activate the coagulation pathway with blood-contacting devices. To improve the antifouling and biological activity of Ti, zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (PMCP) was used to modify the Ti surface via surface-initiated atom transfer radical polymerization. The Ti-PMCP surface reduced bovine serum albumin and fibrinogen adsorption owing to the zwitterionic antifouling property. Ti-PMCP is involved in the unique interaction between PMCP on the Ti surface and phosphate choline on cell membranes, and therefore, the Ti-PMCP surface can promote the adhesion and proliferation of MC3T3-e1 cells and bone marrow mesenchymal cells (BMSCs). In addition, the Ti-PMCP surface was effective in promoting the osteogenic differentiation of MC3T3-e1 cells and BMSCs because the phosphate group in MCP can stimulate osteogenic signaling pathways. Therefore, the PMCP-modified Ti surface can resist protein adsorption and promote the adhesion, proliferation, and differentiation of osteoblast-related cells and has great potential in bone tissue engineering.

Synthesis and Characterization of Folate-Modified Cell Membrane Mimetic Copolymer Micelles for Effective Tumor Cell Internalization

The inefficient targeting and phagocytic clearance of nanodrug delivery systems are two major obstacles in cancer therapy. Here, inspired by the special properties of zwitterionic polymers and folic acid (FA), a partly biodegradable copolymer of FA-modified poly(ε-caprolactone) block poly(2-methacryloxoethyl phosphorylcholine), PCL-b-PMPC-FA, was synthesized via atom transfer radical polymerization (ATRP) and click reaction. Non-FA-modified copolymer PCL-b-PMPC was also synthesized as a control. The hydrodynamic diameter of the PCL-b-PMPC-FA micelles is 158 nm (PDI 0.261), slightly larger than that of the PCL-b-PMPC micelles (139 nm, PDI 0.242). The drug doxorubicin (DOX) could be entrapped in the micelles, and as the pH decreased from 7.4 to 5.0, DOX release (in vitro) was accelerated. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated that both the PCL-b-PMPC and the PCL-b-PMPC-FA micelles showed low toxicity to L929, HeLa, and MCF-7 cells. In addition, the DOX-loaded micelles, PCL-b-PMPC/DOX and PCL-b-PMPC-FA/DOX micelles, exhibited low toxicity to L929 cells but high toxicity to HeLa and MCF-7 cells, especially the PCL-b-PMPC-FA/DOX micelles. HeLa and MCF-7 cell uptakes of the PCL-b-PMPC-FA/DOX micelles were 4.8 and 4.5 times higher than that of the PCL-b-PMPC/DOX micelles, respectively. Therefore, PCL-b-PMPC-FA micelles have great potential for developing drug delivery systems with extended circulation times and tumor-targeting properties.

Targeted liposomal drug delivery: a nanoscience and biophysical perspective

Liposomes are a unique platform for drug delivery, and a number of liposomal formulations have already been commercialized. Doxil is a representative example, which uses PEGylated liposomes to load doxorubicin for cancer therapy. Its delivery relies on the enhanced permeability and retention (EPR) effect or passive targeting. Drug loading can be achieved using both standard liposomes and also those containing a solid core such as mesoporous silica and poly(lactide-co-glycolide) (PLGA). Developments have also been made on active targeted delivery using bioaffinity ligands such as small molecules, antibodies, peptides and aptamers. Compared to other types of nanoparticles, the surface of liposomes is fluid, allowing dynamic organization of targeting ligands to achieve optimal binding to cell surface receptors. This review article summarizes development of liposomal targeted drug delivery systems, with an emphasis on the biophysical properties of lipids. In both passive and active targeting, the effects of liposome size, charge, fluidity, rigidity, head-group chemistry and PEGylation are discussed along with recent examples. Most of the examples are focused on targeting tumors or cancer cells. Finally, a few examples of commercialized formulations are described, and some future research opportunities are discussed.

Choline phosphate lipid insertion and rigidification of cell membranes for targeted cancer chemo-immunotherapy

To prevent tumor reproduction and metastasis, a method to modify the membranes of cancer cells was designed to suppress their vitality. A phosphatidyl choline reversed choline phosphate lipid (CP-Lip) was synthesized and modified with a PD-L1 antibody (CP-αPDL). Drug-loaded nanoparticles of CP-Lip/CP-αPDL (Dox@tCP-Lipos) could be selectively attached to melanoma cells, thus causing CP-Lip to be inserted and to interact strongly with the cell membrane, which largely reduced the fluidity and functionality of the membrane. As a result, the metabolism, reproduction, and migration of melanoma cells were proved to be weakened by CP-Lip and the tumor was 100% suppressed after treatment with Dox@tCP-Lipos.

Cell-Membrane-Targeted Drug Delivery System Based on Choline-Phosphate-Functionalized β-Cyclodextrin

In this study, a novel cyclodextrin derivative, i.e., zwitterionic choline phosphate (CP)-functionalized β-cyclodextrin (CP-β-CD) is successfully synthesized by click chemistry reaction. CP-β-CD has excellent cell-membrane-targeted ability because of the CP group can bind to phosphate choline (PC) in the cell membrane and promote the cellular uptake. Due to the introduction of CP group on β-CD, it disrupts the hydrogen network between natural β-CD molecules. Meanwhile, the water solubility of CP-β-CD is improved dramatically to 816 mg mL^-1 , which is 440 times as that of unmodified β-CD. Apatinib, a small molecular inhibitor, is used as a model of hydrophobic drug and loaded into CP-β-CD to study the solubilization effect and the anti-angiogenisis activity. In addition, the cytotoxicity of CP-β-CD is also studied, and it is demonstrated that CP-β-CD is nontoxic. These results indicate that the apatinib can be transported into cell interior and play an excellent anti-angiogenisis activity after being loaded into CP-β-CD drug delivery system. This work suggests that the water soluble CP-β-CD with excellent cell internalization efficiency has a potential application prospect in the field of drug delivery.

Computational insights of two‐dimensional infrared spectroscopy under electric fields in phosphorylcholine

Influence of static electric field in biological cells causes electroporation, which results in the increase of permeability of the cells and phospholipid bilayer. However, the precise mode of action of electric fields on phospholipid bilayer and their quantum mechanics are still unclear. Therefore, to understand the quantum‐based biological effect, we aimed to study two‐dimensional infrared (2D‐IR) spectra‐adopted quantum mechanics/molecular mechanics (QM/MM) simulations under the influence of static electric fields on Phosphorylcholine, an important component in phospholipid membrane. Initially, QM/MM studies were performed under the influence of electric field, ranging from −1.543 to 1.028 V/nm. A multilayer ONIOM model (in combination with DFT/B3LYP/6‐31G [d, p] and DREIDING force fields) was used to obtain 2D‐IR simulated spectra to calculate electrostatic interaction in the biological system. The results demonstrated that the phosphate group played an important role on α‐rotation in LUMO and the chlorine atom had a major contribution in HOMO. In addition, decreased number of hydrogen bonds demonstrated that uncoupling reaction of the P‐O stretching vibrations while the electric field was −1.542 V/nm. Moreover, we observed that the electric field is −1.028 V/nm, there is no rotational isomerization in phosphorylcholine. We concluded that the static electric fields significantly affect the anharmonic frequencies, vibration coupling and the structure of the phosphorylcholine.

Poly(ethylene glycol)-sheddable reduction-sensitive polyurethane micelles for triggered intracellular drug delivery for osteosarcoma treatment

BACKGROUND

The survival rate of osteosarcoma therapy still lags behind overall cancer therapies due to the intrinsic or acquired drug resistance. Developing novel drug delivery systems that may overcome drug resistance would greatly facilitate osteosarcoma therapy.

METHODS

Poly(ethylene glycol) (PEG)-sheddable reduction-sensitive polyurethane (SS-PU-SS-PEG) was synthesized using a disulfide-containing polycaprolactone diol as the hydrophobic block and a cystamine-functionalized PEG as the hydrophilic block. SS-PU-SS-PEG micelles were then prepared to load the anti-tumor drug Doxorubicin (DOX) in order to achieve triggered intracellular drug delivery to improve the efficacy of osteosarcoma therapy.

RESULTS

When DOX was used as a model drug, the drug-loaded SS-PU-SS-PEG micelles were about 82∼94 nm in diameter and exhibited good stability in phosphate buffer saline (PBS). The micelles could release about 80% DOX in a quantitative fashion within 5 hours under a reductive environment. The intracellular drug release of DOX-loaded SS-PU-SS-PEG micelles increased upon incubation with Saos-2 cells in vitro. The micelles had good biocompatibility. In vitro, DOX-loaded SS-PU-SS-PEG micelles showed significant antitumor activity toward Saos-2 cells, which was close to that of free DOX. In vivo, DOX-loaded SS-PU-SS-PEG micelles exhibited better antitumor activity than free DOX.

CONCLUSION

Findings from this study suggest that the SS-PU-SS-PEG micelles could achieve well-controlled triggered drug release in a reduction environment and could therefore improve the antitumor efficacy of osteosarcoma therapies.

TRANSLATION POTENTIAL OF THIS ARTICLE

In this study we developed PEG-sheddable reduction-sensitive polyurethane micelles (SS-PU-SS-PEG), which were able to achieve well-controlled triggered release of anti-tumor drug Doxorubicin (DOX) in an intracellular reduction environment. DOX-loaded SS-PU-SS-PEG micelles markedly improved the antitumor efficacy in a Saos-2 cells-bearing xenograft tumor model. Therefore, such micelles might be used as a novel drug delivery system for osteosarcoma treatment.

Hydrogen Peroxide and Glutathione Dual Redox-Responsive Nanoparticles for Controlled DOX Release

Polymer nanoparticulate drug delivery systems that respond to reactive oxygen species (ROS) and glutathione (GSH) simultaneously at biologically relevant levels hold great promise to improve the therapeutic efficacy to cancer cells with reduced side effects of chemo drugs. Herein, a novel redox dual-responsive amphiphilic block copolymer (ABP) that consists of a hydrophilic poly (ethylene oxide) block and a hydrophobic block bearing disulfide linked phenylboronic ester group as pendant is synthesized, and the DOX loaded nanoparticles (BSN-DOX) based on ABPs with varied hydrophobic block length are fabricated for DOX delivery. The self-immolative leaving reaction of phenylboronic ester triggered by extracellular ROS and the cleavage of disulfide linkages induced by intracellular GSH both lead to rapid DOX release from BSN-DOX, resulting in an on-demand DOX release. Moreover, BSN-DOX show better tumor inhibition and lower side effects in vivo compared with free drug.

A Multi-crosslinking Nanocapsule-Based Serial-Stimuli-Responsive Leakage-Free Drug-Delivery System In Vitro

As some stimuli utilized in conventional drug delivery systems can also be found in normal cells, it is inevitable that encapsulated drugs escape from carriers into normal cells. Based on mutual interactions among proteins, polyphenol compounds, and metal ions, we developed a serial-stimuli-responsive drug delivery system. With multi-crosslinking structure, nanocapsules can maintain the integrity of the framework, even with a certain amount of stimuli present, and eventually reach tumor cells to initiate apoptosis, and protect normal cells from being damaged. Meanwhile, the fluorescence of DOX will be quenched when encapsulated in nanocapsules. This property means that the DOX that is released from nanocapsules can be monitored in real-time based on the recovery of fluorescence. These versatile nanocapsules exhibit great potentials to treat cancer.

Zwitterionic PMCP-Modified Polycaprolactone Surface for Tissue Engineering: Antifouling, Cell Adhesion Promotion, and Osteogenic Differentiation Properties

Biodegradable polycaprolactone (PCL) has been widely applied as a scaffold material in tissue engineering. However, the PCL surface is hydrophobic and adsorbs nonspecific proteins. Some traditional antifouling modifications using hydrophilic moieties have been successful but inhibit cell adhesion, which is not ideal for tissue engineering. The PCL surface is modified with bioinspired zwitterionic poly[2-(methacryloyloxy)ethyl choline phosphate] (PMCP) via surface-initiated atom transfer radical polymerization to improve cell adhesion through the unique interaction between choline phosphate (CP, on PMCP) and phosphate choline (PC, on cell membranes). The hydrophilicity of the PCL surface is significantly enhanced after surface modification. The PCL-PMCP surface reduces nonspecific protein adsorption (e.g., up to 91.7% for bovine serum albumin) due to the zwitterionic property of PMCP. The adhesion and proliferation of bone marrow mesenchymal stem cells on the modified surface is remarkably improved, and osteogenic differentiation signs are detected, even without adding any osteogenesis-inducing supplements. Moreover, the PCL-PMCP films are more stable at the early stage of degradation. Therefore, the PMCP-functionalized PCL surface promotes cell adhesion and osteogenic differentiation, with an antifouling background, and exhibits great potential in tissue engineering.

Hydrogen-Bond Cyclization Programming of Ultrasensitive Esters and Its Application in Gene Delivery

The ester bond as a universal linker has recently been applied in gene delivery systems owing to its efficient gene release by electrostatic repulsion after its cleavage. However, the ester bond is nonlabile and is difficult to cleave in cells. This work reports a method in which a secondary amine was introduced to the β-position of the ester bond to generate a hydrogen-bond cyclization (HBC) structure that can make the ester bond hydrolysis ultrafast. A series of molecules comprising ultrasensitive esters that can be activated by H₂ O₂ were synthesized, and it was found that those able to form an HBC structure showed complete ester hydrolysis within 5 h in both water and phosphate-buffered saline solution, which was several times faster than other methods reported. Then, a series of amphiphilic poly(amidoamine) dendrimers were constructed, comprising the ultrasensitive ester groups for gene delivery; it was found that they could effectively release genes under quite a low concentration of H₂ O₂ (<200 μm) and transport them into the nucleus within 2 h in Hela cells with high safety. Their gene transfection efficiencies were higher than that of PEI_25k . The results demonstrated that the hydrogen-bond-induced ultrasensitive esters could be powerfully applied to construct gene delivery systems.

Multivalent nanoparticles for personalized theranostics based on tumor receptor distribution behavior

It is acknowledged that the targeting ability of multivalent ligand-modified nanoparticles (MLNs) strongly depends on the ligand spatial presentation determined by ligand valency. However, the receptor overexpression level varies between different types or stages of tumors. Thus, it is essential to explore the influence of ligand valency on the targeting ability of MLNs to tumors with different levels of receptor overexpression. In this study, a dual-acting agent raltitrexed was used as a ligand to target the folate receptor (FR). Different copies of the raltitrexed-modified multivalent dendritic polyethyleneimine ligand cluster PRn (n = 2, 4, and 8) were conjugated onto magnetic nanoparticles to form multivalent magnetic NPs (MMNs) with different valences. The in vitro studies demonstrated that Fe-PR4 was the most effective valency in the treatment of high FR overexpressing KB cells with a decentralized receptor distribution, owing to the fact that Fe-PR2 was negative in statistical rebinding and Fe-PR8 could induce steric hindrance in the limited binding area. Instead, in moderate FR overexpressing HeLa cells with clustered receptor display, the extra ligands on Fe-PR8 would facilitate statistical rebinding more beneficially. Furthermore, in in vivo tumor inhibition and targeted magnetic resonance imaging (MRI) of KB tumors and another moderate FR expressing H22 tumor, similar results were obtained with the cell experiments. Overall, the optimizable treatment effect of Fe-PRn by modulating the ligand valency based on the overexpressing tumor receptor distribution behavior supports the potential of Fe-PRn as a nanomedicine for personalized theranostics.

Intermolecular Interaction of Polymer Brushes Containing Phosphorylcholine and Inverse-Phosphorylcholine

Choline phosphate (CP) is a phosphobetaine-type zwitterionic functional group, referred to as inverse phosphorylcholine (PC) due to the reverse orientation of a positively charged quaternary amine and anionic phosphate in contrast to PC lipids in nature. The A unique dipole paring between CP and PC groups has attracted much attention in the biointerface research field. Herein, to evaluate the molecular interaction between the CP and PC groups in water, force-distance curve measurements using scanning probe microscopy (SPM) with a PC-group-functionalized cantilever was carried out on the surface of polymer brushes bearing the CP groups. Three types of methacrylate monomers bearing CP with ethyl (Et), methoxyethyl (MOE), and isopropyl (iPr) phosphates were synthesized in 42-71% yields, and polymerized by surface-initiated atom transfer radical polymerization to form polymer brushes on silicon wafers. The surface free energy of CP-polymer brushes with Et, MOE, and iPr was estimated to be 64.0, 61.4, and 57.4 mN m^-1, respectively, based on contact angle measurements. Force-distance curve measurements of polymer brushes having a CP group was conducted in water at 25 °C by SPM using a spherical probe produced by attaching a silica particle (SiP; d = 25 μm) covered with PC or CP groups to a tipless cantilever. Adhesion force larger than 14 nN was observed between the CP-polymer brushes and PC-SiP, whereas PC-polymer brushes revealed extremely low adhesion force of less than 0.6 nN with PC-SiP and propylsilane-modified SiP. The specific attractive molecular interaction between CP and PC groups was quantitatively evaluated.

Folate-Conjugated Cell Membrane Mimetic Polymer Micelles for Tumor-Cell-Targeted Delivery of Doxorubicin

Tumor-targeting nano-drug-delivery systems hold great potential to improve the therapeutic efficacy and alleviate the side effects of cancer treatments. Herein, folic acid (FA)-decorated amphiphilic copolymer of FA-P(MPC- co-MaPCL) (MPC: 2-methacryloxoethyl phosphorylcholine, MaPCL: poly(ε-caprolactone) macromonomer) is synthesized and its micelles are fabricated for doxorubicin (DOX) delivery. And non-FA-decorated P(MPC- co-MaPCL) micelles are used as the control. Dynamic light scattering and scanning electron microscopy measurements reveal that FA-P(MPC- co-MaPCL) and P(MPC- co-MaPCL) micelles are spherical with average diameters of 140 and 90 nm, respectively. The evaluation in vitro demonstrates that the blank micelles are nontoxic, while DOX-loaded FA-P(MPC- co-MaPCL) micelles show significant cytotoxicity to HeLa cells and slight cytotoxicity to L929 cells. Moreover, the cellular uptake of DOX-loaded FA-P(MPC- co-MaPCL) micelles in HeLa cells are 4.3-fold and 1.7-fold higher than that of DOX-loaded P(MPC- co-MaPCL) micelles and free DOX after 6 h of incubation, respectively. These results indicate the great potential of this system in anticancer target drug-delivery applications.

Zwitterionic shielded polymeric prodrug with folate-targeting and pH responsiveness for drug delivery

Zwitterionic polymers are a class of polymers that acts as both Lewis base and Lewis acid in solution. These polymers not only have excellent properties of hydration, anti-bacterial adhesion, charge reversal and easy chemical modification, but also have characteristics of long-term circulation and suppress nonspecific protein adsorption in vivo. Here, we describe a novel folate-targeted and acid-labile polymeric prodrug under the microenvironment of tumor cells, abbreviated as FA-P(MPC-co-PEGMA-BZ)-g-DOX, which was synthesized via a combination of reversible addition-fragmentation chain transfer (RAFT) copolymerization, Schiff-base reaction, Click chemistry, and a reaction between the amine group of doxorubicin (DOX) and aldehyde functionalities of P(MPC-co-PEGMA-BZ) pendants, wherein MPC and PEGMA-BZ represent 2-(methacryloyloxy)ethyl phosphorylcholine and polyethylene glycol methacrylate ester benzaldehyde, respectively. The polymeric prodrug could self-assemble into nanoparticles in an aqueous solution. The average particle size and morphologies of the prodrug nanoparticles were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. We also investigated the in vitro drug release behavior and observed rapid prodrug nanoparticle dissociation and drug release under a mildly acidic microenvironment. The methyl thiazolyl tetrazolium (MTT) assay verified that the P(MPC-co-PEGMA-BZ) copolymer possessed good biocompatibility and the FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticles showed higher cellular uptake than those prodrug nanoparticles without the FA moiety. The results of cytotoxicity and the intracellular uptake of non-folate/folate targeted prodrug nanoparticles further confirmed that FA-P(MPC-co-PEGMA-BZ)-g-DOX could be efficiently accumulated and rapidly internalized by HeLa cells due to the strong interaction between multivalent phosphorylcholine (PC) groups and cell membranes. This kind of multifunctional FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticle with combined target-ability and pH responsiveness demonstrates promising potential for cancer chemotherapy.

Light-Induced Hypoxia-Triggered Living Nanocarriers for Synergistic Cancer Therapy

Living drug delivery system has been proposed as new concept materials because it is able to communicate with biological system, sense subtle changes in body microenvironment caused by disease, and then make rapid response to cure in the early stage of disease. Herein, taking full advantage of the tumor hypoxia physiology and successive effects of photodynamic therapy (PDT), we designed a new living delivery system via combining the PDT and hypoxia-responsive chemotherapy, abbreviated as Ce6-PEG-Azo-PCL. Then, according to the fact that oxygen can be converted into reactive oxygen species during irradiation of the photosensitizer, tumor cells could be killed after the poly(ethylene glycol) (PEG) conjugated photosensitizer chlorine e6 was irradiated at the tumor site. What is more, the continuous consumption of oxygen could further amplify the hypoxia condition of tumor and trigger the disassembly of hypoxia-responsive azobenzene bridges at the tumor site to release loaded chemotherapeutics drugs doxorubicin. The ongoing collaboration with PDT and hypoxia-responsive chemotherapy provided an integrated therapeutic effect in vitro and in vivo to suppress tumor growth.