骨髓基质干细胞在IKVAV多肽纳米纤维凝胶表面增殖、黏附及向神经细胞诱导分化的研究

目的研究骨髓基质干细胞（BMSCs）与IKVAV多肽纳米纤维凝胶复合的细胞假体应用于脊髓损伤治疗的可行性。方法合成IKVAV多肽两亲性分子，进行自组装，用透射电镜检测。将IKVAV多肽纳米纤维凝胶与BMSCs复合培养，采用倒置显微镜下观察、Calcein—AM／PI染色、CCK-8法、免疫荧光双标法，检测IKVAV多肽对BMSCs增殖、黏附及向神经细胞方向诱导分化的影响。结果IKVAV多肽可成功自组装成纳米纤维凝胶，其与BMSCs复合培养细胞生长良好，活细胞数达90％以上，IKVAV多肽对BMSCs增殖没有影响，可促进BMSCs的黏附，并在诱导BMSCs向神经细胞分化过程中提高神经元分化比例。结论BMSCs在IKVAV多肽纳米纤维凝胶材料表面可良好的增殖及黏附，并可提高其向神经细胞分化过程中神经元的分化比例。     

Controlled Release of the Indomethacin Microencapsulation Based on Layer-by-layer Assembly by Polyelectrolyte Multilayers

Indomethacin has been encapsulated with polyelectrolyte multilayers for controlled release. Gelatin and alginate were alternatively deposited on indomethacin microcrystals. The released amount of indomethacin from coated microcrystals in pH6. 8 phosphate buffer solution （PBS） was measured with a UV spectrophometer. The polyelectrolyte multilayer capsule thickness was proved to control the release rate. The effects of osmotic pressure existed during the release process of indomethacin from microcapsules coated by （gelatin/alginate） 4.     

Impact of the amount of PEG on prodrug nanoassemblies for efficient cancer therapy

PEGylation has been widely used to improve the pharmacokinetic properties of prodrug self-assembled nanoparticles (prodrug-SANPs). However, the impacts of the amount of PEG on the self-assemble stability, cellular uptake, pharmacokinetics, and antitumor efficacy of prodrug-SANPs are still unknown. Herein, selenoether bond bridged docetaxel dimeric prodrug was synthesized as the model prodrug. Five prodrug-SANPs were designed by using different mass ratios of prodrugs to PEG (W_prodrug/W_{DSPE-mPEG2000} = 10:0, 9:1, 8:2, 7:3 and 6:4), and defined as Pure drug NPs, 9:1NPs, 8:2NPs, 7:3 NPs and 6:4 NPs, respectively. Interestingly, 8:2 NPs formed the most compact nanostructure, thus improving the self-assemble stability and pharmacokinetics behavior. In addition, the difference of these prodrug-SANPs in cellular uptake was investigated, and the influence of PEG on cytotoxicity and antitumor efficacy was also clarified in details. The 8:2 NPs exhibited much better antitumor efficacy than other prodrug-SANPs and even commercial product. Our findings demonstrated the pivotal role of the amount of PEG on prodrug-SANPs.     

The promotion of functional urinary bladder regeneration using anti-inflammatory nanofibers

Current attempts at tissue regeneration utilizing synthetic and decellularized biologic-based materials have typically been met in part by innate immune responses in the form of a robust inflammatory reaction at the site of implantation or grafting. This can ultimately lead to tissue fibrosis with direct negative impact on tissue growth, development, and function. In order to temper the innate inflammatory response, anti-inflammatory signals were incorporated through display on self-assembling peptide nanofibers to promote tissue healing and subsequent graft compliance throughout the regenerative process. Utilizing an established urinary bladder augmentation model, the highly pro-inflammatory biologic scaffold (decellularized small intestinal submucosa) was treated with anti-inflammatory peptide amphiphiles (AIF-PAs) or control peptide amphiphiles and used for augmentation. Significant regenerative advantages of the AIF-PAs were observed including potent angiogenic responses, limited tissue collagen accumulation, and the modulation of macrophage and neutrophil responses in regenerated bladder tissue. Upon further characterization, a reduction in the levels of M2 macrophages was observed, but not in M1 macrophages in control groups, while treatment groups exhibited decreased levels of M1 macrophages and stabilized levels of M2 macrophages. Pro-inflammatory cytokine production was decreased while anti-inflammatory cytokines were up-regulated in treatment groups. This resulted in far fewer incidences of tissue granuloma and bladder stone formation. Finally, functional urinary bladder testing revealed greater bladder compliance and similar capacities in groups treated with AIF-PAs. Data demonstrate that AIF-PAs can alleviate galvanic innate immune responses and provide a highly conducive regenerative milieu that may be applicable in a variety of clinical settings.     

Maximizing gene delivery efficiencies of cationic helical polypeptides via balanced membrane penetration and cellular targeting

The application of non-viral gene delivery vectors is often accompanied with the poor correlation between transfection efficiency and the safety profiles of vectors. Vectors with high transfection efficiencies often suffer from high toxicities, making it unlikely to improve their efficiencies by increasing the DNA dosage. In the current study, we developed a ternary complex system which consisted of a highly membrane-active cationic helical polypeptide (PVBLG-8), a low-toxic, membrane-inactive cationic helical polypeptide (PVBLG-7) capable of mediating mannose receptor targeting, and DNA. The PVBLG-7 moiety notably enhanced the cellular uptake and transfection efficiency of PVBLG-8 in a variety of mannose receptor-expressing cell types (HeLa, COS-7, and Raw 264.7), while it did not compromise the membrane permeability of PVBLG-8 or bring additional cytotoxicities. Because of the simplicity and adjustability of the self-assembly approach, optimal formulations of the ternary complexes with a proper balance between membrane activity and targeting capability were easily identified in each specific cell type. The optimal ternary complexes displayed desired cell tolerability and markedly outperformed the PVBLG-8/DNA binary complexes as well as commercial reagent Lipofectamine™ 2000 in terms of transfection efficiency. This study therefore provides an effective and facile strategy to overcome the efficiency-toxicity poor correlation of non-viral vectors, which contributes insights into the design strategy of effective and safe non-viral gene delivery vectors.     

Matrix metalloproteinase 2-sensitive multifunctional polymeric micelles for tumor-specific co-delivery of siRNA and hydrophobic drugs

Co-delivery of hydrophilic siRNA and hydrophobic drugs is one of the major challenges for nanomaterial-based medicine. Here, we present a simple but multifunctional micellar platform constructed by a matrix metalloproteinase 2 (MMP2)-sensitive copolymer (PEG-pp-PEI-PE) via self-assembly for tumor-targeted siRNA and drug co-delivery. The micellar nanocarrier possesses several key features for siRNA and drug delivery, including (i) excellent stability; (ii) efficient siRNA condensation by PEI; (iii) hydrophobic drug solubilization in the lipid “core”; (iv) passive tumor targeting via the enhanced permeability and retention (EPR) effect; (v) tumor targeting triggered by the up-regulated tumoral MMP2; and (vi) enhanced cell internalization after MMP2-activated exposure of the previously hidden PEI. These cooperative functions ensure the improved tumor targetability, enhanced tumor cell internalization, and synergistic antitumor activity of co-loaded siRNA and drug.     

Self-assembly LiFePO4/polyaniline composite cathode materials with inorganic acids as dopants for lithium-ion batteries

Carbon-coated LiFePO₄ (C-LFP) composites incorporated with electrochemically-active conducting polymer polyaniline (PANI) are fabricated via a self-assembly process. Inorganic acids HCl, H₂SO₄ and H₃PO₄ are used as dopants for PANI. The C-LFP/PANI composites are characterized by thermogravimetric analysis, scanning electron microscopy, electrochemical impedance spectroscopy, Raman spectra and four-probe resistivity measurements. Our results show that a remarkable improvement in capacity and rate capability can be achieved in the C-LFP/PANI composite cathodes doped with HCl and H₃PO₄. The C-LFP/PANI-HCl composite exhibits the best electrochemical performance, which gives a ca. 15% capacity enhancement at 0.2 C and 40% enhancement at 5 C compared to the parent C-LFP. The mechanism for the enhancement has been discussed.     

Self-assembled drug delivery systems. Part 4. In vitro/in vivo studies of the self-assemblies of cholesteryl-phosphonyl zidovudine

An amphiphilic prodrug of anti-HIV nucleoside analogue, cholesteryl-phosphonyl zidovudine (CPNZ) was synthesized. An aqueous suspension containing CPNZ self-assemblies was obtained through injecting the ethanol solution of CPNZ and cholesteryl succinyl poly(ethylene glycol) 1500 (20:1, mol/mol) into water under agitation. Hydrophobic interaction may be the driving force of molecular self-assembly. The self-assemblies were nanoscale with ∼100 nm in size, and remained stable for a long time. Degradation of CPNZ self-assemblies was investigated in various environments including buffered solutions, plasma and rabbit tissue homogenates. CPNZ was degraded very slowly in neutral solutions but rapidly in various plasma with the half-lives (t_1/2) of less than 20 h. Tissue homogenates degraded CPNZ with varied rates depending on enzyme activity. CPNZ self-assemblies showed potent anti-HIV activity on MT4 cell model, the anti-HIV 50% effective concentration (EC₅₀) of which was 1 nM, only equal to 1/5 of AZT EC₅₀. CPNZ was rapidly eliminated from circulation and distributed into the mononuclear phagocyte system (MPS) including liver, spleen and lung after bolus intravenous administration of CPNZ self-assemblies followed slowly elimination. The possible products include AZT-5′-H-phosphonate, AZT and their derivatives. The MPS-targeted effect and high anti-HIV activity of CPNZ self-assemblies make them become a promising self-assembled drug delivery system (SADDS).     

Novel immunoadjuvants based on cationic lipid: Preparation,characterization and activity in vivo

The interactions between three different protein antigens and dioctadecyldimethylammonium bromide (DODAB) dispersed in aqueous solutions from probe sonication or adsorbed as one bilayer onto particles was comparatively investigated. The three model proteins were bovine serum albumin (BSA), purified 18 kDa/14 kDa antigens from Taenia crassiceps (18/14-Tcra) and a recombinant, heat-shock protein hsp-18 kDa from Mycobacterium leprae. Protein-DODAB complexes in water solution were characterized by dynamic light scattering for sizing and zeta-potential analysis. Cationic complexes (80–100 nm of mean hydrodynamic diameter) displayed sizes similar to those of DODAB bilayer fragments (BF) in aqueous solution and good colloid stability over a range of DODAB and protein concentrations. The amount of cationic lipid required for attaining zero of zeta-potential at a given protein amount depended on protein nature being smaller for 18 kDa/14 kDa antigens than for BSA. Mean diameters for DODAB/protein complexes increased, whereas zeta-potentials decreased with NaCl or protein concentration. In mice, weak IgG production but significant cellular immune responses were induced by the complexes in comparison to antigens alone or carried by aluminum hydroxide as shown from IgG in serum determined by ELISA, delayed type hypersensitivity reaction from footpad swelling tests and cytokines analysis. The novel cationic adjuvant/protein complexes revealed good colloid stability and potential for vaccine design at a reduced DODAB concentration.     

两亲性含IKVAV的肽体内诱导血管生成的研究

目的设计合成含IKVAV的两亲性肽，探讨其体外自组装成三维多孔凝胶及体内诱导血管生成的可行性。方法固相法合成肽．自组装成凝胶，TEM观察凝胶结构。实验组：配制1wt％的肽溶液，pH值为9．0；对照组：配制16．67％的明胶，DH值为7．4。各取1mL，分别注射于大鼠脊柱两侧皮下，术后1周观察全身反应及局部皮肤。2周后取材，固定，常规HE染色及VEGF免疫组织化学染色。结果高效液相频谱仪及质谱仪示肽纯度及分子量分别为95．22％与1438,TEM示凝胶为交织成网状的纳米纤维。术后1周动物存活良好，无全身不良反应，局部皮肤无红肿、无坏死。实验组：1wt％的肽体内自组装成凝胶，血管长入凝胶内部，管腔内可发现红细胞；术后2周，VEGF阳性。对照组：明胶内未发现血管，VEGF阴性。结论本实验合成含IKVAV两亲性肽，在PBS溶液中可自组装成凝胶且体内可诱导新生血管生成。