Choline phosphate lipid as an intra-crosslinker in liposomes for drug and antibody delivery under guard.

Liposomes are used to deliver therapeutics in vivo because of their good biocompatibility, efficient delivery, and ability to protect the therapeutics from degradation. However, the instability of liposomes will cause the therapeutics to lose protection and become ineffective. To deliver therapeutics to the target under guard, we synthesized and used a bio-membrane mimetic choline phosphate lipid (CP-lip) to intra-crosslink liposomes to highly improve their stability. We found that when the ratio of PC-lip to CP-lip is 1 : 2, the intra-crosslinked liposome (PC-CP-lipo) showed higher stability, better biocompatibility and improved anti-protein adsorption than other common liposomes. We used doxorubicin (Dox) loaded PC-CP-lipo to treat melanoma and the tumor inhibition ratio could reach 86.3%. After the combined Dox@PC-CP-lipo treatment with PD-L1 antibody to block the immune checkpoints, the tumor suppression rate could reach 94.4%, and 60% of the mice did not suffer from tumor rechallenge. The method of using a CP-lip to intra-crosslink liposomes is applicable to all liposomes, solving the key problem of liposome disintegration, thus enhancing the protection of drugs and antibodies by liposomes in vivo.

Infrared Responsive Choline Phosphate Lipids for Synergistic Cancer Therapy.

Choline phosphate lipids have been designed and developed as new-generation zwitterionic nanocarriers with excellent biocompatibility and bioorthogonality to provide a more programmable performance for cancer therapy. However, there is a lack of spatiotemporal and reversible control for drug release at target tumor cells, which can lead to severe adverse effects to normal tissue and discounted treatment outcome. Here, light-inducible Lip-cRGDfk/ICG/Dox liposomes were developed for synergistic cancer therapy. ICG can effectively convert light energy into selective heating in a local environment upon laser irradiation, thus inducing thermal ablation of tumor cells, and further reversibly trigger the spatiotemporal release of anticancer drugs (Dox) at tumor cells due to the conformation transformation of CP lipids to synergistically kill tumor cells. That Lip-cRGDfk/ICG/Dox exhibited a significant improvement for breast cancer therapy in vitro and in vivo is also demonstrated, thus it can serve as an efficient platform to noninvasively and spatiotemporally control the activation of cytotoxicity at tumor cells for precision cancer therapy.

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.

Highly Tough, Stretchable, Self-Adhesive and Strain-Sensitive DNA-Inspired Hydrogels for Monitoring Human Motion.

Hydrogels used as strain sensors often rely on splicing tapes to attach them to surfaces, which causes much inconvenience. Therefore, to develop strain sensor hydrogels that possess both good mechanical properties and self-adhesion is still a great challenge. Inspired by the multiple hydrogen bonding interactions of nucleobases in DNA, we designed and synthesized a series of hydrogels PAAm-GO-Aba/Tba/Aba+Tba comprising polyacrylamide (PAAm), graphene oxide (GO), acrylated adenine and thymine (Aba and Tba). The introduction of nucleobases helps hydrogels to adhere to various substrates through multiple hydrogen-bonding interactions. It has also been found that the adhesive strength of hydrogels with nucleobases for hogskin increased to 2.5 times that of those without nucleobases. Meanwhile, these hydrogels exhibited good dynamic mechanical and self-recovery properties. They can be directly attached to human skin as strain sensors to monitor the motions of finger, wrist, and elbow. Electrical tests indicate that they give precise real-time monitoring data and exhibit good strain sensitivity and electrical stability. This work provides a promising basis from which to explore the fabrication of tough, self-adhesive, and strain-sensitive hydrogels as strain sensors for applications in wearable devices and healthcare monitoring.

Aza-crown ether locked on polyethyleneimine: solving the contradiction between transfection efficiency and safety during in vivo gene delivery.

We proposed a method using an aza-crown ether derivative to lock a hyperbranched polyethyleneimine, which endows the PEI25k with tumor targeting ability, anti-serum ability and extended circulation in the blood meanwhile retaining the high gene complexation and high transfection efficiency. The method we proposed here simultaneously endows cationic materials with high transfection efficiency and high safety, which greatly pushed the cationic materials to be applied in in vivo gene delivery.

Redox-Responsive Multifunctional Polypeptides Conjugated with Au Nanoparticles for Tumor-Targeting Gene Therapy and Their 1 + 1 > 2 Synergistic Effects.

Gene therapy is regarded as one of the most potential technologies for tumor therapy. Gene delivery systems with high specificity and good biocompatibility are urgently demanded. Hence, in this research, we designed and synthesized a series of tumor targeting and redox-responsive gold nanoparticles conjugated with three kinds of functional polypeptides (AuNPPs) that consisted of targeting peptide GE11, cell-penetrating peptide octaarginine (R8), and polyhistidine. All the AuNPPs exhibited superior cancer cellular internalization ability and targeting gene transfection efficiency compared with commercial agent BPEI 25K. It is interesting to find that different relative positions of GE11 and R8 can cause the change of target ability and gene transfection efficiency, and the suitable relative position of R8 and GE11 can not only endow the gene vector with functions that peptides previously own but also bring the synergistic effects. The best-performed AuNPP6-1 was chosen to transport the epidermal growth factor receptor (EGFR)-shRNA into A549 tumor-bearing BALB/c nude mice, and in vivo fluorescence imaging showed AuNPP6-1 mainly accumulated in tumor sites and achieved a great targeting therapy effect. These results provide significantly important information on understanding and constructing the tumor-targeting gene vector.

DNA-Inspired Adhesive Hydrogels Based on the Biodegradable Polyphosphoesters Tackified by a Nucleobase.

Since adhesive hydrogels showed wide applications ranging from wearable soft materials to medical sealants, more and more attention has been paid toward the exploration of novel adhesive hydrogels. However, the difficulty in removing the residue caused by the excessive adhesive strength and sluggish degradation or nondegradation behaviors of the adhesive has always been challenging. Inspired by the multiple complementary hydrogen bond interactions in DNA, the bioinspired nucleobase (A, T, and U) monomers were first synthesized and used to tackify polyphosphoester hydrogels. The multiple hydrogen bonds and hydrophobic interactions between purine rings and pyrimidine functionalities endowed the hydrogels with excellent controllable adhesive properties. Besides this, it has been found that these nucleobase-tackified hydrogels could be easily peeled off without leaving any residue and could be totally degraded under alkaline conditions due to hydrolysis of phosphoester chains. At the same time, they also exhibited controllable biodegradation to different extents under the different pH conditions. The excellent adhesive performance, controllable biodegradation, and excellent biocompatibility showed by this nucleobase-tackified polyphosphoester adhesive hydrogel demonstrated its great potential in wound dressing, as a tissue sealant, and so on.

Predicting Protein-Protein Interactions from Matrix-Based Protein Sequence Using Convolution Neural Network and Feature-Selective Rotation Forest.

Protein is an essential component of the living organism. The prediction of protein-protein interactions (PPIs) has important implications for understanding the behavioral processes of life, preventing diseases, and developing new drugs. Although the development of high-throughput technology makes it possible to identify PPIs in large-scale biological experiments, it restricts the extensive use of experimental methods due to the constraints of time, cost, false positive rate and other conditions. Therefore, there is an urgent need for computational methods as a supplement to experimental methods to predict PPIs rapidly and accurately. In this paper, we propose a novel approach, namely CNN-FSRF, for predicting PPIs based on protein sequence by combining deep learning Convolution Neural Network (CNN) with Feature-Selective Rotation Forest (FSRF). The proposed method firstly converts the protein sequence into the Position-Specific Scoring Matrix (PSSM) containing biological evolution information, then uses CNN to objectively and efficiently extracts the deeply hidden features of the protein, and finally removes the redundant noise information by FSRF and gives the accurate prediction results. When performed on the PPIs datasets Yeast and Helicobacter pylori, CNN-FSRF achieved a prediction accuracy of 97.75% and 88.96%. To further evaluate the prediction performance, we compared CNN-FSRF with SVM and other existing methods. In addition, we also verified the performance of CNN-FSRF on independent datasets. Excellent experimental results indicate that CNN-FSRF can be used as a useful complement to biological experiments to identify protein interactions.

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 ß-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 PEI25k . The results demonstrated that the hydrogen-bond-induced ultrasensitive esters could be powerfully applied to construct gene delivery systems.

ROS-Response-Induced Zwitterionic Dendrimer for Gene Delivery.

As one of the most promising therapeutic methods, gene therapy has been playing a more and more important role in treating disease due to its ultra-high therapy efficiency. Even if nonviral gene vectors represented by polycation, liposomal, dendrimers, and zwitterionic materials have made great progress in gene complexation, low immunogenicity, and biocompatibility, intracellular gene release with low toxicity is effectively still a bottleneck restricting the clinical application of gene therapy. We designed and synthesized a reactive oxygen species (ROS)-responsive dendrimer poly(amido amine)- N-(4-boronobenzyl)- N, N-diethyl-2-(propionyloxy)ethan-1-aminium (PAMAM-(B-DEAEP)16) as a gene vector whose potential can vary from positive to negative under the elevated ROS (H2O2) in cancerous cells. Dynamic light scattering results showed that the zeta potential of PAMAM-(B-DEAEP)16 decreased from +12.3 to -5 mV under 80 mM H2O2 in PBS buffer. The 1H NMR results demonstrated that the intermediate status of PAMAM-(B-DEAEP)16 was zwitterionic in ∼6 h because it consisted of the positive quaternary ammonium and negative carboxylic acid simultaneously before the ester bond was completely hydrolyzed. Gel retardation assay showed that PAMAM-(B-DEAEP)16 can condense DNA at above N/P = 1; then, PAMAM-(B-DEAEP)16 transfers to zwitterionic, which begins to continuously release DNA with the decrease in the positive charges and increase in the negative charges, and finally to negatively charged poly(amido amine)-propionic acid (PAMAM-PAc16) in the 80 mM H2O2. Fluorescence-labeled Cy-5 DNA indicated that PAMAM-(B-DEAEP)16 can enter into the cell completely in ∼4 h. The results showed that this compound we designed exhibited higher gene transfection efficiency and lower cytotoxicity than commercial PEI. This is the first time that the positively charged dendrimer was transferred to zwitterionic dendrimer under the stimuli of H2O2 and was successfully applied to gene delivery. Unlike all of the previous reports, we did not seek a compromise between the high gene transfection and low toxicity but find a new avenue to make the gene carrier not only have higher gene transfection efficiency but also exhibit lower toxicity by introducing stimuli-sensitive groups into the positively charged dendrimer to make it capable of adjusting the charge property according to the microenvironment. This study not only provides a good method to design materials for gene delivery but also opens a new perspective to understand the process of gene delivery.

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.

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

Limited cellular uptake and inefficient intracellular drug release severely hamper the landscape of polymer drug nanocarriers in cancer chemotherapy. Herein, to address these urgent challenges in tumor treatment simultaneously, we integrated the multivalent choline phosphate (CP) and bioreducible linker into a single polymer chain, designed and synthesized a neoteric bioreducible polymer nanocarrier. The excellent hydrophility of these zwitterionic CP groups endowed high drug loading content and drug loading efficiency of doxorubicin to this drug delivery system (∼22.1 wt %, ∼95.9%). Meanwhile, we found that the multivalent choline phosphate can effectively enhance the internalization efficiency of this drug-loaded nanocarrier over few seconds, and the degree of improvement depended on the CP density in a single polymer chain. In addition, after these nanocarriers entered into the tumor cells, the accelerated cleavage of bioreducible linker made it possible for more cargo escape from the delivery system to cytoplasm to exert their cytostatic effects more efficiently. The enhanced therapeutic efficacy in various cell lines indicated the great potential of this system in anticancer drug delivery applications.

Investigation of the Effect of Thermal Annealing on Poly(3-hexylthiophene) Nanofibers by Scanning Probe Microscopy: From Single-Chain Conformation and Assembly Behavior to the Interfacial Interactions with Graphene Oxide.

Poly(3-hexylthiophene) (P3HT) has been widely used in devices owing to its excellent properties and structural features. However, devices based on pure P3HT have not exhibited high performance. Strategies, such as thermal annealing and surface doping, have been used to improve the electrical properties of P3HT. In this work, different from previous studies, the effect of thermal annealing on P3HT nanofibers are examined, ranging from the single polymer chain conformation to chain packing, and the interfacial interactions with graphene oxide (GO) at nanoscale dimensions, by using scanning tunneling microscopy (STM), atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). High-resolution STM images directly show the conformational changes of single polymer chains after thermal annealing. The morphology of P3HT nanofibers and the surface potential changes of the P3HT nanofibers and GO is further investigated by AFM and KPFM at the nanoscale, which demonstrate that the surface potentials of P3HT decrease, whereas that of GO increases after thermal annealing. All of the results demonstrate the stronger interfacial interactions between P3HT and GO occur after thermal treatments due to the changes in P3HT chain conformation and packing order.

Reverse engineering of gene regulatory network using restricted gene expression programming.

Inference of gene regulatory networks has been becoming a major area of interest in the field of systems biology over the past decade. In this paper, we present a novel representation of S-system model, named restricted gene expression programming (RGEP), to infer gene regulatory network. A new hybrid evolutionary algorithm based on structure-based evolutionary algorithm and cuckoo search (CS) is proposed to optimize the architecture and corresponding parameters of model, respectively. Two synthetic benchmark datasets and one real biological dataset from SOS DNA repair network in E. coli are used to test the validity of our method. Experimental results demonstrate that our proposed method performs better than previously proposed popular methods.

Tailor-Made pH-Responsive Poly(choline phosphate) Prodrug as a Drug Delivery System for Rapid Cellular Internalization.

Rapid cellular uptake and efficient drug release in tumor cells are two of the major challenges for cancer therapy. Herein, we designed and synthesized a novel pH-responsive polymer-drug conjugate system poly(2-(methacryloyloxy)ethyl choline phosphate)-b-poly(2-methoxy-2-oxoethyl methacrylate-hydrazide-doxorubicin) (PCP-Dox) to overcome these two challenges simultaneously. It has been proved that PCP-Dox can be easily and rapidly internalized by various cancer cells due to the strong interaction between multivalent choline phosphate (CP) groups and cell membranes. Furthermore, Dox, linked to the polymer carrier via acid-labile hydrazone bond, can be released from carriers due to the increased acidity in lysosome/endosome (pH 5.0-5.5) after the polymer prodrug was internalized into the cancer cells. The cell viability assay demonstrated that this novel polymer prodrug has shown enhanced cytotoxicity in various cancer cells, indicating its great potential as a new drug delivery system for cancer therapy.

Monochloro non-bridged half-metallocene-type zirconium complexes containing phosphine oxide-(thio)phenolate chelating ligands as efficient ethylene polymerization catalysts.

A series of novel monochloro half-zirconocene complexes containing phosphine oxide-(thio)phenolate chelating ligands of the type, ClCp'Zr[X-2-R(1)-4-R(2)-6-(Ph(2)P=O)C(6)H(2)](2) (Cp' = C(5)H(5), 2a: X = O, R(1) = Ph, R(2) = H; 2b: X = O, R(1) = F, R(2) = H; 2c: X = O, R(1) = (t)Bu, R(2) = H; 2d: X = O, R(1) = R(2) = (t)Bu; 2e: X = O, R(1) = SiMe(3), R(2) = H; 2f: X = S, R(1) = SiMe(3), R(2) = H; Cp' = C(5)Me(5), 2g: X = O, R(1) = SiMe(3), R(2) = H), have been synthesized in high yields. These complexes were identified by (1)H {(13)C} NMR and elemental analyses. Structures for 2b, 2c and 2f were further confirmed by X-ray crystallography. Structural characterization of these complexes reveals crowded environments around the zirconium. Complexes 2b and 2c adopt six-coordinate, distorted octahedral geometry around the zirconium center, in which the equatorial positions are occupied by three oxygen atoms of two chelating phosphine oxide-bridged phenolate ligands and a chlorine atom. The cyclopentadienyl ring and one oxygen atom of the ligand are coordinated on the axial position. Complex 2f also folds a six-coordinate, distorted octahedral geometry around the Zr center, consisting of a Cp-Zr-O (in P=O) axis [177.16°] and a distorted plane of two sulfur atoms and one oxygen atom of two chelating phosphine oxide-bridged thiophenolate ligands as well as a chlorine atom. When activated by modified methylaluminoxane (MMAO), all the complexes exhibited high activities towards ethylene polymerization at high temperature (75 °C), giving high molecular weight polymers with unimodal molecular weight distribution. The formation of 14-electron, cationic metal alkyl species might come from the Zr-O (in phenol ring) bond cleavage based on the DFT calculations study.